Mangroves: in Need of Estuary-based Management Plans

Subash Chandran MD and Ramachandra TV
Centre for Ecological Sciences
Indian Institute of Science, Bangalore- 560012
mdschandra@yahoo.com , cestvr@ces.iisc.ernet.in

Mangroves play crucial role in coastal productivity and environmental functioning; yet their role is wanting in realistic appreciation. Here is given present picture of mangrove management which lacks approach harmonized with complexities of ecology of individual estuary.   India, though rich in mangrove diversity, is also encumbered by lack of comprehensive, habitat specific management plans for estuaries and creeks which are also under tremendous anthropogenic pressures. The flaws in management systems are examined and need for estuary-specific mangrove action plans emphasized. Locality-specific mangrove action plans need to evaluate ecosystem functioning, estuarine history, tidal dynamics, hydrology, soil features, and salinity fluctuations and setting up goals of management. Suitable areas and proper combination of species for planting, including re-introductions and de novo introductions, are to be identified. Community and local institutional participation are desired for program success.

Sea turtles: Ocean’s ambassadors of conservation

Kartik Shanker
Centre for Ecological Sciences,
Indian Institute of Sciences, Bangalore 560012, India

There are seven species of sea turtles in the world, of which five –olive ridleys, leatherbacks, loggerheads, hawksbills and green turtles- are found in India. Olive ridley turtles nest throughout the mainland coast of India. Leatherbacks, hawksbills and green turtles nest in the Andaman and Nicobar Islands. Of Course, the best known nesting ground for sea turtles in India are in Orissa, where thousands of olive ridley turtles make their way to the offshore waters of Gahirmatha, Devi River mouth and Rushikulya, where the congregate and mate. Mass nesting, where as many as hundred thousand turtles nest simultaneously within a few nights, usually occurs between February and April, at one or more of these sites. Sea turtles have faced a number of threats worldwide, leading to the decline and extinction of many populations. They have been exploited for their meat and shell, and many eggs and hatchlings are eaten by feral predators such as dogs and crows. Many indirect threats such as habitat loss, pollution also affect them. Many sea turtles get accidentally caught in a variety of fishing nets, especially trawl and gill nets, and drown and die. In India, there are many conservation groups that are in trying to save sea turtles, including fishermen, students, biologists and government departments.

Bivalve’s diversity and distribution in relation to salinity

Boominathan M, Subash Chandran MD and Ramachandra TV
Energy & Wetlands Research Group, Centre for Ecological sciences
Indian Institute of Science, Bangalore 560 012
E Mail: cestvr@ces.iisc.ernet.in, boomi@ces.iisc.ernet.in, mds@ces.iisc.ernet.in

Bivalves living in the estuaries are termed as euryhaline; they can able to live in the large changes in salinity level. Their distribution varies with respect to changing substrate composition, water quality, notably with regard to salinity in the estuary. Studies reveal the relationship between salinity gradient with occurrence of bivalve species in the Aghanashini estuary, West coast, Karnataka. Bivalve diversity and distribution data obtained from the field survey conducted for 10 months. Data analysis reveals that out of nine bivalve species seven species inhabits the region where the salinity is close to sea water. While species such as Vellorita cyprinoids prefers freshwater and tolerate salinity upto 30 ppt. Katelysia opima inhabits from 32 ppt to salinity close to seawater.

Tsunami impact and morphological changes along the Tamil nadu coastal esturaies

Anand PH and Ramakrishnan N
Reader in Geography, Reader in Botany,
Government Arts College (Autonomous), Kumbakonam-612 001

The proposed research would study the Morphological Changes along the East coast river mouth which are widened due to impact of Tsunami. East coast is severely affected due to Tsunami of 26th December 2004 and several morphological changes along the coast happened. There are numerous Major and Minor rivers that mixes with the sea in this region. All the mouths of the rivers are affected due to Tsunami. Apart from the river mouth affected there has been severe impact through out the World. In India sever impact is felt at Nagapattinam district that caused a death of about 6000 lives and loss of several millions. Next to Nagapattinam district, Cuddalore district is worst affected district. Tsunami has caused extensive damages in Andaman and Nicobar Island, Andrapradesh, Kerala and Pondicherry State. The death toll had exceeds about ten thousand in India. The Tsunami disaster also raised important question about the effectiveness of human societies in dealing with such extreme high magnitude in terms of preparedness, the effectiveness of warning system and the ability of the international community to act unilaterally to guide and organize an effective response. River mouths are usually covered with sand, Mangrove forest, and Vegetation cover, Swamps and in some cases settlement. The river mouth, which could not resist the force of Tsunami wave, had suspected greater changes. This necessitates a several changes along the coast and various destructions by using optical remote sensing technology. The GPS would used to map the changes at the river mouth through survey method. The study would suggest measures to overcome the problem due to changes in the river mouth due to Impact of Tsunami. Using the optical remote sensing data and the filed data to create a Geographical information system model for disaster reduction in future would generate a geo-spatial data.

