Toxic effects of ammonium sulphate on the gills and gut of the edible cockle Anadara antiquate (Bivalvia;Arcidae)

Toxicity of ammonium sulphate has not been established for most marine organisms in Tanzania. The present study has established the toxicity of ammonium sulphate on the edible cockle Anadara antiquate (Bivalvia,Arcides). The LC50 of this toxicity is 271 mg/L at 95% significance as estimated in vitro in a 96h static bioassay with mean values of pH 8, temperature 25C, salinity 33% and DO>60% of the saturation limit. In three replicates, eight samples of A.antiquada were exposed to 50, 80,130,200,300,400, and 600 mg/L of ammonium sulphate concentrations for 96h. Estimation of LC50 was coupled by stress and histopathological characterization of the gill and intestine. Although toxicity was not significantly acute within the exposure time of 96h, it induced massive deformities that persisted over a two week period in the bivalves. This post-exposures persistence of ammonium sulphate toxicity promoted mortality to 100% at a concentration of 200 mg/l and higher. Toxicity was accompanied by excessive shell gaping, foot protusion, mucus secretion, necrosis, hyperplasia, cilia shortening, lamellar shrinkage, epithelium disruption and abscess formations and eventual ruptures. Moreover, the bivalves showed impaired mobility and sensitivity, leading to death. Nevertheless, cockles that survived a 96h exposure when assessed up to 336h showed complete remission from the toxic effects and this was an indication of absence of chronic toxicity.