As Sweden basks in a heatwave, algal blooms in the Baltic Sea are threatening summer swims, particularly around Gotland. With temperatures soaring above 30 degrees, SMHI advises caution, urging people to stay hydrated and cool. Algal blooms, thriving in the warm, calm waters, pose a risk if ingested, especially for children and pets. Symptoms like nausea and diarrhea may occur if large amounts are swallowed. Follow safety tips to enjoy the water safely.
Algal Bloom Threatens Sweden's Summer Swims: Safety Tips Inside
Algal Bloom Threatens Sweden's Summer Swims: Safety Tips Inside
The heatwave is gripping almost the entire country. Meanwhile, algal blooms in the Baltic Sea have surged, encircling Gotland. Now, refreshing summer swims are at risk in several locations.
In the coming days, SMHI warns of significant heat. All of Sweden is under a high-temperature alert for the weekend. The heat will persist in the central and northern parts of the country on Monday and Tuesday.
In many areas, temperatures are expected to reach, or even exceed, 30 degrees.
"Drink water and take it easy. Monitor indoor temperatures and find ways to cool down," SMHI advises the Swedish public.
When Algae Bloom
But it's not just vacationers enjoying the midsummer weather right now—bacteria in the sea are too.
"Conditions are favorable for algal bacteria now—this leads to algal blooms in the water," says Simon Pliscovaz, an oceanographer at SMHI.
Since it was windy in June, the water was mixed in many places, preventing algae from growing and gathering, he explains.
But now in July, the heat has risen while the wind has calmed, causing the algal bloom to accelerate. Virtually all of Gotland is surrounded by blooming algae.
"When the sun shines, algae get the light they need, and if there are nutrients in the water, they multiply and grow. If it's also warm outside, a warm surface layer forms where algae gather."
Where It's Worst
Such a layer of murky algae at the sea surface currently forms a thick band along eastern Sweden from Blekinge to the archipelago south of Stockholm, according to SMHI's algae report for Saturday. The entire Gotland is also surrounded by blooming algae.
The exception is Kalmarsund, where it looks clearer.
Along the Norrland coast, the West Coast, and around Skåne, it is mostly free from algal blooms for now.
And that's roughly how it looks set to continue, believes Simon Pliscovaz, as it doesn't seem to be particularly windy anywhere in Sweden in the coming days.
"As long as the sun is out and it's not very windy, the algae will likely remain where they are."
Want to Swim Anyway? Keep an Eye on This
Although it may seem unpleasant, it's not dangerous to swim in water with algal blooms—if you don't ingest large amounts of water with bacteria, says Simon Pliscovaz.
"You shouldn't swallow the water, and it might also be smart to rinse off afterward to avoid skin problems."
But with children and animals dipping in the water, one should be extra vigilant, he thinks.
"They can't control their gulps. If you want to avoid children and animals ingesting algal blooms, keep an eye on them at the beach."
Can Lead to Diarrhea and Vomiting
If you do ingest large amounts of algal water, be aware of a few symptoms. If you experience nausea, diarrhea, and vomiting, you should see a doctor, says Simon Pliscovaz.
"But usually, it takes quite a bit of water to get sick. If you follow the advice and use some common sense, you should be able to swim and cool off without major problems."