M Applets M Applets

let pp s aMapping the Seafloor comprehensive documentation of tiny beams at a maximum ping rate of M their plants, animals, and submarine 25 Hz and an angle of 130 degrees M American Samoa topography existed. Indeed, virtually (1.5 ϫ 1.5 degree beams are spaced In the southwestern Pacific Ocean lies nothing is known about the world’s 0.9 degree apart). This yields swaths American Samoa, a small archipelago shelf-edge (50–120 meters deep) coral as much as four times greater than the of five islands and two coral atolls that reef habitats and no global inventory water depth. At normal survey speeds represent the only U.S. territory south of shelf-edge, benthic species exists. of 3–12 knots, the sonar can capture of the equator. American Samoa is In 1998, though, the Sustainable data at depths as great as 100 meters, home to Fagatele (Fohng-ah-teh-leh) Seas Expeditions (SSE, http:// with data gridded at spacings of Bay National Marine Sanctuary sustainableseas.noaa.gov) launched a 0.25–25 meters. Positions are (FBNMS), the smallest, most remote, major initiative to remedy this situa- recorded using GPS. With no differen- and least explored of the 13 sites that tion. SSE has pioneered the use of new tial corrections available at the time, make up the U.S. National Marine technologies, including the single- we achieved a sounding accuracy of Sanctuary System and the only true occupant submersible DeepWorker, about 24 meters (points fell within a tropical coral reef among those sites. to explore, document, and provide circle of radius 24 meters) and data Yet another treasure in the islands is critical scientific data for marine were gridded at a 1-meter resolution. the National Park of American Samoa, sanctuaries, with the goal of develop- In only two weeks, we obtained full one of the few sites within the Depart- ing a strategy for restoring and con- bathymetric coverage around selected ment of Interior’s National Park Ser- serving these resources. SSE’s mission sites off the main island of Tutuila, vice (NPS) that includes both land and plan includes three phases: photo-doc- including FBNMS, part of the ocean. umenting sanctuary plants, animals, National Park (NP), Pago Pago Until recently, both the sanctuary and habitats at depths as great as 600 Harbor (PPH), Taema Bank (TB), and and the park were largely unexplored meters; expanding the characteriza- Faga'itua Bay (FB, see Figure 1). After below depths of 30 meters, and no tion of habitats, focusing on those of the surveys, we cleaned the navigation larger animals such as whales, data to eliminate erroneous positions sharks, rays, and turtles; and and applied National Oceanic and finally, analyzing and interpret- Atmospheric Administration tidal cor- ing these data and conducting rections to the depth soundings. We extensive public outreach and then gridded ASCII-formatted x,y, education. and z depth data using a public- As part of phase one, I col- domain suite of software tools for laborated last spring with processing and display of swath sonar FBNMS Manager Nancy data. Initial maps made from the grids Daschbach, and University of revealed many important features, South Florida (USF) scientists such as reef terraces, erosional rem- FIGURE 1 This map of American Samoa indicates areas surveyed David Naar and Brian Don- nants, volcanic edifices, and blocks of (pink circles) in spring 2001. The inset photo is the marine sanctuary. ahue, to complete bathymetric reef debris (see Figure 2). Mapping of surveys in both the Pago Pago harbor also captured in marine sanctuary striking detail the wreckage of the and the national USS Chehalis, a World War II–era oil park. I then began and gas tanker that exploded and to integrate this and sank in the harbor in 1949, and may other baseline data still be a source of water pollution (see into a GIS. Figure 3). To map the area’s We then converted bathymetric underwater topo- grids to Arc format. These grids con- graphy, we used a stituted the base layers for the new portable multibeam FBNMS GIS. The GIS also comprised bathymetric map- an initial compilation of terrestrial ping system, data layers — including a 10-meter attached to the bow digital elevation model of Tutuila — of a 30-foot survey various digital line graph and digital boat. The sonar sys- raster graphics files, shapefiles, cover- tem operates at an ages, and grids, all obtained from acoustic frequency NPS, the U.S. Geological Survey, the FIGURE 2 This histogram-equalized, shaded-relief bathymetric map reveals the of 300 kHz, fanning Digital Chart of the World, and other Taema Bank, a drowned coral reef terrace 3 kilometers off the coast of Tutuila. out as many as 127 sources. 