Predicting impact of freshwater exotic species on native biodiversity: Challenges in spatial scaling

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.

Interactions between invasive crayfish and native river shrimp

“…Invaders can threaten native species through competition, predation and introduction of new diseases, causing negative impacts on the structure and functioning of ecosystems (Hobbs et al, 1989;Holdich, 1999). Freshwater crustaceans are one of the most documented groups of freshwater invaders and are responsible for declines and extinctions of native species throughout the world (Guan and Wiles, 1997;Lodge et al, 1998Lodge et al, , 2000Nyström et al, 2001, Westman et al, 2002. The red swamp crayfish, Procambarus clarkii (Girard, 1852) is endemic to southeastern North America and, with the exception of Australia and Antarctica, it was successfully introduced on every continent due to its food value and economic importance (Hobbs et al, 1989).…”

The feeding habit of the CyprinidaeRastrineobola argenteain its new habitat, lakes Bulera and Ruhondo, two Rwandan lakes (Eastern Africa)

“…It is known that introduction of exogenous species into ecosystems, which occurred quite often in the past (e.g. Lodge et al, 1998;Pardo et al, 2009), is now considered as one of the leading threats to the biodiversity of ecosystems (e.g. Sala et al, 2000;Baxter et al, 2004;Lasram and Mouillot, 2009;Leprieur et al, 2009).…”

Heading south: new records of the invasive quagga musselDreissena rostriformis bugensis(Andrusov, 1897) in France and further perspectives

“…Freshwater ecosystems are particularly impacted by these invasive species (Lodge et al, 1998;Orr, 2003). Among freshwater invertebrates, freshwater bivalve species are being introduced worldwide at an increasing rate, mainly because of human activities (Darrigran, 2002;Karatayev et al, 2007).…”