Effect of Heavy Metals On Fresh Water Turtles of a Sludge-Amended Lake in South Texas.

Bioaccumulation of metals in reptiles has been reported to be higher when compared to birds and mammals; some species of reptiles are used as biomonitors for heavy metals. Turtles are exposed to heavy metals mainly via ingestion, dermal contact, inhalation, and maternal transfer. Polluted water can also be absorbed through the skin. In addition, age and sex dependent differences in diet, movement, activity patterns, and microhabitat use can all affect exposure. A 600-acre fresh water lake located in south Texas, which was used to discharge waste activated sludge and treated effluents for several decades, was the site of the current study. Continuous disposal of sludge in the lake and the adjoining basins and polders resulted in reduction of lake depth to less than two meters, causing odorous algal blooms and poor water quality. Due to the high cost of remediation, the owners chose to let the property revert to its natural state. This created a man-made 600-acre wetland, which has been turned into a wildlife refuge. In addition to a large number of migratory birds, the property is home to five confirmed turtle species. No research into the effects of sludge disposal has been undertaken on any organism on this property. Most research related to heavy metal exposure in turtles so far has focused on embryos and eggshells. Virtually no reports are available on the accumulation of heavy metals in adult turtles. Two species of freshwater turtles the Red-eared Slider (Trachemys scripta elegans), and the Texas river cooter (Pseudemys texana) were considered in this study. Blood and liver samples were analyzed for heavy metals through an Inductively-Coupled Plasma Mass Spectrometer. Water and sediment samples were also collected from the corresponding trapping sites and analyzed. Bioconcentration factor was calculated in relation to the food habits of the turtles.