Seagrass: Rainforests of the sea

Reel time seagrass
A full moon low tide exposes a seagrass meadow. - Rusty Chinnis | Sun

The seagrass meadows that surround Anna Maria Island are mostly hidden from view and are only exposed on extreme low tides during the full and new moons. Magical and mysterious like a tropical rainforest, they harbor and support a tremendous array of life.  And while we have a limited understanding of this web of life, it is responsible for much of the beauty and diversity of the area.

Seagrasses are flowering plants that serve a number of important functions. Since they flower, they require sunlight and are limited to clear, shallow waters. They produce oxygen, bind sediments and baffle wave action, while cleansing coastal waters.

Seagrass roots, their leaves, and the epiphytes and microalgae that cling to them, clean water by converting dissolved nutrients into plant matter. Besides giving us clean air and clear water, seagrasses are home to a vast array of organisms that provide food and shelter for fish, crustaceans, shellfish, manatees and wading birds.

While there are 52 species of seagrasses worldwide, only seven are found in Florida.  Locally they include turtle (Thalassia testudinum), shoal (Halodule wrightii) and manatee grasses (Syringodium filiforme). The loss of these species has been extensive throughout Florida.

At one time Tampa Bay had lost 81 percent of its historical cover, Sarasota Bay 35 percent and Charlotte Harbor 29 percent.  Poor watershed management (storm water run-off and sewage disposal) dredge and fill operations and scaring from boats have taken a heavy toll on Florida’s seagrasses.

Fortunately, the influence of citizens through organizations like Sarasota Bay Watch,  Tampa Bay Watch, the Tampa Bay National Estuary Program and the Sarasota Bay Estuary Program have instituted programs that are beginning to turn the tide on water quality. The increase in water quality has led to a resurgence in local seagrass coverage. In Tampa Bay, sea grass coverage has reached 41,655  acres, surpassing a goal of 38,000 acres set in 2014.

Anglers, from experience, are aware of the importance of these seagrasses. They experience first hand the myriad interactions that produce fertile fisheries. They may not understand the intricate web of existence that proceeds from the microscopic level to the fish on the end of their line, but they reap the benefits none the less. Government scientists (NOAA) consider seagrasses to be of such importance, that they have adopted a no net loss policy to manage them.  Despite this noble pronouncement, seagrasses remain under assault.

The loss of valuable seagrass beds must be a higher priority. Fortunately watershed management, replanting, avoidance of direct impacts to existing grasses and mitigation are helping to approach those lofty and critical goals.

It is a foregone conclusion that development will continue to impact coastal areas and their seagrass resources. It is vital that decisions are made that will allow needed development while forming policies that will protect the quality of our most valuable local resource, the Gulf, bay and its seagrass beds. To reject proper growth management is to squander the birthright our children and future generations. Enlightened citizens, anglers and their interest groups must take part in this decision-making process.

Cost considerations often eclipse concerns for seagrasses, but research reveals the true value of these resources. A  study (Virnstein and Morris 1996) conducted in the Indian River Lagoon estimated the value of seagrass to be $12,500 per acre, per year, based solely on economic values derived from recreational and commercial fisheries.

Having established the importance both ecologically and economically of seagrasses, it is crucial that we develop rules and procedures that assure we maintain (no net loss) the current standing stock. A wiser decision would be to enact management policies mandating an increase in these rainforests of the sea.