The bustling streets and luxurious lifestyles of Miami-Dade County in South Florida often overshadow a secret world that exists beneath its surface—a world inhabited by a remarkable, little-known creature: the Miami cave crayfish.

This unassuming, lobster-like crustacean resides deep underground in the porous limestone rock of the Biscayne Aquifer, a crucial source of drinking water for millions of residents, according to the Florida Department of Environmental Protection. But today, the Miami cave crayfish (Procambarus milleri) is facing a dire threat—the rising seas and tides brought about by climate change.

As the sea level steadily creeps higher, salty water is infiltrating the subterranean cavities of the Biscayne Aquifer, jeopardizing not only the crayfish but also the freshwater supply that sustains both human life and biodiversity. In response to these alarming developments, the U.S. Fish and Wildlife Service (FWS) has proposed listing the Miami cave crayfish as a threatened species under the Endangered Species Act. This move is not only an attempt to safeguard this unique species but also to protect the vital drinking water source on which millions of Florida residents depend.

Photo: Wikimedia Commons / Adam G. Stern, License: CC BY-SA 4.0 DEED
The Miami cave crayfish, scientifically known as Procambarus milleri, is a unique and little-known crustacean species.
The Miami cave crayfish, scientifically known as Procambarus milleri, is a unique and little-known crustacean species.

An Enigmatic Resident of the Depths

The Miami cave crayfish remains shrouded in mystery, even for scientists. These crustaceans are rarely seen in their natural habitat due to their subterranean lifestyle. The cave crayfish has a shell a little over an inch long, and descriptions from those fortunate enough to encounter them describe them as pale and colorless. While it might not be a common sight, these cave crayfish occasionally find themselves in the world above when they are unintentionally drawn into pump systems connected to freshwater wells.

The initial discovery of this elusive species occurred in 1968 when a cave crayfish was found deceased in a 22-foot-deep well, reports the Miami Wire. Unfortunately, sightings remained scarce, with the next one reported in 1992 when an individual was accidentally captured in an aquarium tank at a fish farm in Homestead. Since then, only around 50 confirmed sightings have been recorded, with the most recent occurring during a study funded by the FWS in 2018.

Photo: Wikimedia Commons / Adam G. Stern, License: CC BY-SA 4.0 DEED
These crayfish are native to the underground limestone rock formations of the Biscayne Aquifer in Miami-Dade County, Florida.

The Crayfish as a Climate Change Indicator

The crayfish's subterranean habitat, though hidden from view, plays a vital role in maintaining the delicate balance of the local ecosystem. As the Miami Herald reports, their unique lifestyle and habitat make them an important indicator of environmental changes, particularly those associated with climate change and sea level rise.

The proposed listing of this species as threatened by the FWS reflects the urgency of addressing these issues.

“This is just one of many species in Florida that’s really imminently threatened because of climate change and sea level rise,” Elise Bennett, the senior attorney at The Center of Biological Diversity, told the Miami Herald. “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.”

Photo: Wikimedia Commons / United States Geological Survey, License: Public Domain
Rising sea levels and saltwater intrusion are posing substantial risks to both the crayfish and the Biscayne Aquifer.

A Fragile Aquatic Ecosystem at Risk

The fate of the Miami cave crayfish is closely intertwined with the health of the Biscayne Aquifer. Unfortunately, this critical aquifer is under siege from multiple fronts.

As global sea levels rise, saltwater intrusion poses a significant threat to the freshwater found within the aquifer. Experts predict that sea levels will rise by about a foot globally by mid-century, with even greater increases along the U.S. East Coast and Gulf Coast. A study published by Tufts University explains how this rise allows saltwater to infiltrate the aquifer from below and can also affect Miami-Dade's canals, further endangering freshwater resources.

While the majority of the crayfish's habitat has not yet been impacted by saltwater intrusion, some areas within the aquifer are already showing signs of increased salinity. This is particularly concerning for a species that relies on freshwater for its survival.

Multiple Threats Compound the Crisis

Climate-driven sea level rise is not the sole threat to the Miami cave crayfish and the Biscayne Aquifer. Rising temperatures, expanding populations, and increasing water demands are compounding the problem. With a growing population and higher temperatures, the aquifer is being depleted, allowing saltier and brackish water to encroach from the coast, Miami Dade County reports. The FWS estimates that the aquifer has already shrunk by approximately 11%.

Furthermore, threats to water quality and habitat from urban development and pollution are becoming increasingly pressing concerns. Degradation of water quality, contaminants, and reduced food supply could further jeopardize the crayfish and other aquatic species.

Photo: Pexels
The fate of the Miami cave crayfish is closely intertwined with the health of Miami's Biscayne Aquifer.

Conservation Efforts and the Road Ahead

The journey to protect the Miami cave crayfish has been a protracted one, with the species waiting for federal regulators to draft protection plans for far too many years.

“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 told the Miami Herald.

The proposed listing of the Miami cave crayfish as a threatened species under the Endangered Species Act is a critical step toward achieving this goal. It is a call to action—a call to protect the hidden treasures that lie beneath our feet and the life-giving freshwater that sustains us all. It is a call to safeguard the Miami cave crayfish and the future of Miami-Dade County's water supply.

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