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Hernández-León S. The biological carbon pump, diel vertical migration, and carbon dioxide removal. iScience 2023; 26:107835. [PMID: 38026165 PMCID: PMC10651677 DOI: 10.1016/j.isci.2023.107835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023] Open
Abstract
Carbon dioxide is increasing in the atmosphere promoting the faster environmental change of the Earth's recent history. Several marine carbon dioxide removal (mCDR) technologies were proposed to slow down CO2 in the atmosphere. Technologies now under experimentation are related to the increase in gravitational flux. Other mechanisms such as active flux, the transport performed by diel vertical migrants (DVMs) were not considered. We review the effect of DVMs in the epipelagic realm and the top-down promoted by these organisms upon zooplankton and microzooplankton, and their variability due to lunar cycles. A night source of weak light will increase epipelagic zooplankton biomass due to DVMs avoidance from the upper layers to escape predation, promoting DVMs to export this biomass by active flux once the illumination ceases. This mCDR method should be tested in the field as it will increase the efficiency of the biological carbon pump in the ocean.
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Affiliation(s)
- Santiago Hernández-León
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, Unidad Asociada ULPGC-CSIC, Campus de Taliarte, Telde, 35214 Gran Canaria, Canary Islands, Spain
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2
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Lennox RJ, Brownscombe JW, Darimont C, Horodysky A, Levi T, Raby GD, Cooke SJ. The roles of humans and apex predators in sustaining ecosystem structure and function: Contrast, complementarity and coexistence. PEOPLE AND NATURE 2022. [DOI: 10.1002/pan3.10385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Robert J. Lennox
- Laboratory for Freshwater Ecology and Inland Fisheries at NORCE Norwegian Research Center Bergen Norway
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology Carleton University Ottawa Ontario Canada
- Norwegian Institute for Nature Research (NINA) Trondheim Norway
| | - Jacob W. Brownscombe
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology Carleton University Ottawa Ontario Canada
- Great Lakes Laboratory for Fisheries and Aquatic Sciences Fisheries and Oceans Canada Burlington Ontario Canada
| | | | - Andrij Horodysky
- Department of Marine and Environmental Science Hampton University Hampton Virginia USA
| | - Taal Levi
- Department of Fisheries and Wildlife Oregon State University Corvallis Oregon USA
| | - Graham D. Raby
- Department of Biology Trent University Peterborough Ontario Canada
| | - Steven J. Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology Carleton University Ottawa Ontario Canada
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Huang J, Jones A, Waite TD, Chen Y, Huang X, Rosso KM, Kappler A, Mansor M, Tratnyek PG, Zhang H. Fe(II) Redox Chemistry in the Environment. Chem Rev 2021; 121:8161-8233. [PMID: 34143612 DOI: 10.1021/acs.chemrev.0c01286] [Citation(s) in RCA: 139] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Iron (Fe) is the fourth most abundant element in the earth's crust and plays important roles in both biological and chemical processes. The redox reactivity of various Fe(II) forms has gained increasing attention over recent decades in the areas of (bio) geochemistry, environmental chemistry and engineering, and material sciences. The goal of this paper is to review these recent advances and the current state of knowledge of Fe(II) redox chemistry in the environment. Specifically, this comprehensive review focuses on the redox reactivity of four types of Fe(II) species including aqueous Fe(II), Fe(II) complexed with ligands, minerals bearing structural Fe(II), and sorbed Fe(II) on mineral oxide surfaces. The formation pathways, factors governing the reactivity, insights into potential mechanisms, reactivity comparison, and characterization techniques are discussed with reference to the most recent breakthroughs in this field where possible. We also cover the roles of these Fe(II) species in environmental applications of zerovalent iron, microbial processes, biogeochemical cycling of carbon and nutrients, and their abiotic oxidation related processes in natural and engineered systems.
