Warmwater animal species—including freshwater fish, snails, mussels, and crayfish—can be loosely defined as those that prefer fairly high temperatures. Warmwater fish for example, have temperature preferences above about 77 degrees. Still, there are upper limits to the temperatures even warmwater species can live with, beyond which physiological processes break down and susceptibility to disease increases.
Climate models predict that summer and winter temperatures will increase across the United States in the coming decades. These higher temperatures as well as changes in availability of water due to drought are predicted to affect warmwater species directly.
Although warmwater species are not generally expected to face the nearly universal declines predicted for coldwater fishes, many could actually face local and even global extinction as temperatures increase and other non-native species invade their habitats. Habitat loss for warmwater species is predicted to be greatest in the southern United States, an area with some of the most species-rich rivers and streams in the world.
Warmwater species may respond to climate change in a variety of ways. The possibilities include adaptation, migration, use of local refuges, and changes in behavior. Its difficult to predict how they will react without more scientific knowledge about individual species and the interactions among species, including those new to the community.
SRS fisheries research scientist Susie Adams recently wrote a synthesis about warmwater species for the Forest Service Climate Change Resource Center. She includes an overview of the issues and the present state of warmwater species across the United States, concluding with seven options for managers concerned with increasing resiliency in these species.
Read the synthesis here: http://www.fs.fed.us/ccrc/topics/aquatic-ecosystems/warmwater-aquatic-fauna.shtml