July 16, 2012,
La possibilita’ di successo a livello globale e’ minima, ma l’esperienza descritta dimostra quanta influenza eserciti l’azione umana sulla vita marina.
L’articolo del NYTimes si occupa solo del problema di overfishing, cioe’ solo del “pescare riducendo via via la capacita’ di rigenerazione”; non parla di acidificazione del mare, ne’ di inquinamento.
Overfishing, Acidificazione e Inquinamento sono tre fattori che in sinergia e in aumento continuo implicano la fine della vita marina come la conosciamo.While the chance of success at global level is very small, this experience shows how human action influences marine environment. It only deals with the problem of overfishing, not acidification nor pollution: these three factors combined promise to be the end of sea life as we know it.
July 16, 2012,
When Coral Reefs Recover
By MELISSA GASKILL
Fish biomass increased more than fivefold after a marine reserve with a fishing ban was established off Cabo Pulmo, Mexico. Nearby fisheries benefited, too.Gerard Burkhart for The New York TimesFish biomass increased more than fivefold after a marine reserve with a fishing ban was established off Cabo Pulmo, Mexico. Nearby fisheries benefited, too.
It turns out that the way to protect coral reefs is to, well, protect them.
That was the core message of several presentations at an international symposium on coral reefs that wrapped up on Friday in Cairns, Australia.
Ocean acidification, warming water temperatures, pollution and overfishing pose dire threats to coral reefs worldwide. On the plus side, said John Pandolfi, director of the Center for Marine Science at the University of Queensland, reducing these threats locally can improve reef conditions. The bad news, he adds, is that coral reefs bounce back more slowly than other marine ecosystems like estuaries. So the sooner action is taken, the better.
The overfished reefs at Cabo Pulmo on the eastern Baja California Peninsula. are a case in point.
After the establishment of the Cabo Pulmo National Marine Park — and more
than 10 years of local enforcement of no-take inside its boundaries — the Scripps Institution of Oceanography found that the amount of fish biomass in the protected area had increased more than fivefold, and shark biomass, tenfold. That’s the largest absolute increase in fish biomass ever measured in a marine reserve anywhere in the world.
What is more, the benefits of this kind of protection extend beyond the boundaries of a protected area.
A recent study by the Australian Research Council Center of Excellence for Coral Reef Studies found that marine reserves help restore depleted populations on neighboring reefs. In the Keppel Islands on Australia’s Great Barrier Reef, reserves that cover about 20 percent of the reef area generated half of the baby fish both inside and outside the reserve, researchers said.
Networks of reserves could therefore contribute substantially to the long-term sustainability of coral reef fisheries and put to rest claims that closing areas to fishing harms those who make their living from it. Anecdotal evidence from Cabo Pulmo supports this finding, as fishing has improved outside the protected area.
Other studies have shown that strict enforcement of marine reserves not only helps marine life but can reduce local poverty. Once residents of Cabo Pulmo gave up fishing, they began offering eco-tourism services built around the area’s natural assets, including scuba diving, snorkeling and kayaking. The village now has a higher per-capita income than the Mexican average.
Another insight emerging from the symposium is that reefs in the Indo-Pacific region seem to be more resilient and to recover more quickly than those in the Caribbean. Research presented by George Roff and Peter Mumby of the University of Queensland suggested that this is partly because the Indo-Pacific has less seaweed, which competes with corals for space. The seaweed species there bloom more slowly than their Caribbean counterparts, too.
And the Indo-Pacific has more abundant species of herbivorous fish to keep seaweed in check. So, less competition with seaweed for space means corals can recover more quickly after taking a hit.
Dr. Mumby said that local managers in the Caribbean can seek to maintain healthy parrotfish populations to keep seaweed in check.
Dr. Roff, Dr. Mumby and other researchers at the conference repeatedly warned that the need for action is urgent. If protected, they emphasized, coral reefs will respond.