Officials: Seagrass plantings growing, flowering in river
Efforts to restore lost seagrasses in the Caloosahatchee are proving promising, with planting taking hold, growing and flowering, according to the Charlotte Harbor National Estuary Program.
The toxic algae bloom prevented monitoring of the plantings for months; however, surveys of them recently week revealed the following:
– Site 1 (furthest downstream): Eelgrass was observed in four of the five GrowSAV Herbivory Exclusion Devices. The protective coverings were not removed during the initial inspection, but most likely has grazed upon grass inside as well.
– Site 2 and 3: Eight of the 10 planting sites had very dense eelgrass. The grass is expanding outside of the GrowSAV Herbivory Exclusion Devices and flowering inside. A total of two flowers appeared to have been germinated and are producing seeds. It is believe that this is the first time in the 21st Century where there has been seed pods growing in the lower river.
– Site 4: The one planting site (of five total) where the GrowSAV Herbivory Exclusion Devices was secured to the bottom had eelgrass growing. The other four sites were compromised by grazers.
– Site 5 (furthest upstream): Sparse eelgrass was present, though this area appears to be negatively impacted by water depth and grazing from blue crabs.
The Charlotte Harbor National Estuary Program, Calusa Waterkeeper, and Sea & Shoreline Aquatic Restoration have been working with residents and volunteers to replant seagrasses in the tidal Caloosahatchee. The project aims to restore the tidal Caloosahatchee’s submerged aquatic vegetation – or SAV – communities.
“Making progress in restoring the seed source for the lost seagrass beds in the tidal Caloosahatchee is a tremendous achievement,” Jennifer Hecker, executive director of the Charlotte Harbor National Estuary Program, said. “Seagrasses are the base of our aquatic food chain, supporting everything from crabs to endangered manatees. Continuing this project to learn how and where we can replenish them will have a significant impact in improving our ability to restore water quality and the ecology in the area.”
The species planted are Ruppia maritime (commonly known as Ruppia) and Vallisneria Americana (commonly known as tapegrass or eelgrass). Aquatic vegetation is an important part of estuarine ecosystems, providing vital reproductive and nursery habitat for fish in addition to food for grazers, such as manatees and turtles. It also improves water quality and clarity by removing nutrients and sediment. The Caloosahatchee has historically supported vast seagrass beds. However, much coverage has been lost in recent years due in part to alterations in water flows to the tidal Caloosahatchee.
The project has entailed creating five planting areas covered by herbivore exclusion cages, which protect the seedlings while they are getting established, in five locations on the north and south shores of the Caloosahatchee between the Interstate 75 and US 41 bridges.
The sites were selected to be along waterfront residents who wanted to participate. CHNEP and Calusa Waterkeeper staff and volunteers, along with staff from Sea & Shoreline, installed the plantings and cages and have been participating in the ongoing maintenance and monitoring efforts.
“It feels really good to field verify the extensive research documenting the methods to re-establish beneficial eelgrass in waterways. Due to the significant investment of water storage/release north of the Franklin locks, this project will only get better with time,” Carter Henne, president of Sea & Shoreline and a contractor for the project, said. “However, what encourages me most is that it allows waterfront homeowners to make a significant positive impact to their property. I am very happy to see local stakeholders taking an active role in restoring trophic food webs and the nutrient buffering capacity in the river. I believe this model of local engagement can and should be encouraged in other areas of the state suffering from lack of submerged aquatic habitat.”
The exclusion cages are to be removed in the next month or so, with monitoring ongoing for a few more months thereafter. The results of the project will also be used to inform ongoing seagrass restoration efforts.
“Though promising to see some seagrass growth as a result of this project, significantly better water quality and flow management regulations will be needed to sustain it and allow it to grow year-round in order to restore the lost seagrass beds,” John Cassani, with Calusa Waterkeeper, said.
The project was funded by the CHNEP, which applied for and was awarded a grant from the Florida Department of Environmental Protection’s Florida Coastal Management Program, with monies provided by the National Oceanic and Atmospheric Administration.