Lipid storage patterns in marine copepods: environmental, ecological, and intrinsic drivers

Seasonality of food supply is a major driver of physiological and ecological adaptations of marine zooplankton. High-latitude marine copepods accumulate lipids for maintenance and reproductive maturation during the food-depleted winter period. The relationship between latitude and lipid storage in copepods is well established, but it is influenced by many factors, such as trophic position, sex, and depth distribution. In this study, the influence of latitude and collection depth, trophic level, sex, and the presence or absence of dormancy on the relative amount and composition of lipids stored was assessed by analysing published data. Our analyses confirmed higher lipid contents (expressed as % dry weight) in high-latitude species, and in deep-dwelling tropical copepods compared to shallow-living ones. Contrary to our original hypothesis, carnivorous and herbivorous copepods had similar lipid levels. Copepod species that undergo dormancy had higher levels of wax ester and were more common at polar and temperate latitudes. Lastly, adult male and female copepods did not significantly differ in the amount of lipids they store, suggesting that the portion of male reproductive investment, which may depend on lipid stores, has been underestimated. Taken together, these results both confirm some previously reported trends and refute others.