Important South Florida reefs buried during port expansion.

Muddy sediment stirred up by dredging and subsequent disposal has been linked to coral dieoffs in the MIami channel entrance area.

Well before the Panama Canal expansion project (New Panamax) was completed in 2016, the Port of Miami and Ft. Lauderdale’s Port Everglades were identified as prime destinations for new-age “mega ships.”

PortMiami was the first U.S. Atlantic port on the list, and it was determined that the entrance and the turning basin of the port would have to be dredged deeper by over 8 feet to allow ships with 200-foot beams and drafts up to 50 feet to deliver the goods. The dredging site comprised Government Cut between Miami Beach and Fisher Island, approximately 2 miles into the Atlantic Ocean. The dredge was to deepen the 44-foot-deep channel to 52 feet, and widen the entrance area to as much as 800 feet. Hanging in the balance is two living reef systems— Outer Reef and Middle Reef—plus other live hard-bottom that supports various corals and other sea life.

But this supposed economic boost proved to be the ecological blow many had feared. Despite promises to minimize the environmental impacts of five different dredges removing and transferring over 5 million cubic yards of bottom sediments offshore to dump sites, the U.S. Army Corps (ACOE) and contractors made a series of blunders that buried coral reefs and prompted the filing of a lawsuit in October of 2014 by the Miami Waterkeeper and co-plaintiffs Miami-Dade Reef Guard Association, Tropical Audubon Society and Miami-Dade resident Capt. Dan Kipnis.

Vessels associated with dredging work to accommodate larger ships at PortMiami.

The legal action was brought against ACOE under the Endangered Species Act. It is now verified that hundreds of thousands of threatened staghorn, elkhorn and other corals and live bottom were buried and killed by an asphyxiating blanket of dredged sediment, over 250 acres of critical reef habitat at the port entrance channel. National Marine Fisheries Service divers who surveyed the tract concluded that once sediments are removed, it will take several years before the species richness, densities and size class distributions comprising a healthy reef community are reached. These are the same reefs that protect Miami Beach’s imperiled coastline from storm surges and support teeming fish populations.

“The National Marine Fisheries Service (NMFS) is the federal agency charged with protecting our reefs,” said Miami Waterkeeper Rachel Silverstein. “The damage that the Army Corps of Engineers and its contractor, Great Lakes Dredge and Dock, have inflicted on our reefs is neither temporary nor insignificant, contrary to the Corps’ repeated assertions. They greatly exceeded expected levels of environmental harm to a reef tract they know is already stressed by diseases and rising ocean water temperatures.”

Silverstein claims the Corps failed to mitigate the negative effects of dredging and simply did not safeguard the only coral reef tract in the continental United States.

“Its contractor cut corners at every turn. They allowed transport ships to leak sediment plumes that basically strangled our reefs. They failed to provide sediment curtains to control turbidity. They refused to replace ineffective monitoring devices, and ignored survey data that indicated beyond doubt that the reefs were dying,” said Silverstein. “They basically cast aside the suggestions of local, state and federal experts to minimize the impacts, and now Miami-Dade County and its taxpayers, not the Corps, will ultimately bear the burden of paying for the reef’s repair.”

Corals buried in sediment have been severely compromised. There is also growing concern that seagrasses in nearby Biscayne Bay are suffering a similar fate, related to disposal of dredging byproducts.

According to Silverstein, the Corps finally agreed to pay NMFS more than $400,000 to relocate several hundred staghorn and elkhorn corals from the dredging site during the operation to a secure nursery run by the University of Miami. These corals are listed as threatened. However, when NMFS divers arrived on site, the Corps’ contractor had anchored the dredge ship directly atop the reef, preventing the divers from accessing most of the threatened corals. Despite repeated pleas from NMFS, the Corps refused to move its ship, even for one day, claiming the diversion would be too costly. Luckily, the dredge ship suffered a malfunction that required it to leave the reef for repairs, giving divers a short window to rescue a fraction of the threatened species, which survived at a University of Miami coral nursery.


Despite the logistical failures and loss of marine life from the dredging, the Corps has announced that they must come back to PortMiami to dredge again because they did not dredge the channel deep enough. And, they have set their sights on the Port Everglades project, though now face a delay due to another lawsuit over the documented damage at Miami.

“The damage in PortMiami has yet to be rectified,” said Silverstein, but that may be a silver lining for Port Everglades. We have already sued again over the Corps’ pre-project Environmental Impact Statement because it made no mention of the mistakes made at PortMiami. They must acknowledge that the reefs adjacent to Port Everglades have even greater coral density than the reefs off Miami. We simply cannot see a repeat of the devastation.”

Before the Corps gets a green light to proceed there, Broward County and the state should insist on more effective monitoring plans, more frequent underwater surveys and more accurate estimates of the anticipated damage.

For now, the $375 million Port Everglades project is put on hold while the Corps re-examines potential environmental damages. The delay came after environmental groups filed a lawsuit in 2016, citing damage at PortMiami. Though the public comment period is now closed on the Corps Port Everglades plan (over 10,000 comments were received) anglers and divers can follow the process by visiting for newsletter updates.

Direct Fisheries Impacts

It can be said that as the coral goes, the fishing goes. Numerous reef species rank among the top table fish for both recreational and commercial harvest. Forage for snappers and grouper, hogfish, spiny lobster and other species depend on healthy reefs and the supportive live hard-bottom nearby.

University of Miami’s coral biologist Andrew Baker, whose team rescued over a thousand coral colonies during the dredging, hopes that the mistakes in Miami will force dredge contractors to drain water from sediment-loaded transfer scows much farther from shore instead of over the reefs to prevent the burying of coral.

While the staghorn and elkhorn corals get all the press, it is the red-encrusting coralline algae, cut off from sunlight under sediment, that feeds the essential urchins, mollusks and smaller forage fishes that larger fish depend on. Pelagic species use the reefs as feeding stations, too, attracted by baitfish schools that orient to nearshore reef bottom. Factor in South Florida’s world-class diving and it becomes quite apparent that burying this ecosystem with dredge sediment must be minimized if not prevented.

Anglers have questioned how such massive dredging operations—lasting for years in many cases—affect the spawning aggregations of snook that gather in the South Florida port channels, and numerous bottom species that spend part of their life cycles there.

North Biscayne Bay, a stone’s throw from the Port, has suffered major seagrass loss over the past three years. Everything from Miami Beach storm runoff to sewage spills has been blamed but there is growing concern that the dredged sediment from the port may have a play in it. The Corps and its contractor transferred tons of the port dredge sediment to old, deep “borrow holes” in North Bay in a mitigation effort, to create substrate for seagrass to grow. The jury is out, but it’s not hard to imagine that the increased turbidity created by the dumping of channel bottom sediment has exacerbated the situation, adding to the bay’s seagrass die off. FS

Florida Sportsman Magazine November 2019

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