Endocrine responses to diverse stressors of capture, entanglement and stranding in leatherback turtles (Dermochelys coriacea)

Abstract

Limited data on stress physiology exist for leatherback turtles. Examination of 32 leatherback turtles showed that individuals exposed to entanglement, stranding, or entrapment in a weir net had elevated corticosterone and thyroxine compared to healthy controls.

Ameliorating transport-related stress in endangered Kemp’s ridley sea turtles (Lepidochelys kempii) with a recovery period in saltwater pools

“…Before transport, no turtles had corticosterone >10 ng/ml; immediately after transport, all but one turtle had corticosterone >10 ng/ml, with five samples >20 ng/ml. Generally, the amplitude of this increase was similar to that seen after 26 h transport (from 2 to 12 ng/ml) in our earlier study of juvenile Kemp’s ridley turtles (Hunt et al , 2012) and is greater than the minor, typically 2-fold, increase that is attributable to repeated handling and sampling in the absence of transport (Hunt et al , 2016b). Other comparison points from sea turtle stress literature include 3- to 4-fold increases in corticosterone after single stressors such as 2d of osmotic stress, brief turning stress (turtle placed on its back), capture, or stranding (Kemp’s ridley turtles, Ortiz et al , 2000; Gregory and Schmid, 2001; green turtles, Aguirre et al , 1995; leatherback turtles, Dermochelys coriacea , Hunt et al , 2016b).…”

Characterizing the Duration and Severity of Fishing Gear Entanglement on a North Atlantic Right Whale (Eubalaena glacialis) Using Stable Isotopes, Steroid and Thyroid Hormones in Baleen

“…However, different patterns in thyroid output have been reported for some stressors that increase energetic output (e.g., exercise stress), contrary to what is seen during simple fasting (Uribe et al, 2014;Hunt et al, 2016b). For example, entangled distressed leatherback sea turtles had higher serum T 4 than healthy wild individuals, presumably from the added energetic cost of carrying gear (Hunt et al, 2016b). Eg2301 would have likely expended additional energy for locomotion to compensate for the drag associated with the entangling gear (van der Hoop et al, 2013(van der Hoop et al, , 2015(van der Hoop et al, , 2016, which could be an example of exercise stress promoting thyroid function.…”

“…The thyroid panel of Eg2301 during the entanglement period is also surprising because stress is generally thought to inhibit thyroid secretions (Eales, 1988;Norris, 2006). However, different patterns in thyroid output have been reported for some stressors that increase energetic output (e.g., exercise stress), contrary to what is seen during simple fasting (Uribe et al, 2014;Hunt et al, 2016b). For example, entangled distressed leatherback sea turtles had higher serum T 4 than healthy wild individuals, presumably from the added energetic cost of carrying gear (Hunt et al, 2016b).…”

The Utility of Combining Stable Isotope and Hormone Analyses for Marine Megafauna Research

“…GC concentrations have been analyzed in numerous marine mammal and turtle species ranging from individual responses to stressors like restraint or capture of individual animals (Thomson and Geraci, 1986;Geraci, 1988, 1989;Gregory et al, 1996;Champagne et al, 2012;St. Aubin et al, 2013;Williard et al, 2015;Hunt et al, 2016a), to population-level responses to increased anthropogenic activity (e.g., vessel traffic; Ayres et al, 2012;Rolland et al, 2012). Glucocorticoid concentrations also vary with temperature perturbations (Houser et al, 2011), nutritional deficits (Kellar et al, 2015;Beaulieu-McCoy et al, 2017;Wasser et al, 2017), and pollutant exposure (most notably oiling from the Deepwater Horizon disaster; Schwacke et al, 2014).…”