Articles | Volume 19, issue 11
https://doi.org/10.5194/bg-19-2903-2022
© Author(s) 2022. 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-19-2903-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
14 Jun 2022
Research article |
| 14 Jun 2022
| 14 Jun 2022
Causes of the extensive hypoxia in the Gulf of Riga in 2018
Stella-Theresa Stoicescu
CORRESPONDING AUTHOR
Department of Marine Systems, Tallinn University of Technology, Tallinn, 19086, Estonia
Jaan Laanemets
Department of Marine Systems, Tallinn University of Technology, Tallinn, 19086, Estonia
Taavi Liblik
Department of Marine Systems, Tallinn University of Technology, Tallinn, 19086, Estonia
Māris Skudra
Latvian Institute of Aquatic Ecology, Riga, 1007, Latvia
Oliver Samlas
Department of Marine Systems, Tallinn University of Technology, Tallinn, 19086, Estonia
Inga Lips
Department of Marine Systems, Tallinn University of Technology, Tallinn, 19086, Estonia
EuroGOOS AISBL, Brussels, 1000, Belgium
Urmas Lips
Department of Marine Systems, Tallinn University of Technology, Tallinn, 19086, Estonia
Related authors
Silvie Lainela, Erik Jacobs, Stella-Theresa Stoicescu, Gregor Rehder, and Urmas Lips
EGUsphere, https://doi.org/10.5194/egusphere-2024-598, https://doi.org/10.5194/egusphere-2024-598, 2024
Short summary
Short summary
We evaluate the variability of carbon dioxide and methane in the surface layer of the north-eastern basins of the Baltic Sea in 2018. We show that the shallower coastal areas have considerably higher spatial variability and seasonal amplitude of surface layer pCO2 and cCH4 than measured in the Baltic Sea offshore areas. Despite this high variability, caused mostly by coastal physical processes, the average annual air-sea CO2 fluxes differed only marginally between the sub-basins.
Silvie Lainela, Erik Jacobs, Stella-Theresa Stoicescu, Gregor Rehder, and Urmas Lips
EGUsphere, https://doi.org/10.5194/egusphere-2024-598, https://doi.org/10.5194/egusphere-2024-598, 2024
Short summary
Short summary
We evaluate the variability of carbon dioxide and methane in the surface layer of the north-eastern basins of the Baltic Sea in 2018. We show that the shallower coastal areas have considerably higher spatial variability and seasonal amplitude of surface layer pCO2 and cCH4 than measured in the Baltic Sea offshore areas. Despite this high variability, caused mostly by coastal physical processes, the average annual air-sea CO2 fluxes differed only marginally between the sub-basins.
Taavi Liblik, Germo Väli, Kai Salm, Jaan Laanemets, Madis-Jaak Lilover, and Urmas Lips
Ocean Sci., 18, 857–879, https://doi.org/10.5194/os-18-857-2022, https://doi.org/10.5194/os-18-857-2022, 2022
Short summary
Short summary
An extensive measurement campaign and numerical simulations were conducted in the central Baltic Sea. The persistent circulation patterns were detected in steady weather conditions. The patterns included various circulation features. A coastal boundary current was observed along the eastern coast. The deep layer current towards the north was detected as well. This current is an important deeper limb of the overturning circulation of the Baltic Sea. The circulation regime has an annual cycle.
Andreas Lehmann, Kai Myrberg, Piia Post, Irina Chubarenko, Inga Dailidiene, Hans-Harald Hinrichsen, Karin Hüssy, Taavi Liblik, H. E. Markus Meier, Urmas Lips, and Tatiana Bukanova
Earth Syst. Dynam., 13, 373–392, https://doi.org/10.5194/esd-13-373-2022, https://doi.org/10.5194/esd-13-373-2022, 2022
Short summary
Short summary
The salinity in the Baltic Sea is not only an important topic for physical oceanography as such, but it also integrates the complete water and energy cycle. It is a primary external driver controlling ecosystem dynamics of the Baltic Sea. The long-term dynamics are controlled by river runoff, net precipitation, and the water mass exchange between the North Sea and Baltic Sea. On shorter timescales, the ephemeral atmospheric conditions drive a very complex and highly variable salinity regime.
Taavi Liblik, Germo Väli, Inga Lips, Madis-Jaak Lilover, Villu Kikas, and Jaan Laanemets
Ocean Sci., 16, 1475–1490, https://doi.org/10.5194/os-16-1475-2020, https://doi.org/10.5194/os-16-1475-2020, 2020
Short summary
Short summary
The upper mixed layer, shallower than the depth of the euphotic zone, is one of the preconditions for enhanced primary production in the ocean. In the Baltic Sea, the general understanding is that the upper mixed layer is much deeper in winter. In this study, we demonstrate that wintertime shallow stratification and an elevated phytoplankton biomass proxy, chlorophyll, are common in the Gulf of Finland. Stratification is invoked by the westward flow of riverine water forced by an easterly wind.
Taavi Liblik, Yijing Wu, Daidu Fan, and Dinghui Shang
Biogeosciences, 17, 2875–2895, https://doi.org/10.5194/bg-17-2875-2020, https://doi.org/10.5194/bg-17-2875-2020, 2020
Short summary
Short summary
Multiple factors have been accused of triggering coastal hypoxia off the Changjiang Estuary. In situ observations, remote sensing and numerical simulation data were used to study dissolved oxygen depletion in the area. Oxygen distributions can be explained by wind forcing and river discharge, as well as concurrent features in surface and deep layer circulation. If summer monsoon prevails, hypoxia more likely occurs in the north while hypoxia in the south appears if the summer monsoon is weaker.
