Guide to the Parasites of Fishes of Canada Part V: Nematoda.

Keys are provided for the identification of the nematode species known to be parasites of Canadian fishes. The nematodes are described and illustrated, with a note of the site(s) they occupy in named fish host(s) and their geographical distribution. Parasite records are given by author and date, full details of which can be found in a bibliography of over 800 references. Diagnoses and keys for 22 Families, 47 genera and 88 species of nematodes are also given, together with a glossary of terms, a host-parasite list, and indices to both nematode parasites and hosts.

Development of nestedness: host biology as a community process in parasite infracommunities of yellow perch (Perca flavescens (Mitchill)) from Garner Lake, Alberta.

Infracommunity data from 60 perch collected from Garner Lake, Alberta, in 1992 were examined to determine whether ontogenetic shifts in host diet or habitat could produce a nested subset pattern of infracommunity structure. The host by parasite matrix showed significant nesting. Host idiosyncratic temperatures, which are indicative of differing "biogeographic histories," were determined primarily by the presence of Ergasilus caeruleus in depauperate communities, or its absence in richer communities, and covaried positively with host age and the associated variables of host length, mass, and infracommunity richness. Idiosyncratic host temperatures did not differ significantly between male and female perch when the effect of age was controlled for by analysis of covariance. Although an ontogenetic diet shift can be ruled out as producing the observed nested pattern, it is possible that the observed nested subset pattern is the result of an ontogenetic habitat shift.