A massive phytoplankton bloom has been found underneath of the Arctic pack ice in the Chukchi Sea. The “impossible” discovery will require a completely new understanding of Arctic ecosystems, and is a clear signal of the changing climate in the Arctic. The discovery was made during NASA’s 2011 ICESCAPE expedition.
To thrive, phytoplankton need light and nutrients. The Arctic is generally very rich in nutrients but is covered in thick ice during the winter. It had previously been believed that this was too thick, and blocked too much sunlight, for blooms to occur.
“The assumption in the Arctic is that nothing gets going until the ice melts … there’s just not enough light under the ice,” said Stanford environmental Earth system science Professor Kevin Arrigo.
But, during the ICESCAPE expedition last year, the researchers found a phytoplankton bloom extending more than 30 meters deep and more than a hundred kilometers across, underneath the ice.
The researchers think that it’s possible that blooms like this are common across the nutrient-rich Arctic continental shelf. There are questions about how long these have been going on though. Are they caused primarily by recently thinning sea ice and an increased numbers of meltwater ponds? Or have they been occurring for a longer time?
The discovery means that there is likely vastly more biological activity occurring in the Arctic than previously estimated. This could mean that the Arctic is capable of storing much more carbon than previously estimated.
The magnitude of the bloom is what the researchers say they were most surprised by. “There are very few places anywhere in the ocean that such a bloom is observed,” Walker Smith, a biological oceanographer at the Virginia Institute of Marine Science in Gloucester Point said. “It’s very surprising, both in location and magnitude.”
So far, the implications for the food web are unclear, but the earlier blooms may not be good news for migratory animals like gray whales.
“The blooms are happening possibly weeks before the ice begins to retreat,” Arrigo says. Timing, he notes, is a really important issue in the Arctic, with its short seasons. “We have no idea how this might be changing those [migratory] patterns.”
“It’s entirely possible that it would be a disaster, and entirely possible they could adapt to this change fairly easily—most likely it’s in between. The fauna tends to be smarter than we give them [sic] credit for, in terms of adaptations and acclimations which they undergo in response to changing environment.”
Image Credits: NASA/Kathryn Hansen