Raroia, Tuamotu Archipelago, French Polynesia
The National Geographic Endeavour, a vessel with a deep, narrow draft and high bow, is aptly suited to take on some of the toughest seas which King Neptune can usher forth. The previous night and throughout the morning he had thrown us a steady diet of winds and swells funneled straight through our front quarter, but our vessel weathered the barrage with little difficulty. The morning was warm and sunny with a few clouds occasionally breaking the steady penetration of the tropical sun’s rays. With our vessel’s back decks sheltered from the easterly winds, most of us found time to lounge upon them, engaging in the languid activities of sunbathing, reading, and resting.
Around mid-day the low-lying, coconut palm-covered, broken islets of Raroia Atoll became defined. Far from giving adequate cover from the prevailing winds, the shoreline of these thin coralline slabs was awash in breakers and salt spray. And the channel into the atoll’s lagoon was choked with sizeable standing waves, the result of the lagoon’s great outwash colliding with an incoming tide. Just off Raroia’s newly-constructed airport on the islet’s ocean side, the staff anchored the snorkel platform in a small cove cloaked with some degree of protection from the winds and swells.
The site was just over the edge of a sloping drop-off, and rich with hard corals. Catastrophes such as storms or massive increases in silt deposition leave an obvious swath of destruction on any reef. It was heartening to see that just off the airport the reef appeared to have suffered no ill-effects from the recent nearby construction. However, small-scale destruction of coral polyps is an everyday event on the reef. In fact, it is an ever-continuing natural drama – dynamic and ceaseless.
It was educational to witness upon closer inspection the results of the natural interplay between reef organisms, which daily wage their own brand of war. As in any ecosystem, every reef organism vies with every other for food, protection, and survival. Nothing that happens on the reef is accidental. The scattered distribution of one or another species of coral, fish, or alga may appear to be a random phenomenon. Further observation reveals the contrary. Every organism is located according to some grand design. The design is not a vast mosaic where every detail is precisely planned. Rather, it is manifested in the creation of narrow niches into which only certain species will fit.
When polyps are destroyed by a predator, a small area of skeleton is exposed. This break can be repaired if the coral head has enough energy and the area is not large. Small coral heads grow rapidly compared to older, larger colonies, but they have relatively little energy to repair torn tissue resulting from the attack of a predator. Large heads may receive too many wounds to be able to repair in a short time. Once the skeleton has lost its thin cover of living coral tissue, it is vulnerable to colonization by a number of organisms. Algae and sponges will settle wherever a hard surface appears. Some of these are burrowing forms and will begin to penetrate the coral head. Feeding on coral is usually done by browsing, more like cattle feeding on grass than predators attacking animal prey. This is advantageous to the coral because this feeding behavior tends to be spotty, leaving a white scar here and there on the surface of the coral head. As a result, living coral tissue has an opportunity to grow back over the area before colonization by sponges or algae begins. It normally takes 2-3 months to repair the damage. Such spots were much in evidence as we duck-dived and swam down for closer inspections of the reef.
On the surfaces of corals and between various coral branches and indeed all over the coral heads this interplay was in full swing. Encrusting fire corals (not true corals at all, but organisms with powerful stings nonetheless) waging a slow battle with true corals, reef fish – carnivorous and herbivorous – briskly feeding on polyps and algae, colorful burrowing marine worms in coral heads, and small crustaceans plucking polyps from their cups were just a few of the players we witnessed on this grand and healthy competitive stage. A few white-tip and black-tip reef sharks let us know that not all reef competition is carried out on a small-scale.
In the late afternoon we rode Zodiacs across Raroia’s turbulent passage to the small islet of Tenukuhaupapatea. The islet’s single resident, a kindly but solitary Frenchman unaccustomed to large crowds, temporarily left in his skiff for lagoon parts unknown. We perused the islet’s northern reaches gazing at the abundance of nesting noddies and white terns. The sky above us and the branches of low shrubs near us were alive with birds. All of us were afforded intimate views of these skies’ most conspicuous denizens. With dusk drawing nigh we returned to our mother vessel across the gauntlet of standing waves. Setting sail to the east, a lazy orange sun sank behind the clouds and crowned the horizon with orange fire.
