Seagrass-planting experiment aims to restore Indian River Lagoon
Updated On: Jul 25 2013 09:07:00 PM EDT
Scientists transplanted tufts of seagrass along an otherwise bald Indian River Lagoon bottom Wednesday in hopes of growing back the once-lush fish habitat that algae blooms doomed.
No one knows whether the $110,000 experiment will work or whether the cloudy waters that smothered seagrass during the past few years will return to do so again.
But researchers hope the grass transplants teach them the best ways to grow back a vital nursery habitat for fish and crabs, as well as the manatees’ favorite meal.
“This used to be — as far as you could see — grass,” Adam Gelber, a senior scientist with Atkins North America, said as he and two other scientists transplanted shoal grass along Sebastian Inlet’s interior.
At the inlet, their environmental consulting firm is planting seagrass harvested in Vero Beach. That effort ispart of a larger project that could transplant grass at up to 30 sites in the lagoon — but likely fewer — occupying about 1 acre of lagoon bottom. The project ranges from Merritt Island National Wildlife Refuge to Titusville, to Vero Beach.
Seagrass provides prime habitat for fish, crabs and other marine life and is considered a key barometer of the estuary’s overall health. Each acre of seagrass supports about 10,000 fish and $5,000 to $10,000 in economic activity in the lagoon region, according to St. Johns River Water Management District and other studies.
Transplants are just one way biologists hope to restore some 74 square miles of seagrass lost since 2009, much of it clouded out by algae.
The scientists harvest the seagrass with hand tools only — no machinery — and manually install the grass at the recipient study sites.
They use shoal grass, because it’s among the fastest growers.
They place metal “manatee cages” over many of the transplants to keep ravenous seacows from chomping the experiment bare. But at least one manatee was quick to find this week’s plantings among the inlet’s seagrass-starved shoals. After Atkins consultants planted the first tufts of grass, they returned later that day and found evidence a seacow had made a snack of their work.
“That night, we came back to look at it and it was already bitten down,” said Don Deis, a senior scientist with Atkins.
The St. Johns River Water Management District’s planned cost for the larger, three-year transplant project is $85,000. The Sebastian Inlet District chipped in about another $25,000.
Similar grass transplants in recent years have shown success along the inlet’s interior, patching boat propeller scars and other barren spots. The inlet district saw grass thrive after it had to transplant grass to make up for seagrass impacted by an August 2007 dredging of the channel. But large influxes of algae-ridden water from the north wiped out most of the grass along the inlet shoals, scientists said.
The lagoon has undergone severe seagrass loss since 2011, when an unprecedented phytoplankton “superbloom” clouded out the sunlight seagrasses need to grow.
A brown tide bloom that first struck the lagoon last summer re-emerged this year in the northern lagoon and southern Mosquito Lagoon. The same algae species, Aureoumbra lagunensis, bloomed almost eight years in a row in Laguna Madre, Texas, making it the longest harmful algae bloom ever recorded.
In all, the lagoon has lost an estimated 47,000 acres of seagrass since 2009.
Not only grass has died. More than 110 manatees may have perished from the same mysterious illness since July 2012, state wildlife biologists suspect. And at least 54 bottlenose dolphins have floated up dead in the lagoon since Jan. 1, as well as 250 to 300 brown pelicans earlier this year.
Donor sites where seagrass will be harvested include just off Pine Island on Merritt Island, just north of A. Max Brewer Memorial Parkway in Titusville and near Vero Beach.
Grass harvested from the donor sites grows back quickly.
The transplant sites are 100 meters from shore and cover about 100 square meters, according to the U.S. Army Corps of Engineers permit that authorized the project.
One positive sign scientists find at Sebastian Inlet is the emergence of Johnson’s seagrass. It’s pioneering roots typically precede a seagrass rebirth.