Articles | Volume 15, issue 13
https://doi.org/10.5194/bg-15-4033-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-15-4033-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
03 Jul 2018
Research article |
| 03 Jul 2018
| 03 Jul 2018
Contributions of the direct supply of belowground seagrass detritus and trapping of suspended organic matter to the sedimentary organic carbon stock in seagrass meadows
Coastal and Estuarine Environment Research Group, Port and Airport
Research Institute, 3-1-1 Nagase, Yokosuka 239-0826, Japan
Kenta Watanabe
Coastal and Estuarine Environment Research Group, Port and Airport
Research Institute, 3-1-1 Nagase, Yokosuka 239-0826, Japan
Shoji Yamamoto
Department of Earth and Planetary Science, the University of Tokyo,
Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
Chuki Hongo
Department of Chemistry, Biology, and Marine Science, University of
the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan
Hajime Kayanne
Department of Earth and Planetary Science, the University of Tokyo,
Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
Tomohiro Kuwae
Coastal and Estuarine Environment Research Group, Port and Airport
Research Institute, 3-1-1 Nagase, Yokosuka 239-0826, Japan
Related authors
No articles found.
Christian Lønborg, Cátia Carreira, Gwenaël Abril, Susana Agustí, Valentina Amaral, Agneta Andersson, Javier Arístegui, Punyasloke Bhadury, Mariana B. Bif, Alberto V. Borges, Steven Bouillon, Maria Ll. Calleja, Luiz C. Cotovicz Jr., Stefano Cozzi, Maryló Doval, Carlos M. Duarte, Bradley Eyre, Cédric G. Fichot, E. Elena García-Martín, Alexandra Garzon-Garcia, Michele Giani, Rafael Gonçalves-Araujo, Renee Gruber, Dennis A. Hansell, Fuminori Hashihama, Ding He, Johnna M. Holding, William R. Hunter, J. Severino P. Ibánhez, Valeria Ibello, Shan Jiang, Guebuem Kim, Katja Klun, Piotr Kowalczuk, Atsushi Kubo, Choon-Weng Lee, Cláudia B. Lopes, Federica Maggioni, Paolo Magni, Celia Marrase, Patrick Martin, S. Leigh McCallister, Roisin McCallum, Patricia M. Medeiros, Xosé Anxelu G. Morán, Frank E. Muller-Karger, Allison Myers-Pigg, Marit Norli, Joanne M. Oakes, Helena Osterholz, Hyekyung Park, Maria Lund Paulsen, Judith A. Rosentreter, Jeff D. Ross, Digna Rueda-Roa, Chiara Santinelli, Yuan Shen, Eva Teira, Tinkara Tinta, Guenther Uher, Masahide Wakita, Nicholas Ward, Kenta Watanabe, Yu Xin, Youhei Yamashita, Liyang Yang, Jacob Yeo, Huamao Yuan, Qiang Zheng, and Xosé Antón Álvarez-Salgado
Earth Syst. Sci. Data, 16, 1107–1119, https://doi.org/10.5194/essd-16-1107-2024, https://doi.org/10.5194/essd-16-1107-2024, 2024
Short summary
Short summary
In this paper, we present the first edition of a global database compiling previously published and unpublished measurements of dissolved organic matter (DOM) collected in coastal waters (CoastDOM v1). Overall, the CoastDOM v1 dataset will be useful to identify global spatial and temporal patterns and to facilitate reuse in studies aimed at better characterizing local biogeochemical processes and identifying a baseline for modelling future changes in coastal waters.
Kenta Watanabe, Goro Yoshida, Masakazu Hori, Yu Umezawa, Hirotada Moki, and Tomohiro Kuwae
Biogeosciences, 17, 2425–2440, https://doi.org/10.5194/bg-17-2425-2020, https://doi.org/10.5194/bg-17-2425-2020, 2020
Short summary
Short summary
Macroalgal beds are among the vegetated coastal ecosystems that take up atmospheric CO2. We investigated the relationships between macroalgal metabolism and inorganic and organic carbon fluxes in a temperate macroalgal bed during the productive time of year. The macroalgal metabolism formed water with low CO2 and high dissolved organic carbon concentrations that was then exported offshore. This export process potentially enhances CO2 uptake in and around macroalgal beds.
Anirban Akhand, Abhra Chanda, Kenta Watanabe, Sourav Das, Tatsuki Tokoro, Kunal Chakraborty, Sugata Hazra, and Tomohiro Kuwae
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-388, https://doi.org/10.5194/bg-2019-388, 2019
Preprint withdrawn
Short summary
Short summary
Globally, mangrove surrounding waters are considered net sources of atmospheric CO2. We estimated the air–water CO2 flux with high temporal resolution in mangrove surrounding waters in the Indian Sundarbans and found that the water can act as a sink or weak source of CO2. We suggest that the CO2 efflux from the mangroves surrounding waters of Sundarbans are much lower than the recently estimated world average, and that such low-efflux areas should be included in global mangrove carbon budgeting.
Chuki Hongo, Haruko Kurihara, and Yimnang Golbuu
Nat. Hazards Earth Syst. Sci., 18, 669–686, https://doi.org/10.5194/nhess-18-669-2018, https://doi.org/10.5194/nhess-18-669-2018, 2018
Short summary
Short summary
Tropical cyclones and sea level rise cause major problems including damage to infrastructure in coastal areas. A green infrastructure for coastal protection will be needed by small island nations. A maintaining reef growth in the future is effective in reducing the risk of coastal damage arising from wave action. The use of coral reefs for disaster risk reduction is a cost-effective approach and includes other benefits derived from the various ecological services provided by living reefs.
Tatsuki Tokoro and Tomohiro Kuwae
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-499, https://doi.org/10.5194/bg-2017-499, 2017
Manuscript not accepted for further review
Short summary
Short summary
The eddy covariance (EC) method is the most promising approach for the measurement of atmospheric CO2 flux. However, the methods are currently in the development stage, and have large uncertainties. In this study, we improved the post-processing procedure for the EC method to reduce the uncertainty. The new processing method is expected to be useful in studies related to ecosystem-atmospheric CO2 interactions.
K. Nakayama, Y. Maruya, K. Matsumoto, M. Komata, K. Komai, and T. Kuwae
Biogeosciences Discuss., https://doi.org/10.5194/bgd-12-18185-2015, https://doi.org/10.5194/bgd-12-18185-2015, 2015
Revised manuscript not accepted
Short summary
Short summary
We conducted field experiments to understand the recycling of total nitrogen from the ocean across an entire river basin using stable isotope analysis. To our best knowledge, for the world's first we estimated the marine derived nutrients recycling rate. This study also demonstrates that TN may be recycled from the ocean to the river basin not only directly due to runs of salmon, but also indirectly due to subsequent transportation processes, such as sea eagles feeding and defecation.
K. Watanabe and T. Kuwae
Biogeosciences, 12, 6251–6258, https://doi.org/10.5194/bg-12-6251-2015, https://doi.org/10.5194/bg-12-6251-2015, 2015
Short summary
Short summary
Our empirical study demonstrates the quantitative evidence of assimilating atmospheric modern CO2 by the seagrass Zostera marina, by analyzing the radiocarbon isotope concentrations (Δ14C) of both the seagrass and two carbon sources in a brackish lagoon. CO2 exchange between the air and water would occur at the very thin film of water over the air-exposed seagrass leaves. Our finding offers better understanding of the role of seagrass meadows in global coastal carbon dynamics.
K. Nakayama, Y. Maruya, K. Matsumoto, M. Komata, K. Komai, and T. Kuwae
Biogeosciences Discuss., https://doi.org/10.5194/bgd-12-5535-2015, https://doi.org/10.5194/bgd-12-5535-2015, 2015
Revised manuscript not accepted
Short summary
Short summary
Recycling of total nitrogen (TN) from the ocean to river basin ecosystems has been actively investigated. Previous studies demonstrated that marine-derived nutrients (MDN) play a large role in river ecosystems. However, little research has been devoted to understanding the contribution of runs of salmon to MDN across the entire river basin. Therefore we conducted field experiments to understand the recycling of TN from the ocean across an entire river basin using stable isotope analysis.
