Apo Island and Apo Reef

In the middle of Mindoro Strait, almost halfway between Mindoro Island and Busuanga island, lies a samll island and a very large reef system: Apo island and Apo Reef.

Apo Island is approximately 1 km in extent, low and wooded. The white sandy beaches border its east and south and its fringing reef extends up to 1 km offshore. Apo Island is separate from Apo Reef, east of it, by a deep channel about 2 kms wide. A conspicuous wreck lies stranded about 0.5 km south of the navigation light on the island.

Apo Reef is an extensive reef system in which there are two shallow lagoons, separated by a channel entered from westward. The reef extends about 9 kms to the northeast, 12 kms to the east, and 9 kms to the southeast from Menor Islet. Menor Islet is a tiny islet almost 3 kms east of Apo Island. It is only 10 m. high, wooded and marked with a beacon. The reef system is party above water.

During the summer months of March, April and May several expedition head for Apo Island and Apo Reef. It is a paradise not only for divers, but certainly also for snorkellers and those who like to be Robinson Crusoe for a while.

It is possible to camp on Apo Island. Especially for bigger groups it is not that expensive to keep the bat for a few days. It is not wise to let the boat go back, quite often the boatmen forget to pick you up again, which can be a disaster.

Types of Reefs

Coral communities are not everywhere the same, the same counts for environmental conditions. This interaction has created various types of reefs:

Atolls - in fact atolls are formations of ancient origin, often million years old. They take the shape of ring-shaped reefs enclosing a shallow lagoon and dropping away to get depth on the outsides. Usually atolls start their life as fringing reefs around volcanic islands. As time goes by the water levels rises, while at the same time the volcanoes wear off. Most atolls are found in the Pacific and Indian Ocean, there are also several in Philippine waters, such as the Tubbataha Reefs and the Cagayan Islands.

Finging Reefs - can be found in shallow waters near to land. Typically they

extend to depths of 15-45 m (50 -150 ft), depending on factors such as the profile and depth of the seabed. Good examples in the Philippines are the islands of Camiguin and Siquijor. These islands areseparated from the nearest main land by very deep-water channels, so deep that even during the last ice age they were not connected to these main lands. Another example is for instance Catanduanes, a much larger island.

Barrier Reefs - this type of reef can be found along edges of islands or continental shelves, they are substantial in size. The major difference between fringing reef and a barrier reef is that a wide and deep lagoons separates the last from the

shore. The outer edge of the barrier reef drops away deeply to the ocean floor beyond. Initially these reef were formed in shallow water, but if water level increases they built progressively upwards so that their living top parts stay close to the water surface. A nice example in Philippine waters of such a reed is the West Coast of Palawan Island.

Patch reefs, shoals - There are many places where reefs exists as isolated mounds or hillocks on the seabed. They vary in size from a few meters in diameter to thousands of meters. Some even emerge above the sea water and are topped by sand cays. They are found in usually rather shallow water and can be a serious obstruction to shipping. Many are, for instance, found in the China Sea.

Philippine Reefs

In geological terms most Asian reefs are quite young. They originated after the last ice-age, when seawater levels were 120 m. lower than today. The slowly rising level of the warm tropical waters created an excellent environment fro the forming of corals and reefs.

Tropical reefs are mainly built from corals, primitive animals closely related to sea anemones. Most of the coral types that contribute to reef

construction are colonial in nature, numerous individuals or polyps. They produce calcareous stony skeletons, ones grow on top of them and so it continues. Actually only the outermost layer of the growing reef is alive.

There are about 450 species of reef-building coral in the seas around the Philippines. Corals grow slowly, adding about 1-10 cm (0.4 - 4 inch) growth in a year. Once over a certain age they start being able to reproduce, releasing tiny forms that float freely among the plankton for a few weeks until settling to continue the growth of the reef. The forms coral create as they grow vary enormously according to the species and to the place on the reef where it grows.

Colonies range in size from arm of plates, tables or delicate leafy ronds. The growth and health of corals depends for a great deal on microscopic plants, called zooxanthellae. These are packed in millions into the living tissues of the most reef-building corals (and of various other reef animals, such as giant clams). Although reef corals also capture plantonic organisms from the water, a significant amount of their food comes directly from the zooxanthellae. It is precisely for this reason that most coral growth is in shallow clear water, the preferred environment of the zooxanthellae.

Diving in the Maldives

Just a day off and friends to hang around to. Diving in the Maldives, what a day!!!!

Let me share the video

http://youtu.be/eJcXEyxsDig

Enjoy!