High pCO2 and elevated temperature reduce survival and alter development in early life stages of the tropical sea hare Stylocheilus striatus

Elevated temperature (ocean warming) and reduced oceanic pH (ocean acidification) are products of increased atmospheric pCO(2), and have been shown in many marine taxa to alter morphology, impede development, and reduce fitness. Here, we investigated the effects of high pCO(2) and elevated temperature on developmental rate, hatching success, and veliger morphology of embryos of the tropical sea hare, Stylocheilus striatus. Exposure to high pCO(2) resulted in significant developmental delays, postponing hatching by nearly 24 h, whereas exposure to elevated temperature (in isolation or in combination with high pCO(2)) resulted in accelerated development, with larvae reaching several developmental stages approximately 48 h in advance of controls. Hatching success was reduced by similar to 20 and 55% under high pCO(2) and warming, respectively, while simultaneous exposure to both conditions resulted in a nearly additive 70% reduction in hatching. In addition to these ontological and lethal effects, exposure of embryos to climate change stressors resulted in significant morphological effects. Larval shells were nearly 40% smaller under high pCO(2) and warming in isolation and up to 53% smaller under multi-stressor conditions. In general, elevated temperature had the largest impact on development, with temperature-effects nearly 3.5-times the magnitude of high pCO(2)-effects. These results indicate that oceanic conditions congruent with climate change predictions for the end of the twenty-first century suppress successful development in S. striatus embryos, potentially reducing their viability as pelagic larvae.