Articles | Volume 11, issue 1
https://doi.org/10.5194/bg-11-147-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/bg-11-147-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
09 Jan 2014
Research article |
| 09 Jan 2014
Distinct bacterial-production–DOC–primary-production relationships and implications for biogenic C cycling in the South China Sea shelf
C.-C. Lai
Institute of Oceanography, National Taiwan University, Taipei, Taiwan
Y.-W. Fu
Institute of Oceanography, National Taiwan University, Taipei, Taiwan
H.-B. Liu
Division of Life Sciences, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
H.-Y. Kuo
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
K.-W. Wang
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
C.-H. Lin
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
J.-H. Tai
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
G. T. F. Wong
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
K.-Y. Lee
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
T.-Y. Chen
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
Y. Yamamoto
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
M.-F. Chow
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
Y. Kobayashi
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
C.-Y. Ko
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
F.-K. Shiah
Institute of Oceanography, National Taiwan University, Taipei, Taiwan
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
Institute of Marine Environmental Chemistry and Ecology, National Taiwan Ocean University, Keelong, Taiwan
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Zhibo Shao, Yangchun Xu, Hua Wang, Weicheng Luo, Lice Wang, Yuhong Huang, Nona Sheila R. Agawin, Ayaz Ahmed, Mar Benavides, Mikkel Bentzon-Tilia, Ilana Berman-Frank, Hugo Berthelot, Isabelle C. Biegala, Mariana B. Bif, Antonio Bode, Sophie Bonnet, Deborah A. Bronk, Mark V. Brown, Lisa Campbell, Douglas G. Capone, Edward J. Carpenter, Nicolas Cassar, Bonnie X. Chang, Dreux Chappell, Yuh-ling Lee Chen, Matthew J. Church, Francisco M. Cornejo-Castillo, Amália Maria Sacilotto Detoni, Scott C. Doney, Cecile Dupouy, Marta Estrada, Camila Fernandez, Bieito Fernández-Castro, Debany Fonseca-Batista, Rachel A. Foster, Ken Furuya, Nicole Garcia, Kanji Goto, Jesús Gago, Mary R. Gradoville, M. Robert Hamersley, Britt A. Henke, Cora Hörstmann, Amal Jayakumar, Zhibing Jiang, Shuh-Ji Kao, David M. Karl, Leila R. Kittu, Angela N. Knapp, Sanjeev Kumar, Julie LaRoche, Hongbin Liu, Jiaxing Liu, Caroline Lory, Carolin R. Löscher, Emilio Marañón, Lauren F. Messer, Matthew M. Mills, Wiebke Mohr, Pia H. Moisander, Claire Mahaffey, Robert Moore, Beatriz Mouriño-Carballido, Margaret R. Mulholland, Shin-ichiro Nakaoka, Joseph A. Needoba, Eric J. Raes, Eyal Rahav, Teodoro Ramírez-Cárdenas, Christian Furbo Reeder, Lasse Riemann, Virginie Riou, Julie C. Robidart, Vedula V. S. S. Sarma, Takuya Sato, Himanshu Saxena, Corday Selden, Justin R. Seymour, Dalin Shi, Takuhei Shiozaki, Arvind Singh, Rachel E. Sipler, Jun Sun, Koji Suzuki, Kazutaka Takahashi, Yehui Tan, Weiyi Tang, Jean-Éric Tremblay, Kendra Turk-Kubo, Zuozhu Wen, Angelicque E. White, Samuel T. Wilson, Takashi Yoshida, Jonathan P. Zehr, Run Zhang, Yao Zhang, and Ya-Wei Luo
Earth Syst. Sci. Data, 15, 3673–3709, https://doi.org/10.5194/essd-15-3673-2023, https://doi.org/10.5194/essd-15-3673-2023, 2023
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N2 fixation by marine diazotrophs is an important bioavailable N source to the global ocean. This updated global oceanic diazotroph database increases the number of in situ measurements of N2 fixation rates, diazotrophic cell abundances, and nifH gene copy abundances by 184 %, 86 %, and 809 %, respectively. Using the updated database, the global marine N2 fixation rate is estimated at 223 ± 30 Tg N yr−1, which triplicates that using the original database.
