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Stenow R, Robertson EK, Kourtchenko O, Whitehouse MJ, Pinder MIM, Benvenuto G, Töpel M, Godhe A, Ploug H. Resting cells of Skeletonema marinoi assimilate organic compounds and respire by dissimilatory nitrate reduction to ammonium in dark, anoxic conditions. Environ Microbiol 2024; 26:e16625. [PMID: 38653479 DOI: 10.1111/1462-2920.16625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 04/05/2024] [Indexed: 04/25/2024]
Abstract
Diatoms can survive long periods in dark, anoxic sediments by forming resting spores or resting cells. These have been considered dormant until recently when resting cells of Skeletonema marinoi were shown to assimilate nitrate and ammonium from the ambient environment in dark, anoxic conditions. Here, we show that resting cells of S. marinoi can also perform dissimilatory nitrate reduction to ammonium (DNRA), in dark, anoxic conditions. Transmission electron microscope analyses showed that chloroplasts were compacted, and few large mitochondria had visible cristae within resting cells. Using secondary ion mass spectrometry and isotope ratio mass spectrometry combined with stable isotopic tracers, we measured assimilatory and dissimilatory processes carried out by resting cells of S. marinoi under dark, anoxic conditions. Nitrate was both respired by DNRA and assimilated into biomass by resting cells. Cells assimilated nitrogen from urea and carbon from acetate, both of which are sources of dissolved organic matter produced in sediments. Carbon and nitrogen assimilation rates corresponded to turnover rates of cellular carbon and nitrogen content ranging between 469 and 10,000 years. Hence, diatom resting cells can sustain their cells in dark, anoxic sediments by slowly assimilating and respiring substrates from the ambient environment.
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Affiliation(s)
- Rickard Stenow
- Department of Marine Sciences, University of Gothenburg, Gothenburg, SE, Sweden
| | | | - Olga Kourtchenko
- Department of Marine Sciences, University of Gothenburg, Gothenburg, SE, Sweden
| | | | - Matthew I M Pinder
- Department of Marine Sciences, University of Gothenburg, Gothenburg, SE, Sweden
| | | | - Mats Töpel
- Department of Marine Sciences, University of Gothenburg, Gothenburg, SE, Sweden
- IVL-Swedish Environmental Research Institute, Gothenburg, SE, Sweden
| | - Anna Godhe
- Department of Marine Sciences, University of Gothenburg, Gothenburg, SE, Sweden
| | - Helle Ploug
- Department of Marine Sciences, University of Gothenburg, Gothenburg, SE, Sweden
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Gain G, Berne N, Feller T, Godaux D, Cenci U, Cardol P. Induction of photosynthesis under anoxic condition in Thalassiosira pseudonana and Euglena gracilis: interactions between fermentation and photosynthesis. FRONTIERS IN PLANT SCIENCE 2023; 14:1186926. [PMID: 37560033 PMCID: PMC10407231 DOI: 10.3389/fpls.2023.1186926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 06/28/2023] [Indexed: 08/11/2023]
Abstract
INTRODUCTION In their natural environment, microalgae can be transiently exposed to hypoxic or anoxic environments. Whereas fermentative pathways and their interactions with photosynthesis are relatively well characterized in the green alga model Chlamydomonas reinhardtii, little information is available in other groups of photosynthetic micro-eukaryotes. In C. reinhardtii cyclic electron flow (CEF) around photosystem (PS) I, and light-dependent oxygen-sensitive hydrogenase activity both contribute to restoring photosynthetic linear electron flow (LEF) in anoxic conditions. METHODS Here we analyzed photosynthetic electron transfer after incubation in dark anoxic conditions (up to 24 h) in two secondary microalgae: the marine diatom Thalassiosira pseudonana and the excavate Euglena gracilis. RESULTS Both species showed sustained abilities to prevent over-reduction of photosynthetic electron carriers and to restore LEF. A high and transient CEF around PSI was also observed specifically in anoxic conditions at light onset in both species. In contrast, at variance with C. reinhardtii, no sustained hydrogenase activity was detected in anoxic conditions in both species. DISCUSSION Altogether our results suggest that another fermentative pathway might contribute, along with CEF around PSI, to restore photosynthetic activity in anoxic conditions in E. gracilis and T. pseudonana. We discuss the possible implication of the dissimilatory nitrate reduction to ammonium (DNRA) in T. pseudonana and the wax ester fermentation in E. gracilis.
