INTRODUCTION

The Aghanashini, also known as Tadri River has a total length of 181 km. It originates as Bakurhole at Manjuguni near Sirsi in the Western Ghats of Uttara Kannada district. Another source, closer to Sirsi is Donihalla. The streams meet near Mutthalli about 16 km south of Sirsi. The river, winding its westerly way through the Western Ghats leaps down the Ghats at Unchalli as Lushington Falls. Further down, six km from Bilgi it has another smaller fall namely Burde Jog. The river meets the tide at Uppinpatana in Kumta taluk, 24 km upstream in the River. The river in the coastal zone has two towns, Kumta to its south and the ancient temple town town of Gokarna to the north. At Mirjan it widens into an estuarine expanse for the next 13 km length to Aghanashini village in the south towards south of the river mouth and Tadri, a small fishing port to in the north. This backwater expanse is 2-6 km wide and joins the Arabian Sea between two hills one 91 m in height and the other about 122 km high (Kamath, 1985). Aghanashini and Gangavali are two ancient rivers of the planet, springing from the Western Ghats, descending rapidly towards the west coast and meeting the Arabian Sea towards their confluence forming two important estuaries, rich in diversity and endowed with tremendous capacity to support human livelihoods. The Western Ghats of India (along with the west coast obviously, as the Ghats intrude into the Arabian Sea in many places), one of the 34 Global Biodiversity Hotspots along with Sri Lanka, , constitute an important ecological region. Springing from the Sea coast to the montane heights exceeding 2500 m, especially in southern parts, and having rainfall ranging from barely 1,000 mm, along its rain-shadow eastern parts to well over 6,000 mm in the western portions, the landscapes of Western Ghats-west coast are very heterogeneous. Clad in a range of forests from the tropical evergreen to dry deciduous, and its colder heights of rolling grasslands and stunted evergreen shola woods often enveloped by mists and clouds the mountain remained untrammeled by humans, in its pristine glory, until the early beginnings of agriculture in the region, around 3500 years ago. Everything about the region would have been primary until then as the vegetation and landscapes remained unaltered, although the human influence began some 15-20 thousand years ago with the colonization of hunter gatherers along the hilly terrain and fishing people along the coast. Such late colonization is in contrast to human arrival in the South Indian plains over 1.2 million years ago (Chandran, 1997; Chandran and Ramachandra, 2011).

Figure 1: Aghanashini River and estuary

The estuary: At Uppinpatan village in Kumta (Figure 1), Aghanashini River meets the tide from the Arabian Sea. From thereon for 21 km length is the estuarine area. At Mirjan it flattens into a wider estuary, which has few small islands mainly Aigalkurve (inhabited) and Masurkurve (uninhabited). The estuary proper lies between lat. 14.391° to 14.585° N and long. 74.304° to 74.516° E in the Kumta taluk. The main water-spread area (including the floodplain) of the estuary is aligned parallel to the sea coast, leaving a narrow strip of land 1-1.5 km wide constituted of sand and alluvium, between Arabian Sea and the estuary. This strip of land with several villages is a densely populated tract. Substantial portion of the population are traditionally engaged in fishing, bivalve collection, fish and shrimp culturing, salinity tolerant rice cultivation in in gajni rice fields, salt making etc. In the recent decades mining sand and bivalve shells have emerged as major activities too. The main body of estuary is 13 km long and 2-6 km wide (Figure 2).

Figure 2: salinity zones and gajani fields cum aquaculture areas in Aghanashini estuary

The total water spread area is 4940 ha which excludes estuarine rice fields and aquaculture farms. About 2800 ha is under high salinity in the pre-monsoon times, 1900 ha under medium salinity, and the rest, towards the narrower part upstream, merging with the fresh water portion within the bounds of Uppinpatan village, experiences low salinity (<10 ppt). This last mentioned portion, mostly bounded by low hills and plateaus covered with indurated laterite, sloping towards the river, contributes hardly any silt laden water to the river, as the runoff water during rains, from this inner coastal zone is clear, unless the hills are dug exposing the clayey soil beneath. This low (5-10 ppt) and medium (10-20 ppt) salinity portions, where the flow of water, both of rains and of tides, is faster due to the narrowness of the river, is the main portion allotted for sand mining. The wider part of the estuary, its main body, has no sand extraction blocks allotted . Between the villages Gokarna in the north and Aghanashini in the south the estuary turns to the west towards the Arabian Sea. The river mouth, situated between two laterite hills bordering the sea, is very stable. The Tadri fishery port is situated towards the north bank of the river mouth bordering Gokarna village. Before the road networks came the estuary was a major route for transportation of pilgrims to Gokarna. The picturesque estuary with flourishing mangrove vegetation (Figure 2), its rich birdlife, and traditional way of life of the people need to be protected as a cultural heritage and draw for tourism.

Gazni farming system: survival of an ancient cooperative: Vast stretches of shallow, intertidal portions, alongside Aghanashini estuary have been embanked and converted to rice fields or gaznis where the salt tolerant, indigenous, Kagga rice has been grown from ancient times. In the recent decades many of these gaznis have been diverted towards shrimp farming after flooding them with tidal waters. The gaznirice fields of Aghanashini are instances of traditional co-operative farming, of several families together owning a single field, of few to few hundred hectares, and cultivating it collectively and sharing the product. When many of these gaznis were utilized for fish/prawn farming the collective system of sharing the benefits continued (Figure 2).

EVALUATION CRITERIA

Group A: Sites containing representative, rare or unique wetlands types
Criteria 1	A wetland contains representative, rare, or unique example of natural or near-natural wetland type
Group B: Sites of International importance for conserving biological diversity
Criteria 2	A wetland should supports vulnerable, endangered, or critically endangered species or threatened ecological communities.
Criteria 3	A wetland should support populations of plant and /or animal species important for maintaining the biological diversity of a particular biogeographic region
Criteria 4	A wetland should support plant and/or animal species at a critical stage in their life cycles, or provide refuge during adverse conditions
Specific criteria based on water birds
Criteria 5	A wetland should support 20000 or more water birds
Criteria 6	A wetland should support 1% of the individuals in a population of one species or subspecies of water bird
Specific criteria based on fish
Criteria 7	A wetland should support a significant proportion of indigenous fish subspecies, species of families, life-history stages, species interactions and/ or populations that are representative of wetland benefits and/or values and thereby contributes to global biological diversity
Criteria 8	A wetland should be an important source of food for fishes, spawning ground, nursery and/or migration path on which fish stocks, either within the wetland or elsewhere, depend
Specific criteria based on other taxa
Criteria 9	A wetland should support 1% of the individuals in population of one species or subspecies of wetland-dependent non-avian animal species.

Group A: Sites containing representative, rare or unique wetlands types
Criteria 1	Aghanashini estuary contains representative, rare, or unique example of natural or near-natural wetland type supports diverse biota including human livelihood, evident from 6500-7000 families dependence on the ecosystem for natural resources apart from aiding as filters, shoreline protection, diverse habitats (mudflats, sand flats, etc.) and diverse micro and macro biota

Aghanshini estuary: Aghanashini River originates in Western Ghats flowing westwards into Arabian Sea. The river joins the sea in Aghanashini village of Kumta taluk forming a productive ecosystem- estuary, about 48sq km (lat. 14.3910-14.5850oN, long 74.3040-74.5160 oE). Aghanashini estuary provides livelihood for large number of individuals residing along the estuary. The provisioning services provided by this estuary  is about 11,35,847 Rs/hectare/year, which highlights the significance of an estuarine ecosystem in sustaining livelihood of 6000 - 7500 families. The total economic value (provisioning, regulating, supporting and information services) of Aghanashini is 50,05,035 Rs/hectare/year. This highlights the contributions by estuarine ecosystems in sustaining the economy of the district while providing jobs to thousands of ecosystem people in the region. Quantification of all benefits associated with the ecosystem goods and services, would help in arriving at an appropriate policy and managerial decisions. This also emphasizes the need for green GDP (Gross domestic product) through incorporation of ecosystem goods and services in the national and regional accounting to ensure the sustainability of natural resources (water, energy, land, etc.). In the absence of such accounting, decisions are skewed in favor of environmentally degrading practices by neglecting the diffuse social interests that benefit from the use and non-use values and benefits of fragile ecosystems. Most of the communities residing in and around estuary are dependent on the resources such as; crabs, fishes, bivalves, and mangroves available in the estuary (Table 1). 40% migratory birds visit this estuary during winter seasons contributing to the rich nutrient cycling in the estuary by castings.

Table 1. Aghanshini estuary resources
Resources	Total number of species	References
Mangroves	13	Chandran et al., (2012a)
Bivalves	6	Ramachandra et al., (2012)
Crabs	33	Ganesh et al., (2017)
Fishes	77	Bhat et al., (2014)
Birds	108	Chandran et al., (2012b)

Aghanashini estuarine landforms not only accommodate diverse ecosystem functions and human activities but also mediate flood and erosion risks that are expected to increase with climate change. The daily mixing of fresh water and saltwater in estuaries is the most important phenomenon leading to variable and dynamic chemical conditions, especially salinity. High tides create saltwater currents and move seawater up into the estuary. Low tides reverse these currents. 

Sedimentation is a very characteristic process associated with estuaries. Waves and tides bring marine sediments from the seabed offshore and build sandy barriers and spits at estuary entrances, from where sand is brought into the estuary by the high tides. From the land side, rivers carry finer sediments into the estuary. Upstream deforestation and construction activities lead to soil erosion and sedimentation in estuaries.

Estuaries are unique places, strongly affected by tidal action, where land, river and sea merge into a dynamic natural complex. Fishes, birds and animals congregate to feed, find refuge, grow to adulthood and stage migrations. This estuary is ranked among other estuaries in the West coast as the biologically richest ecosystems with the mean annual primary production rate at > 1500 g/m2 of dry matter. This estuary is a mosaic of various habitats typical of tropical estuaries - mangrove forests, saltmarshes, shallow open waters, mudflats, shell beds, sea grass meadows, sandy, muddy and rocky shores etc.  

The filtering capacity or retention factor of an estuary is a measure of the contaminants removed during their transport through the estuary to the sea. Estuaries are sinks for suspended particles carried down into them by rivers, sedimentation in them can account for a substantial reduction of the contaminant load transported to the sea. Biodegradation and volatization are also estuarine processes involved in removing especially organic micropollutants. As water flows through a saltmarsh, marsh grasses filter pollutants out of the water, as well as excess sediments and nutrients (USEPA 1993).

 ‘Living shorelines’ based on natural and nature-based features are viable approach to conserving coastal habitats (marshes, beaches, shallows, sea grasses) along eroding shorelines. Living shorelines typically involve the use of coastal habitats, such as wetlands, that have a natural capacity to stabilize the shore, restore or conserve habitats and maintain coastal processes. 

The mangrove community, apart from having woody mangrove trees and mangrove-associate shrubs, trees and climbers, also harbours a great complex of organisms, organized into complex ecosystems that function within the bounds of estuaries and in the marine regions. These organisms include microbes (bacteria, protozoa, fungi, cyanobacteria), meio-organisms (nematodes, copepods, polychaetes, oligocheates, etc.) and macro-organisms (polychaetes, molluscs, crustaceans, holothurians, etc.).

Tidal flats are found in intertidal areas, at the conjunction of fresh water, marine and land environments. Tidal flats are areas where sediments from river runoff, or inflow from tides, deposit mud or sand. If the energy of the waves beating on these shores is low, then small-grained sediment or mud is deposited in this area and form mudflats.  Mudflats are some of the most productive marine habitats. They are nutrient traps because of their shallowness and slow-moving water. Mudflats are intertidal areas made up of fine silts and clays or mud. The gentle movement of saltwater inland brings fine sediments, and the slow movement of the river also brings fine sediments. The organisms living in these habitats can withstand the changing environmental conditions, especially salinity and hypoxic and anoxic conditions; but there is plenty of food and a relative lack of competition. Tidal flats, especially mudflats, are highly productive and therefore of high conservation importance. Among the fishes of mudflats, in general, are the predatory eels, which often remain partly burrowed in sandy/muddy bottoms, ambushing small fishes, decapods, invertebrates and also feeding on detritus.

The coastal zone, being a complex of closely interacting ecosystems involving, land, river, estuary and the sea, has been favoured for human settlements from time immemorial, compared with interior landscapes. As anthropogenic pressures mounted on the coastal zone with a flush of developmental interventions, with deleterious consequences, coastal zones the world over are getting threatened most. 

The estuarine system is ever fluctuating, the most decisive physical factors being freshwater input, salinity regimes and the tides and currents, creating significant seasonal changes in the faunal communities.  The dynamic changes in salinity are found as the most influential. This is unlike the marine regime, where the ocean maintains its stability especially in salinity. There are informal and formal governance structures at the grassroot level such as the self-help groups, the Village Forest Committees, the mangrove committees, the several groups of gazni (estuarine rice fields) farmers, fishing communities, bivalve collectors, the Biodiversity Management Committees, the Gram Panchayats etc. and these groups actively participate in the management of estuary.

Aghanashini estuary  is the tidal portion, towards the river mouth is a flat expanse of water dotted with small islands and narrow creeks. This portion is a highly productive and biologically rich waterscape of coastal Karnataka. Whereas hundreds of families in the shore villages have direct dependence on it for their livelihoods through activities related to fishing, agriculture, collection of edible bivalves and crabs, shrimp aquaculture, traditional fish farming in the gazni rice fields, bivalve shell mining, salt production, sand removal, water transportation etc. scores of consumers in the estuarine villages and in places far away are benefited by the productivity of the estuary, of which the mangroves constitute the heart. The high productivity of the estuary is due to the following reasons: 

1. Through millennia the estuary and its environs formed the lifeline of the people and constitute a major cultural and historical heritage of the west coast. It was known as a rice bowl in the historical times and rice surplus was transported through water crafts to other regions. The Mirjan fort on the bank of the estuary built by Bijapur Sultans and the ruins of Aghanashini fort on a hill towards the river mouth giving a commanding view of the sea, the estuary and the Western Ghats are testimonials for the historical and cultural importance of the region. Spices grown in the hinterlands of Western Ghats were traded through the estuary during the European period and earlier to it. Gokarna on its shores has been, from time immemorial, a great place of pilgrimage. Before the road networks came the estuary was a major route for transportation of pilgrims. The beaches dotting the coastline of Gokarna are today well known places of tourism. The picturesque estuary with flourishing mangrove vegetation, its rich birdlife, and traditional way of life of the people need to be protected as a cultural heritage and draw for tourism. 
2. The river water carries large quantity of organic materials from the forests in the catchment area of the Western Ghats and deposits the same in the estuary. The debris becomes important base for food chains operating in the estuary and beyond in the offshore waters of the sea
3. The rich mangrove vegetation has significant role in food supply for the diverse faunal community. The mangrove swamp acts as food rich and protective nurseries even for many species of marine fishes and prawns, which lay eggs in the swamp.  
4. The rich bird community (over 120 species, about half of them winter visitors) associated with the estuarine ecosystem   contributes substantially to the nutrient cycling through their potash and nitrogen rich castings
5. The constant churning and circulation of waters due to flow of fresh water from one side and the tidal influx from the Arabian Sea oxygenates the water and circulates nutrients.

Further, designation of Ramsar Site status to Aghanashini estuary would aid towards comprehensive management of the estuary, in relation to coastal environmental integrity and protection of dependent livelihoods. Also, protection would help migratory species during their annual cycle of movement.

Mangroves constitute the core of estuarine ecosystems. One of the most productive features of coastal ecosystems, mangroves produce nutritionally important detritus used by fishes, prawns, crabs, oysters, etc. Many birds, reptiles and mammals depend on mangroves for shelter/food or both. Mangroves provide protective, productive and economic benefits to coastal communities. They contribute towards the protection and building of shorelines and act as barriers against storm surges and cyclonic destruction. Mangroves are sinks of carbon as well as contain various pollutants of anthropogenic origin. A detailed survey of mangroves in the Aghanashini estuary show that almost 120 ha of mangroves with 12 species, including a mangrove grass, Porteresia coarctata. Also recorded were 45 mangrove-associate species (Chandran et al., 2012).

The estuary provides diverse kinds of habitats (in terms of water depth, salinity, soil nature and rockiness) for different bivalve species. Harvests were higher during the postmonsoon period (November–May) compared with the monsoon (June–October). The bivalve-based economy had an estimated turnover of Rs.57.8 million per year (the market prices had escalated over 10-fold due to bivalve depletion caused by unregulated market forces and habitat degradation by agencies beyond the control of bivalve collectors). It had generated direct employment for 2347 people and provided nutritional security to scores more along the Karnataka coast and in neighbouring states.

The edible bivalves Meretrix meretrix, M. casta, Paphia malabarica, Perna viridis and Crassostera spp. Katelsya opima and Tegillaria granosa occur in high to medium salinity conditions and Villorita cyprinoides in medium to low salinity conditions, which emphasizes the ecosystem management implications of these high value economic species (Boominathan et al. 2012, 2014; Ramachandra et al., 2012).

 

Brachyuran crabs and other crustaceans: With 30 species reported by our team, the brachyuran crab diversity of Aghanashini estuary is the highest among the west coast estuary

The Aghanashini crabs belong to 23 genera from 11 families (Shet et al., 2016). Out of these 10 species are commercially important. It may be that the natural conditions are an important factor for this high diversity in Aghanashini, in terms of the survival of a mosaic of crab habitats with the salinity gradients. These crabs are mainly associated with habitats like mangroves, marshy areas, sandy and rocky shores and subtidal areas.

