fact, often worse than useless.
Start with the obvious—it can't hurt. Ask the travel agent with whom you made your original booking if the company has a local correspondent Many have agents in Bali who can re-check confirmations. Even before you arrive, try to obtain something tangible from this agent and/or Merpati airlines, such as a fax or telex showing your confirmed dates. As soon as you get to Bali, re-check your bookings.
As soon as you make it to your destination, confirm your return booking. The dive resorts and many hotels are quite efficient at doing this—they will usually ask you for your plane details right away—but still make sure that it's been done.
If you do all this, it's likely-but not guaranteed—that things will work out as planned. But, just in case, keep some flexibility in your schedule in case there is a day or two of delay. If you have to sit in Bali for a day or two, there are plenty of good day-trips for diving. Unless you are traveling in a large group, go to the airport and try to get on your desired flight, even if you have been told that it's full. We've been on many of these over-booked flights where half or more of the seats are empty.
If you don't get a seat on the plane, forget about lodging an official complaint, getting mad, or punching somebody. If you throw a fit, you will provide a great deal of entertainment to the people waiting around the counter, but such unsavory behavior will inevitably lead to more delays. Sometimes—but not always—it might help to offer to pay "something extra" to get on your flight. It is not unknown that even someone with a confirmed reservation has been "bumped" due to a shady deal.
Still Worth It, Though
Are all these potential hassles worth it? You bet. Chances are you won't have problems. We just wanted to warn you—not scare you away. Remember: the diving is great out there. If you can schedule your visit from April through June, or September through early November, planes will be less crowded and everything will be much easier.
When planning your visit, don't try to visit too many places. If you have a week, go just to one place. Otherwise, you can spend much of your precious vacation time contending with the difficulties mentioned above.
REEF ECOLOGY
Coral Growth and the Formation of Reefs
Diving over a tropical coral reef has been compared to stepping into a time machine. You find yourself in a strange place, millions of years out of sync with the land. The reef is a reminder of a time when all the life on earth existed in shallow, tropical seas, the original soup of creation.
The myriad fish and invertebrates that shelter among and encrust the rugged surfaces provided by the clumps, shelves and branches of coral are overwhelming in their numbers, shapes and colors. Nowhere else is there such a diversity of animal forms.
Clear tropical seawater is nutrient poor, an aquatic desert. The strange and varied forms of the members of coral reef communities allow each to fill a niche in a complex nutrient cycle, beginning with the fixing of nutrients by the photosynthesis of algae, and working up to the barracuda that snatches an aging fish from the school. The ammonia and feces secreted by the predator are cycled right back into the reef ecosystem.
Over 240 million years, when scleractinian coral reefs first formed, this community has made a remarkable geological impact. The stony coral skeletons become overgrown and compacted into rock, eventually building up a prodigious thickness of limestone. When forced upward by the buckling of the earth's crust, this old reef rock forms islands.
Distribution of Coral Reefs
Reef-building corals require large amounts of sunlight, and thus are only found in the tropics, and even there only in shallow water. The effective limit of coral growth is usually given as 100 meters, although in Indonesia coral usually stops at 60-70 meters. Corals, even stony corals, are found as deep as 6,000 meters, but these grow slowly and do not form the diverse communities of tropical coral reefs.
The Indo-Pacific region, centered around the islands of Indonesia, harbors most of the world's coral reefs. Of the total area covered by coral reefs, 55 percent is in southeastern continental Asia, Indonesia, the Philippines, North Australia and the Pacific islands; 30 percent is in the Indian Ocean and the Red Sea; 14 percent is in the Caribbean; and 1 percent is in the North Atlantic. In variety, central Indonesia is the richest in the world: 80 genera, 450 species.
The presence of large gorgonians, crinoids and schools of planktivores like these anthias indicates plankton-rich waters, which can provide a spectacular concentration of marine life. Mike's Point, Bunaken Island, Sulawesi.
Reef-building corals grow only in water from 18° C (65°F) to 33°C (91°F). And the extremes of this range can only be tolerated for very short periods.
This explains why reefs are generally found only on the eastern coasts of large continents. The wind patterns caused by the rotation of the earth create currents that bring an upwelling of cold water (14° C [57°F]) from the depths at least part of the year to the western coasts of the Americas, Europe and Africa. Thus the Indian Ocean side of Africa has extensive reefs, and the Atlantic side almost none.
No cold currents flow through Indonesia, but even temporary rises in sea temperatures can devastate reefs. In 1983 sea temperatures around the Pulau Seribu islands off western Java rose to 33°C (91°F), killing much of the shallow reef coral there. Most has now recovered.
Turbid waters, those carrying a great deal of suspended sediment, deter reef formation. This is a very important in South and Southeast Asia, where rivers dump 70 percent of all sediments delivered to the ocean worldwide. (The Ganges is the champion, carrying almost 1.7 billion tons a year to the Bay of Bengal.) In Indonesia, the larger rivers in Kalimantan and Sumatra produce enough sediment to discourage reef formation a significant distance from their mouths, although even here some rich reefs have formed.
The Biology of Corals
True reef-building or hermatypic corals are animals grouped in the phylum Cnidaria, order Scleractinia. They all have an indispensable symbiotic relationship with dinoflagellate algae called zooxanthellae. (see "Zooxanthellae and Corals," opposite.) These algae are essential for respiration and nutrient uptake, and the vigorous deposition of calcium.
Coral skeletons are made of aragonite, a very soluble form of calcium carbonate. The material is secreted as a way of disposing of excess ionic calcium.
Grazing and predation of fish and invertebrates causes portions of the coral skeletons to die, and these are immediately encrusted with algae, sponges, soft corals, or any of a myriad forms of small invertebrates. Over time, these too are grazed, silted over by coral sand, or out-competed by other organisms, and their remains become part of another compacted layer.
The lithification of coral rock is not well understood, but a fine-grained carbonate cement seems to form in the pores of the old coral, turning it into dense coral rock. This is thought perhaps to result from bacterial action.
The buildup of limestone on the reef is not a simple process of accumulation. It is a cycle just like the nutrient cycle. Scientists studying a 7-hectare reef in the Caribbean measured an annual production of 206 tons of calcium carbonate; they also measured an annual loss of 123 tons. The greatest part of this erosion was produced by boring sponges, and the rest by grazing fishes and echinoderms.
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