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Feiler U.,Federal Institute of Hydrology | Ratte M.,ToxRat Solutions GmbH | Arts G.,Wageningen University | Bazin C.,INSAVALOR Division POLDEN | And 20 more authors.
Environmental Toxicology and Chemistry | Year: 2014

A whole-sediment toxicity test with Myriophyllum aquaticum has been developed by the German Federal Institute of Hydrology and standardized within the International Organization for Standardization (ISO; ISO 16191). An international ring-test was performed to evaluate the precision of the test method. Four sediments (artificial, natural) were tested. Test duration was 10 d, and test endpoint was inhibition of growth rate (r) based on fresh weight data. Eighteen of 21 laboratories met the validity criterion of r≥0.09 d-1 in the control. Results from 4 tests that did not conform to test-performance criteria were excluded from statistical evaluation. The inter-laboratory variability of growth rates (20.6%-25.0%) and inhibition (26.6%-39.9%) was comparable with the variability of other standardized bioassays. The mean test-internal variability of the controls was low (7% [control], 9.7% [solvent control]), yielding a high discriminatory power of the given test design (median minimum detectable differences [MDD] 13% to 15%). To ensure these MDDs, an additional validity criterion of CV≤15% of the growth rate in the controls was recommended. As a positive control, 90mg 3,5-dichlorophenol/kg sediment dry mass was tested. The range of the expected growth inhibition was proposed to be 35±15%. The ring test results demonstrated the reliability of the ISO 16191 toxicity test and its suitability as a tool to assess the toxicity of sediment and dredged material. Environ Toxicol Chem 2014;33:662-670. © 2013 SETAC.

Stegger P.,Institute fur Gewasserschutz MESOCOSM GmbH | Ebke K.P.,Institute fur Gewasserschutz MESOCOSM GmbH | Rombke J.,ECT Oekotoxikologie GmbH
Journal of Soils and Sediments | Year: 2011

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. © 2010 Springer-Verlag.

Janz P.,Institute fur Gewasserschutz MESOCOSM GmbH | Weltje L.,BASF | Ebke K.P.,Institute fur Gewasserschutz MESOCOSM GmbH | Dawo U.,TU Munich
Hydrobiologia | Year: 2016

The predatory larvae of the phantom midge Chaoborus are considered a key factor for zooplankton community structure in freshwater ecosystems. This study analysed C. crystallinus population dynamics and its influence on the zooplankton community structure in ponds by means of different methods of multivariate statistics based on data collected from 19 mesocosm studies over a period of 14 years. Usually, there were three Chaoborus generations per year in the evaluated studies. According to redundancy analysis the population structure of C. crystallinus varied significantly between years and seasons (within a year). Ordination analysis indicated that C. crystallinus had a significant long-term impact on the zooplankton community structure but this impact was weak when compared to time-related factors. The fourth larval stage had the greatest influence on the zooplankton community. C. crystallinus promoted high densities of rotifers and reduced the abundance of small crustaceans (copepods and small cladocerans). The abundance of large cladocerans such as daphnids was unaffected by the number of C. crystallinus larvae. There was no indication that the predatory impact of C. crystallinus on zooplankton substantially influenced phytoplankton. This study provides new findings to a better understanding of impacts on the pelagic food web related to Chaoborus predation. © 2015, Springer International Publishing Switzerland.

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