Komodo National Park
Photo by Burt Jones
Because of its remote location and lack of facilities for divers, marine scientists are just beginning to explore the water-filled laboratories that hover beneath Komodo's waves. In 1996 I collaborated with a team of Indonesian and foreign experts on the initial underwater survey of Komodo. The expedition visited fifty of the park's dive sites over a period of ten days. We dived intensively, each of us drifting in Komodo's swift currents and recording the species we observed on plastic underwater slates. Every dive brought more astonishing results and confirmed that Komodo's wealth of fishes, corals, and other marine invertebrates was unprecedented.
Considering its limited time span, the results of the fish survey were particularly impressive. Nearly eight hundred species were registered, including a damselfish (Pomacentrus) and cardinalfish (Apogon) previously unknown to science. Maumere Bay, on nearby Flores Island just east of the park, holds the unofficial record of 1334 fish species recorded in a geographically restricted area, but these animals were counted during several visits over a five year period. Certainly almost all of the Flores species could be expected at Komodo which would boost the park's total species to well over one thousand.
An abundance of corals rivaling any location in the huge Indo-Pacific faunal province thrives in Komodo National Park. Preliminary surveys indicate a total of about three hundred and fifty species, but species are being added as the survey area expands. Both coral and fish are most abundant in the warm-water sections characteristic of northern Komodo and scattered islets immediately offshore. Sessile, flamboyantly-colored invertebrate life, particularly echinoderms, sponges, and tunicates, dominate southern Komodo's cooler waters.
Why does Indonesia in general and Komodo in particular support such an extraordinary variety of marine life? The complex answer is based on a unique combination of past and present biological and physical factors. Today this insular region forms an archipelago that spans more than five thousand kilometers across forty-six degrees of longitude. Species diverge whenever they are isolated from their ancestral populations. Indonesia's vast distances and sheer number of islands have aided greatly the fragmentation process. Every time that a small chunk of land broke away from a larger land mass and formed its own island, or the earth spewed out a bit of new land from its molten core, Indonesia's species, even the ocean-dwelling ones, slowly evolved into separate biological identities from their original populations.
Sea level fluctuations in past geological ages have caused radical changes in island topography. Huge drops during the Pleistocene epoch linked the southeast Asian mainland with Sumatra, Java, Kalimantan, and some of the Lesser Sunda Islands This land bridge formed a significant barrier to dispersal and further fragmentation of marine populations. Indonesia also straddles the Pacific's notorious "ring of fire", a volcano-plagued boundary between oceanic and continental plates. Volcanism has no doubt caused local extinctions in some areas, but it also creates new foundations where marine life can flourish eventually. Furthermore, the variety of marine habitats found throughout the archipelago create myriad opportunities for evolution.
Few dive destinations can match Komodo for sheer adventure, adrenaline-charged excitement and the thrill of discovery. But ask any diver for his or her impressions of Komodo and it's almost guaranteed that they will shake their heads and complain about the fierce currents. Kal Muller, author of Underwater Indonesia, introduced me to this phenomenon on my very first dive at Komodo in 1994. Ever the intrepid explorer, Kal insisted we check out an isolated reef off the north coast, renowned as a hot spot for big trevallies, sharks, and manta rays. Minor surface swirls had developed into spinning whirlpools, and the current was running out of control by the time we hooked anchor. In hindsight I should have aborted the dive, but went against my better judgment and jumped in. Big mistake! Immediately the curling rip began to hurl me along at a frightening rate, pulling me right off the rocky pinnacle and into the blue. There was no use fighting it. I tried to remain as calm as possible under the circumstances, and quickly swam down towards the safety of the bottom where I could grab something solid. Welcome to Komodo diving!
The following week we explored southern Komodo's steep rocky shoreline. Moments after leaping off the boat I plunged exhilaratingly down a spectacular undersea wall. Multitudes of sponges shared the substrate with giant sea fans and hordes of pastel-colored crinoids, turning the wall into a rich kaleidoscope of life. Suddenly I realized I was sinking much too quickly. Then I noticed my scuba bubbles going straight down. I swooped beneath the protection of a large black coral tree and hung precariously on the wall catching my breath, then inched over to a nearby ledge and watched a parade of swirling trevally tumble past. Anyone diving in Komodo should be prepared to expect the unexpected.
