Process_Description:
Source_Data_Process_Steps (from source metadata)
Broward Benthic:
For the production of the final maps, a bottom up approach was taken. The high resolution LADS bathymetry was used to map reef geomorphology, acoustic data (QTC and Echoplus) were used to aid in defining the geomorphologic features into habitat types, and a waterproof drop video camera from a boat was used as groundtruthing to confirm substrate type. The shallow inshore seafloor from the 0m to -6m contour was mapped using a combination of assimilated data types including aerial photography and high-resolution bathymetry and the deeper seafloor habitats, from the -6m to the -35m contour, were mapped using mostly high-resolution bathymetry and acoustic ground discrimination. The result produced a seamless GIS benthic habitat classification of the entire nearshore reef system in Broward County. The final map polygons conformed to the NOAA hierarchical classification scheme used in Puerto Rico and the U.S. Virgin Islands NOAA Technical Memorandum NOS NCCOS CCMA 152 with some modification. All data were mapped in ArcGIS9 and polygons were drawn at a scale of 1:6000 with a one acre minimum mapping unit.
Palm Beach Benthic:
For the production of the Phase I maps, a bottom-up approach was taken (Hewitt et al., 2004). The high resolution LADS bathymetry was used to map reef geomorphology; acoustic data from the ground-discrimination surveys were used to aid definition of the geomorphologic features into habitat types; and a waterproof drop video camera from a boat was used as groundtruthing tool to confirm substrate type. The entire area mapped was roughly 254 square-kilometers. The shallow inshore seafloor from the ~0m to -6m contour was mapped using a combination of assimilated data types including aerial photography and high-resolution bathymetry and the deeper seafloor habitats, from the -6m to the -35m contour, were mapped using high-resolution LADS bathymetry and acoustic ground discrimination. The result produced a seamless GIS benthic habitat classification of the entire nearshore reef system in Palm Beach County.
Similar to the Broward habitat mapping effort (Report on DEP Agreement No G0057, NOAA Award NA160Z2440), the final map polygons conformed to the NOAA hierarchical classification scheme used in Puerto Rico and the U.S. Virgin Islands NOAA Technical Memorandum NOS NCCOS CCMA 152 (Kendall et al., 2001), with some modification. All data were mapped in ArcGIS 9x and polygons were drawn at a scale of 1:6000 with a one acre minimum mapping unit (MMU).
South Florida Benthic:
Winter 1991/92, NOAA's Coastal Services Center's Coastal Change and Analysis Program (C-CAP) and the state of Florida commissioned the National Ocean Service's Photogrammetry Unit, the National Geodetic Survey, to acquire conventional color metric aerial photography of Florida Bay suitable for interpretation of photic benthic habitats (scale 1:48,000). Additional photography was acquired by NGS in 1995 to cover areas missed. The imagery was collected according to stringent parameters detailed in the C-CAP protocol. The resulting image file was rectified using Erdas Imagine Software. The interpreted polygon habitats were digitized into ARC coverage from the rectified files using Erdas Imagine software's vector module. In 1999, the final edits and quality control of the habitat polygons were completed. The coverage and shoreline were edge matched to the benthic habitats of the Florida Keys atlas to complete the coverage, as the dates of photography, methodology and classification system used were the same.
Data generated by FWRI and NOAA staff, along with ecologists contracted by NOAA and FWRI. The aerial photographs used in producing the maps were taken and digitally compiled by NOAA's NGS staff. Contracted ecologists and FWRI staff developed the classification scheme. FKNMS staff provided support for the photo interpretation, delineation, and ground-truthing activities and for reviewing the benthic classifications. NGS staff digitally compiled the photographic information. Staff from Strategic Environmental Assessments (SEA) division of ORCA converted the NGS digital files into a Geographic Information System (GIS) and then performed QA/QC on those files. Staff from both FWRI and NOAA's Ocean Resources Conservation and Assessment (ORCA), which is now part of the National Ocean Service, designed and produced the atlas.
Aerial Photography Natural-color aerial photographs of the Florida Keys region were taken by NOAA's Remote Sensing Division during flights made from December 1991 through April 1992. A Wild RC-30 camera mounted in a Cessna Citation II Fanjet aircraft was used. The source photography had a nominal photo scale of 1:48,000 (1 cm = 480 m). Each photograph covered an area of approximately 160 km2. An 80% endlap and 60% sidelap of adjacent photographs ensured that coverage would be complete and that an adequate number of reference locations would be present for photogrammetric measurements. Approximately 450 photos provided monoscopic coverage and were used to delineate benthic habitats.
