Date of Award

2023

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Sherry L. Harrel

Abstract

Physical alterations of terrestrial habitat surrounding aquatic systems lead to increases in runoff, sedimentation, and nutrient inputs. Tracking changes in fish communities can provide information regarding degradation of water quality and the biotic integrity of freshwater systems. Changes in fish communities, and specifically declines in Buck Darter (Etheostoma nebra) populations, have been observed throughout the Buck Creek watershed since the 1980’s. Thus, goals of this project were to determine if shifts in fish community composition (eg., sensitive to less sensitive families, intolerant to tolerant species, and changes in feeding groups) and extirpation of the Buck Darter in 6 of 8 historically populated sub-watersheds are related to changes in land use/land cover (LULC) proportions from 1983, 2010, and 2020. LULC proportions were determined using GIS at a local and sub-watershed scale to discern (1) changes in fish communities relative to LULC between 1983 and 2012, (2) sub-watersheds for reintroduction of E. nebra based on historic LULC, and (3) streams in need of restoration relative to E. nebra conservation. A detrended correspondence analysis (DCA) was used to determine relationships between LULC and fish communities between years and spatial scales. A principal component analysis (PCA) of 1983 and 2020 LULC proportions was used to identify sub-watersheds for the reintroduction of E. nebra based on the least change from 1983 and stream buffers in need of restoration based on. Agriculture/pasture dominated LULC proportions in 1983, 2010, and 2020 at the watershed level. Intolerant fish species, invertivores, omnivores, herbivores and darter species distributions decreased in sub-watersheds dominated by agriculture/pasture LULC (>50%). Centrarchids occurred in sub-watersheds in 2012 where they were absent in 1983 and increased in abundance in streams that gained proportions of development. LULC proportions at the buffer level demonstrated riparian reforestation efforts occurring throughout the Buck Creek watershed from 1983-2010. With forest proportions higher in Crab Orchard Creek and Gilmore Creek in 2010, intolerant, invertivore, and darter species proportions still decreased. This suggests that changes in fish communities within the Buck Creek watershed are operating at the watershed scale. Results from a PCA demonstrated that Gilmore Creek and Crab Orchard Creek showed the least LULC change, and Brushy Creek remained associated with agriculture/pasture in 2020. With little change in LULC proportions observed between years, disturbance of the Buck Creek watershed occurred prior to 1983, with fish communities exhibiting a delayed response. Further reforestation of riparian buffers will reduce inputs of sediment and reduce inputs of organic and inorganic nutrients into tributaries of the Buck Creek watershed.

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