1
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Castagno AP, Wagner TJW, Cape MR, Lester CW, Bailey E, Alves-de-Souza C, York RA, Fleming AH. Increased sea ice melt as a driver of enhanced Arctic phytoplankton blooming. GLOBAL CHANGE BIOLOGY 2023; 29:5087-5098. [PMID: 37332145 DOI: 10.1111/gcb.16815] [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: 12/13/2022] [Revised: 03/25/2023] [Accepted: 05/21/2023] [Indexed: 06/20/2023]
Abstract
Phytoplankton primary production in the Arctic Ocean has been increasing over the last two decades. In 2019, a record spring bloom occurred in Fram Strait, characterized by a peak in chlorophyll that was reached weeks earlier than in other years and was larger than any previously recorded May bloom. Here, we consider the conditions that led to this event and examine drivers of spring phytoplankton blooms in Fram Strait using in situ, remote sensing, and data assimilation methods. From samples collected during the May 2019 bloom, we observe a direct relationship between sea ice meltwater in the upper water column and chlorophyll a pigment concentrations. We place the 2019 spring dynamics in context of the past 20 years, a period marked by rapid change in climatic conditions. Our findings suggest that increased advection of sea ice into the region and warmer surface temperatures led to a rise in meltwater input and stronger near-surface stratification. Over this time period, we identify large-scale spatial correlations in Fram Strait between increased chlorophyll a concentrations and increased freshwater flux from sea ice melt.
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Affiliation(s)
- Andrew P Castagno
- University of North Carolina Wilmington, Wilmington, North Carolina, USA
| | - Till J W Wagner
- University of North Carolina Wilmington, Wilmington, North Carolina, USA
- University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Mattias R Cape
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, USA
- University of Washington, Seattle, Washington, USA
| | - Conner W Lester
- University of North Carolina Wilmington, Wilmington, North Carolina, USA
- Duke University, Durham, North Carolina, USA
| | - Elizabeth Bailey
- University of North Carolina Wilmington, Wilmington, North Carolina, USA
- Yale University, New Haven, Connecticut, USA
| | | | - Robert A York
- University of North Carolina Wilmington, Wilmington, North Carolina, USA
| | - Alyson H Fleming
- University of North Carolina Wilmington, Wilmington, North Carolina, USA
- University of Wisconsin-Madison, Madison, Wisconsin, USA
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2
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Huang Y, Fassbender A, Bushinsky S. Biogenic carbon pool production maintains the Southern Ocean carbon sink. Proc Natl Acad Sci U S A 2023; 120:e2217909120. [PMID: 37099629 PMCID: PMC10160987 DOI: 10.1073/pnas.2217909120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 03/29/2023] [Indexed: 04/28/2023] Open
Abstract
Through biological activity, marine dissolved inorganic carbon (DIC) is transformed into different types of biogenic carbon available for export to the ocean interior, including particulate organic carbon (POC), dissolved organic carbon (DOC), and particulate inorganic carbon (PIC). Each biogenic carbon pool has a different export efficiency that impacts the vertical ocean carbon gradient and drives natural air-sea carbon dioxide gas (CO2) exchange. In the Southern Ocean (SO), which presently accounts for ~40% of the anthropogenic ocean carbon sink, it is unclear how the production of each biogenic carbon pool contributes to the contemporary air-sea CO2 exchange. Based on 107 independent observations of the seasonal cycle from 63 biogeochemical profiling floats, we provide the basin-scale estimate of distinct biogenic carbon pool production. We find significant meridional variability with enhanced POC production in the subantarctic and polar Antarctic sectors and enhanced DOC production in the subtropical and sea-ice-dominated sectors. PIC production peaks between 47°S and 57°S near the "great calcite belt." Relative to an abiotic SO, organic carbon production enhances CO2 uptake by 2.80 ± 0.28 Pg C y-1, while PIC production diminishes CO2 uptake by 0.27 ± 0.21 Pg C y-1. Without organic carbon production, the SO would be a CO2 source to the atmosphere. Our findings emphasize the importance of DOC and PIC production, in addition to the well-recognized role of POC production, in shaping the influence of carbon export on air-sea CO2 exchange.
