1
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Moncelon R, Metzger E, Pineau P, Emery C, Bénéteau E, de Lignières C, Philippine O, Robin FX, Dupuy C. Drivers for primary producers' dynamics: New insights on annual benthos pelagos monitoring in anthropised freshwater marshes (Charente-Maritime, France). WATER RESEARCH 2022; 221:118718. [PMID: 35749922 DOI: 10.1016/j.watres.2022.118718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/03/2022] [Accepted: 06/04/2022] [Indexed: 06/15/2023]
Abstract
Wetlands, especially marshes, support many services such as carbon catchment control or water purification led by primary producers such as phytoplankton and microphytobenthos (PB). The impact of the sedimentary compartment, as source and sink of essential nutrients for the water column, is often neglected in the study of their dynamics and water purification capacity of the systems. This work compared monthly (between February 2020 and April 2021) the benthic and pelagic primary producers' dynamics in two anthropised freshwater marshes (Marans and Genouillé), with the simultaneous follow-up of physico-chemical parameters of the water column and nutrient fluxes at the sediment-water (SWI) interface. It was suggested a strong contribution of phytoplankton (pumping) and the benthic compartment (denitrification) to the water purification of these two nitrates (NO3-)-rich marshes. Total phytoplankton production fluctuated between ∼5 (winter) and 1500 mg C m-3 d-1 (fall) at Marans and between 40 (winter) and ∼750 mg C m-3 d-1 (spring) at Genouillé. At Marans, soluble reactive phosphorus (SRP) benthic effluxes (-2.101 to -6.102 µmol m-2 d-1 in fall and summer, respectively) coincided with phytoplankton bloom periods. These effluxes were inhibited by NO3- penetration in the sediment (0 to 5.104 µmol m-2 d-1), by inhibiting iron respiration. At Genouillé, inhibition of SRP effluxes depended on denitrification rate and on P stocks in the sediment, where slight SRP effluxes (-101 µmol m-2 d-1) could have co-occurred with slight NO3- influxes (5.102 µmol m-2 d-1) in spring. The presence of PB (between 10-60 and 40-120 mg gsed-1 at Marans and Genouillé, respectively), suggested a strong contribution of the benthic compartment to the total primary production (benthic and pelagic through resuspension processes) in these environments. This work encourages to consider the benthos and the pelagos as a unicum to provide better sustainable management of such systems and limit eutrophication risks in coastal areas.
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Affiliation(s)
- Raphaël Moncelon
- Laboratoire LIENSs, UMR 7266, La Rochelle Université, Bâtiment ILE, 2 Rue Olympe de Gouges, La Rochelle, France.
| | - Edouard Metzger
- Laboratoire de Planétologie et Géosciences, CNRS, Université d'Angers, Nantes Université, Le Mans Université, Angers, France
| | - Philippe Pineau
- Laboratoire LIENSs, UMR 7266, La Rochelle Université, Bâtiment ILE, 2 Rue Olympe de Gouges, La Rochelle, France
| | - Claire Emery
- Laboratoire LIENSs, UMR 7266, La Rochelle Université, Bâtiment ILE, 2 Rue Olympe de Gouges, La Rochelle, France
| | - Eric Bénéteau
- Laboratoire de Planétologie et Géosciences, CNRS, Université d'Angers, Nantes Université, Le Mans Université, Angers, France
| | - Charlotte de Lignières
- Laboratoire LIENSs, UMR 7266, La Rochelle Université, Bâtiment ILE, 2 Rue Olympe de Gouges, La Rochelle, France
| | | | | | - Christine Dupuy
- Laboratoire LIENSs, UMR 7266, La Rochelle Université, Bâtiment ILE, 2 Rue Olympe de Gouges, La Rochelle, France
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2
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Haro S, Jesus B, Oiry S, Papaspyrou S, Lara M, González CJ, Corzo A. Microphytobenthos spatio-temporal dynamics across an intertidal gradient using Random Forest classification and Sentinel-2 imagery. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 804:149983. [PMID: 34517311 DOI: 10.1016/j.scitotenv.2021.149983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 07/07/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
