Change of Form in the Clam Meretrix casta (Chemnitz) during Its Growth

207-208Changes of form has been studied by the method of index of shape (allometric relationship) in 3 size-groups of Meretrix casta from Athankarai Estuary near Mandapam and the marine fish farm of CMFRI. It has also been studied by rearing numbered seed-clams in the marine fish farm. M. casta changes its form in a more or less definite pattern with age suggesting that the change of form in this clam is essentially genotypic. The extent of the change of form, however, differs in individuals and is also influenced by environmental factors. It appears that in Athankarai Estuary, the clams of different sizes and accordingly different, ages tend to select the substratum best suited for their forms

Ascorbate absorption by live channel catfish as a function of ascorbate concentration, pH, and-duration of exposure

Ascorbate uptake by muscle tissue of live channel catfish was affected by ascorbate concentrations (1000, 2000, and 3000 ppm), pH (5, 6, and 7) and duration of exposure (8, 16, and 24 hr.). The most favorable conditions for ascorbate absorption were exposure to 3000 ppm ascorbate at pH 5 for 24 hr. The increased muscle ascorbic acid concentration was 4-fold higher than that of the control group (10 ppm). The ability of live channel catfish to absorb dissolved ascorbate via gills and/or intestines and distribute the antioxidant into muscle tissue provides a new approach to introduce water-soluble antioxidants to aquacultured fish species