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Affiliation(s)
- Yibin Huang
- Department of Ocean Sciences, University of California, Santa Cruz, CA95064
- National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory, Seattle, WA98115
| | - Andrea J. Fassbender
- Department of Ocean Sciences, University of California, Santa Cruz, CA95064
- National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory, Seattle, WA98115
| | - Seth M. Bushinsky
- Department of Oceanography, University of Hawaii at Mānoa, Honolulu, HA96822
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3
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Lacour L, Llort J, Briggs N, Strutton PG, Boyd PW. Seasonality of downward carbon export in the Pacific Southern Ocean revealed by multi-year robotic observations. Nat Commun 2023; 14:1278. [PMID: 36890139 PMCID: PMC9995333 DOI: 10.1038/s41467-023-36954-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 02/27/2023] [Indexed: 03/10/2023] Open
Abstract
At high latitudes, the biological carbon pump, which exports organic matter from the surface ocean to the interior, has been attributed to the gravitational sinking of particulate organic carbon. Conspicuous deficits in ocean carbon budgets challenge this as a sole particle export pathway. Recent model estimates revealed that particle injection pumps have a comparable downward flux of particulate organic carbon to the biological gravitational pump, but with different seasonality. To date, logistical constraints have prevented concomitant and extensive observations of these mechanisms. Here, using year-round robotic observations and recent advances in bio-optical signal analysis, we concurrently investigated the functioning of two particle injection pumps, the mixed layer and eddy subduction pumps, and the gravitational pump in Southern Ocean waters. By comparing three annual cycles in contrasting physical and biogeochemical environments, we show how physical forcing, phytoplankton phenology and particle characteristics influence the magnitude and seasonality of these export pathways, with implications for carbon sequestration efficiency over the annual cycle.
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Affiliation(s)
- Léo Lacour
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia. .,Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-Mer, France.
| | - Joan Llort
- Barcelona Supercomputing Center, Earth Sciences Dept., Barcelona, Spain
| | | | - Peter G Strutton
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia.,Australian Research Council Centre of Excellence for Climate Extremes, University of Tasmania, Hobart, Australia
| | - Philip W Boyd
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia
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4
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Ryan-Keogh TJ, Thomalla SJ, Monteiro PMS, Tagliabue A. Multidecadal trend of increasing iron stress in Southern Ocean phytoplankton. Science 2023; 379:834-840. [PMID: 36821685 DOI: 10.1126/science.abl5237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Southern Ocean primary productivity is principally controlled by adjustments in light and iron limitation, but the spatial and temporal determinants of iron availability, accessibility, and demand are poorly constrained, which hinders accurate long-term projections. We present a multidecadal record of phytoplankton photophysiology between 1996 and 2022 from historical in situ datasets collected by Biogeochemical Argo (BGC-Argo) floats and ship-based platforms. We find a significant multidecadal trend in irradiance-normalized nonphotochemical quenching due to increasing iron stress, with concomitant declines in regional net primary production. The observed trend of increasing iron stress results from changing Southern Ocean mixed-layer physics as well as complex biological and chemical feedback that is indicative of important ongoing changes to the Southern Ocean carbon cycle.
