Predicting impact of freshwater exotic species on native biodiversity: Challenges in spatial scaling
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Date
1998
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Abstract
Global homogenization of biota is underway through worldwide introduction and establishment of nonindigenous (exotic) species. Freshwater ecologists should devote more attention to exotic species for two
reasons. First, exotics provide an opportunity to test hypotheses about what characteristics of species or habitats are
related to successful establishment or invasibility, respectively. Second, predicting which species will cause large
ecological change is an important challenge for natural resource managers. Rigorous statistical relationships linking
species characteristics to probability of establishment or of causing ecological impacts are needed. In addition, it is
important to know how reliable different sorts of experiments are in guiding predictions. We address this issue with
different spatial scales of experiments testing the impact of two predators on native snail assemblages in northern
Wisconsin USA lakes: an exotic crayfish, the rusty crayfish (Orconectes rusticus); and a native fish predator, the
pumpkinseed sunfish (Lepomis gibossus). For the crayfish, laboratory experiments, a field cage experiment, and a
snapshot survey of 21 lakes gave consistent results: the crayfish reduced abundance and species richness of native
snails. Laboratory and field experiments suggested that pumpkinseed sunfish should have a similar impact, but the
lake survey suggested little impact. Unfortunately, no algorithms exist to guide scaling up from small-scale
experiments to the whole-lake, long-term management scale. To protect native biodiversity, management of
freshwater exotic species should be targeted on lakes or drainages that are both vulnerable to colonization by an
exotic, and that harbour endemic species. Management should focus on preventing introduction because eradication
after establishment is usually not possible.
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Keywords
exotic species, crayfish, spatial scaling
Citation
Lodge, David M.; Stein, Roy A.; Brown, Kenneth M.; Covich, Alan P.; Bronmark, Christer; Garvey, James E.; Klosiewski, Steven P. "Predicting impact of freshwater exotic species on native biodiversity: Challenges in spatial scaling," Australian Journal of Ecology, v. 23, no. 1, 1998, pp. 53-67.