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Jiang HB, Hutchins DA, Ma W, Zhang RF, Wells M, Jiao N, Wang Y, Chai F. Natural ocean iron fertilization and climate variability over geological periods. GLOBAL CHANGE BIOLOGY 2023; 29:6856-6866. [PMID: 37855153 DOI: 10.1111/gcb.16990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 09/20/2023] [Accepted: 09/27/2023] [Indexed: 10/20/2023]
Abstract
Marine primary producers are largely dependent on and shape the Earth's climate, although their relationship with climate varies over space and time. The growth of phytoplankton and associated marine primary productivity in most of the modern global ocean is limited by the supply of nutrients, including the micronutrient iron. The addition of iron via episodic and frequent events drives the biological carbon pump and promotes the sequestration of atmospheric carbon dioxide (CO2 ) into the ocean. However, the dependence between iron and marine primary producers adaptively changes over different geological periods due to the variation in global climate and environment. In this review, we examined the role and importance of iron in modulating marine primary production during some specific geological periods, that is, the Great Oxidation Event (GOE) during the Huronian glaciation, the Snowball Earth Event during the Cryogenian, the glacial-interglacial cycles during the Pleistocene, and the period from the last glacial maximum to the late Holocene. Only the change trend of iron bioavailability and climate in the glacial-interglacial cycles is consistent with the Iron Hypothesis. During the GOE and the Snowball Earth periods, although the bioavailability of iron in the ocean and the climate changed dramatically, the changing trend of many factors contradicted the Iron Hypothesis. By detangling the relationship among marine primary productivity, iron availability and oceanic environments in different geological periods, this review can offer some new insights for evaluating the impact of ocean iron fertilization on removing CO2 from the atmosphere and regulating the climate.
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Affiliation(s)
- Hai-Bo Jiang
- Key Laboratory of Marine Biotechnology of Zhejiang Province, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, China
| | - David A Hutchins
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Wentao Ma
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
| | - Rui-Feng Zhang
- School of Oceanography, Shanghai Jiaotong University, Shanghai, Shanghai, China
| | - Mark Wells
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- School of Marine Sciences, University of Maine, Orono, Maine, USA
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Sciences, Xiamen University, Xiamen, Fujian, China
| | - Yuntao Wang
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
| | - Fei Chai
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- State Key Laboratory of Marine Environmental Sciences, Xiamen University, Xiamen, Fujian, China
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2
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Zan J, Maher B, Yamazaki T, Fang X, Han W, Kang J, Hu Z. Mid-Pleistocene links between Asian dust, Tibetan glaciers, and Pacific iron fertilization. Proc Natl Acad Sci U S A 2023; 120:e2304773120. [PMID: 37279267 PMCID: PMC10268273 DOI: 10.1073/pnas.2304773120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 05/08/2023] [Indexed: 06/08/2023] Open
Abstract
Increasing Asian dust fluxes, associated with late Cenozoic cooling and intensified glaciations, are conventionally thought to drive iron fertilization of phytoplankton productivity in the North Pacific, contributing to ocean carbon storage and drawdown of atmospheric CO2. During the early Pleistocene glaciations, however, productivity remained low despite higher Asian dust fluxes, only displaying glacial stage increases after the mid-Pleistocene climate transition (~800 ka B.P.). We solve this paradox by analyzing an Asian dust sequence, spanning the last 3.6 My, from the Tarim Basin, identifying a major switch in the iron composition of the dust at ~800 ka, associated with expansion of Tibetan glaciers and enhanced production of freshly ground rock minerals. This compositional shift in the Asian dust was recorded synchronously in the downwind, deep sea sediments of the central North Pacific. The switch from desert dust, containing stable, highly oxidized iron, to glacial dust, richer in reactive reduced iron, coincided with increased populations of silica-producing phytoplankton in the equatorial North Pacific and increased primary productivity in more northerly locations, such as the South China Sea. We calculate that potentially bioavailable Fe2+ flux to the North Pacific was more than doubled after the switch to glacially- sourced dust. These findings indicate a positive feedback between Tibetan glaciations, glaciogenic production of dust with enhanced iron bioavailability, and changes in North Pacific iron fertilization. Notably, this strengthened link between climate and eolian dust coincided with the mid-Pleistocene transition to increased storage of C in the glacial North Pacific and more intense northern hemisphere glaciations.
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Affiliation(s)
- Jinbo Zan
- State Key Laboratory of Tibetan Plateau Earth System and Resources Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing100101China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing1000449China
| | - Barbara A. Maher
- Centre for Environmental Magnetism & Palaeomagnetism, Lancaster Environment Centre, University of Lancaster,LancasterLA1 4YQ, UK
| | - Toshitsugu Yamazaki
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa277-8564, Japan
| | - Xiaomin Fang
- State Key Laboratory of Tibetan Plateau Earth System and Resources Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing100101China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing1000449China
| | - Wenxia Han
- School of Resource and Environmental Sciences, Linyi University,276000Linyi, China
| | - Jian Kang
- State Key Laboratory of Tibetan Plateau Earth System and Resources Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing100101China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing1000449China
| | - Zhe Hu
- State Key Laboratory of Tibetan Plateau Earth System and Resources Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing100101China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing1000449China
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3
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Kholssi R, Lougraimzi H, Moreno-Garrido I. Effects of global environmental change on microalgal photosynthesis, growth and their distribution. MARINE ENVIRONMENTAL RESEARCH 2023; 184:105877. [PMID: 36640723 DOI: 10.1016/j.marenvres.2023.105877] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 06/17/2023]
Abstract
Global climate change (GCC) constitutes a complex challenge posing a serious threat to biodiversity and ecosystems in the next decades. There are several recent studies dealing with the potential effect of increased temperature, decrease of pH or shifts in salinity, as well as cascading events of GCC and their impact on human-environment systems. Microalgae as primary producers are a sensitive compartment of the marine ecosystems to all those changes. However, the potential consequences of these changes for marine microalgae have received relatively little attention and they are still not well understood. Thus, there is an urgent need to explore and understand the effects generated by multiple climatic changes on marine microalgae growth and biodiversity. Therefore, this review aimed to compare and contrast mechanisms that marine microalgae exhibit to directly respond to harsh conditions associated with GCC and the potential consequences of those changes in marine microalgal populations. Literature shows that microalgae responses to environmental stressors such as temperature were affected differently. A stress caused by salinity might slow down cell division, reduces size, ceases motility, and triggers palmelloid formation in microalgae community, but some of these changes are strongly species-specific. UV irradiance can potentially lead to an oxidative stress in microalgae, promoting the production of reactive oxygen species (ROS) or induce direct physical damage on microalgae, then inhibiting the growth of microalgae. Moreover, pH could impact many groups of microalgae being more tolerant of certain pH shifts, while others were sensitive to changes of just small units (such as coccolithophorids) and subsequently affect the species at a higher trophic level, but also total vertical carbon transport in oceans. Overall, this review highlights the importance of examining effects of multiple stressors, considering multiple responses to understand the complexity behind stressor interactions.
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Affiliation(s)
- Rajaa Kholssi
- Composting Research Group, Faculty of Sciences, University of Burgos, Burgos, Spain; Ecology and Coastal Management, Institute of Marine Sciences of Andalusia (ICMAN-CSIC), Campus Río San Pedro, 11510, Puerto Real, Cádiz, Spain.
| | - Hanane Lougraimzi
- Laboratory of Plant, Animal and Agro-Industry Productions, Faculty of Sciences, Ibn Tofail University, BP: 242, 14000, Kenitra, Morocco
| | - Ignacio Moreno-Garrido
- Ecology and Coastal Management, Institute of Marine Sciences of Andalusia (ICMAN-CSIC), Campus Río San Pedro, 11510, Puerto Real, Cádiz, Spain
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4
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Evidence for late-glacial oceanic carbon redistribution and discharge from the Pacific Southern Ocean. Nat Commun 2022; 13:6250. [PMID: 36369161 PMCID: PMC9652385 DOI: 10.1038/s41467-022-33753-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 09/30/2022] [Indexed: 11/13/2022] Open
Abstract
Southern Ocean deep-water circulation plays a vital role in the global carbon cycle. On geological time scales, upwelling along the Chilean margin likely contributed to the deglacial atmospheric carbon dioxide rise, but little quantitative evidence exists of carbon storage. Here, we develop an X-ray Micro-Computer-Tomography method to assess foraminiferal test dissolution as proxy for paleo-carbonate ion concentrations ([CO32-]). Our subantarctic Southeast Pacific sediment core depth transect shows significant deep-water [CO32-] variations during the Last Glacial Maximum and Deglaciation (10-22 ka BP). We provide evidence for an increase in [CO32-] during the early-deglacial period (15-19 ka BP) in Lower Circumpolar Deepwater. The export of such low-carbon deep-water from the Pacific to the Atlantic contributed to significantly lowered carbon storage within the Southern Ocean, highlighting the importance of a dynamic Pacific-Southern Ocean deep-water reconfiguration for shaping late-glacial oceanic carbon storage, and subsequent deglacial oceanic-atmospheric CO2 transfer.