Jun She, Icarus Allen, Erik Buch, Alessandro Crise, Johnny A. Johannessen, Pierre-Yves Le Traon, Urmas Lips, Glenn Nolan, Nadia Pinardi, Jan H. Reißmann, John Siddorn, Emil Stanev, and Henning Wehde
Ocean Sci., 12, 953–976, https://doi.org/10.5194/os-12-953-2016, https://doi.org/10.5194/os-12-953-2016, 2016
Short summary
Short summary
This white paper addresses key scientific challenges and research priorities for the development of operational oceanography in Europe for the next 5–10 years. Knowledge gaps and deficiencies are identified in relation to common scientific challenges in four EuroGOOS knowledge areas: European ocean observations, modelling and forecasting technology, coastal operational oceanography, and operational ecology.
Villu Kikas and Urmas Lips
Ocean Sci., 12, 843–859, https://doi.org/10.5194/os-12-843-2016, https://doi.org/10.5194/os-12-843-2016, 2016
Urmas Lips, Villu Kikas, Taavi Liblik, and Inga Lips
Ocean Sci., 12, 715–732, https://doi.org/10.5194/os-12-715-2016, https://doi.org/10.5194/os-12-715-2016, 2016
Short summary
Short summary
Multi-platform high-resolution observations in the Gulf of Finland in the summers of 2009–2012 revealed pronounced variability at the sub-mesoscale in the presence of mesoscale features, such as upwelling/downwelling events, fronts, and eddies. The analysis suggests that the sub-mesoscale processes could contribute considerably to the downscale energy cascade and play a major role in phytoplankton growth enhancement via vertical transport and re-stratification of the surface layer.
Related subject area
Biogeochemistry: Coastal Ocean
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
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
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
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
Hypoxia also occurs in small highly turbid estuaries: the example of the Charente (Bay of Biscay)
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
Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea
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
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
Significant nutrient consumption in the dark subsurface layer during a diatom bloom: a case study on Funka Bay, Hokkaido, Japan
Contrasts in dissolved, particulate, and sedimentary organic carbon from the Kolyma River to the East Siberian Shelf
Sediment quality assessment in an industrialized Greek coastal marine area (western Saronikos Gulf)
Limits and CO2 equilibration of near-coast alkalinity enhancement
Role of phosphorus in the seasonal deoxygenation of the East China Sea shelf
Interannual variability of the initiation of the phytoplankton growing period in two French coastal ecosystems
Spatio-temporal distribution, photoreactivity and environmental control of dissolved organic matter in the sea-surface microlayer of the eastern marginal seas of China
Metabolic alkalinity release from large port facilities (Hamburg, Germany) and impact on coastal carbon storage
A Numerical reassessment of the Gulf of Mexico carbon system in connection with the Mississippi River and global ocean
Observed and projected global warming pressure on coastal hypoxia
Benthic alkalinity fluxes from coastal sediments of the Baltic and North seas: comparing approaches and identifying knowledge gaps
Investigating the effect of nickel concentration on phytoplankton growth to assess potential side-effects of ocean alkalinity enhancement
Unprecedented summer hypoxia in southern Cape Cod Bay: an ecological response to regional climate change?
Interannual variabilities, long-term trends, and regulating factors of low-oxygen conditions in the coastal waters off Hong Kong
Trawling effects on biogeochemical processes are mediated by fauna in high-energy biogenic-reef-inhabited coastal sediments
Drought recorded by Ba∕Ca in coastal benthic foraminifera
A nitrate budget of the Bohai Sea based on an isotope mass balance model
Suspended particulate matter drives the spatial segregation of nitrogen turnover along the hyper-turbid Ems estuary
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.
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
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.
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.
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
Short summary
Short summary
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.
Simone R. Alin, Jan A. Newton, Richard A. Feely, Samantha A. Siedlecki, and Dana J. Greeley
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-181, https://doi.org/10.5194/bg-2023-181, 2023
Revised manuscript accepted for BG
Short summary
Short summary
We provide a new multi-stressor data product allowed us to characterize the seasonality of temperature, oxygen, and carbon dioxide in the southern Salish Sea and provided insight into impacts of major marine heatwave and precipitation anomalies on regional ocean acidification and hypoxia. We also described the present-day frequencies of temperature, oxygen, and ocean acidification conditions that cross thresholds of sensitive regional species that are economically or ecologically important.
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
Short summary
Short summary
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
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.
Sabine Schmidt and Ibrahima I. Diallo
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-150, https://doi.org/10.5194/bg-2023-150, 2023
Revised manuscript accepted for BG
Short summary
Short summary
Along the French coast facing the Bay of Biscay, the two main estuaries, the Gironde and the Loire, experience hypoxia, motivating this study of the small Charente estuary between them. This work highlights a minimum oxygen zone in the Charente estuary extending for about 25 km, temperature being the main factor controlling the hypoxia. This calls for the monitoring of small highly turbid macrotidal estuaries vulnerable to hypoxia, a risk that will increase with global warming.
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.
