Parasite communities of two three-spined stickleback populations in subarctic Norway—effects of a small spatial-scale host introduction

Abstract

We compared metazoan parasite communities of an introduced three-spined stickleback (Gasterosteus aculeatus) population with the nearby source population in northern Norway to study differences and clarify if factors controlling parasite dispersal act on a small spatialscale. The two component communities were highly similar. All parasite taxa found in the source population also occurred in the introduced population illustrating high probability of successful parasite introduction on a small spatial scale. Among the parasites were the three-spined stickleback specialist Schistocephalus solidus and a massive occurrence in the eyes of non-lens-infecting trematodes found through genetic results to include Diplostomum gasterostei, D. baeri 2, and a non-encysted Strigeidae gen. sp. On the infracommunity level, mean abundance differed significantly between lakes with regards to Apatemon sp. and the two autogenic three-spined stickleback specialists Gyrodactylus arcuatus and Proteocephalus sp. (assumedly P. filicollis). Mean dissimilarity among infracommunities within lakes was also significantly lower than mean dissimilarity among infracommunities between lakes, which was primarily accounted for by the allogenic cestode Diphyllobothrium ditremum, G. arcuatus and Proteocephalus sp.. We expect that the differences found between the two lakes were caused by dissimilar water temperatures, and stickleback and copepod intermediate host densities. Some inter-lake differences in abiotic and biotic factors were thus present, but caused only quantitative differences between the two parasite communities. Mechanisms contributing to qualitative differences were on the other hand absent or had low importance believed to be caused by similar ecosystems, exposure to the same parasite species pool and geographical proximity of the two lakes. We suggest that mechanisms influencing parasite dispersal are less important on a small spatialscale causing high similarity between local parasite communities.