Related subject area
Biogeochemistry: Coastal Ocean
The influence of zooplankton and oxygen on the particulate organic carbon flux in the Benguela Upwelling System
Reviews and syntheses: Biological indicators of low-oxygen stress in marine water-breathing animals
Temperature-enhanced effects of iron on Southern Ocean phytoplankton
Riverine nutrient impact on global ocean nitrogen cycle feedbacks and marine primary production in an Earth system model
The Northeast Greenland Shelf as a potential late-summer CO2 source to the atmosphere
Technical note: Ocean Alkalinity Enhancement Pelagic Impact Intercomparison Project (OAEPIIP)
Estimates of carbon sequestration potential in an expanding Arctic fjord (Hornsund, Svalbard) affected by dark plumes of glacial meltwater
An assessment of ocean alkalinity enhancement using aqueous hydroxides: kinetics, efficiency, and precipitation thresholds
High metabolic zinc demand within native Amundsen and Ross Sea phytoplankton communities determined by stable isotope uptake rate measurements
Dissolved nitric oxide in the lower Elbe Estuary and the Port of Hamburg area
Variable contribution of wastewater treatment plant effluents to downstream nitrous oxide concentrations and emissions
Long-term variations of pH in coastal waters along the Korean Peninsula
Responses of microbial metabolic rates to non-equilibrated silicate vs calcium-based ocean alkalinity enhancement
Distribution of nutrients and dissolved organic matter in a eutrophic equatorial estuary: the Johor River and the East Johor Strait
Investigating the effect of silicate- and calcium-based ocean alkalinity enhancement on diatom silicification
Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment
Quantification and mitigation of bottom-trawling impacts on sedimentary organic carbon stocks in the North Sea
Influence of ocean alkalinity enhancement with olivine or steel slag on a coastal plankton community in Tasmania
Multi-model comparison of trends and controls of near-bed oxygen concentration on the northwest European continental shelf under climate change
Picoplanktonic methane production in eutrophic surface waters
Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea
Hypoxia also occurs in small highly turbid estuaries: the example of the Charente (Bay of Biscay)
Assessing the impacts of simulated Ocean Alkalinity Enhancement on viability and growth of near-shore species of phytoplankton
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
Countering the effect of ocean acidification in coastal sediments through carbonate mineral additions
Oceanographic processes driving low-oxygen conditions inside Patagonian fjords
Above- and belowground plant mercury dynamics in a salt marsh estuary in Massachusetts, USA
Variability and drivers of carbonate chemistry at shellfish aquaculture sites in the Salish Sea, British Columbia
Unusual Hemiaulus bloom influences ocean productivity in Northeastern US Shelf waters
Insights into carbonate environmental conditions in the Chukchi Sea
UAV approaches for improved mapping of vegetation cover and estimation of carbon storage of small saltmarshes: examples from Loch Fleet, northeast Scotland
Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
Marine anoxia initiates giant sulfur-oxidizing bacterial mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland
Uncertainty in the evolution of northwestern North Atlantic circulation leads to diverging biogeochemical projections
The additionality problem of ocean alkalinity enhancement
Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings
Revisiting the applicability and constraints of molybdenum- and uranium-based paleo redox proxies: comparing two contrasting sill fjords
Influence of a small submarine canyon on biogenic matter export flux in the lower St. Lawrence Estuary, eastern Canada
Single-celled bioturbators: benthic foraminifera mediate oxygen penetration and prokaryotic diversity in intertidal sediment
Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan
Multiple nitrogen sources for primary production inferred from δ13C and δ15N in the southern Sea of Japan
Influence of manganese cycling on alkalinity in the redox stratified water column of Chesapeake Bay
Estuarine flocculation dynamics of organic carbon and metals from boreal acid sulfate soils
Drivers of particle sinking velocities in the Peruvian upwelling system
Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia
Considerations for hypothetical carbon dioxide removal via alkalinity addition in the Amazon River watershed
High metabolism and periodic hypoxia associated with drifting macrophyte detritus in the shallow subtidal Baltic Sea
Production and accumulation of reef framework by calcifying corals and macroalgae on a remote Indian Ocean cay
Zooplankton community succession and trophic links during a mesocosm experiment in the coastal upwelling off Callao Bay (Peru)
Temporal and spatial evolution of bottom-water hypoxia in the St Lawrence estuarine system
Luisa Chiara Meiritz, Tim Rixen, Anja Karin van der Plas, Tarron Lamont, and Niko Lahajnar
Biogeosciences, 21, 5261–5276, https://doi.org/10.5194/bg-21-5261-2024, https://doi.org/10.5194/bg-21-5261-2024, 2024
Short summary
Short summary
Moored and drifting sediment trap experiments in the northern (nBUS) and southern (sBUS) Benguela Upwelling System showed that active carbon fluxes by vertically migrating zooplankton were about 3 times higher in the sBUS than in the nBUS. Despite these large variabilities, the mean passive particulate organic carbon (POC) fluxes were almost equal in the two subsystems. The more intense near-bottom oxygen minimum layer seems to lead to higher POC fluxes and accumulation rates in the nBUS.
Michael R. Roman, Andrew H. Altieri, Denise Breitburg, Erica M. Ferrer, Natalya D. Gallo, Shin-ichi Ito, Karin Limburg, Kenneth Rose, Moriaki Yasuhara, and Lisa A. Levin
Biogeosciences, 21, 4975–5004, https://doi.org/10.5194/bg-21-4975-2024, https://doi.org/10.5194/bg-21-4975-2024, 2024
Short summary
Short summary
Oxygen-depleted ocean waters have increased worldwide. In order to improve our understanding of the impacts of this oxygen loss on marine life it is essential that we develop reliable indicators that track the negative impacts of low oxygen. We review various indicators of low-oxygen stress for marine animals including their use, research needs, and application to confront the challenges of ocean oxygen loss.
Charlotte Eich, Mathijs van Manen, J. Scott P. McCain, Loay J. Jabre, Willem H. van de Poll, Jinyoung Jung, Sven B. E. H. Pont, Hung-An Tian, Indah Ardiningsih, Gert-Jan Reichart, Erin M. Bertrand, Corina P. D. Brussaard, and Rob Middag
Biogeosciences, 21, 4637–4663, https://doi.org/10.5194/bg-21-4637-2024, https://doi.org/10.5194/bg-21-4637-2024, 2024
Short summary
Short summary
Phytoplankton growth in the Southern Ocean (SO) is often limited by low iron (Fe) concentrations. Sea surface warming impacts Fe availability and can affect phytoplankton growth. We used shipboard Fe clean incubations to test how changes in Fe and temperature affect SO phytoplankton. Their abundances usually increased with Fe addition and temperature increase, with Fe being the major factor. These findings imply potential shifts in ecosystem structure, impacting food webs and elemental cycling.
Miriam Tivig, David P. Keller, and Andreas Oschlies
Biogeosciences, 21, 4469–4493, https://doi.org/10.5194/bg-21-4469-2024, https://doi.org/10.5194/bg-21-4469-2024, 2024
Short summary
Short summary
Marine biological production is highly dependent on the availability of nitrogen and phosphorus. Rivers are the main source of phosphorus to the oceans but poorly represented in global model oceans. We include dissolved nitrogen and phosphorus from river export in a global model ocean and find that the addition of riverine phosphorus affects marine biology on millennial timescales more than riverine nitrogen alone. Globally, riverine phosphorus input increases primary production rates.
Esdoorn Willcox, Marcos Lemes, Thomas Juul-Pedersen, Mikael Kristian Sejr, Johnna Marchiano Holding, and Søren Rysgaard
Biogeosciences, 21, 4037–4050, https://doi.org/10.5194/bg-21-4037-2024, https://doi.org/10.5194/bg-21-4037-2024, 2024
Short summary
Short summary
In this work, we measured the chemistry of seawater from samples obtained from different depths and locations off the east coast of the Northeast Greenland National Park to determine what is influencing concentrations of dissolved CO2. Historically, the region has always been thought to take up CO2 from the atmosphere, but we show that it is possible for the region to become a source in late summer. We discuss the variables that may be related to such changes.
Lennart Thomas Bach, Aaron James Ferderer, Julie LaRoche, and Kai Georg Schulz
Biogeosciences, 21, 3665–3676, https://doi.org/10.5194/bg-21-3665-2024, https://doi.org/10.5194/bg-21-3665-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement (OAE) is an emerging marine CO2 removal method, but its environmental effects are insufficiently understood. The OAE Pelagic Impact Intercomparison Project (OAEPIIP) provides funding for a standardized and globally replicated microcosm experiment to study the effects of OAE on plankton communities. Here, we provide a detailed manual for the OAEPIIP experiment. We expect OAEPIIP to help build scientific consensus on the effects of OAE on plankton.
