Influence of environmental variables on the abundance of estuarine clam Meretrix casta (Chemnitz, 1782) in Trang Province, Southern Thailand

Abstract

The estuarine clam Meretrix casta (Chemnitz, 1782) is an edible bivalve that burrows into bottom sediment to protectitself from environmental fluctuations and predation. This study examined the relationship between clam populations andabiotic environmental conditions in order to develop an understanding of the biological and ecological processes that couldbe used to improve their management and exploitation. The study site was located in the estuary of the Palian River, KantangDistrict, Trang Province, on the Andaman coast of Thailand. Six zones were established along the estuary. Data werecollected from January 2008 to December 2008. The results showed that salinity (Sal) and concentrations of total suspendedsolids (TSS) were the water quality parameters most closely related to population densities of estuarine clams. The combinationof those variables gave the strongest correlation to clam densities (Spearman rank correlation, pw = 0.504). Among bottomsediment parameters, pH and ferrous and ferric iron concentrations gave the strongest correlations to clam densities(Spearman rank correlation, pw = 0.716). The result revealed that the water quality (Sal and TSS) and the bottom sediment(pH, ferrous and ferric iron) were the main significant parameters influencing the abundance of estuarine clam M. casta.

Keywords

• Estuarine clam
• Meretrix casta
• bivalve
• population
• environment