title: The sediment-contact test using the ostracod Heterocypris incongruens: Effect of fine sediments and determination of toxicity thresholds.
abstract: The toxicity test using freshwater ostracods of the species Heterocypris incongruens is a sub-chronic static test that exposes individuals to whole sediments over a period of 6 d, the endpoints being mortality and growth. We tested the hypothesis that endpoints of the sediment bioassay using Heterocypris incongruens are affected by the presence of fine sediment particles by testing control sediment supplied with the commercial test kit with increasing proportions of kaolin clay as a proxy for fines. While mortality was not affected, the results showed that increasing the presence of clay reduced ostracod growth. Based on the variability in growth, a sublethal toxicity threshold of 35% is proposed to distinguish effects due to sediment properties from those due to toxicity. The relevance of this threshold was verified using data from toxicity tests of ambient sediment samples with low levels of contamination.
authors.affiliation: Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Station 2 (GR B0 391), 1015 Lausanne, Switzerland. Electronic address: carmen.casado@centreecotox.ch.
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Casado-Martinez
authors.affiliation: Université de Lorraine (UdL), Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC) - UMR 7360 CNRS, Campus Bridoux, Bât. IBiSE, 8, rue du Général Delestraint, 57070 Metz, France.
authors.forename: Karen F
authors.initials: KF
authors.lastname: Burga-Pérez
authors.affiliation: Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Station 2 (GR B0 391), 1015 Lausanne, Switzerland.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Bebon
authors.affiliation: Université de Lorraine (UdL), Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC) - UMR 7360 CNRS, Campus Bridoux, Bât. IBiSE, 8, rue du Général Delestraint, 57070 Metz, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Férard
authors.affiliation: Swiss Centre for Applied Ecotoxicology Eawag/EPFL, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Etienne L M
authors.initials: EL
authors.lastname: Vermeirssen
authors.affiliation: Swiss Centre for Applied Ecotoxicology Eawag/EPFL, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Inge
authors.initials: I
authors.lastname: Werner
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D003445:Crustacea / Q000187:drug effects*; D054750:Ecotoxicology / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry*; D018675:Toxicity Tests / Q000379:methods*
keywords: Clay content; Grain size; Ostracodtoxkit(®); Sediment toxicity; Toxicity threshold