Date of Graduation

2016

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Stuart Welsh

Committee Co-Chair

Dan Cincotta

Committee Member

Michael Strager

Abstract

This thesis examines the distribution and habitat use of two sympatric sand darter species, the western sand darter (Ammocrypta clara) and the eastern sand darter (A. pellucida). This thesis includes three chapters: (1) an introduction and literature review on the western and eastern sand darters, habitat use, and species distribution models; (2) a substrate selection laboratory experiment; and, (3) an evaluation of sympatric sand darter habitat use at multiple scales in the Elk River. Sand darters are slender, sand-dwelling fishes that were once broadly distributed, but have since undergone range-wide population declines, presumably owing to habitat loss. Habitat use studies have been conducted for the eastern sand darter, but literature on the western sand darter remains sparse, and is an essential element for the conservation of the species. The laboratory study (chapter 2) evaluated substrate selection for each species by conducting 15 trials in four aquaria; two aquaria contained six western sand darters in each, while the other two held a combination of both species, three eastern sand darters and three western sand darters. The sand darters were given the choice to bury into five equally available and randomly positioned substrates: fine sand (0.12-0.25 mm), medium sand (0.25-0.5 mm), coarse sand (0.5-1.0 mm), very coarse sand (1.0-2.0 mm), and granule gravel (2.0-4.0 mm). The western sand darter selected for coarse and medium sand, while the eastern sand darter was more of a generalist selecting for fine, medium, and coarse sand. Substrate selection was significantly different (p = 0.02) between species in the same environment, where the western sand darter selected for coarser substrate more often compared to the eastern sand darter. The habitat use assessment (chapter 3) addressed the distribution, sandbar habitat use, and landscape scale analysis of sand darter habitat in the lower 190 river km of the Elk River. A total of 63 sites were sampled. Western sand darters were detected at eight sites, eastern sand darters were detected at 47 sites, and neither species was detected at 14 sites. The two species were sympatric at six sites. At the sandbar scale, western sand darters were detected in sandbars with greater area, higher proportions of coarse grain sand and faster average current velocity, while the eastern sand darter was more of a generalist using a wider range of sandbar habitats. The landscape-level analysis revealed that drainage area was an important predictor for both species, while sinuosity also contributed to the western sand darter's habitat suitability. Sandbar quality (area, grain size, and velocity) and fluvial geomorphic variables (drainage area and sinuosity) are likely key driving factors structuring sand darter distributions in the Elk River. This multiscale study of species substrate selection, distribution and habitat use is unique, given that only a few sympatric populations are known of western and eastern sand darters.

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