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Chen Y, Chen M, Chen J, Fan L, Zheng M, Qiu Y. Dual isotopes of nitrite in the Amundsen Sea in summer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 843:157055. [PMID: 35780884 DOI: 10.1016/j.scitotenv.2022.157055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/25/2022] [Accepted: 06/25/2022] [Indexed: 06/15/2023]
Abstract
Nitrite (NO2-) is a key intermediate in the nitrogen (N) cycle, and its transformation is accomplished by microbial communities. However, due to few studies on the nitrite cycle, a clear assessment of the contribution to the marine biogeochemical cycle is missing. Here, we present data on nitrogen and oxygen isotopic composition of NO2- in the Amundsen Sea in summer, and explore the biogeochemical processes that influence the NO2- cycle. Extremely low δ15NNO2 and abnormally high δ18ONO2 were found in the upper waters of the Amundsen Sea, with δ15NNO2 as low as -58.4 ‰ and δ18ONO2 as high as 44.4 ‰. Enzymatic isotopic exchange reactions between nitrate and nitrite have been proposed to be responsible for these isotopic anomalies. The mirror-symmetrical variation between δ15NNO2 and δ18ONO2 suggests that the isotopic fractionation effects of nitrogen and oxygen are opposite in isotope exchange reactions. Dual isotopes of nitrite indicate that ammonia oxidation is the main source of nitrite, thus nitrification plays an important role in the formation of primary nitrite maximum in the upper Amundsen Sea. The nitrogen and oxygen isotopic compositions of nitrite provide support for clarifying multiple processes of marine nitrogen cycle.
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Affiliation(s)
- Yangjun Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Min Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China.
| | - Jinxu Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Lingfang Fan
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Mingfang Zheng
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Yusheng Qiu
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
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6
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Abbass K, Qasim MZ, Song H, Murshed M, Mahmood H, Younis I. A review of the global climate change impacts, adaptation, and sustainable mitigation measures. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:42539-42559. [PMID: 35378646 PMCID: PMC8978769 DOI: 10.1007/s11356-022-19718-6] [Citation(s) in RCA: 98] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 03/10/2022] [Indexed: 05/19/2023]
Abstract
Climate change is a long-lasting change in the weather arrays across tropics to polls. It is a global threat that has embarked on to put stress on various sectors. This study is aimed to conceptually engineer how climate variability is deteriorating the sustainability of diverse sectors worldwide. Specifically, the agricultural sector's vulnerability is a globally concerning scenario, as sufficient production and food supplies are threatened due to irreversible weather fluctuations. In turn, it is challenging the global feeding patterns, particularly in countries with agriculture as an integral part of their economy and total productivity. Climate change has also put the integrity and survival of many species at stake due to shifts in optimum temperature ranges, thereby accelerating biodiversity loss by progressively changing the ecosystem structures. Climate variations increase the likelihood of particular food and waterborne and vector-borne diseases, and a recent example is a coronavirus pandemic. Climate change also accelerates the enigma of antimicrobial resistance, another threat to human health due to the increasing incidence of resistant pathogenic infections. Besides, the global tourism industry is devastated as climate change impacts unfavorable tourism spots. The methodology investigates hypothetical scenarios of climate variability and attempts to describe the quality of evidence to facilitate readers' careful, critical engagement. Secondary data is used to identify sustainability issues such as environmental, social, and economic viability. To better understand the problem, gathered the information in this report from various media outlets, research agencies, policy papers, newspapers, and other sources. This review is a sectorial assessment of climate change mitigation and adaptation approaches worldwide in the aforementioned sectors and the associated economic costs. According to the findings, government involvement is necessary for the country's long-term development through strict accountability of resources and regulations implemented in the past to generate cutting-edge climate policy. Therefore, mitigating the impacts of climate change must be of the utmost importance, and hence, this global threat requires global commitment to address its dreadful implications to ensure global sustenance.
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Affiliation(s)
- Kashif Abbass
- School of Economics and Management, Nanjing University of Science and Technology, Nanjing, 210094 People’s Republic of China
| | - Muhammad Zeeshan Qasim
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, 210094 People’s Republic of China
| | - Huaming Song
- School of Economics and Management, Nanjing University of Science and Technology, Nanjing, 210094 People’s Republic of China
| | - Muntasir Murshed
- School of Business and Economics, North South University, Dhaka, 1229 Bangladesh
- Department of Journalism, Media and Communications, Daffodil International University, Dhaka, Bangladesh
| | - Haider Mahmood
- Department of Finance, College of Business Administration, Prince Sattam Bin Abdulaziz University, 173, Alkharj, 11942 Saudi Arabia
| | - Ijaz Younis
- School of Economics and Management, Nanjing University of Science and Technology, Nanjing, 210094 People’s Republic of China
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7
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Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years. Nat Commun 2022; 13:2044. [PMID: 35440628 PMCID: PMC9018689 DOI: 10.1038/s41467-022-29642-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 03/25/2022] [Indexed: 11/08/2022] Open
Abstract
The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO2 levels.
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8
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Yang JW, Brandon M, Landais A, Duchamp-Alphonse S, Blunier T, Prié F, Extier T. Global biosphere primary productivity changes during the past eight glacial cycles. Science 2022; 375:1145-1151. [PMID: 35271325 DOI: 10.1126/science.abj8826] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Global biosphere productivity is the largest uptake flux of atmospheric carbon dioxide (CO2), and it plays an important role in past and future carbon cycles. However, global estimation of biosphere productivity remains a challenge. Using the ancient air enclosed in polar ice cores, we present the first 800,000-year record of triple isotopic ratios of atmospheric oxygen, which reflects past global biosphere productivity. We observe that global biosphere productivity in the past eight glacial intervals was lower than that in the preindustrial era and that, in most cases, it starts to increase millennia before deglaciations. Both variations occur concomitantly with CO2 changes, implying a dominant control of CO2 on global biosphere productivity that supports a pervasive negative feedback under the glacial climate.
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Affiliation(s)
- Ji-Woong Yang
- Laboratoire des Sciences du Climat et de l'Environnement/Institut Pierre-Simon Laplace, Université Paris Saclay/CEA/CNRS/UVSQ, Gif-sur-Yvette, France
| | - Margaux Brandon
- Laboratoire des Sciences du Climat et de l'Environnement/Institut Pierre-Simon Laplace, Université Paris Saclay/CEA/CNRS/UVSQ, Gif-sur-Yvette, France.,Géosciences Paris-Saclay, Université Paris Saclay, Orsay, France
| | - Amaëlle Landais
- Laboratoire des Sciences du Climat et de l'Environnement/Institut Pierre-Simon Laplace, Université Paris Saclay/CEA/CNRS/UVSQ, Gif-sur-Yvette, France
| | | | - Thomas Blunier
- Niels Bohr Institute, University of Copenhagen, København N, Denmark
| | - Frédéric Prié
- Laboratoire des Sciences du Climat et de l'Environnement/Institut Pierre-Simon Laplace, Université Paris Saclay/CEA/CNRS/UVSQ, Gif-sur-Yvette, France
| | - Thomas Extier
- Laboratoire des Sciences du Climat et de l'Environnement/Institut Pierre-Simon Laplace, Université Paris Saclay/CEA/CNRS/UVSQ, Gif-sur-Yvette, France
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9
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Abstract
Large changes in global ecosystem productivity are set in motion by carbon dioxide rise.
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Affiliation(s)
- Corinne Le Quéré
- School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Nicolas Mayot
- School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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10
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Pagnone A, Koch F, Pausch F, Trimborn S. The Southern Ocean diatom Pseudo-nitzschia subcurvata flourished better under simulated glacial than interglacial ocean conditions: Combined effects of CO2 and iron. PLoS One 2021; 16:e0260649. [PMID: 34890411 PMCID: PMC8664213 DOI: 10.1371/journal.pone.0260649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 11/12/2021] [Indexed: 11/19/2022] Open
Abstract
The 'Iron Hypothesis' suggests a fertilization of the Southern Ocean by increased dust deposition in glacial times. This promoted high primary productivity and contributed to lower atmospheric pCO2. In this study, the diatom Pseudo-nitzschia subcurvata, known to form prominent blooms in the Southern Ocean, was grown under simulated glacial and interglacial climatic conditions to understand how iron (Fe) availability (no Fe or Fe addition) in conjunction with different pCO2 levels (190 and 290 μatm) influences growth, particulate organic carbon (POC) production and photophysiology. Under both glacial and interglacial conditions, the diatom grew with similar rates. In comparison, glacial conditions (190 μatm pCO2 and Fe input) favored POC production by P. subcurvata while under interglacial conditions (290 μatm pCO2 and Fe deficiency) POC production was reduced, indicating a negative effect caused by higher pCO2 and low Fe availability. Under interglacial conditions, the diatom had, however, thicker silica shells. Overall, our results show that the combination of higher Fe availability with low pCO2, present during the glacial ocean, was beneficial for the diatom P. subcurvata, thus contributing more to primary production during glacial compared to interglacial times. Under the interglacial ocean conditions, on the other hand, the diatom could have contributed to higher carbon export due to its higher degree of silicification.
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Affiliation(s)
- Anna Pagnone
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Florian Koch
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Franziska Pausch
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Scarlett Trimborn
- EcoTrace, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
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11
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Kobayashi H, Oka A, Yamamoto A, Abe-Ouchi A. Glacial carbon cycle changes by Southern Ocean processes with sedimentary amplification. SCIENCE ADVANCES 2021; 7:7/35/eabg7723. [PMID: 34433564 PMCID: PMC8386940 DOI: 10.1126/sciadv.abg7723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
Recent paleo reconstructions suggest that increased carbon storage in the Southern Ocean during glacial periods contributed to low glacial atmospheric carbon dioxide concentration (pCO2). However, quantifying its contribution in three-dimensional ocean general circulation models (OGCMs) has proven challenging. Here, we show that OGCM simulation with sedimentary process considering enhanced Southern Ocean salinity stratification and iron fertilization from glaciogenic dust during glacial periods improves model-data agreement of glacial deep water with isotopically light carbon, low oxygen, and old radiocarbon ages. The glacial simulation shows a 77-ppm reduction of atmospheric pCO2, which closely matches the paleo record. The Southern Ocean salinity stratification and the iron fertilization from glaciogenic dust amplified the carbonate sedimentary feedback, which caused most of the increased carbon storage in the deep ocean and played an important role in pCO2 reduction. The model-data agreement of Southern Ocean properties is crucial for simulating glacial changes in the ocean carbon cycle.
