粗珪酸を指標とするアコヤガイの濾過水量と摂餌量の測定法について

Abstract

It is well known that lamellibranchs are very sensitive to disturbance and changes in the environmental condition and that they react by sl owing down or even stopping the water transport. In most investigations into lamellibranchs, filtering rates measured under laboratorical conditions tend, therefore, to be lower than under natural conditions. Thus, the purpose of the present investigation is to determine the filtering rate of the pearl oyster, Pteria (Pinctada) martensii DUNKER, under normal environment, namely, in the sea. The authors have employed the crude silicate as an indicator since it is much contained in suspending materials and in faeces. Moreover, the silicate is relatively stable in the process of the digestion (Table 2). Filtering and feeding-rate were calculated formula (1) and (2). Filtering rate (liter)=Amount of insoluble crude silicate in faeces of peral oyster/Amount of insoluble crude silicate in one liter sea water (1) Feeding rate of pearl oyster=Filtering rate×Amount of suspending matter in one liter of sea water (2) Approximate estimation of filtering rate from crude silicate method was 24-352l/one pearl oyster/one day (average, 167l in Matoya Bay). These values are two times higher than the results of generally used methods (Table 4). In this experiment, the feeding rate (as dry matter) ranges from 63-774mg/one pearl oyster/one day (average, 380mg in Matoya Bay) (Table 3).