Data Management Plan

Habitat maps were created as part of a larger ecological assessment conducted by NOAA's National Ocean Service (NOS), Biogeography Branch, for Salt River Bay National Historic Park and Ecological Preserve (National Park Service). Aerial photographs were obtained for 1971 and 1977 from the National Geodetic Survey, and were orthorectified by the Biogeography Branch. A classification scheme was set up with 20 benthic habitat types, 19 land cover types, and 13 mangrove habitat types. For this map of seagrass and mangrove habitats during the 1970's only the 3 seagrass, and 14 mangrove classification categories were used. These were mapped directly into a GIS system through visual interpretation of orthorectified aerial photographs.

Process Steps:

• 2004-01-01 00:00:00 - Benthic habitat maps were digitized by delineating habitat boundaries from georeferenced imagery loaded into ArcView 3.2 GIS software with the Image Analysis extension and NOAA Coral Reef Habitat Digitizing extensions both activated. On-screen digitizing was conducted with the minimum mapping unit (MMU) set to 100 square meters and the image scale at 1:1500. During the digitizing process, image stretches and manipulation of image contrast, brightness and color balance were performed in the ArcView Image Analysis Extension to enhance features in the processed imagery. Additional collateral information, including previously completed habitat maps, NOS nautical charts, and other descriptive references dealing with benthic and coastal habitats of Salt River National Historic Park and Ecological Preserve was used to assist with image interpretation. A first draft map was completed and features in the imagery where uncertainties existed, due to confusing or difficult to interpret signatures, were identified for future ground validation effort. Since maps were based on historical imagery that didn't necessarily reflect current ground condition, similar signatures were identified in year 2000 aerial photographs. An ArcView GIS point theme was generated with points positioned on the features of uncertain habitat type or along transects through gradients between habitat types. The GIS points were converted to GPS waypoints, and were visited for on the ground habitat validation. Benthic habitat characterization was conducted at each site by snorkeling, free diving, or via observations from the surface where water depth and clarity permitted. Mangrove habitat characterization was conducted by driving, kayaking or hiking to points and visually identifying mangrove type and cover. GPS data was collected at each location, and site ID, depth, habitat type, and the method used to make the assessment were recorded. The ground validation data was incorporated into the second draft of each map.