Hana Jurikova, Osamu Abe, Fuh-Kwo Shiah, and Mao-Chang Liang
Biogeosciences, 19, 2043–2058, https://doi.org/10.5194/bg-19-2043-2022, https://doi.org/10.5194/bg-19-2043-2022, 2022
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We studied the isotopic composition of oxygen dissolved in seawater in the South China Sea. This tells us about the origin of oxygen in the water column, distinguishing between biological oxygen produced by phytoplankton communities and atmospheric oxygen entering seawater through gas exchange. We found that the East Asian Monsoon plays an important role in determining the amount of oxygen produced vs. consumed by the phytoplankton, as well as in inducing vertical water mass mixing.
Yangyang Zhao, Khanittha Uthaipan, Zhongming Lu, Yan Li, Jing Liu, Hongbin Liu, Jianping Gan, Feifei Meng, and Minhan Dai
Biogeosciences, 18, 2755–2775, https://doi.org/10.5194/bg-18-2755-2021, https://doi.org/10.5194/bg-18-2755-2021, 2021
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In situ oxygen consumption rates were estimated for the first time during destruction of coastal hypoxia as disturbed by a typhoon and its reinstatement in the South China Sea off the Pearl River estuary. The reinstatement of summer hypoxia was rapid with a comparable timescale with that of its initial disturbance from frequent tropical cyclones, which has important implications for better understanding the intermittent nature of coastal hypoxia and its prediction in a changing climate.
Yanhong Lu, Shunyan Cheung, Ling Chen, Shuh-Ji Kao, Xiaomin Xia, Jianping Gan, Minhan Dai, and Hongbin Liu
Biogeosciences, 17, 6017–6032, https://doi.org/10.5194/bg-17-6017-2020, https://doi.org/10.5194/bg-17-6017-2020, 2020
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Through a comprehensive investigation, we observed differential niche partitioning among diverse ammonia-oxidizing archaea (AOA) sublineages in a typical subtropical estuary. Distinct AOA communities observed at DNA and RNA levels suggested that a strong divergence in ammonia-oxidizing activity among different AOA groups occurs. Our result highlights the importance of identifying major ammonia oxidizers at RNA level in future studies.
Juan Yao, Juying Wang, Hongbin Liu, and Kedong Yin
Biogeosciences Discuss., https://doi.org/10.5194/bg-2020-188, https://doi.org/10.5194/bg-2020-188, 2020
Preprint withdrawn
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Our study finds that winds appear to be a dominant regulating force on the formation of hypoxia in the Pearl River estuarine waters. The wind speed > 6 m/s appears to a threshold above which the water column stratification is destroyed and the formation of bottom hypoxia is interrupted. The frequency of such the above-threshold wind events decreases significantly, implying that climate change induced variability in wind speeds can exasperate the coastal formation of bottom hypoxia in the region.
Mianrun Chen, Dongyoung Kim, Hongbin Liu, and Chang-Keun Kang
Biogeosciences, 15, 2055–2073, https://doi.org/10.5194/bg-15-2055-2018, https://doi.org/10.5194/bg-15-2055-2018, 2018
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The trophic preference (i.e., food resources and trophic levels) of different copepod groups was assessed along a salinity gradient in the temperate estuarine Gwangyang Bay of Korea, based on a seasonal investigation of taxonomic results in 2015 and stable isotope analysis incorporating multiple linear regression models. Our results depict a simple energy flow of the planktonic food web of Gwangyang Bay.
Chung-Chi Chen, Gwo-Ching Gong, Wen-Chen Chou, Chih-Ching Chung, Chih-Hao Hsieh, Fuh-Kwo Shiah, and Kuo-Ping Chiang
Biogeosciences, 14, 2597–2609, https://doi.org/10.5194/bg-14-2597-2017, https://doi.org/10.5194/bg-14-2597-2017, 2017
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To understand the flooding effects on a pelagic ecosystem in the East China Sea (ECS), a variety of variables were measured in 2009 (non-flood) and 2010 (flood). In 2010, the organic carbon consumption was higher than in 2009; this could be attributed to the vigorous plankton activities observed in low-salinity areas. A huge amount of f CO2 was also drawn down in the flood. This flood effect might become more pronounced as extreme rainfall events increase dramatically throughout the world.
