NOAA Leads Project to Restore a Seagrass Meadow in Florida Keys National Marine Sanctuary

By Scott Atwell

April 2025

This Earth Day, NOAA’s Florida Keys National Marine Sanctuary is overseeing a project to restore a damaged seagrass meadow in the Northwest Ship Channel off Key West, where a ferry boat damaged a large section of the seafloor after running aground. The restoration project is expected to last into June.

an aerial view of the ocean with the seafloor visible. A sandy area is surrounded by seagrass. — Aerial view of the seagrass restoration area showing a large sandy patch in the middle of a seagrass bed that was damaged in 2016 during a vessel incident. Photo: U.S. Coast Guard, Sector Key West

a sandy patch in the middle of a seagrass bed with stakes that rise above the water’s surface — PVC stakes were used to delineate the edges of the blowholes for placement of the pea rock and sediment tubes. Photo: Lisa Symons/NOAA

The ferry boat incident occurred in December of 2016, and the owner agreed to a financial settlement four years later. COVID-19 delayed project planning for the restoration project, and over time the damaged area expanded laterally, even while becoming more shallow. The exposed area will be rehabilitated by filling the blow holes with up to 100 yards of pea gravel, and then laying out 14,000 sediment tubes, which are cotton bags filled with a mix of sand and gravel. Almost 2,000 planting units, consisting of two to three seagrass shoots harvested from nearby donor beds, will be inserted into the tubes, along with fertilizer spikes.

Several white cotton sand bags stacked on top of one another on a beach near a boat yard. — 14,000 sediment tubes were prepared to fill in the blow holes of the project area. Photo: Sea & Shoreline

a drawing that depicts, a sandy area surrounded by seagrass that is filled in with sandbags, seagrass plugs, and stakes — Planting units are placed over fill material to provide a substrate for the seagrass shoots to take hold, and the planting units and fertilizer spikes are strategically placed to encourage seagrass growth. Image: Industrial Economics, Inc.

The fertilizer spikes will be replaced every 90 days for a year and half, providing the plants with additional phosphorus, the main limiting nutrient for seagrass growth in the carbonate sediments. The spikes are a specific formulation of phosphorus and nitrogen that promotes growth of seagrass and not the proliferation of macroalgae or harmful algae associated with red tide events. In waters with less current, NOAA and other partners can use bird stakes to increase the necessary nutrients for the seagrass.

Boaters will see a large barge and work boats at the site until late May or early June. "We would appreciate boaters in the area supporting the restoration by slowing down, so that the divers working on the project aren't swamped by wakes," said Lisa Symons, regional response coordinator for Florida Keys National Marine Sanctuary. “In addition, a contractor’s barge will be travelling from the work site to Stock Island every day for about four weeks.

Birds rest on poles above the water — Bird feces helps fertilize seagrass. Sticks are sometimes placed at areas where seagrass is being restored so that resting birds will "fertilize" their growth. Photo: NOAA

Serendipitously, the start of the restoration project coincides with Earth Day, which originated in 1970 to raise awareness about environmental issues. The Florida Keys ecosystem features 1.5 million acres of seagrass meadows, one of the world's largest contiguous seagrass habitats, important for queen conch, Bahama sea stars, manatees, green sea turtles, egrets, and other wildlife. When boaters do not follow responsible boating guidelines, this critical habitat, often in shallow water, is easily damaged by propellers and boat bottoms.

“All boaters can make an Earth Day commitment by pledging to keep their [boat] bottom off the bottom,” said Symons. “Never, ever try to power off if you run aground, regardless of what size vessel you are operating. Please wait for high tide and call a salvor for assistance. This limits the amount of injury to the corals, seagrasses, and to vessels.”

Florida Keys National Marine Sanctuary offers a free, voluntary boater education course that can help vessel operators recognize the challenges of operating in these waters.

Scott Atwell is the media coordinator for Florida Keys National Marine Sanctuary

Rachel Plunkett is the content manager and senior writer/editor for NOAA’s Office of National Marine Sanctuaries