Parasites of non-native freshwater fishes introduced into England and Wales suggest enemy release and parasite acquisition

J. Robert Britton,Danny J. Sheath,Amy J. Reading,Chris F. Williams

doi:10.1007/s10530-015-0857-8

J. Robert Britton, Danny J. Sheath + Show 2 more

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https://doi.org/10.1007/s10530-015-0857-8

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Journal: Biological Invasions	Publication Date: Jun 24, 2015
Citations: 49	License type: CC BY 4.0

Affiliation: Bournemouth University, Environment Agency

Abstract

When non-native species are introduced into a new range, their parasites can also be introduced, with these potentially spilling-over into native hosts. However, in general, evidence suggests that a high proportion of their native parasites are lost during introduction and infections by some new parasites from the native range might occur, potentially resulting in parasite spill-back to native species. These processes were investigated here using parasite surveys and literature review on seven non-native freshwater fishes introduced into England and Wales. Comparison of the mean numbers of parasite species and genera per population for each fish species England and Wales with their native ranges revealed <9 % of the native parasite fauna were present in their populations in England and Wales. There was no evidence suggesting these introduced parasites had spilled over into sympatric native fishes. The non-native fishes did acquire parasites following their introduction, providing potential for parasite spill-back to sympatric fishes, and resulted in non-significant differences in overall mean numbers of parasites per populations between the two ranges. Through this acquisition, the non-native fishes also had mean numbers of parasite species and genera per population that were not significantly different to sympatric native fishes. Thus, the non-native fishes in England and Wales showed evidence of enemy release, acquired new parasites following introduction providing potential for spill-back, but showed no evidence of parasite spill-over.

Highlights

Introductions of non-native species raise concerns over the impacts they can have on native biodiversity, including predation pressure, increased competition and disruptions to ecosystem functioning (Hulme et al 2009; Pysek et al 2010)
The number of parasite species and genera present in the non-native fish in their native range that were present in these fish species in the introduced range was low, with only 8.5 % of the native parasite species recorded in both ranges (Table 1)
Of these parasites recorded in the introduced range, the following were new additions to the British freshwater fish parasite fauna (Kirk 2004): Thaparocleidus vistulensis and Ergasilus sieboldi in S. glanis (Reading et al 2011), Onchoceleidus dispar from L. gibbosus (Hockley et al 2011) and Ancyrocephalus pricei from A. melas

Summary

Introduction

Introductions of non-native species raise concerns over the impacts they can have on native biodiversity, including predation pressure, increased competition and disruptions to ecosystem functioning (Hulme et al 2009; Pysek et al 2010). Notwithstanding, the introduction process might filter out many of these parasites through, for example, only a small sub-set of free-living individuals of low parasite diversity being removed from the native range and/or their parasites having high host specificity, with these hosts absent in the new range (Torchin et al 2003). Of those parasites that are introduced, their consequences for the receiving ecosystem will vary according to factors including the complexity of their lifecycle, their ability to spillover to native species, and the extent of the natural resistance and resilience to infection in these new hosts (Kelly et al 2009)

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Conclusion