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Affiliation(s)
- Hidetaka Kobayashi
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan.
| | - Akira Oka
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
| | - Akitomo Yamamoto
- Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
| | - Ayako Abe-Ouchi
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
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12
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Raja M, Rosell-Melé A. Appraisal of sedimentary alkenones for the quantitative reconstruction of phytoplankton biomass. Proc Natl Acad Sci U S A 2021; 118:e2014787118. [PMID: 33380457 PMCID: PMC7812761 DOI: 10.1073/pnas.2014787118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Marine primary productivity (PP) is the driving factor in the global marine carbon cycle. Its reconstruction in past climates relies on biogeochemical proxies that are not considered to provide an unequivocal signal. These are often based on the water column flux of biogenic components to sediments (organic carbon, biogenic opal, biomarkers), although other factors than productivity are posited to control the sedimentary contents of the components, and their flux is related to the fraction of export production buried in sediments. Moreover, most flux proxies have not been globally appraised. Here, we assess a proxy to quantify past phytoplankton biomass by correlating the concentration of C37 alkenones in a global suite of core-top sediments with sea surface chlorophyll-a (SSchla) estimates over the last 20 y. SSchla is the central metric to calculate phytoplankton biomass and is directly related to PP. We show that the global spatial distribution of sedimentary alkenones is primarily correlated to SSchla rather than diagenetic factors such as the oxygen concentration in bottom waters, which challenges previous assumptions on the role of preservation on driving concentrations of sedimentary organic compounds. Moreover, our results suggest that the rate of global carbon export to sediments is not regionally constrained, and that alkenones producers play a dominant role in the global export of carbon buried in the seafloor. This study shows the potential of using sedimentary alkenones to estimate past phytoplankton biomass, which in turn can be used to infer past PP in the global ocean.
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Affiliation(s)
- Maria Raja
- Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain;
| | - Antoni Rosell-Melé
- Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain
- Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Catalonia, Spain
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13
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Ai XE, Studer AS, Sigman DM, Martínez-García A, Fripiat F, Thöle LM, Michel E, Gottschalk J, Arnold L, Moretti S, Schmitt M, Oleynik S, Jaccard SL, Haug GH. Southern Ocean upwelling, Earth's obliquity, and glacial-interglacial atmospheric CO 2 change. Science 2020; 370:1348-1352. [PMID: 33303618 DOI: 10.1126/science.abd2115] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 10/30/2020] [Indexed: 11/02/2022]
Abstract
Previous studies have suggested that during the late Pleistocene ice ages, surface-deep exchange was somehow weakened in the Southern Ocean's Antarctic Zone, which reduced the leakage of deeply sequestered carbon dioxide and thus contributed to the lower atmospheric carbon dioxide levels of the ice ages. Here, high-resolution diatom-bound nitrogen isotope measurements from the Indian sector of the Antarctic Zone reveal three modes of change in Southern Westerly Wind-driven upwelling, each affecting atmospheric carbon dioxide. Two modes, related to global climate and the bipolar seesaw, have been proposed previously. The third mode-which arises from the meridional temperature gradient as affected by Earth's obliquity (axial tilt)-can explain the lag of atmospheric carbon dioxide behind climate during glacial inception and deglaciation. This obliquity-induced lag, in turn, makes carbon dioxide a delayed climate amplifier in the late Pleistocene glacial cycles.
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Affiliation(s)
- Xuyuan E Ai
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA. .,Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Anja S Studer
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Daniel M Sigman
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | | | - François Fripiat
- Department of Geosciences, Environment and Society, Université Libre de Bruxelles, Brussels, Belgium
| | - Lena M Thöle
- Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland.,Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Elisabeth Michel
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Laboratoire CNRS-CEA-UVSQ, Gif-sur-Yvette, France
| | | | - Laura Arnold
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | - Simone Moretti
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.,Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
| | - Mareike Schmitt
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Sergey Oleynik
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Samuel L Jaccard
- Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland
| | - Gerald H Haug
- Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.,Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
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14
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Abstract
Wildfire can influence climate directly and indirectly, but little is known about the relationships between wildfire and climate during the Quaternary, especially how wildfire patterns varied over glacial-interglacial cycles. Here, we present a high-resolution soot record from the Chinese Loess Plateau; this is a record of large-scale, high-intensity fires over the past 2.6 My. We observed a unique and distinct glacial-interglacial cyclicity of soot over the entire Quaternary Period synchronous with marine δ18O and dust records, which suggests that ice-volume-modulated aridity controlled wildfire occurrences, soot production, and dust fluxes in central Asia. The high-intensity fires were also found to be anticorrelated with global atmospheric CO2 records over the past eight glacial-interglacial cycles, implying a possible connection between the fires, dust, and climate mediated through the iron cycle. The significance of this hypothetical connection remains to be determined, but the relationships revealed in this study hint at the potential importance of wildfire for the global climate system.
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15
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16
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Galbraith ED, Skinner LC. The Biological Pump During the Last Glacial Maximum. ANNUAL REVIEW OF MARINE SCIENCE 2020; 12:559-586. [PMID: 31899673 DOI: 10.1146/annurev-marine-010419-010906] [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] [Indexed: 06/10/2023]
Abstract
Much of the global cooling during ice ages arose from changes in ocean carbon storage that lowered atmospheric CO2. A slew of mechanisms, both physical and biological, have been proposed as key drivers of these changes. Here we discuss the current understanding of these mechanisms with a focus on how they altered the theoretically defined soft-tissue and biological disequilibrium carbon storage at the peak of the last ice age. Observations and models indicate a role for Antarctic sea ice through its influence on ocean circulation patterns, but other mechanisms, including changes in biological processes, must have been important as well, and may have been coordinated through links with global air temperature. Further research is required to better quantify the contributions of the various mechanisms, and there remains great potential to use the Last Glacial Maximum and the ensuing global warming as natural experiments from which to learn about climate-driven changes in the marine ecosystem.
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Affiliation(s)
- Eric D Galbraith
- Department of Earth and Planetary Sciences, McGill University, Montreal H3A 0E8, Canada;
- Institut de Ciència i Tecnologia Ambientals (ICTA-UAB), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
| | - Luke C Skinner
- Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom;
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17
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Marine nitrogen fixers mediate a low latitude pathway for atmospheric CO 2 drawdown. Nat Commun 2019; 10:4611. [PMID: 31601810 PMCID: PMC6787065 DOI: 10.1038/s41467-019-12549-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 09/16/2019] [Indexed: 02/02/2023] Open
Abstract
Roughly a third (~30 ppm) of the carbon dioxide (CO2) that entered the ocean during ice ages is attributed to biological mechanisms. A leading hypothesis for the biological drawdown of CO2 is iron (Fe) fertilisation of the high latitudes, but modelling efforts attribute at most 10 ppm to this mechanism, leaving ~20 ppm unexplained. We show that an Fe-induced stimulation of dinitrogen (N2) fixation can induce a low latitude drawdown of 7–16 ppm CO2. This mechanism involves a closer coupling between N2 fixers and denitrifiers that alleviates widespread nitrate limitation. Consequently, phosphate utilisation and carbon export increase near upwelling zones, causing deoxygenation and deeper carbon injection. Furthermore, this low latitude mechanism reproduces the regional patterns of organic δ15N deposited in glacial sediments. The positive response of marine N2 fixation to dusty ice age conditions, first proposed twenty years ago, therefore compliments high latitude changes to amplify CO2 drawdown. Iron fertilisation of the high latitude oceans is a well-established biological mechanism to explain the ice age drawdown of atmospheric CO2, yet modelling has so far struggled to account for a sufficient drawdown via this mechanism. Here, the authors propose that N2 fixers, which inhabit the lower latitude ocean, made a significant contribution to CO2 drawdown and so amplified the global response to iron fertilisation during ice ages.
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18
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Homogeneous sulfur isotope signature in East Antarctica and implication for sulfur source shifts through the last glacial-interglacial cycle. Sci Rep 2019; 9:12378. [PMID: 31455786 PMCID: PMC6711983 DOI: 10.1038/s41598-019-48801-1] [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: 06/10/2019] [Accepted: 08/08/2019] [Indexed: 11/09/2022] Open
Abstract
Sulfate aerosol (SO42-) preserved in Antarctic ice cores is discussed in the light of interactions between marine biological activity and climate since it is mainly sourced from biogenic emissions from the surface ocean and scatters solar radiation during traveling in the atmosphere. However, there has been a paradox between the ice core record and the marine sediment record; the former shows constant non-sea-salt (nss-) SO42- flux throughout the glacial-interglacial changes, and the latter shows a decrease in biogenic productivity during glacial periods compared to interglacial periods. Here, by ensuring the homogeneity of sulfur isotopic compositions of atmospheric nss-SO42- (δ34Snss) over East Antarctica, we established the applicability of the signature as a robust tool for distinguishing marine biogenic and nonmarine biogenic SO42-. Our findings, in conjunction with existing records of nss-SO42- flux and δ34Snss in Antarctic ice cores, provide an estimate of the relative importance of marine biogenic SO42- during the last glacial period to be 48 ± 10% of nss-SO42-, slightly lower than 59 ± 11% during the interglacial periods. Thus, our results tend to reconcile the ice core and sediment records, with both suggesting the decrease in marine productivity around Southern Ocean under the cold climate.
