An ocean on the slide could hurt us badlyUnited States
Declining “invisible” phytoplankton, which create oxygen and eat the greenhouse gas CO2 need a close look and a possible rescue.
It may be hardest of all to care about something unseen. A single glass of seawater drawn from the surf in Newport or Brookings might look clear but in fact would roil with at least 75 million organisms called phytoplankton.
And we vitally depend upon such creatures. Out in the ocean, infinite numbers of them produce half the world's oxygen and form the base of the marine food chain. For what it's worth, phytoplankton eat crazy amounts of carbon dioxide, a greenhouse gas.
But their numbers are down 40 percent worldwide since the 1950s and may be headed down further. The culprit appears to be rising ocean temperatures associated with climate change. The sea's warming top layer of water, where phytoplankton do their job, increasingly lacks life-sustaining nutrients from the cold deep.
Those are the findings of Canadian researchers published recently in the journal Nature. They need our full attention if we are to respect the oceans as linked to human destiny and want to manage the seas to keep them productive.
Phytoplankton typically get name recognition only during an El Niño weather cycle. That's when their numbers plummet in a disturbed sea, starving and killing large numbers of marine animals and sea birds -- viewable carnage along the Oregon coast, producing a brief but heartfelt response in so many.
But this is no seasonal phenomenon, it turns out. A potentially lethal decline appears to be full time and just below the surface.
The Canadian team aggregated thousands of ocean clarity measurements and observations dating to 1899 and charted phytoplankton declines, worst now in polar and equatorial Pacific and Atlantic waters. This applies to plankton as widely recognized as green algae and as little known as the tiny diatom, so profuse as to fix up to 20 percent of the globe's CO2, by one estimate.
Some years ago Michael Behrenfeld, an Oregon State University professor and specialist in marine algae, viewed a decade's worth of satellite data and demonstrated that warmer surface temperatures in the ocean were tied to decreased photosynthesis -- the real work of phytoplankton.
The new findings, consistent with Behrenfeld's, extend the record further back and strengthen the case that phytoplankton fail in warmer surface water. It's hardly a leap to infer that the fundamental productivity of the oceans is being driven down -- a grim trend line that requires direct attention.
Few things in science, however, are a lock. Implicated is climate change. Are we really going to craft policy on the backs of missing diatoms?
Behrenfeld is clear that the next research step must be to learn the mechanics underlying phytoplankton's failure -- predictions of a continued slide and corrective action are impossible without such knowledge.
We agree. But Behrenfeld, and now the Canadian team, have made utterly persuasive cases that our oceans are in trouble in yet another way needing urgent attention.
The case of the missing phytoplankton is serious business. It goes well beyond overfishing or pollution -- the kinds of things we can see happening.
This challenge is on another scale altogether: Human as well as marine destiny is on the line.
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