Microphytobenthos (MPB) provides important ecosystem functions and services, contributing significantly to the total primary production in shallow coastal ecosystems. However, determining the factors that regulate the seasonal changes of MPB and its distribution patterns at larger scales is hindered by the considerable spatial and temporal variability in these environments. Here, we studied the dynamics of intertidal MPB biomass, cover, and net growth rates in a south European tidal flat (Cadiz Bay, Spain) over a four-year period using the Normalized Difference Vegetation Index (NDVI) calculated from Sentinel-2 satellite images. Pixels dominated by different benthic communities (MPB, Zostera sp., Caulerpa sp. and green macroalgae) were identified at a 10-m resolution using a Random Forest (RF) machine learning classification algorithm. MPB dominated the intertidal zone. MPB cover did not show a clear seasonal pattern and was clearly higher in the middle of the intertidal range of sea level. Despite interannual variability, MPB biomass was always higher during winter, coinciding with observations from other low latitude intertidal flats with temperate climate, and in the upper-middle intertidal. Net rates of MPB biomass change, calculated from the differences in MPB NDVI over time, showed maximal net growth rates from autumn to winter and maximum loss rates during spring and summer, although with high variability. Our study demonstrates that RF algorithms allow mapping MPB and other intertidal communities from Sentinel-2 multispectral satellite imagery accurately obtaining invaluable information from large areas at very high spatio-temporal resolution. The dissimilarities observed in the patterns of MPB variables over time or sea level, indicate differences in their ecological regulation, still largely unknown both here and in other temperate climate intertidal flats. High resolution remote sensing can aid in their detailed and systematic study producing a more integrated view of these systems and contributing to their science-based management and conservation.
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Affiliation(s)
- S Haro
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz, Spain.
| | - B Jesus
- Université de Nantes, Faculté des Sciences, Mer-Molécules-Santé (MMS), RSBE, EA2160 Nantes, France.
| | - S Oiry
- Université de Nantes, Faculté des Sciences, Mer-Molécules-Santé (MMS), RSBE, EA2160 Nantes, France.
| | - S Papaspyrou
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz, Spain.
| | - M Lara
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz, Spain.
| | - C J González
- Division of Naval Support and Oceanography, Marine Hydrographic Institute, Spanish Navy, 11007 Cadiz, Spain.
| | - A Corzo
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz, Spain.
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3
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Gu YG, Wang Y, Ouyang J, Jordan RW, Jiang S. Impacts of coastal aquaculture on sedimentary phosphorus speciation and fate: Evidence from a seaweed cultivation area off Nan'ao Island, South China. MARINE POLLUTION BULLETIN 2021; 171:112719. [PMID: 34343755 DOI: 10.1016/j.marpolbul.2021.112719] [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: 02/18/2021] [Revised: 06/27/2021] [Accepted: 07/09/2021] [Indexed: 06/13/2023]
Abstract
How aquaculture impacts the coastal phosphorus (P) cycle remains poorly understood. Here we compared different P species from two sedimentary records off Nan'ao Island, South China, with core S1 collected in a large seaweed cultivation area and core S2 in a non-mariculture area. The results showed that the concentration of total P (TP) in sediment cores varied from 143.67 to 400.92 μg/g, and organic P (OP) was the dominant P species. The TOC/OP ratios in the two sediment cores were higher than the Redfield ratio in 26 samples (52%) from core S1 and 39 samples (78%) from core S2, suggesting that terrestrial organic matter was an important carbon source to Shen'ao Bay. The lack of change in Ex-P (exchangeable or loosely sorbed P) and OP in the area around core S1 since the 2000s may be due to the large-scale seaweed cultivation.
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Affiliation(s)
- Yang-Guang Gu
- College of Life Science and Technology/Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, China; South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China
| | - Yasu Wang
- College of Life Science and Technology/Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China
| | - Jun Ouyang
- Hainan Provincial Ecological and Ecological and Environmental Monitoring Center, Haikou 570000, China
| | - Richard W Jordan
- Faculty of Science, Yamagata University, Yamagata 990-8560, Japan
| | - Shijun Jiang
- College of Life Science and Technology/Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China.