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Affiliation(s)
- Gwenaëlle Gain
- InBioS – PhytoSYSTEMS, Laboratoire de Génétique et Physiologie des Microalgues, ULiège, Liège, Belgium
| | - Nicolas Berne
- InBioS – PhytoSYSTEMS, Laboratoire de Génétique et Physiologie des Microalgues, ULiège, Liège, Belgium
| | - Tom Feller
- InBioS – PhytoSYSTEMS, Laboratoire de Génétique et Physiologie des Microalgues, ULiège, Liège, Belgium
| | - Damien Godaux
- InBioS – PhytoSYSTEMS, Laboratoire de Génétique et Physiologie des Microalgues, ULiège, Liège, Belgium
| | - Ugo Cenci
- Unité de Glycobiologie Structurale et Fonctionnelle, Université de Lille, CNRS, UMR8576 – UGSF, Lille, France
| | - Pierre Cardol
- InBioS – PhytoSYSTEMS, Laboratoire de Génétique et Physiologie des Microalgues, ULiège, Liège, Belgium
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3
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Usai A, Pittman JK, Theodoropoulos C. A multiscale modelling approach for Haematococcus pluvialis cultivation under different environmental conditions. BIOTECHNOLOGY REPORTS 2022; 36:e00771. [PMID: 36345543 PMCID: PMC9636539 DOI: 10.1016/j.btre.2022.e00771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/16/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022]
Abstract
We develop a novel multiscale model for microalgal photoautotrophic growth. The model is segregated-structured type based on Population Balance Equations. We combine the model with cultivation experiments of Haematococcus pluvialis. We successfully predict cell number, average volume and density distribution dynamics. Model can accurately describe the nutrient depletion phase including cell lysis.
Haematococcus pluvialis can produce significant amounts of industrially important compounds belonging to lipids and starch classes, including various specific pigments such as β-carotene, lutein and astaxanthin, as well as lipids, carbohydrates and proteins. Their production can vary depending on environmental stress conditions like nutrient starvation. However, stress conditions lead also to undesired phenomena such as cell lysis, which is likely to be related to products loss. The microorganism develops towards smaller single cell volumes during the growth process, and eventually, more likely towards lysis when fission (i.e. cell division) slows down. The lysis process takes place simultaneously with nutrient depletion, so both growth and lysis are linked to the change of environmental conditions. In this work, we develop a novel multiscale segregated-structured model based on Population Balance Equations (PBEs) to describe the photoautotrophic growth of H.pluvialis, in particular cell growth, and lysis, making possible the description of the relationship between cell volume/transition, cell loss, and metabolic product availability. Cell volume is the internal coordinate of the population balance model, and its link with intrinsic concentrations is also presented. The model parameters are fitted against experimental data, extensive sensitivity analysis is performed and the model predictive capabilities are tested in terms of cell density distributions, as well as 0th and 1st order moments.
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Affiliation(s)
- Alessandro Usai
- Department of Chemical Engineering, University of Manchester, M13 9PL, UK,Biochemical and Bioprocess Engineering Group, University of Manchester, M13 9PL, UK
| | - Jon K. Pittman
- Department of Earth and Environmental Sciences, University of Manchester, M13 9PL, UK
| | - Constantinos Theodoropoulos
- Department of Chemical Engineering, University of Manchester, M13 9PL, UK,Biochemical and Bioprocess Engineering Group, University of Manchester, M13 9PL, UK,Corresponding author at: Department of Chemical Engineering, University of Manchester, M13 9PL, UK.
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Fuchsman CA, Cherubini L, Hays MD. An analysis of protists in Pacific oxygen deficient zones: implications for Prochlorococcus and N 2 -producing bacteria. Environ Microbiol 2022; 24:1790-1804. [PMID: 34995411 DOI: 10.1111/1462-2920.15893] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 12/27/2021] [Accepted: 12/29/2021] [Indexed: 11/26/2022]
Abstract
Ocean oxygen deficient zones (ODZs) host 30%-50% of marine N2 production. Cyanobacteria photosynthesizing in the ODZ create a secondary chlorophyll maximum and provide organic matter to N2 -producing bacteria. This chlorophyll maximum is thought to occur due to reduced grazing in anoxic waters. We first examine ODZ protists with long amplicon reads. We then use non-primer-based methods to examine the composition and relative abundance of protists in metagenomes from the Eastern Tropical North and South Pacific ODZs and compare these data to the oxic Hawaii Ocean Time-series (HOT) in the North Pacific. We identify and quantify protists in proportion to the total microbial community. From metagenomic data, we see a large drop in abundance of fungi and protists such as choanoflagellates, radiolarians, cercozoa and ciliates in the ODZs but not in the oxic mesopelagic at HOT. Diplonemid euglenozoa were the only protists that increased in the ODZ. Dinoflagellates and foraminifera reads were also present in the ODZ though less abundant compared to oxic waters. Denitrification has been found in foraminifera but not yet in dinoflagellates. DNA techniques cannot separate dinoflagellate cells and cysts. Metagenomic analysis found taxonomic groups missed by amplicon sequencing and identified trends in abundance.
