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

AUGUST 2005 FINAL REPORT
on the inner reef flat was composed of Porites, Pocillopora, and Leptastrea and on the outer reef flat,
coral cover was composed of Porites and Goniastrea corals (Randall et al. 1982). As mentioned earlier,
many environmental changes have occurred in Guam since the 1908-1981 Randall et al. survey. An
update is needed on the status of the coral populations of the Luminao Barrier Reef on the seaward side
of Glass Breakwater, the fringing reef on the seaward side of Cabras Island, and the fringing reef east of
Cabras Island.
Haputo ERA—The Haputo ERA is located along the northwestern karstic coast of Guam, between
Haputo Beach and an area located approximately 840 m north of Double Reef (Pugua Patch Reef)
(Figures 1-1, 2-7a, 2-7b, and 2-7c). The marine portion of the Haputo ERA covers a 29 ha area (DoN
1986). The following information on the Haputo ERA marine community is taken from Amesbury et al.
(2001).
The Haputo ERA coastline is characterized by exposed and narrow supratidal exposed benches (less
than 5 m wide, raised 0.5 to 1.5 m above sea level) alternating with vertical cliffs. There are six main
macrohabitats supporting corals in the Haputo ERA within the 1 to 18 m water depth range: exposed
benches, protected reef flats, Double Reef Top, the back reef, the shallow fore reef, and the deep fore
reef. Macrohabitats on the fore reef (1 to 18 m in depth) support more diverse assemblages of corals,
macroinvertebrates, and fish than the three shallow macrohabitats. Corals, however, have the greatest
diversity in shallow water on Double Reef. Coral cover ranged from 37 to 64% in the Haputo ERA. Coral
cover is higher along transects taken at an 8 m depth compared to those taken at 15 m, and coral species
with the highest coverage in the Haputo ERA include Porites (deep area), Montipora (shallow area), and
Leptastrea.
Amesbury et al. (2001) found 21% of the known marine fauna of Guam within the Haputo ERA. These
organisms consisted of 154 species of corals, 583 species of other macroinvertebrates (>1 cm), and 204
species of fish. The 154 coral species found in the Haputo ERA correspond to approximately 60% of the
coral species known on Guam, and the 204 fish species, 22% of the fish known on Guam. The marine
portion of the Haputo ERA is therefore an area of relatively high biodiversity, yet because of overfishing,
the fish in the Haputo ERA are not very diverse or abundant.
Shallow splash pools found on the exposed benches support low diversities of corals, fishes, and cryptic
organisms. Shoreward of the benches and at the base of the cliffs are erosional notches created by wave
action on the rock face where habitat-specific species of limpets, chitons, slugs, and shore crabs can be
found. The seaward edge of the benches is a steep subtidal face typically burrowed by echinoids that
supports corals, macroinvertebrates and fishes.
Protected reef flats (fringing reefs) off Haputo Beach and shoreward of Double Reef are intertidal habitats
supporting few species of corals (including Pavona divaricata), hermit crabs, crabs, sea slugs, and sea
cucumbers that can withstand the rigors of an exposed habitat. Corals and fishes are more common and
diverse at the seaward margin of these reef flats.
The Double Reef Top is a reef front environment that supports healthy corals and high coral cover (>75%)
consisting of Acropora valida, A. digitifera, and Pocillopora species. The exposed reef pavement has
been honeycombed by echinoids.
The shallow fore reef substrate within the Haputo ERA includes a steep reef front and gently sloping fore
reef starting at a 4 to 8 m water depth. Numerous cuts and channels normal to the shoreline run through
the fore reef and create abundant structural complexity. The highest coral cover (54 coral species) within
the Haputo ERA is found between these cuts and channels. Amesbury et al. (2001) recorded three new
sponges for Guam in this macrohabitat (Neofibularia hartmani, “yellow tough sponge,” and “puff sponge”).
Branching corals (Acropora, Pocillopora) dominate the 1 to 3 m depth range on the fore reef. Coral
composition within the 4 to 9 m depth range varies within the Haputo ERA, including several areas
dominated by encrusting species of Montipora while other areas are dominated by the massive Porites.
The reef front off Haputo Beach contains very large corals of diverse faviid species (>0.5 m diameter)
which makes it distinctive compared to other locations of Guam. Elsewhere on Guam abundant large
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