Marlena Szeligowska, Déborah Benkort, Anna Przyborska, Mateusz Moskalik, Bernabé Moreno, Emilia Trudnowska, and Katarzyna Błachowiak-Samołyk
Biogeosciences, 21, 3617–3639, https://doi.org/10.5194/bg-21-3617-2024, https://doi.org/10.5194/bg-21-3617-2024, 2024
Short summary
Short summary
The European Arctic is experiencing rapid regional warming, causing glaciers that terminate in the sea to retreat onto land. Due to this process, the area of a well-studied fjord, Hornsund, has increased by around 100 km2 (40%) since 1976. Combining satellite and in situ data with a mathematical model, we estimated that, despite some negative consequences of glacial meltwater release, such emerging coastal waters could mitigate climate change by increasing carbon uptake and storage by sediments.
Mallory C. Ringham, Nathan Hirtle, Cody Shaw, Xi Lu, Julian Herndon, Brendan R. Carter, and Matthew D. Eisaman
Biogeosciences, 21, 3551–3570, https://doi.org/10.5194/bg-21-3551-2024, https://doi.org/10.5194/bg-21-3551-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement leverages the large surface area and carbon storage capacity of the oceans to store atmospheric CO2 as dissolved bicarbonate. We monitored CO2 uptake in seawater treated with NaOH to establish operational boundaries for carbon removal experiments. Results show that CO2 equilibration occurred on the order of weeks to months, was consistent with values expected from equilibration calculations, and was limited by mineral precipitation at high pH and CaCO3 saturation.
Riss M. Kell, Rebecca J. Chmiel, Deepa Rao, Dawn M. Moran, Matthew R. McIlvin, Tristan J. Horner, Nicole L. Schanke, Robert B. Dunbar, Giacomo R. DiTullio, and Mak A. Saito
EGUsphere, https://doi.org/10.5194/egusphere-2024-2085, https://doi.org/10.5194/egusphere-2024-2085, 2024
Short summary
Short summary
Southern Ocean phytoplankton play a pivotal role in regulating the uptake and sequestration of carbon dioxide from the atmosphere. This study describes a new stable zinc isotope uptake rate measurement method used to quantify zinc and cadmium uptake rates within native Southern Ocean phytoplankton communities. This data can better inform biogeochemical model predictions of primary production, carbon export, and atmospheric carbon dioxide flux.
Riel Carlo O. Ingeniero, Gesa Schulz, and Hermann W. Bange
Biogeosciences, 21, 3425–3440, https://doi.org/10.5194/bg-21-3425-2024, https://doi.org/10.5194/bg-21-3425-2024, 2024
Short summary
Short summary
Our research is the first to measure dissolved NO concentrations in temperate estuarine waters, providing insights into its distribution under varying conditions and enhancing our understanding of its production processes. Dissolved NO was supersaturated in the Elbe Estuary, indicating that it is a source of atmospheric NO. The observed distribution of dissolved NO most likely resulted from nitrification.
Weiyi Tang, Jeff Talbott, Timothy Jones, and Bess B. Ward
Biogeosciences, 21, 3239–3250, https://doi.org/10.5194/bg-21-3239-2024, https://doi.org/10.5194/bg-21-3239-2024, 2024
Short summary
Short summary
Wastewater treatment plants (WWTPs) are known to be hotspots of greenhouse gas emissions. However, the impact of WWTPs on the emission of the greenhouse gas N2O in downstream aquatic environments is less constrained. We found spatially and temporally variable but overall higher N2O concentrations and fluxes in waters downstream of WWTPs, pointing to the need for efficient N2O removal in addition to the treatment of nitrogen in WWTPs.
Yong-Woo Lee, Mi-Ok Park, Seong-Gil Kim, Tae-Hoon Kim, Yong-Hwa Oh, Sang Heun Lee, and Dong Joo Joung
EGUsphere, https://doi.org/10.5194/egusphere-2024-1836, https://doi.org/10.5194/egusphere-2024-1836, 2024
Short summary
Short summary
A long-term pH variation in coastal waters along the Korean peninsula was assessed for the first time, and it exhibited no significant pH change over an 11-year period. This contrasts with the ongoing pH decline in open oceans and other coastal areas. Analysis of environmental data showed that pH is mainly controlled by dissolved oxygen in bottom waters. This suggests that ocean warming could cause a pH decline in Korean coastal waters, affecting many fish and seaweeds aquaculture operations.
Laura Marin-Samper, Javier Arístegui, Nauzet Hernández-Hernández, and Ulf Riebesell
EGUsphere, https://doi.org/10.5194/egusphere-2024-1776, https://doi.org/10.5194/egusphere-2024-1776, 2024
Short summary
Short summary
This study exposed a natural community to two non-CO2 equilibrated ocean alkalinity enhancement (OAE) deployments using different minerals. Adding alkalinity in this manner decreases dissolved CO2, essential for photosynthesis. While photosynthesis was not suppressed, bloom formation was delayed, potentially impacting marine food webs. The study emphasizes the need for further research on OAE without prior equilibration and its ecological implications
Amanda Y. L. Cheong, Kogila Vani Annammala, Ee Ling Yong, Yongli Zhou, Robert S. Nichols, and Patrick Martin
Biogeosciences, 21, 2955–2971, https://doi.org/10.5194/bg-21-2955-2024, https://doi.org/10.5194/bg-21-2955-2024, 2024
Short summary
Short summary
We measured nutrients and dissolved organic matter for 1 year in a eutrophic tropical estuary to understand their sources and cycling. Our data show that the dissolved organic matter originates partly from land and partly from microbial processes in the water. Internal recycling is likely important for maintaining high nutrient concentrations, and we found that there is often excess nitrogen compared to silicon and phosphorus. Our data help to explain how eutrophication persists in this system.
Aaron Ferderer, Kai G. Schulz, Ulf Riebesell, Kirralee G. Baker, Zanna Chase, and Lennart T. Bach
Biogeosciences, 21, 2777–2794, https://doi.org/10.5194/bg-21-2777-2024, https://doi.org/10.5194/bg-21-2777-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement (OAE) is a promising method of atmospheric carbon removal; however, its ecological impacts remain largely unknown. We assessed the effects of simulated silicate- and calcium-based mineral OAE on diatom silicification. We found that increased silicate concentrations from silicate-based OAE increased diatom silicification. In contrast, the enhancement of alkalinity had no effect on community silicification and minimal effects on the silicification of different genera.
David González-Santana, María Segovia, Melchor González-Dávila, Librada Ramírez, Aridane G. González, Leonardo J. Pozzo-Pirotta, Veronica Arnone, Victor Vázquez, Ulf Riebesell, and J. Magdalena Santana-Casiano
Biogeosciences, 21, 2705–2715, https://doi.org/10.5194/bg-21-2705-2024, https://doi.org/10.5194/bg-21-2705-2024, 2024
Short summary
Short summary
In a recent experiment off the coast of Gran Canaria (Spain), scientists explored a method called ocean alkalinization enhancement (OAE), where carbonate minerals were added to seawater. This process changed the levels of certain ions in the water, affecting its pH and buffering capacity. The researchers were particularly interested in how this could impact the levels of essential trace metals in the water.
Lucas Porz, Wenyan Zhang, Nils Christiansen, Jan Kossack, Ute Daewel, and Corinna Schrum
Biogeosciences, 21, 2547–2570, https://doi.org/10.5194/bg-21-2547-2024, https://doi.org/10.5194/bg-21-2547-2024, 2024
Short summary
Short summary
Seafloor sediments store a large amount of carbon, helping to naturally regulate Earth's climate. If disturbed, some sediment particles can turn into CO2, but this effect is not well understood. Using computer simulations, we found that bottom-contacting fishing gears release about 1 million tons of CO2 per year in the North Sea, one of the most heavily fished regions globally. We show how protecting certain areas could reduce these emissions while also benefitting seafloor-living animals.
