Influence of lipid separation on the trophic interpretation of fatty acids

Production, Transport, Fate and Effects of Lipids in the Marine Environment

Lipids form energy storage depots, cellular barriers and signaling molecules. They are generated and metabolized by enzymes under the influence of biotic and abiotic factors, and some-the long-chain polyunsaturated ω3 and ω6 fatty acids and cholesterol-are essential for optimal health in marine organisms. In addition, lipids have direct and indirect roles in the control of buoyancy in marine fauna ranging from copepods to whales. Phytoplankton account for about half of the planet's carbon fixation, and about half of that carbon goes into lipids. Lipids are an important component of the ocean's ability to sequester carbon away from the atmosphere through sinking and especially after transfer to zooplankton. Phytoplankton are the main suppliers of ω3 polyunsaturated fatty acids (PUFAs) in the marine environment. They also supply cholesterol and many phytosterols to ocean ecosystems; however, genomics is indicating that members of the Cnidaria, Rotifera, Annelida, and Mollusca phyla also have the endogenous capacity for the de novo synthesis of ω3 PUFAs as well as phytosterols. It has been predicted that ω3 long-chain PUFAs will decrease in marine organisms with climate change, with implications for human consumption and for carbon sequestration; however, the responses of ω3 PUFA supply to future conditions are likely to be quite diverse.

Fatty acid ratio analysis identifies changes in competent meroplanktonic larvae sampled over different supply events

Planktonic communities are a cornerstone of ocean food webs. Early benthic performance of meroplanktonic organisms is shaped by their life stages in planktonic communities. Fatty acid profiles of marine invertebrates are a good indicator of their nutritional state and allow inferring how dietary regimes experienced during larval pelagic life may drive their pre- and post-metamorphosis performance. Fatty acid profiles of Carcinus maenas megalopae were analysed during four larval supply events in two consecutive years to better understand the variability in their nutritional state at settlement. The logratio analysis of fatty acids showed differences between the four larval supply events, with five ratios explaining 83.1% of the variance. The ratios that contributed to separate larval supply events presented a combination of essential, de novo synthetized and diet origin fatty acids (e.g., phytanate/20:4 n-6, 16:0/18:2 n-4). The high fatty acid signature dispersion found within the same supply event suggests that larvae settling at Ria de Aveiro (Portugal) developed through different planktonic feeding zones and experienced contrasting feeding regimes. The fatty acid profile of megalopae demonstrated a high contribution of diatoms, flagellates and bacteria in the larval diet of C. maenas. The present study demonstrated differences between supply events, although a high variability of larval phenotypes was recorded within the same supply event.