The prawn resources from the region belong to mainly Metapenaeus dobsoni, M. monoceros, M. affinis, Penaeus monodon, P. merguiensis and P. indicus. The parent populations breed in the sea. The larvae, in different stages, move along with water currents into the estuarine areas. Once the larvae reach the backwaters, they settle towards the bottom, and post-larval juvenile prawns emerge. They move in the estuary and seek suitable habitats, especially the gazni rice fields and marshes, and contribute to the local fishery. 

Naturalness of Aghanashini with the diverse habitats and micro-habitats supports species composition evident from the reporting of 77 fish species (Bhat et al. 2014a).

Aghanashini estuary with microhabitats especially mudflats, mangroves, shallow marshes with reeds and grasses, deep open water, gazni rice fields etc. supports diverse bird fauna, evident from the presence of about 130 species and about 40 per cent are winter migrants. January was noted as being the peak time for birds of the estuary, when the largest congregations happen. Aghanashini merits the status of a conservation reserve for birds for their sheer numbers and the ease with which they can be observed. The birds can be grouped into six categories:

1. Large wading birds like herons, egrets, ibises and spoonbills: Two-thirds of them feed exclusively on fishes.
2. Probing shorebirds: This big group includes plovers, curlews, whimbrels, sandpipers, godwits, stints, ruffs, sanderlings, shanks, waterhens, jacanas, lapwings, stilts, moorhens, pratincoles, turnstones, avocets and curlews. In the Aghanashini estuarine area, 32 species were found, of which only 10 are resident birds.
3. Floating and diving birds: Ducks, grebes, cormorants, darters and teals of 11 species. Of these, four are residents and the rest migrants during winter. Whereas cormorants and darters are piscivorous, pintails, ducks and teals are herbivorous.
4. Aerially searching but water-dependent birds: Gulls, terns and kingfishers belong to this category. Of the 17 species noted, 10 are residents and the rest migrants.
5. Birds of prey: Kites, eagles, shikras, ospreys, owls and kestrels are birds of prey. Among the nine species found, five are residents and four are visitors.
6. Arboreal birds: Probably the largest group of diverse kinds, such as doves, cuckoos, robins, warblers, woodpeckers, flycatchers, parakeets, swallows, thrushes, orioles, sparrows, flowerpeckers, bush larks, shrikes, mynas, babblers, bulbuls, pipits, sunbirds, munias, coucals, wagtails, hoopoes, larks and ioras. Of the 49 species, four are migrants, and the rest are local. 

The estuary, being one of the most natural ones, without any major developmental pressures, is rich in livelihood activities. Fishing is a major activity, and about 6000 fishermen, from different communities, such as Ambigas, Harikantras and Daljis, are engaged in fishery. In bivalve collection and crab capture are engaged still more people. The Ambiga fishermen traditionally fished in rivers and estuaries. They are also presently engaged in marine fishing. They are more residents of mid and upstream villages of the estuary. The Harikantras basically are marine fishermen. They usually fish in mid and downstream estuary. The Dalji fishermen are more sea-going and also use high salinity downstream areas. Almost every half hectare of waterspread has one dependent fisherman. The traditional estuarine fishery never caused any depletion, as the fish trade was limited and a larger fishing area was available to the local fishing communities (Ramachandra and Chandran, 2013).

As regards bivalves collection for a livelihood, the survey reveals that about 2347 persons were engaged in bivalve collection. Of these, 638 were women. The bivalve production was in surplus, being estimated at 22,000 tons, a good portion being sent to Goa and other distant markets (Boominathan et al. 2008).

The crab fishery has been an important subsistence fishery for generations. Crabs mainly constituted the poor man’s food until almost a decade ago. The national and international demand for estuarine crabs has been escalating, and increasing numbers of persons from fishing and non-fishing communities are engaged in crab catching for their livelihoods. As regards Aghanashini estuary the intensification of mangrove plantation by the forest department has substantially increased the crab populations and the employment related to the crab fishery.

Cultivation of the salt-tolerant rice Kagga in the estuarine rice fields has been a major occupation in the estuarine villages for generations. Salt making, water transport, sand and shell mining, mat and basket weaving, boat making, etc. are other livelihood options in the estuary. In recent times, tourism is emerging as an additional source of livelihood in some of the villages of Aghanashini.

Estuaries, more specifically mangrove areas, have the highest quantities of organic carbon storage in the soil to an extent of 1000 tonse of organic arbon in every hectare, which emphasies the role played by this estuary in mitigating climatic changes and consequent impact of a sea level rise. The entire estuary, therefore, has over a million tons of soil organic carbon, which highlights the conservation significance of this biodiversity-rich estuary. 

Various threat factors are emerging, of late, causing degradation of the estuary, its diverse ecosystems and associated traditional livelihoods. Overfishing is a major issue that has not only affected estuary-based livelihoods but is also causing upsets in the marine fishery sector as the nursery function of the estuary for marine organisms is getting undermined in the absence of any sustainable management strategies. Abandoning rice cultivation in several gaznis due to introduction of prawn farming has its own adverse effects on the estuarine ecology and fishery as well as on organic carbon sequestration in the gazni systems. The digging out of shells on a large scale, several thousand tons every year, has been an almost unchecked activity, with adverse consequences on the ecosystem, nutrient cycles and the estuarine productivity feared. Pressure from sand mining on the estuary has been mounting over the last several years. Although the government has realized the need for restricting the sand extraction from the river, it is yet unclear to what extent sand extraction can be permitted without notable adverse consequences on the estuarine ecosystems (Ramachandra et al., 2016).

In the traditional system, resources were exploited or used mostly for family consumption, sale within a limited region and not for any notable commercial gains, whether they be agricultural output or fishery-related products. It is therefore not surprising that the concept of sustainability was not consciously practiced but was inherent in the system itself, as resources were used year after year in a routine fashion without facing any depletion. The exhaustible resource use patterns emerged with introduction of new formulas related to fishery exploitation for large-scale commercial gains and conversion of many traditional rice-cum-fishery estuarine fields into prawn aquaculture ponds (Ramachandra and Chandran 2013).

Traditionally, the estuarine fishing communities of Aghanashini, like the Ambigas, fished mostly in the estuary; the Harikantras fished in the estuary and the sea; the Daljis fished more in the sea and less in the estuary. All of them used only traditional fishing gadgets, and a sense of competition hardly existed. The Patgars and Naiks mainly raised salt-tolerant rice in estuarine rice fields, namely gaznis, during the rainy season, and thereafter used the rice fields for fishery purposes. In the estuarine villages, Halkar and Holangadde, community-based forest conservation and management system prevailed. This system perished in Holangadde under governmental intervention, with the community being asked to surrender the village forest; in contrast, the Halkar community, which approached the Karnataka High Court, succeeded in retaining the control of the community over the village forest (Ramachandra and Chandran 2013).

All these communities have sound traditional knowledge in their respective fields. The fishers knew much about the fish species, their locations and timings and the importance of limiting the catches to the bigger sizes. The agriculturists knew about the technique of raising salt-tolerant rice in specially prepared estuarine rice fields, where the effort was mainly on building and maintenance of embankments fitted with sluice gates and also knew the gazni rice field fishery; however they allowed the local fishers to fish in these gaznis. The Agers were experts in making salt from estuarine water, as they are to this day.

The near-shore estuarine and marine ecosystems function as nurseries, highlights interconnectedness of fishery habitats and underscores the need for protection and conservation of these areas. Therefore, improvement of the quality of these habitats is bound to favour their nursery functions. Mangrove ecosystem provides an ideal nursery and breeding ground to most of the marine and brackish water fish and shell fish. Some marine fishes also spawn in the high-salinity portions of the estuaries.

Aghanashini estuary is one of the richest in finfish diversity evident from the report of 77 species (Bhat et al. 2014a) with 13 species are basically marine, which entered during the pre-monsoon period, when the estuarine mouth had a salt concentration nearly equaling that of seawater; 43 species keep freely moving between the estuary and the marine areas. About 18 species are highly euryhaline in nature, their range extending from the marine region to the fresh water. Only two species were nearly confined to estuarine areas. Many fishes have their own preferable salinity regimes, necessitating their constant movement within the estuary according to the dynamic salinity conditions. It is critical therefore that for an estuary to be rich in fish diversity it have dynamic salinity gradients within itself, caused by differential mixing of fresh water and seawater, which necessitates an appropriate fishery management strategy (Bhat et al. 2014b).

Supporting Publications:

1. Bhat, M., Nayak, V.N., Chandran, M.D.S. and Ramachandra, T.V. 2014a. Fish distribution dynamics in the Aghanashini estuary of Uttara Kannada, west coast of India. Current Science 106(12): 1739–1744.

2. Bhat, M., Nayak, V.N., Chandran, M.D.S. and Ramachandra, T.V. 2014b. Impact of hydroelectric projects on the finfish diversity in the Sharavathi estuary of Uttara Kannada district, central west coast of India. International Journal of Environmental Sciences 5(1): 58–66.

3. Boominathan, M., Chandran, M.D.S. and Ramachandra, T.V. 2008. Economic Valuation of Bivalves in the Aghanashini Estuary, West Coast, Karnataka. ENVIS Technical Report, 30, Centre for Ecological Sciences, Indian Institute of Science, Bangalore.

4. Boominathan, M., Ravikumar, G., Chandran, M.D.S. and Ramachandra, T.V. 2012. The impact of dams on the edible bivalves: A comparative study of Kali and Aghanashini estuaries of Uttara Kannada District, Karnataka, India. In National Conference on Mangrove Wetlands and Near Shore Marine Ecosystems from Sustainability Issues to Management & Restoration, 5–6 March 2012, ed. Ramanathan, A.L. et al., School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.

5. Boominathan, M., Ravikumar, G., Chandran, M.D.S. and Ramachandra, T.V. 2014. Impact of hydroelectric projects on bivalve clams in the Sharavathi estuary of Indian west coast. The Open Ecology Journal 7:52-58.

6. Chandran, M.D.S.,Ramachandra, T.V., Joshi, N.V., Mesta, N.M., Settur, B. and Vishnu, D.M. 2012. Conservation and Management of Mangroves in Uttara Kannada, Central West Coast. ENVIS Tech. Report, 50. Centre for Ecological Sciences, Indian Institute of Science, Bangalore.

7. Ramachandra, T.V. and Chandran, M.D.S. 2013. Traditional Knowledge of the Communities of Aghanashini and Gangavali Estuaries in Uttara Kannada District, Karnataka State. Indo-German Biodiversity Programme. Conservation and Sustainable Management of Existing and Potential Coastal and Marine Protected Areas. CSM-CMPA.

8. Ramachandra, T.V., Chandran, M.D.S., Joshi, N.V. and Boominathan, M. 2012. Edible bivalves of Uttara Kannada district, Karnataka, India. ENVIS Technical Report 48. Centre for Ecological Sciences, Indian Institute of Science, Bangalore.

9. Ramachandra, T.V., Chandran, M.D.S., Naik, S. and Mesta, P. 2016. Sand mining and its impact on ecology of Aghanashini estuary, Uttara Kannada district, Karnataka. ENVIS Technical Report 92. Centre for Ecological Sciences, Indian Institute of Science, Bangalore.

10. Shet, G.N., Chandran, M.D.S. and Ramachandra, T.V. 2016. Brachyuran crabs of Aghanashini estuary, south Indian west coast, Karnataka. Paper presented during Lake 2016: Conference on Conservation and Sustainable Management of Ecologically Sensitive Regions in Western Ghats, 28–30 December, Moodbidri, Dakshina Kannada.

11. US Environmental Protection Agency (USEPA). 1993. National Estuary Program: Challenges facing our estuaries—Key management issues. National Estuary Program.

Group B: Sites of International importance for conserving biological diversity
Criteria 2	A wetland should supports vulnerable, endangered, or critically endangered species or threatened ecological communities.
Criteria 3	A wetland should support populations of plant and /or animal species important for maintaining the biological diversity of a particular biogeographic region
Criteria 4	A wetland should support plant and/or animal species at a critical stage in their life cycles, or provide refuge during adverse conditions

Aghanashini Estuarine Ecosystem: Wetland of International importance for conserving biological diversity

Aghanashini River originates in Western Ghats flowing westwards into Arabian Sea. The river joins the sea in Aghanashini village of Kumta taluk forming a productive ecosystem- estuary, about 48sq km (lat. 14.3910-14.5850oN, long 74.3040-74.5160 oE). Aghanashini estuary provides livelihood for large number of individuals residing along the estuary. Total annual production from estuary is estimated at 22,006 tons valuing about Rs. 57.8 million per annum. Most of the communities residing in and around estuary are dependent on the resources such as; crabs, fishes, bivalves, and mangroves available in the estuary (Table i). Many migratory birds visit this estuary during winter seasons contributing to the rich nutrient cycling in the estuary by castings.

Table i : Aghanshini estuary resources
Resources	Total number of species	References
Mangroves	13	Chandran et al., (2012a)
Bivalves	6	Ramachandra et al., (2012)
Crabs	33	Ganesh et al., (2017)
Fishes	77	Bhat et al., (2014)
Birds	108	Chandran et al., (2012b)

 Economic valuation of an ecosystem aids in the wise use and prudent management of natural resources through the quantification and comparison of various benefits of ecosystem services. The present study focusses on the valuation of ecosystem goods and services from an estuary at Aghanashini, Uttara Kannada district, Karnataka. The provisioning services provided by this estuary is about 11,35,847 Rs/hectare/year, which highlights the significance of an estuarine ecosystem in sustaining livelihood of 6000 - 7500 families. The total economic value (provisioning, regulating, supporting and information services) of Aghanashini is 50,05,035 Rs/hectare/year. This highlights the contributions by estuarine ecosystems in sustaining the economy of the district while providing jobs to thousands of ecosystem people in the region. Quantification of all benefits associated with the ecosystem goods and services, would help in arriving at an appropriate policy and managerial decisions. This also emphasizes the need for green GDP (Gross domestic product) through incorporation of ecosystem goods and services in the national and regional accounting to ensure the sustainability of natural resources (water, energy, land, etc.). In the absence of such accounting, decisions are skewed in favor of environmentally degrading practices by neglecting the diffuse social interests that benefit from the use and non-use values and benefits of fragile ecosystems.

Keywords: estuarine ecosystem, provisioning services, Aghanashini, total economic valuation

 

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Aghanashini Estuarine Ecosystem:
Wetland of International importance for conserving biological diversity

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1.0 INTRODUCTION

Ecosystems consist of biotic and abiotic resources with complex interactions among a fabric of plant, animal, and other microscopic life with the non-living environment (Ramachandra, Vinay, Bharath, et al., 2018; Ramachandra, Bharath, Vinay, 2018; Ramachandra, Sincy, Asulabha, et al., 2018). The ecosystem provides various vital benefits such as food; soil production, erosion and control; climate regulation; water purification; bioenergy, etc. These benefits and services are referred to as ‘Ecosystem services’ and are very crucial for the survival of humans and other organisms on the earth (Ramachandra, Bharath, Subashchandran, et al., 2018; Ramachandra, Vinay, Subashchandran, 2018). The structural components of the ecosystem include physical features (such as land cover, water, sediment and soil profile, the gradient of conditions in water body), biotic compositions (like species, number of individuals and their biomass), etc. Interactions between these elements, i.e., the flow of nutrients, energy, etc. between different ecosystems constitute the functional aspects of an ecosystem. The ecosystem can be broadly categorized as aquatic and terrestrial ecosystem, on the basis of their major source and sink of nutrient, i.e., water or land (Ramachandra, Vinay, Bharath, et al., 2018; Ramachandra, Bharath, Vinay, 2018). Aquatic ecosystem with rich nutrient contents is substantially different from terrestrial ecosystem. Both these ecosystems are dependent upon each other, as there is an overlap of the functional boundary between the two, irrespective of the physical boundaries (Ramachandra, Sincy, Asulabha, et al., 2018).

An estuary is a partially enclosed body of water where the rivers meet sea and the salinity is intermediary to that of marine and fresh water. This makes the estuarine ecosystems unique in their ecological and biological functions (Anoop, Suryaprakash, Umesh, et al., 2008). Forming a dynamic zone of convergence between land and sea, the coastal regions of the earth serve as unique geological, ecological and biological domains of vital importance to a vast array of terrestrial and aquatic life (Wilson, Farber, 2005). These are major specialized ecosystems where organic matter is built up in large quantities and offers ideal biotic conditions to sustain considerable aquatic population (Boominathan, Subhash chandran, Ramachandra, 2008; Rao, Suresh, 2002). Estuaries and surrounding areas are transitory places where the landscapes change from land to sea and water quality from fresh to salty. Although influenced by the tides estuaries are protected from the ocean waves, winds and storms by reefs , barrier islands and land, mud or sand that define an estuaries seaward boundary (Ramachandra, Bharath, Vinay, 2018; Ramachandra, Bharath, Vinay, 2018). More than 200 rivers flow towards the west coast and develop as estuaries before joining the Arabian Sea.

Fresh water influx and density difference between the two merging water entities, a constant replenishment of nutrients and versatility in their structure make it a nursery ground for many marine organisms (Ramachandra, Vinay, Subashchandran, 2018). Diverse habitats that are found in and around estuaries can be grouped as shallow open waters, fresh water and salt marshes, sandy beaches, mud and sand flats, rocky shores, mangrove forests, river deltas, tidal ponds and sea grass beds. The estuarine ecosystem is essential for the survival of birds, mammals, fish, etc., which depend on the ecosystem for living, feed and reproduction. Many marine organisms, including commercially valuable fish species depend on estuaries at some stage during their development (Bhat, Subhashchandran, Ramachandra, 2010; Ramachandra, Bharath, Vinay, 2018; Ramachandra, Bharath, Subashchandran, et al., 2018; Wilson, Farber, 2005). Estuaries are the year round home for many species (oysters), while other species (salmon and shrimp) move in and out of estuaries on a seasonal basis for reproduction and growth (Wilson, Farber, 2005).

