title: Polycyclic aromatic hydrocarbons alter the structure of oceanic and oligotrophic microbial food webs.
abstract: One way organic pollutants reach remote oceanic regions is by atmospheric transport. During the Malaspina-2010 expedition, across the Atlantic, Indian, and Pacific Oceans, we analyzed the polycyclic aromatic hydrocarbon (PAH) effects on oceanic microbial food webs. We performed perturbation experiments adding PAHs to classic dilution experiments. The phytoplankton growth rates were reduced by more than 5 times, being Prochlorococcus spp. the most affected. 62% of the experiments showed a reduction in the grazing rates due to the presence of PAHs. For the remaining experiments, grazing usually increased likely due to cascading effects. We identified changes in the slope of the relation between the growth rate and the dilution fraction induced by the pollutants, moving from no grazing to V-shape, or to negative slope, indicative of grazing increase by cascade effects and alterations of the grazers' activity structure. Our perturbation experiments indicate that PAHs could influence the structure oceanic food-webs structure.
authors.affiliation: Department of Global Change Research, IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Avanzados, Miquel Marqués 21, 07190 Esporles, Spain. Electronic address: mcerezo@imedea.uib-csic.es.
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Cerezo
authors.affiliation: Department of Global Change Research, IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Avanzados, Miquel Marqués 21, 07190 Esporles, Spain; Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia. Electronic address: susana.agusti@kaust.edu.sa.
authors.forename: Susana
authors.initials: S
authors.lastname: Agusti
mesh_terms: D001267:Atlantic Ocean; D020387:Food Chain; D060434:Herbivory; D019156:Indian Ocean; D010140:Pacific Ocean; D010839:Phytoplankton / Q000187:drug effects / Q000254:growth & development*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000633:toxicity; D048929:Prochlorococcus / Q000187:drug effects; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical
keywords: Grazing; Microbial food webs; Oceanic communities; PAHs; Phytoplankton growth