title: Eutrophication induced changes in benthic community structure of a flow-restricted tropical estuary (Cochin backwaters), India.
abstract: 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.
authors.affiliation: National Institute of Oceanography (CSIR), Regional Center, P.B.No 1913, Cochin, 682018, India. martinnio@gmail.com
authors.forename: G D
authors.initials: GD
authors.lastname: Martin
authors.forename: P A
authors.initials: PA
authors.lastname: Nisha
authors.forename: K K
authors.initials: KK
authors.lastname: Balachandran
authors.forename: N V
authors.initials: NV
authors.lastname: Madhu
authors.forename: M
authors.initials: M
authors.lastname: Nair
authors.forename: P
authors.initials: P
authors.lastname: Shaiju
authors.forename: T
authors.initials: T
authors.lastname: Joseph
authors.forename: K
authors.initials: K
authors.lastname: Srinivas
authors.forename: G V M
authors.initials: GV
authors.lastname: Gupta
mesh_terms: D000818:Animals; D002244:Carbon / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D004784:Environmental Monitoring / Q000379:methods*; D005068:Eutrophication / Q000502:physiology*; D007194:India; D007448:Invertebrates / Q000254:growth & development* / Q000378:metabolism; D025341:Principal Component Analysis
chemical_list: D002734:Chlorophyll; D002244:Carbon; D000077194:Chlorophyll A