Background: Parrot feather (Myriophyllum aquaticum) is an amphibious macrophyte with an inducible heterophylly. M. aquaticum plants adapted to the emersed state have leaves with a distinct cuticle and water repellent properties. In contrast M. aquaticum plants adapted to the submerged state have leaves typical for submerged hydrophytes with a strongly reduced cuticle. The aim of the study was to evaluate if this heterophylly of M. aquaticum affects the results of macrophyte biotests. Therefore, the two model substances atrazine and 2,4-dichlorophenoxyacetic acid (2,4-D) were tested each with three M. aquaticum biotests, the only modified parameter being the adaptation time to submergence (0, 7, 28 days). Results: Root length was the most sensitive growth endpoint regarding the test substances atrazine and 2,4-D. Biotests with plants adapted to the submerged state show three times more sensitive results (EC50 7d 142.2 μg/L, EC50 28d 154.5 μg/L) than biotests with plants without an adaptation phase (EC50 0d 458.8 μg/L) in case of atrazine and five times more sensitive results (EC50 28d 46.9 μg/L, EC50 0d 246.3 μg/L) in case of 2,4-D. Apart from the differences in sensitivity, the differently adapted M. aquaticum plants show a completely different growth behavior. The growth rates based on shoot length were nearly ten times higher in the biotests with not adapted M. aquaticum plants than in the biotests with plants 28 days adapted to submergence. Additional measurements of the quantum yield of PSII could demonstrate that rapid growth in length is not based on photosynthetic carbon assimilation. Conclusions: The heterophylly of M. aquaticum affects significantly the sensitivity of aquatic macrophyte biotests and should be taken into account in the development of a standardized test design. The 2,4-D results show the importance of an additional macrophyte biotest to the Lemna test, where the no observed effect concentration (NOEC) value is more than 30 times lower (7 μg/L) than the NOEC value of Lemna in the literature (270 μg/L). Furthermore, the growth rate endpoint in macrophyte biotests should not be misinterpreted. Rapid shoot elongation of amphibious macrophytes, which become submerged, is mainly caused by ethylene-triggered endogenous processes that are not connected to photosynthetic carbon assimilation and appear to be part of a stress reaction to avoid adverse environmental conditions.

Purpose Boric acid was applied in an earthworm field test according to ISO 11268-3 as a possible alternative for the currently used reference substances that may no longer be available in the near future. Material and methods The test site was a pasture with a silt-and clay-dominated soil, a pH of 5.7 and an organic content of 2.8%. In addition to a water-only control, two separate treatments of boric acid were applied: single applications at rates of 187 and 750 kg/ha. In order to investigate the acute impact of this compound, biological sampling was undertaken 4 weeks after application by hand sorting combined with formaldehyde extraction. Results and discussion The earthworm community consisted of seven species commonly found at German grassland sites. In the control plots, mean abundance was very high: 984 individuals per square metre before application and 390 individuals per square metre 4 weeks following application of boric acid. In the treated plots, abundance and biomass were reduced by more than 50% compared to the control plots, respectively. In general, juvenile earthworms as well as the epigeic species were affected most strongly.Conclusions On the basis of this study, boric acid has the potential to be an alternative reference substance in assessing the acute impact on earthworm species in field tests.

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Background: In mesocosms, the fate and effects of chemicals can be investigated under more realistic conditions than in laboratory-scale experiments and most mesocosm studies for higher-tier risk assessment are conducted in lentic test systems. However, particularly for the assessment of EPT taxa (Ephemeroptera, Plecoptera, Trichoptera) and gammarids (Amphipoda), which are considered to be ecologically vulnerable macroinvertebrates, lotic systems seem to be more appropriate. Within this pilot study, eight newly constructed stream mesocosms were tested for their suitability in the effect assessment of plant protection products (PPP). By using the insecticide carbaryl as an example test item, five concentrations without replicates were tested under a worst case exposure scenario and three stream mesocosms served as controls. Results: 15 out of the 51 invertebrate taxa found during the study belonged to EPT taxa, while the common lotic amphipod Gammarus sp. (G. pulex and G. roesili) was the most dominant taxa. Estimation of minimum detectable differences based on mean abundances and variance of taxa in the eight mesocosms before application indicate that for five arthropoda taxa and two non-arthropoda taxa, an analysis of effects would have probably would have been possible in a typical test design for a higher-tier study with more test units. Five of these taxa were typical stream taxa, i.e. mayflies, caddisflies and gammarids. With respect to the effects of carbaryl, multivariate analysis (principal response curve) indicates long-term effects on the macroinvertebrates community over several weeks for the highest carbaryl concentration (120 µg a.i./L). Potential effects were observed for the amphipod Gammarus sp., the mayfly Ephemera danica and the caddisfly family Limnephilidae. Conclusions: Through this study it was shown that the stream mesocosms provided suitable habitats for potential sensitive and vulnerable taxa, including those typical for lotic systems. To enable a reliable statistical analysis of the effects within the higher-tier ecological risk assessment, the number of stream mesocosms needs to be enhanced. In addition, colonisation and sampling should be improved to increase the number of taxa with sufficiently high abundances for evaluation.

This article gives a comprehensive overview on the strategy, the development and the progress of the German postgraduate degree program in ecotoxicology (SETAC GLB and GDCh). The program soon prompted positive results: more than 10 years now the courses had an average enrolment rate of 90 %, and employment-seeking graduates from the first courses mostly succeeded in quickly finding employment relevant to their training. With over 450 students enrolled to date, the degree program contributes significantly to the field of Environmental Chemistry and Ecotoxicology.Electronic supplementary materialThe online version of this article (doi:10.1186/s12302-016-0078-5) contains supplementary material, which is available to authorized users.