Cyanobacteria in the water, a nightmare of Polish bathing waters

Cyanobacteria in the water, a nightmare of Polish bathing waters

Most of you will probably be familiar with holiday headlines such as 'bathing ban - blue-green algae bloom' etc. In the material below I explain what cyanobacteria are, what the term "cyanobacterial bloom" means and where the swimming ban in reservoirs with cyanobacteria comes from.

Cyanobacteria - what is it?

Cyanobacteria are aquatic microorganisms commonly found in surface waters (fresh and salt). Like plants, they need sunlight to live. Under normal conditions, cyanobacteria are too small to be visible to the naked eye.

Under conditions of increased presence of nutrients (mainly nitrogen and phosphorus) in the water and favourable water and air temperatures (summer period), a so-called cyanobacterial bloom occurs. A cyanobacterial bloom is a rapid growth of these micro-organisms causing the formation of floating blobs on the water surface that are visible to the naked eye.

This is a disadvantageous phenomenon not only visually, as the blue-green algae bloom also causes:

  • blocking sunlight
  • excessive consumption of nutrients
  • reduced oxygen availability

All this generates nutritional deficiencies for other aquatic organisms, often causing their death.

Cyanobacteria in water - a danger to humans

Cyanobacteria in water produce toxins that can be very dangerous for humans. Bathing in a body of water with blue-green algae can result in:

  • skin lesions,
  • food poisoning,
  • neurological disorders.

In critical cases, such bathing can result in death!

Not surprisingly, the presence of cyanobacteria in bathing areas is unacceptable and regulated. The Ministry of Health's Bathing Water Regulation states that bathing water should not contain "...cyanobacterial blooms taking the form of dross, streaks or foam...". [1]. Hence, if a cyanobacterial bloom has occurred at a particular bathing water site, bathing should be strictly prohibited.

Anabaena sp.
Anabaena sp
Oscillatoria sp.
Oscillatoria sp.

Cyanobacteria testing

Identification of cyanobacteria can be difficult due to their microscopic size. In addition, there may be algae in the reservoir that will be mistakenly identified as cyanobacteria. Therefore, in the framework of cyanobacteria surveys, organoleptic assessment alone is not sufficient.

Cyanobacteria - microscopic examination

Reliable determination of the presence of cyanobacteria in water, as well as their classification into a particular species, requires microscopic observations in the laboratory. This makes it possible to detect cyanobacteria even before their bloom or to exclude their presence. Such microscopic examination of cyanobacteria will be performed at the SGS Poland Environmental Laboratory in Pszczyna.

Agnieszka Rybarska, SGS Poland expert in Industries & Environment

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