Volume 13, Number 2, 2005
Seven years’ worth of data from coral reefs in an area stretching one-quarter the circumference of the globe has yielded “astounding” results that document a level of diversity far beyond expectations, according to Ronald H. Karlson, professor
of biological sciences.
“Previously published work suggested there was a limit to local species richness,” Karlson says. “Our data clearly show that there is no such limit. At our richest sites, there were four times as many species in local communities as we expected.”
The research was conducted by a team from UD and James Cook University in Townsville, Australia. Karlson, who made a presentation at the 2004 International Coral Reef Symposium in Okinawa, Japan, says the study was undertaken to characterize local species richness of corals in reef flat, crest and slope environments.
Coral reefs and rain forests, he says, have the richest diversity of life on Earth.
The researchers also wanted to characterize regional richness, something that had not been done before, he says, and to consider the relationship between local and regional richness across a vast expanse of the Pacific from French Polynesia in the east to Indonesia in the west.
The science of ecology has tended to focus on local issues, Karlson says, but that emphasis has been changing in the past decade or so.
“There’s been a re-emergence of interest in looking at large-scale ecology,” he says. “We’re beginning to appreciate the importance of looking beyond the local scale.”
Developing a more accurate understanding of coral reef ecosystems is of vital importance, Karlson says, because the world’s reefs are under assault by threats from such human impacts as global warming, forestry practices that cause sedimentation, pollution and overfishing. Because reefs are located close to shore, they are especially susceptible to the effects of what happens on land as the result of development and other practices.
The researchers’ findings show that the preservation of coral reef ecosystems is going to require a regional perspective because the problems are beyond local solutions, Karlson says.
A portion of the research, which concerned regional enrichment of coral communities, was featured in a letter in the scientific journal Nature, which had as its cover story “Coral Reefs in Crisis.” In the letter, the research team notes that the study was of unprecedented geographical scope, with samples taken along a narrow strip covering about one-quarter of the circumference of the Earth.
“Local coral assemblages are embedded in regions with different histories, geographies and human influences, and they are influenced jointly by both local and regional factors,” the researchers wrote. “Recent assessments of the status of coral reefs verify that they are globally threatened, and efforts to manage them will require international cooperation.
“As most conservation efforts by policy makers and managers begin with attempts to preserve local coral reefs, it is imperative that we learn how coral communities function at these local, ecologically important scales while maintaining a regional perspective.”
Worldwide, the degradation of coral reefs “is a severe problem, and it’s fairly pervasive,” Karlson says. “There may be some short-term conflicts between economic and environmental issues, but they’re tied together in the long term, so we need to get to work.”
Karlson says the project has been “something you dream of” as a researcher, one that has taken the team to a variety of tropical locales.
While working at a remote diving camp in Indonesia’s Irian Jaya, the scientists learned that the famous English naturalist Alfred Russel Wallace had stayed in a nearby village while conducting research in the 19th Century. It was Wallace who developed the dividing line between two major zoogeographic regions, the Oriental and the Australian.
The coral reef project has received funding from the Australian Research Council, the National Science Foundation and the National Geographic Society.
—Neil Thomas, AS ’76