SPECIAL SESSION: Marine/Coastal GIS & Acoustic Remote Sensing
organized by D. Wright (OrSt)
co-sponsored by the GIS and Coastal and Marine Geography Specialty GroupsAssociation of American Geographers Centennial Meeting
Denver, April 8, 2005, 10:00-11:40 a.m.This session focused on the principles, techniques, and applications of GIS in the marine and coastal realm, particularly the incorporation of acoustic remote sensing for benthic habitat characterization. It was a continuation of past sessions at AAG highlighting the various ways in which geographers are contributing to this evolving field of research. As such, additional, related topics for presentation and discussion included: (a) marine sanctuaries and protected areas; (b) marine and coastal data models and data structures; (c) web GIS for marine and coastal data; (d) questions in basic & applied marine science that have been derived, addressed and/or elucidated by GIS; and (e) integration of spatial analysis with policy, legal and/or economic issues, particularly in the coastal zone.
Described is the development of several analytical procedures for benthic habitat characterization from acoustic multibeam data. These include bathymetric position index (BPI) and rugosity. BPI is a quantitative parameter of signifying where a point is in the overall landscape. Many physical and biological processes acting on the landscape (or seascape) may be highly correlated with topographic position. In some cases the habitat of a particular species may be partially or wholly defined by the fact it is on a hilltop, valley bottom, exposed ridge, flat plain, upper or lower slope, and so on. Closely related is the calculation of rugosity, a measure of how rough or bumpy a surface is, or how convoluted and complex, often determined by a ratio of surface area to planar area. Analytical procedures to calculate these parameters have been developed for shallow bathymetry in a tropical coral reef environment, as an extension of the Ikonos-based classification scheme of the NOAA Biogeography Program, with an eye toward eventual benthic habitat characterization (given appropriate visual and acoustic groundtruthing data), as well as the enhancement of existing marine science curricula, and future management decisions regarding marine protected area designation. Issues of the distribution of data, procedures and related literature via the web are also discussed using recent work in American Samoa as examples; namely the American Samoa Benthic Terrain Viewer, the American Samoa Marine/Coastal Bibliographic Tool, and the Fagatele Bay National Marine Sanctuary GIS Archive.
Keywords: coastal/marine GIS, web GIS, terrain modeling, benthic habitat, coral reefs, seafloor mapping
Co-Authors:
Emily Lundblad, NOAA CRED and University of Hawaii, emily.lundblad@noaa.gov
Emily Larkin, Oregon State University larkine@geo.oregonstate.edu
Ron Rinehart, Oregon State University rineharr@onid.orst.edu
Joshua Murphy, NOAA Coastal Services Center joshua.murphy@noaa.gov
Ongoing has been the development of a systematic and robust methodology by which acoustic multibeam bathymetric data can be transformed into a classified product that is useful for coastal and marine resource managers, scientists and educators in American Samoa. GIS analyses for benthic terrain consider slope, aspect, rugosity, bathymetry, and bathymetric position index as factors. Based on this methodology Oregon State University and the NOAA Coastal Services Center have developed the Benthic Terrain Modeler (BTM), a new ArcGIS 8.x extension. The BTM also incorporates a scalable classification dictionary that can be used to maintain consistency across multiple levels of a seafloor mapping project. Included with the tool is a default classification schema that can be customized through one of the tool's steps or through direct editing of the classification dictionary file which is in the Extensible Mark-up Language (XML) format. The extension's wizard interface educates and guides the user through a series of analysis steps, resulting in a classified terrain that may be suitable for tying to benthic species distributions for the preparation of habitat maps. This methodology has been used to produce some of the first benthic terrain maps and 3-D visualizations for several coastal locations in American Samoa including the Fagatele Bay National Marine Sanctuary. Maps generated by the BTM have been further enhanced with data from towed-diver survey tracts and accuracy assessment points. Successful incorporation of these data sources will move beyond a purely geomorphological description of the benthoscape toward a biotic benthic community assemblage focused assessment.
Keywords: coastal/marine GIS, benthic habitat, coral reefs, seafloor mapping, spatial analysis, modeling
Co-Authors:
Dawn Wright, Oregon State University dawn@dusk.geo.orst.edu
Joshua Murphy, NOAA Coastal Services Center joshua.murphy@noaa.gov
Lori Cary-Kothera, NOAA Coastal Services Center lori.carey-kothera@noaa.gov
Emily Lundblad, NOAA CRED and University of Hawaii, emily.lundblad@noaa.gov
Emily Larkin, Oregon State University larkine@geo.oregonstate.edu
In March 2001 a unique study was conducted in the Monterey Bay National Marine Sanctuary, California that included a harbor dredging event into the framework of a dynamic coastal environment. The Santa Cruz Harbor dredged a small amount of fine grained sediment from the harbor into the surf zone at a nearby public beach. This fine-grained dredging experiment challenged the Environmental Protection Agency's 80/20 rule which states that dredged (non toxic) sediment released into the surf zone should contain at least 80% sand. A monitoring program was developed to determine if sedimentary changes occurred on the beaches and in benthic habitats near the harbor as a result of fine grained harbor dredging. Traditional sediment sampling techniques were combined with high resolution multibeam bathymetric surveys to produce separate before dredging and after dredging benthic habitat classifications offshore of the harbor. The two benthic habitat maps were compared in GIS using a new technique to quantify areas of sediment erosion and deposition over the monitoring period. The GIS analysis of the data lead to the conclusion that sediment released during the experimental dredging event did not significantly impact the beaches or nearshore benthic habitats in the study area. The implementation of this methodology has prompted local, state, and federal agencies to reevaluate the 80/20 rule and consider harbor sediment as a source of sand for beach replenishment.
Keywords: Monterey Bay, harbor dredging, coastal processes, benthic habitat mapping, coastal/marine GIS
From June 1987 to April 1988 an epizootic of bottlenose dolphins (Tursiops truncatus) occurred along the eastern coast of the United States from New Jersey to Florida. As a result of this mortality, the mid- Atlantic coastal migratory stocks of bottlenose dolphins was estimated to have been reduced by more than 50%, which resulted in its classification as "depleted" under the U.S. Marine Mammal Protection Act. Researchers have documented the existence of multiple coastal stocks of Atlantic bottlenose dolphins, which are believed to include a complex mix of residents, seasonal inhabitants, and transient animals. One of these putative stocks occurs approximately between Beaufort, NC and Myrtle Beach, SC; a number of the animals belonging to this stock are the focus of the present study. To investigate the community structure, we implemented and tested a variety of spatial smoothing algorithms. Most common in the literature is the adaptive kernel estimator (ADK) which has become the de facto standard in animal movement studies. Conversely, geographers and statisticians have developed point pattern and surface smoothing techniques. These two approaches were compared and preliminary results identified the geographically-based interpolation algorithms to most closely represent the dolphin distribution. Therefore, this paper explores the incorporation of distance measurements into the calculation of spatial smoothing or interpolation surfaces.
Keywords: coastal/marine GIS, dolphin, GIS, North Carolina, spatial analysis, animal movement