Vital Marine Plants in Steep Decline

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Vital Marine Plants in Steep Decline

Postby felix dakat » Thu Jul 29, 2010 5:21 am

By GAUTAM NAIK

Rising sea temperatures can harm the tiny plant life that forms the base of the oceans' food chain as well as affect the diversity of marine life, two new studies have found.

In research published Wednesday by the journal Nature, scientists found a strong link between higher sea-surface temperatures and a major decline over the past century in marine algae, or phytoplankton. These microscopic plants generate roughly half of all organic matter—the building block of life—on the planet.

A second study, also published in Nature, concludes that warmer seas can influence marine diversity, potentially rearranging the global distribution of ocean life.

Over the years, humans have affected the oceans by polluting and over-fishing and through habitat alteration caused by dredging and other activities. Less understood is the role of higher sea temperatures. Scientists, many of whom believe the increase to be linked to global climate change, estimate the oceans have warmed by roughly half a degree Celsius on average over the past 100 years.

Phytoplankton has flourished in many coastal areas because increased runoff from rivers brings nutrients that the algae gorge on. But no one has properly assessed whether the global oceans are losing or gaining phytoplankton, which forms the base of the marine food chain, from crustaceans to fish and ultimately to humans.

Consistent satellite-based measurements of the algae exist only from 1997. Scientists at Dalhousie University in Nova Scotia, Canada, instead used data obtained with a simple oceanography device used since the late 1800s known as a Secchi—a disk lowered into the water to measure phytoplankton abundance.

By collating and analyzing about half a million Secchi observations, plus other direct measurements of algae, the Dalhousie team estimated that phytoplankton levels declined by about 1% of the global average each year from 1899 onward. The data are more reliable for recent decades, translating into a 40% decline since 1950.

The team investigated several factors that could have caused the decline. "We found that temperature had the best power to explain the changes," said Boris Worm, a marine biologist at Dalhousie and co-author of the study.

Marine algae live in the upper layers of the ocean but rely on nutrients that circulate up from lower layers. Rising temperatures mean the different layers mix less with each other, so fewer nutrients reach the algae. However, Dr. Worm noted that algal abundance can be affected by other factors, such as shifts in predator-prey populations.

Mike Behrenfeld, an expert on phytoplankton at Oregon State University, said the paper was similar to a 1992 study that used Secchi data to show a long-term decline in marine algae in the north Pacific. "But this paper covers the globe," he said. "And the scientists also took the next step of relating the [algal decline] to sea temperatures."

Another team of scientists mapped the diversity of marine life on a broad scale. The researchers analyzed possible links between the global distribution of 11,000 marine species—big and small—to such factors as temperature, oxygen levels and habitat availability. For all species types, only one factor showed a consistent correlation with diversity: sea temperature.

It isn't clear what this means globally. When water warms, some species may move elsewhere, reducing the diversity of their original habitat. Creatures that can't move may come under environmental stress or die off, also altering the ecosystem.

"While a changing climate is likely to lead to a change in patterns of diversity, we don't have the data yet to know what this response might look like," said Derek P. Tittensor, marine ecologist at Dalhousie and co-author of the second Nature paper.

Printed in The Wall Street Journal, page A4

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Re: Vital Marine Plants in Steep Decline

Postby MagsJ » Sun Aug 01, 2010 2:14 am

Ha, I read about in the Mail-Online - it's just one thing after another after another after another. Will man's need to have such all-encompassing involvement in humanity's progression ultimately lead to the demise of man.
The possibility of anything we can imagine existing is endless and infinite

I haven't got the time to spend the time reading something that is telling me nothing, as I will never be able to get back that time, and I may need it for something at some point in time. Wait! What?

--MagsJ
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Re: Vital Marine Plants in Steep Decline

Postby felix dakat » Sun Aug 01, 2010 5:06 pm

How many warning signs does the human species need before we begin to make serious changes in the way we live?

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Re: Vital Marine Plants in Steep Decline

Postby jonquil » Sun Aug 01, 2010 5:09 pm

What do we care about silly plankton anyway? It only works as a vital part of the food chain and the oxygenization of the atmosphere. Big deal. Food and air are just silly baubles to fill babies' stomachs and rattles with.
"Sur le volcan ne pousse pas l'herbe" (Grass does not grow on a volcano). - Ivor Cutler on his bald pate
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Re: Vital Marine Plants in Steep Decline

Postby felix dakat » Sun Aug 01, 2010 5:21 pm

jonquil wrote:What do we care about silly plankton anyway? It only works as a vital part of the food chain and the oxygenization of the atmosphere. Big deal. Food and air are just silly baubles to fill babies' stomachs and rattles with.


That's the spirit! #-o

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