How do early life stage Atlantic blue crabs (Callinectes sapidus) respond to changes in acidity and the interaction between acidity and temperature?

Abstract:

As nations and governmental bodies continue to discuss rising carbon dioxide concentrations, the ocean has accumulated approximately a third of global output and correspondingly is becoming more acidic. One commercially valuable species in the Eastern United States, the Atlantic blue crab (Callinectes sapidus), experiences increased mortality at higher acidities in their first zoeal stage. However, there has been no information produced on their developmental progression at the embryonic stage, nor has there been any data on zoeal responses to the combined stressors of temperature and acidity. Through my research, I found that embryonic development and hatching day is delayed at lower pH (pH 6.8), with no significant impacts observed at a moderately lower pH (pH 7.4) compared to standard ocean pH (pH 8.1). Stage 1 zoea mortality was negatively affected when temperature alone was increased (26 and 28 C from 23 C); the effects were exacerbated when exposed to increased acidity as well (pH 7.4 and 7.8). Total lipid and protein content was also analyzed in stage 1 zoea. Total protein was significantly affected by heightened temperature alone and pH alone, whereas total lipid content was unaffected. Swimming activity was significantly affected with increased acidity alone and combined temperature and acidity changes. Although embryos were exposed to quite low pH conditions, the Chesapeake Bay currently can experience similar periodic extremes and are expected to worsen over the next century. Stage 1 zoea, developing in surface currents on the coastal shelf, are expected to be exposed to the experimental conditions over the next century as well, highlighting the likelihood of reduced population level survivals, with corresponding reductions in recruitment rates. Owing to localized dependence on blue crab harvests, reduced populations are expected to impact human populations throughout the Chesapeake Bay.