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Affiliation(s)
- Jianzhi Huang
- Department of Civil and Environmental Engineering, Case Western Reserve University, 2104 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Adele Jones
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Yiling Chen
- Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Xiaopeng Huang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Kevin M Rosso
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, 72076 Tuebingen, Germany
| | - Muammar Mansor
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, 72076 Tuebingen, Germany
| | - Paul G Tratnyek
- School of Public Health, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Huichun Zhang
- Department of Civil and Environmental Engineering, Case Western Reserve University, 2104 Adelbert Road, Cleveland, Ohio 44106, United States
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Roy AS, Woehle C, LaRoche J. The Transfer of the Ferredoxin Gene From the Chloroplast to the Nuclear Genome Is Ancient Within the Paraphyletic Genus Thalassiosira. Front Microbiol 2020; 11:523689. [PMID: 33123095 PMCID: PMC7566914 DOI: 10.3389/fmicb.2020.523689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 09/07/2020] [Indexed: 11/24/2022] Open
Abstract
Ferredoxins are iron–sulfur proteins essential for a wide range of organisms because they are an electron transfer mediator involved in multiple metabolic pathways. In phytoplankton, these proteins are active in the mature chloroplasts, but the petF gene, encoding for ferredoxin, has been found either to be in the chloroplast genome or transferred to the nuclear genome as observed in the green algae and higher plant lineage. We experimentally determined the location of the petF gene in 12 strains of Thalassiosira covering three species using DNA sequencing and qPCR assays. The results showed that petF gene is located in the nuclear genome of all confirmed Thalassiosira oceanica strains (CCMP0999, 1001, 1005, and 1006) tested. In contrast, all Thalassiosira pseudonana (CCMP1012, 1013, 1014, and 1335) and Thalassiosira weissflogii (CCMP1010, 1049, and 1052) strains studied retained the gene in the chloroplast genome, as generally observed for Bacillariophyceae. Our evolutionary analyses further extend the dataset on the localization of the petF gene in the Thalassiosirales. The realization that the petF gene is nuclear-encoded in the Skeletonema genus allowed us to trace the petF gene transfer back to a single event that occurred within the paraphyletic genus Thalassiosira. Phylogenetic analyses revealed the need to reassess the taxonomic assignment of the Thalassiosira strain CCMP1616, since the genes used in our study did not cluster within the T. oceanica lineage. Our results suggest that this strains’ diversification occurred prior to the ferredoxin gene transfer event. The functional transfer of petF genes provides insight into the evolutionary processes leading to chloroplast genome reduction and suggests ecological adaptation as a driving force for such chloroplast to nuclear gene transfer.
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Affiliation(s)
- Alexandra-Sophie Roy
- Genomic Microbiology, Institute of General Microbiology, Kiel University, Kiel, Germany
| | - Christian Woehle
- Max Planck-Genome-Centre Cologne, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Julie LaRoche
- Department of Biology, Dalhousie University, Halifax, NS, Canada
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6
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Research on climate-change impact on Southern Ocean and Antarctic ecosystems after the UN Paris climate conference—“now more than ever” or “set sail to new shores”? Polar Biol 2016. [DOI: 10.1007/s00300-016-2059-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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Boyd PW, Bressac M. Developing a test-bed for robust research governance of geoengineering: the contribution of ocean iron biogeochemistry. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:20150299. [PMID: 29035263 PMCID: PMC5069533 DOI: 10.1098/rsta.2015.0299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/30/2016] [Indexed: 05/13/2023]
Abstract
Geoengineering to mitigate climate change has long been proposed, but remains nebulous. Exploration of the feasibility of geoengineering first requires the development of research governance to move beyond the conceptual towards scientifically designed pilot studies. Fortuitously, 12 mesoscale (approx. 1000 km2) iron enrichments, funded to investigate how ocean iron biogeochemistry altered Earth's carbon cycle in the geological past, provide proxies to better understand the benefits and drawbacks of geoengineering. The utility of these iron enrichments in the geoengineering debate is enhanced by the GEOTRACES global survey. Here, we outline how GEOTRACES surveys and process studies can provide invaluable insights into geoengineering. Surveys inform key unknowns including the regional influence and magnitude of modes of iron supply, and stimulate iron biogeochemical modelling. These advances will enable quantification of interannual variability of iron supply to assess whether any future purposeful multi-year iron-fertilization meets the principle of 'additionality' (sensu Kyoto protocol). Process studies address issues including upscaling of geoengineering, and how differing iron-enrichment strategies could stimulate wide-ranging biogeochemical outcomes. In summary, the availability of databases on both mesoscale iron-enrichment studies and the GEOTRACES survey, along with modelling, policy initiatives and legislation have positioned the iron-enrichment approach as a robust multifaceted test-bed to assess proposed research into climate intervention.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.
