Meeting Abstract
Increased atmospheric pCO2 is expected to lead to decreased oceanic pH and increased frequency and severity of extreme heat events, both of which are likely to be deleterious for intertidal ectotherms. However, responses to these forcing agents can vary greatly even within a single species, and sensitive early life history stages may pose an ecological weak link in population persistence. We investigated the effects of reduced pH and acute thermal stress on growth and survival of embryos of the porcelain crab Porcellana platycheles. Early stage embryos were removed from field-collected females (n = 6; 96 embryos/female) and reared until hatching (~27 days) under one of two pH treatment conditions (pH=8.0, pH=7.6). Embryos were exposed to one of four temperature regimes: (1) constant ambient 20 °C, or 1 h exposure to 31 °C on (2) Day 1, (3) at start of heart beat, or (4) both Day 1 and start of heart beat. Photos of embryos were taken every other day for the duration of the experiment. Embryo lengths and volumes were estimated from photos using the program ImageJ and growth rates were calculated as change in length/time. Embryo mortality was ~1.5 times higher with heat shock in early development (Day 1) under low pH when compared to controls, suggesting that P. platycheles embryos are likely to be strongly negatively impacted by acute heating events predicted under future climate scenarios. This project was funded by NSF grant MCB-1041225 to JHS, and PU funding to PC.