Charlotte Williams, Tom Hull, Matthew Palmer, Claire Mahaffey, Naomi Greenwood, Jan Kaiser, and Matthew Toberman
Biogeosciences Discuss., https://doi.org/10.5194/bg-2023-100, https://doi.org/10.5194/bg-2023-100, 2023
Revised manuscript accepted for BG
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 reach ecologically low levels.
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
Short summary
Short summary
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
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.
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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
Short summary
Short summary
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.
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
Short summary
Short summary
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
Short summary
Short summary
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.
Shichao Tian, Birgit Gaye, Jianhui Tang, Yongming Luo, Wenguo Li, Niko Lahajnar, Kirstin Dähnke, Tina Sanders, Tianqi Xiong, Weidong Zhai, and Kay-Christian Emeis
Biogeosciences, 19, 2397–2415, https://doi.org/10.5194/bg-19-2397-2022, https://doi.org/10.5194/bg-19-2397-2022, 2022
Short summary
Short summary
We constrain the nitrogen budget and in particular the internal sources and sinks of nitrate in the Bohai Sea by using a mass-based and dual stable isotope approach based on δ15N and δ18O of nitrate. Based on available mass fluxes and isotope data an updated nitrogen budget is proposed. Compared to previous estimates, it is more complete and includes the impact of the interior cycle (nitrification) on the nitrate pool. The main external nitrogen sources are rivers contributing 19.2 %–25.6 %.
Gesa Schulz, Tina Sanders, Justus E. E. van Beusekom, Yoana G. Voynova, Andreas Schöl, and Kirstin Dähnke
Biogeosciences, 19, 2007–2024, https://doi.org/10.5194/bg-19-2007-2022, https://doi.org/10.5194/bg-19-2007-2022, 2022
Short summary
Short summary
Estuaries can significantly alter nutrient loads before reaching coastal waters. Our study of the heavily managed Ems estuary (Northern Germany) reveals three zones of nitrogen turnover along the estuary with water-column denitrification in the most upstream hyper-turbid part, nitrate production in the middle reaches and mixing/nitrate uptake in the North Sea. Suspended particulate matter was the overarching control on nitrogen cycling in the hyper-turbid estuary.
Cited articles
Aigars, J. and Carman, R.:
Seasonal and spatial variations of carbon and nitrogen distribution in the surface sediments of the Gulf of Riga, Baltic Sea, Chemosphere, 43, 313–320, 2001.
Aigars, J., Poikāne, R., Dalsgaard, T., Eglīte, E., and Jansons, M.:
Biogeochemistry of N, P and SI in the Gulf of Riga surface sediments: Implications of seasonally changing factors, Cont. Shelf Res., 105, 112–120, 2015.
Astok, V., Otsmann, M., and Suursaar, Ü.:
Water exchange as the main physical process in semi-enclosed marine systems: the Gulf of Riga case, Hydrobiologia, 393, 11–18, https://doi.org/10.1023/A:1003517110726, 1999.
Berzinsh, V.:
Hydrology, in: Ecosystem of the Gulf of Riga between 1920–1990, edited by: Ojaveer, E., Estonian Academy Publishers, Tallinn, 7–31, ISBN 9985-50-065-2, 1995.
Bindoff, N. L., Cheung, W. W. L., Kairo, J. G., Arístegui, J., Guinder, V. A., Hallberg, R., Hilmi, N., Jiao, N., Karim, M. S., Levin, L., O'Donoghue, S., Cuicapusa, S. R. P., Rinkevich, B., Suga, T., Tagliabue, A., and Williamson, P.:
Changing Ocean, Marine Ecosystems, and Dependent Communities, in: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate, edited by: Pörtner, H.-O., Roberts, D. C., Masson-Delmotte, V., Zhai, P., Tignor, M., Poloczanska, E., Mintenbeck, K., Alegría, A., Nicolai, M., Okem, A., Petzold, J., Rama, B., and Weyer, N. M., Cambridge University Press, Cambridge, UK and New York, NY, USA, 447–587, https://doi.org/10.1017/9781009157964.007, 2019.
Bonsdorff, E., Diaz, R. J., Rosenberg, R., Norkko, A., and Cutter Jr, G. R.:
Characterization of soft-bottom benthic habitats of the Åland Islands, norther Baltic Sea, Mar. Ecol.-Prog. Ser., 142, 235–245, 1996.
Boynton, W. R., Ceballos, M. A. C., Bailey, E. M., Hodgkins, C. L. S., Humphrey, J. L., and Testa, J. M.:
Oxygen and Nutrient Exchanges at the Sediment-Water Interface: a Global Synthesis and Critique of Estuarine and Coastal Data, Estuar. Coast., 41, 301–333, https://doi.org/10.1007/s12237-017-0275-5, 2018.
Caballero-Alfonso, A. M., Carstensen, J., and Conley, D. J.:
Biogeochemical and environmental drivers of coastal hypoxia, J. Marine Syst., 141, 190–199, 2015.
Carstensen, J. and Conley, D. J.:
Baltic Sea Hypoxia Takes Many Shapes and Sizes, Limnol. Oceanogr. Bull., 28, 125–129, https://doi.org/10.1002/lob.10350, 2019.
Carstensen, J., Andersen, J. H., Gustafsson, B. G., and Conley, D. J.:
Deoxygenation of the Baltic Sea during the last century, P. Natl. Acad. Sci. USA, 111, 5628–5633, 2014.