Establishing a Habitat-Classification Scheme Two recognized ecologists, both with local knowledge of the Florida Keys and extensive expertise in marine habitats, along with FWRI staff, developed the hierarchical classification scheme used in this atlas. The habitat-classification scheme is composed of 24 classes of benthic communities in 4 major habitat categories: corals, seagrasses, hardbottom, and bare substrate. Dredge zones, banks, and restoration areas located within these communities are also denoted.
Photointerpretation Photos were interpreted by the two ecologists and FWRI staff. They determined and then delineated the types of benthic habitats found in the aerial photos. The minimum habitat area delineated was 0.5 ha. However, patch reefs (herein considered part of the coral reef benthic habitat) of less than 0.5 ha were delineated as points. Ground-truthing was conducted to verify that benthic habitats were properly identified on the aerial photographs. Researchers were able to ground truth most benthic communities while snorkeling; scuba gear enabled them to ground truth for those communities located in deeper or turbid waters. Field information about the benthic habitat and site GPS locations was recorded. The ecologists and FWRI staff reviewed photos for content and accuracy and then sent them to NOAA for digital compilation.
Digital Compilation of Aerial Photographs NGS cartographers inspected each photograph for completeness of delineations, photo discrepancies, and areas of turbidity. Cartographers used a stereographic analytical plotter with NOAA's in-house software to digitize and label the benthic communities and shoreline features seen on the aerial photos. In many cases, the cartographers were able to provide additional detail because of the three-dimensional views permitted by the analytical plotter. The compiled data were checked by NGS staff.
Quality Control - Data were reviewed in three phases: 1) a review of digital data to ensure line and attribute completeness, 2) a comparison between the 1:48,000-scale maps of the compiled data and the original source photos, and 3) a comparison between the 1:24,000-scale maps of the compiled data and the original delineated photos to determine the positional accuracy of polygonal shapes and attributes.
Positional Accuracy Standards - Aerial photographs used to generate the digital data for the maps in this atlas were taken between December 1991 and April of 1992. Thus, the atlas represents the distribution of benthic habitats in the Keys over this time period. The horizontal accuracy of well-defined points (clearly identifiable, immobile objects such as the tops of radio towers or the corners of wharves) is within 2 m. The horizontal accuracy of continuous data (e.g., benthic habitats) ranges from 5 to 10 m, depending on the habitat class. Certain benthic features, such as patch reefs and spur-and-groove reefs, have a horizontal accuracy of 5 m. These habitats are composed of massive rock and coral formations that are stable in position over time and are resistant to all but the most powerful physical forces. Coral reefs, once established, tend to remain for decades or centuries.
Other habitats-such as seagrass beds, hardbottom communities, and bare substrate-are less stable. These benthic features are positionally accurate to within 10 m. Physical factors such as water currents and hurricanes and biological factors such as seasonal growth and die-off affect the distribution and stability of these benthic habitats along the ocean's floor. Plant densities within seagrass communities may increase or decrease over a period of months or years. Hardbottom habitats may become covered by sediment and then by seagrasses.
GIS Data Layers To ensure that the digital data sets in this atlas were accurate in position and attribution, SEA staff used a series of data-translation and topology-construction steps while incorporating the data into a GIS, a sophisticated computer mapping and analysis software. All the individual GIS digital data sets were then combined to form several regional mosaics. Each region's data set was sent to FWRI for final quality control and assembly. FWRI inspected these data sets to ensure that no errors remained. The regional data sets were then joined together to make an FKNMS-wide, benthic-habitat data set. The resulting data set was inspected one last time, with particular scrutiny paid to the regions of overlap, where errors would most likely occur. The delineated aerial photos were referred to at every step of this process.
Summer 2001 Florida Bay area was added using similar methodology in 2001
Southwest Florida coast bottom type:
FWRI digitized bottom types off NOAA charts (charts at a 1:100,000 scale) in ArcInfo at a 1:100,000 scale.
Florida Middle Grounds 1979:
Polygons were digitized from the 1979 Seafloor Roughness Map (Texas A & M Department of Oceanography).
The paper map has experienced shrinkage, and the RMS error when digitizing was between .006 and .008 (roughly 40-50 feet).