This is the HEART OF THE CORAL TRIANGLE; the bull’s eye of marine biodiversity.
We are blessed to have oceans brimming with distinct and productive ecosystems. From the frigid Arctic Ocean filled with the largest aggregation of Atlantic cod left on the planet, to the warm tropical seas of the Indo-Pacific boasting the highest number of coral and fish species on Earth, our world’s waters are endlessly varied and diverse.
Endemic species make each ecosystem unique and every habitat has its own inherent value, but certain locations are of particular importance whether because of economic, cultural or biological significance.
Raja Ampat, which translates to Four Kings, is a 1,500-island archipelago located at the intersection of the Indian and Pacific Oceans. It is the central of the Coral Triangle, a region known for its unprecedented marine biodiversity that is composed of six countries: the Philippines, Solomon Islands, Indonesia, Malaysia, Timor Leste, and Papua New Guinea. The Raja Ampat archipelago makes up the north-western corner of Indonesia’s West Papua province and is part of the Bird’s Head Seascape. Raja Ampat, is the heart of the coral triangle; it is fondly referred to as the bull’s eye of marine biodiversity, and for good reason.
Often called the “species factory”, the number of species that call this place home is staggering, especially in comparison to what is considered normal for other parts of the world. There are 1,400 species of reef fish here as well as 600 species of hard corals, making up 75% of the world’s total species population. Even the healthiest Caribbean reef ecosystems only host between 500 to 700 fish species and about 65 varieties of hard coral. Raja Ampat also contains five of the world’s seven sea turtle species, 700 types of molluscs, and 13 marine mammal species. The wide range of species and rainbow of colours make Raja Ampat a spectacularly beautiful place to explore underwater.
But this awe-inspiring variety serves a much greater purpose than just aesthetics. According to Dr. Gerry Allen, “One of the drivers of this extraordinary biodiversity is the high diversity of habitats, ranging from shallow reef habitats which include fringing, barrier, patch and atoll reefs to deep channels between the main islands.”
Biodiversity is an extremely strong indicator of ecosystem resilience. Studies show that reef communities with high biodiversity are able to maintain a consistent fish biomass even in the face of rising sea temperatures. High-diversity communities also only suffer about half as much as those with low-diversity during drastic temperature fluctuations. The explanation seems to be that when temperature fluctuates, a community with “numerous species has better odds that at least a few species can thrive in the new normal.” In addition to species richness, functional diversity, or how fish utilize their environment, is closely linked to fish biomass and the ability of a given marine ecosystem to tolerate warmer waters. This buffering effect of diversity is likely one of the reasons that the reefs of Raja Ampat have remained relatively isolated and protected from climate change.
And it is not just the variety that is astounding, but the sheer biomass associated with this region, too. Schooling fish species such as silversides, scad, and jacks occur in mind-boggling quantities, sometimes almost completely covering the reef or enveloping divers with their massive numbers. Storms of fish paint the backgrounds of photos to look like vast clouds of silver slivers whirling through the blue. This mass of scaled life is dense enough to block out the sun, creating a living eclipse of fish. Like murmurations of starlings, each creature never touches the others or anything around them and they move together with the accuracy of a single organism. Being in the middle of a school of fish exhibiting shoaling behaviour is an unforgettable and completely surreal experience. Observing a diver in the midst of this organized frenzy is equally if not more ethereal. This is one of those occasions where the silence of the sea greatly enhances the view. With no noise to distract the brain, your other senses can better focus on the otherworldly nature of becoming part of this complex pattern of movement.
These massive aggregations of schooling fishes are one of the signature features that make Raja Ampat such a famous destination for underwater explorers. Having personally dived in the Philippines, Malaysia, Vietnam, Thailand, and Bali, I will say on an anecdotal note that I have never seen such a consistently high density of schooling fish. For a more quantitative analysis, a 2015 study conducted in the Sikka Regency of Indonesia determined via hydro acoustic survey techniques that fish biomass in the 1-10 metre range was around 12 tons/Km while in the 11-20 metre range the fish biomass jumped to 2,008 tons/Km. These figures are impressive, and although the fish density has not yet been measured with the same method in Raja Ampat, it is known to seasonally harbour far more fish than the Sikka Regency. But why are there so many fish here? In short, the water is warm and extremely nutrient rich because of an incredibly strong current system that constantly flushes the area with water from the Pacific Ocean. This extremely strong current serves as an important heat exchange mechanism that never allows water to stagnate, effectively buffering the area from the impacts of climate change. But this is no ordinary current. This is one of the strongest currents on the planet.
It is called the Indonesian Throughflow, and it vigorously channels water down from the Pacific Ocean to the Indian Ocean through the straights that separate the landmasses of Indonesia. As a result of trade winds and their associated oceanic currents that run in opposite directions in the two hemispheres, the Pacific Ocean is 15 centimetres higher than the average sea level, while the Indian Ocean lies 15 centimetres below this average. This strong gradient creates a flow pattern that is the oceanic equivalent of pouring a bucket of water down a slide. But instead of a bucket, this is a volume of water equal to all the rivers on Earth combined, and this unimaginable amount of water flows through the marine waterways of Raja Ampat every single second. Due to the impossibility of grasping such a vast amount of liquid, Norwegian scientist, Harald Sverdrup, came up with a new unit of measurement so people could discuss huge, moving volumes in a clearer way. The “Sverdrup” is equal to one million cubic meters of water per second. One explanation recommends visualizing “a river that is 100 metres wide, 10 metres deep and flows at speeds of 4 knots, then imagine 500 of those rivers all combined together.” This is the approximate equivalent of one Sverdrup. The volume of seawater estimated to pass through the Indonesian Throughflow is about 22 Sverdrups! This is still nearly impossible to comprehend, but it is the reason that this part of the Coral Triangle is the richest area of fish biodiversity and biomass in the world.
