Tim Bartley on Homogenization of Freshwater Lakes
First published:10 September 2019 https://doi.org/10.1111/gcb.14829
Lake fish communities across the globe are being subjected to a wide array of anthropogenic pressures. Consequently, the composition of these communities is changing. In many cases, lake fish communities are exhibiting homogenization—an increase in similarity to nearby lakes due to species introductions and/or extinctions. Yet, the environmental drivers of homogenization remain unclear. For our recent work published in Global Change Biology, we investigated a suite of potential drivers of changes Ontario lake fish communities. By comparing fish communities in hundreds of lakes between two time periods (before 1983 and after 2008), we found that fish communities are indeed more similar now than they were historically. The main contributor to homogenization is the arrival of gamefish species, likely due to that human‐assisted migration. Surprisingly, many other factors, including climate change, appear to have had little impact on changes in fish community composition, although climate change may be making lakes more suitable for gamefish species. Because many of these gamefish species are large predators, this homogenization is likely to alter Ontario lake food webs, though the consequences of these alterations remain nebulous.
November 25, 2019