Articles | Volume 21, issue 6
https://doi.org/10.5194/bg-21-1433-2024
© Author(s) 2024. 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-21-1433-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
20 Mar 2024
Research article |
| 20 Mar 2024
| 20 Mar 2024
Oceanographic processes driving low-oxygen conditions inside Patagonian fjords
Pamela Linford
Programa de Doctorado en Ciencias, Mención Conservación y Manejo de Recursos Naturales, Universidad de Los Lagos, Puerto Montt, Chile
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Center for Oceanographic Research COPAS Sur-Austral and COPAS COASTAL, Universidad de Concepción, Concepción, Chile
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Center for Oceanographic Research COPAS Sur-Austral and COPAS COASTAL, Universidad de Concepción, Concepción, Chile
Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile
Paulina Montero
Center for Oceanographic Research COPAS Sur-Austral and COPAS COASTAL, Universidad de Concepción, Concepción, Chile
Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile
Patricio A. Díaz
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
CeBiB, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Claudia Aracena
Centro de Investigación en Recursos Naturales y Sustentabilidad, Universidad Bernardo O'Higgins, Avenida Viel 1497, Santiago, Chile
Laboratorio Costero de Recursos Acuáticos de Calfuco, Universidad Austral de Chile, Valdivia, Chile
Elías Pinilla
Instituto de Fomento Pesquero (IFOP), CTPA Putemún, Castro, Chile
Department of Civil and Environmental Engineering, University of Maine, Orono, ME, USA
Facundo Barrera
Fundación Bariloche and CONICET, San Carlos de Bariloche, Argentina
Centro Austral de Investigaciones Científicas (CADIC), CONICET, Bernardo Houssay 200, Ushuaia, Argentina
Manuel Castillo
Centro de Observación Marino para Estudios de Riesgos del Ambiente Costero, Universidad de Valparaíso, Valparaíso, Chile
Aida Alvera-Azcárate
AGO-GHER, University of Liège, Liège, Belgium
Mónica Alvarado
Servicio Hidrográfico y Oceanográfico de la Armada de Chile, Valparaíso, Chile
Gabriel Soto
Instituto de Fomento Pesquero (IFOP), CTPA Putemún, Castro, Chile
Cécile Pujol
AGO-GHER, University of Liège, Liège, Belgium
Camila Schwerter
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Sara Arenas-Uribe
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Pilar Navarro
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Guido Mancilla-Gutiérrez
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Robinson Altamirano
Centro i-mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile
Javiera San Martín
Instituto de Fomento Pesquero (IFOP), CTPA Putemún, Castro, Chile
Camila Soto-Riquelme
Instituto de Fomento Pesquero (IFOP), CTPA Putemún, Castro, Chile
Related authors
Cécile Pujol, Alexander Barth, Iván Pérez-Santos, Pamela Muñoz-Linford, and Aida Alvera-Azcárate
EGUsphere, https://doi.org/10.5194/egusphere-2025-1421, https://doi.org/10.5194/egusphere-2025-1421, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
Marine heatwaves and cold spells are periods of extreme sea temperatures. This study focuses on Chilean Northern Patagonia, a fjord region vulnerable due to its aquaculture. It aims to understand these events' distribution and identify the most affected basins. Results show higher intensity in enclosed areas like Reloncaví Sound and Puyuhuapi Fjord. Marine heatwaves are becoming more frequent over time, while cold spells are decreasing.
Aida Alvera-Azcárate, Dimitry Van der Zande, Alexander Barth, Antoine Dille, Joppe Massant, and Jean-Marie Beckers
Ocean Sci., 21, 787–805, https://doi.org/10.5194/os-21-787-2025, https://doi.org/10.5194/os-21-787-2025, 2025
Short summary
Short summary
This work presents an approach for increasing the spatial resolution of satellite data and interpolating gaps due to cloud cover, using a method called DINEOF (data-interpolating empirical orthogonal functions). The method is tested on turbidity and chlorophyll-a concentration data in the Belgian coastal zone and the North Sea. The results show that we are able to improve the spatial resolution of these data in order to perform analyses of spatial and temporal variability in coastal regions.
