Seagrass Ecology

Sea Grass Bed Changes in Florida Bay : 1995-1997

Florida Bay Project Profile - 6

---

Question: Where are the seagrass beds distributed? How healthy are they? What changes in seagrass community structure have occurred since 1995?

Experiment: In the spring and fall, over 300 randomly chosen sites were sampled in ten basins in Florida Bay. Each site was visually surveyed for seagrass and macroalgal species composition and cover. Additionally, each spring, core samples are taken to estimate the overall health and growth of the seagrasses.

Findings To Date: Seagrass communities continue to undergo dramatic changes. In the central and western Bay, turtle grass (Thalassia testidunium) distribution and abundance has been significantly reduced. The greatest losses of turtle grass have occurred in the western portion of Florida Bay. Here, plant loss appears to be related to light limitation associated with chronic turbidity. Shoot densities have declined in an overall "stand-thinning" pattern. Individual shoots exhibit broader and wider leaves, indicating the plant is compensating for light limitation by increasing its surface area for photosynthesis. In other parts of the Bay, seagrass loss is patchy, resembling the original die-off of 1987. The losses in these areas, appear to be related to the abundance of a marine slime mold (Labyrinthula).

In contrast, shoal grass (Halodule wrightii) beds have become more dense and more widely distributed throughout the Bay.

Status: Ongoing

Restoration Impacts: Seagrasses and other marine plants are important eco-indicators. The findings of this work have established a baseline for the macrophyte community of Florida Bay. A regional management database is being programmed to model responses of future water management alterations and to assess the effectiveness of restoration efforts in Florida Bay.

Funding Source: Florida DEP, U.S.G.S.

Other Related Profiles:

FBPP - 01
FBPP - 10
FBPP - 15
FBPP - 17