Late Bloomers

Late Bloomers
Late Bloomers

Blooms of phytoplankton are common in the North Atlantic Ocean, but they don’t often last this long or reach this far north in September. The floating, microscopic plant-like organisms need sunlight and a source of nutrients to thrive, plus water at just the right temperature. Apparently they had all three in September 2019 near Newfoundland, Canada.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired these natural-color images of Newfoundland and surrounding waters on September 1 and 19, 2019. The brightest bloom appears southeast of the island, but fainter milky streaks are visible on nearly all sides. (The bloom was still visible through cloudy skies on September 22.) Note, too, the changing color of vegetation on land and the changing Sun angle as autumn set in.

According to marine biologist Cynthia McKenzie of Fisheries and Oceans Canada, countless coccolithophores of the species Emiliania huxleyi have been blooming offshore and blowing into harbors and bays around Newfoundland. The phytoplankton have chalky outer shells made of calcite, so they give the water a milky blue color when they aggregate in great numbers. Emiliania huxleyi cells are just 5 micron across—about 1,000 times smaller than a grain of sand—so their numbers have to be incredibly abundant to make a mass large enough for MODIS to detect. It helps that the calcite shells float for a few days even after the phytoplankton die.

According to Barney Balch of Bigelow Laboratory, blooms of Emiliania huxleyi “are commonly seen over the Grand Banks, but not at this time of year. Usually they occur closer to the summer solstice.”

“This is not our typical fall phytoplankton bloom, which would be made up of diatoms,” McKenzie said. She speculated that the late bloom is likely a result of “several weeks of sunlight—pretty rare for us in September—and higher than normal temperatures.”

Hurricane Dorian even passed through the area in early September, but the bloom has persisted. “I thought the hurricane would have had an effect, but if anything it seems to have fueled its continuation,” McKenzie added. “Most of the heavy wind was on the western part of Newfoundland, so what we had was some wave action which may have brought more nutrients to the bloom from further down in the water column.”

NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Michael Carlowicz.

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