The late 17th century sea-farers who used the mysterious sound of gigantic swimming turtles to navigate around coral reefs would find these same reef ecosystems significantly changed for the worse today. In another 30 or 40 years, the same reefs could be almost completely destroyed, unless humans act now to aggressively protect them from further human exploitation, scientists say.
The 15 August issue of the journal Science published by AAAS, the science society, features a special report on coral reefs. All sorts of records, from pirate’s logs to modern day fish counts, reveal that humans have a long history of damaging reefs. Based on this history, humans have one last chance to establish a sustainable reef-protection strategy, according to the authors.
A timeline of decline
Humans have been steadily damaging coral reefs since the hunter-gatherer era of human history. Overfishing and pollution run-off from land are not exclusively modern problems, according to one of the four Science articles. These authors report that destructive and poisoning practices are to blame for the steady decline in coral reefs that began with ancient humans.
Researchers led by John Pandolfi from the National Museum of Natural History, Smithsonian Institution in Washington laid out a timeline of human history going from hunter-gatherers to the modern era. For each of seven culturally defined periods from pre-human to present, the researchers plotted the level of coral reef degradation.
Information from the earliest human interactions with reefs came from fossil and archaeological records. Records and logs from the ships of Christopher Columbus, Captain James Cooke and other European explorers provided detailed descriptions of abundance and diversity of coral reef ecosystems they encountered. From more recent eras, the researchers used data from fisheries and modern ecological studies.
Large animals declined faster than small animals, the researchers found. Free-living animals declined faster than the architectural builders such as seagrass and corals. At the beginning of the 20th Century, large carnivores, including sharks, and herbivores such as manatees were already either depleted or rare in 80 percent of the examined regions of coral reefs.
“Walking the plank isn’t as dangerous as it once was,” said John Pandolfi, an author on two of the Science papers and a curator at the National Museum of Natural History, Smithsonian Institution.
“If I was forced to walk the plank and jump into the Caribbean tomorrow, it wouldn’t be that bad. Of course there is the risk of drowning, but it’s not like the old days when the risk of being eaten by sharks was so much greater,” explained Pandolfi.
While the ecological histories show that coral reefs have been declining ever since humans discovered their bounty, Pandolfi is not all gloom and doom, in his attitude or his predictions but believes there is some hope for the future. However, a co-ordinated, aggressive, worldwide effort must be implemented soon.
Coral reefs and friends
A coral reef’s bright colors come from the single-celled algae called “zooxanthellae” that have a cooperative living arrangement with corals. These colorful, primitive plants use the sun to produce food that they share with the coral in return for shelter.
Coral reefs grow in the warm, shallow, clear waters of about 100 tropical and subtropical countries. Reefs provide food and shelter for fish and invertebrates critical to commercial fisheries. They also protect nearby shorelines from erosion and attract the tourists that sustain economies.
Invertebrate animals called corals build the reefs that bear their name. Corals secrete the limestone that forms the hard structure of coral reefs.
While the building of coral reefs takes many years, storms and human activities can rapidly destroy them. Reefs that are already stressed by pollution and over-fishing have a harder time rebounding from natural occurrences such as hurricanes and cyclones.
The future of coral reefs depends on how well humans reduce the pressures of over-fishing and pollution while minimizing the already catastrophic impact of ocean warming on coral reefs. The authors of a second Science study note that some coral species are showing far greater tolerance to climate change than others.
Declining standards for coral reefs
“People pay hundreds of dollars to dive in reefs so damaged that seeing them would make me cry,” said Jeremy Jackson, an author on the two Science papers described in this story.
“They have no idea what they are missing or what drastic deterioration has occurred,” said Jackson, a marine biologist from Scripps Institution of Oceanography in La Jolla, CA and the Smithsonian Tropical Research Institute in Balboa, Republic of Panama.
The ecosystem histories the marine biologists just published are, in some ways, the equivalent to a person’s medical records, according to Jackson. He noted that people often try to address the problems facing coral reefs today without understanding the history of the problem.
“Doctors would be sued for malpractice if they diagnosed patients the way many scientists are diagnosing oceans,” said Jackson, referring to the practice of trying to solve ocean problems using current data alone.
Protect now, snorkel later
“If we can get something in place in the next ten years, we can bring many of these fish stocks back. Fish stocks have a great capacity for resiliency. All is not lost,” said Pandolfi.
Pandolfi is not calling for the restoration of all the world’s reefs to their pristine, unaltered state, he said. Instead, he hopes his data will call attention to the critical situation facing coral reefs.
“We need massive coordination at every level from grassroots movements to governments to international non-governmental organizations,” said Pandolfi.
“For example, if the Honduran government bans fishing in part of a reef, what is going to prevent Hondurans from crossing the invisible border and fishing on the Nicaraguan side of the reef? There has to be coordination so that a country that tries to implement a reef protection plan is not placed at a disadvantage in relation to its neighbours,” Pandolfi explained.
Pandolfi noted that the new timeline of coral reef destruction helped the scientists formulate reef management recommendations.
Among the recommendations are reef preserves called “no-take areas,” international coordination, and reef restoration.
These historical analyses provide a baseline that doesn’t shift and it helps to put the current crises into perspective, said Pandolfi.
“We are a fundamentally a historical culture. By ignoring history we can not solve the problems that we think we understand by looking at the present,” said Jackson.