At what lake in the area that has been covered by sea water at least seven times do nutrients quickly deteriorate?
A vast marshland could only have been formed due to the underlying rock formations in southern Florida. The floor of the Everglades formed between 25 million and 2 million years ago when the Florida peninsula was a shallow sea floor. The peninsula has been covered by sea water at least seven times since the earliest bedrock formation. The rock that makes up the Everglades floor was created as layers of calcium carbonate were compressed by ocean water, making limestone. Fossilized bryozoans and tiny shells, or ooids, make the limestone porous. Water is stored in the rock, sometimes from one year to the next. The length of time that a region in the Everglades remains flooded, called a hydroperiod, determines what particular soils and vegetation are present.
Shorter hydroperiods of three or four months promote the growth of periphyton: algae and other microscopic organisms covered with calcium carbonate crystals. Periphyton is the basic building block of marl, a calcitic mud. In areas with hydroperiods of longer than nine months, peat builds up over hundreds or thousands of years due to many generations of decaying plant matter. Peat and marl are considered nutrient-poor soils that foster the growth of specialized vegetation depending on the length of the regional hydroperiod.
Five types of peat appear in the Everglades system; each type supports a specific type of vegetation, such as sawgrass, tree islands, or custard apple trees. Peat buildup is possible because water prevents oxygen from quickly decomposing plant matter. Once peat buildup reaches the surface, oxygen reacts with the microorganisms to decay the peat rapidly in a process called subsidence. Initial attempts at developing agriculture near Lake Okeechobee were successful, but the nutrients in the peat quickly deteriorated by drying, and were broken down by bacteria in the soil. The dried peat burned or was degraded into carbon dioxide and water by microorganisms. Some homes built near early farms had to restructure their foundations on stilts as the peat deteriorated; other areas lost approximately 8 feet (2.4 m) of soil depth. Between the 1880s and 2005, an estimated 3.4 billion metric tons of soil has been lost in the Everglades due to oxidation. Most of that loss occurs in the Everglades Agricultural Area; the least amount of loss is found in Everglades National Park.
Okeechobee