http://gulfsci.usgs.gov/tampabay/conf2002/sea_kellogg/index.html

U. S. Geological Survey, Florida Integrated Science Center, Center for Coastal & Watershed Studies
600 4th Street South, St. Petersburg, FL 33701, Phone: 727-803-8747

Gulf of Mexico Estuaries Integrated Science
Tampa Bay Pilot Study
2nd Annual Science Conference, St. Petersburg, FL, Sept. 19, 2002
Poster Presentations: Seagrass Section

Task Leader: Kimberly Yates, Email: kyates@usgs.gov

Poster Title: Seagrass Restoration in Tampa Bay, Florida

Dawes, Clinton (USF), Meads, Michael (USF), Yates, Kimberly (USGS/GD), Fernandez, Mario (USGS/GD) and Kellogg, Christina (USGS/GD)

Background

Seagrasses form one of the world’s most productive marine plant communities, with some of the most extensive beds occurring in Florida’s estuaries and near shore coastal waters (>2.5 million acres). The communities provide food and habitat for commercial and sport fishing species (e.g. spotted sea trout, tarpon, pink shrimp, spiny lobster), as well as for many types of wading birds and endangered species such as manatees and sea turtles.

However, seagrass meadows are declining worldwide, primarily due to human-induced disturbances. Declines in seagrass coverage in Florida, and Tampa Bay in particular, have been linked to pollution, worsening water quality, coastal development, loss of tidal marshes, and mechanical damage from dredge-filling and prop scarring. About 35% of the seagrass beds have been lost in Florida, with turtle grass (Thalassia testudinum) the most heavily affected. The greatest impacts occur in estuaries like Tampa Bay, which has experienced a greater than 70% decrease in seagrass.

Presently, replanting of damaged turtle grass beds requires damaging a donor bed to obtain transplants because of lack of nurseries. There is both a need for development of nursery stock to supply transplants to impacted areas and techniques to increase growth and survival of damaged beds. Our long-term goal is to formulate procedures for enhancement of growth of turtle grass and to develop land-based nurseries that would remove the need to take plants from donor beds.

The project combined experiments in seagrass ecology, biogeochemistry, microbiology, and analysis of chemical contaminants at two locations: Little Cockroach Bay in the Terra Ceia area and Feather Sound in Old Tampa Bay. The first is adjacent to an aquatic preserve and has healthy seagrass beds near the test site. The second is a highly impacted area and very little native seagrass remains.

Transplantation

Research Questions:

1. Will the use of sediments that initially reduce the anaerobic conditions and allow penetration of gasses and seawater improve survival and growth of turtle grass?

Testing five different types of sediment for transplants:

• Oyster shell
• Limestone gravel
• Coarse sand (20/30)
• Fine sand
• Natural bottom

2. Will planting in degradable containers improve survival during the critical fi rst 3-6
months after transplantation?

Testing four different types of containers:

• cardboard
• peat pots
• pressed paper pots
• commercial containers

3. Will the use of fertilizers enhance the growth of transplanted and
damaged turtle grass beds?

Both liquid and dry fertilizers will be tested.

Comparisons will be made with natural adjacent beds involving blade growth rates, level of root production, and development of new rhizome meristems.

Biogeochemistry

Research Question:

1. How do the metabolism and growth rates of native seagrass beds in Little Cockroach Bay compare to those in Feather Sound?

Measurements of metabolism and growth rates of benthic communities like seagrass beds have generally been accomplished by calculating rates of photosynthesis, respiration, and biogenic calcification from rate changes in key chemical parameters in the water column. This study uses the Submersible Habitat for Analyzing Reef Quality (SHARQ), which uses a flow-through analytical system to continuously measure the following parameters:

in situ salinity

pH

dissolved oxygen

fluorescence

temperature

Water samples are removed from a sample port every four hours to calculate alkalinity.

Microbiology

Research Questions:

1. How do the treatments (different sediments or the addition of fertilizers) affect the bacterial community associated with the turtle grass?

2. Is there a difference between the bacterial communities associated with turtle grass sediments in Little Cockroach Bay and Feather Sound?

3. Can the presence of specific bacteria (by their altering the biogeochemical parameters of the sediment) help the turtle grass re-establish or grow better?

In May and June, sediment samples were taken at both sites from each of the plots to be fertilized, as well as from the plots containing the different sediment types. Extractions were plated on marine agar plates and counted under the microscope to determine viable counts as well as total counts (not all bacteria will grow on a given solid medium). This serves as a background measurement for both sites (Little Cockroach Bay and Feather Sound). A second set of sediment samples will be taken from the plots in October, after the transplanted turtle grass has had time to go through several growth cycles.

Chemical Contaminants

Research Questions:

1. Are there chemical contaminants (from pesticide runoff) in the sediments at either of these sites (Little Cockroach Bay and Feather Sound) that could be negatively affecting turtle grass regrowth?

Sediment cores and samples were taken at both sites in May and June. The samples from Little Cockroach Bay will be analyzed for Chlordane and DDT, while those from Feather Sound will be tested for polyaromatic hydrocarbons (PAH).

Chlordane is a manufactured chemical that was used as a pesticide in the United States from 1948 to 1988. Until 1983, chlordane was used as a pesticide on crops like corn and citrus and on home lawns and gardens. Because of concern about damage to the environment and harm to human health, the Environmental Protection Agency (EPA) banned all uses of chlordane in 1988. Chlordane sticks strongly to soil particles at the surface and can stay in the soil for over 20 years. It breaks down very slowly and does not dissolve easily in water.

DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] was a manufactured chemical widely used to control insects on agricultural crops and insects that carry diseases like malaria and typhus. DDT sticks strongly to soil particles and lasts a very long time; half the DDT in soil will break down in 2–15 years. It does not dissolve easily in water, however, levels of DDT build up in plants and in the fatty tissues of fish, birds, and animals. In 1972, the EPA banned all uses of DDT, except for public health emergencies.

Polyaromatic hydrocarbons (PAH) are a suite of petroleum-based chemicals, many of which are known carcinogens and others that are suspected problem chemicals. Example: Anthracene is used in dye stuffs, insecticides, and wood preservatives.

Image Captions:

Terra Ceia Aquatic & Buffer Preserve in Tampa Bay, Florida.

The SHARQ chamber is 16 (l) x 8 (w) x 4 (h) feet in size and is designed to isolate several cubic meters of water and underlying benthos from the ambient environment.

Donor plants are taken from healthy beds of turtle grass, like the one shown above.

Clinton Dawes and students lead the way to the seagrass- transplantation site.

The SHARQ chamber is 16 (l) x 8 (w) x 4 (h) feet in size and is designed to isolate several cubic meters of water and underlying benthos from the ambient environment.

Submersible Habitat for Analyzing Reef Quality (SHARQ) is assembed at the study site.

Viable bacteria: A petri dish showing viable aerobic bacteria, grown overnight from a sediment sample collected in the seagrass.

Total bacterial direct counts are done under the microscope using a vital stain.

Chemical structure of DDT, an insecticide formerly used to keep mosquito populations in check.

URL: http://gulfsci.usgs.gov/tampabay/conf2002/sea_kellogg/index.html