The use of a cellular fluorescence capacity (CFC) index as a toxicity
end point for the alga, Selenastrum copricornutum was examined. The in
dex is calculated from algal fluorescence before (F) and after (F-d) t
he addition of the herbicide 3(3,4-dichlorophenyl)-1,1-dimethyl urea (
DCMU) and is expressed as a proportion [(F-d-F)/F-d]. CFC was compared
to algal growth response in 96-hours in bioassays with copper, zinc,
pentachlorophenol, a complex mixture obtained from a sewage treatment
works effluent and four sediment pore water samples. Although not alwa
ys as sensitive as the 96-hour growth response, CFC was usually more s
ensitive than the 24-hour growth response and was able to detect the t
oxicity of copper to the alga species as early as 5 hours. CFC was a u
seful endpoint in toxicity determinations and demonstrated potential a
s a rapid short term screening response for toxicity. (C) 1997 Elsevie
r Science Ltd.