Metal accumulation and evaluation of effects in a freshwater turtle

Abstract

A variety of contaminants have been detected in aquatic and terrestrial environments around the Paducah Gaseous Diffusion Plant (PGDP), Kentucky. The presence of these contaminants at the PGDP may pose a risk to biota, yet little is known about the bioaccumulation of contaminants and associated effects in wildlife, especially in aquatic turtles. The current study was initiated to evaluate: (1) the accumulation of heavy metals (Cd, Cr, Cu, Pb, and Hg) in aquatic ecosystems associated with the PGDP using red-eared slider turtle (Trachemys scripta elegans) as biomonitors; (2) maternal transfer of heavy metals; and (3) potential hematological and immunological effects resulting from metal accumulation. A total of 26 turtles were collected from 7 ponds located south, adjacent, and north of the PGDP. Liver Cu concentrations were significantly different among ponds and Cu concentrations in eggs were positively correlated with female Cu concentrations in kidney. The concentrations of heavy metals measured in turtle tissues and eggs were low and, based on previous studies of reptiles and established avian threshold levels of heavy metals, did not appear to have adverse effects on aquatic turtles inhabiting ponds near the PGDP. However, total white blood cell counts, heterophil to lymphocyte ratio, and phytohemagglutinin stimulation index were correlated with metal concentrations. Because other factors may affect the hematological and immunological indices, further investigation is needed to determine if these effects are associated with metal exposure, other contaminants, or disease.

Body burdens of heavy metals in Lake Michigan wetland turtles

“…Our results support the use of tissue metal concentrations in turtles as toxicological sentinels in aquatic environments, a technique that has been suggested by numerous researchers but has rarely been implemented in monitoring programs (Tryfonas et al 2006;Yu et al 2011). Further, our finding that some metals appear to accumulate in external tissues (i.e., claw and shell), with concentrations that correlate with internal tissues, suggests that non-lethal sampling could be used to monitor heavy metals in the environment.…”

“…Painted and snapping turtles in our study wetlands contained measurable concentrations of all metals analyzed (cadmium, chromium, copper, iron, lead, magnesium, manganese, and zinc), some of which may cause physiological stress (Yu et al 2011). Our results support the use of tissue metal concentrations in turtles as toxicological sentinels in aquatic environments, a technique that has been suggested by numerous researchers but has rarely been implemented in monitoring programs (Tryfonas et al 2006;Yu et al 2011).…”

“…Available data, however, suggest that the Lake Michigan wetland turtles that we analyzed had metal concentrations that were generally similar to turtles in other human-impacted systems, although concentrations differed markedly for some metals in some tissue types. For example, chromium and copper concentrations in muscle and liver tissues of the turtles in our study (both species) were very similar to concentrations in muscle and liver tissues of red-eared sliders (Trachemys scripta elegans) from the Paducah Gaseous Diffusion Plant superfund site in western Kentucky (Yu et al 2011). However, liver copper concentrations in our turtles were three to five times higher than liver copper concentrations found in Caspian pond turtles collected from the Gharehsu River in Iran (Yadollahvand et al 2014).…”

Accumulation of Polychlorinated Biphenyls (PCBs) and Evaluation of Hematological and Immunological Effects of PCB Exposure on Turtles

“…Keller et al (2004a) reported lipid content from 0.255 % to 64.7 % in loggerhead turtles captured in Core Sound, North Carolina. It is possible that some turtles did not eat and therefore lost fat reserves when kept in captivity 5-10 days (food was provided ad libitum) during egg induction and PHA skin tests (Yu et al 2011). Among the 26 PCB congeners evaluated in all samples, seven congeners were above detection limit including 3 mono-ortho congeners (PCB 28, 118, and 123) and 4 di-ortho congeners (PCB 101, 153, 170, and 180).…”

“…Phytohemagglutinin (PHA) skin test was also conducted to determine stimulation index (PHA SI), which is an indication of T-cell mediated immunity. Trapping, blood collection, and determination of hematological and immunological parameters have been described in detail in Yu et al (2011). Hematology and PHA SI were only determined in turtles collected in 2008.…”