Combined Algae Test with Unicellular Green Algae

Test organism

• Unicellular freshwater green algae (Raphidocelis subcapitata)

Detectable effects (impact)

• Inhibition of photosynthesis (herbicidal effect)
• Inhibition of growth

Test principle

• In this test, the herbicide-induced, specific effects of chemicals or environmental samples on the photosynthesis of algae after 2 h and 24 h exposure time are recorded and the unspecific effects on the growth of the algae after 24 h exposure time are measured.
• The test combines the assessment of photosynthesis and growth inhibition.
• Growth inhibition stands for unspecific toxicity and is determined by means of the cell density through absorption at 685 nm.
• Photosynthesis inhibition is based on the inhibition of Photosystem II (PSII) and indicates herbicide-specific toxicity.

Test procedure

• Download flow chart combined algae test
• SOP available on request from Andrea Schifferli

Video tutorial

Test duration

• 24 h

Relevance

• Substitute organism for primary producers
• Standard test organism for water quality evaluation (OECD, US EPA, ISO)

Guidelines and literature

• Escher BI, Bramaz N, Mueller JF, Quayle P, Rutishauser S (2008). Toxic equivalent concentrations (TEQs) for baseline toxicity and specific modes of action as a tool to improve evaluation of ecotoxicity tests on environmental samples J. Environ. Monit. 10, 612-621.
• Escher BI, Rutishauser S (2007). The combined algae test- a new routine 96-well-plate biotest for simultaneously assessing the photosynthesis inhibition and effect on growth in green algae. Internal Report, Eawag, Dübendorf, Switzerland
• International Organization for Standardization (2004). Water quality -- Freshwater algal growth inhibition test with unicellular green algae. ISO 8692: 15 p.
• Schreiber U, Quayle P, Schmidt S, Escher BI, Mueller J (2007). Methodology and evaluation of a highly sensitive algae toxicity test based on multiwell chlorophyll fluorescence imaging. Biosens. Bioelectron. 22, 2554-2563.