TY - JOUR A1 - Reeg, Jette A1 - Heine, Simon A1 - Mihan, Christine A1 - Preuss, Thomas G. A1 - McGee, Sean A1 - Jeltsch, Florian T1 - Potential impact of effects on reproductive attributes induced by herbicides on a plant community JF - Environmental Toxicology and Chemistry N2 - Current herbicide risk assessment guidelines for nontarget terrestrial plants require testing effects on young, vulnerable life stages (i.e., seedling emergence [and subsequent growth] and vegetative vigor [growth and dry wt]) but not directly on the reproduction of plants. However, the European Food Safety Authority (EFSA) has proposed that effects on reproduction might be considered when evaluating the potential effects on plants. We adapted the plant community model for grassland (IBC-grass) to give insight into the current debate on the sensitivity of reproductive versus vegetative endpoints in ecological risk assessment. In an extensive sensitivity analysis of this model, we compared plant attributes potentially affected by herbicides and the consequences for long-term plant population dynamics and plant diversity. This evaluation was implemented by reducing reproductive as well as vegetative endpoints by certain percentages (e.g., 10-90%) as a theoretical assumption. Plant mortality and seed sterility (i.e., inability of seeds to germinate) were the most sensitive attributes. Our results indicated that effects on seed production at off-field exposure rates must be very strong to have an impact on the risk assessment. Otherwise, effects on seed production are compensated for by the soil seed bank. The present study highlights the usefulness of community level modeling studies to support regulators in their decisions on the appropriate risk assessment endpoints and provides confidence in their assessments. Environ Toxicol Chem 2018;37:1707-1722. (c) 2018 SETAC KW - Ecological risk assessment KW - Ecotoxicology KW - Herbicide KW - Plant reproduction KW - Plant community model KW - Nontarget terrestrial plants Y1 - 2018 U6 - https://doi.org/10.1002/etc.4122 SN - 0730-7268 SN - 1552-8618 VL - 37 IS - 6 SP - 1707 EP - 1722 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Spijkerman, Elly A1 - Behrend, Hella A1 - Fach, Bettina A1 - Gaedke, Ursula T1 - Decreased phosphorus incorporation explains the negative effect of high iron concentrations in the green microalga Chlamydomonas acidophila JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - The green microalga Chlamydomonas acidophila is an important primary producer in very acidic lakes (pH 2.0-3.5), characterized by high concentrations of ferric iron (up to 1 g total Fe L-1) and low rates of primary production. It was previously suggested that these high iron concentrations result in high iron accumulation and inhibit photosynthesis in C. acidophila. To test this, the alga was grown in sterilized lake water and in medium with varying total iron concentrations under limiting and sufficient inorganic phosphorus (Pi) supply, because Pi is an important growth limiting nutrient in acidic waters. Photosynthesis and growth of C. acidophila as measured over 5 days were largely unaffected by high total iron concentrations and only decreased if free ionic Fe3+ concentrations exceeded 100 mg Fe3+ L-1. Although C. acidophila was relatively rich in iron (up to 5 mmol Fe: mol C), we found no evidence of iron toxicity. In contrast, a concentration of 260 mg total Fe L-1 (i.e. 15 mg free ionic Fe3+ L-1), which is common in many acidic lakes, reduced Pi-incorporation by 50% and will result in Pi-limited photosynthesis. The resulting Pi-limitation present at high iron and Pi concentrations was illustrated by elevated maximum Pi-uptake rates. No direct toxic effects of high iron were found, but unfavourable chemical Pi-speciation reduced growth of the acidophile alga. KW - Chlamydomonas KW - Ecotoxicology KW - Extreme environment KW - Iron toxicity KW - Phosphate limitation KW - Phytoplankton Y1 - 2018 U6 - https://doi.org/10.1016/j.scitotenv.2018.01.188 SN - 0048-9697 SN - 1879-1026 VL - 626 SP - 1342 EP - 1349 PB - Elsevier CY - Amsterdam ER -