Bayoumy Mohamed, Alexander Barth, Dimitry Van der Zande, and Aida Alvera-Azcárate
EGUsphere, https://doi.org/10.5194/egusphere-2025-1578, https://doi.org/10.5194/egusphere-2025-1578, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
We quantified the role of climate change and internal variability on marine heatwaves (MHWs) in the North Sea over more than four decades (1982–2024). A key finding is the 2013 climate shift, which was associated with increased warming and MHWs. Long-term warming accounted for 80 % of the observed trend in MHW frequency. The most intense MHW event in May 2024 was attributed to an anomalous anticyclonic atmospheric circulation. We also explored the impact of MHWs on chlorophyll concentrations.
Cécile Pujol, Alexander Barth, Iván Pérez-Santos, Pamela Muñoz-Linford, and Aida Alvera-Azcárate
EGUsphere, https://doi.org/10.5194/egusphere-2025-1421, https://doi.org/10.5194/egusphere-2025-1421, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
Marine heatwaves and cold spells are periods of extreme sea temperatures. This study focuses on Chilean Northern Patagonia, a fjord region vulnerable due to its aquaculture. It aims to understand these events' distribution and identify the most affected basins. Results show higher intensity in enclosed areas like Reloncaví Sound and Puyuhuapi Fjord. Marine heatwaves are becoming more frequent over time, while cold spells are decreasing.
Ehsan Mehdipour, Hongyan Xi, Alexander Barth, Aida Alvera-Azcárate, Adalbert Wilhelm, and Astrid Bracher
EGUsphere, https://doi.org/10.5194/egusphere-2025-112, https://doi.org/10.5194/egusphere-2025-112, 2025
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
Short summary
Short summary
Phytoplankton are vital for marine ecosystems and nutrient cycling, detectable by optical satellites. Data gaps caused by clouds and other non-optimal conditions limit comprehensive analyses like trend monitoring. This study evaluated DINCAE and DINEOF gap-filling methods for reconstructing chlorophyll-a datasets, including total chlorophyll-a and five major phytoplankton groups. Both methods showed robust reconstruction capabilities, aiding pattern detection and long-term ocean colour analysis.
Macarena Díaz-Astudillo, Manuel Castillo, Pedro A. Figueroa, Leonardo R. Castro, Ramiro Riquelme-Bugueño, Iván Pérez-Santos, Oscar Pizarro, and Gonzalo S. Saldías
EGUsphere, https://doi.org/10.5194/egusphere-2025-417, https://doi.org/10.5194/egusphere-2025-417, 2025
Short summary
Short summary
Submarine canyons are known hotspots of marine productivity and biodiversity, but we don’t fully understand why. We studied a submarine canyon located in central Chile and found that it’s a highly dynamic environment in both space and time. We think that the alternating currents and the contrasting distribution of zooplankton within the canyon might interact to promote zooplankton retention. Our results help to explain why submarine canyons host such high zooplankton diversity and abundance.
Matjaž Zupančič Muc, Vitjan Zavrtanik, Alexander Barth, Aida Alvera-Azcarate, Matjaž Ličer, and Matej Kristan
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2024-208, https://doi.org/10.5194/gmd-2024-208, 2025
Preprint under review for GMD
Short summary
Short summary
Accurate sea surface temperature data (SST) is crucial for weather forecasting and climate modeling, but satellite observations are often incomplete. We developed a new method called CRITER, which uses machine learning to fill in the gaps in SST data. Our two-stage approach reconstructs large-scale patterns and refines details. Tested on Mediterranean, Adriatic, and Atlantic seas data, CRITER outperforms current methods, reducing errors by up to 44 %.
