title: Carbon speciation and composition of natural microbial communities in polluted and pristine sediments of the Eastern Mediterranean Sea.
abstract: Sediment samples collected from polluted (Augusta Bay) and pristine regions of the Eastern Mediterranean Sea (South Ionian Sea, Thracian Sea) were analyzed for black carbon, aliphatic hydrocarbons and phospholipid ester-linked fatty acids (PLFA). The aim of the study was to investigate the anthropogenic and biogenic inputs into the Eastern Mediterranean Sea and to evaluate the effects of refractory organic matter (e.g. black carbon) and the level of hydrocarbon contamination on benthic microbial community composition. Black carbon, generally considered to be chemically and biologically inert, comprised a significant but highly variable fraction of the sedimentary carbon pool in the analyzed sediments with a ratio to total organic carbon ranging from 0.02 to 0.66. Principal component analysis of the chemical characteristics of the sediments (organic carbon content, black carbon, bioavailable organic carbon, chlorophyll a, phaeopigments, aliphatic hydrocarbons) revealed clustering of samples along a gradient from the most productive and contaminated region of Augusta Bay to the carbon-poor and pristine sediments of the Thracian Sea. PLFA analysis revealed that gram-negative bacteria and microeukaryotes were most abundant in Augusta Bay and in the most impacted station of the Thracian Sea. The high levels of branched and odd-chain fatty acids recorded for these stations is probably linked to the elevated amounts of hydrocarbons at these stations; e.g. microbial communities may have developed the ability to degrade either naturally occurring aliphatic hydrocarbons or hydrocarbons derived from oil contamination.
authors.affiliation: Hellenic Centre for Marine Research, Institute of Oceanography, Department of Deep-Sea Ecology, Gournes Pediados, P.O. Box 2214, GR 71003 Heraklion, Crete, Greece. polymen@her.hcmr.gr
authors.forename: Paraskevi N
authors.initials: PN
authors.lastname: Polymenakou
authors.forename: Anastasios
authors.initials: A
authors.lastname: Tselepides
authors.forename: Euripides G
authors.initials: EG
authors.lastname: Stephanou
authors.forename: Stefan
authors.initials: S
authors.lastname: Bertilsson
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D002244:Carbon / Q000032:analysis / Q000737:chemistry*; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000032:analysis*; D005227:Fatty Acids / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis*; D006838:Hydrocarbons / Q000032:analysis; D008522:Mediterranean Sea; D025341:Principal Component Analysis
chemical_list: D004785:Environmental Pollutants; D005227:Fatty Acids; D006838:Hydrocarbons; D002244:Carbon