Seagrasses: The roof that covers many...
But with a foundation that is anything but solid! This 'House' analogy may be weak, but it gives a good idea of both the role and the current status of seagrasses throughout our area. Seagrasses support over 70% of Florida's fisheries by providing food and critical habitat, but since the turn of the century, Florida has lost over half of its seagrass beds due to development, dredging, pollution and increased boating activity. It is our choices that decide whether this trend continues or if healthy seagrasses serve to nurture our trout, redfish, flounder, grouper, numerous types of baitfishes, and many, many more important ocean species.
Seagrasses are submerged flowering plants found in shallow marine waters in bays, lagoons, and along the continental shelf in the Gulf of Mexico. Seagrasses provide food, habitat, and nursery areas for thousands of species. Seagrasses perform numerous functions:
Ocean bottom areas without seagrass are vulnerable to intense wave action from currents and storms. The extensive root system in seagrasses, which extends both vertically and horizontally, helps stabilize the sea bottom in a manner similar to the way land grasses prevent soil erosion. With no seagrasses to diminish the force of the currents along the bottom, Florida’s Gulf coastline, businesses, and homes can be subject to greater damage from storms.
Seagrasses provide food, shelter, and essential nursery areas to commercial and recreational fishery species and to countless invertebrates living in seagrass communities. Again, our grouper, redfish, trout and many, many other important species rely on healthy seagrass beds.
While some animals, like the Florida manatee and green sea turtle, graze directly on seagrass leaves, others use seagrasses indirectly to provide nutrients. Detritus from seagrasses feed the worms, crabs, and filter feeders that serve as the base for our area's rich food chain.
The relative safety of seagrass meadows provides an ideal environment for juvenile fish and invertebrates to conceal themselves from predators. Seagrass leaves are also ideal for the attachment of larvae and eggs, including those of the sea squirt and mollusk. Much of Florida’s recreationally and commercially important marine life can be found in seagrass meadows during at least one early life stage.
While seagrasses are ideal for juvenile and small adult fish for escape from larger predators, many infaunal organisms (animals living in soft sea bottom sediments) also live within seagrass meadows. Species such as clams, worms, crabs, and echinoderms, like starfishes, sea cucumbers, and sea urchins, use the buffering capabilities of seagrasses to provide a refuge from strong currents. The dense network of roots established by seagrasses also helps deter predators from digging through the substratum to find infaunal prey organisms. Seagrass leaves provide a place of anchor for seaweeds and for filter-feeding animals like bryozoans, sponges, and forams.
Seagrasses help trap fine sediments and particles that are suspended in the water column, which increases water clarity. When a sea floor area lacks seagrass communities, the sediments are more frequently stirred by wind and waves, decreasing water clarity, affecting marine animal behavior, and generally decreasing the recreational quality of coastal areas. Seagrasses also work to filter nutrients that come from land-based industrial discharge and stormwater runoff before these nutrients are washed out to sea and to other sensitive habitats such as coral reefs.
Although seagrass is not a commodity that is directly cultivated in Florida, its economic value can be measured through other industries, such as commercial and recreational fisheries and nature and wildlife tourism, which rely on this habitat to survive. Since most of Florida’s fishery species (approximately 70%) spend at least part of their life cycle within seagrass communities, seagrasses are vital to the survival of these fishing industries.
- University of Florida Museum of Natural History - Seagrasses
- Simple steps to preserving seagrass from FWC