Abstract
The effects of disturbance on local species diversity have been well documented, but less recognized is the possibility that disturbances can alter diversity at regional spatial scales. Since regional diversity can dictate which species are available for recolonization of degraded sites, the loss of diversity at regional scales may impede the recovery of biodiversity following a disturbance. To examine this we used a chemical disturbance of rotenone, a piscicide commonly used for fish removal in aquatic habitats, on small fishless freshwater ponds. We focused on the non-target effects of rotenone on aquatic invertebrates with the goal of assessing biodiversity loss and recovery at both local (within-pond) and regional (across ponds) spatial scales. We found that rotenone caused significant, large, but short-term losses of species at both local and regional spatial scales. Using a null model of random extinction, we determined that species were selectively removed from communities relative to what would be expected if species loss occurred randomly. Despite this selective loss of biodiversity, species diversity at both local and regional spatial scales recovered to reference levels one year after the addition of rotenone. The rapid recovery of local and regional diversity in this study was surprising considering the large loss of regional species diversity, however many aquatic invertebrates disperse readily or have resting stages that may persist through disturbances. We emphasize the importance of considering spatial scale when quantifying the impacts of a disturbance on an ecosystem, as well as considering how regional species loss can influence recovery from disturbance.
Highlights
Given the magnitude of anthropogenic activities on natural systems (Vitousek et al, 1997), understanding if and how biodiversity recovers from disturbances is an important focus of ecology and conservation biology
The addition of rotenone had a significant effect on local species richness (p < 0.008, F1,10 = 11.20, Table S1; Fig. 2), but this effect varied across sampling dates
We found that rotenone causes a significant short-term loss of aquatic species richness at local and regional scales, resulting in changes to aquatic community structure
Summary
Given the magnitude of anthropogenic activities on natural systems (Vitousek et al, 1997), understanding if and how biodiversity recovers from disturbances is an important focus of ecology and conservation biology. The loss and recovery of biodiversity in response to disturbances has been extensively studied in multiple systems (Niemi et al, 1990; Yount & Niemi, 1990; Lake, 2000; Chazdon, 2003; Dunn, 2004; Flinn & Vellend, 2005). Less recognized is the possibility that short-term, widespread environmental disturbances can alter species diversity at regional scales, or that species composition can be altered (Hamer & Hill, 2000; Smith, Lips & Chase, 2009). Because regional diversity can dictate which species are available to recolonize degraded sites (Palmer, Ambrose & Poff, 1997; Zobel, Van der Maarel & Dupré, 1998), the loss of diversity at regional scales has important implications to restoration ecology and the recovery of biodiversity after disturbances
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