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Dansie AP, Thomas DSG, Wiggs GFS, Baddock MC, Ashpole I. Plumes and blooms - Locally-sourced Fe-rich aeolian mineral dust drives phytoplankton growth off southwest Africa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 829:154562. [PMID: 35306076 DOI: 10.1016/j.scitotenv.2022.154562] [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: 11/08/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Ocean-based photosynthesis accounts for half of global primary production. Productivity rates, driven by phytoplanktonic responses to nutrient availability, are however highly variable both spatially and temporally throughout the oceans. Intense primary production in the ocean's most productive areas, the Eastern Boundary Upwelling Systems (EBUS), cannot be fully explained by nutrient upwelling alone, with the role of local dust sources and complimentary aeolian nutrient delivery largely overlooked. Here we explore relationships between iron-rich dust plumes emanating from a significant regional dust source, Namibia's ephemeral river valleys, and blooms of phytoplankton growth off southwest Africa in the Benguela Upwelling System (BUS). We constrain dust source dynamics through field measurement of in-valley airborne dust concentrations made at daily resolution, and couple these with satellite observations of atmospheric aerosols, ocean phytoplankton concentrations, and sea surface temperature over a six-month period encompassing the known 'dust season' of the valley sources. Phytoplanktonic responses in BUS waters to individual dust emission events were identified and were importantly shown to be unassociated with upwelling events. We demonstrate a fast (1-2 day) chlorophyllic response to observed iron-rich dust emissions, a relationship that is concealed by monthly averaged data. We show that terrestrial in-valley airborne dust concentrations correlate with offshore increases in phytoplankton concentrations, providing the first study of oceanic response that is directly linked with a specific monitored terrestrial dust source.
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Affiliation(s)
- A P Dansie
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Sydney, NSW 2052, Australia; School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK.
| | - D S G Thomas
- School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK; Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa
| | - G F S Wiggs
- School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK
| | - M C Baddock
- Geography and Environment, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
| | - I Ashpole
- Department of Environmental Science, Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada
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Anomalous wind triggered the largest phytoplankton bloom in the oligotrophic North Pacific Subtropical Gyre. Sci Rep 2019; 9:15550. [PMID: 31664110 PMCID: PMC6820777 DOI: 10.1038/s41598-019-51989-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 10/09/2019] [Indexed: 12/01/2022] Open
Abstract
In summer 2010, a massive bloom appeared in the middle (16–25°N, 160–200°E) of the North Pacific Subtropical Gyre (NPSG) creating a spectacular oasis in the middle of the largest oceanic desert on Earth. Peaked in June 2010 covering over two million km2 in space, this phytoplankton bloom is the largest ever recorded by ocean color satellites in the NPSG over the period from 1997 to 2013. The initiation and mechanisms sustaining the massive bloom were due to atmospheric and oceanic anomalies. Over the north (25–30°N) of the bloom, strong anticyclonic winds warmed sea surface temperature (SST) via Ekman convergence. Subsequently, anomalous westward ocean currents were generated by SST meridional gradients between 19°N and 25°N, producing strong velocity shear that caused large number of mesoscale (100-km in order) cyclonic eddies in the bloom region. The ratio of cyclonic to anticyclonic eddies of 2.7 in summer 2010 is the highest over the 16-year study period. As a result of the large eddy-number differences, eddy-eddy interactions were strong and induced submesoscale (smaller than 100 km) vertical pumping as observed in the in-situ ocean profiles. The signature of vertical pumping was also presented in the in-situ measurements of chlorophyll and nutrients, which show higher concentrations in 2010 than other years.
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Bali K, Mishra AK, Singh S, Chandra S, Lehahn Y. Impact of dust storm on phytoplankton bloom over the Arabian Sea: a case study during March 2012. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:11940-11950. [PMID: 30825122 DOI: 10.1007/s11356-019-04602-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 02/18/2019] [Indexed: 06/09/2023]
Abstract
Dust storms affect the primary productivity of the ocean by providing necessary micronutrients to the surface layer. One such dust storm during March 2012 led to a substantial reduction in visibility and enhancement in aerosol optical depth (AOD) up to ~ 0.8 (AOD increased from 0.1 to 0.9) over the Arabian Sea. We explored the possible effects and mechanisms through which this particular dust storm could impact the ocean's primary productivity (phytoplankton concentration), using satellite-borne remote sensors and reanalysis model data (2003-2016). The climatological analyses revealed anomalous March 2012 in terms of dust deposition and enhancement in phytoplankton concentration in the month of March during 2003-2016 over this region. The studied dust storm accounts for increase in the daily average surface dust deposition rate from ~ 3 to ~53 mg m-2 day-1, which is followed by a significant enhancement in the chlorophyll-a (Chl_a) concentration (~ 2 to ~9 mg m-3). We show strong association between a dust storm and an event of anomalously high biological production (with a 4-day forward lag) in the Arabian Sea. We suggest that the increase in biological production results from the superposition of two complementary processes (deposition of atmospheric nutrients and deepening of the mixed layer due to dust-induced sea surface temperature cooling) that enhance nutrient availability in the euphotic layer.