Jiaying A. Guo, Robert F. Strzepek, Kerrie M. Swadling, Ashley T. Townsend, and Lennart T. Bach
Biogeosciences, 21, 2335–2354, https://doi.org/10.5194/bg-21-2335-2024, https://doi.org/10.5194/bg-21-2335-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement aims to increase atmospheric CO2 sequestration by adding alkaline materials to the ocean. We assessed the environmental effects of olivine and steel slag powder on coastal plankton. Overall, slag is more efficient than olivine in releasing total alkalinity and, thus, in its ability to sequester CO2. Slag also had less environmental effect on the enclosed plankton communities when considering its higher CO2 removal potential based on this 3-week experiment.
Giovanni Galli, Sarah Wakelin, James Harle, Jason Holt, and Yuri Artioli
Biogeosciences, 21, 2143–2158, https://doi.org/10.5194/bg-21-2143-2024, https://doi.org/10.5194/bg-21-2143-2024, 2024
Short summary
Short summary
This work shows that, under a high-emission scenario, oxygen concentration in deep water of parts of the North Sea and Celtic Sea can become critically low (hypoxia) towards the end of this century. The extent and frequency of hypoxia depends on the intensity of climate change projected by different climate models. This is the result of a complex combination of factors like warming, increase in stratification, changes in the currents and changes in biological processes.
Sandy E. Tenorio and Laura Farías
Biogeosciences, 21, 2029–2050, https://doi.org/10.5194/bg-21-2029-2024, https://doi.org/10.5194/bg-21-2029-2024, 2024
Short summary
Short summary
Time series studies show that CH4 is highly dynamic on the coastal ocean surface and planktonic communities are linked to CH4 accumulation, as found in coastal upwelling off Chile. We have identified the crucial role of picoplankton (> 3 µm) in CH4 recycling, especially with the addition of methylated substrates (trimethylamine and methylphosphonic acid) during upwelling and non-upwelling periods. These insights improve understanding of surface ocean CH4 recycling, aiding CH4 emission estimates.
Charlotte A. J. Williams, Tom Hull, Jan Kaiser, Claire Mahaffey, Naomi Greenwood, Matthew Toberman, and Matthew R. Palmer
Biogeosciences, 21, 1961–1971, https://doi.org/10.5194/bg-21-1961-2024, https://doi.org/10.5194/bg-21-1961-2024, 2024
Short summary
Short summary
Oxygen (O2) is a key indicator of ocean health. The risk of O2 loss in the productive coastal/continental slope regions is increasing. Autonomous underwater vehicles equipped with O2 optodes provide lots of data but have problems resolving strong vertical O2 changes. Here we show how to overcome this and calculate how much O2 is supplied to the low-O2 bottom waters via mixing. Bursts in mixing supply nearly all of the O2 to bottom waters in autumn, stopping them reaching ecologically low levels.
Sabine Schmidt and Ibrahima Iris Diallo
Biogeosciences, 21, 1785–1800, https://doi.org/10.5194/bg-21-1785-2024, https://doi.org/10.5194/bg-21-1785-2024, 2024
Short summary
Short summary
Along the French coast facing the Bay of Biscay, the large Gironde and Loire estuaries suffer from hypoxia. This prompted a study of the small Charente estuary located between them. This work reveals a minimum oxygen zone in the Charente estuary, which extends for about 25 km. Temperature is the main factor controlling the hypoxia. This calls for the monitoring of small turbid macrotidal estuaries that are vulnerable to hypoxia, a risk expected to increase with global warming.
Jessica L. Oberlander, Mackenzie E. Burke, Cat A. London, and Hugh L. MacIntyre
EGUsphere, https://doi.org/10.5194/egusphere-2024-971, https://doi.org/10.5194/egusphere-2024-971, 2024
Short summary
Short summary
OAE is a promising negative emission technology that could restore the oceanic pH and carbonate system to a pre-industrial state. To our knowledge, this paper is the first to assess the potential impact of OAE on phytoplankton through an analysis of prior studies and the effects of simulated OAE on photosynthetic competence. Our findings suggest that there may be little if any significant impact on most phytoplankton studied to date if OAE is conducted in well-flushed, near-shore environments.
Simone R. Alin, Jan A. Newton, Richard A. Feely, Samantha Siedlecki, and Dana Greeley
Biogeosciences, 21, 1639–1673, https://doi.org/10.5194/bg-21-1639-2024, https://doi.org/10.5194/bg-21-1639-2024, 2024
Short summary
Short summary
We provide a new multi-stressor data product that allows us to characterize the seasonality of temperature, O2, and CO2 in the southern Salish Sea and delivers insights into the impacts of major marine heatwave and precipitation anomalies on regional ocean acidification and hypoxia. We also describe the present-day frequencies of temperature, O2, and ocean acidification conditions that cross thresholds of sensitive regional species that are economically or ecologically important.
Kadir Bice, Tristen Myers, George Waldbusser, and Christof Meile
EGUsphere, https://doi.org/10.5194/egusphere-2024-796, https://doi.org/10.5194/egusphere-2024-796, 2024
Short summary
Short summary
We studied the effect of addition of carbonate minerals on coastal sediments, We carried out laboratory experiments to quantify the dissolution kinetics and integrated these observations into a numerical model that describes biogeochemical cycling in surficial sediments. Using the model, we demonstrate the buffering effect of the mineral additions and its duration. We quantify the effect under different environmental conditions and assess the potential for increased atmospheric CO2 uptake.
Pamela Linford, Iván Pérez-Santos, Paulina Montero, Patricio A. Díaz, Claudia Aracena, Elías Pinilla, Facundo Barrera, Manuel Castillo, Aida Alvera-Azcárate, Mónica Alvarado, Gabriel Soto, Cécile Pujol, Camila Schwerter, Sara Arenas-Uribe, Pilar Navarro, Guido Mancilla-Gutiérrez, Robinson Altamirano, Javiera San Martín, and Camila Soto-Riquelme
Biogeosciences, 21, 1433–1459, https://doi.org/10.5194/bg-21-1433-2024, https://doi.org/10.5194/bg-21-1433-2024, 2024
Short summary
Short summary
The Patagonian fjords comprise a world region where low-oxygen water and hypoxia conditions are observed. An in situ dataset was used to quantify the mechanism involved in the presence of these conditions in northern Patagonian fjords. Water mass analysis confirmed the contribution of Equatorial Subsurface Water in the advection of the low-oxygen water, and hypoxic conditions occurred when the community respiration rate exceeded the gross primary production.
Ting Wang, Buyun Du, Inke Forbrich, Jun Zhou, Joshua Polen, Elsie M. Sunderland, Prentiss H. Balcom, Celia Chen, and Daniel Obrist
Biogeosciences, 21, 1461–1476, https://doi.org/10.5194/bg-21-1461-2024, https://doi.org/10.5194/bg-21-1461-2024, 2024
Short summary
Short summary
The strong seasonal increases of Hg in aboveground biomass during the growing season and the lack of changes observed after senescence in this salt marsh ecosystem suggest physiologically controlled Hg uptake pathways. The Hg sources found in marsh aboveground tissues originate from a mix of sources, unlike terrestrial ecosystems, where atmospheric GEM is the main source. Belowground plant tissues mostly take up Hg from soils. Overall, the salt marsh currently serves as a small net Hg sink.
Eleanor Simpson, Debby Ianson, Karen E. Kohfeld, Ana C. Franco, Paul A. Covert, Marty Davelaar, and Yves Perreault
Biogeosciences, 21, 1323–1353, https://doi.org/10.5194/bg-21-1323-2024, https://doi.org/10.5194/bg-21-1323-2024, 2024
Short summary
Short summary
Shellfish aquaculture operates in nearshore areas where data on ocean acidification parameters are limited. We show daily and seasonal variability in pH and saturation states of calcium carbonate at nearshore aquaculture sites in British Columbia, Canada, and determine the contributing drivers of this variability. We find that nearshore locations have greater variability than open waters and that the uptake of carbon by phytoplankton is the major driver of pH and saturation state variability.
