Population Density, Biomass, Secondary Productivity, and Length-Weight Relationship of Mangrove Clam Geloina expansa (Mousson, 1849) in a Mangrove Forest of Sto. Tomas, La Union, Philippines

The mangrove clam (Geloina expansa) is the most commonly collected bivalve species in the mangrove area of Brgy. Ubagan, Sto. Tomas, La Union, Philippines, serving as both food and a source of additional income for nearby residents. This study aimed to determine the population density, biomass, secondary productivity, and length-weight relationship (LWR) of G. expansa to provide valuable information on the status of the clam population in the mangrove area, which can serve as a reference for conservation efforts and potential aquaculture initiatives. The results revealed that the population density of G. expansa in the area was 1.78±0.83 individuals per square meter. The biomass and secondary productivity of the mangrove clam were 0.115g dried weight per month and 0.0257g per square meter per month, respectively. The LWR analysis showed that G. expansa exhibited a positive allometric growth pattern (b> 3), with the LWR equation being y = 3.3115x - 0.7804 and an r² value of 0.9785. The clay substrate type and high organic matter content in the mangrove area were favorable for the growth and survival of G. expansa. Ongoing monitoring and management are essential to preserving both the clam population and the mangrove ecosystem, ensuring the long-term sustainability of G. expansa and maintaining the ecological balance of its habitat.