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19
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Wadham JL, Hawkings JR, Tarasov L, Gregoire LJ, Spencer RGM, Gutjahr M, Ridgwell A, Kohfeld KE. Ice sheets matter for the global carbon cycle. Nat Commun 2019; 10:3567. [PMID: 31417076 PMCID: PMC6695407 DOI: 10.1038/s41467-019-11394-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 07/09/2019] [Indexed: 11/09/2022] Open
Abstract
The cycling of carbon on Earth exerts a fundamental influence upon the greenhouse gas content of the atmosphere, and hence global climate over millennia. Until recently, ice sheets were viewed as inert components of this cycle and largely disregarded in global models. Research in the past decade has transformed this view, demonstrating the existence of uniquely adapted microbial communities, high rates of biogeochemical/physical weathering in ice sheets and storage and cycling of organic carbon (>104 Pg C) and nutrients. Here we assess the active role of ice sheets in the global carbon cycle and potential ramifications of enhanced melt and ice discharge in a warming world.
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Affiliation(s)
- J L Wadham
- University of Bristol, Bristol, BS8 1TH, UK.
| | - J R Hawkings
- National High Magnetic Field Lab and Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, 32306, USA
- German Research Centre for Geosciences GFZ, 14473, Potsdam, Germany
| | - L Tarasov
- Memorial University, St. John's, NF, A1B 3X9, Canada
| | | | - R G M Spencer
- National High Magnetic Field Lab and Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, 32306, USA
| | | | - A Ridgwell
- University of California, Riverside, CA, 94720, USA
| | - K E Kohfeld
- Simon Fraser University, Burnaby, BC, 8888, Canada
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20
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Khatiwala S, Schmittner A, Muglia J. Air-sea disequilibrium enhances ocean carbon storage during glacial periods. SCIENCE ADVANCES 2019; 5:eaaw4981. [PMID: 31206024 PMCID: PMC6561735 DOI: 10.1126/sciadv.aaw4981] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 05/09/2019] [Indexed: 06/09/2023]
Abstract
The prevailing hypothesis for lower atmospheric carbon dioxide (CO2) concentrations during glacial periods is an increased efficiency of the ocean's biological pump. However, tests of this and other hypotheses have been hampered by the difficulty to accurately quantify ocean carbon components. Here, we use an observationally constrained earth system model to precisely quantify these components and the role that different processes play in simulated glacial-interglacial CO2 variations. We find that air-sea disequilibrium greatly amplifies the effects of cooler temperatures and iron fertilization on glacial ocean carbon storage even as the efficiency of the soft-tissue biological pump decreases. These two processes, which have previously been regarded as minor, explain most of our simulated glacial CO2 drawdown, while ocean circulation and sea ice extent, hitherto considered dominant, emerge as relatively small contributors.
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Affiliation(s)
- S. Khatiwala
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - A. Schmittner
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - J. Muglia
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
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21
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Enhanced ocean-atmosphere carbon partitioning via the carbonate counter pump during the last deglacial. Nat Commun 2018; 9:2396. [PMID: 29921874 PMCID: PMC6008475 DOI: 10.1038/s41467-018-04625-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 05/08/2018] [Indexed: 11/18/2022] Open
Abstract
Several synergistic mechanisms were likely involved in the last deglacial atmospheric pCO2 rise. Leading hypotheses invoke a release of deep-ocean carbon through enhanced convection in the Southern Ocean (SO) and concomitant decreased efficiency of the global soft-tissue pump (STP). However, the temporal evolution of both the STP and the carbonate counter pump (CCP) remains unclear, thus preventing the evaluation of their contributions to the pCO2 rise. Here we present sedimentary coccolith records combined with export production reconstructions from the Subantarctic Pacific to document the leverage the SO biological carbon pump (BCP) has imposed on deglacial pCO2. Our data suggest a weakening of BCP during the phases of carbon outgassing, due in part to an increased CCP along with higher surface ocean fertility and elevated [CO2aq]. We propose that reduced BCP efficiency combined with enhanced SO ventilation played a major role in propelling the Earth out of the last ice age. The contribution of the carbonate counter pump (CCP) to the last deglacial atmospheric CO2 rise has yet been largely ignored. Here, the authors show that an increased CCP in the Subantarctic Pacific along with high surface ocean fertility and [CO2aq], contributed in propelling the Earth out of the last ice age.
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22
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Pecl GT, Araújo MB, Bell JD, Blanchard J, Bonebrake TC, Chen IC, Clark TD, Colwell RK, Danielsen F, Evengård B, Falconi L, Ferrier S, Frusher S, Garcia RA, Griffis RB, Hobday AJ, Janion-Scheepers C, Jarzyna MA, Jennings S, Lenoir J, Linnetved HI, Martin VY, McCormack PC, McDonald J, Mitchell NJ, Mustonen T, Pandolfi JM, Pettorelli N, Popova E, Robinson SA, Scheffers BR, Shaw JD, Sorte CJB, Strugnell JM, Sunday JM, Tuanmu MN, Vergés A, Villanueva C, Wernberg T, Wapstra E, Williams SE. Biodiversity redistribution under climate change: Impacts on ecosystems and human well-being. Science 2017; 355:355/6332/eaai9214. [PMID: 28360268 DOI: 10.1126/science.aai9214] [Citation(s) in RCA: 958] [Impact Index Per Article: 136.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Distributions of Earth's species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to global scales affects ecosystem functioning, human well-being, and the dynamics of climate change itself. Production of natural resources required for food security, patterns of disease transmission, and processes of carbon sequestration are all altered by changes in species distribution. Consideration of these effects of biodiversity redistribution is critical yet lacking in most mitigation and adaptation strategies, including the United Nation's Sustainable Development Goals.
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Affiliation(s)
- Gretta T Pecl
- Institute for Marine and Antarctic Studies, Hobart, Tasmania 7001, Australia. .,Centre for Marine Socioecology, Hobart, Tasmania 7001, Australia
| | - Miguel B Araújo
- Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain.,Centro de Investigação em Biodiversidade e Recursos Geneticos, Universidade de Évora, 7000-890 Évora, Portugal.,Department of Biology, Center for Macroecology, Evolution and Climate, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen O, Denmark
| | - Johann D Bell
- Australian National Centre for Ocean Resources and Security, University of Wollongong, New South Wales 2522, Australia.,Betty and Gordon Moore Center for Science and Oceans, Conservation International, Arlington, VA 22202, USA
| | - Julia Blanchard
- Institute for Marine and Antarctic Studies, Hobart, Tasmania 7001, Australia.,Centre for Marine Socioecology, Hobart, Tasmania 7001, Australia
| | - Timothy C Bonebrake
- School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - I-Ching Chen
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan, Republic of China
| | - Timothy D Clark
- Institute for Marine and Antarctic Studies, Hobart, Tasmania 7001, Australia.,Commonwealth Scientific and Industrial Research Organization (CSIRO) Agriculture and Food, Hobart, Tasmania 7000, Australia
| | - Robert K Colwell
- Department of Biology, Center for Macroecology, Evolution and Climate, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen O, Denmark.,Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA.,University of Colorado Museum of Natural History, Boulder, CO 80309, USA.,Departmento de Ecologia, Universidade Federal de Goiás, CP 131, 74.001-970 Goiânia, Goiás, Brazil
| | | | - Birgitta Evengård
- Division of Infectious Diseases, Department of Clinical Microbiology, Umea University, 90187 Umea, Sweden
| | - Lorena Falconi
- College of Marine and Environmental Science, James Cook University, Townsville, Queensland 4811, Australia
| | - Simon Ferrier
- CSIRO Land and Water, Canberra, Australian Capital Territory 2601, Australia
| | - Stewart Frusher
- Institute for Marine and Antarctic Studies, Hobart, Tasmania 7001, Australia.,Centre for Marine Socioecology, Hobart, Tasmania 7001, Australia
| | - Raquel A Garcia
- Centre for Statistics in Ecology, the Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Rondebosch 7701, Cape Town, South Africa.,Centre for Invasion Biology, Department of Botany and Zoology, Faculty of Science, Stellenbosch University, Matieland 7602, South Africa
| | - Roger B Griffis
- National Oceanic and Atmospheric Administration (NOAA) Fisheries Service, Silver Spring, MD 20912, USA
| | - Alistair J Hobday
- Centre for Marine Socioecology, Hobart, Tasmania 7001, Australia.,CSIRO Oceans and Atmosphere, Hobart, Tasmania 7000, Australia
| | | | - Marta A Jarzyna
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA
| | - Sarah Jennings
- Centre for Marine Socioecology, Hobart, Tasmania 7001, Australia.,Tasmanian School of Business and Economics, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Jonathan Lenoir
- EDYSAN (FRE 3498 CNRS-UPJV), Université de Picardie Jules Verne, 80037 Amiens Cedex 1, France
| | - Hlif I Linnetved
- Institute of Food and Resource Economics, Faculty of Science, University of Copenhagen, Rolighedsvej 25, DK-1958 Frederiksberg C, Denmark
| | - Victoria Y Martin
- School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales 2480, Australia
| | | | - Jan McDonald
- Centre for Marine Socioecology, Hobart, Tasmania 7001, Australia.,Faculty of Law, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Nicola J Mitchell
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Tero Mustonen
- Snowchange Cooperative, University of Eastern Finland, Joensuu, FIN 80100 Finland
| | - John M Pandolfi
- School of Biological Sciences, Autralian Research Council (ARC) Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nathalie Pettorelli
- Institute of Zoology, Zoological Society of London, Regent's Park, NW1 4RY London, UK
| | - Ekaterina Popova
- National Oceanography Centre, University of Southampton Waterfront Campus, European Way, Southampton, SO14 3ZH, UK
| | - Sharon A Robinson
- Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Brett R Scheffers
- Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Justine D Shaw
- Centre for Biodiversity and Conservation Science, School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Cascade J B Sorte
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA
| | - Jan M Strugnell
- Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, 4811 Queensland, Australia.,Department of Ecology, Environment and Evolution, School of Life Sciences, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Jennifer M Sunday
- Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Mao-Ning Tuanmu
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan, Republic of China
| | - Adriana Vergés
- Centre for Marine Bio-Innovation and Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Cecilia Villanueva
- Institute for Marine and Antarctic Studies, Hobart, Tasmania 7001, Australia.,Centre for Marine Socioecology, Hobart, Tasmania 7001, Australia
| | - Thomas Wernberg
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia.,Oceans Institute, The University of Western Australia, Perth, Western Australia 6009, Australia
| | - Erik Wapstra
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Stephen E Williams
- College of Marine and Environmental Science, James Cook University, Townsville, Queensland 4811, Australia
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23
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Abstract
Atmospheric dust constitutes particles <100 μm, or deposits thereof (continental or marine); dust includes ‘loess,’ defined as continental aeolian silt (4–62.5 μm). Dust is well-known from Earth's near-time (mostly Quaternary) record, and recognized as a high-fidelity archive of climate, but remains under-recognized for deep time. Attributes such as thickness, grain size, magnetism, pedogenesis, and provenance of dust form valuable indicators of paleoclimate to constrain models of atmospheric dustiness. Additionally, dust acts as an agent of climate change via both direct and indirect effects on radiative forcing, and on productivity, and thus the biosphere and carbon cycling. Dust from the late Paleozoic of western equatorial Pangea reflects ultimate derivation from orogens (ancestral Rocky Mountains, Central Pangean Mountains), whereas dust from southwestern Pangea (Bolivia) reflects both proximal volcanism and crustal material. Records of dust conducive to cyclostratigraphic analysis, such as data on dust inputs from carbonate sections, or magnetism in paleo-loess, reveal dust cyclicity at Milankovitch timescales, but resolution is compromised if records are too brief, or irregular in interval or magnitude of the attribute being measured. Climate modeling enables identification of the primary regions of dust sourcing in deep time, and impacts of dust on radiative balance and biogeochemistry. Deep-time modeling remains preliminary, but is achievable, and indicates principal dust sources in the Pangean subtropics, with sources increasing during colder climates. Carbon cycle modeling suggests that glacial-phase dust increases stimulated extreme productivity, potentially increasing algal activity and perturbing ecosystem compositions of the late Paleozoic.
