Coral Reefs of the World Physical Features Bolinao is a small, hilly, coastal town surrounded by coconut palms and scrub. A fringing reef lies towards the south-western coast extending roughly 35 miles (6 km) down the coast to Balingasay Bay. A strait between Santiago Island and Cape Bolinao forms a perfect typhoon shelter for fair-sized vessels. The entrance is formed by a break in the coral reef which extends 1,6 km off shore north of the town and about 3 km north of Santiago Island (DND-BAGS, 1968). The area opposite the Bounao Harbour breakwater is rocky. The waters here are turbid as a result of the current systems which accumulate suspended sediments on the leeward side of Santiago Island (NRMC, 1979). Santiago Island lies north-east of Bolinao, separated by a channel. It is affected by strong winds from the north-east and south-west during monsoon seasons, but it is covered with "ipu-ipil" trees Leucaena leucocephala, shrubs and a few mangrove patches. A fringing reef surrounds most of the island, extending northwards approximately 3 km. Suaqui lies to the north, within Santiago's wide fringing reef, and is not subject to strong currents as it has a considerable distance from the reef breakers. North-west of Santiago, about 800 m from the shore, the reef slopes abruptly to deep waters where sandy substrates, dead corals and rock patches are found. The area is exposed at extreme low water springs. The western reef, opposite Barangay Ducoy, is buffeted by strong waves and strong currents especially during tidal changes. On the southern end of Santiago Island is a channel about 300 yards (274 m) wide which, at depths of up to 11 m, sweeps eastward in an L-shaped pattern to Panauan Islet (29 m). South-eastward of Panauan Island, the channel widens and becomes shallower (NRMC, 1979). Local boats of light draft take advantage of the narrow winding passage leading to Lingayen Gulf from the head of Borneo Harbour, through Narra, Siapar and Cabarruyan Islands, which are located on the south side of Santiago Island (DND-BAGS, 1968). The channel's substrate is primarily muddy-sut and sand mixture. Tagaporo Islet, located 1 km east of Santiago, is surrounded by a reef flat. Its substrate is typical of seagrass communities consisting of a mixture of mud, sand and coral rubble that extends toward the reef front (NRMC, 1979). Reef Structure and Corals Fringing reefs occur around most of the islands, the most extensive being the one north of Santiago Island. It is a windward reef with a deep east-west channel cutting through the crest on the north-east sector (NRMC, 1979). Suaqui Island has broad areas of seagrass beds (Thalassia sp) located nearshore and wide white sand flats with coral patches and bodies. The reef proper is 3-4 km away from the island and at its outer edge has a luxuriant growth of corals, with a drop-off sloping down to a depth of approximately 85 feet (26 m) (NEPC 1977; MPRPD, 1983). Of the 15 stations surveyed in Bolinao and its outlying islands, six (35) were good, eight (47) were fair and three (17) were poor in coral cover (UPMSC, 1979). The areas prolific in coral growth are located mainly north of Santiago, including Silaqui and Cangaluyan (located approximately 4 km due east of Santiago). Its 538% to 734% coral cover consists mostly of Pontes, Galaxea, Acropora, Lobophyuia, Platygyra, Montipora, Goniopora and Diploastrea. Fair coverages ranging from 263% to 44% are mostly seen in areas north-west of Silaqui, Bolinao and Points around Santiago Island. Poor coral coverages are surrounded by reef flats dominated by algae and seagrass, particularly around Balingasay and Tagaporo Island. Millepora and Heliopora are also common, and Organ Pipe Coral Slolonifera is common but not dominant. Noteworthy Fauna and Flora The fish populations are reasonable, tending to be more varied and interesting in deeper waters (MPRPD, 1983; UPMSC, 1979). The commonest fish are fusiliers, surgeon fish and parrot fish. Rabbit fish Siganus sp. are dominant in the seagrass beds and form a major fishery (UPMSC, 1979). During field surveys concerning the verification of data obtained from Landsat multi-spectral imagery, 40 species of marine algae were identified; the highest standing crops were observed from February to July (NRMC, 1979). Extensive seagrass communities are found in Silaqui, Santiago and Tagaporo Islands. Some mangrove patches are present at the north-east tip of Santiago Island. Scientific Importance and Research Bolinao and its outlying islands are the principal sites for most of the marine biological research done by the U.P. Marine Sciences Center (UPMSC). A marine research laboratory has been established here. An extensive survey of its reefs was done as part of the project involving the investigation of coral resources in the Philippines (UPMSC, 1979). A similar survey was done by NAME, although this was mainly through the use of LANDSAT imagery (NRMC, 1979). The UPMSC is carrying out studies on coral growth (eg. Acropora pulchra), coral reef recovery and recolonization and coral transplantation. Various aspects of these studies are reported in UPMSC (1980 and 1982), Yap (1981 and 1983) and Yap and Gomez (1981 and 1984). Artificial reefs using scrap rubber tyres were set-up in November 1978 off Lucero, Santiago Island, to determine feasibility and productivity (Murdy, 1979). Studies on trophic dynamics of coral reefs are being carried out at Silaqui and Cangaluyan Islands. Additional studies include the growth and reproductive biology of Giant Clams Tridacna spp, Strombus, scallops Amusium sp. and rabbitfish Siganus sp. Past research includes an invertebrate and floristic survey of Bolinao and its surrounding islands (Lopez, in press; Saraya, 1979 and 1982). Economic Value and Social Benefits Fishing is the primary source of income around Bolinao. Nets and fish traps are the main methods but dynamite fishing is common in the extensive reef areas of Santiago and other islands. Bolinao is one of the main collecting sites for the aquarium fish trade (Albaladejo and Corpuz, 1981). There is an important shellcraft industry on Santiago Island (Wells, 1982b). A considerable number of tourists frequent Bolinao for its diving sites and white sand beaches and the harbour is used by fair sized vessels (DND-BAGS, 1968). Disturbance or Deficiencies Dynamite fishing, fish collection using cyanide, station, and some predation by Acanthaster planci contribute to reef deterioration. Detrimental effects have been observed on invertebrates exposed to ichthyocides (Cowan, 1980). -242