Hana Jurikova, Tania Guha, Osamu Abe, Fuh-Kwo Shiah, Chung-Ho Wang, and Mao-Chang Liang
Biogeosciences, 13, 6683–6698, https://doi.org/10.5194/bg-13-6683-2016, https://doi.org/10.5194/bg-13-6683-2016, 2016
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Life on Earth is directly or indirectly linked to primary production (PP), the quantification of which poses a challenge. In our study we use the oxygen isotopes and oxygen–argon ratios technique to estimate PP in situ. To date this method has been used to assess PP in the ocean and we expand on its application to freshwater systems. Providing that the physical structure of the water column is constrained, this method presents a powerful tracer for atmospheric vs. photosynthetic oxygen input.
Hongbin Liu and Chih-Jung Wu
Biogeosciences, 13, 4767–4775, https://doi.org/10.5194/bg-13-4767-2016, https://doi.org/10.5194/bg-13-4767-2016, 2016
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The transport of organic C from the surface to the deep ocean by sinking particles composed of remains of dead cells and zooplankton fecal pellets can reduce the atmospheric CO2. Study of the effect of the silica content of diatoms, one of the most important primary products, on the production, degradation and sinking of its fecal pellets provides a better understanding of the complexity and variability of the planktonic food web and its implication on the vertical flux of C in the global ocean.
Jr-Chuan Huang, Tsung-Yu Lee, Teng-Chiu Lin, Thomas Hein, Li-Chin Lee, Yu-Ting Shih, Shuh-Ji Kao, Fuh-Kwo Shiah, and Neng-Huei Lin
Biogeosciences, 13, 1787–1800, https://doi.org/10.5194/bg-13-1787-2016, https://doi.org/10.5194/bg-13-1787-2016, 2016
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The mean riverine DIN export of 49 watersheds in Taiwan is ∼ 3800 kg N km−2 yr−1, 18 times the global average. The mean riverine DIN export ratio is 0.30–0.51, which is much higher than the average of 0.20–0.25 of large rivers around the world, indicating excessive N input relative to ecosystem retention capacity. The DIN export ratio is positively related to agriculture input, and levels of human disturbance and watersheds with high DIN export ratios are likely at advanced stages of N excess.
H. Jing, E. Rocke, L. Kong, X. Xia, H. Liu, and M. R. Landry
Biogeosciences Discuss., https://doi.org/10.5194/bgd-12-13483-2015, https://doi.org/10.5194/bgd-12-13483-2015, 2015
Manuscript not accepted for further review
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Photosynthetic Dinoflagellates predominated in the surface, while potential parasitic Dinoflagellates and Ciliates dominated in the OMZ and deeper water in Costa Rica Dome. Total and active protists in the anoxic core were distinct from those in others depths. Reduced community diversity and presence of parasitic/symbiotic trophic lifestyles in the suboxic/anoxic OMZ suggests that oxygen deficiency could cause a change of protist community and the associated microbial food web as well.
C.-C. Chen, G.-C. Gong, W.-C. Chou, C.-C. Chung, F.-K. Shiah, and K.-P. Chiang
Biogeosciences Discuss., https://doi.org/10.5194/bgd-12-5609-2015, https://doi.org/10.5194/bgd-12-5609-2015, 2015
Revised manuscript not accepted
K.-K. Liu, C.-K. Kang, T. Kobari, H. Liu, C. Rabouille, and K. Fennel
Biogeosciences, 11, 7061–7075, https://doi.org/10.5194/bg-11-7061-2014, https://doi.org/10.5194/bg-11-7061-2014, 2014
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This paper provides background info on the East China Sea, Japan/East Sea and South China Sea and highlights major findings in the special issue on their biogeochemical conditions and ecosystem functions. The three seas are subject to strong impacts from human activities and/or climate forcing. Because these continental margins sustain arguably some of the most productive marine ecosystems in the world, changes in these stressed ecosystems may threaten the livelihood of a large human population.
