A sure sign that an ocean reef is thriving is the sound of fish eating the coral. “A healthy reef is really loud. It’s deafening under water,” said Lindsay Eneguess ’11.
Depending on the number and variety of species, sea creatures noshing on the corals’ hard exoskeleton can sound like crunching on chalk or eating Grape Nuts without the milk.
Coral are animals. They secrete calcium carbonate, forming an exoskeleton, which builds the reef that creates an ecosystem for more than 25 percent of Earth’s marine species. But coral reefs cover less than 1 percent of the world’s ocean surfaces, so it’s important to know why so many are dying.
Hawksnest Bay, part of the Virgin Islands National Park on the island of St. John, is one of the places where reefs are in trouble. Eneguess, an environmental sciences and studio art major at Sweet Briar, spent a week there in June with a team of forensic investigators to help the National Park Service figure out why.
Eneguess is featured in the cover story of the Sweet Briar Magazine, published this month. The full text is available online.
Eneguess was interning for Sweet Briar research scientist Craig Downs, a coral reef expert who is working with scientists from the U.S. National Oceanic and Atmospheric Administration on the project.
During the summer Eneguess and Downs also dove in waters off the Florida Keys and in Guantanamo Bay, Cuba, where they collected coral, sediment and algae samples for a U.S. NOAA-led project.
Because the U.S. Navy restricts access to Guantanamo Bay, it is home to some of the world’s most pristine coral reefs. That makes it an ideal reference site for what healthy reefs should look and sound like. Eneguess was lucky to be able to dive there and joined the relatively few civilians allowed access to parts of the island and the naval base where they lodged and ate.
The summer internship entailed varied responsibilities from planning and logistics to testing sediment in the College’s laboratory, but the underwater forensics quickly became Eneguess’ favorite part.
First, there was the wildlife. “Seeing everything I’ve seen on National Geographic was really cool,” she said.
It also made her consider whether she wants to pursue field research after she graduates from Sweet Briar. As an athlete who has received all-conference honors in field hockey and a double major in studio art, science hasn’t always been her first love. Now she’s thinking about it.
At St. John, Eneguess and Downs made eight dives, including in areas of the bay that catch drainage from the surrounding jungle. They usually waded from the surf out to depths of 25 to 30 feet — which made it doubly exciting when Downs spotted a 9-foot bull shark swimming within 15 feet of his intern. He motioned to ascend and they were done diving for the day.
Downs was cautious because the bay was slightly cloudy from a recent rain, which occurs in marine waters fed by gullies or streams. Experienced divers usually avoid such conditions in waters known for really scary sharks, such as tigers and makos, he says.
“The turbidity and ‘flavor’ of the water drives sharks to be aggressive. This bully was circling us and throwing its head back and forth in an agitated manner. I’ve wrestled small bullies out of sea turtle nets by hand, in the water on snorkel, and never an issue. But this bully really looked like it was dangerous.”
They returned in a boat and chased the shark away the next day. Downs couldn’t help but notice it was towing two 3-foot remoras, a fish that hitches rides on other animals, traveling for free and sometimes snacking on their leftovers.