Effects of CO2-driven ocean acidification on the early developmental stages of invertebrates

CO2 emissions arising from the burning of fossil fuels have altered seawater chemistry far more rapidly than the Earth has previously experienced, and the rate and extent of this change are expected to affect shallow water marine organisms. The increased CO2 diffuses from the atmosphere into ocean surface waters, resulting in increased partial pressure of CO2, and reduced [CO32-] and pH. The CO2-driven ocean acidification leads to a decrease in calcium carbonate (CaCO3) saturation state in the ocean surface waters and has potential impacts on calcifiers. The present study focuses on the effects of ocean acidification on early developmental and reproductive stages of calcifiers, both of which are believed to be the most vulnerable stages to environmental change within a life cycle. Laboratory experiments revealed that ocean acidification has negative impacts on the fertilization, cleavage, larva, settlement and reproductive stages of several marine calcifiers, including echinoderm, bivalve, coral and crustacean species. There appear to be significant ontogenetic impacts and species-specific differences in tolerance to the high CO2 levels. The conclusion is that future changes in ocean acidity will potentially impact the population size and dynamics, as well as the community structure of calcifiers, and will therefore have negative impacts on marine ecosystems. Further studies are needed to evaluate the potential impacts on non-calcifiers, as well as the synergistic impacts of ocean acidification and climate change. Studies should also focus on the adaptive capability of marine organisms, which will be crucial to the ability to forecast how marine organisms and ecosystems will respond to the world's oceans as they warm and acidify.