Application of Fatty Acids for Chemotaxonomy of Reef‐Building Corals

Abstract

Sixteen scleractinian species of six coral families (Acroporidae, Pocilloporidae, Poritidae, Faviidae, Pectiniidae, and Fungiidae) from Vietnam were analyzed for fatty acid (FA) composition. Except for the Poritidae species, total lipids of the corals had the same set of FAs, about 50% of them being unsaturated acids. Some coral families had high levels of characteristic FAs: 20:3(n-6), 20:4(n-3), and 22:6(n-3) in Pocilloporidae; 18:1(n-9) and 22:6(n-3) in Poritidae; and 18:3(n-6) and 22:5(n-3) in Faviidae. For the first time in hexacorals, unsaturated C(24) FAs (24:1(n-9), 24:2(n-6), 24:2(5,9), 24:3(5,9,17), and 24:4(n-3)) were discovered in the Poritidae species. The highest level of 18:1(n-7), odd-chain and branched FAs (7.5% in total) was detected in Sandalolitha robusta. The data obtained on the contents of ten principal C(18)-C(22) polyunsaturated FAs (PUFAs) for the 16 specimens were combined with data on the 19 reef-building coral specimens investigated previously and subjected to multidimensional scale analysis (MSA). The representative coral families (Acroporidae, Pocilloporidae, Poritidae, Faviidae, Dendrophylliidae, and Milleporidae) were separated by MSA according to the composition of their principal PUFAs. Therefore, PUFAs may serve as chemotaxonomic markers for reef-building corals at the family level. Family-specific compositions of coral zooxanthellae characterized by different PUFA profiles, which affect the PUFA content of whole coral colonies, were supposed to be the probable cause of the discovered chemotaxonomic distinctions between reef-building corals.

Distribution of lipids and fatty acids in corals by their taxonomic position and presence of zooxanthellae

“…Our present (Fig. 3) and previous results (Imbs et al 2007a) showed that at least 5 scleractinian families (Acroporidae, Faviidae, Fungiidae, Pocilloporidae, and Poritidae) had a distinct PUFA composition. In spite of lipid variations caused by food sources, coral species within of some scleractinian families, and even some genera, had similar metabolisms and accumulation of PUFA.…”

“…Recently, the set of 10 PUFA was successfully used as PCA variables for chemotaxonomic investigations of reef-building corals (Imbs et al 2007a). ANOVA tests for each possible pair from the 4 families indicated that there were no differences (p > 0.05) in 20:4n-6, 18:3n-6, and 18:4n-3, but most of the pairs differed in C 18 -20 monoenoic FA.…”

“…Multivariate analysis of the unsaturated FA selected has been recently applied for this classification (Imbs et al 2007a). The correlation between unsaturated FA and taxonomic position of scleractinians was evident (Fig.…”

“…After the first attempt of wide screening of reef-building corals (Meyers 1977), several reliable comparisons of FA compositions of scleractinians and soft coral have been performed (Latyshev et al 1991, Carballeira et al 2002, Imbs et al 2007a. The first modern simultaneous investigation of lipid class and FA composition of Okinawa cnidarians was made by Yamashiro et al (1999).…”

“…The first modern simultaneous investigation of lipid class and FA composition of Okinawa cnidarians was made by Yamashiro et al (1999). Recently, we have shown that several FA sets are useful for the chemotaxonomic studies of reef building and soft corals (Imbs et al 2007a. Unfortunately, most studies of FA composition in corals have examined only a single reef-building species.…”