On a late November morning, Florida Tech marine biologist Robert van Woesik and several of his students are aboard a 25-foot dive boat, speeding several miles east of Key Largo to the site of an underwater coral nursery.
Wrapped tightly in wet suits, they wriggle into weight belts, adjust their air tanks and buoyancy vests and lower their goggles. Each diver pops a regulator into their mouth and slip overboard into the warm, blue seas. Slowly they descend 60 feet to their underwater research coral reef site.
The divers are conducting routine maintenance in offshore coral tree nurseries where staghorn coral hang on dozens of towering man-made racks. In the crystal clear water the views are stunning, as a beefy grouper, parrotfish and amberjack flash by. The divers are recording data on a special waterproof tablet of the growth and mortality of previously out-planted corals on the man-made trees. On other reefs, they take measurements to determine how much live reef tissue remains and if the coral has been bleached or are suffering from disease.
Coral reefs are among the greatest natural wonders of the world. Their beauty is a powerful attraction for local residents and the masses of vacationers who visit Florida in order to enjoy scuba diving and snorkeling, marveling at the coral’s bright colors, sculptural shapes, and stunning diversity.
Although coral reefs occupy less than one percent of the world’s ocean floor, they are one of the most biologically diverse ecosystems on Earth. The largest living structures on the planet, coral reefs are large calcium carbonate structures, built by colonies of tiny marine animals called corals. It’s reported that nearly a third of all marine life— fish, invertebrates such as jellyfish, and sea mammals—live there. Large calcium carbonate structures, the reefs are the foundation of and home to a myriad of other species and the only living structure visible from the moon.
However, their beauty is fading fast. The coral reefs have experienced unprecedented declines over the past three decades due to ocean warming and other stressors that cause the phenomenon of bleaching where eventually the reef will die.
“It’s a shock to their system, it’s hard for them to adapt,” said van Woesik, a certified marine ecologist. “We’re seeing some very tough times. With the rising ocean temperatures the reefs bleach and don’t survive.”
Prior to arriving at Florida Tech in 2002, van Woesik earned his Ph.D. on studying the Great Barrier Reef and worked at the Australian Institute of Marine Science in Queensland, and was an Assistant then Associate Professor at University of the Ryukyus, Okinawa, Japan where he worked for eight years.
“Twenty years ago I would never have thought this type of research was necessary,” said van Woesik, a native of northern Brisbane, Australia. “With so many reefs under threat, our mission is to understand where farmed corals will survive, and under which conditions.”
Stretching 150 miles long and four miles wide, extending to the edge of the Florida Straits, the Florida Reef tract is the third largest barrier reef ecosystem in the world. There are plenty of options as to where on the reef tract to place those new corals. With a $205,000 grant from the FWC, van Woesik and his team of FIT students will be identifying habitats and localities in the tract that are best for coral survival.
Fish and Wildlife Conservation Commission (FWC) scientists are collaborating with numerous partners on a regional coral restoration effort by transplanting healthy nursery-grown corals back onto the reefs. Coral reefs are often called the rain forests of the sea, due to the vast amount of species they both harbor. The reefs provide spawning, nursery, refuge and feeding areas for a large variety of organisms, including sponges, crustaceans (shrimp, spiny lobsters and crabs), starfish, sea urchins and sea turtles. The structures also play an important role as natural buffers, minimizing wave impacts from storms and protecting nearby villages from sea-level rise. Hurricanes can devastate an entire coral reef section within a few hours, just as fire can ravage a forest.
Sadly, since the 1970s, the populations of two key reef building species— staghorn and elkhorn coral— have declined by 92–97% according to The Nature Conservancy. Beyond ocean warming, other factors damage coral reefs including physical damage from anchors, boat groundings, lobster traps, as well as polluted water and runoff from shore.
There are 13 man-made coral nurseries in Florida waters, and the Key Largo-based Coral Restoration Foundation oversees three of them. These nurseries grow tens of thousands of staghorn corals, which then are transplanted to impoverished reefs in Florida. Within a few years these new coral growths are spawning and adding new life. In fact in 2016, many of the corals at the nurseries spawned before they were even transferred to the reefs.
Nearly 10,000 colonies have been reestablished on reefs since 2004, with first-year survival rates for these corals averaging above 80 percent according to The Nature Conservancy. Second-year survival is considerably lower.
“The artificial coral trees are made of a PVC pipe about five feet in length, anchored to the ocean’s floor,” said van Woesik. Horizontal extensions support the small corals. We will be studying factors such as temperature and water-flow rates in the hope that the corals grown at the nurseries will have better survival rates when they are transplanted to the reefs.
“The coral trees are raised up off the ocean floor so that the new coral gets a strong current passing over them. With that high water flow, they grow incredibly fast.”
Healthy coral reefs provide benefits to both marine life and people.
“We’re looking for both the strongest corals, and the best place to plant them on the reef” van Woesik said. “It’s all about speeding up the recovery process.”