Grain Size Variations and Environmental Implications in a Coastal Ecosystem – A Case Study

Purandara BK¹, Venkatesh B¹ and Choubey VK^2
1Scientist, Regional Center, National Institute of Hydrology, Hanuman Nagar, Belgaum – 590 001
²Scientist.F, National Institute of Hydrology, Roorkee, Uttarakhand

The determination and interpretation of particle grain-size has a fundamental role in hydraulics, geomorphology and sedimentology. The study of textural parameters of the sediments is of paramount utility in differentiating various depositional environments. The present study is carried out along the Central Kerala coast. Grain-size data have been collected from various sources. Apart from collected data, few representative surface sediment samples from the downstream of important rivers like Pamba, Manimala, Muvattupuzha, Minachil and Periyar which debauches into Vembanad lake have been collected. Surface and suspended sediment samples were also collected from the Vembanad lake area where the rivers join the lake and the adjacent nearshore area. Beach sediments were also collected from the selected locations. The study revealed a systematic change in grain-size pattern from moving from one environment to another. Coastal waters showed significant quantities of suspended sediment which resulted in the formation of mud banks (wave dampening). It is also observed that the accumulation of finer sediments aid in protecting the coast during southwest monsoon season. A socio economic survey has been conducted in the study area to know the importance and significance of the rare coastal phenomena known as mud banks. Mud banks acts as a treasure house for fishes.

Trace organics in sediments in the lower stretch of Ganges estuary and their exotoxicological significance

Santosh Kumar Sarkar
Department of Marine Science, University of Calcutta, 35, B.C. Road,
Calcutta 700019, India;
Email: sarkar.santosh@gmail.com

Persistent organic polltants (POPs) are of global concern due to their widespread occurrence, persistence, bioaccumulation and toxicity to animals and human. The paper critically examines the recent contamination status, distribution and potential pollution sources of these trace organics such as HCH(hexachlorocyclohexane) isomers(HCHs), DDT(dichlorodiphenyltrichloro ethane) and its metabolites (DDTs), HCB(hexachlorobenzene) and congeners of PCBs(polychlorinated biphenyls) and PAH(polycyclic aromatic hydrocarbons) in surface sediments (<63µm) from the lower stretch of Ganga River Estuary, eastern part of India. Sedimentary organic carbon and textural properties were also analyzed in order to assess the role of geochemistry on the prevalent POPs contamination.
HCH, DDT, HCB, PCB and PAH were identified compounds in all the samples, whereas the concentrations of chlorinated pesticides (trans-epatochloroepoxide, dieldrin, endrin, metaoxyclor and mirex) were below the detection limits and were not of great concern. The pesticides did demonstrate markedly different distributions reflecting different agricultural and domestic usage in the region. An overall elevated level of HCB, DDT and PCB were recorded at Babughat adjacent to the metropolitan mega city Calcutta. The concentration of four important isomers of HCHs reveals a heterogenic distribution where beta and gamma HCH shared the dominant part of total HCH than the alpha and delta isomers. This may be relative to bio-isomerization of HCHs during the process of transformation in these estuarine regions. The relative low percentage composition of alpha HCH is because this congener has a high vapor pressure and Henry’s law constant and therefore is readily lost. Low alpha/gamma ratio in the sediment samples was observed which might be due to microbial degradation. Unlike HCH and DDTs, the concentration of HCB did not show any sharp spatial variation. The prevailing sequence of DDT metabolites indicates an active degradation of the parent compound in he sediments and/or inputs of already degraded pp’ DDT to the region. Peak concentrations of HCH isomers and DDT metabolites have the potential to induce exotoxicological impact as per the sediment quality guidelines.
Concerning the PCB congers, tri-chlorinated biphenyls (CB), to octa-CB were detected in the sediment samples. The general decreasing order of seven dominant PCB congeners’ contribution to the total load was: PCB 138> PCB 153>PCB 149>PCB 101>PCB 118>PCB 141>PCB 151. This order can explained by the fact that lightly chlorinated PCBs are less persistent, have lower log kow  and are more volatile than heavily chlorinated PCBs. Therefore, heavily chlorinated PCBs such as penta, hexa and hepta- chlorinated are more accumulative in the sediments whish might be contributed from the commercial mixtures used in transformers, electric equipment and other industries in India, whereas lightly chlorinated PCBs are degraded and volatilized further.
Mean Σ₂₂PAH concentrations in the sediments ranged from 153 to 3242ng g^-1 dry weight, with an overall increase of the high molecular PAHs at the site situated at the sea face (Bay of Bengal). Perylene was abundant in the sediments, accounting up to ~ 55% of total PAHs which can be explained by active inputs of soil materials due to frequent strong rain in this tropical climate zone. A rather exception prevalence of high molecular weight PAHs was substantiated: nearly 80% of Σ PAHs include Perylene (11.26%), benzo (a) pyrene (2.32%) and benzo (g, h, i) Perylene (6.84%). Carcinogenic compounds were present in moderately high (BaP, BkF, BbF) or negligible and low concentrations (DBA, InP) in majority of the cases. The PAH diagnostic ratios indicated that the PAHs in the sediment core were of pyrolytic origin, and that atmospheric deposition and land runoff may serve as the important pathways for PAHs input to the sediment. Fluranthene and Pyrene, the dominant four-ring PAHs, also showed abrupt elevated concentrations at Babughat.
The observed molecular ratios (phenanthrene to anthracene (Ph/An) and fluranthene to pyrene (FI/Py)) substantiated origin of PAHs from pyrolytic processes due to high combustion inputs and urban runoffs from the urbanized areas. Carcinogenic compounds such as benzopyrene, benzofluranthrene were dominant at some sites and total PAHs exceeded the effect- range low values implying occasional or frequent adverse biological effects. The total PAH levels were expressed as the benzo(a)pyrene B(a)P toxicity equivalents(TEQ_s^carc) and compared to contaminated sediments from Guba Pechenga, Barents Sea, Russia. The three different approaches chosen for risk assessment of the Ganga river sediments were the consensus SQGs obtained by TEC(Threshold effect concentration), PEC(Probable effect concentration) and EEC(Extreme effect concentration), the threshold/probable effect level (TEL/PEL) approach and finally, the ERL-ERM guidelines.
The authors strongly recommend for (i) regular and reliable monitoring of POPs in this fragile environment so that any exceedance in concentration over the ER-L values can be detected and an appropriate action can be taken and (ii) strong vigilance programme towards installation and maintenance of the waste treatment plants to check he flow of trace organics in the river water. An alarming situation has already been emerged due to presence of pesticide residues in the muscle and blubber in the gangetic dolphin (Platanista gangetica), the endangered cetacean mammal declared by the World Conservation Union (IUCN) and also in human milk in various parts of India.

