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Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department

Natural Resource Management

First Advisor

Brian D.S. Graeb

Abstract

River channelization has been shown to negatively impact riverine ecosystems by degrading aquatic habitat conditions, decreasing diversity of both fish and aquatic invertebrate assemblages and impairing fish recruitment. As knowledge of the negative impacts of channelization has increased, so have channel restoration efforts. We evaluated a recent channel restoration project on the Pecos River, New Mexico by comparing abiotic and biotic conditions among five reaches of river, including the restored reach, an unchannelized reach and a channelized reach all prone to streamflow intermittence and an unchannelized reach and channelized reach more perennial in nature. Our first objective was to assess reach-scale differences in aquatic habitat conditions and fish assemblage structure and diversity, as well as to assess mesohabitat associations of fish species. We found that aquatic habitat availability was greatest in the more perennial unchannelized reach and that little difference in habitat availability existed among other reaches. In addition, we found minimal differences in habitat diversity among reaches. Diversity of fish assemblages showed no difference among reaches and differences in fish assemblage composition among reaches were minimal. We found that pelagic-broadcast spawning species were associated with high velocity habitats of greater depth and volume, while demersal adhesive spawning species and live bearers were associated with low velocity habitats of lesser depth and volume. vi Our second objective was to assess reach-scale differences in nursery habitat availability, fish recruitment and abundance of potential prey items (i.e. meiofauna). We found that slackwater availability was greatest in unchannelized reaches and that differences in recruitment were noticeable for two fish species, the plains killifish (Fundulus zebrinus) and western mosquitofish (Gambusia affinis). Plains killifish exhibited greater recruitment in unchannelized reaches, while western mosquitofish exhibited greater recruitment in channelized reaches. The abundance of total potential prey items was greatest in the more perennial channelized reach. Collectively, channel restoration showed no improvement to aquatic habitat conditions, fish assemblage diversity and composition, provision of slackwater nursery areas, recruitment of early-juvenile fishes and provision of potential prey items. We feel that periods of low discharge and streamflow intermittence likely impaired our ability to effectively assess the restoration effort. Thus, we suggest that future restoration efforts focus on a more holistic approach that includes both physical channel restoration and flow regime restoration.

Library of Congress Subject Headings

Pecos River (N.M. and Tex.)--Channelization
Stream restoration--Environmental aspects--Pecos River (N.M. and Tex.)
Aquatic habitats--Pecos River (N.M. and Tex.)
Fish communities--Effect of habitat modification on--Pecos River (N.M. and Tex.)

Description

Includes bibliographical references (pages 65-73)

Format

application/pdf

Number of Pages

94

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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