Benthic habitat maps of the nearshore marine environment of St. John, U.S. Virgin Islands were created by visual interpretation of remotely sensed imagery. The objective of this effort, conducted by NOAA's Center for Coastal Monitoring and Assessment - Biogeography Branch in partnership with the U.S. National Park Service (NPS), was to provide spatially-explicit information on the habitat types, biological cover and live coral cover of St. John's coral reef ecosystem. The data described herein represent ground validation (GV) sites explored by NOAA field scientists to further refine habitat map classification.
The purpose of this survey data was to investigate areas of imagery where uncertainties existed on the photo interpreter's behalf during the decision making process of benthic habitat classification in St. John. This information was incorporated into a fine-scale assessment of the status, abundance, and distribution of marine habitats of St. John. The NOAA effort provides the U.S. National Park Service with increased technical capacity for ocean exploration, management, and stewardship. Direct implications to management measures include evaluation of management efficacy, a spatial framework for improved monitoring sampling design, improved assessment of human-use impacts, and marine spatial planning to support alternative marine protected area boundary alternatives.
The creation of high-quality benthic habitat maps required extensive field work to enhance accuracies of habitat attribution and, to a lesser degree, habitat delineation. Data were collected on 444 ground validation sites over a two-week field mission from January 5-16, 2009 aboard U.S. National Park Service small research vessels.
ground condition
Not for navigation.
1305 East West Highway
The points in this thematic data layer were acquired by GPS data using a Trimble GeoXT receiver with a customized data dictionary designed to reflect the habitat classification scheme described in "Benthic Habitats of St. John, U.S. Virgin Islands" (Zitello et al. 2009). All habitat determinations were made in the field by trained NOAA scientists, recorded in the GPS data logger and seamlessly transferred to ArcGIS shapefiles using Trimble Pathfinder Office software. Attributes are all expected to be correct.
Data points with accompanying attribute information were collected with mapping-grade GPS receivers. The data were post processed for differential correction to the Continually Operating Reference System (CORS) station at St. Thomas, U.S. Virgin Islands (VITH). Site information was recorded in the field both in a data dictionary within the GPS receiver and on waterproof field sheets. A comparison between soft and hard copy data records were completed to ensure attribute collection consistency. Furthermore, underwater video was recorded at each site to maintain a record of habitat condition. This video was reviewed by NOAA staff in the office to ensure correct habitat attribution was made in the field. All errors were identified through these quality assurance techniques and corrected. This file is believed to be logically consistent.
444 field positions were occupied and habitat characterizations were conducted for ground validation during this work. These data were included in the mapping dataset as a GIS layer and the draft habitat map was edited based on this ground condition. All areas where uncertainty existed on the part of the photo interpreter during habitat delineation were investigated in the field. All data were collected and integrated into the mapped products as planned.
The true positional accuracy of individual epics was determined to be within 1 m for 96% of the logged points. For each survey site, individual epics were averaged to generate a mean GPS point for each location.
GPS data, which were originally recorded as code-phase signals in Trimble SSF format, were differentially post-processed to the Continually Operating Reference System (CORS) station at St. Thomas, U.S. Virgin Islands (VITH).
A first draft benthic habitat map was generated by delineating all features that could be identified by visual inspection of the remotely sensed imagery. During the creation of this first draft, the interpreter placed discrete points on the map that were difficult to distinguish and that warranted further field investigation. These sites were labeled as "ground validation" (GV) positions. Process_Date: 2008-2009
NOAA field scientists explored the ground validation locations with a suite of assessment techniques depending on the conditions at each site. A combination of underwater video (primary method), free diving, snorkeling and surface observations were used to survey the ecological characteristics at each location. At the start of every morning, the boat captain selected a general region to begin the day's work. Navigating to field locations was accomplished using a Garmin GPS 76 device with the uploaded GV site coordinates. The boat captain maneuvered the vessel to within 5 m of the target location and made every effort to maintain that location without jeopardizing crew and equipment safety. Once on site, NOAA scientists would simultaneously deploy a SeaViewer Sea-Drop 950 camera and begin logging a waypoint on a Trimble GeoXT GPS receiver.While the video camera was capturing bottom imagery, an observer viewed the video real-time on a Panasonic Toughbook aboard the survey vessel. They categorized each site according to the levels of the habitat classification scheme: major and detailed geomorphological structure, major biological cover, percent major biological cover and percent coral cover. Data was entered into a custom data dictionary generated in Trimble Pathfinder Office software and loaded onto the Trimble data logger.
Trimble Pathfinder Office software was used to post process and differentially correct the raw GPS data to the Continually Operating Reference System (CORS) station at St. Thomas, U.S. Virgin Islands (VITH).
Precisely positioned GPS positions and its associated classification data were viewed in a GIS to enhance the accuracy of the draft benthic habitat map. Polygon boundaries and habitat classifications were revised where field data necessitated changes.
Internal feature number.
ESRI
Feature geometry.
Unique identifier for each ground validation site
NOAA
Date of site visit and data collection
Time of site visit and data collection
Purpose of data collection
Ground Validation
Unknown
Method used to obtain habitat characterization information
SeaViewer Sea-Drop 950 underwater camera
NOAA scientist visually characterized habitat by free diving or surface swimming with a mask and snorkel
Any other assessment technique, including inspection from the vessel deck with a "look bucket" or binoculars
Major Geomorphological Structure
Refer to Chapter 1: Benthic Habitat Classification Scheme of "Benthic Habitats of St. John, U.S. Virgin Islands" (Zitello et al. 2009)
Detailed Geomorphological Structure
Major Biological Cover
Percent Patchiness of Major Biological Cover
Percent Cover of Live Coral
Specific details of the attributes and values therein can be found in Chapter 1: Benthic Habitat Classification Scheme of "Benthic Habitats of St. John, U.S. Virgin Islands" (Zitello et al. 2009).
Zitello, A.G., L.J. Bauer, T.A. Battista, P.W. Mueller and M.S. Kendall. 2009. Benthic Habitats of St. John, U.S. Virgin Islands. NOAA Technical Memorandum NOS NCCOS 96. 50 pp.
The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) is publishing this data on their website. NCCOS Biogeography Branch does not guarantee the accuracy of the geographic features or attributes. Please see the written report and metadata records for each data set for complete information on the source, limitations, and proper use.
Contact NOAA for distribution options (see Distributor).
