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

Abstract

Sea turtle rehabilitation clinics and aquaria frequently transport stranded sea turtles long distances out of water, e.g. for release at sites with appropriate water temperatures. Endangered Kemp's ridley turtles (Lepidochelys kempii) are known to exhibit an adrenal stress response during such transports. In an opportunistic study of turtles transported by road from Massachusetts to Georgia for release, we tested whether placing turtles in saltwater pools for short periods after transport would help turtles recover from transport-related stress. Eighteen juvenile Kemp's ridley turtles were examined and blood samples collected (1) immediately pre-transport, (2) immediately post-transport and (3) after a 6 h (n = 9) or 24 h (n = 9) post-transport period in unfamiliar pools, after which all turtles were released to the sea. Blood samples were analyzed for corticosterone, glucose, total white blood cell (WBC) count, heterophil/lymphocyte (H/L) ratio, pH, pO₂, pCO₂, HCO₃ (bicarbonate), sodium, potassium, ionized calcium, lactate and hematocrit. Though the majority of turtles remained in good clinical condition, corticosterone, glucose, WBC and H/L elevated significantly during transport, while potassium declined slightly but significantly. After at least 6 h in a saltwater pool, potassium and glucose returned to pre-transport baselines and corticosterone partially recovered toward baseline. Extending the pool time to 24 h did not markedly enhance the physiological recovery of turtles, and two immune measures (WBC, H/L) remained elevated from the effect of transport. Six hours in a saltwater pool appears to facilitate the recovery of Kemp's ridley sea turtles from transport-related stress and may therefore improve their readiness for release.

Keywords: Chelonian; corticosterone; glucose; soft release; stress; transportation.

Figure 1

Plasma corticosterone (A), plasma glucose (B), total white blood cell count (C) and heterophil/lymphocyte ratio (D) of 18 juvenile Kemp’s ridley sea turtles transported out-of-water for ~24 h and then placed in saltwater pools for recovery. Symbols indicate data from individual turtles; central bar and whiskers indicates mean ± SEM for normally distributed data (glucose) or median ± interquartile interval for non-normal data (corticosterone, WBC and H/L ratio). ‘After pool recovery’ data includes turtles sampled after 6 h (closed diamonds) or 24 h (open diamonds) in pools. P values for individual variables shown only if multivariate GLMM analysis indicated an overall significant difference in that group of variables; ‘NS’ = no significant difference in the multivariate GLMM

Figure 2

Potassium (A), pO₂ (B) and hematocrit (C) of 18 juvenile Kemp’s ridley sea turtles transported out-of-water for ~24 h and then placed in saltwater pools for recovery. Symbols indicate data from individual turtles; central bar and whiskers indicates mean ± SEM. ‘After pool recovery’ data includes turtles sampled after 6 h (closed diamonds) or 24 h (open diamonds) in pools. P values for individual variables shown only if multivariate GLMM analysis indicated an overall significant difference in that group of variables; ‘NS’ = no significant difference in the multivariate GLMM