On July 16, 2025, the waters of the Avacha Bay in Kamchatka turned a rich purple-red color, which became a visual manifestation of the so-called “red tide”. The cause of the phenomenon was the explosive proliferation of toxic microalgae of the Alexandrium tamarense species, which produce saxitoxin, a deadly nerve agent.
The rapid proliferation of these microscopic organisms poses a direct threat to the entire marine ecosystem, leading to the mass death of fish, seabirds and mammals. Saxitoxin has the property of accumulating in the tissues of marine life that feed on it. Especially dangerous in this regard are bivalves, such as mussels and scallops, which filter the water and concentrate the poison in themselves, becoming a deadly trap for humans.
The alarm was sounded by scientists of the Kamchatka branch of the Pacific Institute of Geography of the Far Eastern Branch of the Russian Academy of Sciences. As early as July 15, the concentration of dangerous cells in water samples near Cape Signalny was 136 thousand per liter, which was already a cause for concern. However, the situation deteriorated catastrophically in just one day: on July 16, 3 million 272 thousand cells per liter were recorded at the same cape Signalny, and in Mokhovaya Bay the figure reached a record 5 million 727 thousand cells. The forecasts are disappointing: against the background of warming water, scientists expect further, even more intensive growth in the number of toxic algae.
The current event raises serious concerns in light of the tragic events of the past. The history of Kamchatka remembers what the “red tides” lead to. In 1973, a mass poisoning of people with mussels caught during the algal bloom occurred in Petropavlovsk-Kamchatsky. Then 12 people were injured, two of whom died. Similar incidents have happened before, for example, in 1945, sailors of a fishing vessel died from eating poisonous mussels.
Due to the extreme danger, experts strongly recommend that the population and guests of the peninsula completely abandon the consumption of any seafood caught or harvested in Avacha Bay. The collection of mussels and other shellfish is strictly prohibited. In addition, swimming in coastal waters is not recommended until the situation normalizes, as contact with high concentrations of toxins can cause allergic reactions and other health problems. All information about the current situation and the necessary precautions has been sent to the regional Department of the Ministry of Emergency Situations for emergency notification of residents and guests of Kamchatka.
Currently, researchers continue to continuously monitor the dynamics of flowering, tracking the spread of the poisonous spot and assessing its devastating effect on marine life. Not only the ecological well-being of one of Kamchatka’s key bays, but also the safety of thousands of people will depend on the further development of the situation.