Investigating the Role of Long Distance Dispersal in the Response of Stream Fishes to Urbanization
I conducted a 7-month mark-recapture study in two watersheds differing in urban impact in order to assess the role that long distance dispersal plays in the response of tolerant stream fishes to urbanization. Our two stream sites included a heavily impacted urban stream (watershed impervious surface cover ~30%) and a mildly impacted rural stream (watershed impervious surface cover ~6%). Species of interest were marked with 12mm HPT PIT tags and included a specialist, Campostoma oligolepis (n=189 urban site, 200 rural site) and a generalist, Lepomis auritus (n=136 urban site, 182 rural site). Three resampling instances for each site were conducted between September of 2016 and February 2017 with a portable PIT antenna. Movement data was analyzed with R package Mclust to estimate the proportion of mobile and stationary components for each population as well as parameter estimates (mean, variance) for each component. L. auritus in the urban site exhibited a greater proportion of long distance dispersal than in the rural site, and the rural population did not fit a heterogeneous model better than a homogeneous model. C. oligolepis had a greater proportion of long distance dispersal in the rural site, but both the mobile and stationary components had a significantly greater mean movement distance in the urban site (mobile component mean=217m urban, 131m rural; stationary component mean=51m urban, 21m rural). Tolerant generalists may increase long distance dispersal but not home range movement in urban streams while specialists may increase movement distances for both home range and long distance dispersal.
stream urbanization, fish movement, stream ecology, Biology, Integrative Biology, Population Biology, Terrestrial and Aquatic Ecology
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