INHIBITION OF CHLORELLA GROWTH BY DEGRADATION AND RELATED PRODUCTS OFLINOLEIC AND LINOLENIC ACIDS AND THE POSSIBLE SIGNIFICANCE OF POLYUNSATURATED FATTY-ACIDS IN PHYTOPLANKTON ECOLOGY

The activity of the degradation products of linoleic and Linolenic aci ds in inhibiting the growth of the green alga Chlorella pyrenoidosa wa s determined using the paper disk-agar plate method. Although hydroper oxides derived from these acids and aldehyde biodegradation products a nd other related aldehydes and alcohols showed inhibitory activity, it is concluded from the weakness of the activities that the inhibitory effects of polyunsaturated fatty acids (PUFAs) on Chlorella growth is due mainly to the acids themselves and not their degradation products. The evidence for the possible ecological role of PUFAs as toxic agent s against phytoplankton is presented.