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Affiliation(s)
- Kunal Bali
- Environmental Sciences and Biomedical Metrology Division, CSIR-National Physical Laboratory, New Delhi, 110012, India
- Centre for Atmospheric Sciences, Indian Institute of Technology, New Delhi, 110016, India
| | - Amit Kumar Mishra
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Sachchidanand Singh
- Environmental Sciences and Biomedical Metrology Division, CSIR-National Physical Laboratory, New Delhi, 110012, India.
- CSIR-National Physical Laboratory Campus, Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110012, India.
| | - Subhash Chandra
- Environmental Sciences and Biomedical Metrology Division, CSIR-National Physical Laboratory, New Delhi, 110012, India
| | - Yoav Lehahn
- Department of Marine Geosciences, University of Haifa, 3498838, Haifa, Israel
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Anderson EE, Wilson C, Knap AH, Villareal TA. Summer diatom blooms in the eastern North Pacific gyre investigated with a long-endurance autonomous surface vehicle. PeerJ 2018; 6:e5387. [PMID: 30128189 PMCID: PMC6098680 DOI: 10.7717/peerj.5387] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/17/2018] [Indexed: 11/20/2022] Open
Abstract
Satellite chlorophyll a (chl a) observations have repeatedly noted summertime phytoplankton blooms in the North Pacific subtropical gyre (NPSG), a region of open ocean that is far removed from any land-derived or Ekman upwelling nutrient sources. These blooms are dominated by N2-fixing diatom-cyanobacteria associations of the diatom genera Rhizosolenia Brightwell and Hemiaulus Ehrenberg. Their nitrogen fixing endosymbiont, Richelia intracellularis J.A. Schmidt, is hypothesized to be critical to the development of blooms in this nitrogen limited region. However, due to the remote location and unpredictable duration of the summer blooms, prolonged in situ observations are rare outside of the Station ALOHA time-series off of Hawai'i. In summer, 2015, a proof-of-concept mission using the autonomous vehicle, Honey Badger (Wave Glider SV2; Liquid Robotics, a Boeing company, Sunnyvale, CA, USA), collected near-surface (<20 m) observations in the NPSG using hydrographic, meteorological, optical, and imaging sensors designed to focus on phytoplankton abundance, distribution, and physiology of this bloom-forming region. Hemiaulus and Rhizosolenia cell abundance was determined using digital holography for the entire June-November mission. Honey Badger was not able to reach the 30°N subtropical front region where most of the satellite chl a blooms have been observed, but near-real time navigational control allowed it to transect two blooms near 25°N. The two taxa did not co-occur in large numbers, rather the blooms were dominated by either Hemiaulus or Rhizosolenia. The August 2-4, 2015 bloom was comprised of 96% Hemiaulus and the second bloom, August 15-17, 2015, was dominated by Rhizosolenia (75%). The holograms also imaged undisturbed, fragile Hemiaulus aggregates throughout the sampled area at ∼10 L-1. Aggregated Hemiaulus represented the entire observed population at times and had a widespread distribution independent of the summer export pulse, a dominant annual event suggested to be mediated by aggregate fluxes. Aggregate occurrence was not consistent with a density dependent formation mechanism and may represent a natural growth form in undisturbed conditions. The photosynthetic potential index (Fv:Fm) increased from ∼0.4 to ∼0.6 during both blooms indicating a robust, active phytoplankton community in the blooms. The diel pattern of Fv:Fm (nocturnal maximum; diurnal minimum) was consistent with macronutrient limitation throughout the mission with no evidence of Fe-limitation despite the presence of nitrogen fixing diatom-diazotroph assemblages. During the 5-month mission, Honey Badger covered ∼5,690 km (3,070 nautical miles), acquired 9,336 holograms, and reliably transmitted data onshore in near real-time. Software issues developed with the active fluorescence sensor that terminated measurements in early September. Although images were still useful at the end of the mission, fouling of the LISST-Holo optics was considerable, and appeared to be the most significant issue facing deployments of this duration.