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24
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Deep-sea coral evidence for lower Southern Ocean surface nitrate concentrations during the last ice age. Proc Natl Acad Sci U S A 2017; 114:3352-3357. [PMID: 28298529 DOI: 10.1073/pnas.1615718114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Southern Ocean regulates the ocean's biological sequestration of CO2 and is widely suspected to underpin much of the ice age decline in atmospheric CO2 concentration, but the specific changes in the region are debated. Although more complete drawdown of surface nutrients by phytoplankton during the ice ages is supported by some sediment core-based measurements, the use of different proxies in different regions has precluded a unified view of Southern Ocean biogeochemical change. Here, we report measurements of the 15N/14N of fossil-bound organic matter in the stony deep-sea coral Desmophyllum dianthus, a tool for reconstructing surface ocean nutrient conditions. The central robust observation is of higher 15N/14N across the Southern Ocean during the Last Glacial Maximum (LGM), 18-25 thousand years ago. These data suggest a reduced summer surface nitrate concentration in both the Antarctic and Subantarctic Zones during the LGM, with little surface nitrate transport between them. After the ice age, the increase in Antarctic surface nitrate occurred through the deglaciation and continued in the Holocene. The rise in Subantarctic surface nitrate appears to have had both early deglacial and late deglacial/Holocene components, preliminarily attributed to the end of Subantarctic iron fertilization and increasing nitrate input from the surface Antarctic Zone, respectively.
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25
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Conway TM, Hoffmann LJ, Breitbarth E, Strzepek RF, Wolff EW. The Growth Response of Two Diatom Species to Atmospheric Dust from the Last Glacial Maximum. PLoS One 2016; 11:e0158553. [PMID: 27384948 PMCID: PMC4934930 DOI: 10.1371/journal.pone.0158553] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/19/2016] [Indexed: 11/19/2022] Open
Abstract
Relief of iron (Fe) limitation in the surface Southern Ocean has been suggested as one driver of the regular glacial-interglacial cycles in atmospheric carbon dioxide (CO2). The proposed cause is enhanced deposition of Fe-bearing atmospheric dust to the oceans during glacial intervals, with consequent effects on export production and the carbon cycle. However, understanding the role of enhanced atmospheric Fe supply in biogeochemical cycles is limited by knowledge of the fluxes and ‘bioavailability’ of atmospheric Fe during glacial intervals. Here, we assess the effect of Fe fertilization by dust, dry-extracted from the Last Glacial Maximum portion of the EPICA Dome C Antarctic ice core, on the Antarctic diatom species Eucampia antarctica and Proboscia inermis. Both species showed strong but differing reactions to dust addition. E. antarctica increased cell number (3880 vs. 786 cells mL-1), chlorophyll a (51 vs. 3.9 μg mL-1) and particulate organic carbon (POC; 1.68 vs. 0.28 μg mL-1) production in response to dust compared to controls. P. inermis did not increase cell number in response to dust, but chlorophyll a and POC per cell both strongly increased compared to controls (39 vs. 15 and 2.13 vs. 0.95 ng cell-1 respectively). The net result of both responses was a greater production of POC and chlorophyll a, as well as decreased Si:C and Si:N incorporation ratios within cells. However, E, antarctica decreased silicate uptake for the same nitrate and carbon uptake, while P. inermis increased carbon and nitrate uptake for the same silicate uptake. This suggests that nutrient utilization changes in response to Fe addition could be driven by different underlying mechanisms between different diatom species. Enhanced supply of atmospheric dust to the surface ocean during glacial intervals could therefore have driven nutrient-utilization changes which could permit greater carbon fixation for lower silica utilization. Additionally, both species responded more strongly to lower amounts of direct Fe chloride addition than they did to dust, suggesting that not all the Fe released from dust was in a bioavailable form available for uptake by diatoms.
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Affiliation(s)
- Tim M. Conway
- British Antarctic Survey, Cambridge, United Kingdom
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
- Department of Earth Sciences, ETH Zürich, Zürich, Switzerland
- * E-mail:
| | - Linn J. Hoffmann
- Department of Chemistry, University of Otago, Dunedin, New Zealand
| | - Eike Breitbarth
- Department of Chemistry, University of Otago, Dunedin, New Zealand
| | | | - Eric W. Wolff
- British Antarctic Survey, Cambridge, United Kingdom
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
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26
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Howe JNW, Piotrowski AM, Noble TL, Mulitza S, Chiessi CM, Bayon G. North Atlantic Deep Water Production during the Last Glacial Maximum. Nat Commun 2016; 7:11765. [PMID: 27256826 PMCID: PMC4895795 DOI: 10.1038/ncomms11765] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/27/2016] [Indexed: 11/16/2022] Open
Abstract
Changes in deep ocean ventilation are commonly invoked as the primary cause of lower glacial atmospheric CO2. The water mass structure of the glacial deep Atlantic Ocean and the mechanism by which it may have sequestered carbon remain elusive. Here we present neodymium isotope measurements from cores throughout the Atlantic that reveal glacial–interglacial changes in water mass distributions. These results demonstrate the sustained production of North Atlantic Deep Water under glacial conditions, indicating that southern-sourced waters were not as spatially extensive during the Last Glacial Maximum as previously believed. We demonstrate that the depleted glacial δ13C values in the deep Atlantic Ocean cannot be explained solely by water mass source changes. A greater amount of respired carbon, therefore, must have been stored in the abyssal Atlantic during the Last Glacial Maximum. We infer that this was achieved by a sluggish deep overturning cell, comprised of well-mixed northern- and southern-sourced waters. The nature of the overturning circulation in the Atlantic Ocean during the Last Glacial Maximum remains a topic of contention. Here, using neodymium isotope measurements, the authors demonstrate that North Atlantic Deep Water was produced under glacial climate conditions.
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Affiliation(s)
- Jacob N W Howe
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
| | | | - Taryn L Noble
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK.,Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Stefan Mulitza
- MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, D-28359 Bremen, Germany
| | - Cristiano M Chiessi
- School of Arts, Sciences and Humanities, University of São Paulo, Av. Arlindo Bettio 1000, CEP03828-000 São Paulo SP, Brazil
| | - Germain Bayon
- Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Unité de Recherche Géosciences Marines, F-29280 Plouzané, France
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Younger JL, van den Hoff J, Wienecke B, Hindell M, Miller KJ. Contrasting responses to a climate regime change by sympatric, ice-dependent predators. BMC Evol Biol 2016; 16:61. [PMID: 26975876 PMCID: PMC5477764 DOI: 10.1186/s12862-016-0630-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/01/2016] [Indexed: 02/02/2023] Open
Abstract
Background Models that predict changes in the abundance and distribution of fauna under future climate change scenarios often assume that ecological niche and habitat availability are the major determinants of species’ responses to climate change. However, individual species may have very different capacities to adapt to environmental change, as determined by intrinsic factors such as their dispersal ability, genetic diversity, generation time and rate of evolution. These intrinsic factors are usually excluded from forecasts of species’ abundance and distribution changes. We aimed to determine the importance of these factors by comparing the impact of the most recent climate regime change, the late Pleistocene glacial-interglacial transition, on two sympatric, ice-dependent meso-predators, the emperor penguin (Aptenodytes forsteri) and Weddell seal (Leptonychotes weddellii). Methods We reconstructed the population trend of emperor penguins and Weddell seals in East Antarctica over the past 75,000 years using mitochondrial DNA sequences and an extended Bayesian skyline plot method. We also assessed patterns of contemporary population structure and genetic diversity. Results Despite their overlapping distributions and shared dependence on sea ice, our genetic data revealed very different responses to climate warming between these species. The emperor penguin population grew rapidly following the glacial-interglacial transition, but the size of the Weddell seal population did not change. The expansion of emperor penguin numbers during the warm Holocene may have been facilitated by their higher dispersal ability and gene flow among colonies, and fine-scale differences in preferred foraging locations. Conclusions The vastly different climate change responses of two sympatric ice-dependent predators suggests that differing adaptive capacities and/or fine-scale niche differences can play a major role in species’ climate change responses, and that adaptive capacity should be considered alongside niche and distribution in future species forecasts. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0630-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jane L Younger
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, 7001, Tasmania, Australia.
