Scientists Discover Potentially New Algae Species in the Kuril Islands

Seaweed communities on Kunashir Island are undergoing a structural shift driven by rising ocean temperatures. During an expedition from September 6 to 15, phycologists from Vladivostok surveyed the littoral and upper sublittoral zones—down to a depth of two meters—finding that shifting thermal regimes are altering the region's floral composition.

Photo: Wikimedia Commons by Melina Marcou, https://creativecommons.org/public-domain/pdm/

Posidonia oceanica

The transformation is propelled by the Tsushima Current and its Soya branch, which transport warm waters and southern species toward the Okhotsk coasts of Kunashir and Iturup. This process operates through two simultaneous vectors: the expansion of thermophilic southern algae and the degradation of cold-water species. The decline of cold-adapted flora is already evident in the reduced biomass of brown laminarians on Moneron and the Commander Islands.

The loss of laminarian forests, such as the Japanese Saccharina, removes the primary physical architecture of the seabed. These forests serve as critical shelters and feeding grounds for hundreds of marine organisms; their disappearance threatens the overall biological productivity of the Sea of Okhotsk.

Anna Skriptsova (NNCMB FEB RAS) and Maxim Astakhov (Federal Research Center for Biodiversity FEB RAS) conducted sampling across the Pacific coast—from the Ilyushin River to the Rubezhny stream and Devil's Finger rock—and the Okhotsk coast between Stolbchaty and Krugly capes. By combining traditional herbarium collection with molecular genetic analysis, the team identified "cryptic species"—organisms that appear identical physically but differ genetically.

This genetic evidence refutes previous classifications that grouped Kuril species with Atlantic counterparts, proving instead that they belong to distinct genera endemic to the Pacific. The researchers also detected preliminary evidence of the genus Callophyllis, which may include species new to science.

Beyond ecological monitoring, the expedition assessed the region's resource potential. Red algae, specifically Porphyra and Gigartina, are of particular interest due to their carrageenan content. These polysaccharides are used as stabilizers in pharmaceutical applications and food production, including dairy products and sauces.