FAQ

What is Prymnesium parvum?

Prymnesium parvum is a particularly adaptable microalgae that tolerates salinity levels of 0.5 PSU (in brackish water) to 30 PSU (in the sea) and grows at water temperatures between 2 and 30 °C. The algae has two flagella with which it swims and a holding organ, the so-called haptonema, with which it can cling to prey organisms. Prymnesium parvum owes its colloquial name "golden alga" to its two golden-yellow chloroplasts.

What makes the algae so dangerous?

The golden alga produces cytotoxins, the prymnesins. Under stress, the alga secretes these toxins and begins to capture and eat other organisms. The prymnesins destroy the gills of organisms living in the water and then enter their blood and internal organs, which they decompose. Fish die of respiratory distress and circulatory failure after the toxin destroys their red blood cells.

How does a mass bloom of Prymensium parvum occur? 

Under ideal conditions, such as increased salinity and sufficiently high levels of nitrogen and phosphorus, golden algae reproduce very quickly: it only takes a few days to double its biomass. It can reproduce in areas with calm currents, such as dams, but also in streams.

What don't we know about the algae yet?

Many questions about the algae and its toxicity have not yet been fully clarified. For example: What kills the organisms - the algae or the toxin in the water? Which genes of the algae are involved in the formation of its toxin? And: Does a permanent colonisation of the Oder with Prymnesium parvum threaten the restoration of the ecosystem? To answer questions like these, scientists at IGB are conducting research with other scientific partners in the special investigation programme ODER~SO.

How do we prevent another catastrophe?

The most sustainable measure is to reduce the salinity of the Oder, especially in the summer months.

More detailed information can be found in the IGB Fact Sheet "State of knowledge on the toxic alga Prymnesium parvum in the Oder River".