Estuaries and inlets serve as places of relative shelter that also provided staging areas for harvesting food and fiber (Wilson, Farber, 2005). Estuaries supports the livelihood to rural communities with the provision of a variety of living and non-living resources, which offer opportunities for employment, income, amenities and pleasure to the local people (Boominathan, Subhash chandran, Ramachandra, 2008; Thomson, 2003). Fishing is one of the major economic activities of the rural coastal communities (Anoop, Suryaprakash, Umesh, et al., 2008; Bhat, Subhashchandran, Ramachandra, 2010; Thomson, 2003). Apart from these direct tangible flows of economic benefits, estuaries also provide a variety of indirect services to local communities and to the rest of the world which enhance the economic significance of these systems manifold. The capacity of estuaries to regulate various gases, climate, water currents and flow, soil erosion and sedimentation, retention and soil formation, nutrient cycling, waste treatment, pollination and thereby control the various biological processes is well recognized. Moreover, estuaries supply various kinds of recreation services and act as the primary pool of genetic resources. In fact, these diverse ecosystem functions along with the direct flow of benefits through the supply of various goods and services make these systems valuable to humanity. These services are enjoyed by human users almost free of cost or at a price much below the cost of acquiring alternate but similar services (Boominathan, Subhash chandran, Ramachandra, 2008; Ramachandra, Soman, Ashwath, et al., 2017; Thomson, 2003).

The estuaries are also the repositories of mangroves biodiversity which serve as a wall for the coastline apart from providing numerous other benefits. Mangroves are salt tolerant forest ecosystems found mainly in tropical and sub-tropical intertidal regions (Hirway, Goswami, 2007; Kathiresan, Narayanasamy, 2005; Bhat, Subhashchandran, Ramachandra, 2010) where they may receive organic materials from estuarine or oceanic ecosystems. The presence of mangroves enriches various forms of living organisms and ensures smooth delivery of various ecosystem services to humanity at large. These rich ecosystems provide a wide range of ecological and economic products and services, and also support a variety of other coastal and marine ecosystems, which again provide several economic and ecological benefits (Hirway, Goswami, 2007; Kathiresan, Narayanasamy, 2005; Prakash, Subhashchandran, Ramachandra, 2010). Mangroves supply forestry products (firewood, charcoal, timber, honey etc.) and fishery products (fish, prawn, crab, mollusk etc.). Due to high calorific values, mangrove twigs are used for making charcoal and firewood. Mangrove swamps act as traps for the sediments, and sink for the nutrients. The root systems of the plants keep the substrate firm, and thus contribute to a lasting stability of the coast (Kathiresan, Narayanasamy, 2005).

The economic valuation of ecosystem goods and services (Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997) highlights the annual value of the ecosystem services of the terrestrial and aquatic biomes of the world in the range of US$16–54 trillion with an estimated average of US$33 trillion. This value was found to be 1.8 times higher than the current gross national product (GNP) value for the world. About 62% of the estimated values of ecosystem services were found to be contributed by the marine ecosystems, while about 38% of the estimated values were found to be contributed by the terrestrial ecosystems, mainly from the forests and wetlands. A detailed socio-economic valuation of various direct, indirect and non-use values of Kali estuary in Karnataka and Cochin estuary in Kerala (Thomson, 2003) revealed aggregate value from the traditional, modern, recreational and non-use values was found to be Rs. 44380 lakhs (ten lakhs is equivalent to one million) for Cochin estuary while for Kali estuary it was found to be Rs. 1163.56 lakhs.

The mangrove vegetation also plays a vital role in the coastal resources, thereby contributing an important part towards our socio-economic development. Mangroves are sources of highly valued commercial products and fishery resources and also as sites for developing a burgeoning eco-tourism (Kathiresan, Narayanasamy, 2005; Prakash, Subhashchandran, Ramachandra, 2010). The biodiversity protected and supported by mangroves include a wide range of creatures, ranging from bacteria, and fungi, insects, a variety of fish, prawns, shrimps, etc., to a variety of birds along with a variety of flora – sea weeds, small plants and creepers (Hirway, Goswami, 2007). The damage cost avoided due to mangroves in villages was estimated as 116.28 US$/household while the land accretion function was estimated to be 983795.7 US$ over a period of 111 years. The overall value of benefits (use and non-us values) generated by mangroves in Gujarat was about Rs 2246.93 crores per year (Hirway, Goswami, 2007). The total economic value of the mangrove ecosystem in Rekawa lagoon, Srilanka show the value generated per hectare per year ass 18570 Rs/ha/year (lagoon fishery), 34,500 Rs/ha/year (coastal fishery) and 1500 Rs/ha/year respectively (Gunawardena, Rowan, 2004). The services such as buffer against storm and erosion control of mangroves was calculated using replacement cost approach and reached the value of 21000 Rs/ha/year. The existence bequest and option value to local community was estimated as 181.2 Rs/ha/year. The Net Present Value of 400 ha mangrove area of Tha Po village by calculating the direct benefit through wood and non-timber forest products and indirect benefits like off-shore fishery linkages and coastline protection. Based on the estimated net income from mangrove products, the total annual value of the 400 ha of mangrove forest was $88 per ha. and the annualized value of coastline protection was estimated using replacement coast method and the value was $3697 /ha. The net present value for 20 year period with 15 % discount rate was obtained as US $ 632.27 /ha and including indirect use values it was US$ 27,264 - 21,610 /ha. (Sathirathai, Barbier, 2001). Economic analysis of twelve year mangrove plantation had carried out in the Gazy bay in Kenya show the net value of extractable wood products from the plantation at US$ 379.17/ha/yr. For non-extractable products, the net value ranged from US$ 44.42/ha/yr in carbon sequestration to US$ 770.23/ha/yr for research and education. The total economic value of 12 yrs old Rhizophora plantation is therefore US$2902.87/ha/yr. An economic valuation mangrove resource utilization study of Gaz and Hara delta located in South Iran computed the total economic value as 10000-20000 US$/ha/year (Ghasemi, Mola-Hoveizeh, Zakaria, et al., 2012).

The economic valuation of Aghanashini estuary based on bivalve production (Boominathan, Subhash chandran, Ramachandra, 2008) reveals the revenue generation of 57.8 million per year, fishing in open estuary generates 497990 man days of work and the per capita income was 56695 Rs annually (Bhat, Subhashchandran, Ramachandra, 2010). The integrated value of goods - tangible goods like fish, salt, shrimp culture, bivalve food, mangrove fodder, lime and sand mining estimated for the estuary from 4801 ha was Rs.142.98 Crore/year (Note: One crore: 10 million). The tangible goods value Rs /ha/year was 2,97,813 (Prakash, Subhashchandran, Ramachandra, 2010). The NPV of total direct benefit of Ashtamudi estuary was about 1928 million Rs (Anoop, Suryaprakash, Umesh, et al., 2008). The clam bed is located in the Aghanashini estuary at Tadri and this bed comprises of Meretrix meretrix and Mretrix casta. The adjacent bed is about 5 kms from the barmouth and extends from opp. Betkuli to near Mirjan and covers an area of 225 ha. Meretrix casta and Villorita cyprinoides occur in this bed. A third bed is located in the centre of the estuary in Mirjan-Hegde area and it contains only V. cyprinoides. Meretrix casta and Villorita cyprinoides occur in this bed. The total annual production is 755 t and M.casta constitutes more than 60%. The production of V. cyprinoides is only 5 t. The estimated annual effort in man days is 23000 and fishing is by handpicking. Shell deposits are exploited about 7600 tons annually from the Tadri area and utilized for industrial purposes. Mining of mollusc shells is a flourishing business in Tadadi village, where shells worth about Rs.40-50 million are gathered and transported to far away cities for making poultry feed and for many other industrial uses (Bhat, Subhashchandran, Ramachandra, 2010).

1.1 Ecosystem goods and services: Ecosystem provides various vital benefits such as food; soil production, erosion and control; climate regulation; water purification; bioenergy, etc. these benefits and services are referred to as ‘ecosystem services’ and are very crucial for the survival of humans and other organisms on the earth. The ecosystems, if in a good condition perform functions which are of bio-geophysical in nature. These functions result in the flow of various services and benefits for humans and their society (Ramachandra, Soman, Ashwath, et al., 2017; MEA, 2005). Ecosystem functions can be defined as ‘the capacity of natural processes and components to provide goods and services that satisfy human needs, directly or indirectly’ (de Groot, Vander Meer, 2010; MEA, 2005). Millennium Ecosystem Assessment defines ecosystem services as the benefits people obtain from ecosystems. It includes provisioning services such as food and water, regulating services such as flood and disease control, cultural services such as spiritual, recreational and cultural benefits, and supporting services such as nutrient cycling that maintains the conditions for life on earth (MEA, 2005). The ecosystem goods and services are distributed (Fischlin, Midgley, Price, et al., 2007; Hassan, Scholes, Ash, 2005; MEA, 2005; Ramachandra, Soman, Ashwath, et al., 2017; Wilson, Farber, 2005) into four different categories as (i) provisioning services (Table 1), (ii) regulating services (Table 2), (iii) supporting services (Table 3) and (iv) cultural services (Table 4). 

Table 1: Provisioning services provided by the estuaries

Provisioning Services	Provision of natural resources and raw materials
Water supply	Filtering, retention, and storage of water	Provision of potable water and water purification Medium for transportation and ports Provision for irrigation and industrial use
Food	Edible plants and animals Arable land	Hunting, fishing, crops, grazing, and aquaculture
Raw materials	Building and manufacturing	Lumber, skins, plant fibers, oils, dyes, etc.
	Fuel and energy	Fuel wood and organic matter
	Fodder and fertilizer	Leaf litter, salt hay, excrements, etc.
Genetic resources	Genetic resources	Variety of gene pools in fish species
Medicinal and plant resources	Biological and chemical substances for use in agriculture and human treatment	Medicines and pest control chemicals obtained from estuarine dependent species
Ornamental resources	Resources for fashion, handicraft, jewelry, pets, worship, decoration, and souvenirs	Shells used as jewelry Dried grasses

Table 2: Regulating services provided by the estuaries

Regulating services	Maintenance of essential ecological processes and life support systems
Gas regulation	Regulation of the chemical composition of the atmosphere and oceans	Biotic sequestration of CO2 Vegetative absorption of VOCs
Climate regulation	Regulation of local and global energy balance and hydrological cycle, and other biologically mediated climate processes	Direct influence of land cover on temperature, precipitation, wind, humidity, etc.
Disturbance regulation	Dampening of environmental fluctuations/disturbance	Storm protection (e.g., by barrier islands) Flood protection (e.g., by wetlands and forests)
Soil retention	Erosion control and sediment retention	Prevention of soil loss by wind, wave action, runoff, or other removal processes from wetlands and barrier islands
Waste Assimilation	Removal or breakdown of nutrients and compounds	Pollution detoxification and sequestration Water purification

Table 3: Supporting services provided by the estuaries

Supporting services	Ecosystem structures and functions that are essential to the delivery of ecosystem services
Nutrient cycling	Storage, processing, and acquisition of nutrients	Net Primary Productivity
Soil formation	Capture of sediments and accumulation of organic matter	Formation of wetlands substrate and soils
Biological regulation and Biodiversity	Species interactions, including pollination	Control of pests and diseases, Reduction of herbivory, Pollination of wetlands plants
Habitat	The physical place where organisms reside	Refugium for resident and migratory species, Spawning and nursery grounds for shrimp and other fish
Hydrological cycle	Movement and storage of H2O through the biosphere	Aquifer recharge Maintain salinity gradients

Table 4 : Cultural services provided by the estuaries

Cultural Services	Enhance emotional, psychological and cognitive well being
Recreation	Opportunities for rest and enjoyment	Ecotourism, bird watching, outdoor sports, beach going, fishing, etc.
Aesthetic	Enjoyment of landscape and its elements	Coastal beaches and wetlands, added value to coastal housing Clean water
Science and education	Development of knowledge	A “natural field laboratory” for understanding coastal biological and physical processes
Spiritual and historic	Spiritual or historic information	Use of estuaries as motif in books, film, painting, folklore, national symbols, architecture, advertising, etc.
		Natural features with religious or historic

Estuarine and coastal ecosystems are the vulnerable natural systems globally (Barbier, Hacker, Kennedy, 2011) with the intense anthropogenic stress. The population and development pressures that estuarine areas are now experiencing raise significant challenges for planners and decision makers (Wilson, Farber, 2005). The deterioration due to human activities is severe and increasing; 50% of salt marshes, 35% of mangroves, 30% of coral reefs, and 29% of sea grasses are either lost or degraded worldwide (MEA, 2005). The loss of biodiversity, ecosystem functions, and coastal vegetation in estuarine and coastal ecosystems have contributed to biological invasions, declining water quality, and decreased coastal protection from flooding and storm events (Barbier, Hacker, Kennedy, 2011). There are numerous alternative uses of ecosystem functions and services. To choose from among these competing options, it is important to know not only what ecosystem goods and services will be affected but also what they are actually worth to different members of society (Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997). Efforts to assess and quantify all the benefits associated with coastal ecosystem goods and services, would aid in the policy and managerial decisions in favor of environmentally prudent practices (Barbier, Hacker, Kennedy, 2011). Economic valuation helps to compare the real costs and benefits of ecosystem use and degradation, and allows more balanced decision-making concerning the protection and renovation versus degradation of wetlands. This facilitates optimal decision-making which maximizes societal welfare (Turpie, Lannas, Scovronik, et al., 2010; Ramachandra, Setturu, Rajan, 2017; Ramachandra, Rajinikanth, 2003; Ramachandra, Kiran, Ahalya, 2002). Figure 1 illustrate an integrated framework for assessing the ecosystem goods and services considering a limited number of ecosystem functions which, in turn provide the goods and services that are valued by humans (Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; MEA, 2005; Ramachandra, Soman, Ashwath, et al., 2017). The ecosystem functions can be broadly classified into four different functions namely – regulation, production, habitat and information. The value of the ecosystem functions, goods and services can be roughly divided into three types – ecological (determined by the integrity of the regulation and habitat functions), socio-cultural (identifies vital environmental functions, physical and mental health, education, cultural diversity and identity (heritage value), freedom and spiritual values) (Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; MEA, 2005; Ramachandra, Soman, Ashwath, et al., 2017) and economic values (willing to give up in other goods and services in order to obtain a good, service, or state of the world) (Ramachandra, Rajinikanth, 2003; Ramachandra, Kiran, Ahalya, 2002; Ramachandra, Setturu, Rajan, 2017; Ramachandra, Soman, Ashwath, et al., 2017; Turpie, Lannas, Scovronik, et al., 2010).

Figure 1: Assessment of ecosystem goods and services

1.2 Total Economic Value (TEV) Framework: Figure 2 outlines the framework for valuation of the total economic values (TEV), which is the sum of all the benefits that are attributable to the estuarine ecosystem (UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011). The total economic value is composed of (i) use value (UV) and (ii) non-use value (NUV). Use value to humans consists of direct (the tangible or physical aspects of such resources, which can either undergo physical processing or provide direct (personal) utility or satisfaction and which have direct market prices for quantification (Ramachandra, Soman, Ashwath, et al., 2017; UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011), indirect (consist of the various functions that a natural system may provide, such as shoreline protection functions, carbon sequestration, and nutrient or contaminant retention (UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011).This is related to the change in the value of production or consumption of the activity or property that it is protecting or supporting) and option value (a special category of value, which arises because of an individual’s uncertainty about his or her future demand for a specific resource, or the availability of this resource in the future (UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011) and often considered as a “use” value since it still relates to future direct or indirect use of the resource (Barbier, Hacker, Kennedy, 2011; Ramachandra, Soman, Ashwath, et al., 2017). Quasi-option value is related to option value such that there is still willingness to pay by the individual for the preservation of the resource, but instead of worrying about its future use, the preservation is for the value that it can presently provide (UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011). Direct-use values can be consumptive or non-consumptive and are commonly derived from goods and services by the inhabitants of the ecosystem whereas Indirect-use values are those that are more functional, the benefits of which often extend away from the ecosystem itself and are not consumed. Figure 2 outlines an economic valuation approach to valuing estuarine ecosystems. Non-use values of an ecosystem are bequest subset of non-use value that results from an individuals’ willingness to pay for the preservation or conservation of a resource so that future generations will still be able to reap its benefits (Ramachandra, Soman, Ashwath, et al., 2017; UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011) and existence values related to aesthetic, cultural, and moral aspects that a resource may have in that it is the value that an individual places on the resource because of the satisfaction that he or she derives from merely knowing that the resource, ecosystem or species exists, regardless of whether it will be used or not (UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011).