Pilar Aparicio-Rizzo, Dagoberto Poblete-Cballero, Cristian Vera-Bastidas, Iván Pérez-Santos, and Daniel Varela
EGUsphere, https://doi.org/10.5194/egusphere-2024-3951, https://doi.org/10.5194/egusphere-2024-3951, 2025
Short summary
Short summary
This work combines hyperspectral sensors and unmanned aerial vehicles to detect and differentiate microalgal species from optical data on Patagonia fjords at local scale. The results show differences between in situ hyperspectral signals, especially at blue, green, and red to near-infrared spectra, distinguishing between diatoms and dinoflagellates species. These tools are mainly useful in coastal areas where the cloudiness and geographic heterogeneity make satellite data acquisition difficult.
Alexander Barth, Julien Brajard, Aida Alvera-Azcárate, Bayoumy Mohamed, Charles Troupin, and Jean-Marie Beckers
Ocean Sci., 20, 1567–1584, https://doi.org/10.5194/os-20-1567-2024, https://doi.org/10.5194/os-20-1567-2024, 2024
Short summary
Short summary
Most satellite observations have gaps, for example, due to clouds. This paper presents a method to reconstruct missing data in satellite observations of the chlorophyll a concentration in the Black Sea. Rather than giving a single possible reconstructed field, the discussed method provides an ensemble of possible reconstructions using a generative neural network. The resulting ensemble is validated using techniques from numerical weather prediction and ocean modelling.
Manal Hamdeno, Aida Alvera-Azcárate, George Krokos, and Ibrahim Hoteit
Ocean Sci., 20, 1087–1107, https://doi.org/10.5194/os-20-1087-2024, https://doi.org/10.5194/os-20-1087-2024, 2024
Short summary
Short summary
Our study focuses on the characteristics of MHWs in the Red Sea during the last 4 decades. Using satellite-derived sea surface temperatures (SSTs), we found a clear warming trend in the Red Sea since 1994, which has intensified significantly since 2016. This SST rise was associated with an increase in the frequency and days of MHWs. In addition, a correlation was found between the frequency of MHWs and some climate modes, which was more pronounced in some years of the study period.
Julio Salcedo-Castro, Antonio Olita, Freddy Saavedra, Gonzalo S. Saldías, Raúl C. Cruz-Gómez, and Cristian D. De la Torre Martínez
Ocean Sci., 19, 1687–1703, https://doi.org/10.5194/os-19-1687-2023, https://doi.org/10.5194/os-19-1687-2023, 2023
Short summary
Short summary
Considering the relevance and impact of river discharges on the coastal environment, it is necessary to understand the processes associated with river plume dynamics in different regions and at different scales. Modeling studies focused on the eastern Pacific coast under the influence of the Humboldt Current are scarce. Here, we conduct for the first time an interannual modeling study of two river plumes off central Chile and discuss their characteristics.
Alexander Barth, Aida Alvera-Azcárate, Charles Troupin, and Jean-Marie Beckers
Geosci. Model Dev., 15, 2183–2196, https://doi.org/10.5194/gmd-15-2183-2022, https://doi.org/10.5194/gmd-15-2183-2022, 2022
Short summary
Short summary
Earth-observing satellites provide routine measurement of several ocean parameters. However, these datasets have a significant amount of missing data due to the presence of clouds or other limitations of the employed sensors. This paper describes a method to infer the value of the missing satellite data based on a convolutional autoencoder (a specific type of neural network architecture). The technique also provides a reliable error estimate of the interpolated value.
Estrella Olmedo, Verónica González-Gambau, Antonio Turiel, Cristina González-Haro, Aina García-Espriu, Marilaure Gregoire, Aida Álvera-Azcárate, Luminita Buga, and Marie-Hélène Rio
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2021-364, https://doi.org/10.5194/essd-2021-364, 2021
Revised manuscript not accepted
Short summary
Short summary
We present the first dedicated satellite salinity product in the Black Sea. We use the measurements provided by the European Soil Moisture and Ocean Salinity mission. We introduce enhanced algorithms for dealing with the contamination produced by the Radio Frequency Interferences that strongly affect this basin. We also provide a complete quality assessment of the new product and give an estimated accuracy of it.
