The main finding of the present study is the positive
correlation between L. stagnalis density (CPUE) and
Diplostomum sp. prevalence. This is in contrast to the
negative correlation between L. stagnalis density and
the prevalence of trematodes found by Puurtinen et al.
(2004). These authors included all trematode taxa
except Diplostomum, which was absent in mid-July.
High prevalence of trematode parasitism in snail
populations makes a remarkable proportion of snails