Death bloom of plankton a warning on warming

(11-20) 20:27 PST -- Vanishing Arctic sea ice brought on by climate change is causing the crucially important microscopic marine plants called phytoplankton to bloom explosively and die away as never before, a phenomenon that is likely to create havoc among migratory creatures that rely on the ocean for food, Stanford scientists have found.

---

A few organisms may benefit from this disruption of the Arctic's fragile ecology, but a variety of animals, from gray whales to seabirds, will suffer, said Stanford biological oceanographer Kevin R. Arrigo.

Phytoplankton throughout the world's oceans is the crucial nutrient at the base of the food web on which all marine life depends; when it's plentiful, life thrives and when it's gone, marine life is impossible.

 Arrigo and his colleagues gathered 10 years of observations from six NASA satellites to study changes in the evidence of chlorophyll - a key to measuring the annual abundance and disappearance of phytoplankton blooms - at the surface of the oceans

A report of their findings is to appear in the current issue of the journal Geophysical Research Letters.

The annual deep freeze that has covered much of the northern seas with ice around the polar regions was once a regular event, but what has been normal for millennia in the High Arctic is no longer the case. As global climate change has warmed the world's oceans, warmer water has moved into the frigid Arctic, causing changes in the once-regular appearance and disappearance of sea ice over vast areas.

The result is a shift in when explosive blooms of phytoplankton appear and disappear, Arrigo's team has found.

"It's a complex system," Arrigo said in an interview, "but as the changes in ice cover throw the timing of phytoplankton abundance off, then the birds and animals whose brains have long been programmed to migrate north at specific times of the year will have missed the boat if there's no nourishment for them when they get there."

Some fish and other creatures in the far north that serve as prey for animals higher in the food chain may benefit from increases in phytoplankton, but many migratory animals like gray whales and all the seabirds that shuttle to the Arctic at fixed times are bound to lose out if the timing of the phytoplankton cycle changes, Arrigo said.

His colleagues in this report are Gert van Dijken, the project's technical expert, and Sudeshna Pabi, a geophysics graduate student at Stanford.

Full Story