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Affiliation(s)
- Thomas J Ryan-Keogh
- Southern Ocean Carbon-Climate Observatory, CSIR, Cape Town 7700, South Africa
| | - Sandy J Thomalla
- Southern Ocean Carbon-Climate Observatory, CSIR, Cape Town 7700, South Africa
- Marine and Antarctic Research for Innovation and Sustainability, University of Cape Town, Cape Town 7700, South Africa
| | - Pedro M S Monteiro
- Southern Ocean Carbon-Climate Observatory, CSIR, Cape Town 7700, South Africa
- School for Climate Studies, Stellenbosch University, Stellenbosch 7602, South Africa
| | - Alessandro Tagliabue
- Department of Earth, Ocean and Ecological Sciences, School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK
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5
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Liu X, Georgakakos AP. Chlorophyll a estimation in lakes using multi-parameter sonde data. WATER RESEARCH 2021; 205:117661. [PMID: 34560618 DOI: 10.1016/j.watres.2021.117661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/30/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
Algae blooms are of considerable concern in freshwater lakes and reservoirs worldwide. In-situ Chlorophyll a (Chl-a) fluorometers are widely used for rapid assessments of algae biomass. However, accurately converting Chl-a fluorescence to an equivalent concentration is challenging due to natural variations in the relationship as well as nonphotochemical quenching (NPQ) which occurs commonly in surface waters during daytime. This study is based on water quality data from a freshwater lake from October 2018 to December 2020. Initial analysis of sonde Chl-a fluorescence and laboratory extracted Chl-a concentrations shows that the two data sets exhibit a nonlinear relationship with positive correlation and significant errors. A bias correction method was next developed based on (1) concurrent sonde measurements of other water quality parameters (to account for nonlinearities) and (2) a bias correction approach for nonphotochemical quenching effects in surface waters. The new Chl-a model exhibits much improved accuracy, with a root mean square error (RMSE) less than 0.95 µg/L. The new method facilitates accurate Chl-a characterization in freshwater lakes and reservoirs based on readily obtainable in-situ fluorescence sonde measurements.
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Affiliation(s)
- Xiaofeng Liu
- Georgia Water Resources Institute, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Aris P Georgakakos
- Georgia Water Resources Institute, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
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6
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Cornec M, Claustre H, Mignot A, Guidi L, Lacour L, Poteau A, D'Ortenzio F, Gentili B, Schmechtig C. Deep Chlorophyll Maxima in the Global Ocean: Occurrences, Drivers and Characteristics. GLOBAL BIOGEOCHEMICAL CYCLES 2021; 35:e2020GB006759. [PMID: 35860208 PMCID: PMC9285500 DOI: 10.1029/2020gb006759] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 03/05/2021] [Accepted: 03/09/2021] [Indexed: 05/28/2023]
Abstract
Stratified oceanic systems are characterized by the presence of a so-called Deep Chlorophyll a Maximum (DCM) not detectable by ocean color satellites. A DCM can either be a phytoplankton (carbon) biomass maximum (Deep Biomass Maximum, DBM), or the consequence of photoacclimation processes (Deep photoAcclimation Maximum, DAM) resulting in the increase of chlorophyll a per phytoplankton carbon. Even though these DCM (further qualified as either DBMs or DAMs) have long been studied, no global-scale assessment has yet been undertaken and large knowledge gaps still remain in relation to the environmental drivers responsible for their formation and maintenance. In order to investigate their spatial and temporal variability in the open ocean, we use a global data set acquired by more than 500 Biogeochemical-Argo floats given that DCMs can be detected from the comparative vertical distribution of chlorophyll a concentrations and particulate backscattering coefficients. Our findings show that the seasonal dynamics of the DCMs are clearly region-dependent. High-latitude environments are characterized by a low occurrence of intense DBMs, restricted to summer. Meanwhile, oligotrophic regions host permanent DAMs, occasionally replaced by DBMs in summer, while subequatorial waters are characterized by permanent DBMs benefiting from favorable conditions in terms of both light and nutrients. Overall, the appearance and depth of DCMs are primarily driven by light attenuation in the upper layer. Our present assessment of DCM occurrence and of environmental conditions prevailing in their development lay the basis for a better understanding and quantification of their role in carbon budgets (primary production and export).
