Diving Sulawesi and Coral Reefs

Over 58 genera and sub genera of hard corals have been recorded in the waters that surround the Bunaken National Park, a province of North Sulawesi in Indonesia. This is almost three times that what you might find from the reefs of the Caribbean.

The ideal water temperatures for coral reefs to flourish are between 20 and 28 degrees Celsius. They also require clear waters; this is because most corals rely on an algae species known as zooxanthellae for their source of food. The algae use photosynthesis to create food, of which the excess is passed on to the coral. This is known as a symbiotic relationship, where both species benefit. In fact it is the algae that creates the colors of the reef and not the coral itself.

Corals are colonies of the same animal, individually referred to as ‘polyps’. They are joined together by a thin layer of common tissue. As they grow they secrete a calcium carbonate structure which enables them to bind together with some other type of material.

The coral reefs of Sulawesi support an incredible diversity of marine organisms including thousands of different fishes, crabs, sea stars, sea cucumbers, snails, clams and worms. Coral reefs provide a solid habitat for these organisms to survive on. The coral reefs around this area one of the best places in Indonesia to go on scuba diving holidays.

The most predominant type of reef in the Bunaken National Park is fringing reef. Fringing reefs grow along the edge of landmasses and islands. Close to the islands of northern Sulawesi are mangrove forests, from here most commonly you’ll find sea grass beds, from which the reef flat usually extends for 30 – 50 meters before reaching the reef crest and reef slope, more commonly known as the ‘drop off’. Each of these habitats will be preferential to different marine life. For example mangrove forests are ideal grounds for juveniles as they provide protection, sea grass beds provide a feeding ground for hungry turtles and the reef flat will allow corals the opportunity to flourish.

Coral reefs are in desperate need of protection, The North Sulawesi Watersports Association is an organization set up by local dive operators to ensure the protection of the area. Let us hope that diving in Indonesia keeps its high standards with the efforts of this organisation.