| | - John van den Hoff
- Australian Antarctic Division, 203 Channel Highway, Kingston, 7050, Tasmania, Australia
| | - Barbara Wienecke
- Australian Antarctic Division, 203 Channel Highway, Kingston, 7050, Tasmania, Australia
| | - Mark Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, 7001, Tasmania, Australia
| | - Karen J Miller
- Australian Institute of Marine Science, The UWA Oceans Institute, 35 Stirling Highway, Crawley, WA, 6009, Australia.,School of Biological Sciences, Private Bag 5, University of Tasmania, Hobart, 7001, Tasmania, Australia
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Cartapanis O, Bianchi D, Jaccard SL, Galbraith ED. Global pulses of organic carbon burial in deep-sea sediments during glacial maxima. Nat Commun 2016; 7:10796. [PMID: 26923945 PMCID: PMC4773493 DOI: 10.1038/ncomms10796] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 01/21/2016] [Indexed: 12/02/2022] Open
Abstract
The burial of organic carbon in marine sediments removes carbon dioxide from the ocean–atmosphere pool, provides energy to the deep biosphere, and on geological timescales drives the oxygenation of the atmosphere. Here we quantify natural variations in the burial of organic carbon in deep-sea sediments over the last glacial cycle. Using a new data compilation of hundreds of sediment cores, we show that the accumulation rate of organic carbon in the deep sea was consistently higher (50%) during glacial maxima than during interglacials. The spatial pattern and temporal progression of the changes suggest that enhanced nutrient supply to parts of the surface ocean contributed to the glacial burial pulses, with likely additional contributions from more efficient transfer of organic matter to the deep sea and better preservation of organic matter due to reduced oxygen exposure. These results demonstrate a pronounced climate sensitivity for this global carbon cycle sink. While numerous studies have indicated that carbon export to the deep ocean was greater during glacial periods, quantification is lacking. Here, via analysis of hundreds of sediment cores, the authors show carbon accumulation rate was 50% higher during glacial maxima than during interglacials.
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Affiliation(s)
- Olivier Cartapanis
- Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland.,Department of Earth and Planetary Sciences, McGill University, Montreal, Canada H3A 2A7
| | - Daniele Bianchi
- Department of Earth and Planetary Sciences, McGill University, Montreal, Canada H3A 2A7.,School of Oceanography, University of Washington, Seattle, Washington 98105, USA.,Department of Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, California 90095-1565, USA
| | - Samuel L Jaccard
- Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
| | - Eric D Galbraith
- Department of Earth and Planetary Sciences, McGill University, Montreal, Canada H3A 2A7.,Institució Catalana de Recerca i Estudis Avancats (ICREA), 08010 Barcelona, Spain.,Institut de Ciència i Tecnologia Ambientals and Department of Mathematics, Universitat Autonoma de Barcelona, 08193 Barcelona, Spain
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Covariation of deep Southern Ocean oxygenation and atmospheric CO2 through the last ice age. Nature 2016; 530:207-10. [DOI: 10.1038/nature16514] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 11/27/2015] [Indexed: 11/09/2022]
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Younger JL, Emmerson LM, Miller KJ. The influence of historical climate changes on Southern Ocean marine predator populations: a comparative analysis. GLOBAL CHANGE BIOLOGY 2016; 22:474-93. [PMID: 26391440 DOI: 10.1111/gcb.13104] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Revised: 08/17/2015] [Accepted: 08/18/2015] [Indexed: 05/28/2023]
Abstract
The Southern Ocean ecosystem is undergoing rapid physical and biological changes that are likely to have profound implications for higher-order predators. Here, we compare the long-term, historical responses of Southern Ocean predators to climate change. We examine palaeoecological evidence for changes in the abundance and distribution of seabirds and marine mammals, and place these into context with palaeoclimate records in order to identify key environmental drivers associated with population changes. Our synthesis revealed two key factors underlying Southern Ocean predator population changes; (i) the availability of ice-free ground for breeding and (ii) access to productive foraging grounds. The processes of glaciation and sea ice fluctuation were key; the distributions and abundances of elephant seals, snow petrels, gentoo, chinstrap and Adélie penguins all responded strongly to the emergence of new breeding habitat coincident with deglaciation and reductions in sea ice. Access to productive foraging grounds was another limiting factor, with snow petrels, king and emperor penguins all affected by reduced prey availability in the past. Several species were isolated in glacial refugia and there is evidence that refuge populations were supported by polynyas. While the underlying drivers of population change were similar across most Southern Ocean predators, the individual responses of species to environmental change varied because of species specific factors such as dispersal ability and environmental sensitivity. Such interspecific differences are likely to affect the future climate change responses of Southern Ocean marine predators and should be considered in conservation plans. Comparative palaeoecological studies are a valuable source of long-term data on species' responses to environmental change that can provide important insights into future climate change responses. This synthesis highlights the importance of protecting productive foraging grounds proximate to breeding locations, as well as the potential role of polynyas as future Southern Ocean refugia.
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Affiliation(s)
- Jane L Younger
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, 7001, Tas., Australia
| | - Louise M Emmerson
- Australian Antarctic Division, 203 Channel Highway, Kingston, 7050, Tas., Australia
| | - Karen J Miller
- Australian Institute of Marine Science, The UWA Oceans Institute, 35 Stirling Highway, Crawley, WA, 6009, Australia
- School of Biological Sciences, University of Tasmania, Private Bag 5, Hobart, 7001, Tas., Australia
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Younger J, Emmerson L, Southwell C, Lelliott P, Miller K. Proliferation of East Antarctic Adélie penguins in response to historical deglaciation. BMC Evol Biol 2015; 15:236. [PMID: 26577544 PMCID: PMC4650495 DOI: 10.1186/s12862-015-0502-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/30/2015] [Indexed: 01/27/2023] Open
Abstract
Background Major, long-term environmental changes are projected in the Southern Ocean and these are likely to have impacts for marine predators such as the Adélie penguin (Pygoscelis adeliae). Decadal monitoring studies have provided insight into the short-term environmental sensitivities of Adélie penguin populations, particularly to sea ice changes. However, given the long-term nature of projected climate change, it is also prudent to consider the responses of populations to environmental change over longer time scales. We investigated the population trajectory of Adélie penguins during the last glacial-interglacial transition to determine how the species was affected by climate warming over millennia. We focussed our study on East Antarctica, which is home to 30 % of the global population of Adélie penguins. Methods Using mitochondrial DNA from extant colonies, we reconstructed the population trend of Adélie penguins in East Antarctica over the past 22,000 years using an extended Bayesian skyline plot method. To determine the relationship of East Antarctic Adélie penguins with populations elsewhere in Antarctica we constructed a phylogeny using mitochondrial DNA sequences. Results We found that the Adélie penguin population expanded 135-fold from approximately 14,000 years ago. The population growth was coincident with deglaciation in East Antarctica and, therefore, an increase in ice-free ground suitable for Adélie penguin nesting. Our phylogenetic analysis indicated that East Antarctic Adélie penguins share a common ancestor with Adélie penguins from the Antarctic Peninsula and Scotia Arc, with an estimated age of 29,000 years ago, in the midst of the last glacial period. This finding suggests that extant colonies in East Antarctica, the Scotia Arc and the Antarctic Peninsula were founded from a single glacial refuge. Conclusions While changes in sea ice conditions are a critical driver of Adélie penguin population success over decadal and yearly timescales, deglaciation appears to have been the key driver of population change over millennia. This suggests that environmental drivers of population trends over thousands of years may differ to drivers over years or decades, highlighting the need to consider millennial-scale trends alongside contemporary data for the forecasting of species’ abundance and distribution changes under future climate change scenarios.
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Affiliation(s)
- Jane Younger
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, 7001, TAS, Australia. .,Australian School of Advanced Medicine, Macquarie University, 2 Technology Place, 2109, NSW, Sydney, Australia.
| | - Louise Emmerson
- Australian Antarctic Division, 203 Channel Highway, Kingston, 7050, TAS, Australia.
| | - Colin Southwell
- Australian Antarctic Division, 203 Channel Highway, Kingston, 7050, TAS, Australia.
| | - Patrick Lelliott
- Australian School of Advanced Medicine, Macquarie University, 2 Technology Place, 2109, NSW, Sydney, Australia. .,John Curtin School of Medical Research, Australian National University, 131 Garran Road, Acton, 2601, ACT, Australia.
| | - Karen Miller
- Australian Institute of Marine Science, The UWA Oceans Institute, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia. .,School of Biological Sciences, Private Bag 5, University of Tasmania, Hobart, 7001, TAS, Australia.