Christensen, O. B., Kjellström, E., and Zorita, E.:
in Second Assessment of Climate Change for the Baltic Sea Basin, in: Second Assessment of Climate Change for the Baltic Sea Basin, edited by: BACC II Author Team, Springer International Publishing, 217–233, https://doi.org/10.1007/978-3-319-16006-1_11, 2015.
Codiga, D. L., Stoffel, H. E., Decautis, C. F., Kiernan, S., and Oviatt, C. A.:
Narragansett Bay Hypoxic Event Characteristics Based on Fixed-Site Monitoring Network Time Series: Intermittency, Geographic Distribution, Spatial Synchronicity, and Interannual Variability, Estuar. Coast., 32, 621–641, https://doi.org/10.1007/s12237-009-9165-9, 2009.
Conley, D. J., Stockenberg, A., Carman, R., Johnstone, R. W., Rahm, L., and Wulff, F.:
Sediment-water Nutrient Fluxes in the Gulf of Finland, Baltic Sea, Estuar. Coast. Shelf S., 45, 591–598, 1997.
Conley, D. J., Humborg, C., Rahm, L., Savchuk, O. P., and Wulff, F.:
Hypoxia in the Baltic Sea and Basin-Scale Changes in Phosphorus Biogeochemistry, Envrion. Sci. Technol., 36, 5315–5320, https://doi.org/10.1021/es025763w, 2002.
Conley, D. J., Carstensen, J., Ærtebjerg, G., Christensen, P. B., Dalsgaard, T., Hansen, J. L. S., and Josefson, A. B.:
LONG-TERM CHANGES AND IMPACTS OF HYPOXIA IN DANISH COASTAL WATERS, Ecol. Appl., 17, S165–S184, https://doi.org/10.1890/05-0766.1, 2007.
Conley, D. J., Björck, S., Bonsdorff, E., Carstensen, J., Destouni, G., Gustafsson, B. G., Hietanen, S., Kortekaas, M., Kuosa, H., Meier, H. E. M., Müller-Karulis, B., Nordberg, K., Norkko, A., Nürnberg, G., Pitkänen, H., Rabalais, N. N., Rosenberg, R., Savchuk, O. P., Slomp, C. P., Voss, M., Wulff, F., and Zillén, L.:
Hypoxia-Related Processes in the Baltic Sea, Environ. Sci. Technol., 43, 3412–3420, https://doi.org/10.1021/es802762a, 2009.
Conley, D. J., Carstensen, J., Aigars, J., Axe, P., Bonsdorff, E., Eremina, T., Haahti, B.-M., Humborg, C., Jonsson, P., Kotta, J., Lännegren, C., Larsson, U., Maximov, A., Medina, M. R., Lysiak-Pastuszak, E., Remeikaitė-Nikienė, N., Walve, J., Wilhelms, S., and Zillén, L.:
Hypoxia Is Increasing in the Coastal Zone of the Baltic Sea, Environ. Sci. Technol., 45, 6777–6783, https://doi.org/10.1021/es201212r, 2011.
Diaz, R. J. and Rosenberg, R.:
Spreading Dead Zones and Consequences for Marine Ecosystems, Science (80-.), 321, 926–929, https://doi.org/10.1126/science.1156401, 2008.
Eglīte, E., Lavrinovičs, A., Müller-Karulis, B., Aigars, J., and Poikāne, R.:
Nutrient turnover at the hypoxic boundary: flux measurements and model representation for the bottom water environment of the Gulf of Riga, Baltic Sea, Oceanologia, 56, 711–735, 2014.
EMODnet Bathymetry Consortium: EMODnet Digital Bathymetry (DTM), https://sextant.ifremer.fr/record/bb6a87dd-e579-4036-abe1-e649cea9881a/ (last access: 28 April 2021), 2020.
Estonian Environment Agency: KESE [data set], https://kese.envir.ee/kese/, last access: 4 April 2019.
Estonian Weather Service: Hydrological data [data set], https://www.ilmateenistus.ee/siseveed/ajaloolised-vaatlusandmed/vooluhulgad/, last access: 23 March 2022.
Fennel, K. and Testa, J. M.:
Biogeochemical Controls on Coastal Hypoxia, Annu. Rev. Mar. Sci., 11, 105–130, https://doi.org/10.1146/annurev-marine-010318-095138, 2019.
Groeskamp, S. and Iudicone, D.:
The Effect of Air-Sea Flux Products, Shortwave Radiation Depth Penetration, and Albedo on the Upper Ocean Overturning Circulation, Geophys. Res. Lett., 45, 9087–9097, https://doi.org/10.1029/2018GL078442, 2018.
Gröger, M., Arneborg, L., Dieterich, C., Höglund, A., and Meier, H. E. M.:
Summer hydrographic changes in the Baltic Sea, Kattegat and Skagerrak projected in an ensemble of climate scenarios downscaled with a coupled regional ocean–sea ice–atmosphere model, Clim. Dynam., 53, 5945–5966, https://doi.org/10.1007/s00382-019-04908-9, 2019.
Gustafsson, B. G., Schenk, F., Blenckner, T., Eilola, K., Meier, H. E. M., Müller-Karulis, B., Neumann, T., Ruoho-Airola, T., Savchuk, O. P., and Zorita, E.:
Reconstructing the Development of Baltic Sea Eutrophication 1850–2006, Ambio, 41, 534–548, 2012.
