A guide for planners and managers - IUCN

PART I
Strategies and Tools
and evaluate areas where coral reef management efforts are needed immediately;
characterize and evaluate the status of the essential habitat of commercial and noncommercial
marine species; develop management strategies for marine protected areas;
predict and model the potential damage to populated areas caused by severe weather;
and support activities that evaluate and develop capabilities to conduct long-term
monitoring and change analyses. Since the information is maintained in a computer,
new data can easily be added. If maps of different scales are needed for specific activities
or areas, these too can easily be incorporated into the system. In addition, GIS-based
maps can be inexpensively distributed on CD-ROM or over the Internet.
5.2 Remote Sensing
Remote sensing—by satellites such as LANDSAT (USA) and SPOT (France)—can be
helpful, but the images are often very expensive. The high spatial resolution of
multiband radiometers on LANDSAT and SPOT, well proved for land survey, also works
moderately well for shallow-water survey (where waters are clear and cloud cover is
low). Remote data have their best use in coastal zone planning and management when
coupled to digital mapping and GIS technology. The US satellite, LANDSAT 7,
features an advanced Thematic Mapper and the output is said to be relatively
inexpensive.
The light you see when you look into the water is the same light used to map
coral reefs. Sunlight penetrates the water and is reflected back. The light reflected
back can tell you about the makeup of the bottom - areas that reflect brightly might
be sand; areas that reflect less brightly might be seagrass or coral reef areas. Just as
your eye sees these dark and light patterns in reflected light so does a camera. Colour
film in a camera is composed of emulsions that are sensitive to different portions -
red, green , and blue - of the visible light spectrum. Factors, such as altitude (when
an aircraft carries the camera, the water depth, and aerosols in the atmosphere affect
the amount of reflected light that hits the film. Unfortunately, no single remote
sensing technology is capable of mapping all components of a marine ecosystem. Water
depth is the primary limiting factor. As a result, complete ecosystem mapping
requires merging the capabilities of several technologies.
Remote Sensing Platforms: Light reflectance-based remote sensing technologies
can generally be grouped according to the resolution (pixel size) of the resulting data.
This resolution is affected by both the altitude of the platform from which data are
collected and the design of the instrument or camera. Low-resolution satellite
platforms such as NASA's SeaWIFS (Sea Viewing Wide Field-of-View Sensor) and
NOAA's AVHRR (Advanced Very High Resolution Radiometer) produce images where
each pixel represents an area of 1 to 10 sq. km. Moderate-resolution satellite platforms
such as LandSat, SPOT, and human-occupied spacecraft (e.g., the Space Shuttle or
International Space Station) produce images where each pixel represents an area of
10 - 30 sq. meters. Instruments mounted on fixed wing aircraft and helicopter
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