TRACE ELEMENT CONCENTRATIONS IN BLOOD AND SCUTE TISSUES FROM WILD AND CAPTIVE HAWAIIAN GREEN SEA TURTLES (CHELONIA MYDAS)
Katherine R. Shaw, Jennifer M. Lynch, George H. Balazs, T. T. Jones, Jeff Pawloski, Marc Rice, Amanda French, Jing Liu, David Klein
Hawaiian green sea turtles (Chelonia mydas) are exposed to trace elements through water, sediment, and food. High concentrations of elements have been shown to decrease immune function, impair growth, and decrease reproduction in wildlife. This study compares trace element concentrations in green turtles living in captivity at Sea Life Park Hawaii (SLPH, n = 6) to wild green turtles in Kapoho Bay, HI (n = 5 to 7). To determine elemental concentrations, blood and scute samples were collected and analyzed for eleven elements via inductively coupled plasma-mass spectrometry (ICP-MS). Scute elemental concentrations in all turtles from greatest to least were Sr > Cu > Cr > V > Se > Ni > As > Pd > Cd > Co and in blood were Sr > Cu > Se > Pb > Ni> As > V > Cd > Co. Antimony was below detection in most blood and scute samples; and Cr was below detection in all but one blood sample. Seven elements were significantly different between captive and wild turtles. Selenium was significantly greater in the blood of captive turtles than wild turtles, while V, Ni, and Pb were significantly greater in the blood of wild turtles. In scute, V, Cu, Se, and Cr were significantly greater in captive turtles, while As was significantly greater in wild turtles. Pelleted food fed to the captive turtles and representative samples of the wild turtle diet were analyzed via ICP-MS to calculate trophic transfer factors (TTF) and daily intake values. TTFs > 1 indicated that V, Cr, and Sr potentially biomagnify in scutes of captive turtles; and Se in the scute and blood of wild turtles. Wild turtles had greater estimated daily intake than captive turtles of all elements except Cu and Se. Water samples were collected from the pond at SLPH and measured for trace elements. Four elements were detected in the seawater: Sr > Cu > Se > Cr. However, the main source of exposure to sea turtles is through their food source. Even though Se, Cu and V are essential elements, they are a possible husbandry concern because concentrations are significantly greater in the captive turtles. No toxic thresholds are known for sea turtles, but rehabilitation and managed care facilities should monitor sea turtle elemental concentrations to ensure the health of the animals.