S. Alejandra Castillo Cieza, Rachel H. R. Stanley, Pierre Marrec, Diana N. Fontaine, E. Taylor Crockford, Dennis J. McGillicuddy Jr., Arshia Mehta, Susanne Menden-Deuer, Emily E. Peacock, Tatiana A. Rynearson, Zoe O. Sandwith, Weifeng Zhang, and Heidi M. Sosik
Biogeosciences, 21, 1235–1257, https://doi.org/10.5194/bg-21-1235-2024, https://doi.org/10.5194/bg-21-1235-2024, 2024
Short summary
Short summary
The coastal ocean in the northeastern USA provides many services, including fisheries and habitats for threatened species. In summer 2019, a bloom occurred of a large unusual phytoplankton, the diatom Hemiaulus, with nitrogen-fixing symbionts. This led to vast changes in productivity and grazing rates in the ecosystem. This work shows that the emergence of one species can have profound effects on ecosystem function. Such changes may become more prevalent as the ocean warms due to climate change.
Claudine Hauri, Brita Irving, Sam Dupont, Rémi Pagés, Donna D. W. Hauser, and Seth L. Danielson
Biogeosciences, 21, 1135–1159, https://doi.org/10.5194/bg-21-1135-2024, https://doi.org/10.5194/bg-21-1135-2024, 2024
Short summary
Short summary
Arctic marine ecosystems are highly susceptible to impacts of climate change and ocean acidification. We present pH and pCO2 time series (2016–2020) from the Chukchi Ecosystem Observatory and analyze the drivers of the current conditions to get a better understanding of how climate change and ocean acidification could affect the ecological niches of organisms.
William Hiles, Lucy C. Miller, Craig Smeaton, and William E. N. Austin
Biogeosciences, 21, 929–948, https://doi.org/10.5194/bg-21-929-2024, https://doi.org/10.5194/bg-21-929-2024, 2024
Short summary
Short summary
Saltmarsh soils may help to limit the rate of climate change by storing carbon. To understand their impacts, they must be accurately mapped. We use drone data to estimate the size of three saltmarshes in NE Scotland. We find that drone imagery, combined with tidal data, can reliably inform our understanding of saltmarsh size. When compared with previous work using vegetation communities, we find that our most reliable new estimates of stored carbon are 15–20 % smaller than previously estimated.
De'Marcus Robinson, Anh L. D. Pham, David J. Yousavich, Felix Janssen, Frank Wenzhöfer, Eleanor C. Arrington, Kelsey M. Gosselin, Marco Sandoval-Belmar, Matthew Mar, David L. Valentine, Daniele Bianchi, and Tina Treude
Biogeosciences, 21, 773–788, https://doi.org/10.5194/bg-21-773-2024, https://doi.org/10.5194/bg-21-773-2024, 2024
Short summary
Short summary
The present study suggests that high release of ferrous iron from the seafloor of the oxygen-deficient Santa Barabara Basin (California) supports surface primary productivity, creating positive feedback on seafloor iron release by enhancing low-oxygen conditions in the basin.
David J. Yousavich, De'Marcus Robinson, Xuefeng Peng, Sebastian J. E. Krause, Frank Wenzhöfer, Felix Janssen, Na Liu, Jonathan Tarn, Franklin Kinnaman, David L. Valentine, and Tina Treude
Biogeosciences, 21, 789–809, https://doi.org/10.5194/bg-21-789-2024, https://doi.org/10.5194/bg-21-789-2024, 2024
Short summary
Short summary
Declining oxygen (O2) concentrations in coastal oceans can threaten people’s ways of life and food supplies. Here, we investigate how mats of bacteria that proliferate on the seafloor of the Santa Barbara Basin sustain and potentially worsen these O2 depletion events through their unique chemoautotrophic metabolism. Our study shows how changes in seafloor microbiology and geochemistry brought on by declining O2 concentrations can help these mats grow as well as how that growth affects the basin.
Krysten Rutherford, Katja Fennel, Lina Garcia Suarez, and Jasmin G. John
Biogeosciences, 21, 301–314, https://doi.org/10.5194/bg-21-301-2024, https://doi.org/10.5194/bg-21-301-2024, 2024
Short summary
Short summary
We downscaled two mid-century (~2075) ocean model projections to a high-resolution regional ocean model of the northwest North Atlantic (NA) shelf. In one projection, the NA shelf break current practically disappears; in the other it remains almost unchanged. This leads to a wide range of possible future shelf properties. More accurate projections of coastal circulation features would narrow the range of possible outcomes of biogeochemical projections for shelf regions.
Lennart Thomas Bach
Biogeosciences, 21, 261–277, https://doi.org/10.5194/bg-21-261-2024, https://doi.org/10.5194/bg-21-261-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement (OAE) is a widely considered marine carbon dioxide removal method. OAE aims to accelerate chemical rock weathering, which is a natural process that slowly sequesters atmospheric carbon dioxide. This study shows that the addition of anthropogenic alkalinity via OAE can reduce the natural release of alkalinity and, therefore, reduce the efficiency of OAE for climate mitigation. However, the additionality problem could be mitigated via a variety of activities.
Tsuneo Ono, Daisuke Muraoka, Masahiro Hayashi, Makiko Yorifuji, Akihiro Dazai, Shigeyuki Omoto, Takehiro Tanaka, Tomohiro Okamura, Goh Onitsuka, Kenji Sudo, Masahiko Fujii, Ryuji Hamanoue, and Masahide Wakita
Biogeosciences, 21, 177–199, https://doi.org/10.5194/bg-21-177-2024, https://doi.org/10.5194/bg-21-177-2024, 2024
Short summary
Short summary
We carried out parallel year-round observations of pH and related parameters in five stations around the Japan coast. It was found that short-term acidified situations with Omega_ar less than 1.5 occurred at four of five stations. Most of such short-term acidified events were related to the short-term low salinity event, and the extent of short-term pH drawdown at high freshwater input was positively correlated with the nutrient concentration of the main rivers that flow into the coastal area.
K. Mareike Paul, Martijn Hermans, Sami A. Jokinen, Inda Brinkmann, Helena L. Filipsson, and Tom Jilbert
Biogeosciences, 20, 5003–5028, https://doi.org/10.5194/bg-20-5003-2023, https://doi.org/10.5194/bg-20-5003-2023, 2023
Short summary
Short summary
Seawater naturally contains trace metals such as Mo and U, which accumulate under low oxygen conditions on the seafloor. Previous studies have used sediment Mo and U contents as an archive of changing oxygen concentrations in coastal waters. Here we show that in fjords the use of Mo and U for this purpose may be impaired by additional processes. Our findings have implications for the reliable use of Mo and U to reconstruct oxygen changes in fjords.
Hannah Sharpe, Michel Gosselin, Catherine Lalande, Alexandre Normandeau, Jean-Carlos Montero-Serrano, Khouloud Baccara, Daniel Bourgault, Owen Sherwood, and Audrey Limoges
Biogeosciences, 20, 4981–5001, https://doi.org/10.5194/bg-20-4981-2023, https://doi.org/10.5194/bg-20-4981-2023, 2023
Short summary
Short summary
We studied the impact of submarine canyon processes within the Pointe-des-Monts system on biogenic matter export and phytoplankton assemblages. Using data from three oceanographic moorings, we show that the canyon experienced two low-amplitude sediment remobilization events in 2020–2021 that led to enhanced particle fluxes in the deep-water column layer > 2.6 km offshore. Sinking phytoplankton fluxes were lower near the canyon compared to background values from the lower St. Lawrence Estuary.
Dewi Langlet, Florian Mermillod-Blondin, Noémie Deldicq, Arthur Bauville, Gwendoline Duong, Lara Konecny, Mylène Hugoni, Lionel Denis, and Vincent M. P. Bouchet
Biogeosciences, 20, 4875–4891, https://doi.org/10.5194/bg-20-4875-2023, https://doi.org/10.5194/bg-20-4875-2023, 2023
Short summary
Short summary
Benthic foraminifera are single-cell marine organisms which can move in the sediment column. They were previously reported to horizontally and vertically transport sediment particles, yet the impact of their motion on the dissolved fluxes remains unknown. Using microprofiling, we show here that foraminiferal burrow formation increases the oxygen penetration depth in the sediment, leading to a change in the structure of the prokaryotic community.
Masahiko Fujii, Ryuji Hamanoue, Lawrence Patrick Cases Bernardo, Tsuneo Ono, Akihiro Dazai, Shigeyuki Oomoto, Masahide Wakita, and Takehiro Tanaka
Biogeosciences, 20, 4527–4549, https://doi.org/10.5194/bg-20-4527-2023, https://doi.org/10.5194/bg-20-4527-2023, 2023
Short summary
Short summary
This is the first study of the current and future impacts of climate change on Pacific oyster farming in Japan. Future coastal warming and acidification may affect oyster larvae as a result of longer exposure to lower-pH waters. A prolonged spawning period may harm oyster processing by shortening the shipping period and reducing oyster quality. To minimize impacts on Pacific oyster farming, in addition to mitigation measures, local adaptation measures may be required.
