Charlotte Harbor and its adjacent estuaries make up one of the most pristine and productive coastal ecosystems in the state of Florida. To protect these coastal areas for the enjoyment of future generations, the Florida Legislature has designated most of the waters within the greater Charlotte Harbor complex as aquatic preserves which encompass over 160,000 acres of submerged land and water.

One of the goals of the Charlotte Harbor Aquatic Preserve program is to protect and enhance the health and functioning of seagrass habitats within the Charlotte Harbor complex. Seagrasses are an important resource crucial to the maintenance of shallow estuarine environments. Seagrasses provide:

• a primary productive food source for the estuarine system,
• shelter, spawning and nursery habitat to many aquatic organisms,
• reductions in turbidity, facilitate sediment stability and aid in nutrient cycling.

Because of the critical habitat and water quality benefits provided by seagrasses, they are often identified as both keystone and indicator species.

The predominant seagrass species found in the estuaries of Charlotte Harbor are shoal-grass (Halodule wrightii), turtle grass (Thalassia testudinum), and manatee grass (Syringodium filiforme) although other species may be locally abundant.

To date aerial surveys have been the most widely used tool to determine current seagrass locations and changes over time, however, these surveys do not however provide information about species type, health, zonation, or changes with time. Seagrass health, distribution and abundance is largely determined by the amount of light available to the seagrass blades. Water quality variables such as algae, turbidity, suspended solids, color, and chlorophyll affect the amount of light penetrating through the water column. Light attenuation is also affected by the amount of epiphytic growth on the seagrass blades.

The FDEP, Charlotte Harbor Aquatic Preserve staff began seagrass mapping studies at 52 stations in Charlotte Harbor during October - December 1999. A major focus of this monitoring effort aims to link water quality and seagrass health.

All transects are monitored annually, in the fall, however, it is anticipated that monitoring will be increased to twice a year, July and February, to correspond with times of maximum and minimum seagrass abundance. Monitoring sites are reached using a shallow draft boat, and observations are made by snorkeling.

Transects are located with a GPS. Each transect consists of a fixed line, determined from a compass heading which extends from the shoreward seagrass edge out to the deep edge of the grass bed. Measurements include species composition, percent coverage, blade length, shoot density, water depth, sediment, and epipyte load. Water quality parameters include secchi, photosysnthetically active radiation (PAR), dissolved oxygen, salinity, and temperature.

Long term fixed transect monitoring will be a useful tool in detecting site-specific changes over time by determining and documenting declines or improvements in seagrass health.  This type of detailed monitoring is needed to discern between naturally occurring events and human introduced events, which unnaturally threaten the health of the seagrass. In addition, transect monitoring will aid in the interpretation of aerial photography and seagrass maps.