24 Geospatial Solutions May 2002 www.geospatial-online.com To make all data sets in the FBNMS Mapplets GIS accessible — not only to the sanctuary staff and their collaborators in Ameri- can Samoa but also to parties throughout Oceania and the United States — we built a Web clearinghouse (see http://dusk.geo. orst.edu/djl/ samoa). The clearinghouse provides links to all of the GIS data and metadata, bathymetric grids in Generic Mapping Tools format for non-GIS users, maps, photographic images, and graphics. All GIS data are provided as export interchange files, which may be imported into GIS software. Ground truthing. Ground truthing our bathymetric surveys with photography and videography is an ongoing endeavor. For example, the new bathymetry of the FBNMS helped to guide the location of a FIGURE 3 This color-shaded, sun-illuminated bathymetric map shows the wreck of the USS deep-diving mission to the sanctuary on Chehalis in Pago Pago Harbor. The inset ship is the same class as the Chehalis. Cartography by Brian Donahue, inset photo courtesy of nara.gov/publications/sl/navyships/auxil.html. May 16, 2001 (see Figure 4). University of Hawaii researcher Richard Pyle used rebreather technology to work underwa- conducted aboard the R/V Rev- ter for more than 3.5 hours (significantly elle in March 2002. These data longer than possible with traditional will enable us to characterize the SCUBA), and collected videotape of coral volcanic flanks of Tutuila at reef biota and habitats as deep as 113 depths greater than 100 meters. meters. Although the mission was cut In December, we plan to con- short by poor weather, Pyle observed 12 duct additional shallow-water completely new species of fish in the bay, surveys. In addition to bathyme- 17 species that had never before been try, these surveys will include the observed in American Samoa, and several gathering of backscatter imagery species that were previously unknown to (representing the strength of the the waters of Fagatele Bay. return signal rather than just the And in March 2002, SSE founder Dr. travel time), so that seafloor Sylvia Earle, a famed marine biologist classification and habitat maps and National Geographic Explorer-in- may be prepared and integrated Residence, led a small diving, photo- with high-resolution satellite graphy, fish count, and public outreach imagery. These maps will be the mission in the area. Earle, along with basis for ongoing studies in the Kip Evans, Gale Mead, former National sanctuary and the park that will Marine Sanctuary Program Director include selecting sites for habitat Francesca Cava (all from SSE), Brian class designation and protection Donahue from USF, Laddie Akins of the (no-take zones), developing Reef Environmental Education Founda- sanctuary program monitoring FIGURE 4 The solid line delineates the estimated dive track of a rebreather diving mission in the FBNMS tion, and Nancy Daschbach, made 60 protocols, and obtaining a gen- immediately following our bathymetric survey. dives at the sanctuary and several other eral understanding of species sites around Tutuila. They created an composition and abundance. extensive collection of underwater video The survey team logged and visualized soest.hawaii.edu) and converted to GIS and still images, and observed and docu- bathymetric data with Kongsberg- format with ArcGMT (http://dusk. mented 30–50 species of corals, four dif- Simrad’s Merlin software (www. geo.orst.edu/ arcgmt). The FBNMS GIS ferent shark species, more than 200 fish kongsberg-simrad.com), postprocessed was built using ESRI’s (www.esri.com) species, and 20 invertebrate species. with Kongsberg-Simrad’s Neptune ArcView 3.2 and ArcInfo 8.1. Future stages in the unveiling of the software, and gridded with MB System seafloor will include the postprocessing (www.ldeo.columbia.edu/MB-System/ Dawn J. Wright, Department of and gridding of bathymetric data gathered html/mbsystem_home.html). Initial maps Geosciences, Oregon State University on a 1-day circuit of the island, which we were produced with GMT (http://gmt. www.geospatial-online.com Geospatial Solutions May 2002 25.

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