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Affiliation(s)
- Philip W Boyd
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems Collaborative Research Centre, University of Tasmania, Hobart, Tasmania, Australia
| | - Matthieu Bressac
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
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Morrissey J, Bowler C. Iron utilization in marine cyanobacteria and eukaryotic algae. Front Microbiol 2012; 3:43. [PMID: 22408637 PMCID: PMC3296057 DOI: 10.3389/fmicb.2012.00043] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 01/27/2012] [Indexed: 12/21/2022] Open
Abstract
Iron is essential for aerobic organisms. Additionally, photosynthetic organisms must maintain the iron-rich photosynthetic electron transport chain, which likely evolved in the iron-replete Proterozoic ocean. The subsequent rise in oxygen since those times has drastically decreased the levels of bioavailable iron, indicating that adaptations have been made to maintain sufficient cellular iron levels in the midst of scarcity. In combination with physiological studies, the recent sequencing of marine microorganism genomes and transcriptomes has begun to reveal the mechanisms of iron acquisition and utilization that allow marine microalgae to persist in iron limited environments.
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Affiliation(s)
- Joe Morrissey
- Ecole Normale Supérieur, Institut de Biologie de l'ENS Paris, France Inserm U1024, Paris, France CNRS UMR 8197, Paris, France
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9
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Hales B, Takahashi T. Mesoscale biogeochemical responses to iron fertilization in the upper layers of the Southern Ocean Iron Experiment areas. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc006956] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Ramirez-Llodra E, Tyler PA, Baker MC, Bergstad OA, Clark MR, Escobar E, Levin LA, Menot L, Rowden AA, Smith CR, Van Dover CL. Man and the last great wilderness: human impact on the deep sea. PLoS One 2011; 6:e22588. [PMID: 21829635 PMCID: PMC3148232 DOI: 10.1371/journal.pone.0022588] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 06/30/2011] [Indexed: 11/19/2022] Open
Abstract
The deep sea, the largest ecosystem on Earth and one of the least studied, harbours high biodiversity and provides a wealth of resources. Although humans have used the oceans for millennia, technological developments now allow exploitation of fisheries resources, hydrocarbons and minerals below 2000 m depth. The remoteness of the deep seafloor has promoted the disposal of residues and litter. Ocean acidification and climate change now bring a new dimension of global effects. Thus the challenges facing the deep sea are large and accelerating, providing a new imperative for the science community, industry and national and international organizations to work together to develop successful exploitation management and conservation of the deep-sea ecosystem. This paper provides scientific expert judgement and a semi-quantitative analysis of past, present and future impacts of human-related activities on global deep-sea habitats within three categories: disposal, exploitation and climate change. The analysis is the result of a Census of Marine Life--SYNDEEP workshop (September 2008). A detailed review of known impacts and their effects is provided. The analysis shows how, in recent decades, the most significant anthropogenic activities that affect the deep sea have evolved from mainly disposal (past) to exploitation (present). We predict that from now and into the future, increases in atmospheric CO(2) and facets and consequences of climate change will have the most impact on deep-sea habitats and their fauna. Synergies between different anthropogenic pressures and associated effects are discussed, indicating that most synergies are related to increased atmospheric CO(2) and climate change effects. We identify deep-sea ecosystems we believe are at higher risk from human impacts in the near future: benthic communities on sedimentary upper slopes, cold-water corals, canyon benthic communities and seamount pelagic and benthic communities. We finalise this review with a short discussion on protection and management methods.
