sábado, 22 de octubre de 2011

Environment - Ocean's garbage content appalls bird researchers

From their nests in the sand on tiny atolls in the northwestern Hawaiian Islands, Black-footed albatross fly 2,800 miles to the food-rich waters off the Sonoma coast. 

From their nests in the sand on tiny atolls in the northwestern Hawaiian Islands, Black-footed albatross fly 2,800 miles to the food-rich waters off the Sonoma coast [Credit: Press Democrat]

But the vital nourishment the big ocean birds regurgitate for their chicks back in Hawaii is laced with plastic fragments, bags and fishing line, as well as cigarette lighters, toothbrushes, toy soldiers and syringes scavenged from the ocean surface. 

“We're all really appalled by what we find,” said David Hyrenbach, an Oahu-based oceanographer with Oikonos, a nonprofit environmental organization. 

Plastic refuse turns up in the stomachs of every dead albatross chick and in all the pellets vomited up by live chicks and found by researchers, he said. 

The albatross' experience mirrors both the biological wealth of the local coast and the increasing human impact on ocean waters, including pollution and climate change. 

“For so many years, the ocean was thought of as a good place to get rid of stuff,” said Dan Howard, superintendent of the Cordell Bank National Marine Sanctuary. 

Discovery of the Great Pacific Garbage Patch in the late 1990s — comprised mostly of tiny plastic particles suspended in the water — proved the ocean's unsuitability as a trash can. 

Scientists are attempting to trace the origin of plastics found in the Hawaiian albatross, and its possible impact on mortality of the endangered seabird, Hyrenbach said. 

Closer to home, experts are assessing two impacts of climate change on one of the world's most abundant marine ecosystems: ocean acidification and a change in the wind. 

So far, the Sonoma Coast — considered part of the Greater Gulf of the Farallones — is doing well, owing largely to the coast's sparse population, which minimizes land-based pollution. 

“We're very fortunate in this area,” Howard said, contrasting Sonoma with Southern California, where beaches are occasionally closed because of sewage spills. 

A 60-page report on the Cordell Bank sanctuary rated water quality good (the top rating) and other conditions, including habitat and “living resources,” as fair or better in the sanctuary, a 529-square-mile protected area off the coast from Bodega Head to Point Reyes. 

The status of key species in the area “appears to reflect pristine or near-pristine conditions,” the report said, noting that the over-harvested rockfish populations appear to be rebounding as a result of conservation measures. 

Humpback and blue whales, seals and sea lions and dozens of bird species, including long-distance fliers like the albatross, flock to the Sonoma Coast, a marine cornucopia owing to a phenomenon called upwelling. 

“There is always food, like a big Serengeti Plain,” said John Largier, professor of oceanography at the Bodega Marine Laboratory, a UC Davis research facility perched on the coast next to Bodega Head. 

Point Arena, 60 miles to the north, forms a center in the coastal upwelling system that brings a “persistent fountain” of cold, nutrient-rich waters from the deep ocean to the sunlit shallows, Largier said. 

It takes five days for the prevailing north wind to push that water south to Bodega Head, loaded by the time it arrives with a mass of nutrient-fed phytoplankton. These microscopic plants, mostly diatoms, form the base of the marine food web serving everything from half-inch invertebrates to 200-ton whales. 

It's a perfect biological scenario, but one that may need to adapt to climate change. 

Offshore buoys have detected a slow increase in wind speed — the driving force behind the upwelling — over the past 30 years, Largier said. Blowing predominantly from the north, the frictional drag of the wind pushes surface waters offshore, drawing up cold water from below 

Stronger winds will strengthen the upwelling, driving plankton-enriched water farther offshore, diminishing its support of coastal marine life, he said. 

“Too much wind is probably not a good thing,” Largier said. Scientists have not determined if the stronger wind is part of a natural cycle or a worrisome climatic trend, he said. 

Meanwhile, biologists monitoring seabird reproduction on the Farallon Islands for 40 years reported the worst year in 2005 and the best year in 2010, both related to fluctuations in the strength of the upwelling. 

Such a dramatic shift in just five years appears to match climate-change models that predict “greater variability” in ocean conditions as the planet's temperature rises, Howard said. 

“It's certainly something worth paying attention to,” he said. 

Scientists are also watching ocean acidification, a consequence of increased carbon dioxide in the atmosphere and the likely cause of poor reproduction at oyster farms in Washington state, he said. 

There are indications of increased acidification on the Sonoma Coast, but no negative impacts have been observed, Howard said. 

He and Largier agree that climate change could dramatically alter the region's marine ecosystem, with varying results for the native species. 

“There will be some winners and some losers,” Largier said. 

The Press Democrat 

Source: The Archaeology News Network

No hay comentarios:

Publicar un comentario