Meeting Abstract

P2-96   -   Longer day length may maximize larval growth in captive Devils Hole pupfish but are there physiological costs? Gumm, JM*; Feuerbacher, OG; Irwin, K; Gabor, CR; US Fish and Wildlife Service; US Fish and Wildlife Service; Texas State University; Texas State University jennifer_gumm@fws.gov

Artificial light at night (ALAN) is a form of anthropogenic pollution that alters the natural light and dark cycle in an ecosystem. ALAN can affect circadian and circannual rhythms, physiology and behavior. ALAN affects the photoperiod across life history stages, including reproduction, growth, development, and activity in aquatic organisms. Many qualities of light availability may influence fish in captivity as well and should be considered in the context of aquaculture methods. Photoperiod or daylength and light intensity are the most well-studied aspects of light availability in the context of aquaculture. Of particular interest is the feeding response of larval fish in response to different light conditions. In many species, longer daylengths interact with food availability to maximize growth, however, the response to ALAN on fish physiology including the endocrine stress response, is often unknown. Here, we test the response of endangered Devils Hole pupfish (Cyprinodon diabolis) to ALAN, by measuring cortisol release rates, as well as testing response to an acute stressor. We used non-invasive water-borne hormone methods to measure cortisol release rates before and two weeks after moving fish out of ALAN exposure. Cortisol release rates over an hour were very high so in the future we can test fish over 30 min. We found that there was no significant difference in cortisol production after a change in ALAN, suggesting that the benefit of maximizing growth may not come at a physiological cost. Fish also showed a significant increase in cortisol release rates to an acute stressor, indicating that captive Devils Hole pupfish have a healthy HPI axis. Future studies examining the role of hormones in reproduction, growth and development can now be pursued in this small, endangered fish using this non-invasive method.