Battle against invasive algae continues in Yyteri as eutrophication threatens rare dunes

Eutrophication in the Baltic Sea has brought large amounts of foul-smelling algae to the shores of Yyteri in Pori, accelerating the spread of common reed that displaces the protective vegetation of the fragile sand dunes, reports Finnish broadcaster Yle.

Visitors to Yyteri may encounter piles of brown, malodorous algae along the shoreline. The nutrient-rich algae create ideal growing conditions for invasive reed plants, which threaten to overrun the unique dune ecosystem. While cleanup efforts are underway, experts warn the battle cannot be won as long as excess nutrients continue flowing into the sea.

Anne Salo, Pori’s nature conservation supervisor, explains that agricultural fertilizers and drainage from peatlands and forests contribute to the nutrient overload. “Algae blooms thrive due to eutrophication, and ocean currents eventually wash them ashore,” Salo says.

The dunes, naturally a harsh environment with specialized vegetation, face an existential threat. Without intervention, Salo estimates the dunes could disappear entirely within years. Currently, the main bathing beach remains unaffected as currents push most algae toward the northern edge of the area, but the situation is concerning. Climate change further exacerbates eutrophication as temperatures rise.

Efforts to mitigate the problem include mechanical removal of algae and mowing reed growth. “It’s crucial to eliminate the nutrients completely—algae and reed waste must not be left in piles here,” Salo emphasizes. However, she acknowledges that while the impacts can be slowed, a full reversal is impossible. “We can’t stop or reverse the process entirely. The ecosystem won’t return to its barren state because nutrients keep entering from the sea.”