Combined effects of temperature and hypoxia shape female brooding behaviors and the early ontogeny of the Chilean kelp crab Taliepus dentatus

Abstract

The ecophysiology of marine ectotherms is regulated by the interaction of temperature with environmental drivers, such as dissolved oxygen (DO). The combination of low levels of DO and temperature in the ocean affects physiological and behavioral responses, especially in early life history traits of marine species. Here, we aimed to investigate the combined effect of ecologically relevant values of temperature and DO on female brooding behavior as well as on the early ontogeny of the Chilean kelp crab Taliepus dentatus. In a laboratory experiment, after acclimation and mating of females and males in constant temperatures (11 or 14°C), we exposed brooding females to 1 of 2 temperatures (11 or 14°C) and 1 of 2 DO levels (normoxia or cycling hypoxia). We tested the effects of these 4 treatments on embryo and larval sizes, embryo developmental time, female brooding behavior (i.e. embryo ventilation), larval hatching (i.e. number of hatched larvae), Zoea 1 survival to starvation, and swimming speed. We found a negative effect of temperature on the size of early embryos, but no interactions were detected in embryo size during development. High temperature and low DO increased female brooding behavior and larval size, reduced the number of hatched larvae, and affected larval swimming speed. Embryo development time and larval survival were negatively affected by temperature. These results suggest that an increasing frequency of hypoxic events, combined with ocean warming, might have important consequences on marine invertebrate brooders, affecting female fecundity, larval performance and, potentially, their dispersal ability even well within their optimal thermal range.