Marine Resources Assessment for the Marianas Operating ... - SPREP

AUGUST 2005 FINAL REPORT
ESRI's proprietary macro-language, to automate the more repetitive map-making tasks as well as the
processing and analysis of large volumes of data.
1.4.2.1 Maps of the Physical Environment⎯Oceanography and Habitats
Bathymetric data from Sandwell et al. (2004) were sampled at 2 minute (min) resolution and were
acquired as geographic coordinates giving depth below mean sea level. Depth data were imported into
the Spatial Analyst module of ArcView ® , which interpolated and contoured the data at 50 m intervals for
waters shallower than 100 m and at 500 m intervals for waters deeper than 500 m. Selected isobaths
from the resulting two-dimensional contours are shown on the bathymetry figures and on various maps
throughout the MRA report.
To illustrate the three-dimensional (3D) bathymetry of the Marianas MRA study area, triangular irregular
networks (TINs), which interpolate intermediate data values between surveyed data points, were created
using the available bathymetry data and processing those data in the ArcGIS ® 3D Analyst extension. The
2 min bathymetric sounding data sampled from Sandwell et al. (2004) were used to create the TIN, which
depicts the 3D bathymetry of the study area (Figures 2-1 and 2-4). The TINs were viewed in the ArcGIS ®
8.3 ArcScene extension to model the 3D display. ArcScene ® allows the 3D display to be manipulated
(i.e., rotated, tilted, zoomed, classified, and overlaid with data). The most authentic display was exported
directly from an ArcScene ® view as a graphic file (.tif), which was then imported into ArcView ® for the final
map layout.
Seasonal averages of sea surface temperature (SST) were obtained from the NASA and compiled from
weekly averaged Advanced Very High-resolution Radiometer (AVHRR) images, which contain multichannel
sea surface temperature (MCSST) pixel data for the years 1981 to 2001. Seasonal averages of
chlorophyll a (chl a) concentrations were also obtained from the NASA and compiled from monthly
averaged Coastal Zone Color Scanner (CZCS) images taken from 1978 to 1986 to provide a proxy of
primary productivity for the study area. Seasons were defined with the same monthly derivations used
throughout the MRA report (dry=December through June, rainy=July through November).
Multiple sources of data and information were used in the creation of maps for the oceanic and coastal
habitats located in the Marianas MRA study area and vicinity. The maps displaying benthic communities,
chemosynthetic communities, and artificial habitats (Figures 2-3, 2-13, and 2-14) are good examples of
multiple data sources used in the creation of a single map. These maps were created using scanned
images, coordinate data, GIS shapefiles, and other information available in the scientific literature and
technical reports.
1.4.2.2 Biological Resource Maps⎯Species of Concern
Marine mammal and sea turtle occurrence data were accumulated from every available source; however,
it was impossible to obtain every data source in existence for the Marianas MRA study area. An overview
of all existing marine mammal and sea turtle data sources is found in Appendix A-3. Available marine
mammal and sea turtle data displayed on the maps included in this MRA are listed in Table A-1. The data
described in Table A-1 include occurrence data from marine surveys, opportunistic sighting programs,
and stranding records. Miscellaneous sighting and stranding data available from the scientific literature
were also used in this MRA. These literature-based records represented the vast majority of occurrence
data that were available for marine mammals. Not included in Table A-1 are occurrence data from
incidental fisheries bycatch records, release and recapture programs, and nesting surveys, as these
types of data either were not available for inclusion at this time or did not possess the necessary detail
required for inclusion in the GIS. The combined source data mentioned above were vital to the creation of
occurrence polygons for protected species potentially occurring in the Marianas MRA study area.
When working with the marine mammal and sea turtle data, several assumptions were made. First, it was
assumed that the species identifications given were correct. This assumption was necessary since the
reliability of species identifications from one dataset to the next was not always known. For the sake of
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