Hansson, M. and Viktorsson, L.:
REPORT OCEANOGRAPHY No. 70, 2020. Oxygen Survey in the Baltic Sea 2020 – Extent of Anoxia and Hypoxia, SMHI, ISSN 0283-1112,
1960–2020, 2020.
HELCOM:
Environment of the Baltic Sea area 1994–1998, Balt. Sea Environ. Proc. No. 82B, Helsinki Commission, ISSN 0357-2994, 215, 2002.
HELCOM:
Eutrophication in the Baltic Sea – An Integrated thematic assessment of the effects of nutrient enrichment and eutrophication in the Baltic Sea region, Balt. Sea Environ. Proc. No. 115B, Helsinki Commission, ISSN 0357-2994,
148, 2009.
HELCOM:
Manual for the Marine Monitoring in the COMBINE Programme of HELCOM, https://helcom.fi/action-areas/monitoring-and-assessment/monitoring-guidelines/combine-manual/ (last access: 21 June 2021), 2017.
HELCOM: HELCOM Thematic assessment of eutrophication 2011-2016. Baltic Sea Environment Proceedings No. 156, Baltic Marine Environment Protection Commission, ISSN 0357-2994, 2018a.
HELCOM: Sources and pathways of nutrients to the Baltic Sea. Baltic Sea Environment Proceedings No. 153, Baltic Marine Environment Protection Commission, ISSN 0357-2994, 2018b.
HELCOM: State of the Baltic Sea – Second HELCOM holistic assessment 2011–2016. Baltic Sea Environment Proceedings 155, Baltic Marine Environment Protection Commission, ISSN 0357-2994, 2018c.
HELCOM:
Inputs of nutrients to the sub-basins (2019), HELCOM core indicator report, https://helcom.fi/wp-content/uploads/2017/06/HELCOM-core-indicator-on-inputs-of-nutrients-for-period-1995-2019.pdf (last access: 10 January 2022), 2022.
Hersbach, H., Bell, B., Berrisford, P., Biavati, G., Horányi, A., Muñoz Sabater, J., Nicolas, J., Peubey, C., Radu, R., Rozum, I., Schepers, D., Simmons, A., Soci, C., Dee, D., and Thépaut, J.-N.:
ERA5 hourly data on single levels from 1979 to present, Copernicus Clim. Chang. Serv. Clim. Data Store [data set], https://doi.org/10.24381/cds.adbb2d47, 2018.
Hoy, A., Hänsel, S., and Maugeri, M.:
An endless summer: 2018 heat episodes in Europe in the context of secular temperature variability and change, Int. J. Climatol., 40, 6315–6336, https://doi.org/10.1002/joc.6582, 2020.
ICES: Oceanographic database [data set], https://www.ices.dk/data/dataset-collections/pages/default.aspx, last access: 16 April 2019.
IOC, SCOR and IAPSO: The International Thermodynamic Equation of Seawater – 2010: Calculation and Use of Thermodynamic Properties, Intergovernmental Oceanographic Commission, Manuals and Guides No. 56, UNESCO (English), 196 pp., 2010.
Jansson, A., Klais-Peets, R., Grinienė, E., Rubene, G., Semenova, A., Lewandowska, A., and Engström-Öst, J.:
Functional shifts in estuarine zooplankton in response to climate variability, Ecol. Evol., 10, 11591–11606, https://doi.org/10.1002/ece3.6793, 2020.
Johansson, J.:
Total and regional runoff to the Baltic Sea, HELCOM Balt. Sea Environ. Fact Sheets, Online, Helsinki Commission, https://helcom.fi/media/documents/BSEFS_Total-and-regional-runoff-to-the-Baltic-Sea-in-2015.pdf
(last access: 9 June 2022),
2016.
Jokinen, S. A., Virtasalo, J. J., Jilbert, T., Kaiser, J., Dellwig, O., Arz, H. W., Hänninen, J., Arppe, L., Collander, M., and Saarinen, T.:
A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20th century, Biogeosciences, 15, 3975–4001, https://doi.org/10.5194/bg-15-3975-2018, 2018.
Kabel, K., Moros, M., Porsche, C., Neumann, T., Adolphi, F., Andersen, T. J., Siegel, H., Gerth, M., Leipe, T., Jansen, E., and Damsté, J. S. S.:
Impact of climate change on the Baltic Sea ecosystem over the past 1,000 years, Nat. Clim. Change, 2, 871–874, 2012.
Karlson, K., Rosenberg, R., and Bonsdorff, E.:
Temporal and spatial large-scale effects of eutrophication and oxygen deficiency on benthic fauna in Scandinavian and Baltic waters: a review, edited by: Gibson, R. N. et al. Oceanogr. Mar. Biol. Ann. Rev., 40, 427–489, 2002.
Kniebusch, M., Meier, H. E. M., Neumann, T., and Börgel, F.:
Temperature Variability of the Baltic Sea Since 1850 and Attribution to Atmospheric Forcing Variables, J. Geophys. Res.-Oceans, 124, 4168–4187, https://doi.org/10.1029/2018JC013948, 2019.
Koop, K., Boynton, W. R., Wulff, F., and Carman, R.:
Sediment-water oxygen and nutrient exchanges along a depth gradient in the Baltic Sea, Mar. Ecol. Prog. Ser., 63, 65–77, 1990.
