Chemosphere 2010-02-01

Proposing a pH stabilised nutrient medium for algal growth bioassays.

Rolf Altenburger, Janet Krüger, Adolf Eisenträger

Index: Chemosphere 78(7) , 864-70, (2010)

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Abstract

Ecotoxicological assessment of chemicals and contaminated sites relies on bioassays using apical endpoints such as detection of growth inhibition using suspension cultures of green algae. For valid effect assessment observable responses should be causally linked to chemical exposure and thus confounding factors should be minimised. In this study we report that concentration response relationships for substances in current standardised protocols for unicellular algal growth assays are prone to variation from ill-defined assay conditions. The currently used growth media are not optimised to provide a stable pH regime for an exposure period of 72h, resulting in undefined speciation for charged or ionising molecules. We therefore propose a modified pH-stabilised growth medium for algal bioassays and demonstrate that this can substantially reduce variation in effect determination for reference compounds.2009 Elsevier Ltd. All rights reserved.