Florida Bay Benthic Cover 1995

NOAA Benthic Data Hub Registry

Conventional color metric aerial photographic diapositives (1:48,000) flown by NGS 1991,1992 and 1995 of Florida Bay, Florida

Benthic Habitats: Contracted ecologists and Florida Marine Research Institute (FRMI) staff developed the classification scheme. The ecologists and FMRI staff participated in ground-truthing, classification, and review of the benthic classifications. The C-CAP staff made digital compilations of the photographic information and created digital map layers in a Geographic Information System (GIS).

Aerial Photography: True color aerial photographs of Florida Bay were acquired by National Oceanic and Atmospheric Administration's Remote Sensing Division during overflights occurring from December 1991 through March 1992. Due to glare and turbidity in certain areas, additional photography was acquired during 1995. A Wild RC-30 camera mounted in a Cessna Citation II Fanjet aircraft was used to acquire the 1:48,000 (1 cm =480 m) source photography. Each photograph covered approximately 160 square kilometers. An 80 percent endlap and 60 percent sidelap between adjacent photographs ensured both complete coverage and the presence of adequate reference locations necessary for determining positional accuracy. Approximately 80 photos provided monoscopic coverage and were used to delineate benthic habitats.

Establishing a Habitat Classification Scheme: Two recognized ecologists, both with local knowledge of Florida Bay and extensive expertise in marine habitats, were responsible for interpreting and delineating the benthic communities seen on the aerial photographs. These two ecologists, along with the FMRI staff, developed the hierarchical classification scheme used for this coverage. The habitat classification scheme was composed of 24 benthic communities in four major habitat categories: corals, seagrasses, hardbottom, and bare substrate. Special modifiers were attached to the classes to denote dredge zones, banks, and restoration areas.

Photointerpretation: The ecologists and FMRI staff interpreted and then delineated benthic habitats on the aerial photos. The minimum habitat area delineated was 0.5 hectares. Ground truthing was conducted to verify that benthic habitats seen in the water were properly identified on aerial photographs. Researchers were able to conduct most ground truthing of benthic communities while snorkeling. Field information about the benthic habitat and site GPS locations were recorded. The completed photos were reviewed for content and accuracy by the ecologists and FMRI staff and then sent to C-CAP staff for digital compilation.

Digital Compilation of Aerial Photographs: The C-CAP staff inspected each photograph for completeness of delineations, photograph discrepancies, and areas of turbidity. The aerial photographs, with the interpreted acetates attached, were scanned using a photogrammetric quality scanner (AGFA Horizon Plus) at a resolution of 600 dpi, resulting in a pixel resolution of 2.03 meters. The resulting image field was rectified interpolation bilinear (second order) using ground control points drawn from 1 meter color digital orthophotos of Florida Bay. The southern edge of the Florida Bay data set was edge matched to the Benthic Habitats of the Florida Keys Atlas. The rectification and digitization was completed utilizing the ERDAS Imagine software package.

Quality Control: A review of the data was conducted in two phases: 1) an on-line review to ensure line and attribute completeness, comparison to the ecologists' delineations, and positional accuracy; and 2) a review of 1:48,000 scale maps of the compiled data against the original source photos.

The data were converted from a single ESRI polygon data set classified according to the System for Classifying Habitats in Estuarine and Marine Environments (SCHEME) to the Coastal and Marine Ecological Classification Standard (CMECS) 2012 format. This produced separate biotic, geoform, and substrate feature layers from the original input benthic habitat dataset. Each of the three feature layers contain respective CMECS biotic, geoform, and substrate component attributes where an "Equal" or "Nearly Equal" SCHEME value was present in the original data. Polygons for which no biotic, geoform, or substrate information was present have been removed. No other changes to the original polygon boundaries or any other alterations of the original SCHEME data were made during this process.

Standardized common design elements, cleaned up field content, repaired geometry, and projected to NAD83.