Aquatic outdoor mesocosm studies

gaiac conducts aquatic outdoor mesocosm studies under GLP conditions (Good Laboratory Practice) for the purpose of plant protection product registration. In 2003, a new field mesocosm facility has been constructed according to the state of the art under consideration of the actual guidance documents and regulations. In this system, the impact of pesticides and other chemicals on complex communities of lentic waters can be investigated under outdoor conditions. This test facility consists of 31 ponds (mesocosms) with a volume of 5 m3 each, and a central mixing pond. Thus, it is possible to conduct two independent mesocosm studies at the same time with varying numbers of ponds per each study. The studies are offered in cooperation with the Fraunhofer IME, Schmallenberg and other partners under GLP.

Aquatic Mesocosm studies

In addition, gaiac offers the determination of biological samples and the statistical analysis and reporting of externally performed mesocosm studies. Also for the re-evaluation of older studies in the light of the new EFSA Guidance Document (2013), we perform the required statistical calculations and evaluations (e.g. as published in Brock et al. 2015).


Brock T.C.M., Hammers-Wirtz M., Hommen U., Preuss T.G., Ratte H.-T., Roessink I., Strauss T., Van den Brink P.J. (2015): The minimum detectable difference (MDD) and the interpretation of treatment-related effects of pesticides in experimental ecosystems. Environmental Science and Pollution Research 22:1160-1174. DOI 10.1007/s11356-014-3398-2. (open access with supplementary material).


The research group of Prof. Dr. Hans Toni Ratte at the Institute for Environmental Research (1998-2002) and gaiac (since 2003) have performed a total of 20 confidential studies in aquatic outdoor mesocosms and four microcosm studies studies with the following groups of active ingredients: insecticides (12), fungicides (5), herbicides (6), biocides (1).

Taxonomic groups

Phytoplankton, periphyton, macrophytes, zooplankton, macroinvertebrates (several habitats), emerging insects

Additional investigations

In situ-bioassays with Lemna minor and several macrophytes in aquatic mesocosm studies (e.g. Myriophyllum spicatum, Potamogeton lucens, Elodea canadensis, Glyceria maxima, Sparganium erectum, Ceratophyllum demersum and Chara globularis) as well as with invertebrates such as Asellus aquaticus and Gammarus pulex.


Strauss T, Hammers-Wirtz, Hommen U, Norman S (2013): Optimizing experimental setup and sampling techniques to assess pesticide effects on macroinvertebrates in aquatic mesocosm studies. 23th SETAC- Europe Annual Meeting 12-16 May 2013, Glasgow, Scotland.

Hammers-Wirtz M, Strauss T (2010): The use of the minimum detectable difference (MDD) can improve the assessment of effects in community studies. Poster presentation, 20th SETAC- Europe Annual Meeting 23-27 May 2010, Seville, Spain.

Hammers-Wirtz M, Strauss T, Ratte HT (2007): Aquatic mesocosm studies as a tool in higher-tier risk assessment for pesticides - Variability in zooplankton populations, Platform presentation, SETAC Europe 17th Annual Meeting, 20.-24. Mai 2007, Porto, Portugal.

Your contact:

Dr. Tido Strauss
Dr. Monika Hammers-Wirtz

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