Stress and fish reproduction: the roles of allostasis and hormesis.
This paper is a review of the effects of stress on reproduction in fishes. I hope to further the development of the concepts of allostasis and hormesis as relevant to understanding reproduction in general and in fish in particular. The main contentions I derive in this review are the following: Stressors affect fish reproduction in a variety of ways depending on the nature and severity of the stressor. The effects are transduced through a hormonal cascade initiated by perception of the stressor and involving the hypothalamus-pituitary-interrenal axis, the catecholamines, and also cytokines. Mounting a stress response and resisting a stressor is an energetically costly process, including costs associated with allostasis, attempting to reset homeostatic norms. Responses in emergency situations (e.g., being chased by a predator or a net) can be different from those where fish can cope (e.g., being in a more crowded environment) with a stressor, but both situations involve energy re-budgeting. Emergency responses happen in concert with the onset of energy limitations (e.g., the fish may not eat), while coping with allostatic overload can happen in a more energy-rich environment (e.g., the fish can continue to eat). Low levels of stress may have a positive effect on reproductive processes while greater stress has negative effects on fish reproduction. The concept of hormesis is a useful way to think about the effect of stressors on fish reproduction since responses can be nonmonotonal, often biphasic.
Schreck
Carl B
CB
Oregon Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, Oregon State University, Corvallis, OR 97331, USA. carl.schreck@oregonstate.edu
D000222:Adaptation, Physiological / Q000502:physiology; D052636:Allostasis / Q000502:physiology*; D000818:Animals; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D005399:Fishes / Q000502:physiology*; D006728:Hormones / Q000378:metabolism / Q000502:physiology; D008297:Male; D012098:Reproduction / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*
D006728:Hormones