Trace metal uptake and accumulation pathways in Kemp's ridley sea turtles (Lepidochelys kempii)
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Little is known of trace metal concentrations and their possible role in the mortality of critically endangered Kemp??s ridley sea turtles (Lepidochelys kempii). Research described herein characterized concentrations of seven trace metals ?? Ag, Cd, Cr, Cu, Hg, Pb and Zn ?? in the blood and carapace tissue of captive Kemp??s ridleys for use in assessing levels of these metals in wild counterparts. Concentrations of same trace metals were characterized in post-pelagic through adult life stages of 127 wild Kemp??s ridleys captured from the Gulf of Mexico and southeast Atlantic during 2000 to 2002. Blood, carapace, liver, kidney, and muscle tissues from live and/or stranded Kemp??s ridleys were analyzed for the aforementioned trace metals via graphite furnace atomic absorption spectrophotometer and cold vapor atomic fluorescence techniques conducted under class-100 clean laboratory conditions. Similar trace metal assessments were conducted on blue crab (Callinectes sapidus) prey to determine the role of food as a possible uptake pathway in Kemp??s ridleys. Overall, trace metal levels in live, captive as well as wild ridleys were higher in carapace tissue than in blood. Carapace concentrations of Ag, Cr and Hg in Kemp??s ridleys across all post-pelagic life stages increased with increasing straight carapace length (SCL). Carapace tissue of wild ridleys exhibited higher Cr, Hg, and Pb levels than their blue crab prey, regardless of study area; whereas, crabs yielded higher Ag and Cu concentrations. Dead stranded ridleys yielded higher Ag, Cr, Hg, Pb, Zn levels in carapace tissue, whereas, their liver exhibited higher Cd and Cu levels. This finding suggests carapace tissue could serve as a suitable surrogate sample source for internal organs/tissues when monitoring exposure of live Kemp??s ridleys to certain metals. The fact that larger, stranded ridleys exhibited higher Ag, Cd, Hg, Pb and Zn levels than did their smaller, live analogs from Texas and Louisiana implies that these older ridleys had increased opportunities to accumulate higher metal concentrations in their carapace tissue than did their younger conspecifics. This trend suggests that carapace tissue has the potential to accumulate trace metals while blood-borne concentrations reflect only recent exposure to trace metals.
Wang, Hui-Chen (2006). Trace metal uptake and accumulation pathways in Kemp's ridley sea turtles (Lepidochelys kempii). Doctoral dissertation, Texas A&M University. Texas A&M University. Available electronically from