T.-Y. Lee, Y.-T. Shih, J.-C. Huang, S.-J. Kao, F.-K. Shiah, and K.-K. Liu
Biogeosciences, 11, 5307–5321, https://doi.org/10.5194/bg-11-5307-2014, https://doi.org/10.5194/bg-11-5307-2014, 2014
S.-C. Hsu, G.-C. Gong, F.-K. Shiah, C.-C. Hung, S.-J. Kao, R. Zhang, W.-N. Chen, C.-C. Chen, C. C.-K. Chou, Y.-C. Lin, F.-J. Lin, and S.-H. Lin
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acpd-14-21433-2014, https://doi.org/10.5194/acpd-14-21433-2014, 2014
Revised manuscript has not been submitted
K. Suzuki, A. Hattori-Saito, Y. Sekiguchi, J. Nishioka, M. Shigemitsu, T. Isada, H. Liu, and R. M. L. McKay
Biogeosciences, 11, 2503–2517, https://doi.org/10.5194/bg-11-2503-2014, https://doi.org/10.5194/bg-11-2503-2014, 2014
C. Guo, H. Liu, L. Zheng, S. Song, B. Chen, and B. Huang
Biogeosciences, 11, 1847–1862, https://doi.org/10.5194/bg-11-1847-2014, https://doi.org/10.5194/bg-11-1847-2014, 2014
C.-C. Chen, G.-C. Gong, F.-K. Shiah, W.-C. Chou, and C.-C. Hung
Biogeosciences, 10, 2931–2943, https://doi.org/10.5194/bg-10-2931-2013, https://doi.org/10.5194/bg-10-2931-2013, 2013
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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)
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
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
Quantification and mitigation of bottom trawling impacts on sedimentary organic carbon stocks in the North Sea
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
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Ocean alkalinity enhancement using sodium carbonate salts does not impact Fe dynamics in a mesocosm experiment
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
Picoplanktonic methane production in eutrophic surface waters
Influence of Ocean Alkalinity Enhancement with Olivine or Steel Slag on a Coastal Plankton Community in Tasmania
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
Intra-scenario variability of trends and controls of near-bed oxygen concentration on the Northwest European Continental Shelf under climate change
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
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Temporal and spatial evolution of bottom-water hypoxia in the St Lawrence estuarine system
Significant nutrient consumption in the dark subsurface layer during a diatom bloom: a case study on Funka Bay, Hokkaido, Japan
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Limits and CO2 equilibration of near-coast alkalinity enhancement
Role of phosphorus in the seasonal deoxygenation of the East China Sea shelf
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Observed and projected global warming pressure on coastal hypoxia
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Interannual variabilities, long-term trends, and regulating factors of low-oxygen conditions in the coastal waters off Hong Kong
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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
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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
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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.
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
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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.
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
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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
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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
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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
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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
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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
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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
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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
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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.
Lucas Porz, Wenyan Zhang, Nils Gerrit Christiansen, Jan Kossack, Ute Daewel, and Corinna Schrum
EGUsphere, https://doi.org/10.5194/egusphere-2024-399, https://doi.org/10.5194/egusphere-2024-399, 2024
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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.
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
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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
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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
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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
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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
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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.
David González-Santana, María Segovia, Melchor González-Dávila, Librada Ramírez, Aridane G. González, Leonardo J. Pozzo, Veronica Arnone, Victor Vázquez, Ulf Riebesell, and J. Magdalena Santana-Casiano
EGUsphere, https://doi.org/10.5194/egusphere-2023-2868, https://doi.org/10.5194/egusphere-2023-2868, 2023
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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.
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
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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
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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.
Sandy E. Tenorio and Laura Farías
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-185, https://doi.org/10.5194/bg-2023-185, 2023
Revised manuscript accepted for BG
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Time series studies show that CH4 is highly dynamic on the coastal ocean surface and that planktonic communities are linked to CH4 accumulation as is found in coastal upwelling off Central Chile. We’ve identified the crucial role of picoplankton (>3μm) in CH4 recycling, especially with the addition of methylated substrates (TMA and MPn) during upwelling and non-upwelling periods. These insights improve understanding of surface ocean CH4 recycling, aiding accurate CH4 emissions estimates.
Jiaying A. Guo, Robert F. Strzepek, Kerrie M. Swadling, Ashley T. Townsend, and Lennart T. Bach
EGUsphere, https://doi.org/10.5194/egusphere-2023-2120, https://doi.org/10.5194/egusphere-2023-2120, 2023
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Ocean alkalinity enhancement (OAE) aims to increase atmospheric CO2 sequestration in the oceans by spreading ground alkaline materials into the ocean. To assess the environmental impacts of OAE, we used 53 L microcosms to test how coastal plankton communities respond to OAE with olivine or steel slag as alkalinity sources. Overall, steel slag is much more efficient for CO2 removal than olivine and appears to be induce less changes in the phytoplankton and zooplankton communities.
