Comparison of four measuring techniques to assess growth inhibition in standardized tests with seven freshwater algae and cyanobacteria

ABSTRACT

As representatives of primary producers, algae and cyanobacteria play an important role in assessing the risk of chemicals. However, the list of standard algal species commonly used for toxicity testing comprises very few species so that there is an urgent demand to identify further non-standard species which can be used for higher-tier risk assessment in general and the analysis of species sensitivity distributions in particular. In this study, four measuring techniques to assess growth inhibition were compared using five non-standard and two standard algal species and 3,5-dichlorophenol as reference substance. Regarding sensitivity and suitability, the measuring techniques were ranked in the following descending order: delayed fluorescence, prompt fluorescence, photometric absorbance, and microscopic cell count. All five non-standard species fulfilled the validity criteria if tested with delayed fluorescence.

KEYWORDS:

• Delayed fluorescence
• prompt fluorescence
• non-standard algal species
• 3,5-dichlorophenol

Acknowledgments

The present study was financially supported by the Neu-Ulrichstein (FNU) Research Center and Bik-F and funded by the Landes-Offensive zur Entwicklung Wissenschaftlich-ökonomischer Exzellenz (LOEWE) program of Hesse's Ministry of Higher Education, Research, and the Arts. We are especially grateful to Prof. Dr Jörg Öhlman, for his help to improve the manuscript. The reviewers are also acknowledged for their helpful comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The Neu-Ulrichstein Research Center; Biodiversity and Climate Research Centre Frankfurt (BiK-F); Landes-Offensive zur Entwicklung Wissenschaftlich-ökonomischer Exzellenz (LOEWE) program of the Ministry of Higher Education, Research, and the Arts of the State of Hesse.