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Affiliation(s)
- Eva Ramirez-Llodra
- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
| | - Paul A. Tyler
- School of Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, United Kingdom
| | - Maria C. Baker
- School of Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, United Kingdom
| | | | - Malcolm R. Clark
- National Institute of Water and Atmospheric Research, Wellington, New Zealand
| | - Elva Escobar
- Universidad Nacional Autónoma de México, Instituto de Ciencias del Mar y Limnología, México, D.F., Mexico
| | - Lisa A. Levin
- Integrative Oceanography Division, Scripps Institution of Oceanography, La Jolla, California, United States of America
| | | | - Ashley A. Rowden
- National Institute of Water and Atmospheric Research, Wellington, New Zealand
| | - Craig R. Smith
- Department of Oceanography, University of Hawaii, Honolulu, Hawaii, United States of America
| | - Cindy L. Van Dover
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, North Carolina, United States of America
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11
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Toxic diatoms and domoic acid in natural and iron enriched waters of the oceanic Pacific. Proc Natl Acad Sci U S A 2010; 107:20762-7. [PMID: 21068374 DOI: 10.1073/pnas.1006968107] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Near-surface waters ranging from the Pacific subarctic (58°N) to the Southern Ocean (66°S) contain the neurotoxin domoic acid (DA), associated with the diatom Pseudo-nitzschia. Of the 35 stations sampled, including ones from historic iron fertilization experiments (SOFeX, IronEx II), we found Pseudo-nitzschia at 34 stations and DA measurable at 14 of the 26 stations analyzed for DA. Toxin ranged from 0.3 fg·cell(-1) to 2 pg·cell(-1), comparable with levels found in similar-sized cells from coastal waters. In the western subarctic, descent of intact Pseudo-nitzschia likely delivered significant amounts of toxin (up to 4 μg of DA·m(-2)·d(-1)) to underlying mesopelagic waters (150-500 m). By reexamining phytoplankton samples from SOFeX and IronEx II, we found substantial amounts of DA associated with Pseudo-nitzschia. Indeed, at SOFeX in the Antarctic Pacific, DA reached 220 ng·L(-1), levels at which animal mortalities have occurred on continental shelves. Iron ocean fertilization also occurs naturally and may have promoted blooms of these ubiquitous algae over previous glacial cycles during deposition of iron-rich aerosols. Thus, the neurotoxin DA occurs both in coastal and oceanic waters, and its concentration, associated with changes in Pseudo-nitzschia abundance, likely varies naturally with climate cycles, as well as with artificial iron fertilization. Given that iron fertilization in iron-depleted regions of the sea has been proposed to enhance phytoplankton growth and, thereby, both reduce atmospheric CO(2) and moderate ocean acidification in surface waters, consideration of the potentially serious ecosystem impacts associated with DA is prudent.
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Perspectives on empirical approaches for ocean color remote sensing of chlorophyll in a changing climate. Proc Natl Acad Sci U S A 2010; 107:17073-8. [PMID: 20861445 DOI: 10.1073/pnas.0913800107] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phytoplankton biomass and productivity have been continuously monitored from ocean color satellites for over a decade. Yet, the most widely used empirical approach for estimating chlorophyll a (Chl) from satellites can be in error by a factor of 5 or more. Such variability is due to differences in absorption and backscattering properties of phytoplankton and related concentrations of colored-dissolved organic matter (CDOM) and minerals. The empirical algorithms have built-in assumptions that follow the basic precept of biological oceanography--namely, oligotrophic regions with low phytoplankton biomass are populated with small phytoplankton, whereas more productive regions contain larger bloom-forming phytoplankton. With a changing world ocean, phytoplankton composition may shift in response to altered environmental forcing, and CDOM and mineral concentrations may become uncoupled from phytoplankton stocks, creating further uncertainty and error in the empirical approaches. Hence, caution is warranted when using empirically derived Chl to infer climate-related changes in ocean biology. The Southern Ocean is already experiencing climatic shifts and shows substantial errors in satellite-derived Chl for different phytoplankton assemblages. Accurate global assessments of phytoplankton will require improved technology and modeling, enhanced field observations, and ongoing validation of our "eyes in space."
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13
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The influence of viral infection on a plankton ecosystem undergoing nutrient enrichment. J Theor Biol 2010; 265:225-37. [DOI: 10.1016/j.jtbi.2010.04.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 04/19/2010] [Accepted: 04/21/2010] [Indexed: 11/21/2022]
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Iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas. Proc Natl Acad Sci U S A 2010; 107:5887-92. [PMID: 20231473 DOI: 10.1073/pnas.0910579107] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Oceanic high-nitrate, low-chlorophyll environments have been highlighted for potential large-scale iron fertilizations to help mitigate global climate change. Controversy surrounds these initiatives, both in the degree of carbon removal and magnitude of ecosystem impacts. Previous open ocean enrichment experiments have shown that iron additions stimulate growth of the toxigenic diatom genus Pseudonitzschia. Most Pseudonitzschia species in coastal waters produce the neurotoxin domoic acid (DA), with their blooms causing detrimental marine ecosystem impacts, but oceanic Pseudonitzschia species are considered nontoxic. Here we demonstrate that the sparse oceanic Pseudonitzschia community at the high-nitrate, low-chlorophyll Ocean Station PAPA (50 degrees N, 145 degrees W) produces approximately 200 pg DA L(-1) in response to iron addition, that DA alters phytoplankton community structure to benefit Pseudonitzschia, and that oceanic cell isolates are toxic. Given the negative effects of DA in coastal food webs, these findings raise serious concern over the net benefit and sustainability of large-scale iron fertilizations.
