More Than Half a Million Corals Died to Bring Bigger Ships Into Miami Port

All these corals died near the Port of Miami—all to expand the channel and allow in bigger ships.
All these corals died near the Port of Miami—all to expand the channel and allow in bigger ships.
Photo: Getty

Off the coast of Miami, corals are dying. Why? Because of a 16-month-long project to expand the harbor channel. A new study shows how the project killed over half a million corals between 2013 and 2015.


Published in the journal Marine Pollution Bulletin Thursday, the study involved on-the-ground observations of the corals coupled with satellite images to see how much sedimentation the project’s dredging threw into the water—and how all that sediment ultimately affected coral health. The authors found that nearly 2,000 pounds of sediment were suffocating the reefs for every 10 square feet about a mile and a half out from where the dredging was occurring.

As the authors found, up to 74 percent of corals died near the channel in the months after the dredging to expand the shipping channel began. Even two years later, the researchers found that the density of corals some 65 feet from the channel had suffered as a result of the sedimentation.

Corals are pretty fragile organisms. If the water grows too warm, they can begin to die as they expel the algae they need to help produce food. Too much acid in the water (as a result of carbon dioxide), and corals grow weaker and can shrink. Now, if sand and sediment pile on top of corals, they lose access to light, which helps their algae produce food, and they can use a lot of energy trying to remove all that sediment. In short, all these things can kill corals, which are already dying around the world in mass due to climate change.

“If we want to conserve these ecosystems for the generations that come after us, it’s essential that we do all we can to conserve the corals we still have left,” said senior author Andrew Baker, an associate professor of marine biology and ecology at the University of Miami, in an academic release. “These climate survivors may hold the key to understanding how some corals can survive global changes.”

In Miami, more than 560,000 corals were killed in the immediate vicinity of the dredging, according to the study. The authors were able to look at where the sediment plumes hit via satellite images to estimate the distance of the impact. Turns out that they were likely felt more than six miles away from where the dredging occurred. Before the project began, only one coral had been tagged as partially buried by sediment. After the project, the reefs were completely transformed.

Sea whip coral buried under nearly 3 inches of sediment.
Sea whip coral buried under nearly 3 inches of sediment.
Photo: Miami Waterkeeper

An independent consulting firm that the Port of Miami and Army Corps of Engineers hired to conduct environmental monitoring for the project previously attributed the mass coral die off to a disease outbreak. This study, however, controlled for that and looked at how corals closest to the dredging fared during this period. The study’s results contradict what the consulting firm found and showed the value of using satellite images, on-site observations, as well as sediment data, to find the root cause of what’s harming coral.


“It was important to differentiate these multiple impacts occurring on the reefs to understand the direct effects of dredging specifically,” said lead author Ross Cunning, a research biologist at the Shedd Aquarium in Chicago, in the 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 results are heartbreaking: The threatened staghorn coral, which is protected under the Endangered Species Act, was one of those affected. So is elkhorn coral, another threatened species. These corals need all the protection they can get. And development projects that kill them certainly don’t help the threats they already face from warming oceans.


Yessenia Funes is climate editor at Atmos Magazine. She loves Earther forever.


Dense non aqueous phase liquid

Nonprofits like the Shed, if they’re going to add value, should probably get out in front of a project when it’s it’s in the mind’s eye or at least on paper. This would be somewhere between early site characterization/investigation studies and feasibility study. Maybe get up-to-speed on proactive environmental investigation work during early phase project delivery at a Chicago Sanitation and Ship Canal or a Indiana Harbor dredging project, should there be one.

It appears that the Port and USACE environmental consultant was brought onboard for construction monitoring. That’s pretty far down the line and usually defined, as Yessenia mentions. And we’re talking the Port of Miami here. It ain’t no Port Authority of New York/New Jersey.

The fact of the matter is Trump admin is speeding up project delivery where the fed is involved, especially for oil and gas infrastructure like pipelines going towards coastal LNG plants and export facilities and the facilities themselves. This will give Shed a lot of after-the-fact opportunities.

Shed should read Fed Biz ops dot gov to time their next study. All the project phases below, should they be contracted, would be listed. Get in at the study phase. Shed could ask to be a third party environmental study group participating out of public spiritedness. A stakeholder if you will. That should go well with two parties on a fast track.

Water Resources Project Delivery

Request for Federal Engagement

Study Initiation Phase

1: Initial Problem Identification

2: Congressional Study Authority

3: Letter of Intent from Sponsor

4: Congress Appropriates Study Funds


5: Execute Feasibility Cost Share Agreement and Secure Sponsor Study Funding

6: Scope and Conduct Study

7: Release Draft Feasibility Report for Concurrent Review

8: Complete Final Feasibility Report for Coordination and Submission

9: Policy Review of Final Feasibility Report

10: Federal and State Agency Review

11: Sign Chief of Engineer’s Report

12: Administration Review of Chief of Engineer’s Report

Pre-Construction Engineering and Design (PED)

13: Congress Appropriates PED Funds

14: Execute Design Agreement and Secure Sponsor Design Funding

15: Conduct Pre-construction Engineering and Design activities


16: Congress Authorizes Project

17: Congress Appropriates Construction Funds

18: Execute Project Partnership Agreement and Secure Sponsor Construction Funding

19: Implement Project

Operation and Maintenance

20: Operation, Maintenance, Repair, Replacement and Rehabilitation