Dissolved Methane in Relation to Important Nutrient Gradients in Surface Waters of Tapi Estuary, Gujarat

Shailendra Viyol and Nirmal Kumar JI^*
P.G. Department of Environmental Science and Technology,
Institute of Science and Technology for Advanced Studies and Research (ISTAR),
Vallabh Vidyanagar, 388 120, Gujarat, India.
*E. mail: istares2005@yahoo.com

Methane is one of the important greenhouse gases that contribute to a rise in global mean surface temperature due to their relatively high absorption of infrared radiation. Aquatic environments are postulated to contribute > 50% of the total global methane (CH₄) flux to the atmosphere. Methane concentration in surface waters of Tapi estuary, Gujarat, India was measured for short period, from January to July, 2008 in addition to important nutrient gradients like total organic carbon, dissolved oxygen, salinity, phosphate, nitrate and sulphate. The mean dissolved CH4 concentration for all water samples at ONGC Bridge (upper reaches) was 1236.04 nmol/l and at Dumas (lower reaches) was 764.48 nmol /l. The Dissolved methane values observed high at the upper reaches than the lower reaches. The positive correlation was found between dissolved methane and total organic carbon. On the contrary the negative correlation was observed between dissolved oxygen, salinity, phosphate, nitrate and sulphate and methane concentration. The probable causes for varying methane concentration at different reaches and nutrient gradients will be discussed in the paper.

Diatom Flora of Aghanashini Estuary mangroves, West coast of India

Smitha^#, Mustak M.S^#, Karthick B^*, Ramachandra TV^*
#Department of Applied Zoology, Mangalore University, Mangalore
^*Energy and Wetlands Research Group, Centre for Ecological Science,
Indian Institute of Science, Bangalore

Diatoms represent the most important organisms in the aquatic ecosystem. The exploration of diatom flora in taxonomic and ecological context provides enormous information about the habitat. In this attempt the diatom flora in the Aghanashini estuary were explored during Oct 2008. The diatom samples were collected from different habitats like roots of the mangrove, sediment and submerged grass. Rhizophora mucronata,
R .officulate, Avicennia officinalis, Acanthus ilicifolius, Cyprus sp. are the dominant mangrove vegetation in this estuary. Diatoms were identified up to genus level. Across all the habitats 30 genera were identified, among which 25 belongs to the pennate and 5 genera belong to centric forms. Nitzschia, Pinnularia, Gyrosigma, Navicula, Diploneis, and Melosira are the dominate diatom genera, all these genera were represented by more than 2 species. The investigation is in progress to identify diatoms at species level.