As Arctic Ice Melts, Biological Boundaries Between Atlantic & Pacific Disappear - Nature

[hatrack]

The melting of Arctic sea ice is blurring the biological boundaries between Pacific and Atlantic. It was in May 1999, during routine monitoring, that the tiny diatom was first found drifting in the ocean currents. Not an unusual observation on a plankton survey, only the species was in the wrong ocean. The north-west Atlantic was thick with phytoplankton of a Pacific species on its first visit for 800,000 years.

"We were very familiar with the species in the Pacific," says Chris Reid, professor of oceanography at the Sir Alister Hardy Foundation for Ocean Science (SAFHOS) in Plymouth, UK, who led the survey. "But we had never seen it in the Atlantic before — it took a while for us to realise the significance."

EDIT

The true significance of the event lies not in the single species introduction but in a barrier being breached between the two oceans. Viable pathways through the Arctic ice mean that many more Pacific species could follow suit, posing a threat to northern north Atlantic species by competing for resources and potentially playing havoc with the ecosystem.

Although phytoplankton are among the ocean's smallest denizens, their size belies their impact. The phytoplankton species Coscinodiscus wailesii, which invaded the North Sea from the Indian and Pacific Oceans, for example, displaces indigenous species given the right conditions. And as many native phytoplankton feeders find it unpalatable, its presence has knock-on effects throughout the entire food web. "This is the trickle before the flood," says Reid, describing plankton as a "tremendous indicator" of what is happening in the ocean. "We could well see a complete reorganization of the fauna of a large part of the northern north Atlantic."

EDIT

http://www.nature.com/climate/2007/0711/full/climate.2007.61.html

[n2doc]

1. This is part of the scary future

We DO NOT KNOW what all of the effects of climate change will be. And we are doing a heck of a lot of other things that will feed off of these changes. For example, overfishing has led to big changes in zooplankton composition in several coastal regions, typically, more jellyfish and other jelly-like organisms and fewer copepods and other harder bodied animals. How all this fits together is unknown, and how it will interact with food chains, carbon sequestration and other aspects of the environment is also unknown (and not studied since there is little $$$ to study it).