Metacercariae of Clinostomum schizothoraxi Kaw, 1950 (Digenea: Clinostomatidae) in Carassius carassius (Linnaeus) under different environmental conditions.

This report addresses the possible impacts of local habitat characteristics on the metacercariae of Clinostomum schizothoraxi Kaw, 1950 infecting crucian carp, Carassius carassius (Linnaeus), from three lakes in Kashmir. The lakes chosen encompass an extremely wide gradient in trophic status--Manasbal (less polluted and mesotrophic), Dal (moderately polluted and eutrophic) and Anchar (strongly polluted and hypertrophic). The results indicate that infrapopulation-level descriptors of abundance of C. schizothoraxi in fish differed between the three lakes and revealed that the infection levels were greater at Anchar Lake. Furthermore, the prevalence, mean abundance and mean intensity of infection also changed during the period of investigation along the seasonal gradient of water temperature. The fact that the abundance patterns of the parasite differed in different populations of the same host provided a unique opportunity for a comparative study on the temporal variations in infection patterns attained during different seasons. In particular, the lake environments showed a high degree of variability in the density profiles of mollusc intermediate hosts and, thus, the differences in the infection status of crucian carp were derived on the basis of intermediate host population size which, in turn, was influenced by the trophic characteristics of the three lakes.