Figure 2: Framework for economic valuation of estuarine ecosystems

1.3 Techniques for quantification of ecosystem goods and services: The economic valuation methods for ecosystem goods and services are broadly grouped into four basic types – (i) direct market valuation (use of market price to value the resources that are marketed and can be used directly and indirectly (UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011). The values of both extractive and non-extractive uses are based on market price (accounting price), which can be quantified and monetized from the direct use of the coastal ecosystem (ii) Indirect market valuation (assessing the values can be used to establish the Willingness To Pay (WTP) or Willingness To Accept compensation (WTA) for the availability or loss of these services (Barbier, Hacker, Kennedy, 2011; Ramachandra, Soman, Ashwath, et al., 2017). This includes various techniques like Avoided Cost (AC) method, Replacement Cost (RC) method, Factor Income (FI) method, Hedonic Pricing (HP) method and Travel Cost (TC) method (Barbier, Hacker, Kennedy, 2011; Costanza, Folke, 1997; Costanza, d’Arge, de Groot, 1997; Ramachandra, Soman, Ashwath, et al., 2017), (iii) Contingent valuation (economic values for non–marketed goods, such as environmental assets, amenities, and services are estimated through surveys to ascertain respondents’ preferences regarding an increase or decrease in the level of environmental quality (UNEP/GEF, 2007; UNEP, 2013; TEEB, 2011). The preferences are valued through surveys to ascertain willing to pay for the preservation or improvement of a certain resource or environment or to accept payment for doing away with said resources or environment, (iv) group valuation (based on principles of deliberative democracy and the assumption that public decision making should result, not from the aggregation of separately measured individual preferences, but from open public debate) (Barbier, Hacker, Kennedy, 2011; Costanza, Folke, 1997; Costanza, d’Arge, de Groot, 1997; Ramachandra, Soman, Ashwath, et al., 2017) and Benefit transfer method (of using values estimated for an alternative policy context or site as a basis for estimating a value for the policy context or site in question (Barbier, Hacker, Kennedy, 2011; Ramachandra, Soman, Ashwath, et al., 2017) Benefit transfer technique is an easy approach involving (i) identifying resources or services to be valued, (ii) identifying relevant existing studies, (iii) evaluating applicability and (iv) conducting the benefit transfer. This method is used for damage assessment, where there is a need of existing estimate of value of the natural resource or services provided by the resource. The main objective of the current communication is to estimate the total economic value of Aghnashini estuarine ecosystem of Uttara Kannada in order to enhance natural resource productivity through prudent managment. This includes (i) estimating value of provisioning services; and (ii) estimating the value of indirect products and services of the estuarine ecosystem such as regulating, supporting and information services.

 

2.0 MATERIALS AND METHOD

2.1 Study Area: The Uttara Kannada district lies in the mid-western part of Karnataka state between 7409' to 75010' E and 13055' to 15031' N extending over an area of 10,291 sq.km (figure 3). It extends from north south to a maximum of 180 km, and from west to east a maximum width of 110 km. It is surrounded by Belgaum district and Goa territory in the north, Dharwad in the east, Shimoga and parts of Daskshina Kannada in the south and the Arabian Sea to the west. Uttara Kannada district is one of the northernmost districts in Karnataka State (Ramachandra, Vinay, Bharath, et al., 2018; Ramachandra, Bharath, Vinay, 2018; Ramachandra, Sincy, Asulabha, et al., 2018). The topography of the region can be divided into three distinct zones. The coastal zone, comprising of a narrow strip of the coastline, is relatively flat and starts sloping gently upwards towards the east (Deepthi, Subashchandran, Joshi, et al., 2017). The ridge zone abruptly rises from the coastal strip, is much more rugged and is a part of the main range of the Western Ghats. The coastal Uttara Kannada consists of five taluks namely Karwar, Ankola, Kumta, Honnavar and Bhatkal from north to south and has a total area of 3300 sq.km. This study describes the ecological goods and services obtained from the Aghanashini estuary in Uttara Kannada district (Ramachandra, Bharath, Subashchandran, et al., 2018; Ramachandra, Vinay, Subashchandran, 2018).

Figure 3: Aghanashini estuary, Uttara Kannada district, Karnataka, India

Aghanashini Estuary - Aghanashini River has its source in the forest clad village Manjguni situated at an altitude of about 600 m in the central Western Ghats. Running its course of about 121 km, winding through gorges flanked with evergreen forests and valleys lush with spice gardens and rice fields, the river widens into an estuary covering about 4801 ha before its confluence with the Arabian Sea in the west coast between the villages Aghanashini in the south and Tadadi in the north, lies between 14.391° to 14.585° N and 74.304° to 74.516° E of Kumta taluk (Deepthi, Subashchandran, Joshi, et al., 2017) in the Uttara Kannada district of central west coast in the Karnataka State of India (Figure 3). All along its estuarine banks and few of the tiny islands are villages whose inhabitants mainly are traditionally dependent on agriculture and fisheries. There are about 21 villages of Kumta taluk situated on the estuarine banks.

 

2.2 Methods: The secondary data was obtained from various sources for assessing the resource availability and consumption scenarios in the five estuaries. Field survey were carried out regarding the fish resources, sand mining and salt production in the estuaries. This involved actual measurements (quantifications) and discussions with the local people. The secondary data regarding the ecological functions of the estuaries was collected from Central Marine Fisheries Research Institute (CMFRI) centres of Cochin and Karwar; Department of Marine Biology, Karnatak University, Karwar; Cochin University of Science and Technology, Biodiversity portal (Sahyadri, 2018). The socio-economic data related to the coastal taluks including the villages around the estuaries were obtained from 2001 Census Report, Govt. of India; District Administrative Reports, Govt. of Karnataka. The data regarding the production of Gazani paddy and Coconut in the estuarine region was obtained from Karnataka State Horticulture Department. The direct and indirect values obtained from the estuaries were calculated.

Table 5: Economic values assigned to different indirect ecosystem services

FUNCTION	COUNTRY/ REGION	TECHNIQUE USED	UNIT (Rs/Hectare)	References
Regulating services
Erosion control	Gujarat	Damage cost avoided	137606	Hirway, Goswami, 2007; Prakash, Subhashchandran, Ramachandra, 2010
Flood control	Srilanka	Replacement cost	158249.67	Barbier, Hacker, Kennedy, 2011; Gunawardena, Rowan, 2004; Sathirathai, Barbier, 2001;
Storm protection	Srilanka	Replacement cost	45000	Kathiresan, Narayanasamy, 2005; de Groot, Vander Meer, 2010
Nutrient retention	Orissa	Replacement cost	11034.5	Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Disturbance regulation	Global	Benefit transfer	25515	Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Waste treatment	Global	Benefit transfer	301320	Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997
Nutrient cycling	Global	Benefit transfer	949500	Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Carbon sequestration	Ashtamudi estuary, Kerala	Damage cost avoided	9110.2	Anoop, Suryaprakash, Umesh, et al., 2008; Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Gas regulation	Global	Benefit transfer	9600	Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; Fischlin, Midgley, Price, et al., 2007
Climate regulation	Global	Benefit transfer	4800	Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; Fischlin, Midgley, Price, et al., 2007
Oxygen provision	Global	Benefit transfer	5280	Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; Fischlin, Midgley, Price, et al., 2007
water regulation	Global	Benefit transfer	209088	Barbier, Hacker, Kennedy, 2011; Fischlin, Midgley, Price, et al., 2007
water supply	Global	Benefit transfer	145920	Barbier, Hacker, Kennedy, 2011; Fischlin, Midgley, Price, et al., 2007
Ground water recharging	Global	Benefit transfer	192000	de Groot, Vander Meer, 2010; Fischlin, Midgley, Price, et al., 2007; Barbier, Hacker, Kennedy, 2011; Hassan, Scholes, Ash, 2005; MEA, 2005
Natural hazard mitigation	Global	Benefit transfer	9600	Ramachandra, Kiran, Ahalya, 2002; Ramachandra, Rajinikanth, 2003; UNEP, 2013; UNEP/GEF, 2007
Supporting functions (Sahyadri, 2018)
Habitat/refugia	Global	Benefit transfer	5895	Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Breeding ground and Nursery	Thailand	Benefit transfer	5271.3	Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Biodiversity	Global	Benefit transfer	216000	Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Information Functions (Sahyadri, 2018)
Recreation	Global	Benefit transfer	17145	Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; de Groot, Vander Meer, 2010
Cultural and artistic	Global	Benefit transfer	1305	Bann, 2003; Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; UNEP, 2013; NEP/GEF, 2007; TEEB, 2011;
Aesthetic	Global	Benefit transfer	100	Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997
Science and Education	Kenya	Research funds	34660.35	Bann, 2003; Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; UNEP, 2013; NEP/GEF, 2007; TEEB, 2011

 

Market valuation technique was employed for valuing the goods and services having direct market prices such as fishing, gazani (salt tolerant) paddy cultivation, timber and fodder obtained from the mangrove vegetation, aquaculture, sand and lime shell mining, navigation, ferry services and port activities. The market price values were assigned to these goods based on the interaction with the locals residing in that region. The gross revenues obtained from these resources were obtained as per the equation 1.

Net benefit from the fisheries = Total fish production in the estuary (tons) x Price per ton

Net income from mining/agriculture products = Σ (P Q) ……1

Where, P = price of the product; Q = quantity of the product

Besides providing the direct use value goods, the estuaries also provide various other important benefits such as climate regulation, shoreline stabilization, natural hazard mitigation, habitat and refugia for various organisms, nutrient circulation, recreation and aesthetic benefits, etc. CVM (Contingent Valuation Method) was adapted to survey indirect values obtained from an ecosystem which is based on the people’s Willingness to Pay (WTP) for it. For the current valuation study, the values for the indirect ecosystem services were adapted from the published literatures (Ramachandra, Soman, Ashwath, et al., 2017; Bann, 2003; Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; UNEP, 2013; NEP/GEF, 2007; TEEB, 2011). The values were given in US dollars which were converted into Indian Rupees (INR) given in Table.5.

 

The direct, indirect and recreational benefits obtained from the estuaries were summed up together to obtain the Total Economic Values (TEV) of the ecosystem as per the equation 2. This value is divided by the total geographical area of the estuary to arrive at the per hectare value of the estuary as a natural resource. These economic values can be considered as underestimates as the natural ecosystems are much more worth in terms of the benefits they provide. The valuation of natural resources is useful for policy formulations and decision making.

Total Economic Value = Direct use value +Indirect use Value …..2

 

3.0 RESULT S AND DISCUSSION

The present study focused on accounting the economic value of Aghanashini estuary located in the Uttara Kannada district of Karnataka State. The estuary has been providing a variety of living and non-living resources to the local communities which offer employment, income, amenities and pleasure. Apart from the direct benefits these ecosystem provides many indirect benefits to surrounding communities. However, the decision makers have not considered the significance of this precious ecosystem evident from the unplanned developmental activities. The current tudy is an attempt to highlight the economic importance of the estuarine ecosystem in Uttara Kannada.

3.1 Demarcation of study area and characterization of ecosystem goods and services from the estuarine ecosystem:
The Aghanashini estuary is the largest estuary in Uttara Kannada having 4801 ha of total expanse and it includes the 101.6 ha of mangrove area. Aghanashini supports 64709 peoples (6000-7500 families). Major goods and services from the estuaries were compiled through field investigations, literature survey and discussion with local persons. These goods and services are then classified as per the standard protocol (Ramachandra, Soman, Ashwath, et al., 2017; Bann, 2003; Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; MEA, 2005) as Provisioning Services, Regulating Services, Supporting Services and Information Services.

 

3.2 Provisioning services from Uttara Kannada estuaries

Provisioning services are estuarine fishery including the fish, finfish, shellfish and aquaculture, mining products, mangrove resources, salt production, agriculture including the saline paddy and coconut and water transport activities like ferry services, navigation and the port activities. In order to calculate the total value, the market price approach was used.

3.2.1 Estuarine fishery: The fishery sector contributes the major livelihood options of the estuarine dependent communities in the coastal villages. It includes the common estuarine fishes, clam, oyster, mussels, bivalves, prawns and aquaculture. The market price of fish and quantity obtained from each category of fish resources are given in the table 6.1. Aghanashini estuary provides the 92.93% of the income from estuarine fisheries in Uttara Kannada. The annual revenue is 4.12 billion Rs. The 94.64 percentage (3.9 billion) revenue comes from aquaculture activities in the estuarine belt. Aghanashini estuary fishes contribute 120.7 million Rs. with 2.93%. Aghanashini estuarine villages have been benefited by the bivalve collection with a total annual income of 57 million Rs. The total revenue from shell fish collection in this estuary is 73.5 million Rs. comprising of bivalves, clams, oyster, mussels and other molluscans.

Table 6.1: Estuarine fisheries value

Item	Total fish catch - ton	Price Rs /ton	Income Rs /year
Fishes	12076	150000	120,762,000
Bivalves	2851	200000	57,018,710
Clam	76	15000	11,325,000
Oyster	0.642	200000	128,450
Mussels	28	120000	3,360,000
Other molluscs	14	120000	1,673,700
Crab	56	325000	18,200,000
Prawns	38	250000	7,665,000
Aquaculture	8680	450000	3,906,000,000
Total – Rs.			4,126,132,860

 

3.2.2 Agriculture products: The estuarine belt of Uttara Kannada support saline tolerant paddy (gazani) and coconut cultivation. Total quantity of production and market price of coconut and paddy is given in the table 6.2. The returns from gazani paddy are highest in the Aghanashini estuarine region with a value of 43.9 million Rs.. The total agricultural production from the estuary is 49.5 million Rs. and it contributes 29.64% of the district total. 

Table 6.2: Goods from Estuarine Agriculture

Item	Total production (ton)	Price Rs/ton	Income Rs/year
Gazani paddy	2443	18000	43,977,600
Coconut	62	90000	5,614,776
Total– Rs.			49,592,376

 

3.2.3 Mining products: Mining and dredging activities are happening in the estuary of Uttara Kannada in significant level. Amount dredged and the price of unit quantity is given in the table 6.3.and these are the livelihood options for many poor people in this region. This shows it occurs in higher degree in Aghanashini. The net returns from the region are 1.2 billion Rs. annually; out of these 99.26% comes from lime shell collection only.

Table 6.3: Estimation of Revenue from Mining activities

Item	Quantity extracted	Rate (Rs/unit)	Income (Rs/year)
Sand (Cu.m)	17308	400	6,923,077
Lime shell (ton)	80000	15000	1,200,000,000
Silt(Cu.m)	9855	200	1,971,000
Total– Rs.			1,208,894,077

 

3.2.4 Mangrove products: Mangrove forest is being used by the local inhabitants as fodder for live stocks and timber for fire wood needs and construction activities. Table 6.4 lists the mangrove resources with market price and quantity. The Aghanashini contributes 31% of total mangrove product harvest of Uttara Kannada; the income is 5.4 million Rs/ year.

Table 6.4: Estimation of Net income from Mangrove product harvesting

Item	Quantity produced -ton	Price (Rs/ton)	Net income (Rs/Yr)
Fodder	7200	600	4,320,000
Timber	215	150	32,199
Charcoal	64	150	9,660
Thatch	322	2000	643,973
Fish poison	6	1000	6,000
Medicine	24	18000	432,000
Total – Rs.			5,443,831

 

3.2.5 Salt from estuaries: Table 6.5 shows that salt production in the Aghanashini estuary of Uttara Kannada, which is about 5 million Rs. per year. Salt making is a traditional enterprise associated with some of the villages close to Gokarna, Aghanashini where salt pans annually produce Rs.30-40 million Rs. worth of salt (Bhat, Subhashchandran, Ramachandra, 2010).

Table 6.5: Salt production in the estuarine catchment

Quantity produced (ton)	Rate Rs/ton	Value generated Rs/year
10000	5000	50,000,000

3.2.6 Transport:  Table 6.6 gives the revenue generated from ferry services, navigation and port activities in the estuarine waters. The net income from water transport activities is highest in Aghanashini (52%). The value from ferry services is about 1.6 million Rs. Per year.

Table 6.6: Revenue from Water transport and Port activities

Activity		Value generated Rs/year
Ferry services		200,000
Navigation		80,000
Port activities		1,418,000
Total – Rs.	1,698,000

 

3.2.7 Total provisioning services: Provisioning services quantification through the compilation of all direct benefits for each estuary is given in table 7. Aghanashini make up the 79.5% (5.45 billion Rs. annually) of the district total and the value per hectare of estuary is 11,35,847 Rs. per hectare per year (Aghanashini).

Table 7: Provisioning services from Estuaries, Uttara Kannada

Details	Aghanashini
Area	4801 ha
Fishery	4,126,132,860
Agriculture	49,592,376
Mining activities	1,208,894,077
Mangrove product harvest	4,806,298
Water transport	1,698,000
Salt production	50,000,000
Total Value (Rs/Year)	5,453,199,811
Production (Rs/ha/year)	1,135,847

3.3 Indirect uses
The indirect uses of estuarine ecosystem consist of the Regulating services, Supporting services and Information services Bann, 2003; Barbier, Hacker, Kennedy, 2011; Costanza, d’Arge, de Groot, 1997; Costanza, Folke, 1997; MEA, 2005; Ramachandra, Soman, Ashwath, et al., 2017; Sahyadri, 2018; TEEB, 2011; UNEP, 2013; NEP/GEF, 2007). Table 5 lists 23 indirect benefits provided by estuarine ecosystem. All these services are valued by taking the unit value of these benefits (Rs/ha/year) from other studies and adjusted according to the spatial and environmental conditions of our study region.

3.3.1 Regulating services: The regulating services of estuary ecosystem are coastal erosion control, Flood control, storm protection, carbon sequestration, disturbance regulation, gas regulation, climate regulation, water supply, waste treatment, nutrient retention and cycling, natural hazard mitigation, ground water recharging and oxygen provision. Table 8 gives the details of regulating services calculated considering the spatial extent of the estuary and unit value (Rs/ha/year). The regulating services value from total estuarine area is 8.81 billion Rs/ Year. This is mainly due to the higher mangrove cover and total area of these two estuaries. The regulating service value per hectare in Aghanashini is Rs. 2,055,250.

