Ecosystem studies in Chilika Lake

With a surface of between about 900 and 1170 km2 Chilika Lake is the largest lagoon on the Asian continent and second-largest on a world-wide scale. It is situated on the east coast of Odisha, India, and is an ecologically but also economically and culturally important lagoon that has been recognized as such through the Ramsar convention for wetlands as of 1981. However, this wetland, with a unique biodiversity, home to the Irrawaddy dolphins and important wintering ground for migratory birds, has been subjected to increasing population and agricultural pressures in its catchment, which has had negative impacts on its ecology but also the economic and recreational activities, most notably the fishing industry over the past decades. To evaluate the health of the lagoon and to better understand the present and past environmental evolution of this ecosystem, the Faculty of Geosciences and Environment and UNIL has established an agreement for the exchange of researchers and students with KIIT-University in Bhubaneswar and the Chilika Development Authority of Odisha in India.
The aim of current research projects is to use a geochemical and isotopic approach to help evaluate the functioning of the present ecosystem and hence to assess the anthropogenic influence on this system. As such, the hydrological cycle of Chilika Lake is investigated using an aqueous geochemical and isotopic approach to constrain the water balance amongst the various inputs and drainage basins to this shallow lagoon (average depth of only 1.4 m) and hence the mixing of water. In conjunction with studies on the nutrient cycling that are based on chemical and isotopic compositions of carbon and nitrogen in the water column (plants, phyto- and macro-plankton as well as fish and sediments) the biogeochemical functioning of the ecosystem will be examined. The ecological evolution of Chilika Lake is recorded by the sediments deposited over time within the lake as it is directly related to the erosional and human, agricultural history as well as the climatic evolution within the catchment, all of which affect the sediment dispersal and accumulation within the lake. Furthermore, ostracods as sub-millimetre-sized crustaceans and abundant foraminifera are known to be sensitive ecological indicators and their abundance as well as geochemical and isotopic composition are indicators of oxygenation, salinity, and temperature of the water column in marine and brackish systems; hence they may also help interpret past ecological changes.

Chilika Lake

 

Participants: Prakash Kumar Sahoo, Laurent Decrouy, Jorge Spangenberg, Torsten Vennemann
Masters students: Géraldine Bourgeois, Kelly Delavy, Michèle Ecuyer, Caroline Hostettler, Pauline Lange

 

Typical recent publications
Decrouy L., Vennemann T.W., and Ariztegui D. (2011). Controls on ostracod valve geochemistry, Part 1: Variations of environmental parameters in ostracod (micro-)habitats. Geochimica et Cosmochimica Acta, V.75, p. 7364-7379.
Decrouy L., Vennemann T.W., and Ariztegui D., (2011). Controls on ostracod valve geochemistry: Part 2. Carbon and oxygen isotope compositions. Geochimica et Cosmochimica Acta, V.75, p. 7380-7399.

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