Source: The Royal Gazette Green Pages
Colonies of corals build reefs. As stony corals construct new animals on top of themselves, the lower sections die. The skeletons of these hard corals form the structure of the reef. Sand fills in the framework and calcareous algae cements it.
Live corals covered more than 50 percent of Caribbean reefs in the 1970s. Compare that to the eight percent in 2011. Is the ecosystem on the verge of collapse?
According to research by the World Resources Institute (WRI), the dearth of coral growth has endangered 75 percent of Caribbean reefs, 95 percent of Southeast Asian reefs, and by 2050 would imperil almost all coral reefs, globally.
Reefs have been called the ‘rainforests of the sea’. Like land-based forests, the ocean absorbs excess carbon dioxide from our atmosphere. The CO2 is concentrated in surface waters. It doesn’t mix with water at depth, thereby increasing acidity in shallower regions. Such changing water chemistry appears to be interfering with the rate at which corals lay down their skeletons and perhaps even contributes to the death of the corals.
But Dr Eric J Hochberg, oceanographer specialising in coral reef ecology and associate scientist at the Bermuda Institute for Ocean Sciences (BIOS) said: “Neither lab nor field studies show mortality from ocean acidification, only a slowing of growth.”
Such acidification is among a myriad of challenges the coral animals face in their seawater habitat. Climate change, a warming ocean and rising seas feature in the list of severe environmental problems. These, coupled with overfishing, pollution and in the Atlantic invasive Lionfish, could lead to destructive domino effects.
At the International Coral Reef Symposium in Cairns, according to the Guardian newspaper, NOAA chief, Jane Lubchenco said: “We’ve got sort of the perfect storm of stressors from multiple places really hammering reefs around the world. It’s a very serious situation.”
Lose the reefs, you lose the reef fish, the 25 percent of all marine fish species that depend upon its recesses to act as nurseries for juveniles, and safe harbour for adults. You lose the natural barriers that protect islands like Bermuda and fragile coastlines elsewhere from tidal waves.
By comparison to reefs elsewhere, Bermuda’s appear healthy. But ‘healthy’ is a subjective term, according to Dr Hochberg.
He said: “Bermuda has higher coral cover than reefs in the Caribbean, but Bermuda also has much lower diversity both corals and fish than Caribbean reefs. So Bermuda’s reefs are well in one aspect, but poor in another. At the ecosystem scale, my professional opinion is that Bermuda’s reef system is not actively accreting (maintaining itself at sea level). Rather, the reef here is a collection of reef communities living on top of the flooded Bermuda platform.
“Since Bermuda is so far north, winter temperatures and light levels drop too low for reef development. It’s possible that a warming ocean will help Bermuda’s reefs to begin more active accretion. This would be vital in a world of rising sea levels.”
Dr Hochberg continued: “Lionfish are a real problem… The best we can do is encourage their widespread harvest, with the hope of controlling their population growth.”
The resident scientist noted that Bermuda doesn’t experience high levels of fishing pressure, nor because of its small landmass, does it discharge much sediment onto the reefs. The Island is mid-Atlantic, its seas extremely clear. Water continuously washes its platform.
Dr Hochberg said: “There is no doubt that reefs are under threat, but I tend to think the threat is overstated. While scientists have seen declines, they have also begun to see recoveries in many locales. Reefs are dynamic systems, and we should not expect them to remain static. In fact, a very good sign of a healthy reef would be recovery after a disturbance.”
According to WRI’s Lauretta Burke, lead author of Reefs at Risk, coral reefs’ resilience helps them rebound if local pressures ease, but Herculean efforts are required for any real reversal.
As a people, Bermudians can help the world eliminate the green house gases that threaten our atmosphere and oceans by investing in solar, wind and wave power.
Locally, also, we can enforce stringent catch quotas and educate our children about not touching or standing on the live animals that make up our reefs.
Genuine cause for concern exists, but Dr Hochberg views our reefs in a positive light.
“We have a great deal of hope,” he said. “Bermuda’s reef ecosystem… (has) existed since the end of the last glaciation, about 7,000 years ago. If we continue to have rational, reasonable stewardship of our reef resources, any ecosystem decline would not be due to local causes.”