Alexander Barth, Aida Alvera-Azcárate, Matjaz Licer, and Jean-Marie Beckers
Geosci. Model Dev., 13, 1609–1622, https://doi.org/10.5194/gmd-13-1609-2020, https://doi.org/10.5194/gmd-13-1609-2020, 2020
Short summary
Short summary
DINCAE is a method for reconstructing missing data in satellite datasets using a neural network. Satellite observations working in the optical and infrared bands are affected by clouds, which obscure part of the ocean underneath. In this paper, a neural network with the structure of a convolutional auto-encoder is developed to reconstruct the missing data based on the available cloud-free pixels in satellite images.
Iván Pérez-Santos, Romanet Seguel, Wolfgang Schneider, Pamela Linford, David Donoso, Eduardo Navarro, Constanza Amaya-Cárcamo, Elías Pinilla, and Giovanni Daneri
Ocean Sci., 15, 1247–1266, https://doi.org/10.5194/os-15-1247-2019, https://doi.org/10.5194/os-15-1247-2019, 2019
Short summary
Short summary
Satellite wind data were used to understand surface wind variability in the eastern austral Pacific Ocean, a region dominated generally by strong westerlies, but the empirical orthogonal function demonstrated that wind variability was dominated by a synoptic scale. Nighttime heatwave events were detected to produce air temperature maxima which exceeded the normal midday maxima caused by solar radiation. Downwelling conditions prevailed in the study region due to onshore Ekman transport.
Iván Pérez-Santos, Leonardo Castro, Lauren Ross, Edwin Niklitschek, Nicolás Mayorga, Luis Cubillos, Mariano Gutierrez, Eduardo Escalona, Manuel Castillo, Nicolás Alegría, and Giovanni Daneri
Ocean Sci., 14, 1185–1206, https://doi.org/10.5194/os-14-1185-2018, https://doi.org/10.5194/os-14-1185-2018, 2018
Short summary
Short summary
Fjord systems play an important role in primary production and carbon export. Acoustic, hydrographic and in situ abundance measurements were used to study macrozooplankton assemblages at 44.7° S. Diel vertical migration of zooplankton stopped at the hypoxic boundary layer and apparently did not tolerate the hypoxic conditions. Turbulence appears to be the oceanographic process that contributes to vertical mixing around the sill, helping the interchange of nutrients, feeding and carbon export.
Manuel I. Castillo, Oscar Pizarro, Nadin Ramírez, and Mario Cáceres
Ocean Sci., 13, 145–160, https://doi.org/10.5194/os-13-145-2017, https://doi.org/10.5194/os-13-145-2017, 2017
Short summary
Short summary
Here we present the results of an intensive physical oceanography study conducted in the Reloncavi fjord (41.5º S, 72.5º W) which was focused on the sub-inertial timescale. The along-fjord currents presented 3-day oscillations which were consistent with the natural internal period of oscillation of the fjord basin (internal seiche). This oscillation could explain more than 44 % of the 3-day variability and contributed with kinetic energy levels as large as the tidal currents.
Manuel I. Castillo, Ursula Cifuentes, Oscar Pizarro, Leif Djurfeldt, and Mario Caceres
Ocean Sci., 12, 533–544, https://doi.org/10.5194/os-12-533-2016, https://doi.org/10.5194/os-12-533-2016, 2016
Short summary
Short summary
The upper layer of the Reloncaví fjord, Chile, shows a continuous stratification year-round. Nevertheless, the vertical salt flux seems to be balanced by the horizontal salt flux, which maintains the amount of salt into the fjord nearly as a steady state. The upper layer shows a flushing time of about 3 days.
