RESUMO
Gafrarium divaricatum were exposed to xylene (4.25 and 8.50 mg l-1), benzene (4.35 and 8.70 mg l-1) and gear oil-WSF (1 and 2%) for 30 days. Chronic exposure of clams to the pollutants resulted in loss of bubbling epithelium, reduction in cytoplasm volume and density, fusion of cell membranes and nuclei forming darkly stained area at basal part of the cells. Disintegration of basement membrane due to damaged epithelial cells, disruption of inner lining of tubule, formation of necrotic spaces, separation of epithelial cells from basement membrane, increase in internal luminar area, complete necrosis of epithelial cells as well as occurrence of cell debris in between the tissue were also observed in the clams due to chronic exposure of the toxicants.
RESUMO
In the present study, a survey of Mahim creek and Bay area was undertaken that indicated absence of fauna, particularly molluscs from the area, which was a repository in the past. During bioassay experiments of Mahim creek water, the clams G. divaricatum and C. antiquata could not open their valves in 100% creek water and died within 12 hrs of exposure. The 96 hrs LC50 values of Mahim creek water for G. divaricatum and C. antiquata were found to be 20% and 40% respectively during summer and 38% and 57% respectively during rainy season. When two sets of the clams were transplanted at Mahim creek, they died within 12 hrs. These experiments suggest the extreme level of pollution in the area. This level of pollution is responsible for transforming the area into barren locality in terms of fauna, specially the rich molluscan diversity. However, Gorai creek was found to be comparatively very less polluted and it still serves as breeding and nursery ground for various fishes and prawn species. Hence it must be protected and conserved.