P3.117 Friday, Jan. 6 Effects of ocean acidification on growth, development, and calcification of gastropod embryos: does encapsulation matter? FERNANDES, D.A.O.; PODOLSKY, R.D.*; College of Charleston; College of Charleston email@example.com
Increases in atmospheric CO2 have brought rapid declines in oceanic pH and calcium carbonate saturation levels. Because calcification rate depends on these physical factors, acidification has raised concerns about the future health of calcifying organisms. In addition to altering calcification, low pH can also cause physiological stress and reduce growth. These effects may be especially critical during development, as many organisms lay down protective calcified structures before metamorphosis. Larval shell formation in marine molluscs, for example, is negatively affected by low pH, though such effects have not been studied in encapsulated embryos, where intracapsular fluids might buffer against certain environmental effects. We examined the effects of acidification on growth, development, and larval shell formation in the intertidal mud snail Nassarius obsoletus, which develops in intertidal environments that are expected to be strongly influenced by future pH change. Encapsulated embryos were reared in seawater under atmospheric conditions matching 1x-, 2x-, and 4x–current CO2 concentrations. The inorganic content of hatchlings, largely reflecting shell deposition, declined with increasing pCO2, most dramatically between the 1x and 2x treatments. Organic content, however, was unaffected by the same pH changes, indicating that tissue growth was not similarly inhibited. Hatchling shell length and development rate both declined in parallel with inorganic content. These results suggest that growth and development in encapsulated embryos can be differentially sensitive to acidification. In addition, studies that use shell size as a proxy for growth could underestimate the rate of tissue growth under conditions where calcification is compromised.