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Robison BH. Conservation of deep pelagic biodiversity. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2009; 23:847-858. [PMID: 19627317 DOI: 10.1111/j.1523-1739.2009.01219.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The deep ocean is home to the largest ecosystems on our planet. This vast realm contains what may be the greatest number of animal species, the greatest biomass, and the greatest number of individual organisms in the living world. Humans have explored the deep ocean for about 150 years, and most of what is known is based on studies of the deep seafloor. In contrast, the water column above the deep seabed comprises more than 90% of the living space, yet less than 1% of this biome has been explored. The deep pelagic biota is the largest and least-known major faunal group on Earth despite its obvious importance at the global scale. Pelagic species represent an incomparable reservoir of biodiversity. Although we have yet to discover and describe the majority of these species, the threats to their continued existence are numerous and growing. Conserving deep pelagic biodiversity is a problem of global proportions that has never been addressed comprehensively. The potential effects of these threats include the extensive restructuring of entire ecosystems, changes in the geographical ranges of many species, large-scale elimination of taxa, and a decline in biodiversity at all scales. This review provides an initial framework of threat assessment for confronting the challenge of conserving deep pelagic biodiversity; and it outlines the need for baseline surveys and protected areas as preliminary policy goals.
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Affiliation(s)
- Bruce H Robison
- Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039-9644, USA.
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Smetacek V, Naqvi SWA. The next generation of iron fertilization experiments in the Southern Ocean. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2008; 366:3947-3967. [PMID: 18757280 DOI: 10.1098/rsta.2008.0144] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Of the various macro-engineering schemes proposed to mitigate global warming, ocean iron fertilization (OIF) is one that could be started at short notice on relevant scales. It is based on the reasoning that adding trace amounts of iron to iron-limited phytoplankton of the Southern Ocean will lead to blooms, mass sinking of organic matter and ultimately sequestration of significant amounts of atmospheric carbon dioxide (CO2) in the deep sea and sediments. This iron hypothesis, proposed by John Martin in 1990 (Martin 1990 Paleoceanography 5, 1-13), has been tested by five mesoscale experiments that provided strong support for its first condition: stimulation of a diatom bloom accompanied by significant CO2 drawdown. Nevertheless, a number of arguments pertaining to the fate of bloom biomass, the ratio of iron added to carbon sequestered and various side effects of fertilization, continue to cast doubt on its efficacy. The idea is also unpopular with the public because it is perceived as meddling with nature. However, this apparent consensus against OIF is premature because none of the published experiments were specifically designed to test its second condition pertaining to the fate of iron-induced organic carbon. Furthermore, the arguments on side effects are based on worst-case scenarios. These doubts, formulated as hypotheses, need to be tested in the next generation of OIF experiments. We argue that such experiments, if carried out at appropriate scales and localities, will not only show whether the technique will work, but will also reveal a wealth of insights on the structure and functioning of pelagic ecosystems in general and the krill-based Southern Ocean ecosystem, in particular. The outcomes of current models on the efficacy and side effects of OIF differ widely, so data from adequately designed experiments are urgently needed for realistic parametrization. OIF is likely to boost zooplankton stocks, including krill, which could have a positive effect on recovery of the great whale populations. Negative effects of possible commercialization of OIF can be controlled by the establishment of an international body headed by scientists to supervise and monitor its implementation.
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Affiliation(s)
- V Smetacek
- Alfred Wegener Institute for Polar and Marine Research, 27570 Bremerhaven, Germany.
