title: Exposure to crude oil micro-droplets causes reduced food uptake in copepods associated with alteration in their metabolic profiles.
abstract: Acute oil spills and produced water discharges may cause exposure of filter-feeding pelagic organisms to micron-sized dispersed oil droplets. The dissolved oil components are expected to be the main driver for oil dispersion toxicity; however, very few studies have investigated the specific contribution of oil droplets to toxicity. In the present work, the contribution of oil micro-droplet toxicity in dispersions was isolated by comparing exposures to oil dispersions (water soluble fraction with droplets) to concurrent exposure to filtered dispersions (water-soluble fractions without droplets). Physical (coloration) and behavioral (feeding activity) as well as molecular (metabolite profiling) responses to oil exposures in the copepod Calanus finmarchicus were studied. At high dispersion concentrations (4.1-5.6mg oil/L), copepods displayed carapace discoloration and reduced swimming activity. Reduced feeding activity, measured as algae uptake, gut filling and fecal pellet production, was evident also for lower concentrations (0.08mg oil/L). Alterations in metabolic profiles were also observed following exposure to oil dispersions. The pattern of responses were similar between two comparable experiments with different oil types, suggesting responses to be non-oil type specific. Furthermore, oil micro-droplets appear to contribute to some of the observed effects triggering a starvation-type response, manifested as a reduction in metabolite (homarine, acetylcholine, creatine and lactate) concentrations in copepods. Our work clearly displays a relationship between crude oil micro-droplet exposure and reduced uptake of algae in copepods.
authors.affiliation: SINTEF Materials and Chemistry, Environmental Technology, Trondheim, Norway; Norwegian University of Science and Technology, Department of Biology, Trondheim, Norway. Electronic address: bjorn.h.hansen@sintef.no.
authors.forename: Bjørn Henrik
authors.initials: BH
authors.lastname: Hansen
authors.affiliation: BioTrix, Trondheim, Norway.
authors.forename: Dag
authors.initials: D
authors.lastname: Altin
authors.affiliation: SINTEF Materials and Chemistry, Environmental Technology, Trondheim, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Nordtug
authors.affiliation: SINTEF Materials and Chemistry, Environmental Technology, Trondheim, Norway.
authors.forename: Ida Beathe
authors.initials: IB
authors.lastname: Øverjordet
authors.affiliation: Norwegian University of Science and Technology, Department of Biology, Trondheim, Norway.
authors.forename: Anders J
authors.initials: AJ
authors.lastname: Olsen
authors.affiliation: SINTEF Materials and Chemistry, Environmental Technology, Trondheim, Norway.
authors.forename: Dan
authors.initials: D
authors.lastname: Krause
authors.affiliation: Norwegian University of Science and Technology, Department of Biology, Trondheim, Norway.
authors.forename: Ingvild
authors.initials: I
authors.lastname: Størdal
authors.affiliation: SINTEF Materials and Chemistry, Environmental Technology, Trondheim, Norway.
authors.forename: Trond R
authors.initials: TR
authors.lastname: Størseth
mesh_terms: D000818:Animals; D033342:Copepoda / Q000187:drug effects* / Q000378:metabolism; D004435:Eating / Q000187:drug effects; D004781:Environmental Exposure; D055442:Metabolome / Q000187:drug effects; D010578:Petroleum / Q000633:toxicity*; D059392:Petroleum Pollution; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D010578:Petroleum; D014874:Water Pollutants, Chemical
keywords: Copepod filtration; Endogenous metabolites; Metabolite profiling; Micro-droplets; Oil dispersion