Table 8: Services and goods of estuaries

Services	Aghanashini
Coastal erosion control	13,980,762
Flood control	16,078,167
Storm protection	4,572,000
Nutrient retention	1,121,103
Disturbance regulation	2,592,324
Waste treatment	1,446,637,320
Nutrient cycling	4,558,549,500
Carbon sequestration	925,596
Gas regulation	46,089,600
Climate regulation	23,044,800
Oxygen provision	25,349,280
Water regulation	1,003,831,488
Water supply	700,561,920
Groundwater recharging	921,792,000
Natural hazard mitigation	46,089,600
Total Value Rs/Year	8,811,215,461
Production Rs/ha/year	1,835,288

 

3.3.2 Supporting services: The supporting services selected for economic valuation are Habitat/refugium function, Nursery and breeding ground, biodiversity. The estuarine ecosystem support and provide habitat for diverse flora and fauna, serving as a pool of biodiversity. The estuary and associated mangrove ecosystem and salt pans provide the platform and conditions for breeding and spawning of many marine and fresh water fishes. Table 9 reveals that the supporting service value of Aghanashini region, which accounts to the 82.935% with the total value of 9.34 billion/year. The value per hectare from Aghanashini is 1,946,030 Rs. towards supporting services.

Table 9: Supporting services from Estuaries in Uttara Kannada

Services	Aghanashini
Area	4801 ha
Primary production	8,252,265,720
Habitat/refugia	28,301,895
Breeding ground and Nursery	25,307,511
Biodiversity	1,037,016,000
Total Value (Rs/year)	9,342,891,126
Production (Rs/ha/year)	1,946,030

 

3.3.3 Information services: The information services include recreation, cultural and artistic information, science and education and the values are given in table 10.

Table 10: Information services from Estuaries in Uttara Kannada

Services	Aghanashini
Area	4801 ha
Recreation	82,313,145
Aesthetic information	6,265,305
Science and Education	480,100
Science and Education	332,808,680.70
Total value (Rs/year)	421,867,231
Production (Rs/ha/year)	87,871

Aghanashini contributes the highest percentage of information services (43%). These salt pans in this region are the visiting place of migratory birds during seasons. It adds to the aesthetic and recreational potential of Aghanashini. The total value of Aghanashini is 421 million Rs/Year with a per hectare value of 87,871 Rs.

3.4 Total economic value

Total economic value is the sum of all the four services given in Table11. Aghanashini estuary is the highly productive and comparatively intact ecosystem; therefore the total economic value is 62% of total district value. The value in Rs/year is 24.03 billion and the productivity per hectare is 5 million Rs/year. Provisioning service makes up the 23% of the total value. Information service share only 2% and regulating and supporting services are 37% and 39% respectively.

Table 11: Total Economic Value of Estuarine Ecosystem in Uttara Kannada

Goods and Services	Details	Aghanashini	Total (District)
	Total area (ha)	4801	10,591, 00
	Population	64709	14,36,847
Provisioning services	Total Rs/Year	5453199811	6858828735
	Production Rs/ha/year	1135847	1938457
	% contribution	23	17.82
Regulating Services	Total Rs/Year	8811215461	19390691963
	Production Rs/ha/year	1835288	8586037
	% contribution	37	50.37
Supportng services	Total Rs/Year	9342891126	11264961997
	Production Rs/ha/year	1946030	3143402
	% contribution	39	29.27
Information Services	Total Rs/Year	421867231	978291729
	Production Rs/ha/year	87871	371400
	% contribution	2	2.54
Total Economic Value	Total Rs/Year	24,029,173,629	38,492,774,424
	Production Rs/ha/year	5,005,035	3,634,480

 

4. CONCLUSION

Ecological systems play a fundamental role in supporting life and sustaining the natural reources. Most of the natural ecosystems are rapidly disappearing as a result of the pressure of population growth and economic development. In order to formulate sustainable natural resource use policy and measures, valuation of the uses of these ecosystems becomes essential, This will help resource managers deal with the effects of market failures, by measuring their cost to society, which otherwise are generally hidden from the traditional economic accounting. The present study provides an account of the resource potential of Aghanashini estuary of Uttara Kannada district, Karnataka state, India. Aghanashini estuary is the highly productive and comparatively intact ecosystem; the total economic value is 62% of total district value. The total economic value for Aghanashini is 24.02 billion Rs/ year and the annual value per hectare is 5 million Rs/ heactare/year. This highlights that estuaries of Uttara Kannada have been sustaining the economy of the district in a significant manner with the job potential. Majority of people living around the estuary earns livelihood from this estuaries. Decline in the environmental quality of these ecosystems necessitates the concerted effort to conserve the estuary in a sustainable manner with the active participation of native people. This also emphasizes the need for green GDP (Gross domestic product) with the accounting of ecosystem goods and services to ensure the sustainability of natural resources (water, energy, land, etc.).

 

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Specific criteria based on water birds : Aghanashini Estuary abode of diverse birds
Criteria 5		A wetland should support 20000 or more water birds		Aghanashini estuary supports more 45000 birds (40% are migrants)
Criteria 6		A wetland should support 1% of the individuals in a population of one species or subspecies of water bird		About 39 species have population >1% of the total population (of total sighted 130 species)

Bird diversity: Aghanashini estuary is remarkable for its bird fauna, with about 130 species recorded. About 40 per cent are migrants during winter. The estuary has several micro-habitats for birds, especially mudflats, mangroves, shallow marshes with reeds and grasses, deep open water, gazni rice fields etc. A bird species may use one or more such micro-habitats. January was noted as being the peak time for birds of the estuary, when the largest congregations happen. Aghanashini merits the status of a conservation reserve for birds for their sheer numbers and the ease with which they can be observed.

The birds can be grouped into six categories:

1. Large wading birds like herons, egrets, ibises and spoonbills: Two-thirds of them feed exclusively on fishes.
2. Probing shorebirds: This big group includes plovers, curlews, whimbrels, sandpipers, godwits, stints, ruffs, sanderlings, shanks, waterhens, jacanas, lapwings, stilts, moorhens, pratincoles, turnstones, avocets and curlews. In the Aghanashini estuarine area, 32 species were found, of which only 10 are resident birds.
3. Floating and diving birds: Ducks, grebes, cormorants, darters and teals of 11 species. Of these, four are residents and the rest migrants during winter. Whereas cormorants and darters are piscivorous, pintails, ducks and teals are herbivorous.
4. Aerially searching but water-dependent birds: Gulls, terns and kingfishers belong to this category. Of the 17 species noted, 10 are residents and the rest migrants.
5. Birds of prey: Kites, eagles, shikras, ospreys, owls and kestrels are birds of prey. Among the nine species found, five are residents and four are visitors.
6. Arboreal birds: Probably the largest group of diverse kinds, such as doves, cuckoos, robins, warblers, woodpeckers, flycatchers, parakeets, swallows, thrushes, orioles, sparrows, flowerpeckers, bush larks, shrikes, mynas, babblers, bulbuls, pipits, sunbirds, munias, coucals, wagtails, hoopoes, larks and ioras. Of the 49 species, only four are migrants, and the rest are local.

 

Estuary and Bird Diversity: Being meeting places of the land and rivers with the sea, estuaries are tremendously gifted areas with regard to their productivity, habitat diversity and richness of biodiversity. The world over, they are recognized as remarkable places for bird species. One of the important reasons for such recognition has been the variety of food resources available to meet the needs of birds, which require to feed frequently to maintain their high metabolic rates. Birds are known to congregate in places where food is plentiful (Hockey et al. 1992). As estuarine environments are favourable places for human settlements, birds specially adapted to humanized landscapes like crows, mynas, pigeons, parakeets, kites, drongos, flycatchers, bulbuls and babblers are commoner species in these areas. Because estuaries and the seashores are subjected to rising and receding tides, the intertidal areas are very favoured places for characteristic shorebirds. These include plovers, gulls, terns, sandpipers, turnstones, avocets, whimbrels, curlews, etc. They feed on intertidal invertebrates, which are exposed at low tide. Dugan et al. (2003) noted many shorebirds as feeding on insects, amphipods and isopods associated with algal mats deposited by waves on the beaches of California. Beach grooming (the practice of removing debris and seaweeds from sandy beaches) had adverse effects on shorebirds like plovers which feed on these organisms.

Dugan and Hubbard (2006) noticed that coastal armoring against rising sea levels indeed accelerated beach erosion and increased ecological impacts to sandy beach ecosystems on unprecedented scales. Mid- and upper-beach zone widths were reduced, with significant impacts on macro-invertebrates, foraging shorebirds and roosting gulls and seabirds on open beaches. In coastal and estuarine ecosystems, birds are often regarded as top predators, and fishes occupy intermediate trophic levels, both supported by large amounts of intertidal benthic macrofaunal prey. The high benthic biomass reflects extensive intertidal flats and fine sedimentary deposits. Such flats and sedimentary deposits are associated with tidal asymmetry and flocculation (Raffaelli and Hawkins 1996). As fine mud and silts provide a large surface area for accumulation of organic matter and microbial processes, intertidal mudflats are enabled to support a high invertebrate biomass, especially of deposit- and filter-feeding taxa (Fujii 2012). This benthic invertebrate biomass provides food for higher trophic levels, such as epibenthic crustaceans, fishes and shorebirds (ibid.). In north-west Europe, while migratory birds like the Brent goose, shelduck, pintail, oystercatcher, ringed plover, grey plover, bar-tailed and black-tailed godwits, curlew, redshank, knot, dunlin and sanderling are dependent on this habitat for food, the grey geese and whooper swan may utilize it for roosting (Davidson et al. 1991; Rehfisch et al. 2003). Many fishes and crustaceans also utilize the intertidal flats with the flood tide to feed. Flatfish, gobies and many other fishes, crabs and shrimps also move onto these intertidal flats to feed on the mobile epifauna and sedentary infauna (Elliott et al. 1998).

Shorebirds generally forage during the low tide and can be observed on beaches, intertidal mudflats, brackish wetlands, saltmarshes, etc. Water birds are those that entirely depend on wetlands for a variety of activities like foraging, nesting etc. Both shorebirds and water birds are important components of estuarine mudflats (Lane 1987; Norazlimi and Ramli 2015). Many winter migrant populations of shorebirds feed almost exclusively on intertidal benthic invertebrates of estuarine mudflats at low tide. The estuarine mudflats are also vital feeding habitats for resident bird populations (ibid.).

Characteristics of estuarine birds in relation to their feeding areas are of interest. The longer the leg, the deeper the mud or water depth in which the foraging birds stand. The long-legged waders (curlews, oystercatchers, etc.) walk into relatively deeper water compared with the shoter-legged turnstones, ringed plovers etc. Eddington et al. (1973) correlated the different bill lengths of wader groups to the depths of the soft substratum from which they can draw their prey. They found the bill lengths of curlews to be 11.5 cm, oystercatchers 7.3 cm, greenshanks 5.5 cm, redshanks 4.1 cm, dunlins 3.1 cm, turnstones 2.2 cm and ringed plovers 1.1 cm. The ringed plovers, short-legged and short-billed, find prey by surface picking whereas the turnstones, also short-billed, turned algal masses on the shore and turned stones to pick up the prey animals.

As increasing siltation on one side and rising sea level on the other are threatening to affect adversely estuarine mudflats and sandflats, most of the west coast estuaries of Karnataka, including Aghanashini, are being readied with defensive walls for flood protection. Considering the coastal geodynamic processes, the mudflats and sandflats of high biodiversity and bird richness are likely to suffer from more violent wave and tidal action on one side and maybe of high deposits of silt on them—both impacts likely to destroy the tidal flats and reduce the numbers of dependent birds. The study of estuarine birds, therefore, in relation to the dynamism of their habitats, rising human impacts, climatic change and conservation, requires greater efforts.

The bird diversity in Indian estuaries: Nisture and Pejaver (2002) recorded 205 species of bird from the 26 km long Thane Creek, an important bird area of the Mumbai coast. Recent station-wise detailed observations in the same creek covering only a 6 km stretch revealed 95 species (Chaudhari-Pachpande and Pejaver 2016). Of the nine IUCN Red Listed species from Aghanashini, only the black-headed ibis Threskiornis melanocephalus was common to both. Of these, 86 per cent were dependent on mangroves and mudflats. Verma et al. (2004) recorded 149 species of bird from the Mahul creek of Mumbai which is near the estuarine area of Bhayander and Naigaon (Ulhas estuary). Lad and Patil (2015) reported 131 bird species from the Ulhas estuary of Thane. Out of them 32 per cent were migratory and the rest residents. In the Bhatye estuary of Ratnagiri district in Maharashtra 113 species of bird were recorded. Of these only 16 species (14 per cent) were migratory and the rest residents or local migrants (Taware et al. 2012). Samant (1985) listed 121 species of bird occurring in the mangroves around Ratnagiri, Maharashtra. Pawar (2011) recorded 56 species of bird associated with the mangroves in the Uran estuary of Raigad district of Maharashtra coast.

 

THE BIRDS OF AGHANASHINI ESTUARY

Despite its avian diversity there has never been any exclusive study devoted to the birds of Aghanashini estuary. As part of a comprehensive study of the birds of Uttara Kannada district, Daniels (1988) studied the estuarine and coastal birds of the district. However, Daniels had personally communicated a list of 108 birds associated with Aghanashini estuary. We also referred to the Ph.D. thesis related to Aghanashini estuarine birds prepared by Roshmon, (2016) who also assisted in preparing the list of birds for the present work (Table 5.1). Other relevant information about these birds has been gathered from diverse sources and through field observations for the sake of this chapter. Annexure I lists the species wise number of birds sighted in the study region during the monthly survey for the period of 36 months and Annexure II lists the habitat wise sighting of species.