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17
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Abstract
Developing technologies to reduce the rate of increase of atmospheric concentration of carbon dioxide (CO2) from annual emissions of 8.6PgCyr-1 from energy, process industry, land-use conversion and soil cultivation is an important issue of the twenty-first century. Of the three options of reducing the global energy use, developing low or no-carbon fuel and sequestering emissions, this manuscript describes processes for carbon (CO2) sequestration and discusses abiotic and biotic technologies. Carbon sequestration implies transfer of atmospheric CO2 into other long-lived global pools including oceanic, pedologic, biotic and geological strata to reduce the net rate of increase in atmospheric CO2. Engineering techniques of CO2 injection in deep ocean, geological strata, old coal mines and oil wells, and saline aquifers along with mineral carbonation of CO2 constitute abiotic techniques. These techniques have a large potential of thousands of Pg, are expensive, have leakage risks and may be available for routine use by 2025 and beyond. In comparison, biotic techniques are natural and cost-effective processes, have numerous ancillary benefits, are immediately applicable but have finite sink capacity. Biotic and abiotic C sequestration options have specific nitches, are complementary, and have potential to mitigate the climate change risks.
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Affiliation(s)
- Rattan Lal
- Carbon Management and Sequestration Center, The Ohio State University, Columbus, OH 43210, USA.
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18
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Sources of edaphic cyanobacterial diversity in the Dry Valleys of Eastern Antarctica. ISME JOURNAL 2008; 2:308-20. [PMID: 18239611 DOI: 10.1038/ismej.2007.104] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cyanobacteria are major components of Antarctic Dry Valley ecosystems. Their occurrence in lakes and ponds is well documented, however, less is known about their distribution in edaphic environments. There has been considerable debate about the contribution of aquatic organic matter derived largely from cyanobacteria to terrestrial ecosystems. In this study, automated rRNA intergenic spacer analysis (ARISA) and 16S rRNA gene clone libraries were used to investigate cyanobacterial diversity in a range of soil environments within the Miers and Beacon Valleys. These data were used to elucidate the input of aquatic cyanobacteria to soil communities. Thirty-eight samples were collected from a variety of soil environments including dry and moist soils, hypoliths and lake and hydroterrestrial microbial mats. The results from the ARISA and 16S rRNA clone library analysis demonstrated that diverse cyanobacterial communities exist within the mineral soils of the Miers Valley. The soil samples from Beacon Valley were depauparate in cyanobacterial signals. Within Miers Valley, significant portions (29%-58%) of ARISA fragment lengths found in aquatic cyanobacterial mats were also present in soil and hypolith samples, indicating that lacustrine and hydroterrestrial cyanobacteria play a significant role in structuring soil communities. The influence of abiotic variables on the community structure of soil samples was assessed using BEST analysis. The results of BEST analysis of samples from within Miers Valley showed that total percentage of carbon content was the most important variable in explaining differences in cyanobacterial community structure. The BEST analyses indicated that four elements contributed significantly to species compositional differences between valleys. We suggest that the complete absence of lakes or ponds from Beacon Valley is a contributing factor to the low cyanobacterial component of these soils.
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Abstract
Life on Earth most likely originated as microorganisms in the sea. Over the past approximately 3.5 billion years, microorganisms have shaped and defined Earth's biosphere and have created conditions that have allowed the evolution of macroorganisms and complex biological communities, including human societies. Recent advances in technology have highlighted the vast and previously unknown genetic information that is contained in extant marine microorganisms, from new protein families to novel metabolic processes. Now there is a unique opportunity, using recent advances in molecular ecology, metagenomics, remote sensing of microorganisms and ecological modelling, to achieve a comprehensive understanding of marine microorganisms and their susceptibility to environmental variability and climate change. Contemporary microbial oceanography is truly a sea of opportunity and excitement.
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Affiliation(s)
- David M Karl
- University of Hawaii, Honolulu, Hawaii 96822, USA.
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20
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Tang KW, Grossart HP. Iron effects on colonization behavior, motility, and enzymatic activity of marine bacteria. Can J Microbiol 2007; 53:968-74. [PMID: 17898853 DOI: 10.1139/w07-059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Iron availability in the ocean has been shown to affect the growth and production of phytoplankton and free-living bacteria. A large fraction of marine bacteria are specialized in colonizing and living on particles and aggregates, but the effects of iron limitation on these bacteria are not fully known. We conducted laboratory experiments to study the effects of iron availability on particle colonization behavior, motility, and enzymatic activities of 4 strains of marine bacteria. Iron depletion reduced the bacterial particle colonization rate by 1.7%–43.1%, which could be attributed to reduced swimming speeds in 2 of the 4 strains. Protease activity was not affected by iron availability. However, attached bacteria did show higher protease activities than their free counterparts. Our results suggest that iron limitation in the ocean could in some cases reduce bacteria–particle interactions by reducing bacterial motility and colonization rate.
