Characterizing Changes in Energy Pathways Leading to Smallmouth Bass and Rock Bass Resulting From the Round Goby Invasion of Great Lakes Tributaries

The secondary invasion of the round goby (Neogobius melanostomus) into Great Lakes tributaries may be causing changes to riverine food web dynamics. Previous studies have found elevated predation of round gobies by smallmouth bass (Micropterus dolomieu) in many areas of the Great Lakes where they co-occur, but this relationship is relatively unknown in lotic environments. This study uses stable isotope analysis, gut content analysis, and fish assemblage data to help understand the consequences of the round goby invasion to the energy pathways leading to two lotic predators, smallmouth bass and rock bass (Ambloplites rupestris) in three Saginaw Bay, Lake Huron tributaries. We investigate how predator trophic position and degree of round goby predation correlates within a gradient of round goby abundances. Round gobies are known to harbor elevated contaminant concentrations thus high use as prey by top predators has implications to human health and food web bioaccumulation. Using stable isotopes to detect such food web changes can be an important tool in the study of invasive species impacts to riverine ecosystems.