COMPARATIVE EFFECTS OF BEACH MANAGEMENT POLICY ALTERNATIVES UPON FISHES OF SOUTHEAST FLORIDA

To examine the effects of differing beach management alternatives upon coastal fishes, an ecological risk assessment framework was assembled using retrospective and prospective analyses of projects in southeast Florida. Over 55 dredge projects in the last 40 yr have dredged and filled approximately 53x10⁶ yd³ of mid-shelf sediments along the shorelines between Dade and Martin Counties, a distance of less than 150 miles. Over 100 acres of nearshore reefs are proposed for burial in several current projects. At least 80x10⁶ yd³ of additional sediments are planned for dredging within the same corridor in the next 50 yr. Over 515 species of invertebrates and fishes are now known from nearshore hardbottom areas affected by these projects. Outside of lagoons, nearshore hardbottom areas are the primary natural structures in shallow waters and have nursery value for at least 30 species of fishes. Dredge-and-fill effects upon fishes or invertebrates have been examined by few peer-reviewed publications with replicated sampling before and after impacts, control sites, or adequate sample sizes. The interactive effects of repetitive dredging and sediment resuspension may cumulatively reduce local biological production, yet are also unexamined. Common assumptions that large dredge-and-fill projects in southeast Florida are environmentally benign may be premature. The effects of ten engineering alternatives were examined using multicriteria decision support systems. Combinations of several options in addition to dredging (for example, increased use of inlet sand bypassing plants) were identified as technically and politically feasible for enhanced environmental management of Florida's beach systems.