| Title | Natural and anthropogenic disturbances shape benthic phototrophic and heterotrophic microbial communities in the Po River Delta system |
| Abstract | This study represents the first example in which benthic heterotrophic and photoautotrophic microbial communities (prokaryotes and microphytobenthos-MPB, respectively) were simultaneously investigated. To explore how they synergistically respond to multiple natural and anthropogenic stressors, in the framework of the Project RITMARE four lagoons of the Po River Delta were sampled in May 2016: two with more marine features, i.e. Scardovari (SC) and Caleri (CL), and two more directly affected by the Po River flow, i.e. Canarin (CN) and Vallona-Marinetta (MV). The abundance and structure of benthic communities were related to physical-chemical parameters i.e. grain-size, total N, total organic C, stable C and N isotopes, and synthetic organic contaminants. Stations were gathered into three distinct groups (R-ansosim = 0.540 p < 0.001) according to their different physical-chemical features: outer, inner-freshwater and inner-marine sites. Contamination levels did not seem to severely affect the microbial abundances that were overall stimulated by the combined effect of high organic and nutrient loads: prokaryotes up to + 42% and MPB up to +93%. Bacteria and Archaea displayed high densities at sites directly influenced by the freshwater input and anthropogenically derived nitrogen. Delta- (30.8%), Alpha- (12.8%), Gamma- (11.8%) and Beta-Proteobacteria (7.1%) were the dominant classes at all sites. For both communities, a significant inter-lagoonal (among different lagoons) and infra-lagoonal (among stations within the same lagoon) pattern was highlighted by PERMANOVA. nMDS and SIMPER analyses revealed distinct assemblages in the inner and outer parts of the lagoons. We applied a novel functional approach based on diatom life modes. At inner and outer sites, different diatom living forms developed: epipsammic (on sand) nearby the lagoonal mouths, epipelic (on mud) at the innermost sites and non-benthic forms (planktonic, tychopelagic and epiphytic) at sites directly influenced by freshwater. Distance-based Linear Models further indicated that salinity, clay and temperature were the significant drivers of the prokaryotic spatial distribution whereas clay, PAHs, PCBs and salinity best explained the MPB structure. The dominance of non-benthic diatom life modes in the more polluted lagoon (CN) suggests a negative influence of contamination on the MPB structure. Two diatom keystone species likely contribute to restore the oxic gradient in sediments frequently exposed to anoxia, allowing the subsequent microbial aerobic degradation and the recolonization of higher trophic organisms. The capacity of re-oxygenation after anoxia has important ecological and economic implications in lagoons exploited for aquaculture. |
| Source | Estuarine, coastal and shelf science (Print) 222, pp. 168–182 |
| Keywords | Microbial diversityMicrophytobenthosBacteriaCoastal lagoonFreshwater inputOrganic enrichmentContaminationAnoxia |
| Journal | Estuarine, coastal and shelf science (Print) |
| Editor | Academic Press in association with the Estuarine and Brackish-water Sciences Association,, New York, Stati Uniti d'America |
| Year | 2019 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.ecss.2019.04.009 |
| Authors | Cibic, Tamara; Fazi, Stefano; Nasi, Federica; Pin, Lorenzo; Alvisi, Francesca; Berto, Daniela; Vigano, Luigi; Zoppini, Annamaria; Del Negro, Paola |
| Text | 403353 2019 10.1016/j.ecss.2019.04.009 ISI Web of Science WOS 000468256400017 Microbial diversity Microphytobenthos Bacteria Coastal lagoon Freshwater input Organic enrichment Contamination Anoxia Natural and anthropogenic disturbances shape benthic phototrophic and heterotrophic microbial communities in the Po River Delta system Cibic, Tamara; Fazi, Stefano; Nasi, Federica; Pin, Lorenzo; Alvisi, Francesca; Berto, Daniela; Vigano, Luigi; Zoppini, Annamaria; Del Negro, Paola 1 Ist Nazl Oceanog Geofis Sperimentale OGS, Sez Oceanog, Via A Piccard 54, I 34151 Trieste, Italy 2 Natl Res Council IRSA CNR, Water Res Inst, Via Salaria Km 29,300, I 00015 Rome, Italy 3 Natl Res Council ISMAR CNR, Inst Marine Sci, Via P Gobetti 101, I 40129 Bologna, Italy 4 Inst Environm Protect Res, I 30015 Venice, Italy 5 Natl Res Council IRSA CNR, Water Res Inst, Via Mulino 19, I 20861 Brugherio, Italy This study represents the first example in which benthic heterotrophic and photoautotrophic microbial communities prokaryotes and microphytobenthos MPB, respectively were simultaneously investigated. To explore how they synergistically respond to multiple natural and anthropogenic stressors, in the framework of the Project RITMARE four lagoons of the Po River Delta were sampled in May 2016 two with more marine features, i.e. Scardovari SC and Caleri CL , and two more directly affected by the Po River flow, i.e. Canarin CN and Vallona Marinetta MV . The abundance and structure of benthic communities were related to physical chemical parameters i.e. grain size, total N, total organic C, stable C and N isotopes, and synthetic organic contaminants. Stations were gathered into three distinct groups R ansosim = 0.540 p < 0.001 according to their different physical chemical features outer, inner freshwater and inner marine sites. Contamination levels did not seem to severely affect the microbial abundances that were overall stimulated by the combined effect of high organic and nutrient loads prokaryotes up to 42% and MPB up to 93%. Bacteria and Archaea displayed high densities at sites directly influenced by the freshwater input and anthropogenically derived nitrogen. Delta 30.8% , Alpha 12.8% , Gamma 11.8% and Beta Proteobacteria 7.1% were the dominant classes at all sites. For both communities, a significant inter lagoonal among different lagoons and infra lagoonal among stations within the same lagoon pattern was highlighted by PERMANOVA. nMDS and SIMPER analyses revealed distinct assemblages in the inner and outer parts of the lagoons. We applied a novel functional approach based on diatom life modes. At inner and outer sites, different diatom living forms developed epipsammic on sand nearby the lagoonal mouths, epipelic on mud at the innermost sites and non benthic forms planktonic, tychopelagic and epiphytic at sites directly influenced by freshwater. Distance based Linear Models further indicated that salinity, clay and temperature were the significant drivers of the prokaryotic spatial distribution whereas clay, PAHs, PCBs and salinity best explained the MPB structure. The dominance of non benthic diatom life modes in the more polluted lagoon CN suggests a negative influence of contamination on the MPB structure. Two diatom keystone species likely contribute to restore the oxic gradient in sediments frequently exposed to anoxia, allowing the subsequent microbial aerobic degradation and the recolonization of higher trophic organisms. The capacity of re oxygenation after anoxia has important ecological and economic implications in lagoons exploited for aquaculture. 222 Published version Natural and anthropogenic disturbances shape benthic phototrophic and heterotrophic microbial communities 1_s2_0_S0272771418309727_main.pdf Articolo in rivista Academic Press in association with the Estuarine and Brackish water Sciences Association, 0272 7714 Estuarine, coastal and shelf science Print Estuarine, coastal and shelf science Print Estuar., coast. shelf sci. Print Estuarine, coastal and shelf science. Print stefano.fazi FAZI STEFANO francesca.alvisi ALVISI FRANCESCA luigi.vigano VIGANO LUIGI annamaria.zoppini ZOPPINI ANNAMARIA |
