The prevalence and acceptability of mesocosm studies submitted for macrophytes in pesticide risk assessment

Navarro Law, Isabel, Brown, Colin D., Snape, Jason, Durance, Isabelle ORCID: https://orcid.org/0000-0002-4138-3349, Reed, Melissa and Fryer, Michael 2025. The prevalence and acceptability of mesocosm studies submitted for macrophytes in pesticide risk assessment. Integrated Environmental Assessment and Management , vjaf164. 10.1093/inteam/vjaf164

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Abstract

Mesocosms can be used in higher tier aquatic risk assessments to assess the impact of Plant Protection Products (PPPs) on macrophytes. However, it is unclear whether these expensive and time consuming higher tier studies influence regulatory outcomes. This review highlights common shortcomings in the experimental design of mesocosm studies, with the aim of maximising the regulatory value of future mesocosm studies. Fourteen mesocosm studies, which have been submitted for the regulatory risk assessments for macrophytes in the EU or GB, were identified and reviewed. Results show that only five of the 14 mesocosm studies were deemed acceptable by the regulatory authorities, suggesting that mesocosm studies are not currently being used to their full potential. Issues with the submitted studies include not following a realistic PPP exposure profile (including incorrect dose timings and dilutions), only using one macrophyte morphology, not leaving enough time for the macrophytes to establish and a lack of replicates which increases variability within treatments. Glyceria maxima and Myriophyllum spicatum were frequently the most sensitive macrophyte species, whilst dry weight was often the most sensitive and least variable endpoint. Even though mesocosms provide the opportunity for recovery and community responses to be observed, such information has not been used by regulatory authorities. Future regulatory mesocosm studies can build upon the shortcomings highlighted here, providing a greater chance of regulatory impact.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Biosciences Research Institutes & Centres > Water Research Institute (WATER)
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2025-11-10
Publisher:	Oxford University Press
ISSN:	1551-3777
Date of First Compliant Deposit:	25 November 2025
Date of Acceptance:	22 October 2025
Last Modified:	25 Nov 2025 11:15
URI:	https://orca.cardiff.ac.uk/id/eprint/182628

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