Invasive Species Appearance and Climate Change Correspond with Dramatic Regime Shift in Thermal Guild Composition of Lake Huron Beach Fish Assemblages

Abstract

Lake Huron has undergone dramatic and well-documented lake-wide food web changes as a result of non-native species introductions. Coastal beaches, which serve as nursery habitats for native and introduced species, are, however, relatively poorly studied. Our objective was to assess fish assemblages of beach habitats in western Lake Huron and compare species composition pre- (1993) and post-invasion (2012) of dreissenid mussels and round goby (Neogobius melanostomus). Nearshore beach fish assemblages were sampled by nighttime beach seining during spring and summer in 1993 and 2012 in the western basin of Lake Huron along the Michigan shoreline. Catch rates were considerably higher, but there were fewer species present in 2012 than in 1993. The composition of species changed dramatically from a cold- and cool-water species assemblage in 1993 (dominated by alewife (Alosa pseudoharengus), spottail shiner (Notropis hudsonius), and lake whitefish (Coregonus clupeaformis), as well as Chinook salmon (Oncorhynchus tshawytscha) and rainbow smelt (Osmerus mordax)) to a cool- and warm-water species assemblage in 2012 (dominated by cyprinids, round goby (Nogobius melanstomus), and yellow perch (Perca flavescens)). The observed rise in catch rate and shift in species composition appears related to the introduction of invasive species as well as an on-going warming pattern in nearshore waters.