Meeting Abstract
9.4 Friday, Jan. 4 Tolerance of early life history stages of Australian intertidal sea stars to ocean warming and ocean acidification: sensitivity of lecithotrophic developers NGUYEN, H.D.*; DOO, S.S.; SOARS, N.A.; THOMSON, M; BYRNE, M; University of Sydney; University of Sydney; University of Sydney; University of Sydney; University of Sydney hong@anatomy.usyd.edu.au
Anthropogenic ocean warming and acidification is potentially detrimental to the sensitive early life stages of benthic marine invertebrates. Most studies have focused on the effects of ocean acidification as a single stressor on calcifying planktotrophic larvae with a paucity of data on species with alternate non-calcifying developmental strategies, the early juvenile stage and, on the interactive effects of warming and acidification. To address these knowledge gaps, the development of the non-calcifying lecithotrophic larvae of the sea star Meridiastra calcar and the lecithotrophic juvenile of the sea star Parvulastra exigua were investigated in the setting of predicted ocean warming (+2-4°C) and acidification (-0.4-1.0 pH units) for 2100 and beyond. For M. calcar, pH had a greater negative effect on embryos reaching the hatched gastrula stage than larvae. Mortality and abnormal development in larvae increased significantly even with a +2°C warming and, larval growth was impaired at +4°C. Negative effects on P. exigua juveniles occurred only at -1.0 units pH units where there was an increase in mortality and abnormal development. There were no interactive effects of temperature and pH across all stages monitored for either species. For M. calcar, warming not acidification was the dominant stressor. In contrast, juvenile P. exigua were resilient to projected near future ocean (ca. 2100) acidification and warming. Heat shock protein expression 70 kDa (hsp70) in the embryos and adults of M. calcar indicated that the developmental stages do not elevate expression of this protein in response to thermal spikes, but the adults do as a potential defensive strategy to warming in their tide pool habitat.