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Affiliation(s)
- Clara A Fuchsman
- University of Maryland Center for Environmental Science Horn Point Laboratory, Cambridge, MD, 21613, USA
| | - Luca Cherubini
- Maryland Sea Grant College, College Park, MD, 20740, USA
| | - Matthew D Hays
- University of Maryland Center for Environmental Science Horn Point Laboratory, Cambridge, MD, 21613, USA
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5
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Chai X, Li X, Hii KS, Zhang Q, Deng Q, Wan L, Zheng L, Lim PT, Tan SN, Mohd-Din M, Song C, Song L, Zhou Y, Cao X. Blooms of diatom and dinoflagellate associated with nutrient imbalance driven by cycling of nitrogen and phosphorus in anaerobic sediments in Johor Strait (Malaysia). MARINE ENVIRONMENTAL RESEARCH 2021; 169:105398. [PMID: 34171592 DOI: 10.1016/j.marenvres.2021.105398] [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: 12/17/2020] [Revised: 06/13/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
Coastal eutrophication is one of the pivotal factors driving occurrence of harmful algal blooms (HABs), whose underlying mechanism remained unclear. To better understand the nutrient regime triggering HABs and their formation process, the phytoplankton composition and its response to varying nitrogen (N) and phosphorus (P), physio-chemical parameters in water and sediment in Johor Strait in March 2019 were analyzed. Surface and sub-surface HABs were observed with the main causative species of Skeletonema, Chaetoceros and Karlodinium. The ecophysiological responses of Skeletonema to the low ambient N/P ratio such as secreting alkaline phosphatase, regulating cell morphology (volume; surface area/volume ratio) might play an important role in dominating the community. Anaerobic sediment iron-bound P release and simultaneous N removal by denitrification and anammox, shaped the stoichiometry of N and P in water column. The decrease of N/P ratio might shift the phytoplankton community into the dominance of HABs causative diatoms and dinoflagellates.
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Affiliation(s)
- Xiaojie Chai
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China; University of Chinese Academy of Sciences, Beijing, 100039, PR China.
| | - Xiaowen Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
| | - Kieng Soon Hii
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, 16310, Kelantan, Malaysia.
| | - Qi Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
| | - Qinghui Deng
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China; University of Chinese Academy of Sciences, Beijing, 100039, PR China.
| | - Lingling Wan
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
| | - Lingling Zheng
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
| | - Po Teen Lim
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, 16310, Kelantan, Malaysia.
| | - Suh Nih Tan
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, 16310, Kelantan, Malaysia; Institute of Oceanography and Environment, University of Terengganu Malaysia, Malaysia; China-ASEAN College of Marine Sciences, Xiamen University Malaysia, Sepang, 43900, Selangor Malaysia.
| | - Monaliza Mohd-Din
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok, 16310, Kelantan, Malaysia.
| | - Chunlei Song
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
| | - Lirong Song
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
| | - Yiyong Zhou
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
| | - Xiuyun Cao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, PR China.
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Occurrence, Evolution and Specificities of Iron-Sulfur Proteins and Maturation Factors in Chloroplasts from Algae. Int J Mol Sci 2021; 22:ijms22063175. [PMID: 33804694 PMCID: PMC8003979 DOI: 10.3390/ijms22063175] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/25/2021] [Accepted: 03/17/2021] [Indexed: 01/08/2023] Open
Abstract
Iron-containing proteins, including iron-sulfur (Fe-S) proteins, are essential for numerous electron transfer and metabolic reactions. They are present in most subcellular compartments. In plastids, in addition to sustaining the linear and cyclic photosynthetic electron transfer chains, Fe-S proteins participate in carbon, nitrogen, and sulfur assimilation, tetrapyrrole and isoprenoid metabolism, and lipoic acid and thiamine synthesis. The synthesis of Fe-S clusters, their trafficking, and their insertion into chloroplastic proteins necessitate the so-called sulfur mobilization (SUF) protein machinery. In the first part, we describe the molecular mechanisms that allow Fe-S cluster synthesis and insertion into acceptor proteins by the SUF machinery and analyze the occurrence of the SUF components in microalgae, focusing in particular on the green alga Chlamydomonas reinhardtii. In the second part, we describe chloroplastic Fe-S protein-dependent pathways that are specific to Chlamydomonas or for which Chlamydomonas presents specificities compared to terrestrial plants, putting notable emphasis on the contribution of Fe-S proteins to chlorophyll synthesis in the dark and to the fermentative metabolism. The occurrence and evolutionary conservation of these enzymes and pathways have been analyzed in all supergroups of microalgae performing oxygenic photosynthesis.
