28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 Measurement Of Fecal Glucocorticoids In Parrotfishes To Assess Stress John W. Turner, Jr.1, Richard S. Nemeth2, Caroline S. Rogers3 1Department of Physiology & Molecular Medicine, Medical College of Ohio 3035 Arlington Avenue, Toledo, Ohio   43614-5804; 2Center for Marine and Environmental Studies, University of the Virgin Islands, Charlotte Amalie, St. Thomas, U.S. Virgin Islands   00802; 3United States Geological Survey, Caribbean Field Station, St. John, U.S. Virgin Islands  00830 Coral reefs are in decline worldwide from a combination of natural and human forces.  The environmental compromises faced by coral reef habitats and their associated fishes are potentially stressful, and in this study we examined the potential for assessing stress levels in coral reef fishes.  We determined the feasibility of using fecal casts from parrotfishes for remote assessment of stress-related hormones (cortisol and corticosterone), and the response of these hormones to the stress of restraint and hypoxia.  Measurement of these hormones in fecal extracts by high performance liquid chromatography (HPLC) was validated using mass spectrometry, chemical derivitization and radioactive tracer methods.  In sixaquarium-adapted parrotfishes, baseline levels of cortisol and corticosterone averaged 3.4 ± 1.1 and 14.8 ± 2.8 ng/g feces, respectively, across 32 days.  During 13 days of periodic stress these hormones respectively averaged 10.8-fold and 3.2-fold greater than baseline, with a return to near baseline during a 23-day follow-up.  Testosterone was also measured as a reference hormone, which is not part of the stress-response axis.  Levels of this hormone were similar across the study.  These fecal hormones were also measured in a field study of parrotfishes in ten fringing coral reef areas around the Caribbean Island of St. John, U.S. Virgin Islands.  Extracts of remotely collected fecal casts of three parrotfish species revealed no difference in respective average hormone levels among these species.  Also, there was no difference in respective hormone levels between aquarium and field environments.  However, levels of both cortisol and corticosterone, but not testosterone, were elevated in two of the ten reef sites surveyed.  This study demonstrated that parrotfish fecals can be collected in aquarium and field conditions and that steroid hormones in these fecals can be extracted and reliably measured.  The study also demonstrates that cortisol and corticosterone in parrotfish fecals can be used as an indicator of the stress response, which is unlikely to be masked by intrinsic variability in the sample source, environment or methodology. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page