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Affiliation(s)
- Kam W Tang
- Virginia Institute of Marine Science, 1208 Greate Road, Gloucester Point, Virginia 23062, USA.
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Abstract
Removal by fishing of large sharks has reduced predation-pressure on shark prey and, via a trophic cascade, caused clam populations to crash. This indirect response illustrates why fisheries should be managed in a whole-ecosystem context.
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Affiliation(s)
- Andrew S Brierley
- Pelagic Ecology Research Group, Gatty Marine Laboratory, University of St. Andrews, Fife, Scotland, UK.
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Blain S, Quéguiner B, Armand L, Belviso S, Bombled B, Bopp L, Bowie A, Brunet C, Brussaard C, Carlotti F, Christaki U, Corbière A, Durand I, Ebersbach F, Fuda JL, Garcia N, Gerringa L, Griffiths B, Guigue C, Guillerm C, Jacquet S, Jeandel C, Laan P, Lefèvre D, Lo Monaco C, Malits A, Mosseri J, Obernosterer I, Park YH, Picheral M, Pondaven P, Remenyi T, Sandroni V, Sarthou G, Savoye N, Scouarnec L, Souhaut M, Thuiller D, Timmermans K, Trull T, Uitz J, van Beek P, Veldhuis M, Vincent D, Viollier E, Vong L, Wagener T. Effect of natural iron fertilization on carbon sequestration in the Southern Ocean. Nature 2007; 446:1070-4. [PMID: 17460670 DOI: 10.1038/nature05700] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Accepted: 02/26/2007] [Indexed: 11/09/2022]
Abstract
The availability of iron limits primary productivity and the associated uptake of carbon over large areas of the ocean. Iron thus plays an important role in the carbon cycle, and changes in its supply to the surface ocean may have had a significant effect on atmospheric carbon dioxide concentrations over glacial-interglacial cycles. To date, the role of iron in carbon cycling has largely been assessed using short-term iron-addition experiments. It is difficult, however, to reliably assess the magnitude of carbon export to the ocean interior using such methods, and the short observational periods preclude extrapolation of the results to longer timescales. Here we report observations of a phytoplankton bloom induced by natural iron fertilization--an approach that offers the opportunity to overcome some of the limitations of short-term experiments. We found that a large phytoplankton bloom over the Kerguelen plateau in the Southern Ocean was sustained by the supply of iron and major nutrients to surface waters from iron-rich deep water below. The efficiency of fertilization, defined as the ratio of the carbon export to the amount of iron supplied, was at least ten times higher than previous estimates from short-term blooms induced by iron-addition experiments. This result sheds new light on the effect of long-term fertilization by iron and macronutrients on carbon sequestration, suggesting that changes in iron supply from below--as invoked in some palaeoclimatic and future climate change scenarios--may have a more significant effect on atmospheric carbon dioxide concentrations than previously thought.
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Affiliation(s)
- Stéphane Blain
- Laboratoire d'Océanographie et de Biogéochimie, Centre Océanologique de Marseille, CNRS, Université de la Méditerranée, campus de Luminy, case 901, 13288 Marseille Cedex 09, France.
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Schlesinger WH. The Global Carbon Cycle and Climate Change. ADVANCES IN THE ECONOMICS OF ENVIRONMENTAL RESOURCES 2005. [DOI: 10.1016/s1569-3740(05)05002-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Tagliabue A, Arrigo KR. Iron in the Ross Sea: 1. Impact on CO2
fluxes via variation in phytoplankton functional group and non-Redfield stoichiometry. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jc002531] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Kevin R. Arrigo
- Department of Geophysics; Stanford University; Stanford California USA
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Vetter EW. Insights into the ecological effects of deep ocean CO2enrichment: The impacts of natural CO2venting at Loihi seamount on deep sea scavengers. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jc002617] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Pörtner HO. Synergistic effects of temperature extremes, hypoxia, and increases in CO2on marine animals: From Earth history to global change. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jc002561] [Citation(s) in RCA: 296] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Affiliation(s)
- Philip Boyd
- National Institute of Water and Atmosphere, Department of Chemistry, University of Otago, Dunedin, New Zealand.
