success for some species that use the Bay as a juvenile nursery habitat also was reported during that period.

Florida Bay is linked intimately to the Everglades. Some of the water draining from the Everglades through Taylor Slough/Craighead Basin flows directly into Florida Bay, supplying it with freshwater runoff. Additional water from the Everglades appears to reach the Bay indirectly after it is discharged from Shark River Slough to the northwest and mixes with inshore shelf water. The Everglades has been altered greatly during the past century, including the construction of canals, levees, pumps and control structures, and conversion of land to cities and farms. This has led to water quality degradation, nutrient enrichment, loss of wetlands, and landscape fragmentation in various parts of the Everglades.

Florida Bay is included in the CERP through the Florida Bay & Florida Keys Feasibility Study (FBFKFS), which is to be conducted to assess the current conditions of the Bay and to determine the modifications needed to restore it. Research in Florida Bay is carried out by many academic and governmental institutions. One of the most important of these is the Florida Bay and Adjacent Marine Systems Science Program, formed by state and federal agencies having regulatory and/or scientific interest in this region.

Potential Effects of the CERP on Florida Bay

An important assumption often made by scientists and managers associated with the CERP, and by the public, is that the increased flows of water deemed necessary to restore habitats in the Everglades also will contribute to the restoration and enhancement of Florida Bay. This is because increasing frequency, severity, and duration of hypersaline conditions in parts of the Bay, and a decrease in the spatial and temporal extent of estuarine conditions, are thought by some scientists to have been major factors leading to a dramatic die-off of turtle grass around 1987.

For a number of reasons, these assumptions may not be correct. First, the evidence linking the turtle grass die-off to hypersalinity is equivocal and there is little agreement within the Florida Bay research community that this was the causative factor of the die-off. Second, direct, fresh surface water flow into northern Florida Bay (i.e., via Taylor Slough and Craighead Basin, etc.) is predicted to be about the same in 2050 relative to the current condition whether the CERP is implemented or not. If this is correct, there will be little effect on salinities in central Florida Bay and no relief to any associated ecological problems that may exist. On the other hand, recent research suggests that some percentage of the proposed significant increase in fresh surface water flow through Shark River Slough will ultimately reach the central Bay by passing across the western boundary of the Bay after mixing with shelf water.

It also is not clear how, or if, the CERP will affect the magnitude of groundwater fluxes to Florida Bay. At present, the freshwater-saltwater interface in the surficial aquifer system is inland of the Bay. However, if the CERP raises overall water levels in the southern Everglades, this interface may be pushed southward over time toward Florida Bay in certain areas along the coast, and could result in fresh groundwater discharge directly to the Bay. Even if the direct discharge remains saline, changes in the quantity of groundwater inputs may be important to nutrient fluxes in some parts of the Bay.

In addition to the uncertainties concerning the amount of fresh surface and groundwater that may enter Florida Bay because of the CERP, it is possible that an increase in water would also bring an increase in nutrient inputs. If this is the case, the biological and ecological effects of such an increase in nutrient loadings are unclear. While there is a broad scientific consensus that the growth of phytoplankton of eastern Florida Bay and seagrasses throughout the bay is phosphorus-limited, there is less agreement about the relative importance of nitrogen and phosphorus in limiting the growth of phytoplankton and macroalgae in the central and western Bay.

Florida Bay phytoplankton blooms appear to develop where nitrogen-enriched water from the eastern Bay and from land drainage mixes with relatively phosphorus-rich water of the western/central Bay. Thus, the higher natural or anthropogenic loadings of nitrogen and, perhaps, phosphorus that may

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement