Impact of Bridges and Culverts on Stream Fish Movement and Community Structure

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Title: Impact of Bridges and Culverts on Stream Fish Movement and Community Structure
Author: Vander Pluym, Jennifer L.
Advisors: Jim Gilliam, Committee Member
David Eggleston, Committee Chair
Jay Levine, Committee Member
Ken Pollock, Committee Member
David Genereux, Committee Member
Abstract: This study was part of a larger, more comprehensive project assessing the effects of culvert designs on freshwater mussel habitat. Because many freshwater mussels depend on an obligate relationship with certain fish hosts to complete their life cycle as well as sole mechanism for dispersal, it is critical to identify obstacles to fish movement that, in turn, could negatively impact dispersal success of mussels. The primary goal of our study was to quantify the impact of four commonly used road crossings (bridge, arch culvert, box culvert, and pipe culvert) on stream fish abundance and diversity, as well as movement. We conducted a mark-recapture study in 16 streams located in the Piedmont region of the Cape Fear River Basin of North Carolina during the summer of 2004. Following electrofishing surveys, all fish were identified to species and measured to the nearest millimeter. Fish ≤ 30 mm total length (TL) were individually marked elastomer paint. These procedures were repeated four, eight, and 12 weeks after the initial sampling period. With the exception of species richness, all response variables: estimates of population size, species diversity, fish index of biotic integrity (FIBI), and Conditional Percent Movement (CPM) did not vary significantly with crossing type, position (upstream and downstream), or month. Downstream reaches of box culverts contained significantly higher species richness of stream fish than other crossing types. High diversity of stream fish downstream of box culverts may have been due to a scouring effect common below box and pipe culverts which results in pool formation and a possible change from benthic to pool fish species on a local level. The general lack of stream fish abundance and diversity responses to road crossings may be due to: the insensitivity of stream fish community variables (FIBI and diversity index) to anthropogenic effects, the overall resilience of fish communities, or the shifting baseline theory--fish communities having shifted to an impacted community prior to sampling. There were extremely low numbers of individuals that moved between stream reaches in the first study, therefore we conducted a second mark-recapture study using Passive Integrated Transponder (PIT) tags with remote antenna arrays on six streams, three streams with bridges and three streams with box culverts, during the summer of 2005. We surveyed each stream using electrofishing and marked all fish measuring ≥ 60 mm TL with an ISO PIT tag. Custom built antenna arrays, with weir nets to direct fish passage through the antenna loop, were installed in each stream either upstream or downstream of a given crossing and detected tagged fish continuously for 30 days. Estimates of mean percent movement of fish through box culverts (28.27% ± 12.24% SE) was almost half that of bridges (44.35% ± 8.77% SE); however, the percent tagged fish detected by the antenna for bridges and culverts showed no significant difference between the two crossing types. These results suggest that a larger study might detect a significant difference in fish movement through culverts as opposed to bridges. This application of PIT tags and remote antenna arrays proved a more effective and efficient use of research funding to assess stream fish movement through culverts and we recommend the antenna systems for further non-game fish research.
Date: 2006-04-27
Degree: MS
Discipline: Marine, Earth and Atmospheric Sciences

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