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Affiliation(s)
- M. Cornec
- CNRS & Sorbonne UniversitéLaboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | - H. Claustre
- CNRS & Sorbonne UniversitéLaboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | - A. Mignot
- Mercator Océan InternationalRamonville‐Saint‐AgneFrance
| | - L. Guidi
- CNRS & Sorbonne UniversitéLaboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | - L. Lacour
- Takuvik Joint International LaboratoryLaval University (Canada) ‐ CNRS (France)Département de biologie et Québec‐OcéanUniversité de LavalQuébecQCCanada
| | - A. Poteau
- CNRS & Sorbonne UniversitéLaboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | - F. D'Ortenzio
- CNRS & Sorbonne UniversitéLaboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | - B. Gentili
- CNRS & Sorbonne UniversitéLaboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | - C. Schmechtig
- CNRS & Sorbonne UniversitéLaboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
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7
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Terrats L, Claustre H, Cornec M, Mangin A, Neukermans G. Detection of Coccolithophore Blooms With BioGeoChemical-Argo Floats. GEOPHYSICAL RESEARCH LETTERS 2020; 47:e2020GL090559. [PMID: 33380764 PMCID: PMC7757229 DOI: 10.1029/2020gl090559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 06/12/2023]
Abstract
Coccolithophores (calcifying phytoplankton) form extensive blooms in temperate and subpolar oceans as evidenced from ocean-color satellites. This study examines the potential to detect coccolithophore blooms with BioGeoChemical-Argo (BGC-Argo) floats, autonomous ocean profilers equipped with bio-optical and physicochemical sensors. We first matched float data to ocean-color satellite data of calcite concentration to select floats that sampled coccolithophore blooms. We identified two floats in the Southern Ocean, which measured the particulate beam attenuation coefficient (c p) in addition to two core BGC-Argo variables, Chlorophyll-a concentration ([Chl-a]) and the particle backscattering coefficient (b bp). We show that coccolithophore blooms can be identified from floats by distinctively high values of (1) the b bp/c p ratio, a proxy for the refractive index of suspended particles, and (2) the b bp/[Chl-a] ratio, measurable by any BGC-Argo float. The latter thus paves the way to global investigations of environmental control of coccolithophore blooms and their role in carbon export.
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Affiliation(s)
- L. Terrats
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
- ACRI‐STSophia AntipolisFrance
| | - H. Claustre
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | - M. Cornec
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOVVillefranche‐sur‐MerFrance
| | | | - G. Neukermans
- Biology Department, MarSens Research GroupGhent UniversityGhentBelgium
- Flanders Marine Institute (VLIZ), InnovOcean siteOstendBelgium
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8
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Kostakis I, Röttgers R, Orkney A, Bouman HA, Porter M, Cottier F, Berge J, McKee D. Development of a bio-optical model for the Barents Sea to quantitatively link glider and satellite observations. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190367. [PMID: 32862821 PMCID: PMC7481666 DOI: 10.1098/rsta.2019.0367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A bio-optical model for the Barents Sea is determined from a set of in situ observations of inherent optical properties (IOPs) and associated biogeochemical analyses. The bio-optical model provides a pathway to convert commonly measured parameters from glider-borne sensors (CTD, optical triplet sensor-chlorophyll and CDOM fluorescence, backscattering coefficients) to bulk spectral IOPs (absorption, attenuation and backscattering). IOPs derived from glider observations are subsequently used to estimate remote sensing reflectance spectra that compare well with coincident satellite observations, providing independent validation of the general applicability of the bio-optical model. Various challenges in the generation of a robust bio-optical model involving dealing with partial and limited quantity datasets and the interpretation of data from the optical triplet sensor are discussed. Establishing this quantitative link between glider-borne and satellite-borne data sources is an important step in integrating these data streams and has wide applicability for current and future integrated autonomous observation systems. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
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Affiliation(s)
- I. Kostakis
- Physics Department, University of Strathclyde, Glasgow, UK
- e-mail:
| | - R. Röttgers