Taketoshi Kodama, Atsushi Nishimoto, Ken-ichi Nakamura, Misato Nakae, Naoki Iguchi, Yosuke Igeta, and Yoichi Kogure
Biogeosciences, 20, 3667–3682, https://doi.org/10.5194/bg-20-3667-2023, https://doi.org/10.5194/bg-20-3667-2023, 2023
Short summary
Short summary
Carbon and nitrogen are essential elements for organisms; their stable isotope ratios (13C : 12C, 15N : 14N) are useful tools for understanding turnover and movement in the ocean. In the Sea of Japan, the environment is rapidly being altered by human activities. The 13C : 12C of small organic particles is increased by active carbon fixation, and phytoplankton growth increases the values. The 15N : 14N variations suggest that nitrates from many sources contribute to organic production.
Aubin Thibault de Chanvalon, George W. Luther, Emily R. Estes, Jennifer Necker, Bradley M. Tebo, Jianzhong Su, and Wei-Jun Cai
Biogeosciences, 20, 3053–3071, https://doi.org/10.5194/bg-20-3053-2023, https://doi.org/10.5194/bg-20-3053-2023, 2023
Short summary
Short summary
The intensity of the oceanic trap of CO2 released by anthropogenic activities depends on the alkalinity brought by continental weathering. Between ocean and continent, coastal water and estuaries can limit or favour the alkalinity transfer. This study investigate new interactions between dissolved metals and alkalinity in the oxygen-depleted zone of estuaries.
Joonas J. Virtasalo, Peter Österholm, and Eero Asmala
Biogeosciences, 20, 2883–2901, https://doi.org/10.5194/bg-20-2883-2023, https://doi.org/10.5194/bg-20-2883-2023, 2023
Short summary
Short summary
We mixed acidic metal-rich river water from acid sulfate soils and seawater in the laboratory to study the flocculation of dissolved metals and organic matter in estuaries. Al and Fe flocculated already at a salinity of 0–2 to large organic flocs (>80 µm size). Precipitation of Al and Fe hydroxide flocculi (median size 11 µm) began when pH exceeded ca. 5.5. Mn transferred weakly to Mn hydroxides and Co to the flocs. Up to 50 % of Cu was associated with the flocs, irrespective of seawater mixing.
Moritz Baumann, Allanah Joy Paul, Jan Taucher, Lennart Thomas Bach, Silvan Goldenberg, Paul Stange, Fabrizio Minutolo, and Ulf Riebesell
Biogeosciences, 20, 2595–2612, https://doi.org/10.5194/bg-20-2595-2023, https://doi.org/10.5194/bg-20-2595-2023, 2023
Short summary
Short summary
The sinking velocity of marine particles affects how much atmospheric CO2 is stored inside our oceans. We measured particle sinking velocities in the Peruvian upwelling system and assessed their physical and biochemical drivers. We found that sinking velocity was mainly influenced by particle size and porosity, while ballasting minerals played only a minor role. Our findings help us to better understand the particle sinking dynamics in this highly productive marine system.
Kyle E. Hinson, Marjorie A. M. Friedrichs, Raymond G. Najjar, Maria Herrmann, Zihao Bian, Gopal Bhatt, Pierre St-Laurent, Hanqin Tian, and Gary Shenk
Biogeosciences, 20, 1937–1961, https://doi.org/10.5194/bg-20-1937-2023, https://doi.org/10.5194/bg-20-1937-2023, 2023
Short summary
Short summary
Climate impacts are essential for environmental managers to consider when implementing nutrient reduction plans designed to reduce hypoxia. This work highlights relative sources of uncertainty in modeling regional climate impacts on the Chesapeake Bay watershed and consequent declines in bay oxygen levels. The results demonstrate that planned water quality improvement goals are capable of reducing hypoxia levels by half, offsetting climate-driven impacts on terrestrial runoff.
Linquan Mu, Jaime B. Palter, and Hongjie Wang
Biogeosciences, 20, 1963–1977, https://doi.org/10.5194/bg-20-1963-2023, https://doi.org/10.5194/bg-20-1963-2023, 2023
Short summary
Short summary
Enhancing ocean alkalinity accelerates carbon dioxide removal from the atmosphere. We hypothetically added alkalinity to the Amazon River and examined the increment of the carbon uptake by the Amazon plume. We also investigated the minimum alkalinity addition in which this perturbation at the river mouth could be detected above the natural variability.
Karl M. Attard, Anna Lyssenko, and Iván F. Rodil
Biogeosciences, 20, 1713–1724, https://doi.org/10.5194/bg-20-1713-2023, https://doi.org/10.5194/bg-20-1713-2023, 2023
Short summary
Short summary
Aquatic plants produce a large amount of organic matter through photosynthesis that, following erosion, is deposited on the seafloor. In this study, we show that plant detritus can trigger low-oxygen conditions (hypoxia) in shallow coastal waters, making conditions challenging for most marine animals. We propose that the occurrence of hypoxia may be underestimated because measurements typically do not consider the region closest to the seafloor, where detritus accumulates.
M. James McLaughlin, Cindy Bessey, Gary A. Kendrick, John Keesing, and Ylva S. Olsen
Biogeosciences, 20, 1011–1026, https://doi.org/10.5194/bg-20-1011-2023, https://doi.org/10.5194/bg-20-1011-2023, 2023
Short summary
Short summary
Coral reefs face increasing pressures from environmental change at present. The coral reef framework is produced by corals and calcifying algae. The Kimberley region of Western Australia has escaped land-based anthropogenic impacts. Specimens of the dominant coral and algae were collected from Browse Island's reef platform and incubated in mesocosms to measure calcification and production patterns of oxygen. This study provides important data on reef building and climate-driven effects.
Patricia Ayón Dejo, Elda Luz Pinedo Arteaga, Anna Schukat, Jan Taucher, Rainer Kiko, Helena Hauss, Sabrina Dorschner, Wilhelm Hagen, Mariona Segura-Noguera, and Silke Lischka
Biogeosciences, 20, 945–969, https://doi.org/10.5194/bg-20-945-2023, https://doi.org/10.5194/bg-20-945-2023, 2023
Short summary
Short summary
Ocean upwelling regions are highly productive. With ocean warming, severe changes in upwelling frequency and/or intensity and expansion of accompanying oxygen minimum zones are projected. In a field experiment off Peru, we investigated how different upwelling intensities affect the pelagic food web and found failed reproduction of dominant zooplankton. The changes projected could severely impact the reproductive success of zooplankton communities and the pelagic food web in upwelling regions.
Mathilde Jutras, Alfonso Mucci, Gwenaëlle Chaillou, William A. Nesbitt, and Douglas W. R. Wallace
Biogeosciences, 20, 839–849, https://doi.org/10.5194/bg-20-839-2023, https://doi.org/10.5194/bg-20-839-2023, 2023
Short summary
Short summary
The deep waters of the lower St Lawrence Estuary and gulf have, in the last decades, experienced a strong decline in their oxygen concentration. Below 65 µmol L-1, the waters are said to be hypoxic, with dire consequences for marine life. We show that the extent of the hypoxic zone shows a seven-fold increase in the last 20 years, reaching 9400 km2 in 2021. After a stable period at ~ 65 µmol L⁻¹ from 1984 to 2019, the oxygen level also suddenly decreased to ~ 35 µmol L-1 in 2020.
Cited articles
Agawin, N. S. and Duarte, C. M.: Evidence of direct particle trapping by a
tropical seagrass meadow, Estuaries, 25, 1205–1209, https://doi.org/10.1007/BF02692217,
2002.
Barron, C., Marba, N., Terrados, J., Kennedy, H., and Duarte, C. M.:
Community metabolism and carbon budget along a gradient of seagrass
(Cymodocea nodosa) colonization, Limnol. Oceanogr., 49, 1642–1651,
https://doi.org/10.4319/lo.2004.49.5.1642, 2004.
