Patterns of ichthyofaunal connectivity in the Monongahela River Basin

We examined patterns of fish community connectivity among 40 Monongahela River tributaries and their mainstem junctions in southwestern Pennsylvania.  Twelve tributaries were excluded due to water quality impairments or physical blockages.  The remaining 28 were classified as either adventitious (orders 1-3) or ordered (orders 4-5) and their fish communities and respective mainstream junction communities were sampled using a variety of gears. The resulting data was analyzed using the Jaccard Coefficient of Similarity, cluster analysis, and Venn diagram.  Adventitious tributaries shared 29% and 82% of their faunal complements with the mainstem and ordered tributaries respectively, while ordered tributaries shared 70% of their ichthyofauna with the mainstem.  Fish communities of the adventitious tributary network were more distinct and isolated from the river mainstem than those of the ordered tributaries.  In a fractured riverscape such as that of the  Monongahela River Basin,  tributaries  supporting high biodiversity may warrant special conservation measures.