Seagrass: Rainforests of the sea
From the June 4, 2008 Issue
SUN PHOTO/RUSTY CHINNIS
Seagrasses are vitally important for species like this sea
trout that was landed on a fly by Captain Rick DePaiva.
The seagrass meadows that surround our barrier islands are mostly hidden from view. As magical and as mysterious as any tropical rainforest, they harbor a tremendous array of living creatures. And while few directly experience this web of life, it is responsible for much of the beauty and diversity of coastal Florida. Seagrasses are flowering plants that serve a number of important functions to the environment. Because 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 micro algae that cling to them, clean water by converting dissolved nutrients into plant matter. Besides giving us clean and clear water, sea grasses are home to a vast number of organisms that provide food and shelter for fish, crustaceans, shellfish, manatees and wading birds.
Of the 52 species of seagrasses worldwide, only seven are found in Florida. On Florida’s west central coast they include turtle (Thalassia testudinum), shoal (Halodule wrightii) and manatee grasses (Syringodium filiforme). The loss of these species has been extensive throughout Florida. Tampa Bay has lost 81 percent of its historical cover, Sarasota Bay 35 percent and Charlotte Harbor 29 percent. Poor watershed management (stormwater run-off and sewage disposal), dredge and fill operations and scaring from boats take a heavy toll on Florida’s seagrasses.
Fortunately the influence of citizens through organizations like Tampa Bay Watch, the Tampa Bay Estuary Program and the Sarasota Bay Estuary Program have instituted programs that are beginning to turn the tide on water quality.
Anglers, from experience, are aware of the importance of these prolific, shallow beds. 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. Watershed management, replanting, avoidance of direct impacts to existing grasses, and mitigation, are avenues to reach those goals.
Mitigation involves the replacement of seagrasses impacted by residential and commercial development. In theory there should be at least one acre of seagrasses created (that flourishes and survives) for every acre that is destroyed. However, the literature reveals that the effectiveness of mitigating seagrass damage is considered, even among the leading wetland scientists, marginal at best.
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 resources: the Gulf, bay, and its seagrass beds.. To reject proper growth management is to squander the birthright of our children and future generations. Enlightened citizens, anglers and other 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.