CEA presented 16 posters at SETAC Dublin in April/May 2023. We will be showcasing each of these presentations in a series of ‘SETAC Spotlight’ articles. This week it is:
Mesocosm Studies: Representativeness and Reliability
Authors: Marie Brown1, Ellie Welch1, Nadine Taylor1, Seamus Taylor2
1Cambridge Environmental Assessments; 2ADAMA Agricultural Solutions Ltd
In recent years, the representativity and reliability of mesocosm data for regulatory risk assessment has been challenged, with some research suggesting that the organism diversity and abundance found in mesocosms does not represent the same levels typically found in natural waterbodies. In addition, some mesocosm studies have been criticised for their low statistical power to detect treatment related effects.
We believe that mesocosm studies can provide a conservative, and protective, tool to evaluate the effects of pesticides to freshwater communities. To explore this representativity question further, we compared macroinvertebrate control data from a mesocosm study conducted at CEA to data collected over two years from natural water body types (ponds, ditches and streams) to demonstrate that data from mesocosm studies can be representative of natural waterbodies.
Although there were some differences in species collected, when grouped, the number of taxa and abundance of ecologically relevant and sensitive taxa were comparable between mesocosms and natural water bodies. The mesocosm data was mostly comparable with ditches in terms of overall relative abundance and overall number of taxa, and was mostly comparable with ponds in terms of Biological Monitoring Working Party (BMWP) and SPEcies At Risk of pesticides (SPEAR) scores, demonstrating that mesocosms are representative of these types of natural in-field and edge-of-field waterbodies.
The abundances of many taxa within the mesocosm study were consistently high enough to be statistically robust i.e. minimum detectable difference (MDD) Category 1.
This investigative work supports that mesocosms can represent communities that are sensitive to pesticides, meeting the EFSA (2013) Aquatic Guidance document requirements for the number of sensitive/vulnerable taxa with acceptable MDD values and thus reliable endpoints.
Overall, we believe mesocosms remain a valuable option in the risk assessment toolkit and that concerns over representativity and reliability are unwarranted.
The poster is available for free download.
You can find all of the other posters that CEA presented at SETAC Dublin here. You can also find all of our publications from previous conferences and links to journal articles we have authored on our library page.
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