Inter-laboratory comparison of five marine bioassays for evaluating the toxicity of dredged material

Abstract

Four laboratories were compared to ascertain the reproducibility of test methods for five bioassays: the ten day whole sediment bioassay with the amphipod Corophium volutator, the fourteen day whole sediment bioassay with adult sea urchins Echinocardium cordatum, the Microtox solid phase bioassay with the bacterium Vibrio fischeri, the oyster larvae sediment elutriate bioassay using Crassostrea gigas and the sediment pore water bioassay with the rotifer Brachionus plicatilis. The bioassays were all conducted according to the standard operating procedures of the National Institute for Coastal and Marine Management/RIKZ and carried out with one control sediment and three moderately contaminated dredged materials from the Netherlands. Reference toxicant tests were also performed for every bioassay, to assess the condition of the test species. Reproducibility and inter-laboratory variability were evaluated by calculating coefficients of variation for the sediment bioassays and considering the ability of each laboratory to achieve the test acceptability criteria and to identify a number of confounding factors. The bioassays involving the amphipods and sea urchins had an acceptable inter-laboratory variability, with average coefficients of variation of 20% or less. The Microtox solid phase bioassay showed high reproducibility and the least variability among laboratories, with average coefficients of variation of 12%. In contrast, the results for percent net response in the oyster larvae bioassay were very variable and poorly reproducible: in three of the four sediments the coefficients of variation exceeded 100%. Two laboratories did not meet the test acceptability criterion for oyster embryo development in the control sediment. Survival in the rotifer bioassay also varied greatly among laboratories with average coefficients of variation of 48%. We conclude that the main sources of inter-laboratory variability were 1) individual differences in the skill and experience of laboratory technicians (for the amphipod, oyster larvae and rotifer bioassays); 2) the use of different batches of test organisms (sea urchin bioassay) and 3) the use of different dilution water (oyster larvae bioassay).

Genotoxicity of diuron and glyphosate in oyster spermatozoa and embryos

“…Of note, and as previously reported for sea urchins (Manzo et al, 2006) and blue mussels (Fitzpatrick et al, 2008) in the case of copper and biocide (diuron, irgarol) exposure, embryotoxicity appears to be a particularly sensitive endpoint for studying the effects of pollutants on development and reproduction. The embryo larval bioassay appears however as a toxicity bioassay that can presents a high variability as demonstrated previously during an inter-laboratory comparison (Stronkhorst et al, 2004). A part of variability is associated to the use of different batches of genitors that may present different pollutant sensitivity.…”

Baseline of butyltin contamination in sediments of Sundarban mangrove wetland and adjacent coastal regions, India

“…All other reagents were obtained from Thermo Fisher UK (Loughborough, UK) and were of analytical grade. Analyses of organotins were conducted according to the standard operating procedures (Stronkhorst et al 2004) by GC-MS (split/splitless injection) and the limit of detection of each component was 1 ng g -1 . For all the analyses, blanks (solvent) and spiked blanks (standards spiked into solvent) were routinely analyzed.…”

Effects of dilution on the exposure in sediment toxicity tests—buffering of freely dissolved concentrations and changes in mixture composition

“…Some of these toxicity tests are conducted by diluting contaminated sediment with clean water or by diluting an aqueous phase (e.g., pore water or aqueous elutriate) with clean water. In these tests, the biological effects are linked to the dilution factor [1–4]. For example, the often‐applied Microtox® test (Strategic Diagnostics, Newark, DE, USA) measures decrease in light production of the marine luminescent bacterium Vibrio fischeri when exposed to suspensions of contaminated sediment (Microtox solid‐phase test) or dilutions of aqueous samples (Microtox test).…”