Food source of benthic bivalve, anadara ovelis an indecated by fatty acid makers on intertidal flat of Setiu wetland, Terengganu

Abstract

The fatty acid composition in the tissue of Anadara ova/is from Setiu lagoon, Terengganu in September and October was compared with those in sediment and suspended particulate material (SPM) in order to determine the avaibility of food source in environment. Microalgae ( diatom and dinoflagellate) contribute to the main food source of bivalve diet with high mean percentage in tissue during both months (44.75 - 53.83%). High mean percentage of microalgae in sediment suggests that the microalgae likely obtain by bivalve from the sediment resuspended in water column near the bottom surface. Copepod marker (20: 1 ro9) abundance in the tissue of bivalve contribute to the food source of bivalve beside microalgae. A. ovalis live in the intertidal flat nearby mangrove area. The fatty acid 18: 1 ro9, 18:2ro6 and 18:3ro3 found in the tissue indicate the consumption of mangrove detritus derived from adjacent area. The bacteria (18:lro7 and odd-branch fatty acid) which attached to mangrove detritus also contribute to the food source of bivalve but only small in number (2.49 - 5.13%). The macroalgae marker (18:2ro6 and 18:3ro3) also present in tissue but small in number. A viability of macroalgae at the mangrove area is limited due to low intensity of light. Therefore, the present of these fatty acids in the tissue of bivalve (2.48-3.75%) could indicate other food source such as the seagrass detritus.