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Affiliation(s)
- Emily E. Anderson
- Department of Marine Science and Marine Science Institute, The University of Texas at Austin, Port Aransas, TX, USA
| | - Cara Wilson
- National Marine Fisheries, National Oceanic and Atmospheric Administration, Monterey, CA, USA
| | - Anthony H. Knap
- Geochemical and Environmental Research Group, Texas A&M University, College Station, TX, USA
| | - Tracy A. Villareal
- Department of Marine Science and Marine Science Institute, The University of Texas at Austin, Port Aransas, TX, USA
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Lehahn Y, d'Ovidio F, Koren I. A Satellite-Based Lagrangian View on Phytoplankton Dynamics. ANNUAL REVIEW OF MARINE SCIENCE 2018; 10:99-119. [PMID: 28961072 DOI: 10.1146/annurev-marine-121916-063204] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The well-lit upper layer of the open ocean is a dynamical environment that hosts approximately half of global primary production. In the remote parts of this environment, distant from the coast and from the seabed, there is no obvious spatially fixed reference frame for describing the dynamics of the microscopic drifting organisms responsible for this immense production of organic matter-the phytoplankton. Thus, a natural perspective for studying phytoplankton dynamics is to follow the trajectories of water parcels in which the organisms are embedded. With the advent of satellite oceanography, this Lagrangian perspective has provided valuable information on different aspects of phytoplankton dynamics, including bloom initiation and termination, spatial distribution patterns, biodiversity, export of carbon to the deep ocean, and, more recently, bottom-up mechanisms that affect the distribution and behavior of higher-trophic-level organisms. Upcoming submesoscale-resolving satellite observations and swarms of autonomous platforms open the way to the integration of vertical dynamics into the Lagrangian view of phytoplankton dynamics.
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Affiliation(s)
- Yoav Lehahn
- Department of Marine Geosciences, University of Haifa, Haifa 3498838, Israel;
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel;
| | - Francesco d'Ovidio
- Sorbonne Université (UPMC Paris 6/CNRS/IRD/MNHN), LOCEAN-IPSL, 75005 Paris, France;
| | - Ilan Koren
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel;
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Satellite-Observed Transport of Dust to the East China Sea and the North Pacific Subtropical Gyre: Contribution of Dust to the Increase in Chlorophyll during Spring 2010. ATMOSPHERE 2016. [DOI: 10.3390/atmos7110152] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Niu H, Zhang D, Hu W, Shi J, Li R, Gao H, Pian W, Hu M. Size and elemental composition of dry-deposited particles during a severe dust storm at a coastal site of Eastern China. J Environ Sci (China) 2016; 40:161-168. [PMID: 26969556 DOI: 10.1016/j.jes.2015.09.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 08/27/2015] [Accepted: 09/14/2015] [Indexed: 06/05/2023]
Abstract
Dry-deposited particles were collected during the passage of an extremely strong dust storm in March, 2010 at a coastal site in Qingdao (36.15 °N, 120.49 °E), a city located in Eastern China. The size, morphology, and elemental composition of the particles were quantified with a scanning electron microscope equipped with an energy dispersive X-ray instrument (SEM-EDX). The particles appeared in various shapes, and their size mainly varied from 0.4 to 10 μm, with the mean diameters of 0.5, 1.5, and 1.0 μm before, during, and after the dust storm, respectively. The critical size of the mineral particles settling on the surface in the current case was about 0.3-0.4 μm before the dust storm and about 0.5-0.7 μm during the dust storm. Particles that appeared in high concentration but were smaller than the critical size deposited onto the surface at a small number flux. The elements Al, Si and Mg were frequently detected in all samples, indicating the dominance of mineral particles. The frequency of Al in particles collected before the dust storm was significantly lower than for those collected during and after the dust storm. The frequencies of Cl and Fe did not show obvious changes, while those of S, K and Ca decreased after the dust arrival. These results indicate that the dust particles deposited onto the surface were less influenced by anthropogenic pollutants in terms of particle number.
