Trophic Niche of Invasive White Perch and Potential Interactions with Representative Reservoir Species

The trophic dynamics of invasive species can yield insights into the mechanisms of invasion success and aid in the prediction of potential impacts on established species. Additionally, the predicted effects of an invader may differ depending on how it integrates into the resident food web and whether its resource use changes throughout the invasion process. We investigated the trophic dynamics of populations of invasive White Perch Morone americana in three large North Carolina reservoirs and evaluated the potential for impacts on members of the resident fish community. Specifically, we used stable isotope and diet analyses to evaluate their trophic niche relative to three representative species in each reservoir chosen for their widespread range, potential overlaps with White Perch, recreational value, and representation of ecological guilds based on habitat and prey sources. The species were a native littoral generalist invertivore (Bluegill Lepomis macrochirus), native littoral piscivore (Largemouth Bass Micropterus salmoides), and stocked pelagic piscivore (Striped Bass Morone saxatilis or Walleye Sander vitreus, depending on their availability). Small (<70mm TL), medium (120-170mm TL), and large (>200mm TL) White Perch occupied different trophic positions, and these positions were generally consistent among reservoirs relative to the representative species. Small and medium White Perch had the largest niche areas and high diet overlap with Bluegill in two of three lakes, whereas large White Perch had moderate diet overlap with Striped Bass, Largemouth Bass, and Walleye. As a species, White Perch occupy a wide trophic niche, which may aid in successfully establishing invasive populations. However, White Perch use resources shared by other members of the fish community, which could lead to negative impacts on these species. Received May 29, 2012; accepted December 23, 2012