Effects of temperature on reproductive timing and hatching success in a tropical fiddler crab

The timing of reproduction is critical to reproductive success in many animal species. Parents that can perceive and respond to environmental cues and time the hatching/birth of their offspring to optimal environmental conditions show higher reproductive success. Intertidal ectotherms are under particularly strong selection because larval development rates are temperature-dependent, and larvae must hatch during the highest spring tides to avoid high levels of inshore predation. Here we investigate whether female fiddler crabs, Austruca mjoebergi, can mitigate the effects of high temperatures by adjusting the timing of reproductive events and/or by behavioural compensation. We experimentally manipulated incubation temperatures between 30 and 36 °C, based on natural and predicted temperature conditions, and found that hatching success decreased linearly with increasing temperatures. However, temperature had no effect on the timing of fertilization or hatching, suggesting that larval development rate was not temperature-dependent. Across the tested temperatures, females did not adjust egg size, the amount of yolk in each egg, larvae size or clutch size. In conclusion, high temperatures prevented clutches from reaching the hatching stage, but within the range of temperatures that facilitated hatching, there was no evidence of behavioural compensation and no discernible effect of temperature on reproductive timing.