Seasonal variance in water quality, trace metals and infection variables of Cichlidogyrus philander Douëllou, 1993 (Monogenea, Ancyrocephalidae) infecting the gills of Pseudocrenilabrus philander (Weber, 1897) in the Padda Dam, South Africa

Abstract

Increasing awareness of deteriorating health of aquatic ecosystems, as a result of human activities, has led to the suggestion that fish host-parasite relationships are possible bioindicators of environmental pollution. This study examined the impact of water quality and trace elements on the seasonal occurrence of Cichlidogyrus philander Douëllou, 1993. In situ water quality variables were recorded, and sediment and water samples collected, for analysis of trace elements and metals. Collections were performed monthly from February 2016 to January 2017, during which 164 Pseudocrenilabrus philander (Weber, 1897) hosts were collected and their C. philander loads were counted. Monogeneans occurred throughout the year, with prevalence, mean intensity and abundance reaching maximum values of 90.74%, 29.9 and 29.4, respectively, in summer. Trace element and metal levels were highest in sediment and lowest in water. No significant correlation was found between water quality and trace elements on infection variables. Trace elements did not have an effect on the occurrence of the parasite, therefore it was concluded that the changes observed during the study were not brought on by changes in water quality as a result of pollution, but rather that these changes relate to seasonal variation in infection biology of C. philander.