Rare clawed creature lives in Miami’s underground water supply. Can it survive sea rise?

BY ASHLEY MIZNAZI

U.S. Fish and Wildlife Service is moving to list the The Miami cave crayfish as threatened under the Endangered Species Act. The rare species biggest threat is the sea level rising. ADAM STERN

A little-known lobsterlike creature lurks deep under the homes and streets of coastal Miami-Dade County, swimming and feeding in the porous limestone rock that holds the drinking water supply for millions of residents.

It’s called the Miami cave crayfish, a rare and rarely seen crustacean whose future — like the underground freshwater where it lives — faces increasing threats from climate change as rising seas and tides push salty water deeper into the holes and cavities of the Biscayne Aquifer’s Swiss-cheeselike lime rock.

Now, the U.S. Fish and Wildlife Service is moving to list the tiny crayfish as threatened under the Endangered Species Act.

“Safeguarding the Miami cave crayfish and its freshwater habitat benefits us all,” said FWS regional director Mike Oetker in a release announcing the proposal. “Millions of Florida residents depend on the Biscayne Aquifer as a main source for drinking water — protecting it from saltwater intrusion is a win-win situation for people and wildlife.” 

There is still a lot of mystery surrounding the population and habits of the Miami cave crayfish. It has a shell about as long as paperclip and underground denizens have been described as pale and colorless. Because they live in bedrock and are difficult to spot in the wild, most of the research on them comes from aquarium studies. Most of those captive adult species are tangerine colored with a distinctive red stripe down its tail.

While you shouldn’t expect to see one come out of your faucet, the cave crayfish occasionally gets sucked into pump systems tapping freshwater wells. That’s how the first species was first discovered — dead in a 22-foot-deep well in 1968. According to the federal wildlife service, it wasn’t seen again until 1992 when one got sucked into an aquarium tank at a fish farm in Homestead. The crayfish is believed to live underground in about 16 locations along the Miami-Dade’s coastal ridge.

There had been only about 50 reported sightings since, most recently in 2018 during a FWS-funded study. At least until early Friday morning when Florida International University biology professor Philip Stoddard read the Miami Herald article on the crayfish. He grabbed a flashlight and went out into his South Miami backyard.

He’d first seen them in 2004 when he had a grotto dug down about seven feet into the limestone. In 2018, the FWS had put crayfish traps in his backyard for its study and caught a few. He stepped carefully into a shallow area before the sun came up Friday and spotted and photographed two swimming around.

“People don’t know where to look or have a way to look,” said Stoddard, an environmental advocate who is the city’s former mayor. “They come out and frolic, they’re there all the time. They’re frisky little guys. They dart away from the flashlight, and they’re only in the backyard in the dark.”

The Miami cave crayfish is a rarely seen crustacean that lives below ground in the Biscayne Aquifer. Adam Stern

A CLIMATE CHANGE INDICATOR

Though an obscure little creature, the crayfish is also an potentially important indicator of climate change threats.

“This is just one of many species in Florida that’s really imminently threatened because of climate change and sea level rise,” said Elise Bennett, the senior attorney at The Center of Biological Diversity, which first petitioned the FWS to protect it in 2010 and eventually sued the agency over it and other unlisted rare species. “So every time we see one of these listings, it should be a reminder that we need to be doing more to stop using fossil fuels to save these species but also to save ourselves.” 

Last week, the service proposed listing the Miami cave crayfish as threatened from a long list of more than 400 other aquatic species in the Southeast which also are in line to be classified as threatened or endangered.

The fate of the Miami cave crayfish is closely tied to the health of the underground Biscayne Aquifer, which stretches from the coastline into the Everglades and supplies much of the drinking water to Miami-Dade and the Florida Keys. The aquifer is also threatened by saltwater intrusion, as climate change raises water levels in the Atlantic Ocean, Biscayne Bay and Florida Bay.

Experts predict that sea levels will rise globally about a foot by mid-century, and slightly above that along the U.S. East Coast and Gulf Coast, according to the National Oceanic and Atmospheric Administration. As the sea level rises, the saltwater wedge creeps into the aquifer from underneath and also can find its way into Miami-Dade canals that crisscross the coastal ridge. Right now, most the crayfish habit hasn’t been hit by saltwater intrusion, but some areas of the aquifer do already show signs of salt water intrusion, said Emily Bauer, the lead biologist at FWS. That could be lethal for a species that lives in freshwater.

“It’s an indicator that freshwater is not going to be there for us when we need it,” Bennett said. “It really is a cautionary tale, that we need to get our arms around climate change and sea level rise and try to turn it around as best we can.”

Climate-driven sea rise isn’t the only threat to the crayfish and aquifer. As temperatures rise and the population grows, water demands increase and shrink the size of the aquifer, making room for salty and brackish water to push in from the coast. The FWS estimated the aquifer has declined about 11 percent in size already.

A map in the U.S. Fish and Wildlife Service species report shows estimated saltwater intrusion (red line) into the Biscayne Aquifer in Miami-Dade County as of 2018. The underground water supply also is the habitat for the rare Miami cave crayfish.

Other potential future threats to the crayfish include declining water quality and development, which can reduce the supply of decaying plants and micro-organisms that filter down from the surface for the crayfish to feast on.

“If the water quality gets too bad or if you get contaminants, or don’t have enough food, those are threats to aquatic animals everywhere,” said Larry Williams, the Florida FWS ecological services director. “But in all the information gathering that we did, we didn’t find any evidence of those things harming Miami cave crayfish.”

LONG ROAD AHEAD

Bennett, the Center for Biological Diversity attorney, said it should not have taken so many years for federal regulators to begin drafting protection plans for the Miami cave crayfish and other southeastern aquatic species. The risks only continue to grow, she said, even as populations decline.

“Our fear is that the longer these species wait, they’re either going to decline further and it’s going to be harder to save them, or they could even go extinct while they’re waiting for protection,” Bennett said.

But Williams of the FWS said the demand for protection plans outstrips the agency’s resources.

“One problem that we have is the number of species that we are petitioned to list is way above our staff capacity,” Williams said.

FWS said they have a draft proposal to protect the “critical habitat” of the Miami cave crayfish that they expect to post later this year after the Office of Management and Budget reviews it.

“If it was going to have an effect on, say, the regulation of that water supply, [the OMB] would want to analyze that in detail and understand it before that proposal goes out,” Williams said. “Our plan is to work with the Miami-Dade government and the South Florida Water Management District with the approach that as they’re managing the aquifer, they make sure that it stays at a healthy level.”

Now that there is a proposed rule to list the Miami cave crayfish as threatened, the public has until Nov. 6, 2023 to submit comments to the agency before the report is finalized. From there, FWS will work on a “blueprint to recovery” plan that’s likely to take another year.

Florida International University biology professor, Philip Stoddard, took photos this morning of two Miami cave crayfish swimming in his backyard grotto. Philip Stoddard