Correlations between environmental salinity levels, blood biochemistry parameters, and steroid hormones in wild juvenile American alligators (Alligator mississippiensis)

• Published in: Scientific reports Vol. 11; no. 1; pp. 15168 - 13
• Main Authors: Faulkner, Patricia C., Elsey, Ruth M., Hala, David, Petersen, Lene H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.07.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 631/443; 692/163; 704/172; Aldosterone; Alligator mississippiensis; Alligators; Alligators and Crocodiles - blood; Androgens; Angiotensin; Animals; Animals, Wild; Anthropogenic factors; Aquatic animals; Aquatic habitats; Aquatic reptiles; Biochemistry; Climate Change; Drought; Ecosystem; Electrolytes; Electrolytes - blood; Estrogens; Female; Fresh Water - chemistry; Freshwater environments; Glucocorticoids; Glucocorticoids - blood; Gonadal Steroid Hormones - blood; Hormones; Hormones - blood; Humanities and Social Sciences; Liquid chromatography; Louisiana; Male; Males; Mass spectrometry; Mass spectroscopy; multidisciplinary; Renin; Renin-Angiotensin System; Salinity; Salinity effects; Salinization; Science; Science (multidisciplinary); Sea level rise; Seasonal variations; Seasons; Steroid hormones; Steroids; Storm surges; Tidal waves; Wetlands; Wildlife; Wildlife conservation; Wildlife refuges; Louisiana
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-94557-y

American alligators ( Alligator mississippiensis ) inhabit freshwater wetlands that are vulnerable to salinization caused by anthropogenic alterations to freshwater flow, in addition to storm surges, sea level rise, and droughts. Salinization of coastal freshwater habitats is a growing concern in a changing climate due to increased frequency and intensity of storm surges and drought conditions. This study opportunistically sampled juvenile male and female wild alligators in various salinities each month excluding November, December, and January for one year at Rockefeller Wildlife Refuge in coastal Louisiana. Blood plasma biochemistry parameters including electrolyte levels were subsequently measured. In addition, levels of various renin–angiotensin–aldosterone system hormones, glucocorticoids, androgens, estrogens, and progestogens were analyzed using liquid chromatography and tandem mass spectrometry. Only males were sampled in hyperosmotic environments (> 10‰) during dry conditions in late summer 2018. In juvenile males, plasma Na + , Cl − , and the progestogen 17α,20β-dihydroxypregnenone were significantly and positively correlated with environmental salinity. However, variation in glucocorticoids, androgens, and estrogens were not associated with hypersaline water while sex steroids showed significant seasonal variation. This study demonstrated significant correlation of environmental salinity with electrolyte levels and a sex steroid in wild juvenile alligators, and to our knowledge represents the first measurement of 17α,20β-dihydroxypregnenone in alligators.