Over the course of the past several weeks, most of the blog posts have consisted of information about how climate change is affecting saltwater aquatic species. Today’s blog will divert from that trend, and will consist of information about how freshwater species in the United States are being affected due to our changing climate.
The first region of the country that we will focus on is the Southeastern U. S. and the Gulf Coast. Before discussing the ways that climate change is affecting the freshwater species, lets begin by examining the landscape and climate of the region. A significant portion of the Southeastern United States is comprised of a large coastal plain. Most of the region experiences a warm humid climate that leads to plentiful precipitation and runoff, especially during the summer months. South Florida is the one area that has a distinct seasonal change in precipitation with abundant summertime rainfall and dry weather during the winter. Because of the large amount of runoff during the summer months, most of the Southeastern U.S. experiences a high rate of evapotranspiration. Although precipitation is likely to increase, runoff is expected to decline over the region, causing evapotranspiration to exceed precipitation levels. Florida and the Gulf Coast are the only areas where precipitation is anticipated to exceed evapotranspiration, leading to increased runoffs.
One of the affects that climate change is expected to have on freshwater species in the region is a decrease in habitat for species that thrive in cool water, especially for fish and macroinvertebrates that live in Appalachian streams. The video above offers some additional information about how freshwater ecosystems are affected by climate change. Climate change will also increase the likelihood for subtropical species to begin expanding northward. This includes a number of nuisance species that currently live only in southern Florida (Best et al.)
Next we will examine how climate change is likely to affect fish species in the Great Lakes and Northeast region. Fish are particularly sensitive to changes in the water temperature. For this reason they are particularly vulnerable to climate change. According to a study from the Environmental Law and Policy Center, the Great Lakes have experienced warming by a quantity of 1.6 degrees Fahrenheit from 1985 – 2016, which is higher than the national average of 1.2 degrees Fahrenheit. According to Erin Tracy, a researcher for the U. S. Geological Survey Arizona Cooperative Fish and Wildlife Unit, “managers need more information about how climate change is going to affect rivers in the future”. Tracy also stated that “one way to get this kind of information is to estimate how naturally resilient these rivers are to disturbances, such as climate change.” To assess the resilience of the rivers, Tracy and her partner Michigan State University professor Dana Infante examined primarily natural landscape factors, but also examined diversity of the habitat and anthropogenic factors. Some of the factors they examined included forest cover, catchment size, coarse geology, length of streams, and stressors caused by human activity.
Hao Yu analyses many of the same factors as Tracy to develop eight statistical distribution models of 55 fish species in 22 different states from Minnesota to the Atlantic Coast, including the state of Michigan (See image above).This research project is being conducted for the USGS Northeast Climate Adaptation Science Center. “These models give us different scenarios in the future with different air temperatures and precipitation values,” Yu said. “Based on different scenarios, we’ll get different predictions of how various climate change factors can affect fish distributions.” Infante stated that “This research looks at where fish currently occur based on land use, geology and climate. It predicts where fish might be in the future and how their habitats are likely to change with different climate change projections,” She also said that “It’s a really large-scale analysis at the types of changes, specific to fish, that we think could happen as a result of climate change.” According to Yu, some fish are sensitive to air temperature changes, while others have more sensitivity to precipitation changes. Yu’s work indicates that species along the Atlantic coast have a higher likelihood of being affected by climate change. He also mentions that warm water species such as largemouth bass and yellow bullhead would have the greatest gain in habitat, while cold water species such as brook trout have a greater chance of experiencing a decrease in habitat (Tekip).
Tekip, Alex. Examining the impacts of climate change on freshwater fish. https://www.canr.msu.edu/news/examining-the-impact-of-climate-change-on-freshwater-fish February 4, 2021. Web. April 6, 2022.
Best et al. Effects of climate change on freshwater ecosystems of the South – eastern United States and the Gulf Coast of Mexico. https://pubs.er.usgs.gov/publication/70019748. Web. April6, 2022.
Image: https://www.canr.msu.edu/fw/uploads/images/NortheastUS_USGSMap.jpg?language_id=1. Image. Retrieved April 6, 2022.
Video: Impacts to Freshwater Aquatic Systems | Managing for a Changing Climate. https://youtu.be/GdQztkUHJ30. YouTube. Video. Retrieved April 7, 2022.