Spatial Analyses of Benthic Habitats to Define Coral Reef Ecosystem Regions and Potential Biogeographic Boundaries along a Latitudinal Gradient

Marine organism diversity typically attenuates latitudinally from tropical to colder climate regimes. Since the distribution of many marine species relates to certain habitats and depth regimes, mapping data provide valuable information in the absence of detailed ecological data that can be used to identify and spatially quantify smaller scale (10 s km) coral reef ecosystem regions and potential physical biogeographic barriers. This study focused on the southeast Florida coast due to a recognized, but understudied, tropical to subtropical biogeographic gradient. GIS spatial analyses were conducted on recent, accurate, shallow-water (0–30 m) benthic habitat maps to identify and quantify specific regions along the coast that were statistically distinct in the number and amount of major benthic habitat types. Habitat type and width were measured for 209 evenly-spaced cross-shelf transects. Evaluation of groupings from a cluster analysis at 75% similarity yielded five distinct regions. The number of benthic habitats and their area, width, distance from shore, distance from each other, and LIDAR depths were calculated in GIS and examined to determine regional statistical differences. The number of benthic habitats decreased with increasing latitude from 9 in the south to 4 in the north and many of the habitat metrics statistically differed between regions. Three potential biogeographic barriers were found at the Boca, Hillsboro, and Biscayne boundaries, where specific shallow-water habitats were absent further north; Middle Reef, Inner Reef, and oceanic seagrass beds respectively. The Bahamas Fault Zone boundary was also noted where changes in coastal morphologies occurred that could relate to subtle ecological changes. The analyses defined regions on a smaller scale more appropriate to regional management decisions, hence strengthening marine conservation planning with an objective, scientific foundation for decision making. They provide a framework for similar regional analyses elsewhere

Potential natural environments based on pedological properties in the coastal conurbation of subtropical southeast Florida

Much of the coastal southeast Florida Peninsula is heavily urbanized, and many native environments have been destroyed or severely affected by urbanization. In an attempt to reconstruct potential natural environments, soil properties were used as a basis for recognizing prior landscapes. Pedological associations were adopted because they provided landscape features that were least modified by urbanization and they could be used as a unifying basis for categorization of native coastal environments. A geographic information system analysis ring was used for querying coverages for soil distribution patterns, vegetation, hydrology (drainage), topography, and geology. By simultaneously generalizing and recombining soil survey data, land use cover types, topography, and hydrology, it was possible to identify recurring patterns of soils, landforms, and vegetation. Results of this analysis produced 13 land systems with 25 subunits that included various types of lakebeds, tree islands, marshes, prairies, sloughs, sandplains, glades, marshlands, lagoons, estuaries, and beaches. The resulting map for potential natural environments in Palm Beach and Broward Counties complements conceptual ecological models for the Greater Florida Everglades Ecosystem, de-veloped for the Comprehensive Everglades Restoration Plan. The Australian land systems approach, as applied in this study, provides insight into coastal environments that lie outside of ecological models for mostly protected areas inland