Prymnesium parvum plagues the US southwest

24 August 2011

Prymnesium parvum

The tiny Chrysophyte, Prymnesium pavum, is plaguing lakes suffering from drought in the US south-west.  Prymnesium is a highly-specialized alga belonging to a group known as the golden algae.  Prymnesium proliferates under very specific, sometimes highly-variable, conditions of physico-chemical stress in lakes – typically slightly-elevated salinity and nutrient stress that precludes ‘desirable’ algae from competing.  It also produces compounds that are toxic to fish, resulting in massive fish kills.

Haptophytes are important in the aquaculture industry – but not Prymnesium or Chrysochromulina – which form icthyotoxic blooms.

I am aware of two fish kills caused by Prymnesium in South Africa, both in Cape Town. The first was back in the 1970s in Zandvlei, the second a couple of years ago in Rietvlei (although it was completely missed by those investigating the case).  Because it is so small and hard to see, it is often missed by inexperienced microscopists.

I am pleased to part of a group seeking an immediate relief solution for this problem!

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