A PORTRAIT OF THE TAMPA BAY ESTUARY
Tampa Bay is a rich mosaic of fish and wildlife habitats that supplies life-sustaining links in an ecosystem as biologically productive as some of the world's most celebrated rain forests. From coastal mangroves and marshes to underwater meadows of seagrass, from the open bay to the salty mouth of the Gulf of Mexico, each interdependent habitat plays a vital role.
Bay habitats supply food and shelter for creatures as diverse as the great blue heron and the spiny sea urchin. Seagrasses and mangroves, the most prominent of the bay's "aquascapes", contribute significantly to a dynamic food chain that draws nutrients from the bay floor. As seagrass and mangrove leaves decay, they provide food for small creatures that are ultimately consumed by fish and larger predators.
Seagrasses are flowering underwater plants found at shallow depths in protected bays and lagoons and in patches along the continental shelf of the Gulf of Mexico. As a nursery environment, seagrasses support small fish, shrimp, and crabs that hide among the blades and feast on decaying leaves. Seagrasses also help stabilize shifting sands on the bottom of the bay and improve water clarity by trapping fine sediments and particles.
Once plentiful, seagrass beds now cover less than half of their original acreage in Tampa Bay--a loss triggered by dredge-and-fill activity and declines in water quality. Damage from motor boats is severe in areas. As boats carve through shallow grass flats, their propellers cut sandy trenches that may stay barren for years.
Tampa Bay Seagrasses
Click on the name to view a sketch
Turtle grass (Thalassia testudinum) is the most common seagrass in Tampa Bay, accounting for 42 percent of total seagrass coverage. Turtle grass can live in many substrates, from mud to sand and broken shell, and tolerate a wide range of salinities, from 10 to 48 parts per thousand. Turtle grass has long, leafy blades that usually occur in bundles of three to seven. It is used by a variety of organisms, including more than 113 species of algae which attach to its leaves.
Shoal grass (Halodule wrightii) is like a miniature version of turtle grass. For instance, the leaves of turtle grass are about 3/4 of an inch wide, while those of shoal grass are less than a half-inch wide. And turtle grass may grow to 2 feet or more, while shoal grass tops out at about 15 inches. Although both types of grasses are often found together, shoal grass usually holds the distinction of being there first. For this reason, it is known as a pioneer species.
Manatee grass (Syringodium filiforme) has cylindrical rather than flat leaves. It may reach one foot high and is often found mixed with turtle grass in shallow areas of the bay. Manatee grass is generally more tolerant of low salinities and high temperatures than other seagrass species and is often found in tidal flats - where temperatures can get quite high - and in brackish waters near freshwater tributaries.
Mangroves are tropical trees that thrive in salty environments along the water's edge. Like seagrasses, they provide food and cover for a vast array of small fish and animals. Their roots anchor shorelines, and their branches serve as nesting sites for a wide variety of birds. Nearly half of the mangrove swamps that once ringed Tampa Bay have been replaced by development and seawalls.
Loss of this important habitat has contributed to a decline in fisheries throughout the bay. In order to protect mangroves, local and state regulations restrict pruning and removal.
Three species of mangroves are common in Tampa Bay. Red mangroves, typically located closest to the water, are easily distinguished by their tangled reddish roots that branch out over the water. Mounds of oysters frequently colonize at their base. Black mangroves feature numerous finger- like projections, called pneumatophores, that surround the base of the tree. White mangroves, which often occupy the highest elevations of the three species, have no visible aerial root system. The leaves of the white mangrove are yellow-green.
Salt Marshes and Mud Flats
Salt marshes, which are composed of salt-tolerant rushes, sedges, and grasses, occur along the shorelines of estuaries like Tampa Bay in areas where wave action is minimal. These marshes, which periodically become submerged, nourish and protect many fish and animals. They also buffer upland areas from storms and help filter pollutants that run off the land.
Mud flats around the bay's fringe are exposed at low tide. Although these flats are barren of visible vegetation, they are teeming with life. Small crabs, clams, and worms, which burrow in the mud, supply a veritable feast for birds wading at low tide.
Oysters are immobile shellfish that filter water as they feed. Their grayish-white shells are irregular in shape. Live oysters and dead oyster shells form in mounds on the bay floor, creating bars or reefs. Most prevalent near river mouths and in sections of the bay that receive a steady diet of fresh water, oyster bars attract adult snook and redfish, making them popular fishing spots.
Shellfish harvesting is regulated in Florida. For information on seasonal closures and size and bag limits, contact the Florida Marine Patrol.