Does mobility explain variation in colonisation and population recovery among stream fishes?

Abstract

Summary 1. Colonisation and population recovery are crucial to species persistence in environmentally variable ecosystems, but are poorly understood processes. After documenting movement rates for several species of stream fish, we predicted that this variable would influence colonisation rates more strongly than local abundance, per cent occupancy, body size and taxonomic family. We also predicted that populations of species with higher movement rates would recover more rapidly than species with lower movement rates and that assemblage structure would change accordingly. 2. To test these predictions, we removed fishes from a headwater and a mainstem creek in southwest Virginia and monitored colonisation over a 2‐year period. Using an information–theoretic approach, we evaluated the relative plausibility of 15 alternative models containing different combinations of our predictor variables. Our best‐supported model contained movement rate and abundance and was 41 times more likely to account for observed patterns in colonisation rates than the next‐best model. Movement rate and abundance were both positively related to colonisation rates and explained 88% of the variation in colonisation rates among species. 3. Population recovery, measured as the per cent of initial abundance restored, was also positively associated with movement rate. One species recovered within 3 months, most recovered within 2 years, but two species still had not recovered after 2 years. Despite high variation in recovery, the removal had only a slight impact on assemblage structure because species that were abundant in pre‐removal samples were also abundant in post‐removal samples. 4. The significance of interspecific variation in colonisation and recovery rates has been underappreciated because of the widely documented recovery of stream fish assemblages following fish kills and small‐scale experimental defaunations. Our results indicate that recovery of the overall assemblage does not imply recovery of each component species. Populations of species that are rare and less mobile will recover more slowly and will be more vulnerable to extinction in systems where chemical spills, hydrological alteration, extreme droughts and other impacts are frequent.

Climate change poised to threaten hydrologic connectivity and endemic fishes in dryland streams

“…Recent studies have supported the idea of heterogeneous movement by fish where populations consist of both stationary (represented by a high peak in the leptokurtic dispersal kernel and linked to the fish home range) and mobile (represented by the fat tail in the leptokurtic dispersal kernel and reflecting long-distance dispersal events) components (54). Mobile fishes are hypothesized to be responsible for facilitating the recolonization (i.e., rescue) of isolated habitats after major disturbance events and thus are decisive for genetic exchange and supporting long-term persistence (55). In our study, we interpret the passability of the temporary dry barrier when surface flow resumes as a function of a mobile fish's ability to disperse the distance of that rewetted channel (12).…”

Evaluating the effectiveness of restoring longitudinal connectivity for stream fish communities: towards a more holistic approach

“…Although such species do not migrate between different habitats they, like all river animals, rely on dispersal potential between habitat patches for population persistence and recolonization (Albanese et al 2009;Urban et al 2009;Pépino et al 2012;Radinger and Wolter 2014). Relatively little is known about the effect of longitudinal continuum restoration for river fishes, especially in degraded and rehabilitated habitats, despite its crucial importance for species distribution, species turnover and recolonization of newly available habitats (Detenbeck et al 1992;Albanese et al 2009) and for gene flow (Hanski 1998).…”

“…Relatively little is known about the effect of longitudinal continuum restoration for river fishes, especially in degraded and rehabilitated habitats, despite its crucial importance for species distribution, species turnover and recolonization of newly available habitats (Detenbeck et al 1992;Albanese et al 2009) and for gene flow (Hanski 1998). Our study showed that greatly improved dispersal potential was obtained for weak as well as strong swimmers at most restored sites, including all sites where obstacles were physically removed, showing the ecological value of such removals even when the obstacles are small.…”

Movement of logperch—the obligate host fish for endangered snuffbox mussels: implications for mussel dispersal

“…Rare and less mobile species will likely recover more slowly after local extinctions (Albanese et al 2009). Thus limited dispersal via small benthic host fish may provide an indication of extinction risk via habitat fragmentation (Strayer 2008).…”