- Remote Sensing Department, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
| | - A. Orkney
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - H. A. Bouman
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - M. Porter
- Scottish Association for Marine Science, Oban, UK
| | - F. Cottier
- Scottish Association for Marine Science, Oban, UK
- Department Arctic and Marine biology, Faculty for Bioscience, Fisheries and Economy, UiT The Arctic University of Norway, Tromsø, Norway
| | - J. Berge
- Department Arctic and Marine biology, Faculty for Bioscience, Fisheries and Economy, UiT The Arctic University of Norway, Tromsø, Norway
- Department of Arctic Biology, University Center on Svalbard, Longyearbyen, Norway
- Department of Biology, NTNU AMOS—Center of Autonomous Marine Operations and Systems, Norwegian University of Technology and Science, Trondheim, Norway
| | - D. McKee
- Physics Department, University of Strathclyde, Glasgow, UK
- Department Arctic and Marine biology, Faculty for Bioscience, Fisheries and Economy, UiT The Arctic University of Norway, Tromsø, Norway
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9
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Scofield AE, Watkins JM, Osantowski E, Rudstam LG. Deep chlorophyll maxima across a trophic state gradient: A case study in the Laurentian Great Lakes. LIMNOLOGY AND OCEANOGRAPHY 2020; 65:2460-2484. [PMID: 33288967 PMCID: PMC7687176 DOI: 10.1002/lno.11464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 01/06/2020] [Accepted: 02/15/2020] [Indexed: 05/19/2023]
Abstract
Deep chlorophyll maxima (DCM) are common in stratified lakes and oceans, and phytoplankton growth within DCM often contributes significantly to total system production. Theory suggests that properties of DCM should be predictable by trophic state, with DCM becoming deeper, broader, and less productive with greater oligotrophy. However, rigorous tests of these expectations are lacking in freshwater systems. We use data generated by the U.S. EPA from 1996 to 2017, including in situ profile data for temperature, photosynthetically active radiation (PAR), chlorophyll, beam attenuation (c p), and dissolved oxygen (DO), to investigate patterns in DCM across lakes and over time. We consider trophic state, 1% PAR depth (z 1%), thermal structure, and degree of photoacclimation as potential drivers of DCM characteristics. DCM depth and thickness generally increased while DCM chlorophyll concentration decreased with decreasing trophic state index (greater oligotrophy). The z 1% was a stronger predictor of DCM depth than thermal structure. DCM in meso-oligotrophic waters were closely aligned with maxima in c p and DO saturation, suggesting they are autotrophically productive. However, the depths of these maxima diverged in ultra-oligotrophic waters, with DCM occurring deepest. This is likely a consequence of photoacclimation in high-transparency waters, where c p can be a better proxy for phytoplankton biomass than chlorophyll. Our results are generally consistent with expectations from DCM theory, but they also identify specific gaps in our understanding of DCM in lakes, including the causes of multiple DCM, the importance of nutriclines, and the processes forming DCM at higher light levels than expected.
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Affiliation(s)
- Anne E. Scofield
- Cornell UniversityIthacaNew York
- Purdue UniversityWest LafayetteIndiana
| | | | - Eric Osantowski
- United States Environmental Protection AgencyGreat Lakes National Program OfficeChicagoIllinois
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10
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Randelhoff A, Lacour L, Marec C, Leymarie E, Lagunas J, Xing X, Darnis G, Penkerc'h C, Sampei M, Fortier L, D'Ortenzio F, Claustre H, Babin M. Arctic mid-winter phytoplankton growth revealed by autonomous profilers. SCIENCE ADVANCES 2020; 6:6/39/eabc2678. [PMID: 32978152 PMCID: PMC7518875 DOI: 10.1126/sciadv.abc2678] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
It is widely believed that during winter and spring, Arctic marine phytoplankton cannot grow until sea ice and snow cover start melting and transmit sufficient irradiance, but there is little observational evidence for that paradigm. To explore the life of phytoplankton during and after the polar night, we used robotic ice-avoiding profiling floats to measure ocean optics and phytoplankton characteristics continuously through two annual cycles in Baffin Bay, an Arctic sea that is covered by ice for 7 months a year. We demonstrate that net phytoplankton growth occurred even under 100% ice cover as early as February and that it resulted at least partly from photosynthesis. This highlights the adaptation of Arctic phytoplankton to extreme low-light conditions, which may be key to their survival before seeding the spring bloom.
