A Rapid Bioassay Using the Green Alga to Screen for Toxicity in St. Lawrence River Sediment Elutriates
SourceA toxicity bioassay using the green alga Selenastrum capricornutum and measuring inhibition of photosynthetic carbon-14 (14C)-labeled carbon dioxide (14CO2) assimilation is described. The essential test specifications are the following:
(a) experimental vessels: 16-mL test tubes;
(b) exposure and incubation times: 20 h exposure plus 4 h incubation;
(c) dilution water: demineralized H2O;
(d) algal cell density: 1.9 × 105 cells mL−1;
(e) radioactivity: 0.072 µCi mL−1, as 14C-labeled sodium bicarbonate [Na2(H14CO3)2];
(f) nutrient enrichment: 1 mL of × 10 provisional algal assay procedure (PAAP) medium; and
(g) isotope partitioning: acidification and bubbling.
The resulting method is rapid, sensitive, and reliable (coefficient of variation < 10%) and is applied to elutriates of St. Lawrence River sediments in an ongoing research project.