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Riekenberg PM, Oakes JM, Eyre BD. A shift in the pool of retained microphytobenthos nitrogen under enhanced nutrient availability. WATER RESEARCH 2020; 187:116438. [PMID: 33070037 DOI: 10.1016/j.watres.2020.116438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/28/2020] [Accepted: 09/18/2020] [Indexed: 06/11/2023]
Abstract
Sediment microbial communities are an important sink for both organic and inorganic nitrogen (N), with microphytobenthos (MPB) biomass making the largest contribution to short-term N-assimilation and retention. Coastal waters are increasingly subject to anthropogenic nutrient enrichment, but the effect of nutrient enrichment on microbial assimilation, processing, and fate of MPB-derived N (MPB-N) remains poorly characterised. In this study, an MPB-dominated microbial community was labeled in situ with a pulse of 15NH4+-N. Laboratory core incubations of this labeled sediment under increasing nutrient concentrations (NH4+ and PO43-: ambient, 2 × ambient, 5 × ambient, and 10 × ambient) were used to investigate changes in the processing and flux pathways of the 15N-labeled MPB-N across 10.5 d under nutrient enrichment. Short-term retention of MPB-N by MPB was stimulated by nutrient addition, with higher 15N in MPB in the nutrient amended treatments (71-93%) than in the ambient treatment (38%) at 0.5 d After 10.5 d, the nutrient amended treatments had increased turnover of MPB-N out of MPB biomass into an uncharacterised pool of sediment ON (45-75%). Increased turnover of MPB-N likely resulted from decreased recycling of MPB-N between MPB and heterotrophic bacteria as inorganic nutrients were preferentially used as an N source and remineralisation of sediment ON decreased. Decreased breakdown of sediment ON reduced the efflux of MPB-N via DON in the amended (3.9-5.2%) versus the ambient treatment (10.9%). Exports of MPB-N to the water column were relatively small, accounting for a maximum of 14% of 15N exported from the sediment, and were predominantly exported DON and N2 (denitrification). Overall, there was considerable retention of MPB-N over 10.5 d, but increased nutrient loading shifted N from MPB biomass into other sediment ON.
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Affiliation(s)
- Philip M Riekenberg
- Centre for Coastal Biogeochemistry, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; NIOZ, Royal Netherlands Institute for Sea Research and Utrecht University, Department of Marine Microbiology and Biogeochemistry, PO Box 59, Den Hoorn, 1790AB, Netherlands.
| | - Joanne M Oakes
- Centre for Coastal Biogeochemistry, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia
| | - Bradley D Eyre
- Centre for Coastal Biogeochemistry, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia
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Jordan SFA, Treude T, Leifer I, Janßen R, Werner J, Schulz-Vogt H, Schmale O. Bubble-mediated transport of benthic microorganisms into the water column: Identification of methanotrophs and implication of seepage intensity on transport efficiency. Sci Rep 2020; 10:4682. [PMID: 32170164 PMCID: PMC7070025 DOI: 10.1038/s41598-020-61446-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 02/05/2020] [Indexed: 11/17/2022] Open
Abstract
Benthic microorganisms transported into the water column potentially influence biogeochemical cycles and the pelagic food web structure. In the present study six gas-releasing vent sites in the Coal Oil Point seep field (California) were investigated, and the dislocation of microorganisms from the sediment into the water column via gas bubbles released from the seabed was documented. It was found that the methanotrophs transport efficiency was dependent on the volumetric gas flow, with the highest transport rate of 22.7 × 103 cells mLgas−1 at a volumetric gas flow of 0.07 mLgas s−1, and the lowest rate of 0.2 × 103 cells mLgas−1 at a gas flow of 2.2 mLgas s−1. A simple budget approach showed that this bubble-mediated transport has the potential to maintain a relevant part of the water-column methanotrophs in the seep field. The bubble-mediated link between the benthic and pelagic environment was further supported by genetic analyses, indicating a transportation of methanotrophs of the family Methylomonaceae and oil degrading bacteria of the genus Cycloclasticus from the sediment into the water column. These findings demonstrate that the bubble-mediated transport of microorganisms influences the pelagic microbial abundance and community composition at gas-releasing seep sites.
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Affiliation(s)
| | - Tina Treude
- University of California, Los Angeles Department of Earth, Planetary, and Space Sciences, Los Angeles, California, USA
| | - Ira Leifer
- Bubbleology Research International, Solvang, California, USA
| | - René Janßen
- Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany
| | - Johannes Werner
- Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany
| | - Heide Schulz-Vogt
- Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany
| | - Oliver Schmale
- Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany.