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Affiliation(s)
- Hongya Niu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Hebei Collaborative Innovation Center of Coal Exploitation, Hebei University of Engineering, Handan 056038, Hebei, China
| | - Daizhou Zhang
- Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
| | - Wei Hu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
| | - Jinhui Shi
- Key Laboratory of Marine Environmental Science and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Ruipeng Li
- Key Laboratory of Marine Environmental Science and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Huiwang Gao
- Key Laboratory of Marine Environmental Science and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Wei Pian
- Hebei Collaborative Innovation Center of Coal Exploitation, Hebei University of Engineering, Handan 056038, Hebei, China
| | - Min Hu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
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White AE, Letelier RM, Whitmire AL, Barone B, Bidigare RR, Church MJ, Karl DM. Phenology of particle size distributions and primary productivity in the North Pacific subtropical gyre (Station ALOHA). JOURNAL OF GEOPHYSICAL RESEARCH. OCEANS 2015; 120:7381-7399. [PMID: 27812434 PMCID: PMC5068454 DOI: 10.1002/2015jc010897] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 08/31/2015] [Indexed: 06/06/2023]
Abstract
The particle size distribution (PSD) is a critical aspect of the oceanic ecosystem. Local variability in the PSD can be indicative of shifts in microbial community structure and reveal patterns in cell growth and loss. The PSD also plays a central role in particle export by influencing settling speed. Satellite-based models of primary productivity (PP) often rely on aspects of photophysiology that are directly related to community size structure. In an effort to better understand how variability in particle size relates to PP in an oligotrophic ecosystem, we collected laser diffraction-based depth profiles of the PSD and pigment-based classifications of phytoplankton functional types (PFTs) on an approximately monthly basis at the Hawaii Ocean Time-series Station ALOHA, in the North Pacific subtropical gyre. We found a relatively stable PSD in the upper water column. However, clear seasonality is apparent in the vertical distribution of distinct particle size classes. Neither laser diffraction-based estimations of relative particle size nor pigment-based PFTs was found to be significantly related to the rate of 14C-based PP in the light-saturated upper euphotic zone. This finding indicates that satellite retrievals of particle size, based on particle scattering or ocean color would not improve parameterizations of present-day bio-optical PP models for this region. However, at depths of 100-125 m where irradiance exerts strong control on PP, we do observe a significant linear relationship between PP and the estimated carbon content of 2-20 μm particles.
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Affiliation(s)
- Angelicque E White
- College of Earth, Ocean and Atmospheric Sciences Oregon State University Corvallis Oregon USA
| | - Ricardo M Letelier
- College of Earth, Ocean and Atmospheric Sciences Oregon State University Corvallis Oregon USA
| | - Amanda L Whitmire
- Center for Digital Scholarship and Services, Oregon State University Corvallis Oregon USA
| | - Benedetto Barone
- Department of Oceanography University of Hawaii Honolulu Hawaii USA
| | | | - Matthew J Church
- Department of Oceanography University of Hawaii Honolulu Hawaii USA
| | - David M Karl
- Department of Oceanography University of Hawaii Honolulu Hawaii USA
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Luo YW, Ducklow HW, Friedrichs MAM, Church MJ, Karl DM, Doney SC. Interannual variability of primary production and dissolved organic nitrogen storage in the North Pacific Subtropical Gyre. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jg001830] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Guidi L, Calil PHR, Duhamel S, Björkman KM, Doney SC, Jackson GA, Li B, Church MJ, Tozzi S, Kolber ZS, Richards KJ, Fong AA, Letelier RM, Gorsky G, Stemmann L, Karl DM. Does eddy-eddy interaction control surface phytoplankton distribution and carbon export in the North Pacific Subtropical Gyre? ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012jg001984] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Oligotrophic subtropical gyres are the largest oceanic ecosystems, covering >40% of the Earth's surface. Unicellular cyanobacteria and the smallest algae (plastidic protists) dominate CO(2) fixation in these ecosystems, competing for dissolved inorganic nutrients. Here we present direct evidence from the surface mixed layer of the subtropical gyres and adjacent equatorial and temperate regions of the Atlantic Ocean, collected on three Atlantic Meridional Transect cruises on consecutive years, that bacterioplankton are fed on by plastidic and aplastidic protists at comparable rates. Rates of bacterivory were similar in the light and dark. Furthermore, because of their higher abundance, it is the plastidic protists, rather than the aplastidic forms, that control bacterivory in these waters. These findings change our basic understanding of food web function in the open ocean, because plastidic protists should now be considered as the main bacterivores as well as the main CO(2) fixers in the oligotrophic gyres.
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