J.-M. Beckers, A. Barth, I. Tomazic, and A. Alvera-Azcárate
Ocean Sci., 10, 845–862, https://doi.org/10.5194/os-10-845-2014, https://doi.org/10.5194/os-10-845-2014, 2014
Related subject area
Biogeochemistry: Coastal Ocean
Ocean alkalinity enhancement (OAE) does not cause cellular stress in a phytoplankton community of the subtropical Atlantic Ocean
Reviews and syntheses: On increasing hypoxia in eastern boundary upwelling systems – zooplankton under metabolic stress
Technical note: Testing a new approach for the determination of N2 fixation rates by coupling a membrane equilibrator to a mass spectrometer for long-term observations
Long-term variations in pH in coastal waters along the Korean Peninsula
The effect of carbonate mineral additions on biogeochemical conditions in surface sediments and benthic–pelagic exchange fluxes
Evaluating ocean alkalinity enhancement as a carbon dioxide removal strategy in the North Sea
Assessing the impacts of simulated ocean alkalinity enhancement on viability and growth of nearshore species of phytoplankton
Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement
High metabolic zinc demand within native Amundsen and Ross sea phytoplankton communities determined by stable isotope uptake rate measurements
The influence of zooplankton and oxygen on the particulate organic carbon flux in the Benguela Upwelling System
Reviews and syntheses: Biological indicators of low-oxygen stress in marine water-breathing animals
Temperature-enhanced effects of iron on Southern Ocean phytoplankton
Riverine nutrient impact on global ocean nitrogen cycle feedbacks and marine primary production in an Earth system model
Effects of Submarine Groundwater on Nutrient Concentration and Primary Production in a Deep Bay of the Japan Sea
The Northeast Greenland Shelf as a potential late-summer CO2 source to the atmosphere
Spring-neap tidal cycles modulate the strength of the carbon source at the estuary-coast interface
Technical note: Ocean Alkalinity Enhancement Pelagic Impact Intercomparison Project (OAEPIIP)
Estimates of carbon sequestration potential in an expanding Arctic fjord (Hornsund, Svalbard) affected by dark plumes of glacial meltwater
An assessment of ocean alkalinity enhancement using aqueous hydroxides: kinetics, efficiency, and precipitation thresholds
Dissolved nitric oxide in the lower Elbe Estuary and the Port of Hamburg area
The bacteria-protist link as a main route of dissolved organic matter across contrasting productivity areas in the Patagonian Shelf
Variable contribution of wastewater treatment plant effluents to downstream nitrous oxide concentrations and emissions
Depositional controls and budget of organic carbon burial in fine-grained sediments of the North Sea – the Helgoland Mud Area as a test field
Improved understanding of eutrophication trends, indicators and problem areas using machine learning
Distribution of nutrients and dissolved organic matter in a eutrophic equatorial estuary: the Johor River and the East Johor Strait
Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022
Investigating the effect of silicate- and calcium-based ocean alkalinity enhancement on diatom silicification
Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment
Quantification and mitigation of bottom-trawling impacts on sedimentary organic carbon stocks in the North Sea
Influence of ocean alkalinity enhancement with olivine or steel slag on a coastal plankton community in Tasmania
Multi-model comparison of trends and controls of near-bed oxygen concentration on the northwest European continental shelf under climate change
Picoplanktonic methane production in eutrophic surface waters
Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea
Hypoxia also occurs in small highly turbid estuaries: the example of the Charente (Bay of Biscay)
Seasonality and response of ocean acidification and hypoxia to major environmental anomalies in the southern Salish Sea, North America (2014–2018)
Above- and belowground plant mercury dynamics in a salt marsh estuary in Massachusetts, USA
Variability and drivers of carbonate chemistry at shellfish aquaculture sites in the Salish Sea, British Columbia
Unusual Hemiaulus bloom influences ocean productivity in Northeastern US Shelf waters
