An ambitious expedition led by scientists at Scripps Institution of Oceanography at UC San Diego to a chain of little-known islands in the central Pacific Ocean has yielded an unprecedented wealth of information about coral reefs and threats from human activities.
The exploration of four atolls in the Line Islands, part of a chain approximately a thousand miles south of Hawaii, has produced the first study of coral reefs comprehensively spanning organisms from microbes to sharks. This in-depth description was replicated across a gradient of human impacts, from uninhabited Kingman Reef to Kiritimati, also called Christmas Island, with a population of 5,000 people.
The results are published in two papers in the Public Library of Science (PLoS) ONE (Feb. 27) journal and a companion essay in PLoS Biology (Feb. 26).
At Kingman, the researchers described one of the planets most pristine coral reefs, a resource they say provides a much-needed baseline for the conservation of coral reefs. In one paper, the scientists describe Kingmans atypical food web, where predators such as sharks accounted for 85 percent of the total fish biomass (the weight of all fish together). This inverted pyramid, they say, runs contrary to the bottom-heavy pyramids seen in other parts of the world where top predators have been fished out. Kingman also exhibited healthy coral populations and was nearly absent of seaweed and had low microbe concentrations, unlike evidence found elsewhere on disturbed reefs.
A comparison of Kingman with other reefs in the Line Islands revealed increasing levels of human impacts, including declining coral health, fewer and smaller fish and an increase in microbes.
The Kingman baseline, the researchers say, will be essential for comparisons against degraded reefs elsewhere and for evaluating the efficacy of current conservation actions. They say the data will stimulate new ideas for conserving reefs against threa
|Contact: Mario Aguilera or Annie Reisewitz|
University of California - San Diego