|Seagrass ecosystem characteristics and research and management needs in the Florida Big Bend|
Mattson, R.A. (2000). Seagrass ecosystem characteristics and research and management needs in the Florida Big Bend, in: Bortone, S.A. (Ed.) Seagrasses: monitoring, ecology, physiology, and management. pp. 259-277
In: Bortone, S.A. (Ed.) (2000). Seagrasses: monitoring, ecology, physiology, and management. CRC Marine Science Series, 16. CRC Press: Boca Raton. ISBN 0-8493-2045-3. 318 pp., more
In: Kennish, M.J.; Lutz, P.L. (Ed.) CRC Marine Science Series., more
The seagrass ecosystem present in nearshore waters of the Florida Big Bend coast is the second largest in the eastern Gulf of Mexico, covering about 3,000 km2. This area (from the St. Marks to the Anclote River) generally receives less research and management attention compared to other seagrass areas in Florida (i.e., Florida Bay, lndian River Lagoon). lt represents the northern distributional limit of American tropical seagrasses. The major seagrass species are Thalassia testudinum, Syringodium filiforme, and Halodule wrightii. Halophila engelmanni, Halophila decipiens, and Ruppia maritima are also present but constitute a lesser component of coverage and standing crop. Benthic green algae in the order Siphonales and drift algae (primarily Rhodophyta) are major floristic components of these beds, in some areas standing crop of algae exceeds that of seagrasses.Four subregions may be recognized in the northern portion of the region: Apalachee Bay, Deadman Bay, Suwannee Sound and adjacent coastal waters, and Waccasassa Bay. Submerged vegetation coverage was estimated by a 1972 NMFS study: Apalachee Bay 128.0 km2; Deadman Bay 7.4 km2; Suwannee Sound 32.3 km2; and Waccasassa Bay 98.0 km2. These data are for inshore, shallow-water areas (primarily < 2 m MLW depth). Other submerged vegetation mapping studies conducted in the region misclassified vegetation coverage in some areas or only mapped in a spatially defined region. Limited amounts of field data are available to describe the seagrass/benthic algal communities in the Big Bend, with few studies reporting standing crop, short-shoot densities, or productivity data. Differences between seagrass community characteristics in the Big Bend vs. Florida Bay have been attributed in part to climatic differences. Studies conducted in Apalachee Bay indicate that reduction in light quantity and quality associated with discharge of bleached kraft mill effluent have resulted in significant reductions in seagrass coverage and standing crop. Because seagrasses are influenced by water clarity, which can be affected by a variety of water quality factors, they can serve as biological indicators to evaluate the effectiveness of efforts to protect water quality. A key component leading to this would be determining minimum water quality characteristics needed to maintain suitable water clarity. Given the current high ecological integrity of this portion of the Big Bend coast (perhaps the least disturbed in Florida), it is desirable to collect additional descriptive data (both mapping and field data) at an adequate number of sample sites to document current seagrass community conditions and form the basis for a monitoring program to assess this condition on an ongoing basis. The results from studies conducted in this area and other estuaries could be used to derive protective water quality criteria to maintain existing seagrass coverage and community composition. An important research question is whether the seagrasses in this area are more sensitive to environmental perturbation than those in areas in the southern parts of the state, since they reside at the northern limit of their distribution and are subject to natural climatic stresses.