Published On: Mon, Apr 13th, 2015

Oceans suffer colossal damage

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It only took us an existential moment to damage them, but they won’t be fixed in our lifetime.

Researchers say ocean ecosystems have taken a hit from climate change — and that it could be thousands of years, not hundreds, before they recover. By analysing layers of fossilised ocean fauna, scientists from UC Davis’ Bodega Marine Laboratory and Coastal and Marine Sciences Institute were able to make out correlations between abrupt climate change and disturbances in ocean biodiversity. Their study was published on Tuesday in the Proceedings of the National Academy of Sciences.

Biologically diverse seafloors can lose large amounts of dissolved oxygen as a result of climate change. The process — called deoxygenation — can disrupt the biodiversity of ocean ecosystems. But previous studies did not quantify these disturbances and recoveries in relation to sudden climate change. Led by Sarah Moffitt, a UC Davis research team began by extracting a huge fossil core from the ocean floor off Santa Barbara.

“After the initial sampling at sea, I took the entire core, which was about 30 feet long,” Dr Moffitt said in a statement.

“I cut it up like a cake, and I sampled the whole thing. Because of that, I had the whole record.”

The core contained fossil evidence from a period spanning 16,100 to 3,400 years ago. In that time, Moffitt noticed repeating patterns. Diverse seafloor ecosystems would experience deoxygenation coinciding with warming periods, and rapid loss of diversity would follow. In low-oxygen periods, fossil evidence was minimal. Even minor drops in oxygen levels appeared to curtail undersea life.

And while the warming events seemed to last hundreds of years — possibly only decades — it took ecosystems thousands of years to bounce back. –Agencies


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