PortMiami Dredging Killed a Half-Million Corals, New Study Shows

PortMiami Dredging Killed a Half-Million Corals, New Study Shows
Florida Fish and Wildlife Conservation Commission
Coral reefs are more than just unique, irreplaceable ecosystems full of the Earth's natural wonders: Studies show they also act as natural storm-surge barriers that help break up gigantic waves before they steamroll over cities such as Miami. A recent study says Florida's reefs protect at least $1.6 billion in real estate. The cruise industry, meanwhile, sends a collection of booze- and trash-filled ships onto the ocean so the world's least interesting people can listen to Jimmy Buffett, barf, and pretend to enjoy the company of their spouses for a few days at a time.

Unfortunately, Miami's coral reefs appear to be suffering in order to prop up South Florida's puke-flotilla industry. According to a new peer-reviewed study from the Miami Waterkeeper in the journal Marine Pollution Bulletin, dredging projects at PortMiami killed a half-million corals between 2013 and 2015, when the port was widened.

The researchers — including scientists from the University of South Florida, the Shedd Aquarium in Chicago, and the University of Miami — say people monitoring corals near PortMiami had previously blamed coral deaths from that period on a disease outbreak. But upon further analysis, the Miami Waterkeeper's research team says it seems far likelier that dredging projects killed the corals. For one, some corals died despite not being susceptible to the diseases circulating during that time. Plus, corals closer to the dredging projects died in greater numbers than those that were farther away.

"It was important to differentiate these multiple impacts occurring on the reefs to understand the direct effects of dredging specifically," Dr. Ross Cunning, a research biologist at the Shedd Aquarium, says in a media release. "We brought together all the available data from satellites, sediment traps, and hundreds of underwater surveys. Together, the multiple, independent datasets clearly show that dredging caused the major damages observed on these reefs."

The researchers also unearthed more evidence that the dredging hurt the reefs. The underwater digging projects created plumes of sediment so large they could be seen from outer space. And, the scientists say, satellite images of the underwater clouds matched closely with maps of corals that later died.
click to enlarge A ruler shows seawhips buried in seven centimeters of fine sediment near the PortMiami shipping channel during dredging. Seawhips, like corals, must anchor to hard exposed rock and cannot live buried in sediment. - PHOTO BY MIAMI WATERKEEPER
A ruler shows seawhips buried in seven centimeters of fine sediment near the PortMiami shipping channel during dredging. Seawhips, like corals, must anchor to hard exposed rock and cannot live buried in sediment.
photo by Miami Waterkeeper
Miami Waterkeeper has been battling the U.S. Army Corps of Engineers for years over the dredging project. The Army Corps initially monitored corals within 150 feet of the dredging projects, but in 2014, researchers warned that clouds of sediment were traveling much farther than the Corps initially expected. The National Oceanic and Atmospheric Association then sent divers to try to transplant as many corals as possible, but not all of them could be saved. By the end of the project, more than 81 percent of the reefs were covered in sediment. Large swaths of endangered staghorn coral died.

Environmentalists have warned for decades that Florida's offshore corals are rapidly dying and will be nearly impossible to replace. Climate change and pollution already threaten them — the seas are not only warming but also absorbing unprecedented levels of carbon dioxide and becoming more acidic. These two factors have sparked mass coral-bleaching events around the globe. (Corals — invertebrate animals that can eat, poop, and reproduce — get their color from algae that live symbiotically inside their tissues. When corals become stressed, they expel the algae and turn white.)

In 2016, Philippe Cousteau Jr., the grandson of famous underwater explorer Jacques Cousteau, traveled to Fort Lauderdale to raise awareness about mass-bleaching events at Port Everglades near Fort Lauderdale. At the time, the Army Corps was trying to dredge Port Everglades using similar techniques, and Cousteau and others worried the project would kill off even more sections of Florida's offshore reefs. Environmentalists later sued the Army Corps and temporarily halted the project.

According to Miami Waterkeeper, Florida's offshore reefs — the only near-shore reef in the continental United States — have declined 70 percent since the 1970s. The scientists warn that, given the dangers corals already face from climate change, local and federal governments should be doing everything possible to protect the reefs, as opposed to hurting them further through construction projects.

"This study provides a clear and scientifically robust estimate of the impact of this dredging project on Miami’s coral reef resources. It tells a devastating story of loss that we cannot afford to ignore any longer," Rachel Silverstein, the executive director of Miami Waterkeeper, says. "We hope that these findings will provide valuable information to guide restoration of the impacted reefs and prevent these kinds of impacts in the future."
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Jerry Iannelli is a former staff writer for Miami New Times from 2015 to March 2020. He graduated with honors from Temple University. He then earned a master's degree in journalism from Columbia University.