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Affiliation(s)
- Achim Randelhoff
- Takuvik Joint International Laboratory, Université Laval (QC, Canada) and CNRS (France).
- Département de biologie, Université Laval and Québec-Océan, QC, Canada
| | - Léo Lacour
- Takuvik Joint International Laboratory, Université Laval (QC, Canada) and CNRS (France)
- Département de biologie, Université Laval and Québec-Océan, QC, Canada
| | - Claudie Marec
- Takuvik Joint International Laboratory, Université Laval (QC, Canada) and CNRS (France)
- Institut Universitaire Européen de la Mer, 29280 Plouzané, France
| | - Edouard Leymarie
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (LOV), 06230 Villefranche-sur-Mer, France
| | - José Lagunas
- Takuvik Joint International Laboratory, Université Laval (QC, Canada) and CNRS (France)
- Département de biologie, Université Laval and Québec-Océan, QC, Canada
| | - Xiaogang Xing
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Gérald Darnis
- Takuvik Joint International Laboratory, Université Laval (QC, Canada) and CNRS (France)
- Département de biologie, Université Laval and Québec-Océan, QC, Canada
| | - Christophe Penkerc'h
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (LOV), 06230 Villefranche-sur-Mer, France
| | - Makoto Sampei
- Faculty of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
| | - Louis Fortier
- Takuvik Joint International Laboratory, Université Laval (QC, Canada) and CNRS (France)
- Département de biologie, Université Laval and Québec-Océan, QC, Canada
| | - Fabrizio D'Ortenzio
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (LOV), 06230 Villefranche-sur-Mer, France
| | - Hervé Claustre
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (LOV), 06230 Villefranche-sur-Mer, France
| | - Marcel Babin
- Takuvik Joint International Laboratory, Université Laval (QC, Canada) and CNRS (France)
- Département de biologie, Université Laval and Québec-Océan, QC, Canada
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11
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Evaluation of Ocean Color Remote Sensing Algorithms for Diffuse Attenuation Coefficients and Optical Depths with Data Collected on BGC-Argo Floats. REMOTE SENSING 2020. [DOI: 10.3390/rs12152367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The vertical distribution of irradiance in the ocean is a key input to quantify processes spanning from radiative warming, photosynthesis to photo-oxidation. Here we use a novel dataset of thousands local-noon downwelling irradiance at 490 nm (Ed(490)) and photosynthetically available radiation (PAR) profiles captured by 103 BGC-Argo floats spanning three years (from October 2012 to January 2016) in the world’s ocean, to evaluate several published algorithms and satellite products related to diffuse attenuation coefficient (Kd). Our results show: (1) MODIS-Aqua Kd(490) products derived from a blue-to-green algorithm and two semi-analytical algorithms show good consistency with the float-observed values, but the Chla-based one has overestimation in oligotrophic waters; (2) The Kd(PAR) model based on the Inherent Optical Properties (IOPs) performs well not only at sea-surface but also at depth, except for the oligotrophic waters where Kd(PAR) is underestimated below two penetration depth (2zpd), due to the model’s assumption of a homogeneous distribution of IOPs in the water column which is not true in most oligotrophic waters with deep chlorophyll-a maxima; (3) In addition, published algorithms for the 1% euphotic-layer depth and the depth of 0.415 mol photons m−2 d−1 isolume are evaluated. Algorithms based on Chla generally work well while IOPs-based ones exhibit an overestimation issue in stratified and oligotrophic waters, due to the underestimation of Kd(PAR) at depth.
