title: Taxonomic and functional diversity of a coastal planktonic bacterial community in a river-influenced marine area.
abstract: The Gulf of Naples is a dynamical area with intense exchanges between offshore oligotrophic and coastal eutrophic waters with frequent freshwater inputs. The Sarno River, one of the most polluted rivers in Europe, strongly contributes to the pollution of the area, discharging high amounts of heavy metals and organic wastes from heavily cultivated and industrial areas. This paper reports on the diversity and community structure of the marine residential Bacteria and Archaea of the Gulf of Naples in an area close to the river Sarno plume and investigates their small-scale taxonomic diversity and expression patterns as a proxy of potential metabolic activity using metagenomics and metatranscriptomics. Bacteria and Archaea were mainly represented by marine clades, with only minor contributors from freshwater ones. The community was dominated by Alpha- and Gammaproteobacteria, of which Rhodospirillales, Pelagibacteriales, and Oceanospirilalles were most represented. However, Alteromonadales and Rhodobacterales were the most active, despite their relative lower abundance, suggesting that they are important for overall ecosystem functioning and nutrient cycling. Nitrification and a reversed form of dissimilatory sulfate reduction were the major metabolic processes found in the metatrascriptomes and were mainly associated to Nitrosopumilales and Pelagibacter, respectively. No clear indication of transcripts related to stress induced by heavy metals or organic pollutants was found. In general, despite the high loads of pollutants discharged continuously by the Sarno River, the microbial community did not show marks of stress-induced changes neither structural nor functional, thus suggesting that this river has little or no effect on the planktonic bacterial community of the Gulf of Naples.
authors.affiliation: Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
authors.forename: Stefan
authors.initials: S
authors.lastname: Thiele
authors.affiliation: Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Richter
authors.affiliation: Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Balestra
authors.affiliation: Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany; Jacobs University Bremen gGmbH, Campus Ring 1, 28759 Bremen, Germany.
authors.forename: Frank Oliver
authors.initials: FO
authors.lastname: Glöckner
authors.affiliation: Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy. Electronic address: raffaella.casotti@szn.it.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Casotti
mesh_terms: D001105:Archaea / Q000145:classification*; D001419:Bacteria / Q000145:classification*; D007558:Italy; D008522:Mediterranean Sea; D064307:Microbiota; D010933:Plankton / Q000145:classification*; D019642:RNA, Archaeal / Q000235:genetics; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D054712:Salinity
chemical_list: D019642:RNA, Archaeal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012337:RNA, Ribosomal, 18S
keywords: Gulf of Naples; High throughput sequencing; Mediterranean Sea; Microbial ecology; Sarno River