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4
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Zhou Y, Wang L, Zhou Y, Mao XZ. Eutrophication control strategies for highly anthropogenic influenced coastal waters. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 705:135760. [PMID: 31806305 DOI: 10.1016/j.scitotenv.2019.135760] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/21/2019] [Accepted: 11/24/2019] [Indexed: 06/10/2023]
Abstract
Rapid economic development and urbanization necessitate an understanding of anthropogenic effects on coastal eutrophication. It is a significant challenge for governments to alleviate water degradation and remediate coastal ecosystems. Shenzhen Bay in China, located in a developed and populous area, was selected to analyze the decadal scale influence of anthropogenic activities on eutrophication as well as the effectiveness of governmental remediation strategies. The results showed that the contribution of nutrients from anthropogenic sources accounted for over 80% of the total loads into the bay. Beginning in 1990, increased anthropogenic activities resulted in the loss of environmental capability and resilience, exacerbated eutrophication and water quality degradation. However, the status of eutrophication has been improved since 2005, following the application of intensive management actions implemented in 2000. The practice of eutrophication control suggested that, in view of technical and engineering feasibility, coastal strategies for similar shallow bays should initially reduce phosphorus, followed by nitrogen and eco-remediation to alleviate the serious aquatic situation immediately. The recovery period of eutrophication would be at least five years after governmental actions from Shenzhen Bay's experience. Furthermore, simulated scenarios indicated that eutrophication ranking of Shenzhen Bay could reach and remains medium Moderate, following a 35% reduction in total nitrogen and a 20% reduction in total phosphorus with corresponding eco-remediation.
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Affiliation(s)
- Yun Zhou
- Shenzhen International Graduate School, Tsinghua University, Shenzhen, PR China
| | - Linlin Wang
- Shenzhen International Graduate School, Tsinghua University, Shenzhen, PR China
| | - Yanyan Zhou
- Shenzhen International Graduate School, Tsinghua University, Shenzhen, PR China
| | - Xian-Zhong Mao
- Shenzhen International Graduate School, Tsinghua University, Shenzhen, PR China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), PR China.
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5
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Haro S, Bohórquez J, Lara M, Garcia-Robledo E, González CJ, Crespo JM, Papaspyrou S, Corzo A. Diel patterns of microphytobenthic primary production in intertidal sediments: the role of photoperiod on the vertical migration circadian rhythm. Sci Rep 2019; 9:13376. [PMID: 31527648 PMCID: PMC6746711 DOI: 10.1038/s41598-019-49971-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 08/01/2019] [Indexed: 02/08/2023] Open
Abstract
Diel primary production patterns of intertidal microphytobenthos (MPB) have been attributed to short-term physiological changes in the photosynthetic apparatus or to diel changes in the photoautotrophic biomass in the sediment photic layer due to vertical migration. Diel changes in primary production and vertical migration are entrained by external factors like photoperiod and tides. However, the role of photoperiod and tides has not been experimentally separated to date. Here, we performed laboratory experiments with sediment cores kept in immersion, in the absence of tides, with photoperiod or under continuous light. Measurements of net production, made with O2 microsensors, and of spectral reflectance at the sediment surface showed that, in intertidal sediments, the photoperiod signal was the major driver of the diel patterns of net primary production and sediment oxygen availability through the vertical migration of the MPB photoautotrophic biomass. Vertical migration was controlled by an endogenous circadian rhythm entrained by photoperiod in the absence of tides. The pattern progressively disappeared after 3 days in continuous light but was immediately reset by photoperiod. Even though a potential contribution of a subjective in situ tidal signal cannot be completely discarded, Fourier and cross spectral analysis of temporal patterns indicated that the photosynthetic circadian rhythm was mainly characterized by light/dark migratory cycles.
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Affiliation(s)
- S Haro
- Department of Biology, University of Cádiz, Puerto Real, 11510, Spain. .,Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR). Campus Universitario de Puerto Real, Puerto Real (Cádiz), 11510, Spain.