The National Geographic Endeavour, a vessel with a deep, narrow draft and high bow, is aptly suited to take on some of the toughest seas which King Neptune can usher forth. The previous night and throughout the morning he had thrown us a steady diet of winds and swells funneled straight through our front quarter, but our vessel weathered the barrage with little difficulty. The morning was warm and sunny with a few clouds occasionally breaking the steady penetration of the tropical sun’s rays. With our vessel’s back decks sheltered from the easterly winds, most of us found time to lounge upon them, engaging in the languid activities of sunbathing, reading, and resting.
Around mid-day the low-lying, coconut palm-covered, broken islets of Raroia Atoll became defined. Far from giving adequate cover from the prevailing winds, the shoreline of these thin coralline slabs was awash in breakers and salt spray. And the channel into the atoll’s lagoon was choked with sizeable standing waves, the result of the lagoon’s great outwash colliding with an incoming tide. Just off Raroia’s newly-constructed airport on the islet’s ocean side, the staff anchored the snorkel platform in a small cove cloaked with some degree of protection from the winds and swells.
The site was just over the edge of a sloping drop-off, and rich with hard corals. Catastrophes such as storms or massive increases in silt deposition leave an obvious swath of destruction on any reef. It was heartening to see that just off the airport the reef appeared to have suffered no ill-effects from the recent nearby construction. However, small-scale destruction of coral polyps is an everyday event on the reef. In fact, it is an ever-continuing natural drama – dynamic and ceaseless.
It was educational to witness upon closer inspection the results of the natural interplay between reef organisms, which daily wage their own brand of war. As in any ecosystem, every reef organism vies with every other for food, protection, and survival. Nothing that happens on the reef is accidental. The scattered distribution of one or another species of coral, fish, or alga may appear to be a random phenomenon. Further observation reveals the contrary. Every organism is located according to some grand design. The design is not a vast mosaic where every detail is precisely planned. Rather, it is manifested in the creation of narrow niches into which only certain species will fit.
When polyps are destroyed by a predator, a small area of skeleton is exposed. This break can be repaired if the coral head has enough energy and the area is not large. Small coral heads grow rapidly compared to older, larger colonies, but they have relatively little energy to repair torn tissue resulting from the attack of a predator. Large heads may receive too many wounds to be able to repair in a short time. Once the skeleton has lost its thin cover of living coral tissue, it is vulnerable to colonization by a number of organisms. Algae and sponges will settle wherever a hard surface appears. Some of these are burrowing forms and will begin to penetrate the coral head. Feeding on coral is usually done by browsing, more like cattle feeding on grass than predators attacking animal prey. This is advantageous to the coral because this feeding behavior tends to be spotty, leaving a white scar here and there on the surface of the coral head. As a result, living coral tissue has an opportunity to grow back over the area before colonization by sponges or algae begins. It normally takes 2-3 months to repair the damage. Such spots were much in evidence as we duck-dived and swam down for closer inspections of the reef.
On the surfaces of corals and between various coral branches and indeed all over the coral heads this interplay was in full swing. Encrusting fire corals (not true corals at all, but organisms with powerful stings nonetheless) waging a slow battle with true corals, reef fish – carnivorous and herbivorous – briskly feeding on polyps and algae, colorful burrowing marine worms in coral heads, and small crustaceans plucking polyps from their cups were just a few of the players we witnessed on this grand and healthy competitive stage. A few white-tip and black-tip reef sharks let us know that not all reef competition is carried out on a small-scale.
In the late afternoon we rode Zodiacs across Raroia’s turbulent passage to the small islet of Tenukuhaupapatea. The islet’s single resident, a kindly but solitary Frenchman unaccustomed to large crowds, temporarily left in his skiff for lagoon parts unknown. We perused the islet’s northern reaches gazing at the abundance of nesting noddies and white terns. The sky above us and the branches of low shrubs near us were alive with birds. All of us were afforded intimate views of these skies’ most conspicuous denizens. With dusk drawing nigh we returned to our mother vessel across the gauntlet of standing waves. Setting sail to the east, a lazy orange sun sank behind the clouds and crowned the horizon with orange fire.
