The Effect of Increasing Acidity on Stage Z1 Blue Crabs, Callinectes sapidus

As carbon dioxide concentrations continue to increase and the ocean absorbs increasing quantities of CO₂, one serious result is declining ocean pH. In regions of upwelling and coastal zones affected by terrestrial inputs, this is especially consequential to organisms sensitive to heightened acidity. Crustaceans in the Pacific Northwest experience increased mortality when exposed to conditions of lower pH in the earliest life stages (Long et al. 2013). Similarly, a study in the Gulf of Mexico on the Atlantic blue crab suggests higher mortality in addition to changes in morphology (Giltz & Taylor, 2017). This present study evaluates the effect of diminished pH on stage zoea I Atlantic blue crabs (Callinectes sapidus) from the Chesapeake Bay. Zoea were exposed acidic conditions of pH 6.8, 7.4, and 8.1 for seven days. Increased mortality was found at pH 6.8 (p<0.005) while a mixed but still significant decline in survival was observed for pH 7.4 (p=0.018). Total length, carapace length, rostral length, and dorsal length measurements were collected from all specimens, with significant differences observed in carapace and dorsal length at pH 6.8 (p=0.002 and p<0.005, respectively). At pH 7.4, carapace length differed by 5.5% and rostral length by 14% from pH 8.1. Total lipid concentration significantly differed at pH 6.8 (p<0.005) whereas no significant difference was found for total protein concentration at pH 6.8 or for total lipid and total protein concentration at pH 7.4 (p=0.0504, p=0.477, and p=0.457, respectively). Continuing studies include carapace content and evaluating the combined effect of temperature and pH on mortality and morphology.