Morphology, Biochemistry and Distribution of Villorita cyprinoides and Meretrix casta (Bivalve) Shells in Vembanad Estuary, Kerala, India

Abstract

Estuaries are among the most commercially significant ecosystems on the earth, and they provide different habitats for numerous bivalve species. The Clams are one of the most widely distributed and used aquatic bivalves, providing much more protein-rich food than mussels and oysters. The Vembanad Estuary is one of the richest clam fisheries coastal wetland in Kerala. The present study focusing on comparatives ofmorphology and biochemistry of Villorita cyprinoides and Meretrix casta shells in Vembanad Estuary. It also attempts to understand the variations in clam distribution caused by salinity fluctuations and sediment texture. According to the morphological and morphometric analysis, medium size shells were found in greater abundance in both species. Atotal of 306 shells of V. cyprinoides and 169 shells of M. casta were obtained from the ten sample locations of Vembanad Estuary. The density of V. cyprinoides shells (192) was higher in the southern part while the northern portion of Vembanad Estuary represented by M. casta shells (108) with comparatively lower density. V. cyprinoides has a negative linear correlation with salinity, as indicated by R2 of 0.96. M. casta, on the other hand, exhibits a positive correlation with salinity, with 0.94 linear coefficient. V. cyprinoides was more prevalent in clayey and silty sediments, while M. casta was more common in sandy sediments. The X-ray Fluorescence (XRF) analysis showed that the Calcium Oxide percentage of V. cyprinoides and M. casta shells were 39.47% and 38.72%, respectively, while all other metal oxides were present only in trace amount. Keywords: Bivalves, Villorita cyprinoides, Meretrix casta, Major Oxides, Vembanad Estuary