Borum, J., Sand-Jensen, K., Binzer, T., Pedersen, O., and Greve, T. M.: Oxygen
movement in seagrasses, in: Seagrasses: biology, ecology and conservation,
edited by: Larkum, A. W. D., Orth, R. J., and Duarte, C. M., Springer, Dordrecht, 255–270,
2006.
Cebrian, J., Pedersen, M. F., Kroeger, K. D., and Valiela, I.: Fate of
production of the seagrass Cymodocea nodosa in different stages of meadow
formation, Mar. Ecol.-Prog. Ser., 204, 119–130, https://doi.org/10.3354/meps204119,
2000.
Dahl, M., Deyanova, D., Lyimo, L. D., Näslund, J., Samuelsson, G. S.,
Mtolera, M. S. P., Björk, M., and Gullström, M.: Effects of shading
and simulated grazing on carbon sequestration in a tropical seagrass meadow,
J. Ecol., 104, 654–664, https://doi.org/10.1111/1365-2745.12564, 2016.
Duarte, C. M. and Chiscano, C. L.: Seagrass biomass and production: a
reassessment, Aquat. Bot., 65, 159–174, https://doi.org/10.1016/S0304-3770(99)00038-8,
1999.
Duarte, C. M., Merino, M., Agawin, N. S., Uri, J., Fortes, M. D., Gallegos,
M. E., Marbà, N., and Hemminga, M. A.: Root production and belowground
seagrass biomass, Mar. Ecol.-Prog. Ser., 171, 97–108, https://doi.org/10.3354/meps171097, 1998.
Duarte, C. M., Benavent, E., and del Carmen Sanchez, M.: The microcosm of
particles within seagrass Posidonia oceanica canopies, Mar. Ecol.-Prog.
Ser., 181, 289–295, https://doi.org/10.3354/meps181289, 1999.
Duarte, C. M., Marbà, N., Gacia, E., Fourqurean, J. W., Beggins, J.,
Barrón, C., and Apostolaki, E. T.: Seagrass community metabolism:
Assessing the carbon sink capacity of seagrass meadows, Global Biogeochem.
Cy., 24, GB4032, https://doi.org/10.1029/2010GB003793, 2010.
Duarte, C. M., Kennedy, H., Marba, N., and Hendriks, I.: Assessing the
capacity of seagrass meadows for carbon burial: current limitations and
future strategies, Ocean. Coast. Manage., 83, 32–38, https://doi.org/10.1016/j.ocecoaman.2011.09.001, 2013.
Erftemeijer, P. L., Osinga, R., and Mars, A. E.: Primary production of
seagrass beds in South Sulawesi (Indonesia): a comparison of habitats,
methods and species, Aquat. Bot., 46, 67–90, https://doi.org/10.1016/0304-3770(93)90065-5, 1993.
Fonseca, M. S. and Bell, S. S.: Influence of physical setting on seagrass
landscapes near Beaufort, North Carolina, USA, Mar. Ecol.-Prog. Ser., 171,
109–121, https://doi.org/10.3354/meps171109, 1998.
Fourqurean, J. W. and Schrlau, J. E.: Changes in nutrient content and stable
ratios of C and N during decomposition of seagrasses and mangrove leaves
along a nutrient availability gradient in Florida bay, USA, Chem. Ecol., 19,
373–390, https://doi.org/10.1080/02757540310001609370, 2003.
Fourqurean, J. W., Duarte, C. M., Kennedy, H., Marbà, N., Holmer, M.,
Mateo, M. A., Apostolaki, E. T., Kendrick, G. A., Krause-Jensen, D.,
McGlathery, K. J., and Serrano, O.: Seagrass ecosystems as a globally
significant carbon stock, Nat. Geosci., 5, 505–509, https://doi.org/10.1038/ngeo1477,
2012.
Gacia, E. and Duarte, C. M.: Sediment retention by a Mediterranean Posidonia
oceanica meadow: the balance between deposition and resuspension, Estuar.
Coast. Shelf S., 52, 505–514, https://doi.org/10.1006/ecss.2000.0753, 2001.
Gacia, E., Granata T. C., and Duarte, C. M.: An approach to measurement of
particle flux and sediment retention within seagrass (Posidonia oceanica)
meadows, Aquat. Bot., 65, 255–268, https://doi.org/10.1016/S0304-3770(99)00044-3, 1999.
Gacia, E., Duarte, C. M., Marba, N., Terrados, J., Kennedy, H., Fortes, M.
D., and Tri, N. H.: Sediment deposition and production in SE-Asia seagrass
meadows, Estuar. Coast. Shelf S., 56, 909–919,
https://doi.org/10.1016/S0272-7714(02)00286-X, 2003.
Green, E. P. and Short, F. T. (Eds.): World atlas of seagrasses, University
of California Press, Berkeley, 2003.
Hemminga, M. A., Slim, F. J., Kazungu, J., Ganssen, G. M., Nieuwenhuize, J.,
and Kruyt, N. M.: Carbon outwelling from a mangrove forest with adjacent
seagrass beds and coral reefs (Gazi Bay, Kenya), Mar. Ecol.-Prog. Ser., 106,
291–301, https://doi.org/10.3354/meps106291, 1994.
Hendriks, I. E., Sintes, T., Bouma, T. J., and Duarte, C. M.: Experimental
assessment and modeling evaluation of the effects of the seagrass Posidonia
oceanica on flow and particle trapping, Mar. Ecol.-Prog. Ser., 356, 163–173,
https://doi.org/10.3354/meps07316, 2008.
Holmer, M. and Olsen, A. B.: Role of decomposition of mangrove and seagrass
detritus in sediment carbon and nitrogen cycling in a tropical mangrove
forest, Mar. Ecol.-Prog. Ser., 230, 87–101, https://doi.org/10.3354/meps230087, 2002.
Howard, J. L., Creed, J. C., Aguiar, M. V. P., and Fouqurean, J. W.:
CO2 released by carbonate sediment production in some coastal
areas may offset the benefits of seagrass “Blue Carbon” storage,
Limnol. Oceanogr., 63, 160–172, https://doi.org/10.1002/lno.10621, 2018.
Ingalls, A. E., Lee, C., and Druffel, E. R.: Preservation of organic matter
in mound-forming coral skeletons, Geochim. Cosmochim. Ac., 67, 2827–2841,
https://doi.org/10.1016/S0016-7037(03)00079-6, 2003.
Kennedy, H., Gacia, E., Kennedy, D. P., Papadimitriou, S., and Duarte, C. M.:
Organic carbon sources to SE Asian coastal sediments, Estuar. Coast. Shelf
S., 60, 59–68, https://doi.org/10.1016/j.ecss.2003.11.019, 2004.
Kennedy, H., Beggins, J., Duarte, C. M., Fourqurean, J. W., Holmer, M.,
Marbà, N., and Middelburg, J. J.: Seagrass sediments as a global carbon
sink: isotopic constraints, Global Biogeochem. Cy., 24, GB4026, https://doi.org/10.1029/2010GB003848, 2010.
Kirkman, H.: Seagrasses of Australia. State of the Environment Technical
Paper Series (Estuaries and the Sea), Department of the Environment,
Canberra, 1997.
Koch, E. W.: Beyond light: physical, geological, and geochemical parameters
as possible submersed aquatic vegetation habitat
requirements, Estuaries, 24, 1–17, https://doi.org/10.2307/1352808, 2001.
Kuwae, T., Beninger, P. G., Decottignies, P., Mathot, K. J., Lund, D. R.,
and Elner, R. W.: Biofilm grazing in a higher vertebrate: the western
sandpiper, Calidris mauri, Ecology, 89, 599–606, https://doi.org/10.1890/07-1442.1,
2008.
Lavery, P. S., Mateo, M.-A., Serrano, O., and Rozaimi, M.: Variability in the
Carbon Storage of Seagrass Habitats and Its Implications for Global
Estimates of Blue Carbon Ecosystem Service, PLOS ONE, 8, e73748, https://doi.org/10.1371/journal.pone.0073748, 2013.
Lee, K. S., Park, S. R., and Kim, Y. K.: Effects of irradiance, temperature,
and nutrients on growth dynamics of seagrasses: a review, J. Exp. Mar. Biol.
Ecol., 350, 144–175, https://doi.org/10.1016/j.jembe.2007.06.016, 2007.