Table 5.1. Birds of Aghanashini estuary

S. N.	Scientific Name	Common Name	Habitat		Food	IUCN	IW Act-73	Migratory/ Resident
			Foraging	Roosting/Nesting
1	Phalacrocorax niger	Little  cormorant	Waterbodies	Mangroves	Fish		Sc IV	Resident
2	Phalacrocorax fuscicollis	Indian shag	Waterbodies	Mangroves	Fish		Sc IV	Resident
3	Anhinga melanogaster	Oriental darter	Waterbodies	Mangroves	Fish, large invertebrates	NT	Sc IV	Migratory
4	Ardea cinerea	Grey heron	Shallow water; marshes, mangroves	Mangroves	Fish, molluscs, crustaceans, insects, juvenile birds		Sc IV	Resident
5	Ardea alba	Great egret	Shallow water; marshes, mangroves, saltpans	Mangroves	Fish, crustaceans, insects		Sc IV	Resident
6	Egretta garzetta	Little egret	Shallow water, marshes, meadow, reeds	Mangroves	Small fish, crustaceans, bivalves, insects, chicks		Sc IV	Resident
7	Egretta intermedia	Intermediate egret	Shallow water, marshes, meadows, reeds	Mangroves	Fish, crustaceans, insects		Sc IV	Resident
8	Egretta gularis	Western reef egret	Shallow water	Mangroves	Fish, crustaceans, molluscs		Sc IV	Resident
9	Ardea purpurea	Purple heron	Reeds, marshes, mudflats, mangroves	Mangroves	Fish, nestling birds, crusta-ceans, snails		Sc IV	Migratory
10	Nycticorax nycticorax	Black- crowned night heron	Shallow water, marshes	Mangroves/reed beds	Fish, crustaceans, insects		Sc IV	Resident
11	Ardeola grayii	Indian pond heron	Marshy lands, shallow water	Mangroves	Fish, crustaceans, insects		Sc IV	Resident
12	Bubulcus ibis	Cattle egret	Marshy lands, shallow water, meadows	Mangroves	Insects, worms, eggs and chicks		Sc IV	Resident
13	Anastomus oscitans	Asian openbill	Shallow water, marshy areas	Mangroves	Bivalves, snails, insects, water snakes		Sc IV	Migratory
14	Leptoptilos javanicus	Lesser adjutant stork	Mangroves, saltpans, mudflats	Mangroves	Fish, large invertebrates	Vu	Sc IV	Resident
15	Threskiornis melanocephalus	Black-headed ibis	Marshes, shallow water	Mangroves	Fish, insects	NT	Sc IV	Resident/Migratory
16	Platalea leucorodia	Eurasian spoonbill (white spoonbill)	Shallow to deeper water; marshes, mangroves	Mangroves, reeds	Small fish, molluscs, crustaceans, worms, algae		Sc I	Migratory
17	Amaurornis phoenicurus	Whitebreasted waterhen	Shore, shall-ow water, reed beds		Insects, small fish, molluscs, worms, seeds		Sc IV	Resident
18	Hydrophasianus chirurgus	Pheasant-tailed jacana	Shallow water, reed marshes	On shallow water plants	Insects, invertebrates		Sc IV	Resident
19	Metopidius indicus	Bronze-winged jacana	Shallow water, reed marshes	On shallow water plants	Insects, snails and other invertebrates		Sc IV	Resident
20	Porphyrio porphyrio	Purple swamp-hen	Shallow water, reed marshes	On shallow water plants	Plant parts, seeds; also fish, molluscs, crustaceans, larvae, insects		Sc IV	Resident
21	Charadrius dubius	Little ringed plover	Intertidal zone, mudflats, fields, marshes		Shrimps, crustaceans, mussels, worms, insects		Sc IV	Migratory
22	Charadrius hiaticula	Common ringed plover	Mudflats, sandflats				Sc IV	Migratory
23	Pluvialis fulva	Pacific golden plover	Coastal fields, saltmarshes,sandflats,   mudflats	Same as feeding areas	Insects, molluscs, crustaceans, worms		Sc IV	Migratory
24	Charadrius mongolus	Lesser sand plover	Sandy shores, mudflats, mangroves		Insects, crustaceans, worms		Sc IV	Migratory
25	Charadrius leschenaultii	Greater sand plover	Shores, brackish water, mudflats/sandflats		Molluscs, snails, curstaceans		Sc IV	Migratory
26	Charadrius alexandrinus	Kentish plover	Open flats, nearby fields, saltpans		Polychaetes, crabs and other crustaceans, insects, molluscs		Sc IV	Migratory
27	Vanellus indicus	Red-wattled lapwing	Open areas near water	On ground, amid pebbles	Insects, snails, crustaceans, other invertebrates, grains		Sc IV	Resident
28	Limosa limosa	Black-tailed godwit	Saltmarsh, mudflats		Polychaetes, crustaceans, insect larvae, fish eggs	NT	Sc IV	Migratory
29	Limosa lapponica	Bar-tailed godwit	Intertidal muddy shores, man-groves, tidal mudflats, sandbars		Annelids, bivalves, crustaceans, small fish	NT	Sc IV	Migratory
30	Numenius arquata	Eurasian curlew	Mudflats/sandflats, man-groves, saltmarshes, meadows		Annelids, insects, crustaceans, molluscs	NT	Sc IV	Migratory
31	Numenius phaeopus	Whimbrel	Mudflats/sandflats, mangroves, marshes		Small crabs, other crustaceans, polychaetes		Sc IV	Migratory
32	Philomachus pugnax	Ruff			Crustaceans, molluscs, small fish, insects		Sc IV	Migratory
33	Calidris ferruginea	Curlew sandpiper	Mudflats, clam beds, oyster beds, shallow water		Polychaetes, molluscs, crustaceans, small seeds	NT	Sc IV	Migratory
34	Tringa glareola	Wood sandpiper	Mudflats, marshes, estuarine shores		Crustaceans, molluscs, small fish		Sc IV	Migratory
35	Tringa erythropus	Common greenshank					Sc IV	Migratory
36	Tringa totanus	Common redshank	Saltmarshes, tidal mudflats		Molluscs, crusta-ceans, small fish, insects		Sc IV	Migratory
37	Tringa ochropus	Green sandpiper	Saltmarshes, tidal mudflats		Crustaceans, insects, worms, Neries, annelids		Sc IV	Migratory
38	Actitis hypoleucos	Common sandpiper	Mangroves, marshes		Molluscs, snails, crustaceans, annelids, small fish, plant seeds		Sc IV	Migratory
39	Tringa stagnatilis	Green sandpiper	Swamps, salt-pans, saltmarshes, mudflats		small fish, crustaceans, molluscs, insects		Sc IV	Migratory
40	Arenaria interpres	Ruddy turnstone	Mangroves, swamps, mudflats, saltmarshes		Insects, crustaceans, molluscs, annelids, echinoderms, small fish		Sc IV	Migratory
41	Calidris minuta	Little stint	Mudflats/sandflats, saltpans		Annelids, small molluscs, crustaceans, insects, plant materials		Sc IV	Migratory
42	Calidris alpina	Dunlin	Mudflats, saltpans, flooded areas		Polychaetes, crustaceans, insects, bivalves, gastropods, small fish		Sc IV	Migratory
43	Calidris alba	Sanderling	Rocky, muddy estuarine shores, mudflats, beaches of estuarine mouths		Molluscs, crustaceans, polychaete worms, fish		Sc IV	Migratory
44	Haematopus ostralegus	Eurasian oystercatcher	Saltmarshes, estuarine shores		Polychaetes, molluscs, crustaceans	NT	Sc IV	Migratory
45	Himantopus himantopus	Black-winged stilt	Sand and water	Among reeds and grasses	Insects, molluscs, crustaceans, small fish, seeds		Sc IV	Migratory/resident
46	Recurvirostra avosetta	Pied avocet	Mudflats, saltpans, saltmarshes		Polychaetes, molluscs, small fish, plant matter		Sc IV	Migratory
47	Larus brunnicephalus	Brown-headed gull	Mudflats		Fish, shrimps, also scavenging		Sc IV	Migratory
48	Larus ridibundus	Black-headed gull	Estuary		Fish, shrimps, insects, worms; scavenging		Sc IV	Migratory
49	Larus genei	Slender-billed gull	Estuaries and inshore waters		Fish, crustaceans, insects, other invertebrates		Sc IV	Migratory
50	Gelochelidon nilotica	Gull-billed tern	Marshes, mudflats, saltpans, adjoining wetlands		Insects in all stages, small invertebrates		Sc IV	Migratory
51	Hydroprogne caspia	Caspian tern	Marshes, open water, mudflats, sandy areas		Fish, eggs and young of other birds, aquatic invertebrates		Sc IV	Migratory
52	Sterna aurantia	River tern	Marshes, open water, mudflats, sandy areas		Fish, small crustaceans and insects	NT	Sc IV	Migratory
53	Thalasseus bengalensis	Lesser crested tern	Estuary		Fish, shrimps		Sc IV	Migratory
54	Sterna hirundo	Common tern	Estuaries, shores, saltpans		Small fish, planktonic crustaceans, insects		Sc IV	Migratory
55	Chlidonias hybrida	Whiskered tern	Estuaries, mudflats, mangroves		Crabs, shrimps, fish, insects		Sc IV	Migratory
56	Dendrocygna javanica	Lesser whistling duck	Estuaries	Mangroves	Plant parts, grains, fish, molluscs, worms		Sc IV	Resident
57	Tachybaptus ruficollis	Little grebe	Estuaries, mangroves, marshes		Small fish, crustaceans, molluscs, insects		Sc IV	Migratory
58	Anas poecilorhyncha	Spot-billed duck	Estuaries	Nesting at ground level	Seeds and other plant parts, insects, molluscs		Sc IV	Resident
59	Anas acuta	Northern pintail	Estuaries		Algae, plant parts, fish, molluscs, crustaceans		Sc IV	Migratory
60	Spatula clypeata	Northern shoveller	Estuaries, mudflats, shoreline, marshes		Vegetative parts of plants, fish, crustaceans, insects		Sc IV	Migratory
61	Anas querquedula	Garganey	Estuaries	Sighting only			Sc IV	Migratory
62	Mareca strepera (Anas strepera)	Gadwall			Plant parts, insects, crustaceans, molluscs		Sc IV	Migratory
63	Anas crecca	Common teal	Estuaries, shallow marshes with thick cover		Seeds of aquatic plants, invertebrates		Sc IV	Migratory
64	Elanus caeruleus	Black-shouldered kite	Sandy, rocky parts, salt pans, marshes		Invertebrates, including insects, fish eggs, small fishes		Sc I	Migratory
65	Haliastur indus	Brahminy kite	Various habitats	Large trees	Feeds on fish, dead and alive, crabs, carrion, rodents, small birds, chicks		Sc I	Resident
66	Circus aeruginosus	Eurasian marsh harrier	Reed marshes.		Small mammals, small birds, insects, reptiles		Sc I	Migratory
67	Milvus migrans	Black kite			Rodents, lizards, injured birds, eggs and chicks		Sc I	Resident/locally migratory
68	Haliaeetus leucogaster	Whitebellied sea eagle	Estuarine and marine areas	Large trees	Fishes, eels, crustaceans, turtles, sea snakes, birds, small mammals		Sc I	Resident
69	Spilornis cheela	Crested serpent eagle		Large trees	Lizards, snakes, small birds, fishes, crabs		Sc I	Resident
70	Pandion haliaetus	Osprey	Mangroves	Locations near water	Mainly fishes; occasionally other animals		Sc I	Resident/locally migratory
71	Falco tinnunculus	Common kestrel	Marshlands	Nearby rocky places	Rodents and small birds		Sc I	Resident/locally migratory
72	Halcyon smyrnensis	White-breasted kingfisher	.		Fishes, crustaceans,, snails, etc		Sc IV	Resident
73	Halcyon capensis	Stork-billed kingfisher			Fishes, crabs, rodents, chicks		Sc IV	Resident
74	Halcyon pileata	Black-capped kingfisher	Mangroves		Fishes, large insects		Sc IV	Resident/locally migratory
75	Alcedo meninting	Blue-eared kingfisher	Mangroves;		Fishes, crustaceans, insects, larvae		Sc IV	Resident
76	Ceyx erithacus	Oriental dwarf   kingfisher			Insects, small lizards		Sc IV	Resident/locally migratory
77	Ceryle rudis	Lesser pied kingfisher			Fishes, aquatic insects, molluscs		Sc IV	Resident
78	Pavo cristatus	Indian peafowl	Vagrant in estuarine peripheral fields		Various		Sc I	Resident
79	Corvus splendens	House crow	Generalist	Mangroves	Various animals, carrion			Resident
80	Corvus macrorhyncos	Jungle crow	Generalist, rare in estuary					Resident
90	Dendrocitta vagabunda	Rufous treepie	Occasional in estuarine villages				Sc IV	Resident
91	Centropus sinensis	Indian coucal	Frequent in estuarine villages				Sc IV	Resident
92	Cypsiurus balasiensis	Asian palm-swift			Mostly insects		Sc IV	Resident
93	Apus affinis	Little swift			Insects		Sc IV	Resident
94	Columba livia	Blue rock pigeon			Grains, seeds		Sc IV	Resident
95	Streptopelia chinensis	Spotted dove			Seeds, grains, fruits, insects		Sc IV	Resident
96	Treron phoenicoptera	Yellow-legged green pigeon		Mangroves and bushes	Fruits, berries, grains		Sc IV	Resident
97	Psittaculacyanocephala	Plum-headed parakeet			Grains, fruits, the fleshy petals of flowers		Sc IV	Resident
98	Psittacula krameri	Rose-ringed parakeet					Sc IV	Resident
99	Eudynamys scolopacea	Asian koel	Mangroves		Omnivorous		Sc IV	Resident
100	Tyto alba	Barn owl	Mangroves		Birds, small mammals, rodents, lizards, snakes		Sc IV	Resident
101	Athene brama	Spotted owlet		Hollows of trees;	Rodents, molluscs, small birds, insects		Sc IV	Resident
102	Merops orientalis	Small bee-eater			Insectivorous		Sc IV	Resident
103	Coracias benghalensis	Indian roller			Insects, small reptiles		Sc IV	Resident
104	Dinopium benghalense	Blackrumped wood-pecker			Beetle larvae, termites, nectar		Sc IV	Resident
105	Celeus brachyurus	Rufous wood-pecker					Sc IV	Resident
106	Picus xantho-pygaeus	Streak-throatedwood-pecker					Sc IV	Resident
107	Dendro-copos mahrattensis	Yellow-crowned woodpecker					Sc IV	Resident
108	Hemicircus canente	Heart-spotted woodpecker		Nesting in tree holes;	Insects from tree bark		Sc IV	Resident
109	Galerida cristata	Crested lark	Mangroves, estuary		Grains, seeds, insects		Sc IV	Locally migratory
110	Hirundo daurica	Red-rumped swallow			Insectivorous		Sc IV	Resident
111	Hirundo rustica	Barn swallow			Insectivorous		Sc IV	Resident
112	Lanius cristatus	Brown shrike			Insectivorous		Sc IV	Migratory
113	Dicrurus macrocercus	Black drongo			Insectivorous, seeds		Sc IV	Resident
114	Dicrurus paradiseus	Greater racket-tailed drongo			Insectivorous, seeds		Sc IV	Resident
115	Dicrurus caerulescens	White-bellied drongo			Insectivorous, seeds		Sc IV	Resident
116	Acridotheres tristis	Common myna			Omnnivorous		Sc IV	Resident
117	Pericrocotus flammeus	Scarlet minivet			Insectivorous		Sc IV	Locally migratory
118	Aegithina tiphia	Iora			Insectivoros		Sc IV	Resident
119	Zosterops palpebrosus	Oriental white-eye	Mangroves		Insectivorous		Sc IV	Resident
120	Pycnonotus jocosus	Redwhiskered bulbul			Fruits		Sc IV	Resident
121	Pycnonotus cafer	Red-vented bulbul			Fruits		Sc IV	Resident
122	Turdoides striatus	Jungle babbler			Insects, grains, nectar, berries		Sc IV	Resident
123	Acro-cephalus dumetorum	Blyth’s reed-warbler			Insects, snails, seeds		Sc IV	Migratory
124	Phyllo-scopus trochiloides	Greenish warbler					Sc IV	Resident
125	Orthotomus sutorius	Common tailorbird	Mangroves.		Insects, larvae, tiny fruits and seeds		Sc IV	Resident
126	Copsychus saularis	Magpie robin	for nesting;	Tree hollows	Insects, worms, fishes		Sc IV	Resident
127	Parus major	Great tit	;	Cavity nester	Insects		Sc IV	Resident
128	Motacilla alba	White wagtail			Insects, crustaceans, worms, small fishes		Sc IV	Resident
129	Motacilla maderaspatensis	Large pied wagtail			Insects, caterpillars		Sc IV	Resident
130	Anthus rufulus	Paddyfield pipit	Fields and and open dry areas;		Insects, snails		Sc IV	Resident
131	Dicaeum erythrorhynchos	Tickell’s flowerpecker			Berries		Sc IV	Resident
132	Nectarinia asiatica	Purple sunbird			Visits Acanthus ilicifolius for nectar		Sc IV	Resident
133	Nectarinia zeylonica	Purple-rumped sunbird			Visits Acanthus ilicifolius for nectar		Sc IV	Resident
134	Passer domesticus	House sparrow	Open, dry spots		Grains, seeds, insects		Sc IV	Resident
135	Lonchuramalacca	Blackheaded munia	Amidst sedges and grasses in marshes				Sc IV	Resident
136	Ploceus philippinus	Baya weaver		Nesting on trees, rare			Sc IV
137	Terpsiphone paradisi	Asian paradise flycatcher	In dense mangroves		Feeds on insects in air;		Sc IV	Migratory
138	Pitta brachyura	Indian pitta		Nesting on low trees	Insects and small gastropods		Sc IV	Resident

ESTUARINE BIRDS

A general discussion on estuarine birds, especially of the Indian west coast, is included as the estuarine ecosystems are similar in their underlying processes. Borges and Shanbhag (2007) identified in the Mandovi estuarine wetlands (including the Salim Ali Bird Sanctuary of Chorao Island) of Goa 151 species of birds. Borges and Shanbhag’s (2008) work on the food resource partitioning among waterbirds wintering in the Diwar wetland in Mandovi brings to light the immense importance of the wetlands in the feeding of water birds, especially waders. The wetland had 52 species of waterbird, most of them migrants. The waders, notably plovers, stints, redshanks, culews and whimbrels, used sandflats as feeding grounds. The increase in waterbird densities, especially in winter, paralleled the densities of benthic invertebrates. Waders were significantly dependent on polychaetes. Larger waders also consumed hermit crabs. Large flocks of pintail ducks foraged on the Nereis inhabiting silty sand underneath macrophytic mats, while gulls fed on the Cerethidia flava inhabiting the sandflats. These feeding patterns showed how the food resources of the wetland were partitioned, thereby minimizing competition between consumer birds.

In Kerala Mohandas et al. (1994) reported 57 species of bird occurring in the Asramam mangroves at Kollam, and Jayson (2002) recorded 182 taxa of birds from the Kole wetlands of Thrissur in Kerala. The Kadalundi–Vallikunnu Community Reserve in Kerala, the first of the five community reserves in India and the smallest, having an area of 1.5 km², had 110 species of bird (Kanagavel et al. 2013). The Kuttanad wetland system, towards the southern portion of the Vembanad-Kole Ramsar site with an estimated extent of 53,639 ha, in southern Kerala, having fresh water in the upper Kuttanad and growing increasingly saline down the estuarine system, was rich in bird diversity (225 species). Of these birds, 38 per cent were migrants, 38 per cent residents, 16 per cent local migrants and the rest belonging to miscellaneous groups (Narayanan et al. 2011). The Mangalavanam Wildlife Sanctuary, Kochi, a mangrove sanctuary covering just 2.74 ha, had 49 species of bird according to a study conducted in 1998–1999 (Jayson 2001). Spread across 3 km², the Kadalundi–Vallikunnu estuary, located in Kozhikode (Calicut) and Malappuram districts of Kerala, is the first community reserve of India. It was declared in 2007. The reserve is managed by a committee jointly set up by the Kadalundi and Vallikunnu panchayats. The reserve had 109 species of bird, 65 of them (60 per cent) migratory, including all the five species of gull found in Kerala (Aarif et al. 2015).

 

Migrant birds: Three migratory flyways for birds cross Asia: these are the West Pacific Flyway, East-Asian Australasian Flyway, and the Central Asian Flyway. The CAF comprises several important migration routes of water birds, most of which extend from the northernmost breeding grounds in Siberia and covers 30 countries of North, Central and South Asia and Trans-Caucasus. India is the core country of the CAF and supports 257 species of water birds. Of these, 81 species are migratory birds of CAF conservation concern, including three critically endangered species, six endangered species and 13 near threatened species. The Western Flyway of CAF covers Rann of Kutch and progresses southwards along the Western Ghats-west coast of India (Bird Life International, Data zone, 2009). The Indian west coast is rich in the estuaries of numerous small and medium rivers playing vital role in the lives of migratory birds along the Western Flyway of CAF.

Of the 56 species of birds associated with the mangroves of the Uran estuary in the Raigad coast of Maharashtra, Pawar (2011) noted 20 (36 per cent) were winter migrants. Of the 9 IUCN threatened species found in Aghanashini estuary, only Limosa limosa (Black-tailed Godwit) was found in Uran estuary. Aarif et al. (2015) recorded 65 migratory bird species in the 3 km² area Kadalundi-Vallikunnu Community Reserve of. Chandrakasan and Jayson (2001) noted that of the 167 species of birds recorded from the Kole wetlands of Thrissur district in Kerala 53 species (32 per cent) were winter visitors.

On estuarine habitats and food diversity: The waders, or shorebirds, constitute a very important group of estuarine birds with long legs which frequent shallow water and intertidal mudflats, where they search for food. Herons, egrets, ibises, bitterns, spoonbills and storks are among the waders. Rails are small-sized waders with very long toes that enable them to run on soft mud. Various quail-like birds, characterized by the missing hind toe, are waders inhabiting grassy plains. Waders are important groups of mangrove and mudflat birds (Oswin 1999; Chaudhary-Pachpande and Pejavar 2016). The probing shorebirds are associated with intertidal and shallow water habitats. Plovers, snipes, curlews, whimbrel, sandpipers, godwit, turnstone, stilts, waterfowls, lapwings, moorhens, etc. feed on fishes and invertebrates (Oswin 1999). Gulls and terns are expert divers and mainly forage by diving with force where fishes are available. Gulls also feed on discarded and dead fishes in fishing areas.

