Each spring, rising temperatures and melting ice triggers the phytoplankton – tiny marine plants that form the base of the oceanic food chain – in the Arctic Ocean to proliferate, creating a one- to two-week bloom. The bloom stimulates the production of zooplankton, which provide food for fish.

In a study published in Global Change Biology, an international team led by Mati Kahru of the Scripps Institution of Oceanography at the University of California, San Diego used satellite data from 1997–2010 to map the annual spring bloom.

They found that the peak of the bloom has been getting progressively earlier over the study period. The earlier blooms were taking place in areas where ice concentrations had dwindled and created gaps.

The researchers warn that the advancement in the timing of the bloom could have significant impacts on both the marine food chain and carbon cycling in the region. ‘The spring bloom provides a major source of food for zooplankton, fish and bottom-dwelling animals,’ Kahru said. ‘The advancement of the bloom time may have consequences for the Arctic ecosystem.’

In particular, they are concerned about the possibility that the consumers of phytoplankton may be unable to match the earlier blooms and avoid disruptions of critical life-cycle stages such as egg hatching and larval development.

April 2011