Results & 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 with the scope for 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.

3.1 Demarcation of study area and quantification of ecosystem goods and services from the estuarine ecosystem: The Aghanashini estuary with a spatial extent of 4801 ha is the largest estuary in Uttara Kannada 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 et al. 2017a; Bann 2003; Barbier et al. 2011; Costanza et al. 1997; Costanza and Folke 1997; MEA 2005) as (i) provisioning, (ii) regulating, (iii) supporting and (iv) information services.

3.2 Provisioning services

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 2.1. 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 2.1: Estuarine fisheries value

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 2.2. 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 2.2: Goods from Estuarine Agriculture

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 2.3.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 2.3: Estimation of Revenue from Mining activities

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 2.4 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 2.4: Estimation of Net income from Mangrove product harvesting

3.2.5 Salt from estuaries: Table 2.5 shows that salt production in the Aghanashini estuary of Uttara Kannada is about 50 million Rs. per year and this traditional enterprises are at Gokarna, Aghanashini where (Bhat et al. 2010).

Table 2.5: Salt production in the estuarine catchment

3.2.6 Transport: Table 2.6 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 2.6: Revenue from Water transport and Port activities

3.2.7 Total provisioning services: Provisioning services quantification through the compilation of all direct benefits for each estuary is given in Table 3. 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 3: Provisioning services from Estuaries, Uttara Kannada

3.3 Indirect uses

The indirect uses of estuarine ecosystem consist of the Regulating services, Supporting services and Information services (Bann 2003; Barbier et al. 2011; Costanza et al. 1997; Costanza and Folke 1997; MEA 2005; Ramachandra et al. 2017a; Sahyadri 2018; TEEB 2011; UNEP 2013; NEP/GEF 2007). Table 1 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, remediation, climate regulation, gas regulation, water supply, nutrient retention and cycling, natural hazard mitigation, ground water recharging and oxygen provision. Table 4 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 4: Services and goods of estuaries

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 5 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 5: Supporting services from Estuaries in Uttara Kannada

3.3.3 Information services: The information services include recreation, cultural and artistic information, science and education and the values are given in Table 6.

Table 6: Information services from Estuaries in Uttara Kannada

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 given in Table 7, highlights that the Aghanashini estuary is highly productive ecosystem with the total value of 24.03 billion Rs/year and the annual productivity of 5 million Rs/hectare/year. Provisioning service makes up the 23% of the total value. Information service share is about 2%, while regulating and supporting services are respectively 37% and 39%.

Table 7: Total Economic Value of Estuarine Ecosystem in Uttara Kannada