title: Sub-lethal effects of water-based drilling muds on the deep-water sponge Geodia barretti.
abstract: Offshore oil and gas activities can result in the discharge of large amounts of drilling muds. While these materials have generally been regarded as non-toxic to marine organisms, recent studies have demonstrated negative impacts to suspension feeding organisms. We exposed the arctic-boreal sponge Geodia barretti to the primary particulate components of two water-based drilling muds; barite and bentonite. Sponges were exposed to barite, bentonite and a natural reference sediment at a range of total suspended solid concentrations (TSS = 0, 10, 50 or 100 mg/L) for 12 h after which we measured a suite of biomarker responses (lysosomal membrane stability, lipid peroxidation and glutathione). In addition, we compared biomarker responses, organic energy content and metal accumulation in sponges, which had been continuously or intermittently exposed to suspended barite and natural sediment for 14 d at relevant concentrations (10 and 30 mg TSS/L). Lysosomal membrane stability was reduced in the sponges exposed to barite at 50 and 100 mg TSS/L after just 12 h and at 30 mg TSS/L for both continuous and intermittent exposures over 14 d. Evidence of compromised cellular viability was accompanied by barite analysis revealing concentrations of Cu and Pb well above reference sediments and Norwegian sediment quality guidelines. Metal bioaccumulation in sponge tissues was low and the total organic energy content (determined by the elemental composition of organic tissue) was not affected. Intermittent exposures to barite resulted in less toxicity than continuous exposure to barite. Short term exposures to bentonite did not alter any biomarker responses. This is the first time that these biomarkers have been used to indicate contaminant exposure in an arctic-boreal sponge. Our results illustrate the potential toxicity of barite and the importance of assessments that reflect the ways in which these contaminants are delivered under environmentally realistic conditions.
authors.affiliation: Evolution and Ecology Research Centre, School of Biological and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: katelyn.edge@environment.nsw.gov.au.
authors.forename: Katelyn J
authors.initials: KJ
authors.lastname: Edge
authors.affiliation: Evolution and Ecology Research Centre, School of Biological and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia; Sydney Institute of Marine Science, Chowder Bay Rd, Mosman, NSW 2088, Australia.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Johnston
authors.affiliation: Evolution and Ecology Research Centre, School of Biological and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Dafforn
authors.affiliation: Centre for Environmental Contaminants Research, CSIRO Land and Water, Locked Bag 2007, Kirrawee, NSW 2232, Australia.
authors.forename: Stuart L
authors.initials: SL
authors.lastname: Simpson
authors.affiliation: Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway.
authors.forename: Tina
authors.initials: T
authors.lastname: Kutti
authors.affiliation: Institute of Marine Research, PO Box 1870, 5817 Bergen, Norway.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Bannister
mesh_terms: D000818:Animals; D001466:Barium Sulfate; D001546:Bentonite; D019652:Extraction and Processing Industry; D047231:Geodia / Q000187:drug effects*; D019015:Geologic Sediments / Q000737:chemistry*; D007220:Industrial Waste; D008247:Lysosomes; D008670:Metals / Q000737:chemistry / Q000378:metabolism; D009664:Norway; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D007220:Industrial Waste; D008670:Metals; D014874:Water Pollutants, Chemical; D001546:Bentonite; D001466:Barium Sulfate
keywords: Biomarkers; Contaminants; Oil drilling; Sponges; Suspended sediments