Direct and indirect toxicity of the fungicide pyraclostrobin to Hyalella azteca and effects on leaf processing under realistic daily temperature regimes. (April 2016)

• Record Type: Journal Article
• Authors: Willming, Morgan M.; Maul, Jonathan D.
• Is Part Of: Environmental pollution. Volume 211(2016)
• Page Start: 435
• Page End: 442
• Publication Date: 2016-04
• Subjects: Fungicides -- Diurnal temperature -- Organic matter decomposition -- Climate change; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2015.11.029
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Fungicides in aquatic environments can impact non-target bacterial and fungal communities and the invertebrate detritivores responsible for the decomposition of allochthonous organic matter. Additionally, in some aquatic systems daily water temperature fluctuations may influence these processes and alter contaminant toxicity, but such temperature fluctuations are rarely examined in conjunction with contaminants. In this study, the shredding amphipod Hyalella azteca was exposed to the fungicide pyraclostrobin in three experiments. Endpoints included mortality, organism growth, and leaf processing. One experiment was conducted at a constant temperature (23 °C), a fluctuating temperature regime (18–25 °C) based on field-collected data from the S. Llano River, Texas, or an adjusted fluctuating temperature regime (20–26 °C) based on possible climate change predictions. Pyraclostrobin significantly reduced leaf shredding and increased H. azteca mortality at concentrations of 40 μg/L or greater at a constant 23 °C and decreased leaf shredding at concentrations of 15 μg/L or greater in the fluctuating temperatures. There was a significant interaction between temperature treatment and pyraclostrobin concentration on H. azteca mortality, body length, and dry mass under direct aqueous exposure conditions. In an indirect exposure scenario in which only leaf material was exposed to pyraclostrobin, H. azteca did not preferentially feed on or avoid treated leaf disks compared to controls. This study describes the influence of realistic temperature variation on fungicide toxicity to shredding invertebrates, which is important for understanding how future alterations in daily temperature regimes due to climate change may influence the assessment of ecological risk of contaminants in aquatic ecosystems. Highlights: Pyraclostrobin was directly toxic to Hyalella azteca and reduced leaf processing. Indirect exposure via leaf material did not change H. azteca feeding or growth. Realistic daily temperature fluctuations altered toxicity and growth endpoints. Contaminant risk may vary for organisms in thermally variable environments. Abstract : Interaction of fungicide exposure and realistic fluctuating daily temperature regimes can alter leaf processing and growth of the shredding amphipod Hyalella azteca .