THE ZOOPLANKTON COMMUNITY AND ITS RELATIONSHIP WITH ENVIRONMENTAL VARIABLES IN A HIGHLY POLLUTED SYSTEM, GOLDEN HORN, TURKEY

Abstract

The Golden Horn Estuary (İstanbul) nutrient-rich, eutrophic and turbid at the inner part based on discharges from Alibeyköy and Kağıthane creeks. The pollution had been drastically increased by the accretion in the industry and ur-ban development around the estuary since 1950s. The Golden Horn rehabilitation project was carried out during the 1998-2002 period. The present study was conducted following the rehabilitation process between November 2002-October 2003 at selected four stations, three at the in-ner part and one at the middle part of estuary. This is the first study on zooplankton community in the Golden Horn Estuary. The seasonal variation of zooplankton composition and density and 14 environmental variables (temperature, salinity, Secchi disc depth, turbidity, pH, dissolved oxygen, carbonate, bicarbonate, calcium, magnesium, total hardness, NO2-N, NO3-N, o-PO4) and Chlorophyll-a concentration, which indicates the intensity of life in the Golden Horn Es-tuary have been studied, monthly. A total of 29 taxa was identified. Zooplankton composition was characterized by freshwater, estuarine and marine species. Zooplankton of Golden Horn Estuary was composed mainly by holoplank-tonic organisms (53% of the total), with Copepoda as the most abundant group and a high number of taxa. Diversity were higher at all stations. A distinct relationship between zooplankton taxa composition and their environment, deter-mined by a redundancy analysis, indicated that the measured environmental variables contributed to the variations in the zooplankton community structure to some extent. Four envi-ronmental variables and Chlorophyll-a explained 73.7% of the variation in the taxonomic structure. The results showed, that distribution of zooplankton was significantly associated total hardness, NO2-N, NO3-N, temperature and Chloro-phyll-a (p<0.05).