The influence of developmental stages and protective additives on cryopreservation of surf clam (Spisula sachalinensis) larvae.

This study was performed to find out the optimal larval stage and the most desirable protective additives for cryopreservation of surf clam, Spisula sachalinensis larvae. The survival rates of frozen-thawed larvae increased with post developmental stage. The highest value of 96.1 +/- 1.0% was achieved using umbo stage larva as developmental stage and 0.2 M sucrose as protective additive.

Study of carbohydrate metabolism in selected tissues of freshwater mussel, Lamellidens marginalis under copper sulphate toxicity.

Sublethal toxicity of copper sulphate on carbohydrate metabolism was studied in selected tissues of freshwater mussel, Lamellidens marginalis. Levels of glycogen and pyruvic acid decreased while lactic acid showed an increase. Activities of LDH, SDH and MDH decreased while G-6-PDH activity increased. There appears to be a shift in the carbohydrate metabolism from aerobic to anaerobic type due to toxicity of copper.

Oxygen uptake and filtration rate as animal health biomarker in Lamellidens marginalis (Lamarck).

The freshwater bivalve, L. marginalis was experimentally exposed to 10 and 30 ppm concentrations of CdCl2 to examine filtration rate, oxygen uptake and glycogen level of liver and gills for health assessment for their reuse in the reclamation of cadmium intoxicated environments. In situ experiment was also performed for better appraisal of the filtration rate in the lake. Oxygen uptake in the treated group exceeded that of control by 15-22% during the early 24 hr after cadmium exposure, but followed an essential decline (23-30%) thereafter. The reduction of filtration rate ranged from 12-62% in laboratory to 83-85% in field trials. At the tissue level, glycogen content was reduced by 61-72% in liver and 52-63% in gill. In both tissues, glycogen content was inversely proportional to the cadmium contents of the animal. Critical appraisal of data suggests that the threshold values of cadmium in gill and liver were 50-80 microg/g dw for oxygen uptake and 50-60 microg/g for filtration rate because of marked reduction of these parameters beyond the values of cadmium. It is concluded that filtration rate, oxygen uptake of the freshwater bivalve, L. marginalis can be used as biomarker for animal health assessment and for possible reuse of the stock animals.