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

AUGUST 2005 FINAL REPORT
totaling approximately 70 ha (Scott 1993). There are 50.7 ha of mangrove forests on ten sites within the
Navy lands on Guam (DoN 1999b; Figure 2-10). The largest of these mangrove sites (35.9 ha) is site R
located along the eastern shoreline of the Apra Inner Harbor (DoN 1999b). This site mainly consists of
Rhizophora mucronata. Four sites near Abo Cove at the southern tip of the Inner Apra Harbor (Sites H,
O, P, and Q) amount to 12.4 ha of mangrove forests (Figure 2-10). Site H contains R. mucronata and
Avicennia alba. Sites O, P and Q contain R. mucronata. There are two mangrove sites near Dry Dock
Island (Sites V and W) and two more sites near Polaris Point (Sites S and T) (Figure 2-10). Mangrove
site S (0.6 ha) consists of Rhizophora sp., and site T (0.4 ha) of Rhizophora sp. and A. marina.
Mangroves species found at site V (1.2 ha) are A. marina, Rhizophora sp., and Bruguiera gymnorrhiza.
Site W is populated by A. marina, Xylocarpus moluccensis, and B. gymnorrhiza (DoN 1999b). Along the
southern shore of the para Harbor, there is a mangrove area at site D which consists of R. mucronata and
A. alba and covers a 0.7 ha area (DoN 1999b). Achang Bay Mangroves is centered on Achang Bay at the
southern end of Guam. This area is the only sizable area of mangrove forest in southern Guam (R.
mucronata, B. gymnorrhiza, A. marina, R. apiculata) (Wilder 1976). The forest is owned by the
government of Guam and is a 20 to 60 m wide strip lining the shore.
Mangroves in the CNMI are restricted to Saipan. These mangroves are comprised of a single species
(Bruguiera gymnorrhiza) and can only be found in a few small stands (Scott 1993) in two locations:
Puerto Rico Mudflats and American Memorial Park. Puerto Rico Mudflats (15°13’N, 145°43’E) is a series
of mudflats bounded by a national park (American Memorial Park; NPS 2004) and a landfill. Within these
mudflats is a broken fringe of mangrove trees. The largest stands of mangroves are found north of the
landfill.
2.7.8 Artificial Habitats
Artificial habitats (shipwrecks, artificial reefs, jetties, pontoons, docks, and other man-made structures)
are physical alterations to the naturally-occurring marine environment. In addition to artificial structures
intentionally or accidentally placed on the seafloor, FADs are suspended in the water column and
anchored on the seafloor to attract fish. FADs have come to be referred to as any floating object
physically placed in the water column solely intended to attract fish (Klima and Wickham 1971; Bohnsack
et al. 1991, Blue Water 2002). Artificial structures provide a substrate upon which a marine community
can develop (Fager 1971). Navigational, meteorological, and oceanographic buoys suspended in the
water column potentially function like artificial habitats. Epibenthic organisms will settle on artificial
substrates (including algae, sponges, corals, barnacles, anemones, and hydroids) to eventually provide a
biotope suitable for large motile invertebrates (e.g., starfish, lobster, crabs) and demersal and pelagic
fishes (Fager 1971; Bohnsack et al. 1991).
2.7.8.1 Artificial Reefs
An artificial reef consists of one or more submerged structures of natural or man-made origin that are
purposefully deployed on the seabed to influence the physical, biological, or socioeconomic processes
related to living marine resources (Baine 2001). Artificial reefs are defined both physically, by the design
and arrangement of materials used in construction, and functionally according to their purpose (Seaman
and Jensen 2000). A large number of items are used for the creation of artificial reefs including natural
objects, such as wood (weighted tree trunks) and shells; quarry rock; or man-made objects, like vehicles
(automobile bodies, railroad cars, and military tanks), aircraft, steel-hulled vessels (Liberty ships, landing
ship tanks, barges, and tug boats), home appliances, discarded construction materials (concrete
culverts), scrap vehicle tires, oil/gas platforms, ash byproducts (solid municipal incineration, and coal/oil
combustion), and prefabricated concrete structures (reef balls) (Artificial Reef Subcommittee 1997). The
purpose of deploying artificial reefs in the marine environment is to: (1) enhance commercial fishery
production/harvest; (2) enhance recreational activities (fishing, SCUBA diving, and tourism); (3)
restore/enhance water and habitat quality; (4) provide habitat protection and aquaculture production sites;
and (5) control fish mortality (Seaman and Jensen 2000).
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