Metals in coastal zooplanktons - A coastal living resource hazard

Abstract

Trace metals in zooplankton and in coastal water column were monitored in the shallow coastal parts of Bay of Bengal during one winter monsoon. Among the zooplankton biota, copepods remained the most dominant one, followed by Chaetognaths, ostracods and euphausids. The trace metals were generally low in water column and in the zooplanktons, except in the vicinity of two major ports. The metal content trend in the zooplankton had a decreasing tendency as Fe>Zn>Mn>Cu>Ni>Co>Cd>Cr>Pb. The concentration factor of metals in zooplankton are present in the decreasing order of Fe, Zn, Co, Cd, Ni, Cu, Mn & Pb. The iron content in zooplankton (50962 ppm) and in water column (2.81 ppb) in major harbour areas was nearly twice of the other coastal stations. The high concentration of lead (20 ppm) in the coastal zooplankton indicated the impacts of the high influxes of lead. The high manganese concentration in zooplankton (552 ppm) is hinting towards land drainage and of domestic sewage. The higher copper content in zooplankton (78 ppm) and zinc (7066 ppm) point out the close relationship between the pollution of the harbour and industrial effluents and domestic sewage. The observed enrichment of trace metals in water and in zooplankton at the open ocean stations are linked to bioaccumulation. The biological concentration factor and metal contents in zooplankton is appreciably varied for all the elements except for iron and zinc. The above findings clearly indicates the importance of bioavailability of metals in seawater and to the relative enrichment of heavy metal accumulation by planktonic species.