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7
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Popovich CA, Faraoni MB, Sequeira A, Daglio Y, Martín LA, Martínez AM, Damiani MC, Matulewicz MC, Leonardi PI. Potential of the marine diatom Halamphora coffeaeformis to simultaneously produce omega-3 fatty acids, chrysolaminarin and fucoxanthin in a raceway pond. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.102030] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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8
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Montgomery MT, Boyd TJ, Hall NS, Paerl HW, Osburn CL. Ecosystem Capacity for Microbial Biodegradation of Munitions Compounds and Phenanthrene in Three Coastal Waterways in North Carolina, United States. ACS OMEGA 2020; 5:7326-7341. [PMID: 32280874 PMCID: PMC7144167 DOI: 10.1021/acsomega.9b04188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 02/18/2020] [Indexed: 06/11/2023]
Abstract
Munitions compounds (i.e., 2,4,6-trinitrotoluene (TNT), octahy-dro-1,3,5,7-tetranitro-1,3,5,7-tetrazocin (HMX), and hexadydro-1,3,5-trinitro-1,3,5-triazin (RDX), also called energetics) were originally believed to be recalcitrant to microbial biodegradation based on historical groundwater chemical attenuation data and laboratory culture work. More recently, it has been established that natural bacterial assemblages in coastal waters and sediment can rapidly metabolize these organic nitrogen sources and even incorporate their carbon and nitrogen into bacterial biomass. Here, we report on the capacity of natural microbial assemblages in three coastal North Carolina (United States) estuaries to metabolize energetics and phenanthrene (PHE), a proxy for terrestrial aromatic compounds. Microbial assemblages generally had the highest ecosystem capacity (mass of the compound mineralized per average estuarine residence time) for HMX (21-5463 kg) > RDX (1.4-5821 kg) ≫ PHE (0.29-660 kg) > TNT (0.25-451 kg). Increasing antecedent precipitation tended to decrease the ecosystem capacity to mineralize TNT in the Newport River Estuary, and PHE and TNT mineralization were often highest with increasing salinity. There was some evidence from the New River Estuary that increased N-demand (due to a phytoplankton bloom) is associated with increased energetic mineralization rates. Using this type of analysis to determine the ecosystem capacity to metabolize energetics can explain why these compounds are rarely detected in seawater and marine sediment, despite the known presence of unexploded ordnance or recent use in military training exercises. Overall, measuring the ecosystem capacity may help predict the effects of climate change (warming and altered precipitation patterns) and other perturbations on exotic compound fate and transport within ecosystems and provide critical information for managers and decision-makers to develop management strategies based on these changes.
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Affiliation(s)
- Michael T. Montgomery
- Chemistry
Division, Naval Research Laboratory, 4555 Overlook Avenue Southwest, Washington, District of Columbia 20375, United States
| | - Thomas J. Boyd
- Chemistry
Division, Naval Research Laboratory, 4555 Overlook Avenue Southwest, Washington, District of Columbia 20375, United States
| | - Nathan S. Hall
- Institute
of Marine Sciences, University of North
Carolina, Morehead City, North Carolina 28557, United States
| | - Hans W. Paerl
- Institute
of Marine Sciences, University of North
Carolina, Morehead City, North Carolina 28557, United States
| | - Christopher L. Osburn
- Department
of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina 27695, United States
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9
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Diatom-Derived Polyunsaturated Aldehydes Are Unlikely to Influence the Microbiota Composition of Laboratory-Cultured Diatoms. Life (Basel) 2020; 10:life10030029. [PMID: 32213870 PMCID: PMC7151586 DOI: 10.3390/life10030029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 02/18/2020] [Accepted: 03/20/2020] [Indexed: 01/30/2023] Open
Abstract
Diatom-derived oxylipins, including polyunsaturated aldehydes (PUA), are considered to have infochemical, allelochemical and bacteriostatic properties, with plausible roles as grazing deterrents and regulators of inter- and intraspecific competition. However, the extent and mechanisms of how PUA influence diatom–bacteria interactions remain unresolved. In this study, impacts on the diversity of the associated bacterial communities (microbiota) of two contrasting Skeletonema marinoi strains (a PUA and a non-PUA producer) were investigated under three nitrate conditions in batch culture. Further, the response of the culture microbiota was studied when spiked with PUA at ecologically relevant concentrations (86nM octadienal and 290nM heptadienal). Of the 741 identified OTUs, Proteobacteria was the most abundant phylum (62.10%), followed by Bacteroidetes (12.33%) and Firmicutes (6.11%). Escherichia/Shigella were the most abundant genera for all treatments. Similar communities were present in both spiked and non-spiked cultures suggesting they can tolerate PUA exposure at realistic concentrations. This study suggests that PUA are not major drivers of diatom–bacteria interactions in laboratory cultures.
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10
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Wang H, Chen F, Mi T, Liu Q, Yu Z, Zhen Y. Responses of Marine Diatom Skeletonema marinoi to Nutrient Deficiency: Programmed Cell Death. Appl Environ Microbiol 2020; 86:e02460-19. [PMID: 31757826 PMCID: PMC6974647 DOI: 10.1128/aem.02460-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 11/15/2019] [Indexed: 11/20/2022] Open
Abstract
Diatoms are important phytoplankton and contribute greatly to the primary productivity of marine ecosystems. Despite the ecological significance of diatoms and the importance of programmed cell death (PCD) in the fluctuation of diatom populations, little is known about the molecular mechanisms of PCD triggered by different nutrient stresses. Here we describe the physiological, morphological, biochemical, and molecular changes in response to low levels of nutrients in the ubiquitous diatom Skeletonema marinoi The levels of gene expression involved in oxidation resistance and PCD strongly increased upon nitrogen (N) or phosphorus (P) starvation. The enzymatic activity of caspase 3-like protein also increased. Differences in mRNA levels and protein activities were observed between the low-N and low-P treatments, suggesting that PCD could have a differential response to different nutrient stresses. When cultures were replete with N or P, the growth inhibition stopped. Meanwhile, the enzymatic activity of caspase 3-like protein and the number of cells with damaged membranes decreased. These results suggest that PCD is an important cell fate decision mechanism in the marine diatom S. marinoi Our results provide important insight into how diatoms adjust phenotypic and genotypic features of their cell-regulated death programs when stressed by nutrient limitations. Overall, this study could allow us to better understand the molecular mechanism behind the formation and termination of diatom blooms in the marine environment.IMPORTANCE Our study showed how the ubiquitous diatom S. marinoi responded to different nutrient limitations with PCD in terms of physiological, morphological, biochemical, and molecular characteristics. Some PCD-related genes (PDCD4, GOX, and HSP90) induced by N deficiency were relatively upregulated compared to those induced by P deficiency. In contrast, the expression of the TSG101 gene in S. marinoi showed a clear and constant increase during P limitation compared to N limitation. These findings suggest that PCD is a complex mechanism involving several different proteins. The systematic mRNA level investigations provide new insight into understanding the oxidative stress- and cell death-related functional genes of diatoms involved in the response to nutrient fluctuations (N or P stress) in the marine environment.
