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The unusual timing of highly productive summer plankton blooms off Greenland indicates a connection between increasing amounts of meltwater and nutrients in these coastal waters. In a new study published today in the international journal Nature Communications, an international group of researchers led by the GEOMAR Helmholtz Centre for Ocean Research Kiel shows that this connection exists, but is much more complex than widely supposed. Whether increasing meltwater has a positive or negative effect on summertime phytoplankton depends on the depth at which a glacier sits in the ocean.
Observational data clearly shows that Greenland's mighty ice sheet is, slowly but surely, losing the race with rising global temperatures. Each summer, Greenland's glaciers transport more ice and meltwater to the ocean. There, among other things, the meltwater contributes to global sea-level rise. But does it also change the chemistry and biology of the oceans? According to a common theory, nutrients in the meltwater trigger plankton blooms off Greenland during the summer months.
Timing - Summer - Blooms - Plankton - Connection
"The timing of these summer blooms is actually unusual for plankton, so the connection with the meltwater seems obvious," says Dr. Mark Hopwood, chemical oceanographer at the GEOMAR Helmholtz Centre for Ocean Research Kiel.
However, Hopwood and colleagues from GEOMAR, as well as from the U.S., the Netherlands and Greenland, have found that this connection is more complex than previously thought. "Our samples and data show unambiguously that a retreat of glaciers inland will lead to a decrease in the extent of summer plankton blooms," says Dr. Hopwood. The team has published its results today in the international journal Nature Communications.
Factors - Amount - Meltwater - Plankton - Blooms
It was already clear that more factors than simply the amount of meltwater affect plankton blooms. "The main nutrient that plankton lack around Greenland is nitrate, while glacier meltwater contains mostly iron and silicon," explains Dr. Hopwood. The fact that the...
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