Feeding ecology and niche overlap of Lake Ontario offshore forage fish assessed with stable isotopes

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 75; no. 5; pp. 759 - 771
• Main Authors: Mumby, James A, Johnson, Timothy B, Stewart, Thomas J, Halfyard, Edmund A, Weidel, Brian C, Walsh, Maureen G, Lantry, Jana R, Fisk, Aaron T
• Format: Journal Article
• Language: English
• Published: Ottawa NRC Research Press 01.05.2018; Canadian Science Publishing NRC Research Press
• Subjects: Alosa pseudoharengus; Biological competition; Body size; Competitors; Cottidae; Cottus cognatus; Ecological monitoring; Ecological niches; Ecosystem disturbance; Ecosystem structure; Environmental aspects; Environmental factors; Fish; Fish populations; Food and nutrition; Food chains; Foods; Forage; Forage fishes; Forage species; Foraging habitats; Freshwater; Geographical distribution; Habitat selection; Habitats; Isotopes; Lakes; Myoxocephalus; Myoxocephalus thompsonii; Neogobius melanostomus; Niche overlap; Niches; Niches (Ecology); Observations; Osmerus mordax; Seasonal variation; Species; Stable isotopes; Canada; Lake Ontario; Canada, Ontario, Lake Ontario
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/cjfas-2016-0150

The forage fish communities of the Laurentian Great Lakes continue to experience changes that have altered ecosystem structure, yet little is known about how they partition resources. Seasonal, spatial, and body size variation in δ 13 C and δ 15 N 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), rainbow smelt (Osmerus mordax), round goby (Neogobius melanostomus), and deepwater (Myoxocephalus thompsonii) and slimy (Cottus cognatus) sculpins). Round goby had the largest isotopic niche (6.1‰ 2 , standard ellipse area), followed by alewife (3.4‰ 2 ), while rainbow smelt, slimy sculpin, and deepwater sculpin had the smallest and similar niche size (1.7‰ 2 –1.8‰ 2 ), with only the sculpin species showing significant isotopic niche overlap (>63%). Stable isotopes in alewife, round goby, and rainbow smelt varied with location, season, and size, but did not vary in the sculpin species. Lake Ontario forage fish species have partitioned food and habitat resources, and non-native alewife and round goby have the largest isotopic niche, suggestive of a boarder ecological niche, and may contribute to their current high abundance.