Evaluating sampling methods and investigating distribution and richness of fish and amphibians in Missouri wetlands
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Freshwater wetlands are some of the most imperiled ecosystems on the planet, meaning species that depend on them are at great risk. In Missouri, wetland filling and drainage for agriculture and the elimination and degradation of floodplain wetlands due to river management projects account for the destruction of greater than 85 percent of the state's wetland area since the 1780's. River management projects, including damming, channelization, and levee construction, altered flow regimes and disrupted essential exchanges between the main channel and floodplain areas. Declines of wildlife populations spawned early conservation efforts aimed at protecting existing wetlands and replacing those already devastated. In Missouri, efforts to increase wetland area focused on establishing public wetland complexes where, in an attempt to restore ecological function, wetlands are actively managed with precise water level manipulation and soil disturbance. While management regimes have historically focused on providing habitat for waterbird species, these wetlands are home to variety of taxa, and agencies are beginning to encourage actions that provide resources for a range of wetland dependent species, including fish and amphibians. Development of efficient sampling procedures is essential for detecting fish and amphibian species using restored wetlands and evaluating how management actions meet the unique life-history needs of these species. In addition to understanding the impacts of management actions, it's also imperative we recognize how hydrologic characteristics of restored wetlands influence distribution and richness of fish and amphibian species. The objectives of this study were to 1) investigate how sampling method and wetland habitat characteristics influence measures of species richness, 2) determine the sampling effort needed to detect wetland species, and 3) investigate the influence of wetland hydrology, within wetland conditions, and upland habitat on species richness and distribution. We evaluated four sampling methods in 29 wetlands across three regions in the state of Missouri during spring and summer, 2015-1016. Results suggest that a single method, a mini-fyke net, is able to identify the majority of fish and amphibian species in Missouri wetlands with minimal effort but that consistent detection of amphibians across seasons may require additional samples with minnow traps or dipnets. Species richness measures were influenced by method, water depth, distance from shore, and vegetation density, as well as spatial and temporal variables. In general, 6-7 samples with a mini-fyke net detected the majority of fish and amphibian species in a wetland. In addition to spatial and temporal variables, wetland hydrologic connectivity and managed water source were the main factors structuring the distribution and richness of fish and amphibian wetland taxa. This study enhances our understanding of factors influencing fish and amphibian use of restored wetlands and provides conservation practitioners with information to help select the most efficient and effective fish and amphibian sampling methods to meet monitoring objectives.
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