Climate change: what will it do to fish–parasite interactions?

Climate change‐related factors are predicted to affect aquatic environments in many ways. Fish physiology, immunology, behaviour, and parasite‐avoidance strategies are likely to be affected by climate change and this may lead to ecosystem‐level changes. Parasitic organisms that exploit fish are also likely to be affected by climate change, both directly and via climate effects on their hosts. It is possible that climate change will alter the prerequisites for parasite transfer, for example, through changes in phenological relationships, and/or change the direction and pressure of selection in host–parasite relationships. Our review indicates strong multifactorial effects of climate change on fish–parasite systems. Increased water temperature is, on the one hand, predicted to enhance parasite metabolism, resulting in more rapid spread of parasites; on the other hand, the occurrence of some parasites could also decrease if the optimal temperature for growth and transmission is exceeded.