Physiographic and Anthropogenic Factors Influencing Fish Community Composition in Tributaries to the Youghiogheny River in Pennsylvania

Abstract

Abstract We evaluated the status of fish communities from 30 first- to fourth-order wadeable Youghiogheny River (YR) tributaries located in the Allegheny Mountain Section (AMS) and Pittsburgh Low Plateau (PLP) physiographic provinces in Pennsylvania. The AMS is underlain primarily by geologic formations dominated by the Allegheny Group, while the Casselman Formation underlies much of the PLP. Streams draining the AMS were primarily forested, low-order (1–2), high-gradient, and poorly-buffered with minimal cultural influences. By contrast, the majority of the PLP was drained by low-gradient, well-buffered, valley streams of order ≥2, with varying anthropogenic influences. In order to characterize connectivity, all streams were sampled from their mainstream junctions to an endpoint 200 m upstream utilizing back-pack electrofishing. A total of 366 fishes representing seven families, 17 genera, and 22 species were collected from AMS streams, while the PLP yielded 2738 fishes representing 8 families, 25 genera...