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
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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
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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
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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
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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.
Giovanni Galli, Sarah Wakelin, James Harle, Jason Holt, and Yuri Artioli
EGUsphere, https://doi.org/10.5194/egusphere-2023-1049, https://doi.org/10.5194/egusphere-2023-1049, 2023
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In this work we looked at the projected change in bottom water oxygen content in an ensemble of ocean climate change models of the North Western European Shelf. What emerged is that, 1. oxygen decreases in all models, 2. in the models with the most warming, a change in circulation patterns is tied to the emergence of low oxygen hotspots in the Eastern North Sea, and, 3. in relatively shallow coastal areas increasing in primary production partially mitigates oxygen decline.
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
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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
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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
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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
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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
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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
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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.
Sachi Umezawa, Manami Tozawa, Yuichi Nosaka, Daiki Nomura, Hiroji Onishi, Hiroto Abe, Tetsuya Takatsu, and Atsushi Ooki
Biogeosciences, 20, 421–438, https://doi.org/10.5194/bg-20-421-2023, https://doi.org/10.5194/bg-20-421-2023, 2023
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We conducted repetitive observations in Funka Bay, Japan, during the spring bloom 2019. We found nutrient concentration decreases in the dark subsurface layer during the bloom. Incubation experiments confirmed that diatoms could consume nutrients at a substantial rate, even in darkness. We concluded that the nutrient reduction was mainly caused by nutrient consumption by diatoms in the dark.
Dirk Jong, Lisa Bröder, Tommaso Tesi, Kirsi H. Keskitalo, Nikita Zimov, Anna Davydova, Philip Pika, Negar Haghipour, Timothy I. Eglinton, and Jorien E. Vonk
Biogeosciences, 20, 271–294, https://doi.org/10.5194/bg-20-271-2023, https://doi.org/10.5194/bg-20-271-2023, 2023
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With this study, we want to highlight the importance of studying both land and ocean together, and water and sediment together, as these systems function as a continuum, and determine how organic carbon derived from permafrost is broken down and its effect on global warming. Although on the one hand it appears that organic carbon is removed from sediments along the pathway of transport from river to ocean, it also appears to remain relatively ‘fresh’, despite this removal and its very old age.
Georgia Filippi, Manos Dassenakis, Vasiliki Paraskevopoulou, and Konstantinos Lazogiannis
Biogeosciences, 20, 163–189, https://doi.org/10.5194/bg-20-163-2023, https://doi.org/10.5194/bg-20-163-2023, 2023
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The pollution of the western Saronikos Gulf from heavy metals has been examined through the study of marine sediment cores. It is a deep gulf (maximum depth 440 m) near Athens affected by industrial and volcanic activity. Eight cores were received from various stations and depths and analysed for their heavy metal content and geochemical characteristics. The results were evaluated by using statistical methods, environmental indicators and comparisons with old data.
Jing He and Michael D. Tyka
Biogeosciences, 20, 27–43, https://doi.org/10.5194/bg-20-27-2023, https://doi.org/10.5194/bg-20-27-2023, 2023
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Recently, ocean alkalinity enhancement (OAE) has gained interest as a scalable way to address the urgent need for negative CO2 emissions. In this paper we examine the capacity of different coastlines to tolerate alkalinity enhancement and the time scale of CO2 uptake following the addition of a given quantity of alkalinity. The results suggest that OAE has significant potential and identify specific favorable and unfavorable coastlines for its deployment.
Arnaud Laurent, Haiyan Zhang, and Katja Fennel
Biogeosciences, 19, 5893–5910, https://doi.org/10.5194/bg-19-5893-2022, https://doi.org/10.5194/bg-19-5893-2022, 2022
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The Changjiang is the main terrestrial source of nutrients to the East China Sea (ECS). Nutrient delivery to the ECS has been increasing since the 1960s, resulting in low oxygen (hypoxia) during phytoplankton decomposition in summer. River phosphorus (P) has increased less than nitrogen, and therefore, despite the large nutrient delivery, phytoplankton growth can be limited by the lack of P. Here, we investigate this link between P limitation, phytoplankton production/decomposition, and hypoxia.