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Younger JL, Clucas GV, Kooyman G, Wienecke B, Rogers AD, Trathan PN, Hart T, Miller KJ. Too much of a good thing: sea ice extent may have forced emperor penguins into refugia during the last glacial maximum. GLOBAL CHANGE BIOLOGY 2015; 21:2215-26. [PMID: 25728986 DOI: 10.1111/gcb.12882] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/13/2014] [Accepted: 12/30/2014] [Indexed: 05/12/2023]
Abstract
The relationship between population structure and demographic history is critical to understanding microevolution and for predicting the resilience of species to environmental change. Using mitochondrial DNA from extant colonies and radiocarbon-dated subfossils, we present the first microevolutionary analysis of emperor penguins (Aptenodytes forsteri) and show their population trends throughout the last glacial maximum (LGM, 19.5-16 kya) and during the subsequent period of warming and sea ice retreat. We found evidence for three mitochondrial clades within emperor penguins, suggesting that they were isolated within three glacial refugia during the LGM. One of these clades has remained largely isolated within the Ross Sea, while the two other clades have intermixed around the coast of Antarctica from Adélie Land to the Weddell Sea. The differentiation of the Ross Sea population has been preserved despite rapid population growth and opportunities for migration. Low effective population sizes during the LGM, followed by a rapid expansion around the beginning of the Holocene, suggest that an optimum set of sea ice conditions exist for emperor penguins, corresponding to available foraging area.
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Affiliation(s)
- Jane L Younger
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, 7001, Tas., Australia; Australian School of Advanced Medicine, Macquarie University, 2 Technology Place, Sydney, 2109, NSW, Australia
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Climate change decouples oceanic primary and export productivity and organic carbon burial. Proc Natl Acad Sci U S A 2015; 112:332-5. [PMID: 25453073 DOI: 10.1073/pnas.1410480111] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding responses of oceanic primary productivity, carbon export, and burial to climate change is essential for model-based projection of biological feedbacks in a high-CO2 world. Here we compare estimates of productivity based on the composition of fossil diatom floras with organic carbon burial off Oregon in the Northeast Pacific across a large climatic transition at the last glacial termination. Although estimated primary productivity was highest during the Last Glacial Maximum, carbon burial was lowest, reflecting reduced preservation linked to low sedimentation rates. A diatom size index further points to a glacial decrease (and deglacial increase) in the fraction of fixed carbon that was exported, inferred to reflect expansion, and contraction, of subpolar ecosystems that today favor smaller plankton. Thus, in contrast to models that link remineralization of carbon to temperature, in the Northeast Pacific, we find dominant ecosystem and sea floor control such that intervals of warming climate had more efficient carbon export and higher carbon burial despite falling primary productivity.
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Martínez-García A, Sigman DM, Ren H, Anderson RF, Straub M, Hodell DA, Jaccard SL, Eglinton TI, Haug GH. Iron fertilization of the Subantarctic ocean during the last ice age. Science 2014; 343:1347-50. [PMID: 24653031 DOI: 10.1126/science.1246848] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
John H. Martin, who discovered widespread iron limitation of ocean productivity, proposed that dust-borne iron fertilization of Southern Ocean phytoplankton caused the ice age reduction in atmospheric carbon dioxide (CO2). In a sediment core from the Subantarctic Atlantic, we measured foraminifera-bound nitrogen isotopes to reconstruct ice age nitrate consumption, burial fluxes of iron, and proxies for productivity. Peak glacial times and millennial cold events are characterized by increases in dust flux, productivity, and the degree of nitrate consumption; this combination is uniquely consistent with Subantarctic iron fertilization. The associated strengthening of the Southern Ocean's biological pump can explain the lowering of CO2 at the transition from mid-climate states to full ice age conditions as well as the millennial-scale CO2 oscillations.
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Factors affecting the abundance and community structure of the phytoplankton in northern South China Sea in the summer of 2008: a biomarker study. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/s11434-013-0106-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ocean–Atmosphere Interactions of Particles. OCEAN-ATMOSPHERE INTERACTIONS OF GASES AND PARTICLES 2014. [DOI: 10.1007/978-3-642-25643-1_4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Jaccard SL, Hayes CT, Martínez-García A, Hodell DA, Anderson RF, Sigman DM, Haug GH. Two modes of change in Southern Ocean productivity over the past million years. Science 2013; 339:1419-23. [PMID: 23520109 DOI: 10.1126/science.1227545] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Export of organic carbon from surface waters of the Antarctic Zone of the Southern Ocean decreased during the last ice age, coinciding with declining atmospheric carbon dioxide (CO(2)) concentrations, signaling reduced exchange of CO(2) between the ocean interior and the atmosphere. In contrast, in the Subantarctic Zone, export production increased into ice ages coinciding with rising dust fluxes, thus suggesting iron fertilization of subantarctic phytoplankton. Here, a new high-resolution productivity record from the Antarctic Zone is compiled with parallel subantarctic data over the past million years. Together, they fit the view that the combination of these two modes of Southern Ocean change determines the temporal structure of the glacial-interglacial atmospheric CO(2) record, including during the interval of "lukewarm" interglacials between 450 and 800 thousand years ago.
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Affiliation(s)
- S L Jaccard
- Geological Institute, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland.
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Smith KL, Sherman AD, Shaw TJ, Sprintall J. Icebergs as unique Lagrangian ecosystems in polar seas. ANNUAL REVIEW OF MARINE SCIENCE 2012; 5:269-287. [PMID: 22809193 DOI: 10.1146/annurev-marine-121211-172317] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Global warming and its disproportionate impact on polar regions have led to increased iceberg populations. Southern Ocean studies in the northwest Weddell Sea have verified substantial delivery of terrestrial material accompanied by increased primary production and faunal abundance associated with free-drifting icebergs. It is hypothesized that input and utilization of macro- and micronutrients are promoted by conditions unique to free-drifting icebergs, leading to increased production, grazing, and export of organic carbon. In Arctic regions, increased freshwater input from meltwater acts to stratify and stabilize the upper water column. As has been observed in the Southern Ocean, Arctic-region icebergs should drive turbulent upwelling and reduce stratification, potentially leading to increased nitrate delivery to the local ecosystem. Increasing populations of icebergs in polar regions can potentially be important in mediating the drawdown and sequestration of CO(2) and can thus impact the oceanic carbon cycle.
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Affiliation(s)
- K L Smith
- Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA.
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Deep carbon export from a Southern Ocean iron-fertilized diatom bloom. Nature 2012; 487:313-9. [DOI: 10.1038/nature11229] [Citation(s) in RCA: 291] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 05/03/2012] [Indexed: 11/08/2022]
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Southern Ocean dust-climate coupling over the past four million years. Nature 2011; 476:312-5. [PMID: 21814203 DOI: 10.1038/nature10310] [Citation(s) in RCA: 248] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 06/16/2011] [Indexed: 11/08/2022]
Abstract
Dust has the potential to modify global climate by influencing the radiative balance of the atmosphere and by supplying iron and other essential limiting micronutrients to the ocean. Indeed, dust supply to the Southern Ocean increases during ice ages, and 'iron fertilization' of the subantarctic zone may have contributed up to 40 parts per million by volume (p.p.m.v.) of the decrease (80-100 p.p.m.v.) in atmospheric carbon dioxide observed during late Pleistocene glacial cycles. So far, however, the magnitude of Southern Ocean dust deposition in earlier times and its role in the development and evolution of Pleistocene glacial cycles have remained unclear. Here we report a high-resolution record of dust and iron supply to the Southern Ocean over the past four million years, derived from the analysis of marine sediments from ODP Site 1090, located in the Atlantic sector of the subantarctic zone. The close correspondence of our dust and iron deposition records with Antarctic ice core reconstructions of dust flux covering the past 800,000 years (refs 8, 9) indicates that both of these archives record large-scale deposition changes that should apply to most of the Southern Ocean, validating previous interpretations of the ice core data. The extension of the record beyond the interval covered by the Antarctic ice cores reveals that, in contrast to the relatively gradual intensification of glacial cycles over the past three million years, Southern Ocean dust and iron flux rose sharply at the Mid-Pleistocene climatic transition around 1.25 million years ago. This finding complements previous observations over late Pleistocene glacial cycles, providing new evidence of a tight connection between high dust input to the Southern Ocean and the emergence of the deep glaciations that characterize the past one million years of Earth history.
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Prentice IC, Harrison SP, Bartlein PJ. Global vegetation and terrestrial carbon cycle changes after the last ice age. THE NEW PHYTOLOGIST 2011; 189:988-998. [PMID: 21288244 DOI: 10.1111/j.1469-8137.2010.03620.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
• In current models, the ecophysiological effects of CO₂ create both woody thickening and terrestrial carbon uptake, as observed now, and forest cover and terrestrial carbon storage increases that took place after the last glacial maximum (LGM). Here, we aimed to assess the realism of modelled vegetation and carbon storage changes between LGM and the pre-industrial Holocene (PIH). • We applied Land Processes and eXchanges (LPX), a dynamic global vegetation model (DGVM), with lowered CO₂ and LGM climate anomalies from the Palaeoclimate Modelling Intercomparison Project (PMIP II), and compared the model results with palaeodata. • Modelled global gross primary production was reduced by 27-36% and carbon storage by 550-694 Pg C compared with PIH. Comparable reductions have been estimated from stable isotopes. The modelled areal reduction of forests is broadly consistent with pollen records. Despite reduced productivity and biomass, tropical forests accounted for a greater proportion of modelled land carbon storage at LGM (28-32%) than at PIH (25%). • The agreement between palaeodata and model results for LGM is consistent with the hypothesis that the ecophysiological effects of CO₂ influence tree-grass competition and vegetation productivity, and suggests that these effects are also at work today.
