The Importance Of Estuaries
Sanibel’s wildlife is both diverse and dense. The subtropical sights and sounds of water fowl, reptiles, and manatees are the result of the changing nature of estuaries, which create the ecosystems necessary to provide food and shelter for so many different animals and plants. It is a good idea to familiarize yourself with the contributions of estuaries before venturing out on your wilderness adventure so you can fully appreciate the impact Sanibel’s estuary has on the island’s beauty.
An estuary is a coastal body of water that results when a fresh-water river(s) flows into a semi-enclosed body of salt-water, bringing with it (them) large amounts of sedimentation and silt. The rising and lowering levels of estuary water throughout a calendar year create different environments for all types of plants and animals who make their homes in estuaries for part of the year. Estuaries are known for being biological hot spots, where life is constantly in a state of flux and teaming with activity. A large variety of animals can benefit from the estuary without pushing each other out because they have all evolved differing ways of benefiting from the estuary without encroaching on each other’s supply of food or shelter.
In Florida, the winter is marked by dryness, and the summer by heavy rainfall. In fact, about 70% of Florida’s annual rainfall occurs during its summer months. This is surprising to some people who consider Florida to be an area of the country that doesn’t experience changing seasons. In the spring, Sanibel’s estuary provides shelter and food for birds returning north from their winter hiatus in the south, as well as a heavily populated mating ground. These same birds will return again in the fall as the return to the south across North America. Manatees return to the estuary waters from their warm-water winter shelters in the spring and can be spotted bobbing up and down along the northern shore of the island and in the bay. Schools of fish alternately leave and return depending on their spawning cycle. Estuaries provide tiny fish and crustaceans as food for birds as well as larger fish and reptiles, and each animal has evolved its own way of hunting food that does not infringe on the food supply of its estuary neighbors. Estuaries also make a large contribution in providing the proper soil conditions for varying forms of plant life.
The importance of Sanibel’s estuary cannot be overemphasized because it accounts for so much of the natural beauty of the island and sets her apart from other vacation spots in the U.S. Unfortunately, estuaries are also one of the most threatened ecosystems because of the growth and development occurring along U.S. coastlines as more people retire to coastal climates and purchase vacation getaways.