Coline Poppeschi, Guillaume Charria, Anne Daniel, Romaric Verney, Peggy Rimmelin-Maury, Michaël Retho, Eric Goberville, Emilie Grossteffan, and Martin Plus
Biogeosciences, 19, 5667–5687, https://doi.org/10.5194/bg-19-5667-2022, https://doi.org/10.5194/bg-19-5667-2022, 2022
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This paper aims to understand interannual changes in the initiation of the phytoplankton growing period (IPGP) in the current context of global climate changes over the last 20 years. An important variability in the timing of the IPGP is observed with a trend towards a later IPGP during this last decade. The role and the impact of extreme events (cold spells, floods, and wind burst) on the IPGP is also detailed.
Lin Yang, Jing Zhang, Anja Engel, and Gui-Peng Yang
Biogeosciences, 19, 5251–5268, https://doi.org/10.5194/bg-19-5251-2022, https://doi.org/10.5194/bg-19-5251-2022, 2022
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Enrichment factors of dissolved organic matter (DOM) in the eastern marginal seas of China exhibited a significant spatio-temporal variation. Photochemical and enrichment processes co-regulated DOM enrichment in the sea-surface microlayer (SML). Autochthonous DOM was more frequently enriched in the SML than terrestrial DOM. DOM in the sub-surface water exhibited higher aromaticity than that in the SML.
Mona Norbisrath, Johannes Pätsch, Kirstin Dähnke, Tina Sanders, Gesa Schulz, Justus E. E. van Beusekom, and Helmuth Thomas
Biogeosciences, 19, 5151–5165, https://doi.org/10.5194/bg-19-5151-2022, https://doi.org/10.5194/bg-19-5151-2022, 2022
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Total alkalinity (TA) regulates the oceanic storage capacity of atmospheric CO2. TA is also metabolically generated in estuaries and influences coastal carbon storage through its inflows. We used water samples and identified the Hamburg port area as the one with highest TA generation. Of the overall riverine TA load, 14 % is generated within the estuary. Using a biogeochemical model, we estimated potential effects on the coastal carbon storage under possible anthropogenic and climate changes.
Le Zhang and Z. George Xue
Biogeosciences, 19, 4589–4618, https://doi.org/10.5194/bg-19-4589-2022, https://doi.org/10.5194/bg-19-4589-2022, 2022
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We adopt a high-resolution carbon model for the Gulf of Mexico (GoM) and calculate the decadal trends of important carbon system variables in the GoM from 2001 to 2019. The GoM surface CO2 values experienced a steady increase over the past 2 decades, and the ocean surface pH is declining. Although carbonate saturation rates remain supersaturated with aragonite, they show a slightly decreasing trend. The northern GoM is a stronger carbon sink than we thought.
Michael M. Whitney
Biogeosciences, 19, 4479–4497, https://doi.org/10.5194/bg-19-4479-2022, https://doi.org/10.5194/bg-19-4479-2022, 2022
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Coastal hypoxia is a major environmental problem of increasing severity. The 21st-century projections analyzed indicate global coastal waters will warm and experience rapid declines in oxygen. The forecasted median coastal trends for increasing sea surface temperature and decreasing oxygen capacity are 48 % and 18 % faster than the rates observed over the last 4 decades. Existing hypoxic areas are expected to worsen, and new hypoxic areas likely will emerge under these warming-related pressures.
Bryce Van Dam, Nele Lehmann, Mary A. Zeller, Andreas Neumann, Daniel Pröfrock, Marko Lipka, Helmuth Thomas, and Michael Ernst Böttcher
Biogeosciences, 19, 3775–3789, https://doi.org/10.5194/bg-19-3775-2022, https://doi.org/10.5194/bg-19-3775-2022, 2022
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We quantified sediment–water exchange at shallow sites in the North and Baltic seas. We found that porewater irrigation rates in the former were approximately twice as high as previously estimated, likely driven by relatively high bioirrigative activity. In contrast, we found small net fluxes of alkalinity, ranging from −35 µmol m−2 h−1 (uptake) to 53 µmol m−2 h−1 (release). We attribute this to low net denitrification, carbonate mineral (re-)precipitation, and sulfide (re-)oxidation.
