Significant trends toward earlier phytoplankton blooms (blue) were detected in about 11 percent of the area of the Arctic Ocean closest to the North Pole, delayed blooms (red) were evident to the south. Credit: Scripps Institution of Oceanography, UC San Diego

By Michael Ricciardi
March 3, 2011 Over the past decade, the Arctic’s annual “bloom” of phytoplankton has been arriving earlier each year. The trend in earlier blooms of this crucial,  primary producer of the Arctic’s food web is occurring largely along coastal and ice edge areas within the Arctic circle, with the exception of large patches in the northern Pacific Ocean. A recent survey by a team of oceanographers from the Scripps Institution of Oceanography (UC San Diego), Mexico and Portugal, found evidence of earlier algal blooms in roughly 11 percent of the area ringing the Arctic Ocean, and closest to the North Pole. Delayed blooms were found more commonly in southerly regions around the Arctic (note: algal blooms can occur in both warmer and colder waters, but the composition of the plankton community will vary). Using satellite imaging data depicting ocean color and phytoplankton production, the scientists found that in some areas around the Arctic, peak blooms have been arriving up to 50 days earlier over this ten year period. The problem, of course, is that large numbers of fish depend, directly or indirectly, on phytoplankton. The greatest increase in the fish population is tied to the peak plankton numbers of these one to two week bloom periods. If, however, many of these plankton blooms are trending earlier each year, then the seasonal return/growth of  the fish population in these areas is gradually becoming “out of sync” with the primary producers in this region. This may mean insufficient food supply to maintain robust fish populations. …

Arctic Plankton Blooms Arriving Earlier, Fish May Be Imperiled