title: Realistic environmental mixtures of hydrophobic compounds do not alter growth of a marine diatom.
abstract: In this paper we determine whether a realistic mixture of hydrophobic chemicals affects the growth dynamics of a marine diatom and how this effect compares to the effect of temperature, light regime and nutrient conditions. To do so, we examine the specific growth rate of Phaeodactylum tricornutum in a 72 h algal growth inhibition test using a full factorial design with three nutrient regimes, two test temperatures, three light intensities and three chemical exposures. Passive samplers were used to achieve exposure to realistic mixtures of organic chemicals close to ambient concentrations. Nutrient regime, temperature and time interval (24, 48 and 72 h) explained 85% of the observed variability in the experimental data. The variability explained by chemical exposure was about 1%. Overall, ambient concentrations of hydrophobic compounds present in Belgian coastal waters, and for which the passive samplers have affinity, are too low to affect the intrinsic growth rate of P. tricornutum.
authors.affiliation: Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, Ghent, Belgium. Electronic address: Gert.Everaert@UGent.be.
authors.forename: Gert
authors.initials: G
authors.lastname: Everaert
authors.affiliation: Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur, Belgium.
authors.forename: Frederik
authors.initials: F
authors.lastname: De Laender
authors.affiliation: DuPont de Nemours, Mechelen, Belgium.
authors.forename: Michiel
authors.initials: M
authors.lastname: Claessens
authors.affiliation: Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, Ghent, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Baert
authors.affiliation: Management Unit of the North Sea Mathematical Model, Royal Belgian Institute of Natural Sciences, Ostend, Belgium.
authors.forename: Els
authors.initials: E
authors.lastname: Monteyne
authors.affiliation: Management Unit of the North Sea Mathematical Model, Royal Belgian Institute of Natural Sciences, Ostend, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Roose
authors.affiliation: Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, Ghent, Belgium.
authors.forename: Peter L M
authors.initials: PL
authors.lastname: Goethals
authors.affiliation: Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, Ghent, Belgium.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Janssen
mesh_terms: D017377:Diatoms / Q000187:drug effects / Q000254:growth & development*; D004777:Environment; D004781:Environmental Exposure; D057927:Hydrophobic and Hydrophilic Interactions; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000494:pharmacology*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Ecotoxicological effect; Marine diatom; Mixture toxicity; Passive sampling