Some observations on the backwater clam, Meretrix casta (Chemnitz) in the Beypore and Korapuzha estuaries

Abstract

The backwater clam, Meretrix casta (Chemnitz), is a bivalve mollusc of considerable commercial importance and occurs in estuaries and backwaters of both the east and west coasts of India. Any biological study of this species will therefore be of interest from the scientific and also the fisheries points of view. Before the 'fifties Hornell's work seems to be the only instance in the country, of any considerable interest in this species (Hornell, 1917 and 1921) both from a systematic and the economic points of view. In 1953 Abraham made some detailed studies on certain aspects of the biology of the species including a study of the environment and also the growth rate under natural as well as experimental conditions, based on material from the Adyar waters near Madras. More recently, Durve (1963 and 1964) made some detailed investigations on the rate of filtration, gonadal changes and spawning behaviour in the species at Mandapara and Durve and Dharma Raja (1965) have also studied the dimensional relation in this clam from two localities at Mandapam and also the probable change of form with growth in one locality (1968). Reddiah and Mammen (1966) have described the copepod parasites of M. casta from Adyar. While all this work and the earlier observations of Hornell related in detail to the east coast material, not much work of a biological nature has so far been published on this species from the west coast, though Hornell has considered the west coast also for his systematic researches. Silas and Alagarswami (1965) have studied a case of parasitism by the peacrab (Pinnotheres sp.) on this clam at Malpe.