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Affiliation(s)
- Hualong Wang
- College of Marine Life Science, Ocean University of China, Qingdao, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, USA
| | - Feng Chen
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, USA
| | - Tiezhu Mi
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, China
| | - Qian Liu
- College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Zhigang Yu
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Chemical Theory and Technology, Ministry of Education, Qingdao, China
| | - Yu Zhen
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, China
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11
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Stief P, Lundgaard ASB, Treusch AH, Thamdrup B, Grossart HP, Glud RN. Freshwater copepod carcasses as pelagic microsites of dissimilatory nitrate reduction to ammonium. FEMS Microbiol Ecol 2019; 94:5061118. [PMID: 30060193 PMCID: PMC6084575 DOI: 10.1093/femsec/fiy144] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 07/26/2018] [Indexed: 11/13/2022] Open
Abstract
A considerable fraction of freshwater zooplankton was recently found to consist of dead specimens that sink to the lake bottom. Such carcasses host intense microbial activities that may promote oxygen depletion at the microscale. Therefore, we tested the hypothesis that sinking zooplankton carcasses are microsites of anaerobic nitrogen cycling that contribute to pelagic fixed-nitrogen loss even in the presence of ambient oxygen. Incubation experiments were performed with the ubiquitous copepods Eudiaptomus sp. and Megacyclops gigas at different ambient oxygen levels that sinking carcasses encounter during their descent in stratified lakes. 15N-stable-isotope incubations revealed intense carcass-associated anaerobic nitrogen cycling only at low ambient oxygen levels (<25% air saturation). Dissimilatory nitrate reduction to ammonium (DNRA) dominated over denitrification and thus the potential for fixed-nitrogen loss was low. Consistent with this partitioning of anaerobic nitrogen cycling, the relative abundance of the carcass-associated marker gene for DNRA (nrfA) was ∼20–400 times higher than that for denitrification (nirS). Additionally, the relative nrfA and nirS abundances were ∼90–180 times higher on copepod carcasses than in lake water. This functional distinctiveness of carcass-associated bacterial communities was further substantiated by 16S rDNA-based fingerprinting. We conclude that the unique bacterial communities and microenvironments provided by zooplankton carcasses influence pelagic nitrogen cycling in lakes, but mainly at seasonally low ambient O2 levels in the bottom water.
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Affiliation(s)
- Peter Stief
- Department of Biology, Nordcee, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Ann Sofie Birch Lundgaard
- Department of Biology, Nordcee, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Alexander H Treusch
- Department of Biology, Nordcee, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Bo Thamdrup
- Department of Biology, Nordcee, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Hans-Peter Grossart
- Institute of Freshwater Ecology and Inland Fisheries, Department of Limnology of Stratified Lakes, Alte Fischerhütte 2, 16775 Neuglobsow, Germany
| | - Ronnie N Glud
- Department of Biology, Nordcee, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.,Department of Ocean and Environmental Sciences, Tokyo University of Marine Science and Technology, 108-8477 Tokyo, Japan
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12
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Olofsson M, Kourtchenko O, Zetsche E, Marchant HK, Whitehouse MJ, Godhe A, Ploug H. High single-cell diversity in carbon and nitrogen assimilations by a chain-forming diatom across a century. Environ Microbiol 2019; 21:142-151. [PMID: 30277299 PMCID: PMC7379523 DOI: 10.1111/1462-2920.14434] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 09/26/2018] [Indexed: 11/30/2022]
Abstract
Almost a century ago Redfield discovered a relatively constant ratio between carbon, nitrogen and phosphorus in particulate organic matter and nitrogen and phosphorus of dissolved nutrients in seawater. Since then, the riverine export of nitrogen to the ocean has increased 20 fold. High abundance of resting stages in sediment layers dated more than a century back indicate that the common planktonic diatom Skeletonema marinoi has endured this eutrophication. We germinated unique genotypes from resting stages originating from isotope-dated sediment layers (15 and 80 years old) in a eutrophied fjord. Using secondary ion mass spectrometry (SIMS) combined with stable isotopic tracers, we show that the cell-specific carbon and nitrogen assimilation rates vary by an order of magnitude on a single-cell level but are significantly correlated during the exponential growth phase, resulting in constant assimilation quota in cells with identical genotypes. The assimilation quota varies largely between different clones independent of age. We hypothesize that the success of S. marinoi in coastal waters may be explained by its high diversity of nutrient demand not only at a clone-specific level but also at the single-cell level, whereby the population can sustain and adapt to dynamic nutrient conditions in the environment.
