Lymnaea stagnalis (n = 703) were encountered in 22
of the 28 locations investigated (79% of the sites) and
Diplostomum sp. in 10 of the 22 snail populations, i.e.
in 36% of the 28 sites. In the pooled data, the
correlation between L. stagnalis density (CPUE) and
Diplostomum sp. prevalence was positive (Spearman
rs = 0.427; P = 0.047; n = 22) (Fig. 2). However,
as snail density and trematode prevalence vary
considerably between years and seasons, the data
were analyzed as three groups according to the
sampling month and year. The correlation between
L. stagnalis density and Diplostomum sp. prevalence
was positive but not statistically significant in all
three collections: June 1999, August 2005, and
August 2006 (rs = 0.311, P = 0.280; rs = 0.775,
P = 0.225; and rs = 0.400, P = 0.600, respectively)
(Fig. 2). This is based on only those sites (n = 22)
where L. stagnalis were encountered.