Historical changes in the fish communities of the Great Lakes

Session: 12. - History of Great Lakes Fish, Fisheries & Governance: Dr. Henry Regier's Legacy

Sara Campbell, University of Toronto, Ecology and Evolutionary Biology, [email protected]
Nicholas Mandrak, Biological Sciences, University of Toronto Scarborough, [email protected]

Abstract

As a result of the loss of native species and the spread of non-native species, fish communities are becoming increasingly homogenous globally. The glacial history of the Laurentian Great Lakes region has played a large role in shaping current patterns in the distribution of freshwater fish species in the area.  Given the limited time for dispersal out of refugia to occur since the last glaciation, recolonization may not yet be complete, especially when considering the increasing accumulation of non-native species.  Changes to the Great Lakes fish fauna have been well documented over time, with 21 extirpations of native species and 29 successfully established non-native species.  The addition and spread of non-native species and loss of native species has resulted in communities becoming more similar over time.  Here, we examined changes in the fish fauna of the Great Lakes over time to quantify taxonomic homogenization by calculating within and between community similarity using Jaccard’s similarity coefficient.  The Lake Superior fauna has changed the most (~23%) while the Lake Ontario fauna has changed the least (~12%) since 1870.  The similarity of the fish communities among basins has averaged 66-70% per decade, demonstrating changes in composition, but no substantial signals of homogenization.

4. Additional Keyword
Taxonomic homogenization

5. Additional Keyword
Species diversity

6. Additional Keyword
Freshwater fishes