Across‐ecoregion analysis suggests a hierarchy of ecological filters that regulate recruitment of a globally invasive fish

Abstract

Aim Even successful invaders are abundant only in a fraction of locales they inhabit. One of the main challenges in invasion ecology is explaining processes that drive these patterns. We investigated recruitment of a globally invasive fish, common carp (Cyprinus carpio), across three ecoregions to determine the role of environmental characteristics, predatory communities and propagule pressure on the invasion process at coarse and fine spatial scales. Location Lakes across Northern Forest, Temperate Forest and Great Plains ecoregions of North America. Methods We used data from 567 lakes to model presence or absence of carp recruitment using environmental conditions (lake clarity, area, maximum depth), native predatory fishes (micropredators, mesopredators, large predators) and propagule pressure (abundance of adult carp). We formed a set of alternative models and evaluated their support using an information theoretic approach. Once most supported models were identified, we used classification tree to determine how variables included in these models interacted to affect carp recruitment. Finally, we conducted a field experiment to test the predictions of the classification tree analysis. Results Carp recruitment was strongly regulated by processes associated with water clarity, which appeared to function as a broad‐scale ecological filter. Carp were unlikely to recruit in clear, oligotrophic lakes (Secchi depth > 2 m) despite the presence of adults in many such systems. Recruitment was more likely to occur in regions with turbid lakes, but abundant micropredators could inhibit it there. Main conclusions Carp recruitment and invasions across large geographic areas are attributable to a two‐layer ecological filter with lake clarity/productivity acting as a coarse‐scale filter and micropredators acting as a fine‐scale filter. This two‐layer filter might explain the complex patterns of carp invasions among and within different ecoregions. Ecological filters may also explain the success of other aquatic invaders that show similarly patchy spatial distribution patterns.

Biological invasion by a benthivorous fish reduced the cover and species richness of aquatic plants in most lakes of a large North American ecoregion

“…Decline in plant diversity and cover also hinders fundamental ecosystem functions such as maintaining water clarity, reducing erosion or sequestering nutrients (Engelhardt & Ritchie, ; Haas et al ., ). The abundance of carp tends to be highest in hypereutrophic lakes in agricultural and urban areas (Kulhanek et al ., ,b; Bajer et al ., ). Although site‐specific studies have shown the effects of carp on aquatic ecosystems (Vilizzi et al ., ), it has not been demonstrated whether common carp can be prevalent and important enough to cause sweeping declines in diversity and ecosystem function across entire geographic regions.…”

Earning their Stripes: The Potential of Tiger Trout and Other Salmonids as Biological Controls of Forage Fishes in a Western Reservoir

“…Unintentionally introduced species can be detrimental to intentionally introduced fishes through predation or competitive interactions for shared prey resources (Gardunio et al 2011;Guy et al 2011). However, even intentionally introduced species may not be successfully established Williamson and Fitter 1996;Bajer et al 2015). Successful introductions, whether intentional or not, may initiate novel predator-prey interactions Romare and Hansson 2003;Schoen et al 2012), alter trophic structure (Reissig et al 2006;Skov et al 2010;Ellis et al 2011), or increase the potential for competition (Tyus and Saunders 2000;Tronstad 2008;Winters and Budy 2015).…”

Functional distance to recipient communities may favour invasiveness: insights from two invasive frogs

“…As discussed above, this hinders the identification of hierarchical structures in the controls of invasion (e.g. biotic interactions filtering out non‐natives at the local community scale, and environmental filters preventing or allowing them at the regional scale; Bajer et al ., ). Nevertheless, because spatial aggregation decreases variance, patterns that can be observed using our approach should be at least as clear using finer‐scale data.…”

“…Bullfrog tadpoles are also mostly unpalatable to predatory fishes (Kruse & Francis, ), but they are, however, vulnerable to predation by salamanders and dragonfly larvae (Werner & McPeek, ), and adult and juvenile bullfrogs are also frequently preyed by large vertebrates (Lannoo, ). Recent evidence suggests that environmental controls and predation pressure can interact and influence invasive fish at hierarchical spatial scales (Bajer et al ., ). Although this possibility could not be addressed in our case due to the nature of our data, increasing availability of large‐scale, spatially explicit databases should open opportunities to test, in the near future, if similar hierarchical filters exist in amphibian communities.…”