• Daphnia;
  • PUFA;
  • fatty acid;
  • lipid;
  • microcystin;
  • toxic;
  • harmful;
  • zooplankton;
  • phytoplankton


Polyunsaturated fatty acids (PUFAs) are essential components of zooplankton diets. However, studies with PUFAs from cyanobacteria indicate toxic properties. We investigated the toxicity of the PUFA γ-linolenic acid and the cyanobacterial peptide toxin microcystin-LR to Daphnia. The PUFA was acutely toxic at a concentration of 9 μg ml−1. The effect of microcystin-LR was not statistically significant at the concentration used (3 μg ml−1), but an additive effect with the PUFA was observed. Relative to LC50-values of well-known pollutants, the PUFA was intermediately toxic. The activity equaled that of microcystin-LR, which is commonly treated as one of the most potent cyanobacterial toxins. Our results suggest that the toxic properties of PUFAs deserve more attention. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 444–448, 2001