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Predicting and observing responses of algal communities to photosystem ii‐herbicide exposure using pollution‐induced community tolerance and species‐sensitivity distributions
Author(s) -
SchmittJansen Mechthild,
Altenburger Rolf
Publication year - 2005
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/03-647.1
Subject(s) - periphyton , atrazine , community structure , microcosm , ecotoxicology , biology , photosystem ii , ecology , environmental chemistry , algae , pesticide , photosynthesis , botany , chemistry
Various test strategies are in use in ecotoxicology to assess the potential risks of toxicants on aquatic communities. The species‐sensitivity distribution concept (SSD) works by arranging single‐species laboratory test data in a cumulative frequency distribution. The pollution‐induced community tolerance concept (PICT) uses observable community responses by measuring increases in community tolerance caused by the replacement of sensitive species after exposure. The aim of this study was to compare these two concepts in assessing the effects of three herbicides. Atrazine, prometryn, and isoproturon were found to increase community tolerance by a factor up to six. Atrazine increased community tolerance only at higher test concentrations (0.125 mg L −1 ). Species‐sensitivity distributions correspond well to community responses: The median effective concentrations (EC50s) of untreated periphyton communities tested covered 55 to 65% of affected species represented in the SSD. The sensitivities of tolerant algal communities shifted to the right end of the SSDs. In the microcosm experiments, higher test concentrations affected biomass, species numbers, and community structure. Community tolerance could not be induced any further, suggesting that these concentrations represent a maximum of functional redundancy of a functional group. At higher concentrations, even the least‐sensitive species are affected. These results can be interpreted as a confirmation of the SSD concept by observed algal community responses, when applied to photosystem II (PSII)—inhibiting herbicides.