Effects of Ocean Acidification and Warming on the Physiology of Crassostrea virginica Larvae: From the Cellular to Whole-organism Levels

Due to natural and anthropogenic influences, estuaries experience highly variable environmental conditions both spatially and temporally, and water conditions regularly reach projected 2100 IPCC open ocean average values. Multiple dynamic environmental parameters of estuaries can affect larval oysters through changes in overall growth and metabolic performance. For example, different temperature regimes during larval development can challenge energy requirements for maintaining homeostasis, causing metabolic rates to shift beyond optimum ranges. Furthermore, shifts in metabolism can increase cellular stress with the production of reactive oxygen species, termed oxidative stress. Temperature is not the only environmental parameter that oyster larvae experience; carbonate chemistry parameters can also fluctuate, affecting important physiological processes. While temperature and carbonate chemistry can independently affect homeostasis, it is important to consider the interaction of these two environmental parameters during larval development. Few studies on oyster larvae have examined effects of multiple stressors and the underlying physiological mechanisms, like changes in metabolic rate or levels of stress response molecules, making physiological effects from multiple stressors an important area to study. We cultured oyster larvae from fertilization to 11 days post fertilization under a factorial combination of two temperature and carbonate chemistry scenarios, referred to in terms of pH: control temperature and pH, low pH, high temperature, and a multi-stressor treatment. To detect physiological mechanisms of organismal stress from the cellular to whole-organism levels, we measured antioxidant defense, total protein, total lipid, rates of oxygen consumption, and growth. Understanding the impacts of multiple stressors at both the cellular and whole-organism levels help identify sub-lethal effects that could hinder the success of oyster populations in the future.