Järviwiki:Ohje/Näin teet havainnot/Sinilevätilanne/en

Assessing the blue-green algae situation is one of the easiest observations anyone can make. Blue-green algae detection is done visually and does not require tools. The observation "No cyanobacteria" is also important and worth reporting.

Identification of cyanobacteria

Minor cyanobacteria appear in the water as small yellowish or greenish pollen-like peaks. In calm weather cyanobacteria form a gauze-like greenish film on the surface of the water.

Pollen seems misleadingly similar to cyanobacteria. However, pollen is especially present in water in spring and early summer, but cyanobacteria usually only become abundant after mid-summer when the waters warm up. If there is a lot of pollen in the water, it is usually also abundant on the beach.

The glass test and the stick test are good tools for identifying cyanobacteria.

The glass test

Take algae water in a glass or glass jar and let it stand for about an hour without moving. If green particles rise to the surface, it is blue-green algae.

The stick test

Test with a stick to see if the algae mass is solid and can be lifted. If the algae remains hanging on a stick, it is a harmless filamentous algae. Blue-green algae, on the other hand, decomposes on contact into particles in water.

Estimation of cyanobacterial abundance

The abundance of algae is assessed visually on a four-point scale.

No blue-green algae	No cyanobacteria are detectable on the water surface or in shallow water near the shore. Depth of view is normal.
Some blue-green algae	Blue-green algae can be seen as greenish flakes or sticks in the water. Algae is visible if water is taken into a transparent container. Narrow stripes of algae may have drifted onto the beach. Algae impairs depth of vision.
Abundant with blue-green algae	The water is clearly rich in algae, or small algal rafts have risen to the surface or algae deposits have drifted onto the beach.
Very abundant with blue-green algae	Algae form extensive algal rafts or have drifted ashore into thick piles.

Some blue-green algea

Abundant with blue-green algae

Very abundant with blue-green algae