The roles of resource availability and competition in mediating growth rates of invasive and native freshwater snails
Riley, L.A.; Dybdahl, M.F. (2015). The roles of resource availability and competition in mediating growth rates of invasive and native freshwater snails. Freshwat. Biol. 60(7): 1308-1315. https://dx.doi.org/10.1111/fwb.12566
In: Freshwater Biology. Blackwell: Oxford. ISSN 0046-5070; e-ISSN 1365-2427, meer
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Interspecific relationships > Competition
Mammals > Carnivores > Fissipeda > Mustelidae > Mustela > Furbearing animals > Polecats
Potamopyrgus antipodarum (J. E. Gray, 1843) [WoRMS]; Pyrgulopsis robusta
Marien/Kust |
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- Riley, L.A.
- Dybdahl, M.F.
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| Abstract |
1. The classic paradigm in community ecology is that competition structures communities, limiting the number of species that can coexist. Under this paradigm, highly diverse communities should be biotically resistant to invasion. However, the importance of biotic resistance in repelling invasions might depend on resources because high resource availability can increase growth rates of invasive speciesand either reduce or increase competitive effects of invasive species on native community members.2. We tested how experimentally altered resource levels affected growth rates of an invasive (Potamopyrgus antipodarum) and a native snail (Pyrgulopsis robusta) and interspecific competition betweenthem. Potamopyrgus and Pyrgulopis are the dominant macroinvertebrates in streams within the range of the locally endemic Pyrgulopsis in Wyoming, U.S.A.3. In the absence of competition, we found that Potamopyrgus always grew faster than Pyrgulopsis at both high and low resource levels. In the presence of interspecific competition, Potamopyrgus growth rates were not affected by resource levels or the biomass of Pyrgulopsis competitors. On the other hand, Pyrgulopsis grew slower at low resource levels and especially when the biomass of Potamopyrgus competitors was high.4. These results indicate that negative effects of Potamopyrgus on Pyrgulopsis growth rates were stronger at low resource levels. In contrast, Pyrgulopsis did not reduce Potamopyrgus growth under any resource scenario. Thus, increased resource availability seems to mitigate strong competitive effects of Potamopyrgus on the native snail in this stream. |
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