Seasonal and interannual variation of fatty acids in macrophytes from the Pacific coast of Baja California Peninsula (Mexico)

The fatty acid composition of macrophytes is usually quite stable among different taxonomic groups, and thus, several fatty acids can been used as biomarkers. However, variations between species can be affected by seawater temperature and other ambient factors. With higher annual temperatures, we expect less polyunsaturated fatty acids, and changes in the fatty acid signature of algae. Here we analyzed seasonal and interannual variations, in two species of red (Gelidium robustum and Gracilaria sp.), two brown (Eisenia arborea and Macrocystis pyrifera), and two green macroalgae (Ulva lactuca and Ulva sp.), and one species of seagrass (Phyllospadix torreyi) sampled in a subtropical climate (Bahia Tortugas and Bahia Asuncin, BCS, Mexico) from 2002 to 2004. We found that the fatty acid signatures of the red and brown algae were quite stable among seasons and years, in contrast to those of the green algae, which showed a strong annual variation in their fatty acid signature that affected their annual segregation in the factor analysis and are probably a result of net primary production (NPP), which was strongly correlated to individual fatty acids. The fatty acid signature in brown algae is affected by photosynthetically active radiation (PAR), but their variation in the factor analysis is fairly stable despite seasonal or interannual differences. The polyunsaturated fatty acids (PUFAs) were correlated to sea surface temperature (SST) in seagrass. The differences in fatty acid variations between macrophyte groups can provide useful biomarker information for use in trophic analyses.