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Affiliation(s)
- Malin Olofsson
- Department of Marine SciencesUniversity of GothenburgBox 461, 405 30GothenburgSweden
| | - Olga Kourtchenko
- Department of Marine SciencesUniversity of GothenburgBox 461, 405 30GothenburgSweden
| | - Eva‐Maria Zetsche
- Department of Marine SciencesUniversity of GothenburgBox 461, 405 30GothenburgSweden
| | - Hannah K. Marchant
- Max Planck Institute for Marine MicrobiologyCelsiusstrasse 1, 28359BremenGermany
| | | | - Anna Godhe
- Department of Marine SciencesUniversity of GothenburgBox 461, 405 30GothenburgSweden
| | - Helle Ploug
- Department of Marine SciencesUniversity of GothenburgBox 461, 405 30GothenburgSweden
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13
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Netzer R, Henry IA, Ribicic D, Wibberg D, Brönner U, Brakstad OG. Petroleum hydrocarbon and microbial community structure successions in marine oil-related aggregates associated with diatoms relevant for Arctic conditions. MARINE POLLUTION BULLETIN 2018; 135:759-768. [PMID: 30301095 DOI: 10.1016/j.marpolbul.2018.07.074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/24/2018] [Accepted: 07/26/2018] [Indexed: 06/08/2023]
Abstract
Oil-related aggregates (ORAs) may contribute to the fate of oil spilled offshore. However, our understanding about the impact of diatoms and associated bacteria involved in the formation of ORAs and the fate of oil compounds in these aggregates is still limited. We investigated these processes in microcosm experiments with defined oil dispersions in seawater at 5 °C, employing the Arctic diatom Fragilariopsis cylindrus and its associated bacterial assemblage to promote ORA formation. Accumulation of oil compounds, as well as biodegradation of naphthalenes in ORAs and corresponding water phases, was enhanced in the presence of diatoms. Interestingly, the genus Nonlabens was predominating the bacterial communities in diatom-supplemented microcosms, while this genus was not abundant in other samples. This work elucidates the relevance of diatom biomass for the formation of ORAs, microbial community structures and biodegradation processes in chemically dispersed oil at low temperatures relevant for Arctic conditions.
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Affiliation(s)
- Roman Netzer
- SINTEF Ocean, Brattørkaia 17C, 7010 Trondheim, Norway.
| | | | - Deni Ribicic
- SINTEF Ocean, Brattørkaia 17C, 7010 Trondheim, Norway
| | - Daniel Wibberg
- Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Ute Brönner
- SINTEF Ocean, Brattørkaia 17C, 7010 Trondheim, Norway
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14
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Arias-Andres M, Kettner MT, Miki T, Grossart HP. Microplastics: New substrates for heterotrophic activity contribute to altering organic matter cycles in aquatic ecosystems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 635:1152-1159. [PMID: 29710570 DOI: 10.1016/j.scitotenv.2018.04.199] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/15/2018] [Accepted: 04/15/2018] [Indexed: 05/21/2023]
Abstract
Heterotrophic microbes with the capability to process considerable amounts of organic matter can colonize microplastic particles (MP) in aquatic ecosystems. Weather colonization of microorganisms on MP will alter ecological niche and functioning of microbial communities remains still unanswered. Therefore, we compared the functional diversity of biofilms on microplastics when incubated in three lakes in northeastern Germany differing in trophy and limnological features. For all lakes, we compared heterotrophic activities of MP biofilms with those of microorganisms in the surrounding water by using Biolog® EcoPlates and assessed their oxygen consumption in microcosm assays with and without MP. The present study found that the total biofilm biomass was higher in the oligo-mesotrophic and dystrophic lakes than in the eutrophic lake. In all lakes, functional diversity profiles of MP biofilms consistently differed from those in the surrounding water. However, solely in the oligo-mesotrophic lake MP biofilms had a higher functional richness compared to the ambient water. These results demonstrate that the functionality and hence the ecological role of MP-associated microbial communities are context-dependent, i.e. different environments lead to substantial changes in biomass build up and heterotrophic activities of MP biofilms. We propose that MP surfaces act as new niches for aquatic microorganisms and that the constantly increasing MP pollution has the potential to globally impact carbon dynamics of pelagic environments by altering heterotrophic activities.
