MARTIN COUNTY — Standing in waist-deep water in the Indian River Lagoon, Martin County staff scattered 3.2 million tiny clams across the lagoon floor, hoping the shellfish can help restore the seagrass that has disappeared from large areas of the estuary.
The clams, donated by the Great Florida Shellfish Company, are part of a restoration effort that takes a different approach to the lagoon's declining seagrass beds.
"They look like quinoa blades, and then just buckets and buckets of them just scattered across the area. Then they kind of dig down into the substrate and start to do their thing," said Michael Yustin, a project manager with Martin County.
Rather than trying to replant seagrass across the lagoon, the county is testing whether improving the surrounding environment can help the grass grow back on its own.
"We didn't want to just go out and plant seagrass. First of all, I don't think you could plant your way out of this," Yustin said. "There's something like 60,000, 70,000 acres of seagrass habitat in the Indian River Lagoon. You're not going to be able to plant that much seagrass."
Seagrass in the lagoon has suffered significant declines, largely because of nutrient pollution. Excess nutrients fuel algae growth, which blocks the sunlight seagrass needs to survive.
Clams could help interrupt that process by filtering nutrients from the water, potentially creating better conditions for seagrass to return.
"They suck up nutrients, and nutrients cause algae. Algae interferes with the light getting down to the seagrass blades, and that then causes the decline in seagrass," Yustin said. "So we think that these clams can help to make conditions better for the seagrass."
Yustin said the project is an unusual approach to restoration, with researchers and environmental managers exploring new ways to address the lagoon's problems.
"It's pretty cutting edge. I mean, there are some cool things going on, and people are trying different things, but it's certainly a pretty unique project," he said.
The county is also exploring a way to expand the effort by releasing clam larvae instead of fully developed juvenile clams. The larvae swim through the water before settling, allowing the county to distribute them more widely at a lower cost.
"We want to take larvae, like clam larvae, before they become little clams, they swim," Yustin said. "We can release them at a fraction of the cost of releasing them at this phase. So we're going to release like 50 million of these larvae into the estuary on an incoming tide, and then they can just go wherever they want."
Martin County is partnering with Tetra Tech to monitor the restoration site, tracking water quality and clam health over time to determine how well the project is working.
Yustin said restoring the lagoon will require patience and continued efforts.
"It took us 100 years to mess up our estuaries. It's going to take time to fix them," he said. "So at the end of the day, we really do need to continue to work through cleaning up water before it enters our estuaries."