Effects of Parasites on Fish Behaviour: Interactions With Host Physiology

There is an increased interest from fisheries biologists, aquaculturists, evolutionary, and behavioural ecologists in the behavioural changes in fish hosts that are associated with parasite infections. This Chapter introduced the various ways in which parasites may influence the behaviour of teleost fishes, focusing particularly on behavioural changes that are induced by parasites following infection. We systematically reviewed each of the major physiological systems of fish (e.g., ionic balance, neurochemistry, endocrine function, and nutritional status), the effects of parasites on them, and examined how infection-associated changes in functioning may impact on normal patterns of host behaviour. There are few host-parasite systems for which physiological and behavioural effects of infection have been quantified experimentally, but where possible those studies for which both types of data are available were reviewed. Major gaps in knowledge were also highlighted for further research. This Chapter ended by emphasising the value of a mechanistic approach for understanding the evolution and likely fitness consequences of infection-associated host behaviour modification, and highlighting opportunities to exploit postgenomic technologies to further elucidate the physiological basis of infection-associated changes in host behaviour.