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. All present-day species arrived through active dispersal using corridors of suitable habitat once the ice sheet of the last glaciation began to recede. 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 community changes over time. This study reviewed the historical biogeography of the Great Lakes and examined temporal changes in taxonomic dissimilarity over 15 time periods spanning the last 150 years. Taxonomic dissimilarity between and within communities was calculated using Jaccard's dissimilarity coefficient and the relative contribution of turnover (species replacement) and nestedness (species loss) to total taxonomic dissimilarity was also calculated.
Results/Conclusions
Native species richness in the Great Lakes exhibits a latitudinal gradient that reflects postglacial history and current climate. The Lake Superior fauna has changed the most (~23%) while the Lake Ontario fauna has changed the least (~12%) since 1870. The dissimilarity of the fish communities among basins has averaged 50-53% per decade, demonstrating changes in composition, but no substantial signals of homogenization. Ongoing management should continue to prevent the range expansion of native and non-native species to preserve current distinctiveness of the Great Lakes fish communities.