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Affiliation(s)
- I C Prentice
- Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia
- Grantham Institute for Climate Change, and Division of Biology, Imperial College, Ascot SL5 7PY, UK
| | - S P Harrison
- Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia
- School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK
| | - P J Bartlein
- Department of Geography, University of Oregon, Eugene, OR 97403-1251, USA
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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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Sun X, Matsumoto K. Effects of sea ice on atmosphericpCO2: A revised view and implications for glacial and future climates. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jg001023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Xiaoting Sun
- Department of Geology and Geophysics; University of Minnesota; Minneapolis Minnesota USA
| | - Katsumi Matsumoto
- Department of Geology and Geophysics; University of Minnesota; Minneapolis Minnesota USA
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Marchetti A, Cassar N. Diatom elemental and morphological changes in response to iron limitation: a brief review with potential paleoceanographic applications. GEOBIOLOGY 2009; 7:419-431. [PMID: 19659798 DOI: 10.1111/j.1472-4669.2009.00207.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Diatoms are a major group of phytoplankton that account for approximately 40% of the ocean carbon fixation and the vast majority of biogenic silica production through the construction of their cell walls (termed frustules). These frustules accumulate and are partially preserved in the ocean sediments. Diatom growth and nutrient utilization in high-nitrate, low-chlorophyll regions of the world's oceans are mostly regulated by iron availability. Diatoms acclimate to iron limitation by decreasing cell size. The associated increase in surface area-to-volume ratio and decrease in diffusive boundary layer thickness may improve nutrient uptake kinetics. In parallel, cellular silicon (Si) contents are elevated in iron-limited diatoms relative to nitrogen (N) and carbon (C). Variations in degree of silicification and nutritional requirements of iron-limited diatoms have been hypothesized to account for higher cellular Si and/or lower cellular N and C, respectively. However, in some diatoms, frustule silicification does not significantly change when cells are iron-limited. Instead, changes in the Si-containing valve surface area relative to volume within these diatoms is hypothesized to be responsible for the variations in the cellular Si : N and Si : C ratios. In particular, some examined iron-limited pennate diatoms have reduced widths relative to their lengths (i.e. lower length-normalized widths, LNW) compared to iron-replete cells. In the pennate diatom Fragilariopsis kerguelensis, the mean LNWs of valves preserved in sediments throughout the Southern Ocean (a well-characterized iron-limited region) is positively correlated with satellite-derived, climatological net primary productivity in the overlying waters. Because of the specific morphological changes in pennate diatom frustules in response to iron availability, the valve morphometerics (e.g. LNWs) can potentially be used as a diagnostic tool for iron-limited diatom growth and relative changes in the Si : N (and Si : C) ratios in extant diatom assemblages as well as those preserved in the sediments.
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Affiliation(s)
- A Marchetti
- School of Oceanography, University of Washington, Seattle, WA, USA.
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Pollard RT, Salter I, Sanders RJ, Lucas MI, Moore CM, Mills RA, Statham PJ, Allen JT, Baker AR, Bakker DCE, Charette MA, Fielding S, Fones GR, French M, Hickman AE, Holland RJ, Hughes JA, Jickells TD, Lampitt RS, Morris PJ, Nédélec FH, Nielsdóttir M, Planquette H, Popova EE, Poulton AJ, Read JF, Seeyave S, Smith T, Stinchcombe M, Taylor S, Thomalla S, Venables HJ, Williamson R, Zubkov MV. Southern Ocean deep-water carbon export enhanced by natural iron fertilization. Nature 2009; 457:577-80. [PMID: 19177128 DOI: 10.1038/nature07716] [Citation(s) in RCA: 292] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Accepted: 12/08/2008] [Indexed: 11/09/2022]
Abstract
The addition of iron to high-nutrient, low-chlorophyll regions induces phytoplankton blooms that take up carbon. Carbon export from the surface layer and, in particular, the ability of the ocean and sediments to sequester carbon for many years remains, however, poorly quantified. Here we report data from the CROZEX experiment in the Southern Ocean, which was conducted to test the hypothesis that the observed north-south gradient in phytoplankton concentrations in the vicinity of the Crozet Islands is induced by natural iron fertilization that results in enhanced organic carbon flux to the deep ocean. We report annual particulate carbon fluxes out of the surface layer, at three kilometres below the ocean surface and to the ocean floor. We find that carbon fluxes from a highly productive, naturally iron-fertilized region of the sub-Antarctic Southern Ocean are two to three times larger than the carbon fluxes from an adjacent high-nutrient, low-chlorophyll area not fertilized by iron. Our findings support the hypothesis that increased iron supply to the glacial sub-Antarctic may have directly enhanced carbon export to the deep ocean. The CROZEX sequestration efficiency (the amount of carbon sequestered below the depth of winter mixing for a given iron supply) of 8,600 mol mol(-1) was 18 times greater than that of a phytoplankton bloom induced artificially by adding iron, but 77 times smaller than that of another bloom initiated, like CROZEX, by a natural supply of iron. Large losses of purposefully added iron can explain the lower efficiency of the induced bloom(6). The discrepancy between the blooms naturally supplied with iron may result in part from an underestimate of horizontal iron supply.
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Affiliation(s)
- Raymond T Pollard
- National Oceanography Centre Southampton, Natural Environment Research Council and University of Southampton, European Way, Southampton SO14 3ZH, UK
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Abstract
Atmospheric aerosol deposition is an important source of nutrients and trace metals to the open ocean that can enhance ocean productivity and carbon sequestration and thus influence atmospheric carbon dioxide concentrations and climate. Using aerosol samples from different back trajectories in incubation experiments with natural communities, we demonstrate that the response of phytoplankton growth to aerosol additions depends on specific components in aerosols and differs across phytoplankton species. Aerosol additions enhanced growth by releasing nitrogen and phosphorus, but not all aerosols stimulated growth. Toxic effects were observed with some aerosols, where the toxicity affected picoeukaryotes and Synechococcus but not Prochlorococcus. We suggest that the toxicity could be due to high copper concentrations in these aerosols and support this by laboratory copper toxicity tests preformed with Synechococcus cultures. However, it is possible that other elements present in the aerosols or unknown synergistic effects between these elements could have also contributed to the toxic effect. Anthropogenic emissions are increasing atmospheric copper deposition sharply, and based on coupled atmosphere-ocean calculations, we show that this deposition can potentially alter patterns of marine primary production and community structure in high aerosol, low chlorophyll areas, particularly in the Bay of Bengal and downwind of South and East Asia.
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Reid PC, Fischer AC, Lewis-Brown E, Meredith MP, Sparrow M, Andersson AJ, Antia A, Bates NR, Bathmann U, Beaugrand G, Brix H, Dye S, Edwards M, Furevik T, Gangstø R, Hátún H, Hopcroft RR, Kendall M, Kasten S, Keeling R, Le Quéré C, Mackenzie FT, Malin G, Mauritzen C, Olafsson J, Paull C, Rignot E, Shimada K, Vogt M, Wallace C, Wang Z, Washington R. Chapter 1. Impacts of the oceans on climate change. ADVANCES IN MARINE BIOLOGY 2009; 56:1-150. [PMID: 19895974 DOI: 10.1016/s0065-2881(09)56001-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The oceans play a key role in climate regulation especially in part buffering (neutralising) the effects of increasing levels of greenhouse gases in the atmosphere and rising global temperatures. This chapter examines how the regulatory processes performed by the oceans alter as a response to climate change and assesses the extent to which positive feedbacks from the ocean may exacerbate climate change. There is clear evidence for rapid change in the oceans. As the main heat store for the world there has been an accelerating change in sea temperatures over the last few decades, which has contributed to rising sea-level. The oceans are also the main store of carbon dioxide (CO2), and are estimated to have taken up approximately 40% of anthropogenic-sourced CO2 from the atmosphere since the beginning of the industrial revolution. A proportion of the carbon uptake is exported via the four ocean 'carbon pumps' (Solubility, Biological, Continental Shelf and Carbonate Counter) to the deep ocean reservoir. Increases in sea temperature and changing planktonic systems and ocean currents may lead to a reduction in the uptake of CO2 by the ocean; some evidence suggests a suppression of parts of the marine carbon sink is already underway. While the oceans have buffered climate change through the uptake of CO2 produced by fossil fuel burning this has already had an impact on ocean chemistry through ocean acidification and will continue to do so. Feedbacks to climate change from acidification may result from expected impacts on marine organisms (especially corals and calcareous plankton), ecosystems and biogeochemical cycles. The polar regions of the world are showing the most rapid responses to climate change. As a result of a strong ice-ocean influence, small changes in temperature, salinity and ice cover may trigger large and sudden changes in regional climate with potential downstream feedbacks to the climate of the rest of the world. A warming Arctic Ocean may lead to further releases of the potent greenhouse gas methane from hydrates and permafrost. The Southern Ocean plays a critical role in driving, modifying and regulating global climate change via the carbon cycle and through its impact on adjacent Antarctica. The Antarctic Peninsula has shown some of the most rapid rises in atmospheric and oceanic temperature in the world, with an associated retreat of the majority of glaciers. Parts of the West Antarctic ice sheet are deflating rapidly, very likely due to a change in the flux of oceanic heat to the undersides of the floating ice shelves. The final section on modelling feedbacks from the ocean to climate change identifies limitations and priorities for model development and associated observations. Considering the importance of the oceans to climate change and our limited understanding of climate-related ocean processes, our ability to measure the changes that are taking place are conspicuously inadequate. The chapter highlights the need for a comprehensive, adequately funded and globally extensive ocean observing system to be implemented and sustained as a high priority. Unless feedbacks from the oceans to climate change are adequately included in climate change models, it is possible that the mitigation actions needed to stabilise CO2 and limit temperature rise over the next century will be underestimated.
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Affiliation(s)
- Philip C Reid
- Sir Alister Hardy Foundation for Ocean Science, The Laboratory, Citadel Hill, Plymouth PL1 2PB, United Kingdom
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Kohfeld KE, Ridgwell A. Glacial-interglacial variability in atmospheric CO2. SURFACE OCEAN—LOWER ATMOSPHERE PROCESSES 2009. [DOI: 10.1029/2008gm000845] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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