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Affiliation(s)
- Maria Arias-Andres
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Dept. Experimental Limnology, Alte Fischerhuette 2, D-16775 Stechlin, Germany; Potsdam University, Inst. of Biochemistry and Biology, Maulbeerallee 2, D-14469 Potsdam, Germany; Central American Institute for Studies on Toxic Substances (IRET), Universidad Nacional, Campus Omar Dengo, P.O. Box 86-3000, Heredia, Costa Rica
| | - Marie Therese Kettner
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Dept. Experimental Limnology, Alte Fischerhuette 2, D-16775 Stechlin, Germany; Potsdam University, Inst. of Biochemistry and Biology, Maulbeerallee 2, D-14469 Potsdam, Germany
| | - Takeshi Miki
- Institute of Oceanography, National Taiwan University, No. 1 Sec. 4 Roosevelt Rd, Taipei 10617, Taiwan; Research Center for Environmental Changes, Academia Sinica, 128 Academia Road, Section 2, Nankang, 11529 Taipei, Taiwan
| | - Hans-Peter Grossart
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Dept. Experimental Limnology, Alte Fischerhuette 2, D-16775 Stechlin, Germany; Potsdam University, Inst. of Biochemistry and Biology, Maulbeerallee 2, D-14469 Potsdam, Germany.
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15
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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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16
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Gao G, Xia J, Yu J, Zeng X. Physiological response of a red tide alga (Skeletonema costatum) to nitrate enrichment, with special reference to inorganic carbon acquisition. MARINE ENVIRONMENTAL RESEARCH 2018; 133:15-23. [PMID: 29174425 DOI: 10.1016/j.marenvres.2017.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 11/11/2017] [Accepted: 11/12/2017] [Indexed: 06/07/2023]
Abstract
A classical red tide alga Skeletonema costatum was cultured under various nitrate levels to investigate its physiological response to nitrate enrichment combined with CO2 limitation. The higher nitrate levels increased content of photosynthetic pigments (Chl a and Chl c), electron transport rate in photosystem II, photosynthetic O2 evolution, and thus growth rate in S. costatum. On the other hand, the lower CO2 levels (3.5-4.4 μmol kg-1 seawater) and higher pH (8.56-8.63) values in seawater were observed under higher nitrate conditions. Redox activity of plasma membrane and carbonic anhydrase in S. costatum was enhanced to address the reduced CO2 level at higher nitrate levels. In addition, the pH compensation point was enhanced and direct HCO3- use was induced at higher nitrate levels. These findings indicate that nitrate enrichment would stimulate the breakout of S. costatum dominated red tides via enhancing its photosynthetic performances, and maintain a quick growth rate under CO2 limitation conditions through improving its inorganic carbon acquisition capability. Our study sheds light on the mechanisms of S. costatum defeating CO2 limitation during algal bloom.
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Affiliation(s)
- Guang Gao
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; Marine Resources Development Institute of Jiangsu, Huaihai Institute of Technology, Lianyungang 222005, China
| | - Jianrong Xia
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China.
| | - Jinlan Yu
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Xiaopeng Zeng
- School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
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17
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Marzocchi U, Thamdrup B, Stief P, Glud RN. Effect of settled diatom-aggregates on benthic nitrogen cycling. LIMNOLOGY AND OCEANOGRAPHY 2018; 63:431-444. [PMID: 29456269 PMCID: PMC5812115 DOI: 10.1002/lno.10641] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 06/28/2017] [Accepted: 06/29/2017] [Indexed: 06/08/2023]
Abstract
The marine sediment hosts a mosaic of microhabitats. Recently it has been demonstrated that the settlement of phycodetrital aggregates can induce local changes in the benthic O2 distribution due to confined enrichment of organic material and alteration of the diffusional transport. Here, we show how this microscale O2 shift substantially affects benthic nitrogen cycling. In sediment incubations, the settlement of diatom-aggregates markedly enhanced benthic O2 and NO3- consumption and stimulated NO2- and NH4+ production. Oxygen microprofiles revealed the rapid development of anoxic niches within and underneath the aggregates. During 120 h following the settling of the aggregates, denitrification of NO3- from the overlying water increased from 13.5 μmol m-2 h-1 to 24.3 μmol m-2 h-1, as quantified by 15N enrichment experiment. Simultaneously, N2 production from coupled nitrification-denitrification decreased from 33.4 μmol m-2 h-1 to 25.9 μmol m-2 h-1, probably due to temporary inhibition of the benthic nitrifying community. The two effects were of similar magnitude and left the total N2 production almost unaltered. At the aggregate surface, nitrification was, conversely, very efficient in oxidizing NH4+ liberated by mineralization of the aggregates. The produced NO3- was preferentially released into the overlying water and only a minor fraction contributed to denitrification activity. Overall, our data indicate that the abrupt change in O2 microdistribution caused by aggregates stimulates denitrification of NO3- from the overlying water, and loosens the coupling between benthic nitrification and denitrification both in time and space. The study contributes to expanding the conceptual and quantitative understanding of how nitrogen cycling is regulated in dynamic benthic environments.
