Figure: Fish communities have species that may be quite sensitive to watershed change, such as this bull trout, or quite tolerant, such as suckers.

Winners and losers among fish when watersheds change

The motivationAnimals can play a key role in mobilizing or moving nutrients and energy throughout ecosystems. For instance, nutrients in freshwaters are often locked up in the bodies of plants and animals and inaccessible for use. Fish can mobilize these nutrients by consuming prey and then excreting the excess nutrients in a dissolved form. Thus, changes in fish communities could alter this nutrient recycling. What happens to these ecosystems when watersheds undergo human development?

The discovery – This study mapped fish nutrient recycling throughout the United States. Based on remote sensing data and analyses of large datasets on fish, Jonathan Moore at Simon Fraser University (SFU) and his colleague from the University of Washington examined how fish communities and their excretion shift as people pave watersheds. They discovered that when watersheds become more altered by people, some fish species struggle, while other species thrive. Together, this diversity in sensitivity to watershed changes maintains aquatic ecosystems.

Its significance – Natural communities may be more resistant to human impacts than we previously thought. The reality is that there is a lot of variation in how natural systems will respond to environmental degradation. Different systems likely differ in sensitivity. Preserving the connectivity and regional suites of biodiversity will likely enable communities to shift with global change and resist loss of ecosystem function.

Read the paper“Response diversity, nonnative species, and disassembly rules buffer freshwater ecosystem processes from anthropogenic change” by Moore, JW and Olden, JD. Global Change Biology 23(5): 1871-1880 (2017). DOI: 10.1111/gcb.13536

Website article compiled by Jacqueline Watson with Theresa Kitos