Nontarget effects of carbaryl and its hydrolysis product, 1-naphthol, towards Anabaena torulosa.

The toxic effects of carbaryl and its hydrolysis product, 1-naphthol, singly and in combination, towards a filamentous diazotrophic cyanobacterium, Anabaena torulosa, were determined. The toxicity criteria employed, viz., packed cell volume, chlorophyll a, phycocyanin, carotenoids, heterocyst differentiation and nitrogen fixation, were greatly affected by the toxicants above 25 micrograms/ml concentrations. However, 1-naphthol was more toxic to the diazotroph than was carbaryl. The toxicity was more pronounced when carbaryl and 1-naphthol were in combinations even at lower concentrations.