In an alarming finding, as many as 59 benthic species are missing from the backwaters of Kochi proving that the estuary is fast getting degraded. This calls for a wise management for the survival of flora and fauna.
A survey of five selected stations indicates the importance of conservation measures to save the ecosystem based on the samples taken in 2004.
The benthos refers collectively to all aquatic organisms, which dwell in, on or near the bottom of water bodies. They are used to assess overall estuarine health. The macrobenthos consists of the organisms that live at the bottom of a water column and are visible to the naked eye.
The study was to trace the bio-diversity change that might have occurred over a period of three decades from 1974.
As many as nine species have been identified as the new invaders to the system in the survey done by Feebarani John under the guidance of R Damodaran of School of Marine Sciences, Cochin University of Science and Technology.
Long-term changes in the macrobenthic diversity of the estuary were investigated to assess the overall estuarine health. The analysis showed that among benthos, at present polychaetes constituted the major component with 29 species. Crustacea is the second dominant group with 12 species. The mollusca stands at the third position with four species.
Comparison of present data with that of previous studies revealed striking differences in the community structure of benthos.
Among the missing 59 species (that were once present in the estuary), 25 were polychaetes, 17 crustaceans and 17 comprised molluscs.
“The absence of the species can be the result of large-scale dumping of organic and inorganic waste into the water bodies. Moreover, some of the new invaders can tilt the balance of the ecosystem. It may have come through various sources. Some might have reached here by clinging on to the ships or heavy logs of wood,” said Feebarani John.
The study points Muculista senhosea, one of the new invaders to the system, will form thick mat over the bottom, preventing the growth of other benthos.