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Frank H, Fussmann KE, Rahav E, Bar Zeev E. Chronic effects of brine discharge form large-scale seawater reverse osmosis desalination facilities on benthic bacteria. WATER RESEARCH 2019; 151:478-487. [PMID: 30641463 DOI: 10.1016/j.watres.2018.12.046] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/15/2018] [Accepted: 12/08/2018] [Indexed: 06/09/2023]
Abstract
Seawater desalination facilities continuously discharge hyper-saline brine into the coastal environment which often flows as a concentrated plume over the seafloor, hence possibly impacting benthic microorganisms. Yet, the effects of brine discharge from desalination plants on benthic bacteria, key players in biodegradation of organic material and nutrient recycling is unknown. In this study, we tested the chronic (years) effects of brine discharge from three large-scale desalination facilities on the abundance, metabolic activity and community composition of benthic bacteria. To this end, four sampling campaigns were carried at the outfall areas of the Ashkelon, Sorek and Hadera desalination facilities. The effects of the brine were compared to corresponding reference stations which were not influenced by the brine (i.e., water temperature and salinity). Our sampling data indicate that bacterial abundance and activity that includes bacterial growth efficiency were 1.3-2.6-fold higher at the outfall area than the reference station. Concomitant analysis pointed out that the bacterial community structure at the brine discharge area was also different than the reference station, yet varied between each desalination facility. Our results demonstrate that the impact of brine effluent from desalination facilities on benthic bacteria are site-specific and localized (<1.4 Km2) around the discharge point. Namely, that the effects on benthic bacteria are prominent at the brine mixing zone and change according to the discharge method used to disperse the brine as well as local stressors (e.g., eutrophication and elevated water temperature). Our results contribute new insights on the effects of desalination-brine to benthic microbes, while providing scientifically-based aspects on the ecological impacts of brine dispersion for decision makers.
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Affiliation(s)
- Hila Frank
- Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research (BIDR) Ben-Gurion University of the Negev, 84990, Israel; Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, 8030, Israel
| | - Katarina E Fussmann
- Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research (BIDR) Ben-Gurion University of the Negev, 84990, Israel; Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, 8030, Israel
| | - Eyal Rahav
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, 8030, Israel.
| | - Edo Bar Zeev
- Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research (BIDR) Ben-Gurion University of the Negev, 84990, Israel.
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Conte A, Papale M, Amalfitano S, Mikkonen A, Rizzo C, De Domenico E, Michaud L, Lo Giudice A. Bacterial community structure along the subtidal sandy sediment belt of a high Arctic fjord (Kongsfjorden, Svalbard Islands). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 619-620:203-211. [PMID: 29149744 DOI: 10.1016/j.scitotenv.2017.11.077] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 11/07/2017] [Accepted: 11/07/2017] [Indexed: 06/07/2023]
Abstract
Open fjords are subject to contrasting environmental conditions, owing to meltwater glacial inputs, terrestrial runoff, and marine water mass exchanges, which are exacerbated by anthropogenic and climate perturbations. Following a slope-dependent water circulation, the subtidal sandy sediment belt regulates the convergent transport of nutrients downward the fjord depths, and the effective entrapment of suspended particles and microorganisms. In this study, we aimed at testing how glacial and seawater inputs may influence the bacterial community structure of subtidal sand deposits in the Kongsfjorden. Through total and viable cell counting and an amplicon sequencing approach, we found relevant differences in bacterial community structure along the glacio-marine sampling transect. Viable and high nucleic acid content (HNA) cells represented an important fraction of the total community, generally decreasing toward the glacier front. Besides the predominance of Alpha- and Gammaproteobacteria, Bacteroidetes, Firmicutes and Parcubacteria, the bacterial community structure was likely affected by the glacial activity in the inner fjord, with the occurrence of distinctive phylotypes belonging to Gemmatimonadates, Nitrospirae, Acidobacteria, and Chloroflexi. Overall, our outcomes highlighted that exploring the bacterial community distribution and structure can provide new insights into the active role of sand deposits in coastal cold environments.
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Affiliation(s)
- Antonella Conte
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Maria Papale
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Stefano Amalfitano
- Water Research Institute, National Research Council (IRSA-CNR), Monterotondo, Rome, Italy
| | - Anu Mikkonen
- Department of Biological and Environmental Sciences, University of Jyvaskyla, Jyvaskyla, Finland
| | - Carmen Rizzo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Emilio De Domenico
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Luigi Michaud
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Angelina Lo Giudice
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy; Institute for the Coastal Marine Environment, National Research Council (IAMC-CNR), Messina, Italy.
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