Spring 2008 Issue
Watching grass grow
Barry’s Dr. Silvia Macia is trying to save a vital but often overlooked link in South Florida’s marine ecosystem
By Julianna Pietak
The shallow water of Biscayne Bay teems with life – bonefish, nurse sharks, sea urchins. But on this December morning, Barry University’s Dr. Silvia Macia and her two student researchers are concerned with another form of marine life, perhaps the most important but overlooked in this network – seagrass.
Even from above the surface of the water, the damage is easily visible. Sandy trails snaking through the seagrass, or propeller “scars,” are evidence of the destruction left behind from boat propellers. The Florida Department of Environmental Protection estimates that more than 30,000 acres of seagrass in South Florida suffer this type of damage. And, aside from the obvious harm caused by boat propellers, the region’s seven seagrass species have seen increasing damage from a variety of sources, including South Florida’s ever-expanding coastal development.
“A lot of damage comes from dredging and coastal construction,” Macia said. “Every time they have to dredge something out, even if they’re not dredging seagrass beds, it still affects it.”
Today, however, Macia and her two biology students, Robin Cascioli and Michelle Metcalf, are not looking for damage. Instead, they are searching for signs of regrowth – 50 tiny seedlings under the sandy currents of Biscayne Bay.
The seedlings are the product of Macia’s latest research, refurbishing and replanting seagrass beds in South Florida. While many scientists have researched and implemented other options for refurbishing these ecosystems, Macia, an assistant professor of Natural and Health Sciences at Barry, has taken an originally meticulous approach. With the help of Barry students, she collects seagrass seedlings from South Florida beaches and cultivates them in her lab. The seedlings are then replanted in damaged areas of Biscayne Bay, such as the propeller scar outside Crandon Park, which is the only one of its kind in the country.
Most restoration projects have focused on pulling up plugs of seagrass from healthy beds and replanting them in damaged areas. But, the problem with this is two-fold, Macia explains. Seagrass stems, or rhizomes, grow sideways while the roots grow down. If the bed is cut vertically, it will destroy this stem, and the grass is unable to grow. In the process, pulling up these plugs also damages the existing healthy bed.
“Even the ones that work, it still damages the seagrass bed,” Macia says. “It’s better if it works, but still better if you can find a way not to damage the seagrass while doing it.”
Rather than focusing on these plugs, Dr. Macia’s attempt is unusually hands-on – germinating individual seedlings in her lab, depositing them in more stationary peat pots, and then planting them within the damaged seagrass bed. Together, Macia, Cascioli and Metcalf monitor the progress of the project – wading through Biscayne Bay, indentifying each seedling in the “prop scar,” and snorkeling to measure and record any underwater growth.
The successful growth of the seedlings, however, will affect more than just this “prop scar.” Their success may have implications for marine ecosystems far beyond this seagrass bed in Biscayne Bay.
“The seagrass itself creates the ecosystem,” Macia says. “It’s kind of like a forest; you can’t have a forest without the trees.”
And South Florida waters are dependent upon these forests. The seagrass meadow of South Florida is the largest one of its kind in the world, and has helped create the world-class fishing of South Florida and the Florida Keys. Many commercially important marine species, such as shrimp, spiny lobster, stone crabs, bonefish and snappers are dependent on these underwater forests. In fact, more than 70 percent of Florida’s recreational and commercial fish spend part of their lives in these shallow water estuaries. In addition to holding together these marine ecosystems, the seagrass also quite literally holds together the seafloor, stabilizing the sand and keeping sediments from damaging water quality.
“Without seagrass you’d just have bare sand, and not much can live in the bare sand,” Macia said.
Although this is Macia’s first project involving restoration, she has been active in seagrass research for more than 11 years, six of them at Barry. Her research has been supported by a grant from the Environmental Protection Agency, which funded the university’s research boat and provides stipends for her student researchers.
“This research has given me a lot of hands-on activities to do,” said Cascioli, a junior biology major. “It’s nice to get out on the boat and go out in the environment instead of doing beach scenes. It’s frustrating sometimes when there’s not success, but it’s very valuable.”
If successful, Macia will bring her research to local and national agencies, such as the National Parks system who have already expressed interest in the project. Macia also recently received an additional permit from Miami-Dade County that will broaden her research to another site, replanting in another, more sheltered area of Biscayne Bay
Turtle grass, which is the subject of Macia’s research, is the most common seagrass species found in South Florida, but any species that grows in the same manner may benefit from this project. With more than 60 species of seagrass living in coastal habitats worldwide, Macia’s research has the potential to have far-reaching effects.
“It’s the kind of thing most people aren’t interested in at all,” Macia said. “But it’s so important and so common, it’s found throughout the world.”