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Affiliation(s)
- Ugo Marzocchi
- Department of Biology and Nordic Center for Earth Evolution (NordCEE)University of Southern Denmark, Odense MDenmark
- Department of AnalyticalEnvironmental and Geo‐Chemistry, Vrije Universiteit Brussel (VUB)BrusselsBelgium
- Center for Geomicrobiology and Section for Microbiology, Aarhus UniversityAarhusDenmark
| | - Bo Thamdrup
- Department of Biology and Nordic Center for Earth Evolution (NordCEE)University of Southern Denmark, Odense MDenmark
| | - Peter Stief
- Department of Biology and Nordic Center for Earth Evolution (NordCEE)University of Southern Denmark, Odense MDenmark
| | - Ronnie N. Glud
- Department of Biology and Nordic Center for Earth Evolution (NordCEE)University of Southern Denmark, Odense MDenmark
- Scottish Association for Marine Science, ObanUnited Kingdom
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18
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Olivares-Rubio HF, Salazar-Coria L, Nájera-Martínez M, Godínez-Ortega JL, Vega-López A. Lipid metabolism and pro-oxidant/antioxidant balance of Halamphora oceanica from the Gulf of Mexico exposed to water accommodated fraction of Maya crude oil. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 147:840-851. [PMID: 28968937 DOI: 10.1016/j.ecoenv.2017.09.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 06/07/2023]
Abstract
Diatoms play key roles in primary production and carbon fixation at a global scale and in some cases these species live on marine ecosystems impacted by crude oil (CO) spills. Halamphora oceanica, a new diatom species from the Southwest of the Gulf of Mexico was isolated and cultured in the laboratory and was exposed to water accommodated fraction (WAF) of different Maya CO loads at 0.01, 0.1, 1 and 10g/L by 96h. A battery of biomarkers involved in oxidative stress (O2•, H2O2, TBARS, ROOH, RC=O, SOD, CAT, GPx), biotransformation and conjugation (total CYP450 activity and GST) moreover fatty acid (FA) metabolism (FA levels, fatty-acid synthase and acyl-CoA oxidase) were measured. Obtained results suggest that increases of PAHs in the medium (below to EC50) acts as external forces able to turn-on regulatory mechanisms on H. oceanica involved in both, on the PAHs uptake and changing its aerobic metabolism to anaerobic metabolism. However, the growth of this microalgae species evaluated as chlorophyll "a" and pheophytin levels increased as the WAF concentration indicating that PAHs and other hydrosoluble hydrocarbons were used as carbon and energy sources by unidentified enzymes not evaluated in the current study. Our hypothesis was also corroborated by IBRv2. In the current study, we suppose the change from aerobic to anaerobic metabolism as a strategy for Halamphora oceanica survival exposed to petroleum hydrocarbons.
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Affiliation(s)
- Hugo F Olivares-Rubio
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Laboratorio de Toxicología Ambiental. Av. Wilfrido Massieu s/n, Unidad Profesional Zacatenco, México D.F. CP 07738, Mexico
| | - Lucía Salazar-Coria
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Laboratorio de Toxicología Ambiental. Av. Wilfrido Massieu s/n, Unidad Profesional Zacatenco, México D.F. CP 07738, Mexico
| | - Minerva Nájera-Martínez
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Laboratorio de Toxicología Ambiental. Av. Wilfrido Massieu s/n, Unidad Profesional Zacatenco, México D.F. CP 07738, Mexico
| | - José Luis Godínez-Ortega
- Universidad Nacional Autónoma de México, Instituto de Biología, Apdo. postal 70-233, 04510 México D.F., Mexico
| | - Armando Vega-López
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Laboratorio de Toxicología Ambiental. Av. Wilfrido Massieu s/n, Unidad Profesional Zacatenco, México D.F. CP 07738, Mexico.
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19
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Cavan EL, Trimmer M, Shelley F, Sanders R. Remineralization of particulate organic carbon in an ocean oxygen minimum zone. Nat Commun 2017; 8:14847. [PMID: 28322218 PMCID: PMC5364423 DOI: 10.1038/ncomms14847] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 02/06/2017] [Indexed: 12/01/2022] Open
Abstract
Biological oceanic processes, principally the surface production, sinking and interior remineralization of organic particles, keep atmospheric CO2 lower than if the ocean was abiotic. The remineralization length scale (RLS, the vertical distance over which organic particle flux declines by 63%, affected by particle respiration, fragmentation and sinking rates) controls the size of this effect and is anomalously high in oxygen minimum zones (OMZ). Here we show in the Eastern Tropical North Pacific OMZ 70% of POC remineralization is due to microbial respiration, indicating that the high RLS is the result of lower particle fragmentation by zooplankton, likely due to the almost complete absence of zooplankton particle interactions in OMZ waters. Hence, the sensitivity of zooplankton to ocean oxygen concentrations can have direct implications for atmospheric carbon sequestration. Future expansion of OMZs is likely to increase biological ocean carbon storage and act as a negative feedback on climate change. The downward transfer of organic carbon from the surface to the deep ocean is increased in oxygen minimum zones relative to oxic waters. Here, the authors show reduced interactions of zooplankton with sinking particles owing to low oxygen are likely the primary reason for the observed high transfer of carbon.
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Affiliation(s)
- E L Cavan
- National Oceanography Centre, European Way, Southampton SO14 3ZH, UK.,University of Southampton, National Oceanography Centre, European Way, Southampton SO14 3ZH, UK
| | - M Trimmer
- Queen Mary University London, Mile End Road, London E1 4NS, UK
| | - F Shelley
- Queen Mary University London, Mile End Road, London E1 4NS, UK
| | - R Sanders
- National Oceanography Centre, European Way, Southampton SO14 3ZH, UK
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