Effects of the fungicide pyrimethanil on biofilm and organic matter processing in outdoor lentic mesocosms
The effect of the fungicide pyrimethanil (0.7 mg L−1) on biofilm development and alder leaf litter decomposition in aquatic ecosystems was assessed in outdoor lentic mesocosms immediately and 274 days after pyrimethanil application. Pyrimethanil decreased ergosterol concentrations (an indicator of fungal biomass) and the abundance and richness of the macroinvertebrate community associated with decomposing leaves. However, because neither fungi nor macroinvertebrates were main factors contributing to decomposition in this particular system, organic matter processing rates were not affected. After 274 days, pyrimethanil concentration in the water column was ≤0.004 mg L−1 but richness, biomass and composition of the invertebrate community associated with decomposing leaf-litter still showed the effect. The comparison of ergosterol (a molecule existing on both algae and fungal cell membranes), with chlorophyll (an indicator of algal biomass) associated with biofilm suggests that pyrimethanil may decrease fungal biomass and alter the relative abundance of algae and fungi on biofilm developing in control- and treated-mesocosms.
KeywordsFungicide Anilinopyrimidine Aquatic ecosystem Decomposition Macroinvertebrates Biofilm
Authors wish to thank Dr. Ruth Müller (Institute of Occupational, Social and Environmental Medicine, Goethe University) for the determination of pyrimethanil concentrations in the water samples and overall guidance in the mesocosm study, Ana Gonçalves (IMAR-CMA, University of Coimbra) for help with the ergosterol extraction, and Jorge Varejão (Instituto Politécnico de Coimbra, Escola Superior Agrária, CERNAS) for the help with ergosterol analysis. We also thank two anonymous revisers for the constructive suggestions on an earlier version of the manuscript. This work was partially financed by the European Fund for Economic and Regional Development (FEDER) through the Program Operational Factors of Competitiveness (COMPETE) and National Funds through the Portuguese Foundation for Science and Technology (postdoctoral fellowships to C. Shinn - SFRH/BPD/78642/2011, Ciência 2007 - POPH and QREN, and the research Project PTDC/AAC-AMB/103547/2008), and through the annual funds attributed to the R&D institution IMAR-CMA, University of Coimbra.
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Conflict of interest
The authors declare that they have no conflict of interest.
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