Mcleod, E., Chmura, G. L., Bouillon, S., Salm, R., Björk, M., Duarte, C.
M., Lovelock, C. E., Schlesinger, W. H., and Silliman, B. R.: A blueprint for
blue carbon: toward an improved understanding of the role of vegetated
coastal habitats in sequestering CO2, Front. Ecol. Environ., 9,
552–560, https://doi.org/10.1890/110004, 2011.
Mitsumoto, H., Omija, T., and Kobayashi, R.: Water pollution caused by soil
run-off and the coral reef situation in Shiraho, Ishigaki Island 2, Annual
Report of Okinawa Prefectural Institute of Health and Environment, 34,
121–124, 2000 (in Japanese).
Miyajima, T., Koike, I., Yamano, H., and Iizumi, H.: Accumulation and
transport of seagrass-derived organic matter in reef flat sediment of Green
Island, Great Barrier Reef, Mar. Ecol.-Prog. Ser., 175, 251–259, https://doi.org/10.3354/meps175251, 1998.
Miyajima, T., Hori, M., Hamaguchi, M., Shimabukuro, H., Adachi, H., Yamano,
H., and Nakaoka, M.: Geographic variability in organic carbon stock and
accumulation rate in sediments of East and Southeast Asian seagrass
meadows, Global Biogeochem. Cy., 29, 397–415, https://doi.org/10.1002/2014GB004979,
2015.
Miyajima, T., Hori, M., Hamaguchi, M., Shimabukuro, H., and Yoshida, G.:
Geophysical constraints for organic carbon sequestration capacity of Zostera
marina seagrass meadows and surrounding habitats, Limnol. Oceanogr., 62,
954–972, https://doi.org/10.1002/lno.10478, 2017.
Nakamura, T. and Nakamori, T.: Estimation of photosynthesis and
calcification rates at a fringing reef by accounting for diurnal variations
and the zonation of coral reef communities on reef flat and slope: a case
study for the back reef site, Ishigaki Island, southwest Japan, Coral
Reefs, 28, 229–250, https://doi.org/10.1007/s00338-008-0454-8, 2009.
Nellemann, C., Corcoran, E., Duarte, C. M., Valdés, L., De Young, C.,
Fonseca, L., and Grimsditch, G.: Blue Carbon. The Role of Healthy Oceans in
Binding Carbon. A Rapid Response Assessment 78, United Nations Environment
Programme, GRID-Arenal, 2009.
Pendleton, L., Donato, D. C., Murray, B. C., Crooks, S., Jenkins, W. A.,
Sifleet, S., Craft, C., Fourqurean, J. W., Kauffman, J. B., Marbà, N.,
Megonigal, P., Pidgeon, E., Herr, D., Gordon, D., and Baldera, A.: Estimating
global “blue carbon” emissions from conversion and degradation of
vegetated coastal ecosystems, PLOS ONE, 7, e43542, https://doi.org/10.1371/journal.pone.0043542, 2012.
Ricart, A. M., York, P. H., Rasheed, M. A., Pérez, M., Romero, J.,
Bryant, C. V., and Macreadie, P. I.: Variability of sedimentary organic
carbon in patchy seagrass landscapes, Mar. Pollut. Bull., 100, 476–482, https://doi.org/10.1016/j.marpolbul.2015.09.032, 2015.
Rozaimi, M., Fairoz, M., Hakimi, T. M., Hamdan, N. H., Omar, R., Ali, M. M.,
and Tahirin, S. A.: Carbon stores from a tropical seagrass meadow in the
midst of anthropogenic disturbance, Mar. Pollut. Bull., 119, 253–260, https://doi.org/10.1016/j.marpolbul.2017.03.073, 2017.
Samper-Villarreal, J., Lovelock, C. E., Saunders, M. I., Roelfsema, C., and
Mumby, P. J.: Organic carbon in seagrass sediments is influenced by seagrass
canopy complexity, turbidity, wave height, and water depth, Limnol.
Oceanogr., 61, 938–952, https://doi.org/10.1002/lno.10262, 2016.
Serrano, O., Lavery, P. S., Rozaimi, M., and Mateo, M. Á.: Influence of
water depth on the carbon sequestration capacity of seagrasses, Global
Biogeochem. Cy., 28, 950–961, https://doi.org/10.1002/2014GB004872, 2014.
Serrano, O., Lavery, P. S., Duarte, C. M., Kendrick, G. A., York, P. H., and
Macreadie, P. I.: Can mud (silt and clay) concentration be used to predict
soil organic carbon content within seagrass ecosystems?, Biogeosciences, 13,
4915–4926, https://doi.org/10.5194/bg-13-4915-2016, 2016a.
Serrano, O., Ricart, A. M., Lavery, P. S., Mateo, M. A., Arias-Ortiz, A.,
Masque, P., Rozaimi, M., Steven, A., and Duarte, C. M.: Key biogeochemical
factors affecting soil carbon storage in Posidonia meadows,
Biogeosciences, 13, 4581–4594, https://doi.org/10.5194/bg-13-4581-2016,
2016b.
Short, F., Carruthers, T., Dennison, W., and Waycott, M.: Global seagrass
distribution and diversity: a bioregional model, J. Exp. Mar. Biol.
Ecol., 350, 3–20, https://doi.org/10.1016/j.jembe.2007.06.012, 2007.
Suzuki, R.: Sediment production by Echinometra mathaei in the shallow
littoral zone of coral reefs, the Ishigaki island, Ryukyus, Japan, J. Geogr.,
114, 41–57, https://doi.org/10.5026/jgeography.114.41, 2005.
Tamura, H., Nadaoka, K., and Paringit, E. C.: Hydrodynamic characteristics of
a fringing coral reef on the east coast of Ishigaki Island, southwest
Japan, Coral Reefs, 26, 17–34, https://doi.org/10.1007/s00338-006-0164-z, 2007.
Tanaka, Y. and Kayanne, H.: Relationship of species composition of tropical
seagrass meadows to multiple physical environmental factors, Ecol. Res., 22,
87–96, https://doi.org/10.1007/s11284-006-0189-3, 2007.
Tanaya, T.: Contributions of the direct supply of belowground seagrass
detritus and trapping of suspended organic matter to the sedimentary organic
carbon stock in seagrass meadows, https://doi.org/10.5281/zenodo.1299640,
2018.
Terada, K., Koibuchi, Y., and Isobe, M.: Material flux in mangrove forest
based on the field observation, Proceedings of Coastal Engineering, Japan
Society of Civil Engineers, 54, 1056–1060, https://doi.org/10.2208/proce1989.54.1056,
2007 (in Japanese).
Trevathan-Tackett, S. M., Macreadie, P. I., Sanderman, J., Baldock, J.,
Howes, J. M., and Ralph, P. J.: A global assessment of the chemical
recalcitrance of seagrass tissues: implications for long-term carbon
sequestration, Front. Planet. Sci., 8, 925, https://doi.org/10.3389/fpls.2017.00925,
2017.
Versteegh, E. A. A., Gillikin, D. P., and Dehairs, F.: Analysis of δ15N values in mollusk shell organic matrix by elemental
analysis/isotope ratio mass spectrometry without acidification: an evaluation
and effects of long-term preservation, Rapid Commun. Mass Sp., 25, 675–680,
https://doi.org/10.1002/rcm.4905, 2011.
Watanabe, K. and Kuwae, T.: How organic carbon derived from multiple sources
contributes to carbon sequestration processes in a shallow coastal system?,
Glob. Change Biol., 21, 2612–2623, https://doi.org/10.1111/gcb.12924, 2015.
Yamamuro, M. and Kayanne, H.: Rapid direct determination of organic carbon
and nitrogen in carbonate-bearing sediments with a Yanaco MT-5 CHN analyzer,
Limnol. Oceanogr., 40, 1001–1005, https://doi.org/10.4319/lo.1995.40.5.1001, 1995.
Short summary
We empirically show that not only suspended-particle trapping but also the direct supply of belowground seagrass detritus can be the dominant organic carbon enrichment pathway of seagrass sediments. The relative importance of these two pathways may depend on the belowground biomass productivity. Our work identifies a previously overlooked factor controlling the carbon sink capacity of seagrass meadows and contributes to more precise estimates of global blue carbon stocks.
We empirically show that not only suspended-particle trapping but also the direct supply of...
Altmetrics
Final-revised paper
Preprint