Abstract
The Atlantic Goliath Grouper (Epinephelus itajara) population has rebounded from near extinction to an international status as vulnerable due in part to regional species recovery efforts. The southeastern US population has been recovering with the main spawning locations off the coasts of Florida. Despite their economic importance to the catch-and-release fishery and the dive industry, and their ecological importance as ecosystem engineers resulting in positive impacts on reefs and species richness, baseline health assessment information is very limited in this species to date. The objectives of this study were to: (1) establish reference intervals for hematological and plasma biochemical analytes, and report immune function, oxidative stress, and vitellogenin in mature males and females; (2) evaluate total length, age, and sex in relation to blood analytes in juvenile and mature fish; (3) assess analytes across sampled months in mature male and female fish; and (4) describe the typical light microscopy findings in liver and gill biopsies, including quantitative assessment of pigmented macrophage aggregates. Health indices are reported as reference intervals when applicable, or otherwise descriptively. Blood analyte correlations with length and age, sex differences, and comparisons across months provided relevant physiological considerations, including differences in protein/energy metabolism, tissue growth, sexual maturation, active reproduction, and antigenic stimulation. Liver histology identified changes associated with life stage, active reproduction, or of subclinically to clinically insignificant infectious and/or inflammatory processes. Hepatocellular vacuolation and pigmented macrophage aggregates were prominent. Pigmented macrophage aggregates correlated with total length, presumably from continuous antigenic stimulation and/or metabolic changes as fish grow. Gill histological findings were subtle. The data presented herein provide an essential baseline assessment of a suite of health variables in an iconic marine teleost species, serves as a springboard for future studies relevant to conservation physiology, and allows for population-level applications for conservation management and policy.
Highlights
Conservation physiology is a newly emerging discipline that examines the health status and physiological responses of wildlife to environmental disturbances in an effort to better understand factors contributing to population declines [1, 2]
These assessments are crucial for conservation efforts, as wildlife are increasingly faced with such anthropogenic threats as climate change, habitat loss, pathogen introduction, contaminant exposure, and overexploitation [3,4,5]
This research was performed in accordance with institutional and national guidelines concerning the use of animals in research, and was approved by the Florida State University Institutional Animal Care and Use Committee (IACUC); Florida Fish and Wildlife Conservation
Summary
Conservation physiology is a newly emerging discipline that examines the health status and physiological responses of wildlife to environmental disturbances in an effort to better understand factors contributing to population declines [1, 2] These assessments are crucial for conservation efforts, as wildlife are increasingly faced with such anthropogenic threats as climate change, habitat loss, pathogen introduction, contaminant exposure, and overexploitation [3,4,5]. Population-level health assessments involve a combination of physical and physiological examinations in an effort to establish “baselines” for hematological and biochemical analytes [2,3,4] It is when shifts in these biomarkers occur that physiologically relevant alterations in population health in response to various stressors can be recognized [6, 7]. Population health and viability are inseparable, and monitoring the health of organisms and their populations can be used to inform management and to improve upon our understanding of complex conservation issues [2, 3]
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