Road Culvert Impacts on Stream Fish Community Structure in Eastern Oklahoma

Abstract

Road culverts threaten the Ozarks and Ouachita Mountains regions of Oklahoma with habitat fragmentation and loss of aquatic biodiversity. This region of Oklahoma is understudied when it comes to this issue. Fishes within the pelagic spawning reproductive guild are highly impacted by fragmentation because they need long segments of free-flowing river to reproduce. Here, we explore how stream fish community composition varies with the presence of a stream crossing structure such as a culvert. We sampled 29 sites that contained a physical structure and 39 random sites that did not contain a physical structure. At each site, we measured a suite of physical and hydrological attributes of the stream system and sampled the fish community; in sites with a road-stream crossing, we also measured a suite of physical attributes of the structure, and sampled the fish community upstream and downstream of the structure. The presence of a stream crossing structure resulted in significant differences in species richness and abundance compared to unfragmented sites. We also discovered that vertical outlet drops negatively affect species richness and abundance from the upstream to downstream stream segments. Exploring the Bray-Curtis Dissimilarity, we saw that at our fragmented sites there had large differences in stream fish community composition. We also encountered Species of Greatest Conservation Need: Wedgespot Shiner (Notropis greenei), Cardinal Shiner (Luxilus cardinalis), and Black Buffalo (Ictiobus niger). This study presents new data on the effects of fragmentation on stream fishes in this region of Oklahoma. This data could be used to create a framework for conservation of stream fishes in this region and the methodology to undertake projects such as this. With many Ozark and Ouachita Mountain streams fragmented by stream crossing structures, the need for renovation of these structures to ones more suitable for fish passage would be a first step in conservation of these stream fishes