Effects of Interspecific Interactions on Infracommunities of Helminths Parasitizing Creek Chub (Semotilus atromaculatus)

Abstract

ABSTRACT: Natural infections of Allocreadium lobatum Wallin, 1909 (Trematoda), Proteocephalus sp. (Cestoda), Rhabdochona canadensis Moravec and Arai, 1971 (Nematoda), Paulisentis missouriensis Keppner, 1974 (Acanthocephala), and Schyzocotyle acheilognathi (Yamaguti, 1934) (Cestoda) in the intestine of creek chub (Semotilus atromaculatus) were analyzed to determine whether patterns of interspecific competition were evident. Data from nearly 2 decades of sampling from the same system were analyzed for patterns of co-occurrence and abundance consistent with negative interactions. Co-occurrence analyses (null models and logistic regression) did not detect negative associations among parasite species. Positive associations among species were more common in null model comparisons. Correlation analyses demonstrated some significant negative correlations between the abundances of pairs of parasite species in some samples, but the overwhelming majority of correlations were insignificant or positive. Previous work did not detect negative microhabitat interactions among the most common helminths studied herein, and together, these results suggest the parasite communities of creek chub in the study area are absent any substantial effect of antagonistic or other negative interspecific interactions. Differences in transmission rate, mode, and spatiotemporal variation are likely dominant processes explaining the patterns observed in the present investigation.