Kralj, M., Lipizer, M., Čermelj, B., Celio, M., Fabbro, C., Brunetti, F., Francé, J., Mozetič, P., and Giani, M.:
Hypoxia and dissolved oxygen trends in the northeastern Adriatic Sea (Gulf of Trieste), Deep-Sea Res. Pt. II, 164, 74–88, https://doi.org/10.1016/j.dsr2.2019.06.002, 2019.
Latvian Environment: Geology and Meteorology Center [data set], https://videscentrs.lvgmc.lv/, 2019.
Lehtoranta, J., Savchuk, O. P., Elken, J., Kim, D., Kuosa, H., Raateoja, M., Kauppila, P., Räike, A., and Pitkänen, H.:
Atmospheric forcing controlling inter-annual nutrient dynamics in the open Gulf of Finland, J. Marine Syst., 171, 4–20, 2017.
Liblik, T. and Lips, U.:
Variability of synoptic-scale quasi-stationary thermohaline stratification patterns in the Gulf of Finland in summer 2009, Ocean Sci., 8, 603–614, https://doi.org/10.5194/os-8-603-2012, 2012.
Liblik, T. and Lips, U.:
Stratification Has Strengthened in the Baltic Sea – An Analysis of 35 Years of Observational Data, Front. Earth. Sci., 7, 174, https://doi.org/10.3389/feart.2019.00174, 2019.
Liblik, T., Skudra, M., and Lips, U.:
On the buoyant sub-surface salinity maxima in the Gulf of Riga, Oceanologia, 59, 113–128, 2017.
Liblik, T., Naumann, M., Alenius, P., Hansson, M., Lips, U., Nausch, G., Tuomi, L., Wesslander, K., Laanemets, J., and Viktorsson, L.: Propagation of Impact of the Recent Major Baltic Inflows From the Eastern Gotland Basin to the Gulf of Finland, Front. Mar. Sci., 5, 222, https://doi.org/10.3389/fmars.2018.00222, 2018.
Liblik, T., Wu, Y., Fan, D., and Shang, D.:
Wind-driven stratification patterns and dissolved oxygen depletion off the Changjiang (Yangtze) Estuary, Biogeosciences, 17, 2875–2895, https://doi.org/10.5194/bg-17-2875-2020, 2020.
Lilover, M.-J., Lips, U., Laanearu, J., and Liljebladh, B.:
Flow regime in the Irbe Strait, Aquat. Sci., 60, 253–265, 1998.
Lips, U., Lilover, M.-J., Raudsepp, U., and Talpsepp, L.:
Water renewal processes and related hydrographic structures in the Gulf of Riga, in: Hydrographic studies within the Gulf of Riga Project, 1993–1994, edited by: Toompuu, A. and Elken, J., Estonian Marine Institute Report Series No. 1, 1–34, ISBN 9985-9058-0-6, 1995.
Lips, U., Zhurbas, V., Skudra, M., and Väli, G.:
A numerical study of circulation in the Gulf of Riga, Baltic Sea. Part I: Whole-basin gyres and mean currents, Cont. Shelf Res., 112, 1–13, 2016.
Lips, U., Laanemets, J., Lips, I., Liblik, T., Suhhova, I., and Suursaar, Ü.:
Wind-driven residual circulation and related oxygen and nutrient dynamics in the Gulf of Finland (Baltic Sea) in winter, Estuar. Coast. Shelf S., 195, 4–15, 2017.
Lukkari, K., Leivuori, M., Vallius, H., and Kotilainen, A.:
The chemical character and burial of phosphorus in shallow coastal sediments in the northeastern Baltic Sea, Biogeochemistry, 94, 141–162, https://doi.org/10.1007/s10533-009-9315-y, 2009.
Matthäus, W. and Franck, H.:
Characteristics of major Baltic inflows—a statistical analysis, Cont. Shelf Res., 12, 1375–1400, https://doi.org/doi:10.1016/0278-4343(92)90060-W, 1992.
Meier, H. E. M. and Saraiva, S.: Projected Oceanographical Changes in the Baltic Sea until 2100, Oxford Research Encyclopedia of Climate Science, https://doi.org/10.1093/acrefore/9780190228620.013.699, 2020.
Meier, H. E. M., Andersson, H. C., Eilola, K., Gustafsson, B. G., Kuznetsov, I., Müller-Karulis, B., Neumann, T., and Savchuk, O. P.:
Hypoxia in future climates: A model ensemble study for the Baltic Sea, Geophys. Res. Lett., 38, L24608, https://doi.org/10.1029/2011GL049929, 2011.
Meier, H. E. M., Väli, G., Naumann, M., Eilola, K., and Frauen, C.:
Recently Accelerated Oxygen Consumption Rates Amplify Deoxygenation in the Baltic Sea, J. Geophys. Res.-Oceans, 123, 3227–3240, https://doi.org/10.1029/2017JC013686, 2018.
Murphy, R. R., Kemp, W. M., and Ball, W. P.:
Long-Term Trends in Chesapeake Bay Seasonal Hypoxia, Stratification, and Nutrient Loading, Estuar. Coast., 34, 1293–1309, https://doi.org/10.1007/s12237-011-9413-7, 2011.
Ojaveer, E. (Ed.): Ecosystem of the Gulf of Riga between 1920 and 1990, Estonian Academy Publishers, Tallinn, 1995.
Olli, K. and Heiskanen, A.-S.:
Seasonal stages of phytoplankton community structure and sinking loss in the Gulf of Riga, J. Marine Syst., 23, 165–184, https://doi.org/10.1016/S0924-7963(99)00056-1, 1999.