Water temperatures in Komodo National Park fluctuate wildly. The sea surrounding the northern side of the islands is invariably warm, as it should be within 10 degrees latitude of the equator. But only thirty kilometers away around the southern perimeter of the park, upwellings of cold water from the abyss make frequent and unscheduled appearances. My most vivid recollection of Komodo's unusual temperature ranges involves a dive I made during the 1996 survey while wearing my usual three millimeter tropical suit. The dive plan called for a quick descent to forty meters and then a leisurely swim back up the slope to record all the encountered fish on our plastic writing slates. The water felt unusually chilly at the beginning of the dive, but not uncomfortable. My thermometer read twenty-one degrees centigrade. The deeper I went the cooler I felt until I began shivering at a depth of thirty-five meters. I suddenly encountered a clearly visible thermocline--a pronounced blurring that marks the collision of two water masses with radically different temperatures. I tentatively extended my hand into the blurry water, abruptly withdrawing it. I couldn't believe how frigid that water was; an unbelievable fourteen degrees centigrade, or about as cold as the Southern Ocean around southwestern Australia during middle of winter.
Ironically these same inhospitable forces, strong currents and cold water, constant concerns for divers, are the very elements that attract some animals and are at least partly responsible for Komodo's extraordinary abundance of marine life. The low water temperatures in particular have very interesting biological implications because Komodo's cool waters draw in organisms usually restricted to temperate seas well outside the park's tropical boundaries.
One of the most obvious examples is a large species of surgeonfish belonging to the genus Prionurus. I first encountered this animal while I was snorkeling on Komodo's western shore, and I could scarcely believe my eyes. Only a handful of Prionurus species are known, recorded from far-flung cool-water areas including Japan, south-eastern Australia, and the Galapagos. My initial impression on seeing this animal so near the equator was akin to the disbelief registered by the actors posing as scientists observing dinosuars in Hollywood's Jurassic Park.
The Prionurus, which is new to science and still lacks a Latin species name, survives in tropical Komodo because of the frigid upwellings carried in by Komodo's ferocious currents. The seas surrounding other islands in the Lesser Sunda Group, as well as the much larger islands of Java and Sumatra also host strong currents that bring in colder-than-normal water. Oceanographic studies have revealed a consistent sea level difference between the northern (Pacific) and southern (Indian Ocean) shores of the islands. Even though the difference is small (twenty to forty centimeters), it is just enough to generate a gross downhill flow into the Indian Ocean Basin, especially when tides and winds are favorable. The archipelago's southern tier of islands acts like a dam and holds back the warmer Pacific waters which are forcibly discharged through numerous narrow straits or "spillways" into the Indian Ocean.
The net result is horrendous currents that literally rip through the restricted land gaps. Even casual observers with little or no interest in the mechanics of oceanography are awe-struck when they first see this phenomenon. The channel between Sumbawa and Komodo which has been compared to a massive twenty-kilometer-wide washing machine, is typical. Currents are totally unpredictable and run at speeds of five to six knots in every direction. Tongues of opposing currents collide frequently, forming spectacular surface whirlpools.
These unrelenting currents are partly responsible for Komodo's amazing variety of sessile encrusting organisms. The strong surface currents which run predominantly from north to south form a "wake" effect on the southern or lee side of the islands. Surface waters are forcibly pushed out into the Indian Ocean and create a pressure void along the rocky southern shores. Cold water rises up from the abyss and rushes in to replace water removed by surface currents. A by-product of the upwelling phenomenon is greatly increased production of phytoplankton, a nutritional boon for southern Komodo's bottom-dwelling filter-feeders.
Phytoplankton production has far-reaching biological effects. These microscopic single-celled plants constitute a vital first step in the food chain. Upwellings transport dissolved nutrients, the product of bacterial decomposition of organic detritus, to the surface. These nutrients act like fertilizer and cause rich blooms of phytoplankton. Most of the organic material that sustains life in the sea is synthesized by the endless varieties of phytoplankton within the shallow, well-lighted surface layers of the ocean. They provide food for herbivorous zooplankton and some small fishes, which in turn support a succession of actively swimming predators. In the rocky shallows additional food also is available from the growth of larger fixed plants and from land drainage.
