A blue-hued visitor landed at the Naantali housing fair area – the armoured helmet is mainly a nuisance during swimming trips

Armoured hammerhead seabream has been present in the Baltic Sea for a long time, most extensively in Åland waters. Now it can also be found in small quantities on the shore of last summer’s housing fair in Naantali.

In recent years, the use of armoured honeysuckle has become more common in the Baltic Sea.

Also known as the sea fire and water spray, the armour seaweed is familiar to many because it creates a blue glow in the water.

Naantali housing fair area.
The Naantali housing fair area is near Matalahti.

Sjöqvist has visited the Matalahde area in front of the Naantali Housing Fairgrounds, and according to the researcher, the Alexandrium ostenfeldii species of the armoured hornwort has been present there for a few years. However, the algae are relatively scarce in the water.

According to Sjöqvist’s assessment, the armored flagella has become more common in Finnish waters in recent years.

The most abundant deposits have been found in the waters of Föglö in Åland. According to Sjöqvist, the species needs more research.

researcher Conny Sjöqvist in the grounds of the University of Turku
According to researcher Conny Sjöqvist, armoured horseshoe crabs have become more common in the Baltic Sea in recent years.

Poison does not pass easily to humans

Armor flagella is a single-celled microalgae that blooms in warm summer around August. Flowering does not happen every year.

The algae poison is transferred to the mussels and further forward in the food cycle.

– The poison transfers to the fish, but there is no evidence that it transfers to the fish’s flesh, states Conny Sjöqvist.

It is therefore very unlikely that algal poison would enter humans through food, as mussels from domestic waters are not used as human food here.

Armor flagella in brown water.
In the daytime, an armour plate might look like this.

Common sense for swimming trips

If you see armored flagella in the water, you should skip swimming.

– You should use common sense. After all, we avoid swimming if we see blue-green algae, Conny Sjöqvist says.

For some, flagella may cause symptoms on the skin.

Dogs should not be allowed in algae water, because they lick their wet fur and can get poison through it.