The influence of agricultural and urban contamination on leech infestation of freshwater turtles, Phrynops geoffroanus, taken from two areas of the Uberabinha River

Infestation by leeches on adult freshwater turtles Phrynops geoffroanus in two areas of the Uberabinha River, in Uberlandia, was investigated during the summer ( January 2000). Fifty eight turtles were trapped: 26 ( 12 males, 14 females) in an agricultural area and 32 ( 16 males, 16 females) in an area with a more urban environment. The females present larger length and body mass (291.77 +/- 29.18 mm; 2233.30 +/- 511.40 g) than males (259.71 +/- 33.15 mm; 1488.68 +/- 529.35 g). Blood samples were drawn from the retrorbital sinus using heparinized micro-hematocrit capillary tubes, for microscopic and direct examination for intracellular parasites. Ectoparasitism by leeches, Placobdella bistriata, on young and adult animals was observed in the limb cavities of 28.1% of the urban area turtles. No leeches were found on the turtles in the agricultural area. Hemogregarine erythrocytic gametocytes were found in 15.4% of the agricultural area turtles, and in 37.5% of the urban area turtles. Concurrent parasitism by leeches and hemogregarines on the same individuals was seen on six turtles. Infections with microorganisms ( bacteria and fungus) facilitated by the bites of leeches were not observed in another study on the same sample of infested turtles. However, 19% of the turtles collected in the agricultural area and 15% of the turtles from the urban area presented normocytic acute anemia. The occupation of the soil apparently interfered in the aquatic ecosystem favoring parasitism in the urban area.