title: Impact of a simulated oil spill on benthic phototrophs and nitrogen-fixing bacteria in mudflat mesocosms.
abstract: Coastal and estuarine ecosystems are highly susceptible to crude oil pollution. Therefore, in order to examine the resilience of benthic phototrophs that are pivotal to coastal ecosystem functioning, we simulated an oil spill in tidal mesocosms consisting of intact sediment cores from a mudflat at the mouth of the Colne Estuary, UK. At day 21, fluorescence imaging revealed a bloom of cyanobacteria on the surface of oiled sediment cores, and the upper 1.5 cm thick sediment had 7.2 times more cyanobacterial and 1.7 times more diatom rRNA sequences when treated with oil. Photosystem II operating efficiency (Fq'/Fm') was significantly reduced in oiled sediments at day 7, implying that the initial diatom-dominated community was negatively affected by oil, but this was no longer apparent by day 21. Oil addition significantly reduced numbers of the key deposit feeders, and the decreased grazing pressure is likely to be a major factor in the increased abundance of both diatoms and cyanobacteria. By day 5 concentrations of dissolved inorganic nitrogen were significantly lower in oiled mesocosms, likely resulting in the observed increase in nifH-containing, and therefore potentially dinitrogen-fixing, cyanobacteria. Thus, indirect effects of oil, rather than direct inhibition, are primarily responsible for altering the microphytobenthos.
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
authors.forename: Panagiota-Myrsini
authors.initials: PM
authors.lastname: Chronopoulou
authors.forename: Anne
authors.initials: A
authors.lastname: Fahy
authors.forename: Frédéric
authors.initials: F
authors.lastname: Coulon
authors.forename: Sandrine
authors.initials: S
authors.lastname: Païssé
authors.forename: Marisol
authors.initials: M
authors.lastname: Goñi-Urriza
authors.forename: Louis
authors.initials: L
authors.lastname: Peperzak
authors.forename: Laura
authors.initials: L
authors.lastname: Acuña Alvarez
authors.forename: Boyd A
authors.initials: BA
authors.lastname: McKew
authors.forename: Tracy
authors.initials: T
authors.lastname: Lawson
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Timmis
authors.forename: Robert
authors.initials: R
authors.lastname: Duran
authors.forename: Graham J C
authors.initials: GJ
authors.lastname: Underwood
authors.forename: Terry J
authors.initials: TJ
authors.lastname: McGenity
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D058491:Bacterial Load; D044822:Biodiversity; D000458:Cyanobacteria / Q000235:genetics; D017377:Diatoms / Q000235:genetics / Q000502:physiology; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010088:Oxidoreductases / Q000235:genetics; D010578:Petroleum; D059392:Petroleum Pollution; D045332:Photosystem II Protein Complex / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D010578:Petroleum; D045332:Photosystem II Protein Complex; D014874:Water Pollutants, Chemical; D010088:Oxidoreductases; C029130:nitrogenase reductase