Florida Bay is a triangular, tropical lagoon/bay which occupies a shallow, rocky trough between the relic, exposed barrier reefs of the Florida Keys and a series of mangrove-lined bays and sounds at the southern end of the Florida peninsula (Surface water improvement and management plan for the Everglades, 1992). The western side opens directly to the Gulf of Mexico. The bay is about 2200 km2 in total area, with 1800 km2 included within Everglades National Park (Tilmant, 1989; Robblee et al., 1991). Florida Bay is effectively divided into a series of basins by a complex network of anastomosing carbonate mud banks that restrict circulation (Sogard et al., 1989). Depths vary from only centimeters over the mud banks, to a few meters in the deeper basins.

Historically the bay has been described as varying between a positively functioning estuary and a tropical, hypersaline lagoon, depending up the season: a positively functioning estuary during periods of high rainfall (summer); a hypersaline lagoon when evaporation exceeds upland runoff and oceanic exchange (winter).

Due to the effects of water management the bay now functions more often as a hypersaline lagoon. Under pre-managed conditions, Florida Bay received its input of freshwater from sheet flow across the southern Everglades and Taylor Slough. In addition, freshwater flowed through Shark River Slough, into Whitewater Bay, and subsequently entered western Florida Bay via flow around Cape Sable (Fourqurean et al., 1993). Today, these areas, along with the C-111 canal, are still the major sources of freshwater inflow to coastal estuaries and Florida Bay. However, the current water management system has altered water delivery to the bay by constructing a series of canals, impounding water in the Water Conservation Areas, and diverting water eastward to urban areas and the Atlantic Ocean. Evidence from coral banding suggests that the overall volume of freshwater flow has been reduced by more than half in the past century (McIvor et al., 1994).

Currently, freshwater inflow to Florida Bay increases with the beginning of the rainy season in June from direct rainfall, surface flow and groundwater discharge (Mazzotti and Brandt, 1989). During normal rainy seasons, Florida Bay exhibits a pronounced gradient of salinity increasing from north to south across the entire bay. The causes of salinity patterns in Florida Bay include not only freshwater inflow but also circulation and flushing patterns. As mentioned above, the anastomosing shallow mud banks divide the bay into discrete basins. These banks act as barriers, effectively limiting water exchange between basins, particularly in interior sections of the bay. In addition, due to the absence of hurricanes for the last 32 years, both basins and banks undoubtedly have become shallower, further restricting circulation. Reduced circulation, when coupled with low freshwater inflow and high evaporation, leads to conditions of hypersalinity. In all but the years of highest rainfall, portions of Florida Bay, particularly in the central portion, have become hypersaline, with salinities greater than 35 parts per thousand (Fourqurean et al., 1993).

Florida Bay supports diverse biological communities that are interrelated in this complex ecosystem. The estuary contains two main types of marine (saltwater) habitats: mangrove areas and inshore marine areas (McIvor et al., 1994). Mangrove isles cover less than 2% of the area of the bay (Enos, 1989) and they will be the subject of the next network model. Inshore marine areas are of two types. The first are grass-bottomed areas, covered primarily with Thalassia testudium, Halodule wrightii and Syringodium filiforme. Seagrass meadows occupied more than 80% of the bottom of Florida Bay, prior to the die-off that began in 1987 (Zieman et al. 1989; Robblee et al. 1991).

They are among the most productive ecosystems in the marine environment, rivaling those of tropical rain forest and tidal marshes (Odum and Hoskin 1958, Zieman and Wetzel 1980, McRoy and Helffrich, 1977). The importance of seagrasses is due to several factors. These include their function as nursery areas containing high densities and diversities of fishes and invertebrates, which serve as feeding grounds for gamefish and waterfowl (Heck and Orth 1980), and which cycle carbon and other elements via detrital processes (Klug 1980). Seagrasses also provide stabilization for coastal sediments and support dense epiphytic communities (Klug, 1980). Epiphytes are sessile plants and animals that grow attached to their seagrass host (Harlin 1980) and are a significant component of the production of the system (Frankovick and Fourqurean 1998).

The second type of inshore marine area consists of hard-bottom calcium carbonate rock, overlain by a thin layer of carbonate sediment. This habitat is most common in the southern portion of the bay and is home to sponges, octocorals and macroalgal patches (Butler et al., 1992). Here the macroalgae, present also in seagrass beds, form large unattached masses, collectively known as drift algae. The species most representative of this environment are: Batophora oerstedi, Laurencia poitei and Acetabularia crenulata (Surface water improvement and management plan for the Everglades, 1992).

In recent years, significant deteriorations in water quality and biodiversity have been observed in the Bay. The cause of such degradation is not well understood, and it is most likely a combination of factors resulting, both anthropogenic and natural. Ever since the recent loss of turtle grass from the majority of the mud banks, turbidity and phytoplankton production have increased in the northern Bay. Further effects of loss of grasses include reduced recruitments of pink shrimp, snook, and redfish; lowered reproductive success of ospreys, great white herons, and roseate spoonbills; and shifts in the distributions of manatees, American crocodiles, and many of the wading birds that historically nested in the estuarine ecotonal area." (McIvor et al., 1994).

This series of web pages represents the data used for the network analysis of Florida Bay. The links in the menu on the left will guide you through the data that is laid out in a format that we hope will provide the viewer a better understanding of the system's dynamics. Each grouping of compartments contains several pages of tables, presenting the following data: biomasses and general flux rates, inputs to the compartments, outputs from the compartments, and individual compartment pages that detail the methods and sources we used to determine the values.

In order to remove confusion that was created by our original web design four years ago, we have used the same data values throughout the Florida Bay pages. In our previous effort, both our calculated numbers for individual parameters and the balanced numbers after the network was assembled appeared. From now on, as in this case, only the balanced numbers will be used. Additionally, we aim to have the entire data sets available on-line very soon. If you anticipate using a substantial amount of our data, we recommend that you download the appropriate data set, and use the values listed there. While we have striven for perfection in our presentation of the data, we realize that the sheer volume of data entries and tables almost guarantees that there are errors contained within. If you find any obvious discrepancy, please let us know so we may correct it immediately.

Lastly, we again recommend that you use the latest version of Netscape. Only the 4.0 versions of Netscape Navigator and Microsoft Internet Explorer support the formatting which has been used throughout this site.