Poisonous phytoplankton will change the future of the Arctic

(ORDO NEWS) — Scientists from the Greenland Institute for Natural Resources and the Center for Arctic Studies at Aarhus University tested the composition of seawater near the city of Daneborg in northeastern Greenland. They measured the concentration of phytoplankton in it, and noticed serious changes that could affect the future composition of the Arctic Ocean.

Plankton is a mass of small, often invisible plants and animals, which is the main food of many marine life. The part of plankton capable of photosynthesis is called “phytoplankton”, or planktonic algae. To survive, they need sunlight and access to nutrients dissolved in water.

It’s no secret that the area of ​​the Arctic glaciers is gradually decreasing. As it melts, the layer of ice in which the Arctic Ocean is chained becomes thinner, which improves the access of sunlight to its waters. Remarkably: the more light, the more phytoplankton, and therefore food for marine animals. Or is it not so simple?

Phytoplankton can multiply if there are enough nutrients in the water, light alone is not enough for it. These substances are found in seawater, and they are much less in fresh waters, which fill the ocean due to the melting of glaciers. Fresh water mixes poorly with sea water and remains on the surface, where phytoplankton concentrate in search of sunlight.

At the same time, there are mixotrophic organisms – they can both feed on other organisms and produce photosynthesis. Among planktonic algae, they are also common and the lack of light in water is easily replenished by eating their fellows in the microworld. In addition, mixotrophs reproduce more easily than others in a nutrient-poor environment.

All this makes mixotrophic plankton the most adapted to the changing conditions of life in the Arctic. However, earlier scientists did not notice blooming of this particular type of algae under the ice of the Arctic Ocean.

Researchers discovered this process during nine days of observing algal blooms under the melting ice of the Young Sund Fjord. The measurements took place in July, when there were more thawed patches in the Arctic ice off the coast of Greenland.

The algae found by scientists belonged to the group of haptophytes (Latin Haptophyta), which are poisonous. They were found in similar numbers earlier in the south of Norway, where they poisoned huge amounts of salmon on fish farms.

“We know that haptophytic algae can be observed in waters with low salinity, such as in the Baltic Sea, for example. It is possible that in the future they will increasingly appear in the waters of the Arctic Ocean due to their gradual desalination. This shift in concentration phytoplankton in favor of mixotrophic algae can have a profound impact on the ecology and socio-economic state of the region, “said Dorte H. Søgaard, lead author of the study.

Details of the scientific work are published in the journal Scientific Reports.

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