Omstedt, A., Meuller, L., and Nyberg, L.:
Interannual, Seasonal and Regional Variations of Precipitation and Evaporation over the Baltic Sea, Ambio, 26, 484–492, 1997.
Petrov, V.:
Water balance and water exchange between the Gulf of Riga and the Baltic Proper, Sb. Rab. Rizhskoj GO, 18, 20–40, 1979.
Pitkänen, H., Lehtoranta, J., and Räike, A.:
Internal Nutrient Fluxes Counteract Decreases in External Load: The Case of the Estuarial Eastern Gulf of Finland, Baltic Sea, Ambio, 30, 195–201, https://doi.org/10.1579/0044-7447-30.4.195, 2001.
Powilleit, M. and Kube, J.:
Effects of severe oxygen depletion on macrobenthos in the Pomeranian Bay (southern Baltic Sea): a case study in a shallow, sublittoral habitat characterised by low species richness, J. Sea Res., 42, 221–234, 1999.
Purina, I., Labucis, A., Barda, I., Jurgensone, I., and Aigars, J.:
Primary productivity in the Gulf of Riga (Baltic Sea) in relation to phytoplankton species and nutrient variability, Oceanologia, 60, 544–552, https://doi.org/10.1016/j.oceano.2018.04.005, 2018.
Puttonen, I., Mattila, J., Jonsson, P., Karlsson, O. M., Kohonen, T., Kotilainen, A., Lukkari, K., Malmaeus, J. M., and Rydin, E.:
Distribution and estimated release of sediment phosphorus in the northern Baltic Sea archipelagos, Estuar. Coast. Shelf S., 145, 9–21, https://doi.org/10.1016/j.ecss.2014.04.010, 2014.
Puttonen, I., Kohonen, T., and Mattila, J.:
Factors controlling phosphorus release from sediments in coastal archipelago areas, Mar. Pollut. Bull., 108, 77–86, https://doi.org/10.1016/j.marpolbul.2016.04.059, 2016.
Raudsepp, U. and Elken, J.:
Application of the GFDL circulation model for the Gulf of Riga, in: Hydrographic studies within the Gulf of Riga Project, 1993–1994, edited by: Toompuu, A. and Elken, J., Estonian Marine Institute Report Series No. 1, 143–176, ISBN 9985-9058-0-6, 1995.
Reusch, T. B. H., Dierking, J., Andersson, H. C., Bonsdorff, E., Carstensen, J., Casini, M., Czajkowski, M., Hasler, B., Hinsby, K., Hyytiäinen, K., Johannesson, K., Jomaa, S., Jormalainen, V., Kuosa, H., Kurland, S., Laikre, L., MacKenzie, B. R., Margonski, P., Melzner, F., Oesterwind, D., Ojaveer, H., Refsgaard, J. C., Sandström, A., Schwarz, G., Tonderski, K., Winder, M., and Zandersen, M.:
The Baltic Sea as a time machine for the future coastal ocean, Sci. Adv., 4, eaar8195, https://doi.org/10.1126/sciadv.aar8195, 2018.
Ruosteenoja, K., Vihma, T., and Venäläinen, A.:
Projected Changes in European and North Atlantic Seasonal Wind Climate Derived from CMIP5 Simulations, J. Climate, 32, 6467–6490, https://doi.org/10.1175/JCLI-D-19-0023.1, 2019.
Saraiva, S., Markus Meier, H. E., Andersson, H., Höglund, A., Dieterich, C., Gröger, M., Hordoir, R., and Eilola, K.:
Baltic Sea ecosystem response to various nutrient load scenarios in present and future climates, Clim. Dynam., 52, 3369–3387, https://doi.org/10.1007/s00382-018-4330-0, 2019a.
Saraiva, S., Meier, H. E. M., Andersson, H., Höglund, A., Dieterich, C., Gröger, M., Hordoir, R., and Eilola, K.:
Uncertainties in Projections of the Baltic Sea Ecosystem Driven by an Ensemble of Global Climate Models, Front. Earth Sci., 6, 244, https://doi.org/10.3389/feart.2018.00244, 2019b.
Savchuk, O. P.:
Large-Scale Nutrient Dynamics in the Baltic Sea, 1970–2016, Front. Mar. Sci., 5, https://doi.org/10.3389/fmars.2018.00095, 2018.
Schinke, H. and Matthäus, W.:
On the causes of major Baltic inflows – an analysis of long time series, Cont. Shelf Res., 18, 67–97, https://doi.org/10.1016/S0278-4343(97)00071-X, 1998.
Schlitzer, R.: Ocean Data View, [code] https://odv.awi.de (last access: 9 January 2020), 2019.
Schmale, O., Krause, S., Holtermann, P., Power Guerra, N. C., and Umlauf, L.:
Dense bottom gravity currents and their impact on pelagic methanotrophy at oxic/anoxic transition zones, Geophys. Res. Lett., 43, 5225–5232, https://doi.org/10.1002/2016GL069032, 2016.
SeaDataNet: SeaDataNet Pan-European infrastructure for ocean and marine data management
[data set], http://www.seadatanet.org, last access: 9 April 2019.
Séférian, R., Baek, S., Boucher, O., Dufresne, J.-L., Decharme, B., Saint-Martin, D., and Roehrig, R.:
An interactive ocean surface albedo scheme (OSAv1.0): formulation and evaluation in ARPEGE-Climat (V6.1) and LMDZ (V5A), Geosci. Model Dev., 11, 321–338, https://doi.org/10.5194/gmd-11-321-2018, 2018.
