Algal bloom
Sweden:
When different species of algae start to grow very fast and makes big populations.
Often close to the surface because of the sun and during calm weather. Not bound to season or time of the year, but are mostly harmful from late summer to the beginning of the autumn.
Happens naturally but over-fertilization causes much phosphorus and nitrogen.
Looks like a green-yellow or blue-greenish layer on the surface.
Not dangerous to bathe in but shouldn’ t be swallowed. It might cause irritations or, in big quantities, be poisonous for humans or animals. Some algae can be found in clams which are eaten by humans.
Cyanobacteria is, a little misleading, a type of algae which are ordinary in the Baltic Sea.
Belgium:
In the North Sea there are hundred thousand to hundred million plankton algae per liter of sea water.
Every year around spring, when the days get longer, millions of microscopic weeds develop in the sea. They use the nutrients( nitrates and phosphates) that are present in the water for their growth. If our rivers dispose to many of these nutrients in the sea, there will be an overgrowth of algae.
The consequences of algae bloom are diverse: Oxygen deficiency in the water Changes in the ecosystem
Development of algae species that produce toxins that can be harmful to humans and animals
Deterioration of water quality( bad smell and taste), the water becomes brown à sometimes impossible for divers to see something
The algae growth that occurs in spring in front of are cost is visible through the foam flakes( img. 1) that form when remains of foam algae( scientific name: Phaeocystis) get whipt it by the waves.
Phaeocystis are single cell algae’ s( img. 2) their measurements vary between 3 and 7 µ m in diameter. Around spring, especially on the windy days, a lot of the times the beach is covered with large amounts of foam, sometimes these piles can become over 50cm tall. A lot of people have questions about this matter. What is this? Where does it come from? Is it pollution, or harmful?
The Algae on our cost mainly consist of one kind Phaeocystis pouchetti, these are very slimy. there are two possibilities, either they come as a single cell, which is not visible to the human eye, or they come in groups, which is visible to the human eye. These groups of algae are covered in some kind of gelatine. If the algae die, a lot of gelatine comes free and then the waves clutch it up to a big pile of foam.
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