Abstract
One of the most prevalent changes that aquatic ecosystems face due to climate change is the increase of atmospheric carbon dioxide levels resulting in acidification. This study was aimed at understanding how acidification alters behavioral characteristics and competition of two keystone species of crayfish: virile (Faxonius virilis) which were considered native and rusty (Faxonius rusticus) which were considered non-native. Size matched individuals were dosed in separate tanks with pH ranging from an ambient 8.4 to an acidic 6.4 for 5 days. Both crayfish were then placed into the same flow-through mesocosm, and behaviors were recorded to measure competition over two different food preferences (high and low quality) and two different shelters (high and low quality). Analysis determined a decrease in pH resulted in a change in resource use and a shift in competitive balance between the two species. Results also determined that spatial arrangement of the different resources altered resource use. Specifically, rusty crayfish were seen to favor preferred resources in the preferred-preferred arrangement while virile crayfish were observed to use resources in the preferred-less preferred arrangement. The results in this study show the impact acidic conditions have on competitive behaviors between native and non-native species.