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With carbon dioxide levels on the rise, studies to investigate the possible detriment that climate change will have on our ecosystems and the organisms that live within them are essential. The field lacks an abundance of studies focusing on the effects of rising CO2 levels on freshwater organisms. This study looks at the effects of a CO2 gradient on the freshwater crayfish Procambarus clarkii. The gradient allows the crayfish to choose to avoid or prefer the higher carbon dioxide levels. Previous studies have looked at the effect of high CO2 levels, decreased pH, on a variety of crustaceans, but did not use the gradient. Crayfish were introduced into a control environment and observed for normal behavior then introduced into a CO2 gradient environment. The crayfish did not prefer a particular section of the tank in the control environment, making the CO2 gradient experiment possible. When in the CO2 gradient, the crayfish significantly preferred Sections 1, 2, and 3 over Section 4 (where the highest CO2 levels were present). In the CO2 gradient, the crayfish exhibited less hiding behavior and did not acclimatize to the CO2 levels over time. The crayfish left themselves to be more vulnerable to their surroundings. However, exploratory and feeding behavior were surprisingly not affected by the CO2 gradient environment. Rising carbon dioxide levels have the potential to negatively affect freshwater organisms such as the crayfish, but crayfish also may have the potential to adapt to these alterations brought about by climate change, especially if the change takes place over a significantly longer period of time.

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