Date

2019

Major

Biology (B.S.B.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. James H. Roberts

Abstract

Studying the habitat use of Coastal Plain fishes enables us to develop a deeper understanding of how fishes thrive in this highly variable environment. Based on previous research by Dr. Roberts and his students, Coastal Plain fishes seem to sort into two groups: (1) species selecting stream reaches that continue to flow throughout the summer (i.e., fluvial species [F]) and (2) species occurring in streams that may stop flowing in late summer (i.e., nonfluvial species [NF]). For this study, I took a detailed look at eight of these species, spanning the F-NF gradient, and asked which environmental variables (e.g., water quality, stream size, adjacent land use) most influence species occurrence at the spatial scales of stream reaches and microhabitats. Habitat availability and use data came from electrofishing and habitat surveys of 25 sites sampled in summer 2016 and 12 sites re-sampled in summer 2018. At the reach scale, Random forest models indicated that F species consistently selected sites with higher dissolved oxygen, pH, and conductivity, whereas NF species tended to show the opposite pattern. Neither group showed consistent selectivity for stream-size, physical-habitat, or land-use variables. At the microhabitat scale, F species specialized on coarser substrate and higher velocity but showed no preference for large woody debris (LWD). In contrast, NF species specialized on low-velocity and high-LWD microhabitat configurations but showed no substrate selectivity. These findings suggest that habitat selection of Coastal Plain fishes is scale-dependent, and potentially interacts with morphology, feeding strategy, and water-quality tolerance.

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