Atlantic Cod Avoid Both CO2 and Predator Odor After Long-term Exposure to Elevated CO2

by Jennifer Fields

Many recent studies have suggested that the behavior of teleost coral reef fish will be highly affected by ocean acidification. While elevated CO2 reduces predator avoidance in coral reef fish, it is still unknown if elevated CO2 has the same effects on teleosts in other parts of the world. Teleosts have unique receptors that detect ambient CO2 concentrations, and therefore they might be able to avoid areas of high CO2. Jutfelt and Hedgärde (2013) investigated how long-term exposure to end of century CO2 concentrations affects CO2 avoidance and predator avoidance in juvenile teleost Atlantic cod. After six weeks of exposure to elevated CO2, fish were put in a flume and given a choice between conditions of control seawater and no predator cue versus elevated-CO2 water with predator cue. Despite the long-term exposure to elevated CO2, the cod avoided the smell of the predator, suggesting that cod may be tolerant to elevated CO2. Both treatment groups had a strong avoidance to water with high CO2, suggesting that fish similar to Atlantic cod may alter their movements and migrations in search of water with lower CO2 levels. 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

Behavior Alterations in Temperate Fish with Elevated-CO2

by Jennifer Fields

Anthropogenic CO2 emissions are causing an increase in dissolution of CO2 into the oceans resulting in ocean acidification. Teleost fish have been thought to have a high tolerance to ocean acidification because their specialized gills allow them to regulate the pH of their blood. However, recent studies have reported strong behavioral effects of ocean acidification in tropical coral reef species. The studies found that there was a diminishment of risk-assessment, learning, lateralization, and prey detection with increased dissolved CO2. But, little is known about the behavioral changes of temperate fish under the same conditions. Jutfelt et al. (2013) observed behavioral disturbances in boldness, exploratory behavior, lateralization, and learning in temperate fish under end of century ocean acidification conditions. The findings suggest that behavioral changes from increased CO2 are not limited to sensitive tropical species and could affect fish on a global scale by the end of the century. Continue reading