Comparison of reproductive parameters in male yellow-blotched map turtles (Graptemys flavimaculata) from a historically contaminated site and a reference site.

From May to September of 1998, we collected monthly plasma samples from male yellow-blotched map turtles captured at two sites in the Pascagoula River drainage, Mississippi. One site (Vancleave) has a documented history of pollution from industrial sources (principally 2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD). Fish consumption advisories at the Vancleave site were lifted in 1996 and current impacts appear minimal. However, the yellow-blotched map turtle, a federally protected species, continues to decline in numbers. To determine if endocrine disruption could be a factor in the low reproductive rates observed in Vancleave turtles, we examined levels of plasma testosterone (T) and estradiol-17beta (E(2)) from males at this site and a second site (Leaksville), which has no known source of industrial pollution. Plasma was also tested for vitellogenin (VTG), which, in males, can be a biomarker of exposure to estrogenic contaminants. No males had detectable plasma VTG nor did mean monthly E(2) levels differ between sites. However, 10% of males from the historically polluted site were found to have high levels of E(2) (equivalent to levels found in females) and T was significantly lower for males captured at this site for 3 of 5 months. Our data suggest that the current impact of contaminants on reproduction in this population is limited. However, a portion of the population may have been affected developmentally, as represented by differences in reproductive parameters detected between sites.

Seasonal variation in reproductive steroids of male and female yellow-blotched map turtles, Graptemys flavimaculata.

From April to October of 1996 and 1997, we measured seasonal changes in plasma testosterone (T) in male and plasma T and estradiol-17beta (E(2)) in female yellow-blotched map turtles, Graptemys flavimaculata, from the Pascagoula River, Mississippi. In 1996, plasma from females was analyzed for progesterone. In 1997, ovaries of adult females were ultrasound imaged to determine stages of follicular development. Males exhibited peak T levels in September and October of both years, indicating fall gonadal activity. Males also exhibited a low level spring peak in T during April. Female E(2) levels increased significantly in May and June, the primary period of ovarian development. Females with preovulatory follicles did not have significantly higher E(2) levels than females with medium- or small-sized follicles. When compared to other freshwater turtle species, peak levels of E(2) were low. Testosterone levels did not follow a distinct yearly pattern in females. Progesterone levels were elevated in June when peak nesting was observed. Ultrasound and hormone data indicate that females lack ovarian development in the fall and produce on average only one clutch per year.

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and organochlorine pesticides in yellow-blotched map turtle from the Pascagoula River basin, Mississippi, USA.

Concentrations of polychlorinated-dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs), -biphenyls (PCBs), and organochlorine pesticides were measured in tissues of map turtles collected from two locations in the Pascagoula River drainage of Mississippi, USA. PCBs were most predominant among the organochlorines with a concentration of up to 99 ng/g, wet weight (580 ng/g, lipid weight) in livers. The greatest concentration of PCDDs/DFs of 1.1 pg/g, wet weight (15.76 pg/g, lipid weight) was found in the liver of a male turtle. The measured concentrations of organochlorines were less than those reported for turtles from the Great Lakes Basin and upper St. Lawrence River. PCBs contributed 90-99% of the total estimated 2, 3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs). Particularly, PCB congeners 105, 118, and 156 accounted for 68-80% of the estimated toxic potency of PCBs in turtles.