Ocean Acidification can Mediate Biodiversity Shifts by changing Biogenic Habitat

by Elizabeth Rodarte

Ocean acidification is the process in which the pH of the world’s oceans decreases due to the production of atmospheric CO2. The increase of CO2 and decrease in pH leads to changes in calcification, growth, and abundance of species such as coral reefs, mussels, seagrass, and macroalgae. Habitats experience the indirect effects of such CO2 increases. They must remain resistant to sudden changes in pH and CO2 in order to benefit the organisms they support. By modeling the effects of lowering pH in habitats with corals, mussels, seagrass, and microalgae, we can determine the costs to these species. Coral reefs and mussels are calcifying organisms that are negatively affected by the pH which limits survival and stunts, or even stops, growth and development. Lower pH decreases the species complexity of corals and mussels and ultimately the species richness in habitats. Mytilus mussels, for example, require specific pH to function. The species of mussels, other than Mytilus, that survive decreases in pH lack “structural complexity” to support dense surrounding vegetation. Therefore, the loss of Mytilus mussels due to ocean acidification allows for a more stable yet less diverse habitat. Continue reading

Marine Mollusc Anti-predator Escape Behavior Impaired with Future Ocean Acidification

by Jennifer Fields

Ocean acidification is known to have significant impacts on marine invertebrates in terms of calcification and reproduction; however, the effects of increased CO2 on marine invertebrate behavior are largely unknown. Watson et al. (2014) predicted marine conch snail predator-escape behavior to its predator cone shell would be impaired with near-future CO2 levels. The authors found that the decision-making of the conch snail was in fact impaired by ocean acidification, leaving the snails more vulnerable to predation. The change in behavior was fully restored by treatment with gabazine, suggesting that changes in acid-base regulation caused by increased CO2 in the ocean interfere with the invertebrate’s neurotransmitter receptor function. These alterations in behavior in marine invertebrates could have wide-ranging implications for the whole entire marine ecosystem. Continue reading

Elevated CO2 Affects Tropical Marine Fish Predator-Prey Interactions

by Jennifer Fields

Recent research has demonstrated that exposure to elevated CO2 affects how fish observe their environment, affecting behavioral and cognitive processes leading to increased prey mortality. However, it is unknown if increased prey mortality is caused by changes in kinematics of predator-prey interactions or from just increasing prey activity levels. Allan et al. (2013) studied the effect of anticipated end of this century CO2 concentrations on the predatory-prey interaction of two tropical marine fish. Both a predator and prey fish was exposed to present day and elevated CO2 levels in a cross-factored design. The authors investigated the changes in locomotion performance, prey reaction distance, and capture success of the interaction. Authors found that predators Continue reading