Insights into carbonate environmental conditions in the Chukchi Sea
UAV approaches for improved mapping of vegetation cover and estimation of carbon storage of small saltmarshes: examples from Loch Fleet, northeast Scotland
Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
Marine anoxia initiates giant sulfur-oxidizing bacterial mat proliferation and associated changes in benthic nitrogen, sulfur, and iron cycling in the Santa Barbara Basin, California Borderland
Uncertainty in the evolution of northwestern North Atlantic circulation leads to diverging biogeochemical projections
The additionality problem of ocean alkalinity enhancement
Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings
Revisiting the applicability and constraints of molybdenum- and uranium-based paleo redox proxies: comparing two contrasting sill fjords
Influence of a small submarine canyon on biogenic matter export flux in the lower St. Lawrence Estuary, eastern Canada
Single-celled bioturbators: benthic foraminifera mediate oxygen penetration and prokaryotic diversity in intertidal sediment
Assessing impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase area, Okayama Prefecture, and Shizugawa Bay, Miyagi Prefecture, Japan
Multiple nitrogen sources for primary production inferred from δ13C and δ15N in the southern Sea of Japan
Librada Ramírez, Leonardo J. Pozzo-Pirotta, Aja Trebec, Víctor Manzanares-Vázquez, José L. Díez, Javier Arístegui, Ulf Riebesell, Stephen D. Archer, and María Segovia
Biogeosciences, 22, 1865–1886, https://doi.org/10.5194/bg-22-1865-2025, https://doi.org/10.5194/bg-22-1865-2025, 2025
Short summary
Short summary
We studied the potential effects of increasing ocean alkalinity on a natural plankton community in subtropical waters of the Atlantic near Gran Canaria, Spain. Alkalinity is the capacity of water to resist acidification, and plankton are usually microscopic plants (phytoplankton) and animals (zooplankton), often less than 2.5 cm in length. This study suggests that increasing ocean alkalinity did not have a significant negative impact on the plankton community studied.
Leissing Frederick, Mauricio A. Urbina, and Ruben Escribano
Biogeosciences, 22, 1839–1852, https://doi.org/10.5194/bg-22-1839-2025, https://doi.org/10.5194/bg-22-1839-2025, 2025
Short summary
Short summary
Evidence shows that due to global warming, zooplankton inhabiting the coastal upwelling zone are exposed to increasing hypoxia affecting their physiology, metabolism, and population dynamics. The adaptive responses of zooplankton to cope with mild/severe hypoxia may depend on trade-offs with other metabolic/energy demands, implying less energy for growth, feeding, and reproduction, with ecological consequences for the zooplankton population and the marine food web.
Sören Iwe, Oliver Schmale, and Bernd Schneider
Biogeosciences, 22, 1767–1779, https://doi.org/10.5194/bg-22-1767-2025, https://doi.org/10.5194/bg-22-1767-2025, 2025
Short summary
Short summary
We present a novel method for quantifying N2 fixation by cyanobacteria, which is crucial in Baltic Sea eutrophication. Our Gas Equilibrium – Membrane-Inlet Mass Spectrometer (GE-MIMS), designed for operation on voluntary observing ships (VOSs), enables large-scale monitoring of surface water N2 depletion caused by N2 fixation. Laboratory tests confirm the device’s accuracy and precision, ensuring that it can complement current methods and contribute valuable data for better understanding N2 fixation in the Baltic Sea.
Yong-Woo Lee, Mi-Ok Park, Seong-Gil Kim, Tae-Hoon Kim, Yong Hwa Oh, Sang Heon Lee, and DongJoo Joung
Biogeosciences, 22, 675–690, https://doi.org/10.5194/bg-22-675-2025, https://doi.org/10.5194/bg-22-675-2025, 2025
Short summary
Short summary
Long-term pH variation in coastal waters along the Korean Peninsula was assessed for the first time, and it exhibited no significant pH change over an 11-year period. This contrasts with the ongoing pH decline in open oceans and other coastal areas. Analysis of environmental data showed that pH is mainly controlled by dissolved oxygen in bottom waters. This suggests that ocean warming could cause a pH decline in Korean coastal waters, affecting many fish and seaweed aquaculture operations.
