Meeting Abstract
S9-1.4 Monday, Jan. 7 Impacts of warming and ocean acidification on growth of larval and juvenile sea urchins – from the poles to the tropics BYRNE, M; Univ. of Sydney, Australia mbyrne@anatomy.usyd.edu.au
The Temperature Size Rule states that temperature increases development rates of ectotherms faster than growth rates, resulting in smaller body sizes at life history transitions. Thus a decline in body size is predicted to be a response to global warming. Ocean acidification reduces body size in marine ectotherms as growth rates decrease with reduced carbonate availability and physiological hypercapnia. Ocean warming and acidification covary, but it is not known how they will interact to affect development, growth, size at maturity and other proxies of fitness. To address these issues, the response of sea urchin life histories from across world latitudes to warming and acidification was investigated. Exposure to stress early in development can have negative downstream effects because performance of later ontogeny depends on success of early stages. Embryos generated on ocean change conditions are sensitive to warming and may not reach the calcifying stage in the absence of parental acclimation and adaptation. Larvae are sensitive to warming and acidification. The effects of acidification in echinoplutei indicate that the stunting effect of pH/pCO2 is influenced by physiological hypercapnia and teratogenic effects. In long-term rearing of juveniles to maturation acidification reduced body size and warming mitigated this effect. Sea urchins were larger at maturity under projected warming and acidification scenarios suggesting that body size will not necessarily decrease with climate change. Reproductive potential showed a negative response to acidification with varying levels of mitigation by warming. It may be too early to make firm predictions on the effect of marine climate change on body size. The data highlight the need to examine how covarying stressors interact in long term studies.