The water of the Indonesian Throughflow carries with it untold millions of eggs and larvae that supply the region with both genetic diversity and food. Additionally, this gigantic volume of water flow creates upwellings that bring nutrient rich detritus up from the deep offshore basins around Bali. The Throughflow is the strongest during the monsoon season (June-August) and currents are known to reach eight knots.
But it is not just the Indonesian Throughflow we have to thank for the astounding diversity here. It is also a result of the deepwater basins that surround the entire Coral Triangle. These basins have served as a barrier to environmental change throughout a substantial part of Earth’s geological history, shielding the Coral Triangle region from encroaching glaciers during our planet’s ice ages. Since cooling was mitigated by the protection of deepwater trenches, there was never a temperature-induced reduction in species diversity, meaning that life has continued to proliferate for millions of years, unchecked by cold water. Conversely, these trenches also protect the Coral Triangle, and Raja Ampat in particular, from rising temperatures. In the midst of unprecedented levels of coral bleaching on Australia’s Great Barrier Reef, the reefs of the Bird’s Head Seascape have remained relatively untouched.
But this certainly is not to say that the water temperature does not fluctuate. Actually, the large, regular variations in water temperature are one of the factors that make this region so resilient to climate change. A study by Dr. Mark Erdmann of Conservation International that has spanned the last decade showed that the reefs of Raja Ampat “experience temperatures fluctuating between 19 and 36 degrees Celsius (66–96 degrees Fahrenheit), with many individual reefs exposed to a whopping 6–12 C variation within a single 24-hour period!” It seems that these drastic temperature swings serve to “pre-adapt” corals to climate change in the sense that the normal environmental conditions for the area have already selected for the strongest, most resilient specimens. The almost complete absence of bleached corals means that there is no habitat loss and the entire ecosystem continues to thrive. The key here is that even though the marine life is subjected to gigantic changes in temperature, the strong current ensures that these conditions never persist long enough to cause significant harm.
Raja Ampat’s nutrient rich water and ripping currents are not only conditions that foster marine biodiversity and proliferation, but they also draw in pelagics. Manta rays and whale sharks, some of our ocean’s biggest planktivores, come here to feed, another major draw for divers and photographers. Understanding the importance of these animals to tourism, Raja Ampat has been a pioneer for conservation initiatives across Indonesia. 2013 saw the creation of Indonesia’s first shark and ray sanctuary, establishing a no fishing zone for these species covering the entire 46,000 square kilometer area of Raja Ampat. In a part of the world where sharks are mercilessly hunted for their fins and mantas for their gill rakers, sanctuaries like this one are critical to the survival of these animals. Their government has also created a network of Marine Protected Areas (MPAs) throughout the region as well as the groundbreaking Misool No-Take Zone in the south. This no-take zone has been expanding and now encompasses an area of 1,220 square kilometers where the killing, capture, or removal of any wildlife is strictly prohibited. This rapid progress towards protection is particularly inspiring considering the history of the region as a scene of destructive overfishing that severely threatened elasmobranchs, sea turtles, dugongs, and fish species critical to the subsistence lifestyles of many indigenous peoples. Raja Ampat is a prime example of what must be repeated throughout Indo-Pacific waters if we are to save marine life and help rebuild their populations to healthy levels.
Most of Raja Ampat appears pristine and completely untouched, but this is not entirely the case. It is important to remember that even this protected, secluded region of the Coral Triangle is subject to the pressures of human development. Illegal, unreported, and unregulated fishing still occur here and land-based activities such as forestry, coastal development, and poorly regulated mining threaten the health of sea grass beds and fringing reefs. Declining water quality has been measured in more than one region and fish stocks have dropped in other areas. While Raja Ampat is still one of the healthiest reef ecosystems on Earth, it too has felt the undeniable effects of anthropogenic change.
So many factors, both environmental and political, have united to make Raja Ampat one of the most beautiful place on our planet. It is easy to see why Raja Ampat is the crown jewel of the Coral Triangle. While completely worth the effort, the diving conditions in Raja can be a bit tough. The life-giving current that nourishes Indonesia’s seas can make it an extremely challenging place to dive. The current changes like the flip of a switch and the tidal fluctuations are dramatic, especially considering how close it is to the equator. But the exact qualities of the water that make the diving difficult are the same ones responsible for the explosion of marine life in the Bird’s Head Seascape. The coral cover is dense, healthy and varied, making the seascapes in the region amazingly lush and vibrant, and the quantity of fish life never ceases to amaze. Manta rays swoop through protected waters, hovering over cleaning stations to be serviced by wrasses, while pygmy seahorses of several species hide among the sanctuary of their living homes. Schools of silversides well over a million strong blanket the underwater landscape, while lionfish patiently wait to fill their bottomless stomachs with these shiny delicacies. Schools of huge bumphead parrotfish patrol the reefs, scraping algae and eating coral, all the while producing the sand that makes up Raja Ampat’s beaches.
From the bright green, tree-covered islands filled with parrots and butterflies dotting the turquoise waters, to the explosion of all manner of marine creatures beneath the unpredictable waves, Raja Ampat is a rainbow of life. From red to violet without missing any colour in between, this unique part of the world represents the full spectrum of life that can be found in the pristine waters of Raja Ampat. As the name suggests, experiencing the “Four Kings” leaves one feeling like royalty and with a strong desire to discover more of what this kingdom of fishes has to offer.
by Alex Rose with pictures by Alex Rose and Michael AW ( OG 39)