Food habits of fiddler crab, Uca annulipes as indicated by fatty acid markers on intertidal flat of Setiu Wetland, Terengganu

Abstract

A study on the food habits of fiddler crab, Uca annulipes from the intertidal flat area of the Setiu Wetland, Terengganu was done using fatty acid biomarkers. The sampling was done two times, October and December 2007. The lipids contents and fatty acid compositions in the tissues and the crabs was compared with its food pellets and faeces, as well as in the surface sediments. The mean concentrations of total lipids were highest on December (16.95%). But the total lipid concentration is lowest on the same month for tissues samples (1.38%). Total lipid concentration in faeces is much higher than others ( 15. 98%) in October. Fatty acid content of the total lipid components was lower in October than in December. In December the difference between fatty acid content and other components is very high. The mean concentration of FAMEs was significantly higher in the feces (7.72-34.00 mg g- 1 ) than in crab tissues, food pellet and suface sediment. F AMEs content was higher in October rather than December except for faeces samples. The fatty acid profiles was also differ significantly between October and December (P<0.05) and between food pellets, surface sediments, tissues and faeces. All fatty acid markers found were mostly in line with what had found by previous study to indicate food habits of fiddler crabs. Analyses of the fatty acid compostion in the surface sediments, food pellets, tissues and faeces samples yield to the dominant fatty acid composition and small quantities of ce1tain fatty acid. The fiddler crab itself and other organic matter around its habitat could indicate the food sources utilization seasonally.