New, more realistic approach improves predictions of how climate will affect fish habitat in streams

New techniques for modeling water temperatures have allowed U.S. Geological Survey (USGS) scientists to better predict how climate change will affect the streams that are home to fish species like brook trout, according to a recent study.

Climate change is expected to bring warmer air temperatures to the Chesapeake region over the next several decades. And as air temperatures rise, water temperatures will also increase, threatening fish species like brook trout that are particularly sensitive to warming waters. Previous modeling has assumed water temperatures in rivers and streams would rise in a uniform manner, failing to account for the effect that cool groundwater has on warmer surface water.

“One thing that has been missing from other models is the recognition that groundwater moderates the temperature of headwater streams," said Nathaniel Hitt, coauthor of the study. "Our paper helps to bring the effects of groundwater into climate change forecasts for fish habitat." Accounting for the effects of groundwater will allow for better predictions of brook trout habitat loss, as well as more targeted approaches for habitat protection.

Species like brook trout are an essential part of headwater stream ecosystems, an important part of the watershed’s heritage and a valuable recreation resource. Chesapeake Bay Program partners committed to restoring and sustaining brook trout populations as part of the Chesapeake Bay Watershed Agreement.

The article, “Accounting for groundwater in stream fish thermal habitat responses to climate change,” is available online.