Associations between organochlorine contaminant concentrations and clinical health parameters in loggerhead sea turtles from North Carolina, USA

Abstract

Widespread and persistent organochlorine (OC) contaminants, such as polychlorinated biphenyls (PCBs) and pesticides, are known to have broad-ranging toxicities in wildlife. In this study we investigated, for the first time, their possible health effects on loggerhead sea turtles (Caretta caretta). Nonlethal fat biopsies and blood samples were collected from live turtles for OC contaminant analysis, and concentrations were compared with clinical health assessment data, including hematology, plasma chemistry, and body condition. Concentrations of total PCBs (Sigma PCBs), Sigma DDTs, Sigma chlordanes, dieldrin, and mirex were determined in 44 fat biopsies and 48 blood samples. Blood concentrations of Sigma chlordanes were negatively correlated with red blood cell counts, hemoglobin, and hematocrit, indicative of anemia. Positive correlations were observed between most classes of OC contaminants and white blood cell counts and between mirex and Sigma TCDD-like PCB concentrations and the heterophil:lymphocyte ratio, suggesting modulation of the immune system. All classes of OCs in the blood except dieldrin were correlated positively with aspartate aminotransferase (AST) activity, indicating possible hepatocellular damage. Mirex and Sigma TCDD-like PCB blood concentrations were negatively correlated with alkaline phosphatase (ALP) activity. Significant correlations to levels of certain OC contaminant classes also suggested possible alteration of protein (increasing blood urea nitrogen, decreasing albumin:globulin ratio), carbohydrate (decreasing glucose), and ion (increasing sodium, decreasing magnesium) regulation. These correlations suggest that OC contaminants may be affecting the health of loggerhead sea turtles even though sea turtles accumulate lower concentrations of OCs compared with other wildlife.

Figure 1. Selected scatter plots of ranked data depicting significant Spearman rank correlations between health indicators and OC contaminants in juvenile loggerhead sea turtles captured in the summers of 2000 and 2001 from Core Sound, North Carolina. (A) Ranked blood concentration of ∑OCs versus ranked total WBC count estimated from blood smears (r_s = 0.453; p < 0.02). (B) Ranked concentration of ∑TCDD-like PCBs measured in fat biopsies (PCB congeners 105, 118, 156, and 157) versus ranked heterophil:lymphocyte ratio (r_s = 0.615; p < 0.05). (C) Ranked blood concentration of ∑OCs versus ranked BUN concentration (r_s = 0.409; p < 0.01). (D) Ranked blood concentration of ∑OCs versus ranked AST activity (r_s = 0.581; p < 0.001).