title: Sediment-preserved diatom assemblages can distinguish a petroleum activity signal separately from the nutrient signal of the Mississippi River in coastal Louisiana.
abstract: We analyzed the preserved diatom assemblages in dated sediment cores collected from five locations in the Louisiana Bight to test if there was a signature of petroleum extraction activities (hopanes and barium) distinct from the well-documented effects of nutrient loading. The results of a multi-dimensional scaling analysis indicate that the diatom assemblage changes documented throughout the 40 year record could be explained by three variables: barium and hopanes concentrations, and Mississippi River nitrogen loading. The results of a canonical correspondence analysis demonstrated that these signals could be distinguished through correlations with specific diatom species. The abundance of Actinoptychus senarius, for example, was negatively correlated with barium and the Pseudo-nitzschia delicatissima complex was positively correlated with nitrogen loading. These results provide a "proof-of-concept" demonstration that diatom assemblages preserved in the sediments can be used to study the effects of petroleum extraction activities, and that these 'petroleum signals' may be distinguished from other significant influences such as nutrient loading.
authors.affiliation: Coastal Watershed Institute, Florida Gulf Coast University, 10501 FGCU Blvd. South, Fort Myers, FL 33965, USA. Electronic address: mparsons@fgcu.edu.
authors.forename: M L
authors.initials: ML
authors.lastname: Parsons
authors.affiliation: Department of Oceanography and Coastal Sciences, Coastal Ecology Institute, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Turner
authors.affiliation: Department of Environmental Studies, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: E B
authors.initials: EB
authors.lastname: Overton
mesh_terms: D000062:Accidents, Occupational; D017377:Diatoms / Q000302:isolation & purification*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis; D005068:Eutrophication; D005843:Geography; D019015:Geologic Sediments; D060851:Gulf of America; D008145:Louisiana; D009584:Nitrogen / Q000032:analysis; D010578:Petroleum / Q000032:analysis*; D059392:Petroleum Pollution; D011157:Population Dynamics; D045483:Rivers; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004785:Environmental Pollutants; D010578:Petroleum; D014874:Water Pollutants, Chemical; D009584:Nitrogen
keywords: Eutrophication; Gulf of Mexico; Hypoxia; Oil spill; Phytoplankton