| | - J Bohórquez
- Department of Biology, University of Cádiz, Puerto Real, 11510, Spain.,Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR). Campus Universitario de Puerto Real, Puerto Real (Cádiz), 11510, Spain
| | - M Lara
- Department of Biology, University of Cádiz, Puerto Real, 11510, Spain.,Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR). Campus Universitario de Puerto Real, Puerto Real (Cádiz), 11510, Spain
| | - E Garcia-Robledo
- Department of Biology, University of Cádiz, Puerto Real, 11510, Spain.,Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR). Campus Universitario de Puerto Real, Puerto Real (Cádiz), 11510, Spain
| | - C J González
- Division of Naval Support and Oceanography, Marine Hydrographic Institute, Spanish Navy, Cadiz, Spain
| | - J M Crespo
- Department of Biology, University of Cádiz, Puerto Real, 11510, Spain
| | - S Papaspyrou
- Department of Biology, University of Cádiz, Puerto Real, 11510, Spain.,Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR). Campus Universitario de Puerto Real, Puerto Real (Cádiz), 11510, Spain
| | - A Corzo
- Department of Biology, University of Cádiz, Puerto Real, 11510, Spain.,Instituto Universitario de Investigación Marina (INMAR), Universidad de Cádiz, Campus de Excelencia Internacional del Mar (CEIMAR). Campus Universitario de Puerto Real, Puerto Real (Cádiz), 11510, Spain
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6
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Rakotomalala C, Guizien K, Grangeré K, Lefebvre S, Dupuy C, Orvain F. Modelling the functioning of a coupled microphytobenthic-EPS-bacterial system in intertidal mudflats. MARINE ENVIRONMENTAL RESEARCH 2019; 150:104754. [PMID: 31299542 DOI: 10.1016/j.marenvres.2019.104754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 06/25/2019] [Accepted: 07/02/2019] [Indexed: 06/10/2023]
Abstract
A mechanistic and biogeochemical model was developed to analyze the interactions between microphytobenthos (MPB), bacteria and nutrients in a tidal system. Behavioral vertical migration was hypothesized as being controlled by exogenous factors (tide and light) but also by endogenous factors (carbon and nitrogen requirements). The secretion of Extracellular Polymeric Substances (EPS) during photosynthesis (overflow metabolism) and migration of diatoms was also formulated. Similarities in MPB dynamics between observations and simulations support the assumption that carbon and nitrogen ratios are additional key processes behind the vertical migration of diatoms in the sediment. The model satisfactorily reproduced the three growth phases of the MPB development observed in a mesocosm (the lag phase, the logarithmic growth, and the plateau). Besides, nutrient availability, which could be induced by faunal bioturbation, significantly determined the extent of MPB biomass and development. The plateau phase observed in the last days of simulations appeared to be attributed to a nutrient depletion in the system, emphasizing the importance of nutrient availability. The model, although improvable especially on the formulation of the EPS excretion and bacteria development, already updated understanding of several aspects of benthic-system functioning during experimental conditions.
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Affiliation(s)
- C Rakotomalala
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) Université de Caen-Normandie, Esplanade de la Paix, 14032, Caen, France.
| | - K Guizien
- Sorbonne Université-CNRS, UMR 8222, LECOB, Laboratoire d'Ecogéochimie des Environnements Benthiques, rue du Fontaulé, F-66650, Banyuls/mer, France
| | - K Grangeré
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) Université de Caen-Normandie, Esplanade de la Paix, 14032, Caen, France
| | - S Lefebvre
- Université de Lille, CNRS, Université du Littoral Côte d'Opale, UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, F-62930, Wimereux, France
| | - C Dupuy
- Université de la Rochelle-CNRS, UMR 7266, Littoral Environnement et Sociétés (LIENSs), 2 rue Olympe de Gouges, 17000, La Rochelle cedex, France
| | - F Orvain
- Laboratoire de Biologie des Organismes et Ecosystèmes Aquatiques (BOREA) Université de Caen-Normandie, Esplanade de la Paix, 14032, Caen, France
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7
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Bohórquez J, Calenti D, García-Robledo E, Papaspyrou S, Jimenez-Arias JL, Gómez-Ramírez EH, Corzo A. Water column dissolved silica concentration limits microphytobenthic primary production in intertidal sediments. JOURNAL OF PHYCOLOGY 2019; 55:625-636. [PMID: 30671969 DOI: 10.1111/jpy.12838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 01/04/2019] [Indexed: 06/09/2023]
Abstract
Primary production of microphytobenthos (MPB) contributes significantly to the total production in shallow coastal environments. MPB is a diverse community in which diatoms are usually the main microalgal group. Diatoms require N, P, and other nutrients as with other autotrophs, but in addition require silicate to create their outer cell wall. Therefore, dissolved silica (DSi) might be a potential limiting factor for benthic primary production in areas with reduced freshwater input. To test this hypothesis, a microcosm experiment was conducted using intact sediment cores collected from an intertidal mudflat in the Bay of Cádiz and supplied with increasing concentrations of DSi (0, 5, 10, 25, and 45 μmol · L-1 ). After 7 d of enrichment, we determined chlorophyll a and c (Chl a, c) contents, metabolic rates (Net [Pn ] and Areal Gross [PgA ] Production and Light [RL ] and Dark [RD ] Respiration), as well as fluxes of inorganic nutrients across the sediment-water interface. Chl a and c contents increased significantly with respect to the initial conditions but no differences between treatments were found. Both Pn and PgA showed a saturating-like pattern with silicate concentration, reaching maximum rates at a DSi concentration of 45 μmol · L-1 . The addition of DSi also resulted in an increase of DSi and ammonium uptake by the sediment, which was significantly higher in light than in darkness. Our results clearly show that water column DSi concentrations have a direct impact on benthic primary production, also controlling other related processes such as inorganic nutrient fluxes.
