We hear a lot about the upper end of the food chain. In the case of the Arctic, that’s people and polar bears. Declining ice has led to great concern for the bear’s survival and that of a rich northern culture.

But ice or no ice, there’s another factor that the bears—and just about every other Arctic marine animal—depend upon. It’s plankton: tiny plants (called phytoplankton) and animals (called zooplankton) at the very bottom of the food chain. Plankton are an essential link, without which there would be no food chain at all. But what do we know about how plankton will be impacted by the Arctic’s warming climate and potential increased human activities that go with it?

A new study published in the latest edition of the journal Marine Biology asks what impacts the warming ocean and oil extraction activities might have on one of the most significant types of plankton in Arctic seas: small relatives of shrimp called copepods. The study is a strong example of how little we still know about Arctic marine systems at a time when pressure is growing to extract oil and gas, develop new fisheries, increase shipping traffic and other activities.

Copepods are like little batteries that get their energy from feeding on microscopic algae. Fish, birds and even several whale species get their energy by eating the copepods.

But not all copepods are created equal; some species are more energy-rich than others. Areas where lots of high-energy copepods occur can support more animals up the food chain. One such region is in Arctic waters. Extending farther south is another species that is far less-energy rich.

The study involved experiments run by Morten Hjorth and Torkel Gissel Nielsen from Aarhus University and Technical University, respectively, in Denmark.  They were interested in understanding how a northern, energy-rich copepod species and a southern, energy-poor copepod each does as temperatures increase. Might the southern species move north as temperatures increase? If so, could it outcompete the more energy-rich northern species? And given that oil and gas-related activities are likely to increase in the North, what happens if we add oil into the mix? The consequences for the rest of the food chain could be enormous if a less nutritious species of copepod takes over Arctic waters.

These are tough questions that won’t be answered in a single experiment. There remains much more work to be done before there’s enough of a body of work to say much conclusively. The findings are interesting, though, and I’ve written about them in detail here.

But the fact that these questions are being asked at all should tell us something about our level of knowledge of these systems.

Probably the most important message is that we still understand very little about Arctic marine systems and how the changes that are now occurring may impact them. But we understand them enough to know that there will be impacts; and we know the nature of those impacts will be complex and depend on many factors.

Meanwhile, we have many decisions to make—about oil and gas extraction, shipping traffic and wildlife management to name a few. The pressure to make these kinds of decisions is increasing and the bottom line is that we don’t yet have a lot of good solid information with which to make them. Are we even prepared to make these decisions at all based on the information at hand? While the race for better scientific understanding continues, perhaps the biggest question in front of us is just what kind of decisions we are willing to make in the face of so many uncertainties.

For a more detailed discussion of the study click here.

To read the study (behind a paywall), here’s the study:
Hjorth, M. & Nielsen, T. G. (2011). Oil exposure in a warmer Arctic: Potential impacts on key zooplankton species. Marine Biology

Url: http://dx.doi.org/10.1007/s00227-011-1653-3
Doi: 10.1007/s00227-011-1653-

Calaunus glacialis image: http://www.arcodiv.org/

Copepods begin to increase in number following the proliferation of algae as the summer ice begins to recede. Image: Eric Solomon.

Thick billed murres eat both copepods and the fish that feed on them. Image: Eric Solomon.

Mother and cub await the ice so they can hunt seals that feed on the fish that feed on the copepods that feed on the algae that get their energy from the sun. Image: Eric Solomon.

 

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