A Portrait of the Tampa Bay Estuary
1. What is an estuary?
An estuary is a semi-enclosed body of water where freshwater from the rivers meets and mixes with the saltwater from the ocean. Estuaries are a transition zone from land to sea and support a spectacular abundance and diversity of wildlife. They are considered one of the most productive environments in the world and are often referred to as a "nursery ground" for fish, crustaceans and shellfish, where juvenile marine animals can hide from predators.
2. How big is Tampa Bay?
Tampa Bay is Florida's largest open-water estuary. It is 400 square miles, with a watershed more than five times that large, covering 2,200 square miles. On average, Tampa Bay measures only about 12 feet deep. However, many man-made shipping channels have been dredged to allow large ships a safe passageway. The largest shipping channel is 43 feet deep and 40 miles long.
3. What are some other basic characteristics of Tampa Bay?
Tampa Bay is on the west central coast of Florida between 27.5° and 28°N latitude. The average annual temperature is a balmy 72°. The Tampa Bay area receives an average of 55 inches of precipitation each year and about 60% of the annual rainfall occurs during June through September. Tidal action results in currents of approximately 5.9 ft/s on ebb tides and approximately 3.9 ft/s on flood tides at the mouth of Tampa Bay. Freshwater inflow to Tampa Bay is about 525 billion gallons on an annual basis, with four major rivers (Alafia, Hillsborough, Little Manatee, and Manatee Rivers) contributing about 70%-85% of this. Salinity generally ranges over 25-38 ppt in Lower Tampa Bay, nearest the mouth of the bay. Old Tampa Bay, in the northern part of Tampa Bay, usually has salinities varying over 18-32 ppt and Hillsborough Bay has a salinity range of 15-30 ppt.
4. What is the major source of pollution to Tampa Bay?
Nitrogen is a major pollutant in Tampa Bay. Although it is an essential plant nutrient, excess amounts of nitrogen fuel the growth of algae that clouds the water and robs it of oxygen. Water with an overdose of nitrogen is often a murky pea-green color and is said to be "eutrophic."
Wastewater (sewage) discharges were once a major source of nitrogen to Tampa Bay. However, in the 1970s, major improvements to sewage treatment plants reduced the nitrogen in the wastewater, or "effluent," by more than 90 percent, leading to clearer water and sparking a recovery of seagrasses that continues to this day.
Currently, more than half the nitrogen entering Tampa Bay comes from stormwater runoff from urban and residential areas. Stormwater is the water that runs off the land with rainfall, carrying with it fertilizer and pesticide residues, as well as trash.
About one-quarter of the present nitrogen load to Tampa Bay comes from atmospheric deposition, or air pollution, primarily from power plants and automobiles. Wastewater treatment plants and industrial discharges are relatively small sources of nitrogen loading to the bay today.
5. What are some other threats to the bay?
Other major threats include significant loss of habitat. Since the 1950s, almost half of the bay's original marshes and mangroves have been lost, half of its natural shoreline has been altered by construction of roads, causeways, subdivisions and other development, and 40 percent of its underwater seagrass beds have disappeared.
6. What are some important habitats in Tampa Bay?
Mangrove forests are important because they trap and cycle pollutants and they provide shelter and nursery areas for fish, crustaceans, and shellfish. Mangroves also function as the basis of the food chain for a multitude of marine species such as snook, snapper, tarpon, jack, sheepshead, red drum, oysters, crabs and shrimp. In addition, mangrove forests protect uplands from storms, waves and floods. They are the dominant wetland vegetation type in the Tampa Bay watershed. Tampa Bay supports red, black and white mangrove species. Red mangroves grow closest to the water, followed by blacks and then whites.
Salt marshes are composed of a variety of plants, mainly rushes, sedges and grasses. Animals seek refuge from predators in the thick marsh vegetation. After salt marsh plants die, microorganisms break the plants down into detritus, which serves as a food source for many small animals. As tidal waters move up into the marsh and then retreat, detritus is carried and distributed throughout the estuary. The primary salt marsh species in Tampa Bay is spartina alterniflora, or smooth cordgrass.
Seagrass beds help maintain water clarity by trapping fine sediments and particles with their leaves. They stabilize the bottom with their roots and rhizomes in much the same way that land grasses slow soil erosion. They provide shelter for many fishes, crustaceans, and shellfish; and they and the organisms that grow on them are food for many marine animals and water birds. Three types of seagrasses dominate in Tampa Bay: Halodule wrightii, or shoal grass; Thalassia testudinum or turtle grass; and Syringodium filiforme or manatee grass.