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Affiliation(s)
- Julio Bohórquez
- Department of Biology, Faculty of Marine and Environmental Science, University of Cádiz, Pol. Río San Pedro s/n, 11510, Puerto Real, Spain
| | - Danielle Calenti
- Department of Biology, Faculty of Marine and Environmental Science, University of Cádiz, Pol. Río San Pedro s/n, 11510, Puerto Real, Spain
| | - Emilio García-Robledo
- Department of Biology, Faculty of Marine and Environmental Science, University of Cádiz, Pol. Río San Pedro s/n, 11510, Puerto Real, Spain
| | - Sokratis Papaspyrou
- Departamento de Biomedicina, Biotecnología y Salud Publica, Universidad de Cádiz, Polígono Rio San Pedro s/n, 11510, Puerto Real, Spain
| | - Juan Luis Jimenez-Arias
- Department of Biology, Faculty of Marine and Environmental Science, University of Cádiz, Pol. Río San Pedro s/n, 11510, Puerto Real, Spain
| | | | - Alfonso Corzo
- Department of Biology, Faculty of Marine and Environmental Science, University of Cádiz, Pol. Río San Pedro s/n, 11510, Puerto Real, Spain
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8
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Kamp A, Petro C, Røy H, Nielsen S, Carvalho P, Stief P, Schramm A. Intracellular nitrate in sediments of an oxygen-deficient marine basin is linked to pelagic diatoms. FEMS Microbiol Ecol 2018; 94:5040219. [PMID: 29931199 DOI: 10.1093/femsec/fiy122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/15/2018] [Indexed: 11/13/2022] Open
Abstract
Intracellular nitrate is an important electron acceptor in oxygen-deficient aquatic environments, either for the nitrate-storing microbes themselves, or for ambient microbial communities through nitrate leakage. This study links the spatial distribution of intracellular nitrate with the abundance and identity of nitrate-storing microbes in sediments of the Bornholm Basin, an environmental showcase for severe hypoxia. Intracellular nitrate (up to 270 nmol cm-3 sediment) was detected at all 18 stations along a 35-km transect through the basin and typically extended as deep as 1.6 cm into the sediment. Intracellular nitrate contents were particularly high at stations where chlorophyll contents suggested high settling rates of pelagic primary production. The depth distribution of intracellular nitrate matched that of the diatom-specific photopigment fucoxanthin in the upper 1.6 cm and calculations support that diatoms are the major nitrate-storing microbes in these sediments. In contrast, other known nitrate-storing microbes, such as sulfide-oxidizing bacteria and foraminifers, played only a minor role, if any. Strikingly, 18S rRNA gene sequencing revealed that the majority of the diatoms in the sediment were pelagic species. We conclude that intracellular nitrate stored by pelagic diatoms is transported to the seafloor by settling phytoplankton blooms, implying a so far overlooked 'biological nitrate pump'.
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Affiliation(s)
- Anja Kamp
- AIAS, Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark.,Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Caitlin Petro
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Hans Røy
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Susanne Nielsen
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Pedro Carvalho
- Department of Environmental Science, Aarhus University, Roskilde, Denmark
| | - Peter Stief
- Nordcee, Department of Biology, University of Southern Denmark, Odense, Denmark
| | - Andreas Schramm
- Center for Geomicrobiology and Section for Microbiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
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9
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Høgslund S, Cedhagen T, Bowser SS, Risgaard-Petersen N. Sinks and Sources of Intracellular Nitrate in Gromiids. Front Microbiol 2017; 8:617. [PMID: 28473806 PMCID: PMC5397464 DOI: 10.3389/fmicb.2017.00617] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/27/2017] [Indexed: 11/27/2022] Open
Abstract
A substantial nitrate pool is stored within living cells in various benthic marine environments. The fate of this bioavailable nitrogen differs according to the organisms managing the intracellular nitrate (ICN). While some light has been shed on the nitrate carried by diatoms and foraminiferans, no study has so far followed the nitrate kept by gromiids. Gromiids are large protists and their ICN concentration can exceed 1000x the ambient nitrate concentration. In the present study we investigated gromiids from diverse habitats and showed that they contained nitrate at concentrations ranging from 1 to 370 mM. We used 15N tracer techniques to investigate the source of this ICN, and found that it originated both from active nitrate uptake from the environment and from intracellular production, most likely through bacterial nitrification. Microsensor measurements showed that part of the ICN was denitrified to N2 when gromiids were exposed to anoxia. Denitrification seemed to be mediated by endobiotic bacteria because antibiotics inhibited denitrification activity. The active uptake of nitrate suggests that ICN plays a role in gromiid physiology and is not merely a consequence of the gromiid hosting a diverse bacterial community. Measurements of aerobic respiration rates and modeling of oxygen consumption by individual gromiid cells suggested that gromiids may occasionally turn anoxic by their own respiration activity and thus need strategies for coping with this self-inflicted anoxia.
