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

Dealing with green tides on Brittany and Florida coasts.

communication oral

Green tides on the Brittany coasts.

For over a decade the European Commission has funded the programs aimed at examining the problems of algae production, their utilization and green tides. COST and BRIDGE have led to publication of two volumes surveying the situation, principally on the Atlantic and Mediterranean coasts of Europe. Two presenters of this paper are members of the team and co-authors of the books. The volumes center on Europe, and the presenters have been principally concerned with the eutrophication and the bioconversion of seaweeds. Research has led to a series of proposals to alleviate the accumulation of stranded algae, mostly Ulva, and their disposal or, at least, their partial utilization in agriculture, industry and even energy production. The paper reviews and summarizes their conclusions, several not yet published, putting an accent on the methanization, and draws a parallel with a prevailing situation in south-eastern Florida. Related topics include: anaerobic digestion of Ulva, bioconversion of algae, composting of Ulva, management of eutrophication, and the “seaweeds” programs of the European Commission

New approaches to sediment management on the inner continental shelf offshore Coastal Louisiana

Coastal restoration in Louisiana requires clean sands for beach and dune restoration, whereas mixed sediments are required to rebuild marshes. The Louisiana coastal erosion problem is especially dire because it occurs on several fronts with the narrowing and overtopping of barrier islands and loss of back barrier bay and interior marshlands. Coastal restoration efforts in Louisiana depend on emplacement of sediment to build up barrier island and deltaic systems. Discovery of usable sediment is thus a vital factor in restoration efforts because up to 80 of some restoration project budgets can be allocated to exploration, exploitation, and emplacement of sediment. Because this cost is directly proportional to the distance of borrow sources from the project area, the cost-effectiveness of barrier island restoration and marsh creation depends on locating sufficient sediment volumes that are suitable for placement on beaches and dunes and for creating marshes. The restoration of Louisiana\u27s barrier islands and the creation of coastal marshes are critically dependent on the availability of suitable modern marine and riverine sediments and other buried fluvio-deltaic deposits. It is thus imperative that a comprehensive sediment management plan be developed to systematically and efficiently identify and allocate suitable sediment resources. At present, coastal and barrier island restoration projects are included in regional planning efforts, and the restoration project is decided before sediment sources are considered. The new approach proposed here is based on planning projects around locations of dredgeable sedimentary deposits in order to optimize sediment resources. Centralization of voluminous historical geoscientific and oil and gas infrastructure data is being accommodated in a new data management system called the Louisiana Sand Resource Database (LASARD). Managing sediment resources more strategically optimizes regional planning strategies and reduces construction costs. The Louisiana Sediment Management Plan (LASMP) conceptualizes systematic planning and better coordination of essential components of the huge restoration and protection effort currently undertaken in Louisiana. © Coastal Education & Research Foundation 2010

Effect of Hurricane Ivan on Coastal Dunes of Santa Rosa Barrier Island, Florida: Characterized on the Basis of Pre- and Poststorm LIDAR Surveys

Santa Rosa Island, situated along the northwestern Florida coast facing the Gulf of Mexico, is an 85-km-long wave-dominated low-lying barrier island with well-developed incipient and established dunes. In this paper, we examine the regional-scale effect on coastal dunes by a strong category 3 hurricane, Ivan, through comparison of pre- and poststorm airborne LIDAR (light detecting and ranging) surveys. On the basis of pre-Ivan LIDAR survey data, the elevation of the berm and back beach is typically 2.0 m above MSL (mean sea level). Incipient dunes range from 2.5 to 10 m above MSL, or 0.5 to 8.0 m above the surrounding beach. The hummocky dunes that developed over relic washover platforms are typically less than 4.0 m above MSL. The densely vegetated, established dune fields are composed of dunes less than 7.0 m high and intradune wetlands lying at less than 1.0 m above MSL. The entire island was severely affected by Ivan, which made landfall about 45 km to the west in September 2004. The landscape was substantially changed by Ivan. Over 70% of the incipient and hummocky dunes were destroyed, and a large portion of the low-lying wetlands was covered by washover. The degree of storm-induced morphology change depends not only on the intensity and duration of the storm but also on the antecedent morphological characteristics of the barrier island. Comparison of pre- and post-Ivan cross-island LIDAR profiles indicates that at most locations, more sand was eroded from the subaerial portion of the barrier island (e.g., beach and dune) than was deposited as washover terraces and lobes. This suggests a net sand loss to the offshore region. Evidence of sand moving alongshore related to the oblique orientation of the dunes was also identified. Under inundation regime, the subaerial sediment deficit could be accounted for by subaqueous sedimentation into the back-barrier bay