7. What is the Tampa Bay Estuary Program?
It is an intergovernmental partnership coordinating the overall restoration of the bay according to a comprehensive Management Plan adopted in 1997. TBEP is one of 28 National Estuary Programs around the country and is a partnership of Pinellas, Hillsborough and Manatee counties, the cities of Tampa, St. Petersburg and Clearwater, the Florida Department of Environmental Protection, the Southwest Florida Water Management District and the U.S. Environmental Protection Agency. The Program is governed by a Policy Board composed of elected officials and a Management Board of top-level bay managers and administrators -- working with both technical and citizen advisory groups.
8. What is an invasive species?
Invasive species are any non-native plant or animal that is introduced either intentionally or accidentally to a particular area that creates a negative impact on the surrounding environment. Although there are many non-native plants and animals that are beneficial to an area, such as citrus trees in Florida, many plant and animal species can destroy the habitat they're introduced to because they lack the natural controls such as climate restrictions and predators that normally exist in their natural home range. These plants and animals then become invasive, pushing out native plants and animals, disrupting entire ecosystems, and costing millions of dollars to control or eradicate. Many scientists now rank invasive species second only to habitat loss as a cause of global extinctions.
9. How do invasive species get from place to place?
There are several ways invasive species become introduced to different environments. They include: introduction by the discharge of ballast water (water taken on by ships in one place for balance and buoyancy, and discharged in another); release of animals purchased from pet or aquarium shops; cultivation of non-native food or ornamental plants; escape from aquaculture facilities; hitchhiking aboard pleasure boats (larval mussels or algae may attach to boat propellers or hulls and be transported from one waterway to another); and the dumping of bait buckets.
10. What is a Brazilian Pepper?
The Brazilian Pepper tree (Schinus terebinthifolius) is a member of the same family as poison ivy, poison oak, and poison sumac and is considered highly invasive. Brazilian Peppers are large, multi-trunked shrubs that can grow 40 feet tall. They are evergreens with glossy, bright leaves and the female Brazilian Peppers produce tiny yellowish-white flowers in spring, and clusters of small red berries in late fall. Brazilian Peppers are on the State of Florida's prohibited plant list. It is illegal to cultivate, sell or transport them because they are capable of rapid proliferation, wiping out everything in their path and destroying entire ecosystems of plants and animals.
11. What do I do if I have a Brazilian Pepper on my property?
Call your County Cooperative Extension Service for help on how to eradicate the plant yourself, or find professionals who can do it for you. There are commercial herbicides available at garden centers that are successful in killing pepper trees, if the chemical is applied on the freshly cut stump.
12. What are manatees and why is it important to protect them?
The Florida manatee (Trichechus manatus latirosris) is a large, gray or gray-brown, spindle-shaped, plant-eating marine mammal found in Florida's shallow coastal waters, rivers and springs. The average adult manatee is about 10 feet long and weighs about 1,200 pounds. Manatees spend about six to eight hours a day feeding and about two to 12 hours a day resting on the bottom or at the water's surface. They move freely within salt, brackish and fresh water habitats often in depths less than six feet deep. This puts them at great risk from speeding boats, especially since manatees often cannot swim fast enough or dive deep enough to get out of harm's way. Manatees are an endangered species protected under the federal Endangered Species and Marine Mammal Protection Act and the Florida Manatee Sanctuary Act.
Protecting manatees is important for a number of reasons. Manatees help control the overgrowth of seagrass beds by continuous grazing, which reduces the need to use chemicals as a form of aquatic control. Manatees are also messy eaters and help promote seagrass growth by dispersing seagrass seeds around the bottom. In addition, manatees are considered an ecosystem indicator - their health provides clues to the health of our coastal environments.
13. What are some of the different habitat restoration projects going on in Tampa Bay?
Tampa Bay habitat restoration projects include transforming manmade pits back into shallow, meandering wetlands; installing artificial oyster reefs; and planting salt marsh grass, sea oats or other native plants.
14. Why is it important to landscape with native plants?
Planting native and other drought-tolerant plants in your yard helps conserve water - a precious resource in Florida. Native plants cost less to maintain and they require fewer chemicals. Conserving water reduces stress on freshwater supplies and less chemical maintenance of lawns and exotic plants reduces the amount of polluted runoff into the bay.
15. What are the major species of fish found in Tampa Bay?
More than 200 species of fish are found in Tampa Bay. The most numerous fish are the small baitfish. The most popular game fish in Tampa Bay are redfish, mullet, sheepshead, snook and spotted seatrout.