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12
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Claustre H, Johnson KS, Takeshita Y. Observing the Global Ocean with Biogeochemical-Argo. ANNUAL REVIEW OF MARINE SCIENCE 2020; 12:23-48. [PMID: 31433959 DOI: 10.1146/annurev-marine-010419-010956] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Biogeochemical-Argo (BGC-Argo) is a network of profiling floats carrying sensors that enable observation of as many as six essential biogeochemical and bio-optical variables: oxygen, nitrate, pH, chlorophyll a, suspended particles, and downwelling irradiance. This sensor network represents today's most promising strategy for collecting temporally and vertically resolved observations of biogeochemical properties throughout the ocean. All data are freely available within 24 hours of transmission. These data fill large gaps in ocean-observing systems and support three ambitions: gaining a better understanding of biogeochemical processes (e.g., the biological carbon pump and air-sea CO2 exchanges) and evaluating ongoing changes resulting from increasing anthropogenic pressure (e.g., acidification and deoxygenation); managing the ocean (e.g., improving the global carbon budget and developing sustainable fisheries); and carrying out exploration for potential discoveries. The BGC-Argo network has already delivered extensive high-quality global data sets that have resulted in unique scientific outcomes from regional to global scales. With the proposed expansion of BGC-Argo in the near future, this network has the potential to become a pivotal observation system that links satellite and ship-based observations in a transformative manner.
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Affiliation(s)
- Hervé Claustre
- Laboratoire d'Océanographie de Villefranche, Institut de la Mer de Villefranche, CNRS, Sorbonne Université, 06230 Villefranche-sur-Mer, France;
| | - Kenneth S Johnson
- Monterey Bay Aquarium Research Institute, Moss Landing, California 95039, USA; ,
| | - Yuichiro Takeshita
- Monterey Bay Aquarium Research Institute, Moss Landing, California 95039, USA; ,
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Gittings JA, Raitsos DE, Kheireddine M, Racault MF, Claustre H, Hoteit I. Evaluating tropical phytoplankton phenology metrics using contemporary tools. Sci Rep 2019; 9:674. [PMID: 30679755 PMCID: PMC6345824 DOI: 10.1038/s41598-018-37370-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 12/04/2018] [Indexed: 11/24/2022] Open
Abstract
The timing of phytoplankton growth (phenology) in tropical oceans is a crucial factor influencing the survival rates of higher trophic levels, food web structure and the functioning of coral reef ecosystems. Phytoplankton phenology is thus categorised as an 'ecosystem indicator', which can be utilised to assess ecosystem health in response to environmental and climatic perturbations. Ocean-colour remote sensing is currently the only technique providing global, long-term, synoptic estimates of phenology. However, due to limited available in situ datasets, studies dedicated to the validation of satellite-derived phenology metrics are sparse. The recent development of autonomous oceanographic observation platforms provides an opportunity to bridge this gap. Here, we use satellite-derived surface chlorophyll-a (Chl-a) observations, in conjunction with a Biogeochemical-Argo dataset, to assess the capability of remote sensing to estimate phytoplankton phenology metrics in the northern Red Sea - a typical tropical marine ecosystem. We find that phenology metrics derived from both contemporary platforms match with a high degree of precision (within the same 5-day period). The remotely-sensed surface signatures reflect the overall water column dynamics and successfully capture Chl-a variability related to convective mixing. Our findings offer important insights into the capability of remote sensing for monitoring food availability in tropical marine ecosystems, and support the use of satellite-derived phenology as an ecosystem indicator for marine management strategies in regions with limited data availability.
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Affiliation(s)
- John A Gittings
- Department of Earth Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Dionysios E Raitsos
- Remote Sensing Group, Plymouth Marine Laboratory (PML), The Hoe, Plymouth, PL1 3DH, United Kingdom
- National Centre for Earth Observation (NCEO), Plymouth Marine Laboratory (PML), The Hoe, Plymouth, PL1 3DH, United Kingdom
- Department of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Malika Kheireddine
- Red Sea Research Centre, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Marie-Fanny Racault
- Remote Sensing Group, Plymouth Marine Laboratory (PML), The Hoe, Plymouth, PL1 3DH, United Kingdom
- National Centre for Earth Observation (NCEO), Plymouth Marine Laboratory (PML), The Hoe, Plymouth, PL1 3DH, United Kingdom
| | - Hervé Claustre
- Marine Optics and Remote Sensing Laboratory, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-Mer, France
| | - Ibrahim Hoteit
- Department of Earth Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
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