Arctic ice melt brings extra phytoplankton blooms

Phytoplankton bloom in the Barents Sea on August 3, 2014.

A new study reveals an unexpected consequence of the Arctic ice loss: regions are now developing a second bloom of phytoplankton in the fall in addition to the usual springtime bloom.


A study, led by scientists at Canada’s Laval University and published online in the journal Geophysical Research letters, describes the autumn blooms of phytoplankton that have become more frequent in the past 15 years. They occur late in the fall, just before the ocean freezes up.

Recent receding of the ice pack allows more sunlight to penetrate into the Arctic Ocean and waters to stay open longer than in the past. The twice-a-year blooms are happening in waters up to 73 degrees latitude in the western Arctic and even farther north than that in the eastern Arctic, according to the findings.

Because phytoplankton are the base of the marine food chain, places were blooms are large and frequent often support a thriving marine population. This is certainly the case in the Barents Sea where the fisheries, particularly the cod fisheries, are of great importance for both Norway and Russia.

The Arctic Ocean seems to be experiencing a fundamental shift from a polar to a temperate mode, which is likely to alter the marine ecosystem. Fish and marine mammals swimming in the upper layers of the water might benefit from the increased carbon coming into the bottom of the food chain, but the benthic ecosystem at the bottom of the sea and the ecosystem connected to the ice might suffer, lead author Mathieu Ardyna says to Alaska Dispatch News.

The spring blooms in the Arctic Ocean, long known to occur regularly, remain the primary blooms, according to the paper. Future research will focus on comparing the spring and autumn blooms and investigation of any potential links between them, the mechanisms behind the new fall blooms and the reasons why they occur in some places but not others

Expeditions to the Arctic in 2010 and 2011 revealed unprecedented blooms of ocean plant life beneath the ice, a discovery scientists compared to “finding a rainforest in the middle of a desert”, as BarentsObserver reported.