Eutrophication induced changes in benthic community structure of a flow-restricted tropical estuary (Cochin backwaters), India

• DOI: 10.1007/s10661-010-1594-1
• Publication Date: 2010-07-16T03:12:47Z
• Authors: G. D. Martin; P. A. Nisha; K. K. Balachandran; N. V. Madhu; M. Nair; P. Shaiju; T. Joseph; K. Srinivas; G. V. M. Gupta
• Keywords: Pollution assessment; Chlorophyll; 0106 biological sciences; Principal Component Analysis; 550; Chlorophyll A; India; Eutrophication; Macrobenthos; Invertebrates; 01 natural sciences; Carbon; 6. Clean water; 13. Climate action; Animals; 14. Life underwater; benthic community; Environmental Monitoring

The influence of anthropogenic loading on the distribution of soft bottom benthic organisms of a tropical estuary (Cochin backwaters) was examined. The industrial activities were found to be high in the northern and central part of the estuary, where dissolved inorganic nitrogen (DIN > 210 μM) and phosphorus (DIP > 6.5 μM) have caused high abundance of chlorophyll a (up to 73 mg m(-3)) and accumulation of organic carbon in sediments (up to 5%). Principal component analysis distinguished three zones in the estuary. The central zone (Z1) was characterized by organic enrichment, low species diversity, and increased number of pollution tolerant species. Long-term deterioration of the estuary is indicated by an increase in the nutrients and chlorophyll a levels by sixfold during the last few decades. Flow restrictions in the lower estuary have lead to a fourfold increase in sediment organic carbon over the period of three decades. The reduced benthic diversity followed by an invasion of opportunistic polychaetes (Capitella capitata), are indicative of a stress in the estuary.