Maternal investment of kelp crabs from central Chile is associated with the level of environmental fluctuations and predictability

Environmental fluctuation dictates life cycles in many ecosystems on earth, especially within marine coastal areas. The magnitude of those fluctuations at ecologically relevant time scales (i.e. hours and days) induces phenotypical adjustment in aquatic organisms, including maternal investment in offspring. However, the effect of the magnitude and the periodicity of those fluctuations on animal physiology has been poorly investigated. In this study, we investigated the correlation between environmental fluctuation and maternal investment in offspring. We focused on one population of the kelp crab Taliepus dentatus from central Chile and considered whether fluctuations in water temperature, dissolved oxygen and salinity are associated with temporal changes in maternal investment in early embryos (volume, lipid content and fatty acid composition) over a period of 1 yr. We used remote data loggers deployed at an ecologically relevant temporal scale to calculate the monthly magnitude, periodicity and predictability of environmental fluctuations. We found substantial variation among females in embryo volume, lipid content and fatty acid composition during the year, mostly associated with seasonality (average environmental conditions). However, embryo lipid content and essential fatty acids (arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid) showed a clear negative relation with the monthly predictability of the environmental fluctuations. This study shows how the integration of environmental fluctuations and their predictability can improve our understanding of the reproductive ecology of marine coastal species.