If not for the Endangered Species Act, the Devils Hole pupfish might not exist anymore.

The tiny blue fish, found only in Nevada’s Ash Meadows National Wildlife Refuge, has struggled to keep its population over 100, but the Endangered Species Act has swooped in to protect it on more than one occasion.

But environmental advocates worry that the law — which helped save other American species like the bald eagle and grizzly bear — is going to lose its teeth. They’re concerned that weakened protections could hurt other species in Nevada too, like desert tortoises, the greater sage-grouse and the Dixie Valley toad, among others.

President Donald Trump’s administration last week announced sweeping changes to the nearly 50-year-old law’s implementation that would weaken protections for threatened species and make it easier to strip species of their endangered listing.

“It’s very shortsighted to think that we understand everything well enough to know we can let something like the Devils Hole pupfish wink out and think that means nothing to us,” said Jim Moore, a former desert ecologist with the Nature Conservancy in Nevada who’s now retired.

The changes, which will become effective next month, will also make it more difficult to consider how climate change could impact wildlife by allowing the government discretion in defining the term “foreseeable future,” opening the door for regulators to overlook threats related to global warming, according to the New York Times.

“This is the most significant attack on the Endangered Species Act in history,” said Patrick Donnelly, the Nevada state director with the advocacy group Center for Biological Diversity. “Trump is tearing away the very fabric of our bedrock environmental law.”

Already, the changes are facing legal pushback. On Wednesday, Earthjustice filed a lawsuit on behalf of several environmental and animal protection groups, including the Center for Biological Diversity. The suit claims the new rules “violate the language and purpose of the Endangered Species Act on multiple counts,” and that the administration failed to make the changes available for public comment, according to a news release.

The administration is defending the changes. Molly Block, press secretary for the U.S. Department of the Interior, said the department is “updating implementation of the ESA to make it more clear and consistent and to better work to address the conservation challenges of the 21st century.”

‘Our fate is intertwined’

The Devils Hole pupfish was listed as endangered in 1967 under the Endangered Species Preservation Act, the predecessor to the current Endangered Species Act, which was enacted in 1973. Though its population began to mysteriously decline in the 1990s, last year scientists counted 187 fish, a 15-year high.

But it is just one of several species in Nevada that environmentalists say have benefited from the Endangered Species Act’s protections — and stands to lose if those protections deteriorate. Many point to the desert tortoise, which has struggled with habitat loss, as another example.

Moore worked on a project in the 1990s to develop a habitat conservation plan for the tortoise. Those plans, part of the Endangered Species Act, essentially allow development in one area of an animal’s habitat in exchange for a higher level of protection elsewhere.

Without the law, Moore said, a plan to save the tortoise’s habitat wouldn’t have stood a chance against development.

Donnelly says he is also concerned for those species teetering on the edge of protection. The greater sage-grouse has already been a source of contention between environmentalists and the energy industry. The U.S. Fish & Wildlife Service is reviewing its listing next year.

In total, there are 30 species of animals and plants that live in Nevada listed as either threatened, endangered or a candidate for protection, according to the Nevada Fish & Wildlife Office.

Andy Maggi, executive director of the Nevada Conservation League and Education Fund, said removing climate change as a potential consideration for whether or not a species should be listed is essentially, “ignoring the biggest threat to species and habitat that exists in the world today.”

In further altering how the Endangered Species Act is implemented, the Trump administration has removed the language that directs officials to make their decision on a species’ listing “without reference to possible economic or other impacts of such determination.”

In her emailed statement, Block said the Department of the Interior has been clear that it will continue to make listing determinations “solely on the basis of the best available scientific information and without consideration for the economic impacts,” and that allowing economic impact analysis is “purely for increased transparency.”

But environmentalists and lawmakers alike see the change as benefiting private industries.

“By changing habitat protection standards, the Administration is making it even easier for private industry to damage critical habitats, specifically in Nevada,” Rep. Steven Horsford (D) said in an emailed statement.

Democratic Rep. Dina Titus, as well as Democratic Sens. Jacky Rosen and Catherine Cortez Masto, similarly disparaged the changes to the Endangered Species Act.

“Donald Trump and Richard Nixon have a lot in common, but at least Nixon listened to scientists and conservationists when he signed the Endangered Species Act into law,” Titus said in an emailed statement.

Rosen pointed out in a statement that the Endangered Species Act has saved numerous species from extinction, adding, “We must stand up and protect wildlife for our well-being and for future generations.

In a tweet, Cortez Masto accused Trump of “gutting” the landmark conservation law.

Environmentalists agree that the loss of one species, no matter how small, is a detriment to the entire ecosystem. The pupfish has been isolated for between 10,000 and 20,000 years, and, Donnelly said, there is still much to learn from it.

“Our fate is intertwined with that of endangered species,” he said. “If they go, that means something is fundamentally wrong.”