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Boyd PW, Law CS, Wong CS, Nojiri Y, Tsuda A, Levasseur M, Takeda S, Rivkin R, Harrison PJ, Strzepek R, Gower J, McKay M, Abraham E, Arychuk M, Barwell-Clarke J, Crawford W, Crawford D, Hale M, Harada K, Johnson K, Kiyosawa H, Kudo I, Marchetti A, Miller W, Needoba J, Nishioka J, Ogawa H, Page J, Robert M, Saito H, Sastri A, Sherry N, Soutar T, Sutherland N, Taira Y, Whitney F, Wong SKE, Yoshimura T. The decline and fate of an iron-induced subarctic phytoplankton bloom. Nature 2004; 428:549-53. [PMID: 15058302 DOI: 10.1038/nature02437] [Citation(s) in RCA: 393] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters. However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown. Here we report on the decline and fate of an iron-stimulated diatom bloom in the Gulf of Alaska. The bloom terminated on day 18, following the depletion of iron and then silicic acid, after which mixed-layer particulate organic carbon (POC) concentrations declined over six days. Increased particulate silica export via sinking diatoms was recorded in sediment traps at depths between 50 and 125 m from day 21, yet increased POC export was not evident until day 24. Only a small proportion of the mixed-layer POC was intercepted by the traps, with more than half of the mixed-layer POC deficit attributable to bacterial remineralization and mesozooplankton grazing. The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.
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Affiliation(s)
- Philip W Boyd
- NIWA Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, PO Box 56, Dunedin, 9003, New Zealand.
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Cavet JS, Borrelly GPM, Robinson NJ. Zn, Cu and Co in cyanobacteria: selective control of metal availability. FEMS Microbiol Rev 2003; 27:165-81. [PMID: 12829266 DOI: 10.1016/s0168-6445(03)00050-0] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Homeostatic systems for essential and non-essential metals create the cellular environments in which the correct metals are acquired by metalloproteins while the incorrect ones are somehow avoided. Cyanobacteria have metal requirements often absent from other bacteria; copper in thylakoidal plastocyanin, zinc in carboxysomal carbonic anhydrase, cobalt in cobalamin but magnesium in chlorophyll, molybdenum in heterocystous nitrogenase, manganese in thylakoidal water-splitting oxygen-evolving complex. This article reviews: an intracellular trafficking pathway for inward copper supply, the sequestration of surplus zinc by metallothionein (also present in other bacteria) and the detection and export of excess cobalt. We consider the influence of homeostatic proteins on selective metal availability.
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Affiliation(s)
- Jennifer S Cavet
- Biosciences, Medical School, University of Newcastle, Newcastle NE2 4HH, UK
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Affiliation(s)
- Ken O Buesseler
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
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Yamasaki A. An Overview of CO2 Mitigation Options for Global Warming-Emphasizing CO2 Sequestration Options. JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 2003. [DOI: 10.1252/jcej.36.361] [Citation(s) in RCA: 257] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Akihiro Yamasaki
- Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology
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Chu S, Elliott S, Maltrud ME. Global eddy permitting simulations of surface ocean nitrogen, iron, sulfur cycling. CHEMOSPHERE 2003; 50:223-235. [PMID: 12653294 DOI: 10.1016/s0045-6535(02)00162-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The geocycles of N, Fe and S in the ocean are tightly coupled and together exert strong influence on biogeochemistry of the earth system. We investigate this interaction by inserting macro-micronutrient cycling into a high resolution ocean model that realistically represents the general circulation. Simulated chlorophyll distributions reproduce many features of satellite-based measurements of ocean color. Meridional sections through model results and seasonally averaged SeaWiFS data agree reasonably well, both in the oligotrophic gyres and along fronts. Discrepancies are associated in many cases with shelf, ridge or island effects. Dimethyl sulfide peaks and their chlorophyll correlations are similar to those obtained on major oceanographic expeditions. Lack of strong regional relationships between the sulfide and phytoplankton may be partly explained by correspondence between time constants for production and for the traversal of mesoscale transport features. In general the eddies and filaments of tropical instability waves are well represented, including the onset of the 1997-1998 El Niño. North-south shifts of the transition zone chlorophyll front appear prominently in the results.
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Affiliation(s)
- Shaoping Chu
- Earth and Environmental Sciences Division, Atmospheric and Climate Sciences Group, MS D401, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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