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Affiliation(s)
- Signe Høgslund
- Department of Bioscience, Aarhus UniversityAarhus, Denmark
| | - Tomas Cedhagen
- Department of Bioscience, Aarhus UniversityAarhus, Denmark
| | - Samuel S Bowser
- Wadsworth Center, New York State Department of Health, AlbanyNY, USA
| | - Nils Risgaard-Petersen
- Department of Bioscience, Aarhus UniversityAarhus, Denmark.,Center for Geomicrobiology, Aarhus UniversityAarhus, Denmark
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10
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Bohórquez J, McGenity TJ, Papaspyrou S, García-Robledo E, Corzo A, Underwood GJC. Different Types of Diatom-Derived Extracellular Polymeric Substances Drive Changes in Heterotrophic Bacterial Communities from Intertidal Sediments. Front Microbiol 2017; 8:245. [PMID: 28289404 PMCID: PMC5326797 DOI: 10.3389/fmicb.2017.00245] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 02/06/2017] [Indexed: 11/18/2022] Open
Abstract
Intertidal areas support extensive diatom-rich biofilms. Such microphytobenthic (MPB) diatoms exude large quantities of extracellular polymeric substances (EPS) comprising polysaccharides, glycoproteins and other biopolymers, which represent a substantial carbon pool. However, degradation rates of different EPS components, and how they shape heterotrophic communities in sediments, are not well understood. An aerobic mudflat-sediment slurry experiment was performed in the dark with two different EPS carbon sources from a diatom-dominated biofilm: colloidal EPS (cEPS) and the more complex hot-bicarbonate-extracted EPS. Degradation rate constants determined over 9 days for three sediment fractions [dissolved organic carbon (DOC), total carbohydrates (TCHO), and (cEPS)] were generally higher in the colloidal-EPS slurries (0.105–0.123 d−1) compared with the hot-bicarbonate-extracted-EPS slurries (0.060–0.096 d−1). Addition of hot-bicarbonate-EPS resulted in large increases in dissolved nitrogen and phosphorous by the end of the experiment, indicating that the more complex EPS is an important source of regenerated inorganic nutrients. Microbial biomass increased ~4–6-fold over 9 days, and pyrosequencing of bacterial 16S rRNA genes revealed that the addition of both types of EPS greatly altered the bacterial community composition (from 0 to 9 days) compared to a control with no added EPS. Bacteroidetes (especially Tenacibaculum) and Verrucomicrobia increased significantly in relative abundance in both the hot-bicarbonate-EPS and colloidal-EPS treatments. These differential effects of EPS fractions on carbon-loss rates, nutrient regeneration and microbial community assembly improve our understanding of coastal-sediment carbon cycling and demonstrate the importance of diverse microbiota in processing this abundant pool of organic carbon.
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Affiliation(s)
- Julio Bohórquez
- Department of Biology, Faculty of Marine and Environmental Science, University of CádizPuerto Real, Spain; School of Biological Sciences, University of EssexColchester, UK
| | - Terry J McGenity
- School of Biological Sciences, University of Essex Colchester, UK
| | - Sokratis Papaspyrou
- Departamento de Biomedicina, Biotecnología y Salud Publica, Universidad de Cádiz Puerto Real, Spain
| | - Emilio García-Robledo
- Department of Biology, Faculty of Marine and Environmental Science, University of CádizPuerto Real, Spain; Microbiology Section, Department of Biosciences, University of AarhusAarhus, Denmark
| | - Alfonso Corzo
- Department of Biology, Faculty of Marine and Environmental Science, University of Cádiz Puerto Real, Spain
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