The increased productivity evident at Komodo is responsible for unusual population explosions of several organisms, some which are seldom seen elsewhere. One of the most spectacular dive sites is situated midway along the western coast at Pulau Tukohlehokgebah. This rocky islet literally teems with small mid-water swimming fishes, including thousands of Scalefin Anthias (Pseudanthias squamipinnis). Peculiar bright blue phallic-like sea squirt colonies (Neptheis fascicularis) cluster on the rocky bottom. Blazing combinations of gaudy colors, predominantly red, blue, and yellow, crowned with golden feeding tentacles adorn the "Sea Apple" holothurian (Pseudocolchirus violaceus), another seldom-seen marine oddity which is common at several sites along the park's southern shores. These animals are so abundant at one location along the west side of Gilimota Island the site has been dubbed the "Apple Orchard".
As a diving scientist and underwater photographer, the thing I enjoy most about diving in Komodo National Park is its unpredictable nature, no doubt the product of its confused currents. These raging currents which randomly disperse pelagic larvae, the fragile ocean-going first stage in the life history of most reef organisms, have a pronounced mixing effect. Think of the Komodo area as a gigantic rotary beater thoroughly blending its larval brew. The successful recruitment of a given species at a particular location depends not only on a sufficient supply of larvae, but especially on the whims of the unpredictable current patterns, which virtually transform the colonization of reef organisms at a particular site into a lottery. No doubt this phenomenon accounts for the numerous one-time sightings of many animals. For example, during the 1996 survey the Green Chromis damselfish (Chromis cinerascens) was seen at only a single place, in spite of suitable habitat at many other locations.
Fishes are the most conspicuous animals on Komodo's reefs. The rich and varied fauna consists mainly of species associated with coral and rocky reefs. The most abundant families in terms of number of species are damselfishes (Pomacentridae), wrasses (Labridae), gobies (Gobiidae), cardinalfishes (Apogonidae), groupers (Serranidae), butterflyfishes (Chaetodontidae), surgeonfishes (Acanthuridae), blennies (Bleniidae), snappers (Lutjanidae), and parrotfishes (Scaridae). These ten families collectively account for 63 percent of Komodo's total fishes. I recently devised a technique for assessing and comparing fish diversity for sites across the vast Indo-Pacific. The method essentially consists of comparing species totals for key indicator groups: butterflyfishes, angelfishes, damselfishes, wrasses, parrotfishes, and surgeonfishes. Komodo's total for these groups, 284 species, is surpassed only by Maumere Bay, Flores on a lengthy list of the world's richest localities. Although the comparisons are based on fishes, a similar wealth of other marine organisms surely can be expected.
In spite of Komodo's extraordinary marine life I doubt that any species is solely confined to the area. Komodo and the surrounding Indonesian Archipelago are part of the vast Indo-west Pacific biological province, stretching eastward from East Africa and the Red Sea to the islands of Micronesia and Polynesia. The ocean-going larval stages of most reef organisms are responsible for this faunal continuity. Depending on the species, the fragile larvae, are transported in surface currents for periods ranging from a few days to many weeks. Although most families as well as many genera and species are consistently present across the region, the species composition varies greatly according to locality. Komodo's marine fauna is comprised of a very special and unique blend of animals, and the park's marine resources deserve protection as much as the its more publicized terrestrial wildlife.
The widespread use of cyanide and explosives for catching aquarium and food fishes has reached plague proportions throughout Southeast Asia. Unfortunately Komodo has not escaped these illegal practices. Deadly home-made bombs are concocted easily with readily available ingredients such as fertilizer and diesel oil. They not only kill huge numbers of fish, but cause serious long-term degradation of the coral reef environment. Reefs that formerly supported lush coral gardens are routinely reduced to rubble. Local fishermen invariably claim that the illegal poachers originate from surrounding islands rather than sparsely populated Komodo. Although the government desires to halt poaching and dynamite fishing it is terribly difficult to implement effective controls due to the park's large size and the lack of trained and well-supplied ranger-manned patrol boats. A recent positive first step was the seaward expansion of the boundaries of Komodo National Park. Although the marine environment is now officially protected, there still is a genuine need for police or military support as poachers are frequently armed.
Along with more effective law enforcement, it is hoped that the government will implement a comprehensive conservation-oriented education program specifically aimed at Indonesian youth. The fate of Komodo (and other Indonesian reefs) is really in the hands of the people, and their education process must foster awareness of the very special character of Komodo's marine life and the need to nurture it for future generations. This is a real challenge which should concern all conservationists, not just the few people who are fortunate enough to dive beneath the dragon's realm.
Copyright by Dr. Gerald. R. Allen. Used with permission.
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