Kadir Biçe, Tristen Myers Stewart, George G. Waldbusser, and Christof Meile
Biogeosciences, 22, 641–657, https://doi.org/10.5194/bg-22-641-2025, https://doi.org/10.5194/bg-22-641-2025, 2025
Short summary
Short summary
We studied the effect of addition of carbonate minerals on coastal sediments. We carried out laboratory experiments to quantify the dissolution kinetics and integrated these observations into a numerical model that describes biogeochemical cycling in surficial sediments. Using the model, we demonstrate the buffering effect of the mineral additions and their duration. We quantify the effect under different environmental conditions and assess the potential for increased atmospheric CO2 uptake.
Feifei Liu, Ute Daewel, Jan Kossack, Kubilay Timur Demir, Helmuth Thomas, and Corinna Schrum
EGUsphere, https://doi.org/10.5194/egusphere-2025-81, https://doi.org/10.5194/egusphere-2025-81, 2025
Short summary
Short summary
Ocean Alkalinity Enhancement boosts oceanic CO₂ absorption, offering a climate solution. Using a regional model, we examined OAE in the North Sea, revealing that shallow coastal areas achieve higher CO₂ uptake than offshore, where alkalinity is more susceptible to deep-ocean loss. Long-term carbon storage is limited, and pH shifts vary by location. Our findings guide OAE deployment to optimize carbon removal while minimizing ecological effects, supporting global climate mitigation efforts.
Jessica L. Oberlander, Mackenzie E. Burke, Cat A. London, and Hugh L. MacIntyre
Biogeosciences, 22, 499–512, https://doi.org/10.5194/bg-22-499-2025, https://doi.org/10.5194/bg-22-499-2025, 2025
Short summary
Short summary
Ocean alkalinity enhancement (OAE) is a promising negative emission technology that results in the net sequestration of atmospheric carbon. In this paper, we assess the potential impact of OAE on phytoplankton through an analysis of prior studies and the effects of simulated OAE on photosynthetic competence. Our findings suggest that there may be little if any significant impact on most phytoplankton studied to date if OAE is conducted in well-flushed, nearshore environments.
Laura Marín-Samper, Javier Arístegui, Nauzet Hernández-Hernández, and Ulf Riebesell
Biogeosciences, 21, 5707–5724, https://doi.org/10.5194/bg-21-5707-2024, https://doi.org/10.5194/bg-21-5707-2024, 2024
Short summary
Short summary
This study exposed a natural community to two non-CO2-equilibrated ocean alkalinity enhancement (OAE) deployments using different minerals. Adding alkalinity in this manner decreases dissolved CO2, essential for photosynthesis. While photosynthesis was not suppressed, bloom formation was mildly delayed, potentially impacting marine food webs. The study emphasizes the need for further research on OAE without prior equilibration and on its ecological implications.
Riss M. Kell, Rebecca J. Chmiel, Deepa Rao, Dawn M. Moran, Matthew R. McIlvin, Tristan J. Horner, Nicole L. Schanke, Ichiko Sugiyama, Robert B. Dunbar, Giacomo R. DiTullio, and Mak A. Saito
Biogeosciences, 21, 5685–5706, https://doi.org/10.5194/bg-21-5685-2024, https://doi.org/10.5194/bg-21-5685-2024, 2024
Short summary
Short summary
Despite interest in modeling the biogeochemical uptake and cycling of the trace metal zinc (Zn), measurements of Zn uptake in natural marine phytoplankton communities have not been conducted previously. To fill this gap, we employed a stable isotope uptake rate measurement method to quantify Zn uptake into natural phytoplankton assemblages within the Southern Ocean. Zn demand was high and rapid enough to depress the inventory of Zn available to phytoplankton on seasonal timescales.
