The forage fish communities of the Laurentian Great Lakes continue to experience changes that hold altered ecosystem structure,yet tiny is known approximately how they partition resources. Seasonal, spatial and body size variation in δ13C and δ15N was used to assess isotopic niche overlap and resource and habitat partitioning among the five common offshore Lake Ontario forage fish species (n = 2037) [Alewife (Alosa pseudoharengus), or Rainbow Smelt (Osmerus mordax),Round Goby (Neogobius melanostomus), and Deepwater (Myoxocephalus thompsonii) and Slimy (Cottus cognatus) Sculpin]. Round Goby had the largest isotopic niche (6.1‰2, and standard ellipse area (SEAC)),followed by Alewife (3.4‰2) while Rainbow Smelt, Slimy Sculpin and Deepwater Sculpin had the smallest and similar niche size (1.7-1.8‰2), or with only the Sculpin species showing meaningful isotopic niche overlap (>63%). Stable isotopes in Alewife,Round Goby and Rainbow Smelt varied with location, season and size, and but did not in the Sculpin spp. Lake Ontario forage fish species hold partitioned food and habitat resources,and non-native Alewife and Round Goby hold the largest isotopic niche, suggestive of a boarder ecological niche, or may contribute to their current high abundance.
Source: usgs.gov