Scientists are exploring mysterious “blue holes” that form at the bottom of the ocean off Florida’s Gulf Coast.
The blue holes are underwater sinkholes that vary in size, similar to sinkholes you can see on land, according to the National Oceanic and Atmospheric Administration. They are diverse biological communities full of marine life, like corals, sponges, mollusks, sea turtles, sharks, and more.
“Underwater sink holes, springs, and caverns are karst (calcium carbonate rock) features that are scattered across Florida’s Gulf continental shelf,” said NOAA.
NOAA says little is known about blue holes due to their lack of accessibility and unknown distribution and abundance. Openings can be several hundred feet underwater and many openings are pretty small.
“In fact, the first reports of blue holes did not come from scientists or researchers, but actually came from fishermen and recreational divers,” wrote NOAA.
Last year, a team of scientists explored one blue hole, called “Amberjack Hole,” about 30 miles off Sarasota’s shoreline. NOAA says the exploration of the hole was the team’s most detailed blue hole investigation to date. Divers and a “benthic lander” were deployed to the bottom, 350 feet down.
NOAA says the team collected 17 water samples from just outside the hole down to the bottom and collected four sediment cores at the bottom. They also discovered two dead but intact smalltooth sawfish, an endangered species, at the bottom of the hole. One of the animals was recovered to undergo a necropsy.
But next month, crews plan to explore an even bigger hole, called “Green Banana.”
The rim of the “Green Banana” is 155 feet below the sea surface and the bottom is at a depth of approximately 425 feet, according to NOAA.
“The configuration of the hole is somewhat hourglass shaped, creating new challenges for the lander deployment and water sampling,” said NOAA.
From these missions, scientists are hoping to learn the following:
- Whether the submersed sinkholes are connected to Florida’s groundwater or if there is groundwater intrusion into the Gulf of Mexico
- If a particular blue hole is secreting nutrients and thus affecting an area’s primary production
- Whether microenvironments harbor unique or new species of microbes
- If the Amberjack site should become a protected area