Jiaying Abby Guo, Robert Strzepek, Anusuya Willis, Aaron Ferderer, and Lennart Thomas Bach
Biogeosciences, 19, 3683–3697, https://doi.org/10.5194/bg-19-3683-2022, https://doi.org/10.5194/bg-19-3683-2022, 2022
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Ocean alkalinity enhancement is a CO2 removal method with significant potential, but it can lead to a perturbation of the ocean with trace metals such as nickel. This study tested the effect of increasing nickel concentrations on phytoplankton growth and photosynthesis. We found that the response to nickel varied across the 11 phytoplankton species tested here, but the majority were rather insensitive. We note, however, that responses may be different under other experimental conditions.
Malcolm E. Scully, W. Rockwell Geyer, David Borkman, Tracy L. Pugh, Amy Costa, and Owen C. Nichols
Biogeosciences, 19, 3523–3536, https://doi.org/10.5194/bg-19-3523-2022, https://doi.org/10.5194/bg-19-3523-2022, 2022
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For two consecutive summers, the bottom waters in southern Cape Cod Bay became severely depleted of dissolved oxygen. Low oxygen levels in bottom waters have never been reported in this area before, and this unprecedented occurrence is likely the result of a new algae species that recently began blooming during the late-summer months. We present data suggesting that blooms of this new species are the result of regional climate change including warmer waters and changes in summer winds.
Zheng Chen, Bin Wang, Chuang Xu, Zhongren Zhang, Shiyu Li, and Jiatang Hu
Biogeosciences, 19, 3469–3490, https://doi.org/10.5194/bg-19-3469-2022, https://doi.org/10.5194/bg-19-3469-2022, 2022
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Deterioration of low-oxygen conditions in the coastal waters off Hong Kong was revealed by monitoring data over two decades. The declining wind forcing and the increasing nutrient input contributed significantly to the areal expansion and intense deterioration of low-oxygen conditions. Also, the exacerbated eutrophication drove a shift in the dominant source of organic matter from terrestrial inputs to in situ primary production, which has probably led to an earlier onset of hypoxia in summer.
Stella-Theresa Stoicescu, Jaan Laanemets, Taavi Liblik, Māris Skudra, Oliver Samlas, Inga Lips, and Urmas Lips
Biogeosciences, 19, 2903–2920, https://doi.org/10.5194/bg-19-2903-2022, https://doi.org/10.5194/bg-19-2903-2022, 2022
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Coastal basins with high input of nutrients often suffer from oxygen deficiency. In summer 2018, the extent of oxygen depletion was exceptional in the Gulf of Riga. We analyzed observational data and found that extensive oxygen deficiency appeared since the water layer close to the seabed, where oxygen is consumed, was separated from the surface layer. The problem worsens if similar conditions restricting vertical transport of oxygen occur more frequently in the future.
Justin C. Tiano, Jochen Depestele, Gert Van Hoey, João Fernandes, Pieter van Rijswijk, and Karline Soetaert
Biogeosciences, 19, 2583–2598, https://doi.org/10.5194/bg-19-2583-2022, https://doi.org/10.5194/bg-19-2583-2022, 2022
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This study gives an assessment of bottom trawling on physical, chemical, and biological characteristics in a location known for its strong currents and variable habitats. Although trawl gears only removed the top 1 cm of the seabed surface, impacts on reef-building tubeworms significantly decreased carbon and nutrient cycling. Lighter trawls slightly reduced the impact on fauna and nutrients. Tubeworms were strongly linked to biogeochemical and faunal aspects before but not after trawling.
Inda Brinkmann, Christine Barras, Tom Jilbert, Tomas Næraa, K. Mareike Paul, Magali Schweizer, and Helena L. Filipsson
Biogeosciences, 19, 2523–2535, https://doi.org/10.5194/bg-19-2523-2022, https://doi.org/10.5194/bg-19-2523-2022, 2022
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The concentration of the trace metal barium (Ba) in coastal seawater is a function of continental input, such as riverine discharge. Our geochemical records of the severely hot and dry year 2018, and following wet year 2019, reveal that prolonged drought imprints with exceptionally low Ba concentrations in benthic foraminiferal calcium carbonates of coastal sediments. This highlights the potential of benthic Ba / Ca to trace past climate extremes and variability in coastal marine records.
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