Terminal consumers of detritus food chains: Several species of bird are dependent on the detritivorous benthic organisms of the estuary. Whereas in the open ocean the source of detritus is only plankton, in coastal waters and estuaries, in addition to planktonic material, benthic plants and animals and other types of material brought down by the rivers, outfalls and run-off form a rich source of detritus (Darnell 1967). Suspended detritus consists of particles of fine silt and sand, around which organic matter and bacteria adhere and form aggregates of different shapes and sizes. Settled detritus is a heterogenous mixture of animal and plant remains, silt and sand particles coated with decaying (organic) matter and large colonies of bacteria and infusorians. Often the importance of settled detritus as food of adult fishes is much greater than that of all the other food groups combined. Since estuaries are shallow, a large fallout of plant and animal materials as organic detritus takes place (Sathiyamurthy and Purushothaman 1992).

The mangroves, marshes, mudflats and gazni rice fields are extremely rich in organic detritus, on which many invertebrates depend. The gastropods feed on fallen leaves of mangroves and may consume mud (mainly formed by mangrove litter and other organic detritus from upstream areas of the Western Ghats, brought down by the river). Molluscan bivalves feed on suspended organic food particles by filtering them. Oysters and mussels also carry out similar filter feeding in detritus-rich areas. Birds which feed on molluscs (bivalves, gastropods, etc.), prawns and crabs, polychaetes, amphipods, nematodes, etc. are therefore almost terminal consumers in short, detritus-based food chains operating in the estuary. In the Mandovi estuary of Goa, Borges and Shanbhag (2008) found that the waterbird (ducks, gulls and wading birds) population increased concomitantly with the collective population of the benthic invertebrates. Whereas the ducks foraged for these detritivores under algal mats, the storks were found feeding on gastropods and other invertebrates on exposed sandflats or on shallow bivalve beds. The gulls were observed feeding on hermit crabs on sandflats, after breaking the shells of the gastropods covering the bodies of crabs on exposed rocks. The waders had a significant dependence on the polychaetes in the mudflats. They fed mostly on nereids (Nereis, etc.) from the top 5 cm of the mudflats. The larger waders fed on hermit crabs from exposed sandflats. All the waterbirds and waders (their numbers are highest in winter) feed on estuarine benthic invertebrates. The wetlands were important stopovers for the waders migrating along the Central Asian Migratory Flyway (Bird Life International, Data Zone, 2009). The investigators found the densities of crustaceans and other soft-bodied invertebrates to be highest during the post-monsoon period, declining sharply in winter.

The detritus feeders graze upon the floor, swallowing larger aggregates of detritus with mud or scraping adhered material from submerged objects such as rocks, shells, pilings and wooden or metal structures. The detritus food chain through the fishes to the birds is very important in estuaries. Many species of fish combine detritus with the other food materials. Liza parsia stomach content contained plant food and detritus. Mugil cephalus and Gerres filamentosus had plant and animal material and detritus (Jeyaseelan and Krishnamurthy 1980). As a large number of fish species feed on benthic detritus-feeding organisms, the birds eating such fishes are the ultimate beneficiaries of the detritus food chains operating in the estuaries. The fish species found in Aghanashini which are known to have varied degrees of dependence on organisms feeding on detritus (e.g. crustaceans, molluscs, polychaete worms and other invertebrates) include Arius arius, Crossorhombus azureus, Cyanoglossus macrostomus, Nemepterus japonicus, Pseudorhombus javanicus, Scatophagus argus, Otolithes ruber, Sillago sihama and Terapon jarbua (details of detritus dependence from http://www.fishbase.org/summary/785).

In fact the large congregations of birds in the Aghanashini estuary can be explained by their dependence on organisms which in turn are directly feeding on detritus or other detritus-feeding organisms lower in the estuarine food web. The presence seasonally or year-round of darters, herons, egrets, storks, spoonbills, waterhens, jacanas, swamp hens, plovers, lapwings, godwits, sandpipers, shanks, turnstones, stints, sanderlings, stilts, avocets, gulls, terns, ducks, etc, highlights the rich presence of detritus-feeding organisms on which these birds depend directly and indirectly through more links.

Shrimp aquaculture impacts on mangroves, detritus and bird fauna: Mangroves are an integral part of tropical estuaries and play a prime role in sustaining the rich bird communities of estuaries. The enormous amount of organic matter associated with mangrove forests contributes substantially to the detritus-based food web which is most important in sustaining fisheries as well as bird diversity. Hong and Tri (1986) estimated the annual output of leaves (dry weight) from a Rhizophora apiculata forest to be 8000–12,000 kg/ha. During decomposition, the mangrove litter becomes progressively enriched in protein and serves as a food source for a wide variety of filter, particulate and deposit feeders such as molluscs, crabs and polychaete worms. These primary consumers in turn form the food of a secondary consumer population (Hamilton and Snedaker 1984).

 

Threatened species: The estuary is noted for the rare presence of some IUCN Red Listed birds.

Anhinga melanogaster Pennant (Oriental darter): Threat category: Near Threatened

A rapid decline of the population globally was noticed. It occurs in South and Southeast Asia. It may be resident to local migrant in Aghanashini estuary. It inhabits shallow portions of wetlands. Habitat loss (both degradation of foraging areas and felling of trees used for breeding), disturbance (at feeding grounds and colonies), hunting, egg collection and pollution were reported as threats (http://www.iucnredlist.org/details/22696712/0).

 

Leptoptilos javanicus Horsfield (lesser adjutant): Threat category: Vulnerable

It is a very large stork, dark grey-black above, white below, with naked head and neck. Its distribution is in South and Southeast Asia. The population is suspected to be rapidly declining due to a variety of threats such as hunting pressure, loss of nesting habitat, cutting down of nesting trees, conversion and degradation of wetlands and agricultural changes and intensification. In estuaries the species is associated with mangroves and intertidal flats as well as adjacent wetlands (http://www.iucnredlist.org/details/22697713/0).

 

Threskiornis melanocephalus Latham (black-headed ibis): Threat category: Near Threatened

A large bird of east, South and Southeast Asia. The population is suspected to be in a moderately rapid decline owing to hunting, egg collection, disturbance at breeding colonies, drainage and agricultural conversion (http://www.iucnredlist.org/details/22697516/0).

Limosa limosa Linnaeus (black-tailed godwit): Threat category: Near Threatened

Large, rather graceful wader, with long bill on a relatively small head, long neck and long legs. Colour of fore-body is dull pink-chestnut in summer, paler grey-brown in winter. In flight has a striking white wing-bar and rump. It is native to the sub-Arctic north. Its migration southwards is to escape the northern winter. Over the past 25 years, up to 2015, the population is estimated to have declined by 23 per cent. Along the coast it winters in estuaries, lagoons, mudflats, saltmarshes, sandy beaches, etc. Pollution, human disturbance, habitat reclamation for tidal energy plants, aquaculture ponds, land conversion for agriculture, urban expansion and agricultural intensification are considered notable threats (http://www.iucnredlist.org/details/22693150/0).

 

Limosa lapponica Linnaeus (bar-tailed godwit): Threat category: Near Threatened

A winter migrant to the south. Medium-sized godwit with slightly upcurved bill and barred tail, in flight lacks white wing bar and has white underwing. Non-breeding adults have pale grey-brown upperparts, partly edged whitish. Breast turns grey with fine dark streaking. Underparts white. Wintering birds come to India. Loss of tidal flats and various developmental activities affecting bird habitats are among the reasons for the decline of the population (http://www.iucnredlist.org/details/22693158/0).

 

Numenius arquata Linnaeus (Eurasian curlew): Threat category: Near Threatened

A winter migrant to the south. Breeding populations in Europe, Russia and Siberian region. Large wader with long down-curved bill. Mottled or streaked brown plumage with whiter belly and undertail. In flight shows pointed whitish rump and barred tail as well as mottled whitish underwings. The wintering birds along the southern coasts are associated with muddy coasts, bays, tidal mudflats and sandflats, rocky and sandy beaches with many pools, mangroves, saltmarshes, coastal meadows, etc. Habitat loss in breeding areas, agricultural intensification, drainage, increased use of inorganic fertilizers and high predation rates on eggs and chicks as well as hunting pressures are among the major threats listed (http://www.iucnredlist.org/details/22693190/0).

 

Calidris ferruginea Pontoppidan (curlew sandpiper): Threat category: Near Threatened

Medium-sized sandpiper. Longish neck and legs and long, decurved bill. Head, neck and all upperparts rusty rufous to deep chestnut-red, with dark streaks on crown. Mantle and scapulars dark brown with chestnut and whitish fringes. Female has longer bill, paler and more likely to have white barring on underparts. Non-breeding adult plain grey above, white below, white supercilium and sides of breast washed grey. Breeding ground is Arctic Siberia. In winter, along the coast, the species chiefly occurs in brackish lagoons, tidal mudflats and sandflats, estuaries, saltmarshes and sandy beaches and saltpans. Loss and degradation of stopover habitats, rising pollution and unsustainable harvests of benthic fauna are listed as reasons. In south India, Illegal hunting, diminishing rainfall and various other anthropogenic factors are cited as threats for migrants (http://www.iucnredlist.org/details/22693431/0).

 

Haematopus ostralegus Linnaeus (Eurasian oystercatcher): Threat category: Near Threatened

The main breeding populations are in northern European countries and the north-west of Russia. Along the Indian coast the wintering populations settle in estuarine mudflats, saltmarshes and sandy and rocky shores. Over-fishing of benthic shellfish and the resulting disappearance of intertidal mussel and cockle beds are considered the major threats. Habitat degradation and disturbances by humans are among other reasons for the decline of this species (http://www.iucnredlist.org/details/22733462/0).

 

Sterna aurantia Gray (Indian river tern) Threat category: Near Threatened

The species occurs mainly in South and Southeast Asia. Increasing human disturbance and dam construction projects are expected to drive a moderately rapid population decline over the next three generations. Unlike in Southeast Asia, where the population decline is severe, the species is reported to be more regular in southern India than was once thought, having probably benefitted from the development of reservoirs (http://www.iucnredlist.org/details/22694537/0).

 

The Indian Wildlife (Protection) Act, 1972 has included some of the estuarine birds under Schedule I, providing absolute protection. The penalties for offences are highest under this schedule. Most other birds are under Schedule IV, which is less stringent. The Schedule I birds recorded from Aghanashini estuary with the help of the ornithology expert Roshmon Thomas were Platalea leucorodia (Eurasian spoonbill), Elanus caeruleus (black-shouldered Kite), Haliastur indus (brahminy kite), Circus aeruginosis (Eurasian marsh harrier), Milvus migrans (black kite), Haliaeetus leucogaster (white-bellied sea eagle), Spilornis cheela (crested serpent eagle), Pandion haliaetus (osprey), Falco tinnunculus (common kestrel) and Pavo cristatus (Indian peafowl). Most of these are predominantly land birds which seek prey in the estuarine environment. The notable exception is the white-bellied sea eagle which is more based in littoral ecosystems.

 

Threats faced by estuarine bird community

Rise of shrimp farms and birds turned into pests: In the traditional rice-cum-fishery farms (e.g. gazni fields of Aghanashini and Pokkali fields of south Kerala), birds were never considered pests but were viewed more as an integral part of estuarine life. The promotion of shrimp monoculture in specially prepared ponds, by converting traditional biodiversity-rich rice-cum-fishery fields, the intense stocking of shrimps and easy availability of prey to the birds attracted more predator birds hovering around these farms to snatch the abundant and easily available prey. This made a major shift in the worldview of the shrimp farmers towards the bulk of the estuarine bird community, given to carnivory. In the shrimp farms of Kannur, Roshnath et al. (2014) noted major threats from cormorants, while other problematic species were the night herons, little grebe, egrets, kingfishers, storks, darter, green herons and whistling ducks. Upsets in the bird population patterns favouring more predator species may be considered an adverse impact of shrimp monoculture on natural estuarine ecosystems which have a high diversity of birds and abundance of food.

 

PROBLEMS AND PROSPECTS

Estuaries are the expressions of rivers meeting the sea. The mixing of fresh water from the land and the oceanic salt water in a coastal basin produces a unique set-up of brackish water and circulation patterns in tune with the differential mixing of the very fluctuating flow from the river with the nearly uniform and powerful oceanic tides, setting up circulation and depositional patterns that are distinctive of estuaries. In tune with the geomorphology, vegetation and hydrological patterns of the river catchment, the estuaries tend to develop their individual features. Compared with inland waters or ocean water, the primary productivity of an estuary is rated high. Cooper (2002–2017) places typical estuarine production in the range of 10–25 g of dry organic matter per square metre per day compared with 1 g in the open sea and 0.5–3 g in coastal waters. Many marine and freshwater organisms consequently spend the juvenile phase of their development in estuaries, where a good food supply and low abundance of predators favour survival.

Through the ages, estuaries have been favoured places for human settlements, leading in due course the rise of major coastal cities, flourishing ports and trade centres, also places prioritized for setting up industrial hubs. The ever-increasing human interventions progressing in uncharted dimensions have brought the state of numerous estuaries to a near-disastrous state. The Indian west coast estuaries, along with the Western Ghats, a global biodiversity hotspot, constitute a major part of the Western Flyway of the Central Asian Flyway (CAF), an important pathway for north–south migration of birds. The waterbirds especially look forward to spending days, weeks or months as part of the flourishing estuarine ecosystems, feeding on the high diversity and abundance of protein-rich faunal components, ranging from the polychaetes and shellfish to fish and reptiles.

The traditional estuarine uses by humans of pre-industrial times had no notable impacts on their structural and functional integrity and capacity to sustain large flocks of birds. As far as Aghanashini estuary is concerned, such integrity and naturalness continued till the 1970s, hosting congregations of birds seeking food in its richly productive water, mangrove swamps, mudflats and oyster beds, gazni rice fields and rocky and sandy shores towards the river mouth. No hydroelectric projects existed upstream, and this is true to this day, unlike in the neighboring Sharavathi, wherein a near collapse of the ecosystem happened, wiping out bivalves and altering the fishery drastically as reduced salinity due to incessant fresh water input from upstream dams crippled its capacity to serve as nurseries for marine fishes and crustaceans (as discussed in the earlier chapters).

From the late 1970s the state’s promotion of export-oriented shrimp production farms caused conversion of substantial portions of the erstwhile detritus-rich gazni rice fields, in a mosaic with reed-swamp islands within them, into aquaculture farms. Aquafarms, in general, all over the country, released untreated effluents, toxic pollutants and pathogens into the estuarine environment, which are expected to have a serious impact on the juveniles of fishes, shellfish and crustaceans. No studies were made on the impacts of these interventions on the extensive and richly productive mudflat ecosystems, the most favoured feeding places for especially the waterbirds, both residents and migrants. The period from the 1970s to the 1990s was a critical one for the bird fauna, mainly due to wanton destruction of mangroves, which are at the core of estuarine ecology and critical roosting, nesting and feeding areas for migrant and resident birds.

The marine fishing along Karnataka’s coast witnessed phenomenal growth from the early 1970s till today with unregulated introduction of mechanized crafts and modern gear for effective fishing, aimed more at commercial production and exports. In tune with global trends in capture fisheries, Karnataka’s fishery also witnessed a serious downfall, which in a way intensified fishing efforts in the estuaries, unmindful of the fact that the estuaries are important nurseries for various kinds of marine fishes and crustaceans. The fishing gear being used in Aghanashini, for example, although of the traditional kind, have no mesh restriction and are effective in trapping juveniles of fish and prawns on a massive scale.

The estuary has been subjected to severe exploitation of molluscan shells for industrial purposes. The shell mining was carried out with utter disregard towards the ecological impacts on mudflats and clam and oyster beds. The edible bivalve resources also were subjected to unprecedented levels of extraction, aiming at meeting growing demands from urban centres, especially the demand from Goa, where the bivalve production had collapsed in recent years (discussed previously in the report on molluscan bivalves). Aghanashini, which was subjected to severe over-exploitation in terms of clams and oysters—an annual production over 22,000 tons reported by Boominathan et al. (2008) produced from its clam and oyster beds—saw a serious collapse in shell production, to almost nil during 2015–2016. As discussed previously (also see Table 5.1), it is easy to visualize how the shellfish production would have adversely affected the wader bird population. Notably, although we have no estimates, the trophic base of the herons, egrets, spoonbills, waterhens, jacanas, plovers, curlews, sandpipers, turnstones, stints, sanderlings, oystercatchers, stilts, avocets, ducks, grebes, etc. would have been affected by the depletion of estuarine bivalves.

A basic understanding of the dependence of globally threatened bird species on estuarine/coastal ecosystems could be a strong reminder for us to raise the standards of coastal ecosystem management. The IUCN Red list of Threatened Species, in its species-appraisal, has categorically referred to overfishing, bivalve depletion, sand and shell mining, juvenile destruction, conversion of marshy, swampy areas (mainly for aquaculture), destruction of nesting/roosting sites, pollution and even decline of traditional agriculture as among the threats faced by many birds (all these threats also applicable to the Aghanashini estuary). The Near Threatened Sterna aurantia, Haematopus ostralegus, Caladris ferruginea, Numenius arquata, Limosa lapponcia, L. limosa and Threskiornis melanocephalus as well as the Vulnerable category Leptoptilos javanicus are affected by such threats operating in the Aghanashini estuary as well.

