By saving ecosystems, environmental regulations help prevent biodiversity loss

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By saving ecosystems, environmental regulations help prevent biodiversity loss

Conservation policies associated with improved water quality, study finds

Long-term conservation policies may help restore freshwater ecosystems and prevent extreme species loss, new research suggests.

As emerging threats such as warming temperatures, pollution and other cumulative stressors put pressure on freshwater populations and contribute to global biodiversity crises, experts have sought to assess how effective environmental protections are at curbing this decline.

Now, researchers have revealed that long-term improvements in water quality, as well as the increased occurrence of certain aquatic species, are likely associated with the implementation of broad environmental regulations such as the Clean Air Act and the Clean Water Act.

"Rivers provide a lot of cultural, recreational and ecosystem services, and we also depend on fresh and clean water to survive," said Casey Pennock, senior author of the study and an assistant professor in the aquatic ecology laboratory at The Ohio State University. "That's really the motivation behind these conservation policies, to ensure that the natural environment is usable for both wildlife and all other things we care about."

Aside from negatively impacting local biodiversity, contaminated water can destroy fishing industries and damage human health. It's thanks to widespread environmental protections that water quality in the U.S. is better today than it was only a few decades ago, said Pennock. His team's newfound evidence for this claim stems from water quality and aquatic species data collected between 1970 and 2023 across seven major river basins in Ohio.

By using that data to analyze how fish, insects and freshwater mussel communities changed over time, the team's findings showed that lower levels of pollutants in rivers - such as zinc, ammonia and lead - corresponded to increases in range for many aquatic species. These findings suggest the affected groups were those with heightened sensitivity to poor water quality.

Their observations indicated that as water quality improved, 71 fish species and 171 insect groups became more common across the state of Ohio, large river basins, with only a few species decreasing. Freshwater mussels, however, experienced mixed responses over time, with nine species increasing and 10 decreasing in occurrence. The composition of fish, aquatic insects and freshwater mussels also changed significantly over time in all seven river basins researchers studied.

"Ecological communities are not static; they're dynamic systems," said Pennock. "Monitoring them is important to assessing how their trajectories change as new contaminants come online."

The study was recently published in the journal Ecological Indicators.

Despite how critical freshwater diversity is to the health of all of Earth's ecosystems, it can be difficult for people to link the issue of conservation to the benefits they reap from it - such as protection from infectious diseases and a safe drinking water supply - in their everyday lives, said Lindsey Bruckerhoff, a co-author of the study and an assistant professor in the aquatic ecology laboratory at Ohio State.

"Our work revolves around trying to prevent further declines of imperiled species and keep diversity on the landscape," she said. "So extensive research like this that highlights the positive effects of those systems on humans is incredibly rare."

Additionally, as a lack of broad-scale monitoring efforts has made it difficult for researchers to document species-specific responses to prolonged environmental changes, this study, which compiles observations from numerous archives, is a vital addition to future conservation efforts.

"We now have a dataset where we can actually analyze long-term biodiversity trends," said Bruckerhoff. "It's really exciting to be able to chart success in that way."

According to the study, implementing nationwide policies also motivates municipalities to upgrade their own conservation initiatives. In response to the Clean Water Act, for example, Columbus instituted a $200 million municipal wastewater upgrade initiative for the Scioto River, leading to significant declines in levels of ammonia and heavy metals that continue to decrease today.

Overall, their results suggest that policies that promote conservation gains for animals like fish and insects and, by extension, protect human health, should remain in place, the researchers say. These outcomes also provide evidence of the benefits derived from environmental regulations.

"This work shows there's still more work to do," said Pennock. "It tells us that if we deregulate or allow more pollution to happen, then those gains could reverse themselves, to our detriment."

This study was supported by the U.S. Fish and Wildlife Service and the Ohio Biodiversity Conservation Partnership. Other Ohio State co-authors include Seth Drake and Nathaniel Shoobs, as well as Robert Miltner from the Ohio Environmental Protection Agency.

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