Status of Coral Reefs of the World 2000

Status of Coral Reefs of American Samoa and Micronesia
Guam
Sedimentation is the major anthropogenic problem for the central and southern reefs of
Guam. For the Ugum River Watershed on Guam, the rate of soil erosion was estimated at 290
tons per ha per year; 46% from sloped roads, 34% from ‘badlands’ – land burnt regularly for
hunting. Ugum Watershed erosion rates doubled from 1975 (6,189 T/Y) to 1993 (12,159 T/Y),
mainly from road construction and development, and this is accumulating on reefs and
reducing coral diversity and abundance. Coastal pollution, eutrophication and sewage have
increased on Guam during a development boom in the late 80s and early 90s, as have
increased stormwater runoff from the airport expansion, new roads, hotels, shopping
centres and golf courses. The salinity of coastal waters can drop below 28 o /oo during
summer coral spawning events, which results in reproductive failure. Sewage treatment
plants divert the wastewater directly into the ocean outfall pipes without treatment during
storms, which discharge within 200m of the shore at depths of 20-25m where the corals
grow. Extensions of the Northern and Central District outfalls into deeper waters further
offshore are planned. A variety of pollutants occur in sediments of Apra Harbour, including
PCBs, heavy metals and PAHs. Over-fishing and habitat destruction are continuing problems.
Fish populations and catch per unit effort (CPUE) have declined since 1985 through the use
of unattended gill nets, bleach, scuba spearfishing and fish traps along with habitat loss due
to sedimentation, pollution and physical damage. More than 1 million tourists visit Guam
each year, and most have little coral reef conservation ethic or awareness. This leads to
damage to reefs by scuba divers and snorkelers, during underwater walking tours using
surface-supplied equipment and many watercraft (jet skis). Fishing vessels, recreational
watercraft and ships carrying cargo and illegal immigrants often run aground and cause
localised damage to reefs, and the Navy has been responsible for reef damage within Apra
Harbor. The main power generation facilities on Cabras Island, Apra Harbor dump high
temperature seawater and cleaning chemicals, which both result in coral mortality.
Palau
While much has been achieved in guiding tourism to have limited impacts on reef
resources, the volume of divers with poor training is increasing, causing damage to some
reef sites. The use of mooring buoys, laws preventing coral collecting, and diving tour
operator education are all helping to conserve the reefs. The greatest threat is the Compact
road project for Babeldaob because of the great potential for erosion and sedimentation,
and for opening up of large areas to development, and increased reef use. Dredging is
planned for fill materials for the road base, which is more potential for reef damage.
Increased population, both local and visitors, will require better sewage treatment.
Foreign-based fishing activities are a problem for Palau, with poachers from Indonesia and
the Philippines damaging Helen Reef, and moored fishing vessels causing eutrophication in
Malakal Harbour.
CURRENT AND POTENTIAL CLIMATE CHANGE IMPACTS
American Samoa
A steady rise in air temperature over the past 20 years suggests future climatic uncertainty
and a probable increase in the frequency of hurricanes in the region. The record high
temperatures in 1998 El Niño/La Niña caused droughts on land and unusually low tides that
caused mortalities among exposed corals. Many reefs experienced extensive bleaching
during elevated seawater temperatures in 1994.
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