Recommendations for conservation, incorporating also some details from Birdlife International, Datazone (2009)  are given below:

• There is data deficiency on precise and up to date information on water bird populations, which necessitates population counts of especially dwindling water birds species.
• Identify the nesting areas of sensitive species. The forest department, jointly with the local Biodiversity Management Committees, and associations of stakeholders and NGOs, should initiate community-based protection of all important bird nesting areas.
• As estuarine areas are densely populated awareness programmes for all concerned and  stakeholders’ participation are essential.
• Support should be given to traditional Kagga rice cultivation in estuarine rice fields as such rice fields are reservoirs of organic nutrients from the good quantity of rice straw left behind in the fields.
• Management of shellfish habitat and implementation of sustainable harvest standards are critical.
• While shell mining has to be stopped in the estuary, sand mining is to be allowed strictly within sustainable yield limits to be fixed.
• As there is hardly anyone devoted to bird studies, monitoring of critical bird populations of species which are reflective of estuarine health, a team of local volunteers has to be trained as parataxonomists, especially to undertake year-round observations and prepare records for groups of birds. They can also be trained as tourist guides having scientific knowledge of mangroves, birds and other key estuarine habitats and organisms.
• Mesh size restrictions on fishing and crustacean nets are critical for restoring healthy fisheries not only in the estuary but also in the sea and to restore healthy levels of bird populations.
• Shrimp farms and their methods of culturing have to be brought under the scanner so that they adhere to the appropriate legislations in the country governing these areas. Use of chemicals in shrimp farms has to be strictly monitored and the shrimp farmers may declare in writing the culture (of shrimps, fish, crabs) practices adopted so that timely advisories may be released by the conservation agencies concerned. 
• A watch should kept on poaching of eggs of birds and on hunting and trapping them, through local community participation, Biodiversity Management Committees and trained parataxonomy volunteers.
• Water and soil testing for pollution should be ongoing programmes, and sources of contamination should be identified for the government to adopt appropriate steps.
• Organic farming should be promoted in the estuarine and upstream area villages.
• The Karnataka Biodiversity Board had already recommended Biodiversity Heritage Site status for Aghanashini estuary under the provisions of the Biodiversity Act, 2002 of the Government of India. But due to a lack of administrative support, the recommendation remains dormant. It has to be taken up again by the KBB and put up before the government for implementation.

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Annexure – 1 (Birds encountered during sampling – month wise during the three consecutive years)

S L No	Scientfic Name	Birds Name	Birds  count	Total during a year
1	Plegadis falcinellus	Glossy Ibis	40-45	350
2	Phalacrocorax carbo	Large Cormorant	80-85	280
3	Anhigna rufa	Darter	20-25	60
4	Phalacrocorax niger	Little Cormorant	250-260	600
5	Egretta garzetta	Egrets	920-925	3490
6	Ardeola striatus	Little Green Heron	115-120	780
7	Ardeola grayii	Pond Heron	220-230	940
8	Egretta gularis	Indian Reef Heron	70-80	452
9	Ciconia episcopus	Whitenecked Stork	40-45	320
10	Threskiornis aethiopica	White Ibis	250-260	650
11	Amaurornis phoenicurus	Whitebreasted Waterhen	60-70	230
12	Anastomus oscitanus	Openbill Stork	80-85	652
13	Nycticorax nycticorax	Night Heron	270-280	800
14	Ardea insignis	Great Whitebellied Heron	40-45	120
15	Ardea purpurea	Purple Heron	60-65	189
16	Ardea cinerea	Grey Heron	140-145	890
17	Dendrocygna javanica	Lesser Whistling Teal	310-320	912
18	Anas acuta	Pintail	180-190	920
19	Anas crecca	Common Teal	120-130	810
20	Haliastur indus	Brahminy Kite	140-145	912
21	Milvus migrans	Common Pariah kite	140-150	765
22	Accipiter badius	Shikra	60-65	240
23	Haliaeetus leucogaster	Whitebilled Sea Eagle	80-90	500
24	Porphyrio porphyrio	Purple Moor Nen	245-250	1200
25	Fulica atra	Coot	200-215	890
26	Amaurornis akool	Brown Crake	60-70	120
27	Himantopus himantopus	Blackwinged Stilt	220-230	870
28	Vanellus indicus	Red-Wattled Lapwing	130-140	560
29	Vanellus malabarucus	Yellow -Wattled Lapwing	60-65	180
30	Numenius arquata	Curlew	130-135	421
31	Numenius phaeopus	Whimbrel	80-85	300
32	Tringa totanus	Redshank	140-145	620
33	tringa stagnatilis	Marsh Sand piper	120-130	560
34	Tringa nebularia	Greenshank	85-90	320
35	Tringa hypoleucos	Common Sandpiper	150-160	678
36	Charadrius dubius	Little Ringed Plover	80-90	189
37	Calidris testacea	Curlew Sandpiper	60-65	120
38	Larus fuscus	Lesser Blackbacked Gull	145-150	992
39	Larus brunnicephalus	Brown Headed Gull	230-335	1923
40	Larus ridibundus	Blackheaded Gull	150-155	1002
41	Gelochelidon nilotica	Gullbill Tern	180-185	1239
42	Hydroprogne caspia	Caspian Tern	160-165	1670
43	Sterna hirundo	Common Tern	220-225	1780
44	Sterna aurantia	River Tern	250-250	1820
45	Chalcophaps indica	Emerald Dove	60-65	178
46	Psittacula krameri	Rose Ringed Parakeet	145-150	340
47	Cuculus canorus	Cuckoo	90-95	289
48	Tyto alba	Barn Owl	30-35	120
49	Ceryle rudis	Pied Kingfisher	70-75	210
50	Pelargopsis capensis	Storkbilled Kingfisher	90-95	320
51	Meropus orientalis	Small Green Bee-Eater	140-145	700
52	Coracias Benghalensis	Indian Roller	75-80	210
53	Upupa epopus	Hoopoe	40-45	127
54	Tockus birostris	Common Grey Hornbill	140-145	520
55	Anthracoceros malabaricus	Indian Pied Hornbill	80-90	240
56	Dryocopus javensis	Great Black Woodpecker	70-75	210
57	Pitta brachyura	Indian Pitta	40-45	120
58	Hirundo smithii	Wiretailed Swallow	80-85	256
59	Oriolus oriolus	Golden Oriole	75-80	278
60	Oriolus xanthornus	Blackheaded Oriole	120-125	789
61	Dicrurus adsimilis	Black Drongo	150-160	600
62	Dicrurus paradiseus	Racket Tailed Drongo	70-80	320
63	Dendrocitta vegabunda	Tree Pie	130-135	390
64	Aegithina tiphia	Iora	135-140	421
65	Pycnonotus cafer	Redvented Bulbul	150-160	452
66	Terpsiphone paradisi	Paradise Flycatcher	80-85	230
67	Orthotomus sutorius	Tailor bird	130-135	410
68	Treron phoenicoptera	Common Green Pigeon	180-185	578
69	Columba livia	Blue Rock Pigeon	220-225	720
70	Contropus toulou	Lesser Coucal	200-210	614
71	Caprimulgus asiatcus	Common Indian Nightjar	40-45	120
72	Apus affinis	House Swift	80-85	245
73	Megalaima viridis	Smlaa Green Barbet	120-125	360
74	Mirafra assamica	Bush Lark	230-240	782
75	Oriolus chinensis	Blacknaped Oriole	130-140	390
76	Gracula religiosa	Hill Myna	40-45	92
77	Pericrocotus  ethologus	Scarlet Minivet	70-80	178
78	Turdoides affinis	Whiteheaded Babbler	130-140	189
79	Turdoidesstriatus	Jungle Babbler	180-185	378
80	Nectarinia zeylonica	Purplerumped Sunbird	190-195	666

Annexure II: Habitat wise birds distribution

Scientyfic Name	Family	Birds Name	Forest	Eastury	Marsh /Gajani	Paddy	Mangrove	Laterite	Wetland	Migratory
Phalacrocorax carbo	Phalacrocoracidae	Large Cormorent		p	p		p		p
Phalacrocorax niger	Phalacrocoracidae	Little Cormorent		p	p		p		p
Anhinga rufa	Anhingidae	Darter			p				p
Ardea insignis	Ardeidae	Great whitebilled Heron			p		p		p
Ardea alba	Ardeidae	Large Egret			p	P	p	p	p	R M
Ardea purpurea	Ardeidae	Purple Heron		p	p	P	p	p	p	R M
Ardea cinerea	Ardeidae	Grey Heron			p		p		p
Adreola striatus	Ardeidae	Little green Heron			p		p		p
Nycticorax nycticorax	Ardeidae	Night Heron					p		p
Adreola grayii	Ardeidae	Pond Heron		p	p	p	p	p	p
Bubulcus ibis	Ardeidae	Cattle Egret		p	p	P	p	p	p
Egretta Intermidia	Ardeidae	Smaller Egret		p	p	p	p	p	p
Egretta gularis	Ardeidae	Indian reff Heron		p	p		p		p
Egretta garzetta	Ardeidae	Little Egret	p	p	p	p	p	p	p
Anastomus oscitans	Ciconiidae	Openbill Stork		p	p	p	p		p
Ciconia episcopus	Ciconiidae	Whitenecked stork		p	p		p		p
Ciconia nigra	Ciconiidae	Black stork		p	p		p		p
Leptoptilos javanica	Ciconiidae	Lesser Adjutant	p		p				p	R M
Threskiornis aethiopica	Threskiornithidae	White Ibis		p	p	p	p		p
Dendrocygna javanica	Anatidae	Lesser whistiling duck		p					p	R uncommon
Anas clypeata	Anatidae	Northern shoveller			p				p
Anas poecilorpyncha	Anatidae	Spot-billed duck			p				p
Gallinula chliropus	Rallidae	Common moorhen			p				p
Fulica atra	Rallidae	Common Coot			p				p
Porphyrio porphyrio	Rallidae	Purple moorhen							p
Amaurornis phoenicurus	Rallidae	White breasted waterhen		p	p	p	p		p
Anas acuta	Anatidae	Pintail			p				p	W V
Anas crecca	Anatidae	Common Teal							p	W V
Nettapus coromandelianus	Anatidae	Cotton Teal							p
Haliastur indus	Accipitridae	Brahaminy Kite	p	p	p	p	p	p	p
Circus aeruginosus	Accipitridae	Western marsh Harrier		p					p
Accipiter badius	Accipitridae	Shikra		p	p	p	p		p
Milvus migranus	Accipitridae	Black Kite	p	p	p	p	p	p	p
Spilornis cheela	Accipitridae	Creasted serpent Eagle	p	p			p		p
Esacus recurvirostris	Burhinidae	Great stone Plover	p	p	p				p
Himantopus himantopus	Recurvirostridae	Black-winged stilt			p
Haliaeetus leucoguster	Accipitridae	Whitebelled sea Eagle	p	p	p	p	p	p	p
Valennus indicus	Charadridae	Red-wattled Lopwing	p		p	p		p	p
Valennus malabaricus	Charadridae	Yellow-wattled Lopwing	p			p		p	p
Actitis hapoleucos	Scolopacidae	Common Sandpiper		p	p		p		p
Tringa stagatilis	Scolopacidae	Marsh Sandpiper		p	p		p		p
charadrius dubius	Charadridae	Little ringed Plover		p	p				p
Sterna aurantia	Laridae	River Tern		p					p
Numenius arquata	Scolopacidae	Curlew		p	p				p	W V
Numenius phaeopus	Scolopacidae	Whimbrel		p	p				p	W V
Limosa limosa	Charadridae	Blacktailed Godwint		p	p				p	W V
Limosa lapponica	Charadridae	Bartailed Godwint		p	p		p		p	W V
Tringa totanus	Scolopacidae	Redshank		p	p		p		p
Tringa nebularia	Scolopacidae	Greenshank		p	p		p		p	W V
Tringa hypoleucos	Scolopacidae	Common Sandpiper		p	p		p		p
Charadrius alexandrinus	Charadridae	Kentish Plover		p	p				p
Calidris minuta	Scolopacidae	Little stint		p	p				p
Charadrius mongolus	Charadridae	Lesser Sandplover		p	p				p
Chlidonias hybrida	Laridae	Indian whiskered Tern		p						R M
Gelochelidon nilotica	Laridae	Gulbilled Tern		p
Hydroprogen caspia	Laridae	Caspian Tern		p						Migratory
Sterna hirundo	Laridae	Common Tern		p						R M
Larus fuscus	Laridae	Lesser blackbacked Gull		p						Migratory
Ceryle rudis	Alcedinidae	Pied Kingfisher		p	p	p	p	p	p
Alcedo atthis	Alcedinidae	Smallblue Kingfisher	p	p	p	p	p	p	p
Pelargopsis capensis	Accipitridae	Storkbilled Kingfisher		p	p	p	p		p
halcyon smynensis	Alcedinidae	White breasted kingfisher	p	p	p	p	p	p	p
Merops superciliosus	Meropidae	Bluecheeked Bee -Eater	p	p	p	p	p	p	p
Meropsorientalis	Meropidae	Small green Bee-Eater	p	p	p	p	p	p	p
Nyctyornis athertoni	Meropidae	Bluebearded Bee-Eater	p	p	p	p	p	p	p
Coracias bengalensis	Coracildae	Roller	p		p	p	p	p	p
Upupa epops	Upupidae	Hoopoe	p			p		p
Pavo crstatus	Phasianidae	Indian Peafowl	p			p		p
Streptopelia senegalensis	Colombidae	Pied Kingfisher			p	p		p
Streptopelia chinensis	Colombidae	Spotted Dove	p		p	p	p	p	p
Columba livia	Colombidae	Bluerock Pigeon
psittacula cyanocephala	Psittacidae	Purple headed Parakeet	p			p		p
psittacula krameri	Psittacidae	Roseringed Parakeet	p			p		p
Eudynamys scolopacea	Cuculidae	Asian koel	p					p
Centropus bengalensis	Cuculidae	Lesser coucal	p			p		p
Loriculus vernalis	Psittacidae	Indian hanging Parrot	p			p		p
Clamator jacobinus	Cuculidae	Pied creasted Cuckoo	p					p
Phaenicophaeus viridirostris	Cuculidae	Small greenbilled Malkoha	p					p
Anthracoceros malabarica	Becurotidae	Indian pied Hornbill	p							R M
Anthracoceros coronatus	Becurotidae	Malabar Pied Hornbill	p							R M
Tockus birostris	Becurotidae	Common grey Hornbill	p
Megalaima viridis	Capitonidae	White cheeked Barbet	p
Chrycicilaptes nanus	picidae	White naped Woodpecker	p
Dryocopus javensis	picidae	Great black Woodpecker	p
Pitta brachyura	Pittidae	Indian Pitta	p					p
Galerida deva	Alaudidae	Sykes creasted Lark	p			p
Eremopteirx grisea	Alaudidae	Ashy crowned sprrow lark	p			p
Mirafra cantillans	Alaudidae	Singing bush lark	p			p		p
Hirundo daurica	Hirundinidae	Rea rumped Swallow	p			p		p
Hirundosmithii	Hirundinidae	Wire tailed Swallow	p		p	p		p	p
Oriolus oriolus	Oriolidae	Eurasian golden Oriole	p			p		p
Oriolus xanthornus	Oriolidae	Black headed Oriole	p
Dicrurus macrocerrcus	Dicruridae	Black Drongo	p		p	p		p	p
Dicrurusparadiseus	Dicruridae	Racket tailed Drongo	p		p	p		p	p
Gracula religiosa	Sturnidae	Hill Myna	p
Acridotheres tristis	Sturnidae	Common Myna	p		p	p		p	p
Corvus macrohynchos	Corvidae	Jungle Crow	p
Dendrocitta vagabunda	Corvidae	Indian treepie	p					p
aegithina tiphia	Campehagidae	Common Lora	p					p
Chloropsis aurifrons	Lrenidae	Goldn fronted Chloropsis	p					p
pycnonotus jocosus	Pycnonotidae	Red whiskered Bulbul	p		p	p		p	p
Pycnonotus cafer	Pycnonotidae	Red vented Bulbul	p		p	p		p	p
Turdoides affinis	Muscicapidae	White headed Babbler	p					p
Terpsiphone paradisi	Monarchinae	Paradise Flycatcher	p					p
Prinia socialis	Muscicapidae	Ashy Prinia	p					p
Copaychus saularis	Muscicapidae	Magpie Robin	p			p		p
Saxicoloides fulicata	Muscicapidae	Indian Robin	p			p		p
Anthus rufulus	Motacillidae	Paddyfield Pipit	p					p
Motacilla maderaptensis	Motacillidae	Large Pied Wagtail	p			p		p
Nectarinia asiatica	Nectarinidae	Purple sunbird	p			p		p	p
lonchura malacca	Estrildidae	Blackheaded Munia	p			p		p	p
Lonchura punctulata	Estrildidae	Spotted Munia	p			p		p	p
Tyto alba	Tytonidae	Barn Owl	p
Tyto capensis	Tytonidae	Grass Owl	p
Gallus soneratii	Phasianidae	Grey Junglefowl	p					p
chalcophaps indica	Columbidae	Emerald Dove	p
Myiophonua horsfieldii	Muscicapidae	Malabar Whistling Thrush	p			p
Monticoka solitarius	Muscicapidae	Blue Rock thrush	p			p		p
Parus major	Paridea	Great Tit	p			p		p	p
Motacilla Flava	Motacillidae	Yellow Wagtail	p			p		p	p
Ploceus philippinus	Passeridea	Baya Weaver	p			p		p	p
Passer domesticus	Passeridea	House Sparrow						p	p
Pericotus flammeus	Campehagidae	Scarlet minivet	p
Total birds-		123