Photo: Brian Skerry / National Geographic
Ecologist Enric Sala found a 500-year-old gigantic lobe coral in the Kingman Reef that looks like a flying saucer (the species is likely to be new to science).
In the Pacific atolls and islands, there is a 30-mile triangle of coral in a lagoon the size of Manhattan Island called the Kingman Reef. Because of its remoteness, the reef is pristine, "a glittering city of staghorn, mushroom, pillar, and plate corals packed so tightly together there is hardly a patch of bare sand." Small fish and large predators are abound, making it a true underwater Eden.
But the image of a fluorishing and healthy ecosystem may be just a mirage. According to ecologist Enric Sala, Kingman Reef may actually be in big trouble and the culprit is overfishing and pollution:
If predator-dominated Kingman represents the gold standard for coral reefs, how does the removal of large carnivores through fishing affect coral communities elsewhere, such as in Kiritimati? As the report from the Line Islands shows, overfishing can unleash a population boom of smaller fish. The reef might appear luxuriant for a time, but in a matter of decades its ecosystem can unravel from a wonderland of marine diversity into a sediment-choked ecological desert.
"Eliminating the top predators speeds the turnover rate of the entire reef community," Sala says. Through mechanisms not yet fully understood, this acceleration ultimately produces an explosion of microbes, some of which may cause coral death. Fishing out the large herbivores contributes to reef degradation. In the absence of grazers, large algae flourish, and their photosynthetic activity increases the availability of dissolved organic carbon in the system, boosting the growth of bacteria.