Lipid composition of the zooxanthellate larvae of the brooding scleractinian coral Porites cylindrica

Abstract

Porites cylindrica is a brooding zooxanthellate scleractinian coral in northwestern Philippines. Little is known of its early life stages, hence this study aims to determine thelipid content and composition of the P. cylindrica larva. The paper focused on the variation of its larval size and lipid energy reserves during different days of planulation. Larvae were collected and measured during the peak of its release, 2nd to 4th day of planulation. Mean average length, 670 ± 170.1 µm and width of 230 ± 41.9 µm, and mean larval volume 0.01859 ± 0.00314 mm3 were found to be insignificantly different during the different planulation days. Lipid quantification revealed that the larvae of P. cylindrica contains 6.41-11.79% lipid per dry weight. Since lipid content is a predictor of energetic loading, this relatively low amount of lipid content further supports the short competency period (56-68 hours) in this species. In the identification of lipid classes, two out of four bands in the TLC chromatograms were identified as sterols and triacylglycerols (TAGs), while wax esters (WE) and fatty acids (FAA) were not detected. Triacylglycerol (24.91-46.29 % per total lipid), a source of energy for short-term metabolic needs, was found to be more abundant than sterols (0.19-0.36 % per total lipid). This reaffirms the findings from previous studies that brooding corals with zooxanthellate larvae contain more TAGs than other lipid classes.