For decades, FWRI scientists have carefully monitored seagrass health throughout Florida, witnessing both alarming die-offs and encouraging signs of recovery. From 2018 to 2020, Tampa Bay saw a concerning reduction of its seagrass meadows, with a loss of over 16 percent, or more than 6,350 acres. These losses not only affect the biodiversity of our waters, but also our coastal water quality and the survival of vulnerable species like manatees. Monitoring macrophytes, both seagrasses and macroalgae, provides us with a comprehensive view of the condition and diversity of these underwater meadows. We aim to use our research findings to help resource managers make informed, effective science-based decisions for Florida’s seagrass conservation and restoration.
Seagrasses of Florida
Thalassia testudinum is the largest subtropical seagrass species in the Atlantic and can be identified by its broad, flat leaves. It can form large continuous meadows and is found in many Florida estuaries. It generally grows in areas with near-ocean salinities 30-40. In the Gulf of Mexico, turtlegrass is considered a climax species, which can dominate a meadow by outcompeting other seagrasses after it is first colonized by a pioneer species (like shoal grass). Turtles love to munch on this grass, hence the name turtlegrass!
Syringodium filiforme is shaped very differently from all other Florida seagrasses because its leaves are cylindrical, not flat. Manatee grass cannot tolerate large swings in salinity, it prefers salinities greater than 20 but not too salty. It looks like green spaghetti but does not taste like it, well, maybe to a manatee!
Halodule wrightii grows all throughout Florida. Its leaves are narrow and flat with a blunt square tip. It can tolerate a wide range of salinities and is considered a pioneer species, often the first to colonize a disturbed area. Shoal grass is thus named because it can grow in water too shallow for most seagrasses, often on shoals that can be exposed at low tide.
Ruppia maritima is the only seagrass species able to grow in both fresh and saltwater. It is typically found in the lower salinity areas of Florida estuaries. Like shoal grass, widgeon grass has narrow, flat blades but with pointed tips. The two are hard to tell apart, but widgeon grass is easily distinguished from shoal grass when it flowers.
Halophila engelmannii is 1 of 3 species of the genus Halophila found in Florida and is the only species found in Tampa Bay. It is the easiest species of Halophila to identify because of its whorl of 5-7 leaves. Halophila often grows among other seagrasses forming an understory to the seagrass canopy. They can also grow at greater depths than other seagrasses, occasionally over 100 ft deep!
Fisheries Habitat Assessment Program (FHAP)
The Florida Bay Fisheries Assessment Program is a project designed to assess the distribution and status of Florida Bay fisheries habitats in which seagrasses and macroalgae are present.
Seagrass Integrated Mapping and Monitoring Program (SIMM)
The Seagrass Integrated Mapping and Monitoring program was developed by FWRI to protect and manage seagrasses in Florida by providing a collaborative resource for seagrass mapping, monitoring, and data sharing.