Gin-Clear Waters of Biscayne Bay
A vast expanse awaits you as you venture from the mangrove shoreline out onto Biscayne Bay. With the wide blue sky above and the gin clear waters below, you seem suspended in time and space. But then you notice that there is movement all around. A brown pelican glides overhead then suddenly wheels and crashes into the water to gather its next meal. Maybe you'll see a sea turtle skimming above the seagrasses, or a manatee grazing. Life surrounds you.
Biscayne Bay is a shallow estuary, a place where freshwater from the land mixes with salt water from the sea and life abounds. It serves as a nursery where infant and juvenile marine life reside. Lush seagrass beds provide hiding places and food for a vast array of sea life. In fact approximately 70 percent of the area's recreationally and commercially important fishes, crustaceans, and shellfish spend a portion of their young lives in the bay's protective environment.
Protected from the ocean to the east by a chain of islands or keys and by the mainland to the west, the bay is one of the most productive ecosystems in the park. Fresh water flow brings nutrients from inland areas. Plants use these nutrients, along with energy from the sun, carbon dioxide, and water to produce food through photosynthesis. Some of the most important plants found in the bay are the seagrasses.
Seagrasses grow in lush beds throughout the bay wherever conditions are favorable and there is enough bottom sediment for the seagrasses to take root. Like the grasses of your lawn at home, seagrasses are flowering plants. They have roots, stems, and flowers. They produce oxygen. And without exceptionally clear water that allows the sunlight to reach them, seagrasses will die off just as your lawn at home would if it were deprived of sunlight.
There are three major types of seagrasses found in the bay. Shoal-grass, Halodule wrightii, is an early colonizer of disturbed areas and usually grows in water too shallow for other species.
Turtle-grass, Thalassia testudinum, the most common seagrass in the park, has wide leaf blades and a deep root structure, and forms most of the large, lush seagrass meadows found in the park.
Manatee-grass, Syringodium filiforme, is easily recognizable because its leaves are cylindrical.
The areas where there is not enough sediment on the bottom to allow seagrasses to take root are called the hardbottom. Although the hardbottom areas may appear barren and lifeless, this is not true. They are home to soft corals, sponges, and numerous other invertebrates (including the tasty spiny lobster which finds food and shelter in the hardbottom).
South Florida's beautiful weather almost demands that time should be spent outdoors. The bay is no exception and is a wonderful place for recreation, from boating and fishing to snorkeling, swimming, and water skiing. The bay is enjoyed by all. Relative ease and location of boat launches encourages the ever-increasing boating population to enjoy the sporting and recreational aspects of the bay. But the bay's resources, especially its lush seagrass beds, are threatened. Only through care and foresight by our visitors and our neighbors can the bay continue to support all the diverse uses currently enjoyed.
information provided by National Park Service