Along the Finnish coast, within the Gulf of Finland waters, local residents have spotted an unusual natural occurrence: in places, both the water and the ice near the shore have taken on hues of red and reddish-brown. This was particularly noticeable around Helsinki, as reported by DP.
According to the Finnish Environment Institute (Syke), there is no cause for alarm. The institution stressed that this alteration in the ice’s color is a routine and harmless occurrence.
Specialists attribute the peculiar tint to the brown algae species Fucus vesiculosus, which is widespread in the Baltic Sea coastal zone. When these algae decompose, they release a reddish pigment that the plant utilizes during photosynthesis. This very pigment is what imparts the characteristic coloration to the ice.
In the Baltic Sea, Fucus vesiculosus is considered the dominant species. It generates dense underwater thickets, extending from the water surface down to depths of about 10 meters. Syke indicated that a significant abundance of this algae, conversely, serves as a positive indicator of the marine environment’s health.
A comparable reddening of ice and snow has been observed in polar territories—the Arctic and Antarctic. In those regions, microscopic single-celled algae are the cause, which, upon mass proliferation, can also alter the color of the ice cover.
Experts made a specific point to remind the public that cyanobacteria (blue-green algae) pose a potential threat. During their bloom and subsequent decay, they have the capacity to release harmful toxins. Last summer, substantial accumulations of these algae were documented in the Gulf of Finland and the Archipelago Sea.
This winter, the Gulf of Finland froze over as far west as the Finnish coast—a similar extent of ice coverage was last seen in 2011. As of March 4th, the ice sheet persisted across approximately 70 percent of the sea area.
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