Simpson, J. H., Brown, J., Matthews, J., and Allen, G.:
Tidal Straining, Density Currents, and Stirring in the Control of Estuarine Stratification, Estuaries, 13, 125–132, https://doi.org/10.2307/1351581, 1990.
Skudra, M. and Lips, U.:
Characteristics and inter-annual changes in temperature, salinity and density distribution in the Gulf of Riga, Oceanologia, 59, 37–48, 2017.
Soosaar, E., Maljutenko, I., Raudsepp, U., and Elken, J.:
An investigation of anticyclonic circulation in the southern Gulf of Riga during the spring period, Cont. Shelf Res., 78, 75–84, https://doi.org/10.1016/j.csr.2014.02.009, 2014.
Spilling, K., Olli, K., Lehtoranta, J., Kremp, A., Tedesco, L., Tamelander, T., Klais, R., Peltonen, H., and Tamminen, T.:
Shifting Diatom—Dinoflagellate Dominance During Spring Bloom in the Baltic Sea and its Potential Effects on Biogeochemical Cycling, Front. Mar. Sci., 5, 92–108, https://doi.org/10.3389/fmars.2018.00327, 2018.
Stiebrins, O. and Väling, P.:
Bottom sediments of the Gulf of Riga, Geol. Surv. Latv. Riga, 4, ISBN 9984-9130-0-7, 1996.
Stipa, T., Tamminen, T., and Seppälä, J.:
On the creation and maintenance of stratification in the Gulf of Riga, J. Marine Syst., 23, 27–49, 1999.
Stoicescu, S.-T., Lips, U., and Liblik, T.:
Assessment of Eutrophication Status Based on Sub-Surface Oxygen Conditions in the Gulf of Finland (Baltic Sea), Front. Mar. Sci., 6, 54, https://doi.org/10.3389/fmars.2019.00054, 2019.
Stonevičius, E., Rimkus, E., Štaras, A., Kažys, J., and Valiuškevičius, G.:
Climate change impact on the Nemunas River basin hydrology in the 21st century, Boreal Environ. Res., 22, 49–65, 2017.
Ukrainskii, V. V. and Popov, Y. I.:
Climatic and hydrophysical conditions of the development of hypoxia in waters of the northwest shelf of the Black Sea, Phys. Oceanogr., 19, 140, https://doi.org/10.1007/s11110-009-9046-6, 2009.
van Helmond, N. A. G. M., Robertson, E. K., Conley, D. J., Hermans, M., Humborg, C., Kubeneck, L. J., Lenstra, W. K., and Slomp, C. P.:
Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea, Biogeosciences, 17, 2745–2766, https://doi.org/10.5194/bg-17-2745-2020, 2020.
Virtanen, E. A., Norkko, A., Nyström Sandman, A., and Viitasalo, M.:
Identifying areas prone to coastal hypoxia – the role of topography, Biogeosciences, 16, 3183–3195, https://doi.org/10.5194/bg-16-3183-2019, 2019.
Walve, J., Sandberg, M., Larsson, U., and Lännergren, C.:
A Baltic Sea estuary as a phosphorus source and sink after drastic load reduction: seasonal and long-term mass balances for the Stockholm inner archipelago for 1968–2015, Biogeosciences, 15, 3003–3025, https://doi.org/10.5194/bg-15-3003-2018, 2018.
Wasmund, N., Nausch, G., Gerth, M., Busch, S., Burmeister, C., Hansen, R., and Sadkowiak, B.:
Extension of the growing season of phytoplankton in the western Baltic Sea in response to climate change, Mar. Ecol.-Prog. Ser., 622, 1–16, 2019.
Wu, J.:
Wind-stress coefficients over sea surface from breeze to hurricane, J. Geophys. Res.-Oceans, 87, 9704–9706, https://doi.org/10.1029/JC087iC12p09704, 1982.
Yurkovskis, A.:
Long-term land-based and internal forcing of the nutrient state of the Gulf of Riga (Baltic Sea), J. Marine Syst., 50, 181–197, https://doi.org/10.1016/j.jmarsys.2004.01.004, 2004.
Yurkovskis, A., Wulff, F., Rahm, L., Andruzaitis, A., and Rodriguez-Medina, M.:
A Nutrient Budget of the Gulf of Riga; Baltic Sea, Estuar. Coast. Shelf S., 37, 113–127, https://doi.org/10.1006/ecss.1993.1046, 1993.
Zhang, J., Gilbert, D., Gooday, A. J., Levin, L., Naqvi, S. W. A., Middelburg, J. J., Scranton, M., Ekau, W., Peña, A., Dewitte, B., Oguz, T., Monteiro, P. M. S., Urban, E., Rabalais, N. N., Ittekkot, V., Kemp, W. M., Ulloa, O., Elmgren, R., Escobar-Briones, E., and Van der Plas, A. K.:
Natural and human-induced hypoxia and consequences for coastal areas: synthesis and future development, Biogeosciences, 7, 1443–1467, https://doi.org/10.5194/bg-7-1443-2010, 2010.
Short summary
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.
Coastal basins with high input of nutrients often suffer from oxygen deficiency. In summer 2018,...
Altmetrics
Final-revised paper
Preprint