Luisa Chiara Meiritz, Tim Rixen, Anja Karin van der Plas, Tarron Lamont, and Niko Lahajnar
Biogeosciences, 21, 5261–5276, https://doi.org/10.5194/bg-21-5261-2024, https://doi.org/10.5194/bg-21-5261-2024, 2024
Short summary
Short summary
Moored and drifting sediment trap experiments in the northern (nBUS) and southern (sBUS) Benguela Upwelling System showed that active carbon fluxes by vertically migrating zooplankton were about 3 times higher in the sBUS than in the nBUS. Despite these large variabilities, the mean passive particulate organic carbon (POC) fluxes were almost equal in the two subsystems. The more intense near-bottom oxygen minimum layer seems to lead to higher POC fluxes and accumulation rates in the nBUS.
Michael R. Roman, Andrew H. Altieri, Denise Breitburg, Erica M. Ferrer, Natalya D. Gallo, Shin-ichi Ito, Karin Limburg, Kenneth Rose, Moriaki Yasuhara, and Lisa A. Levin
Biogeosciences, 21, 4975–5004, https://doi.org/10.5194/bg-21-4975-2024, https://doi.org/10.5194/bg-21-4975-2024, 2024
Short summary
Short summary
Oxygen-depleted ocean waters have increased worldwide. In order to improve our understanding of the impacts of this oxygen loss on marine life it is essential that we develop reliable indicators that track the negative impacts of low oxygen. We review various indicators of low-oxygen stress for marine animals including their use, research needs, and application to confront the challenges of ocean oxygen loss.
Charlotte Eich, Mathijs van Manen, J. Scott P. McCain, Loay J. Jabre, Willem H. van de Poll, Jinyoung Jung, Sven B. E. H. Pont, Hung-An Tian, Indah Ardiningsih, Gert-Jan Reichart, Erin M. Bertrand, Corina P. D. Brussaard, and Rob Middag
Biogeosciences, 21, 4637–4663, https://doi.org/10.5194/bg-21-4637-2024, https://doi.org/10.5194/bg-21-4637-2024, 2024
Short summary
Short summary
Phytoplankton growth in the Southern Ocean (SO) is often limited by low iron (Fe) concentrations. Sea surface warming impacts Fe availability and can affect phytoplankton growth. We used shipboard Fe clean incubations to test how changes in Fe and temperature affect SO phytoplankton. Their abundances usually increased with Fe addition and temperature increase, with Fe being the major factor. These findings imply potential shifts in ecosystem structure, impacting food webs and elemental cycling.
Miriam Tivig, David P. Keller, and Andreas Oschlies
Biogeosciences, 21, 4469–4493, https://doi.org/10.5194/bg-21-4469-2024, https://doi.org/10.5194/bg-21-4469-2024, 2024
Short summary
Short summary
Marine biological production is highly dependent on the availability of nitrogen and phosphorus. Rivers are the main source of phosphorus to the oceans but poorly represented in global model oceans. We include dissolved nitrogen and phosphorus from river export in a global model ocean and find that the addition of riverine phosphorus affects marine biology on millennial timescales more than riverine nitrogen alone. Globally, riverine phosphorus input increases primary production rates.
Menghong Dong, Xinyu Guo, Takuya Matsuura, Taichi Tebakari, and Jing Zhang
EGUsphere, https://doi.org/10.5194/egusphere-2024-2581, https://doi.org/10.5194/egusphere-2024-2581, 2024
Short summary
Short summary
Submarine groundwater discharge (SGD), a common coastal hydrological process that involves submarine inflow of groundwater into the sea, is associated with a large nutrient load. To clarify the distribution of SGD-derived nutrients after release at the bottom of the sea and their contribution to phytoplankton growth in the marine ecosystem, we modeled the SGD process in Toyama Bay using a specialized computer code that can distinguish SGD-derived nutrients from nutrients from other sources.
Esdoorn Willcox, Marcos Lemes, Thomas Juul-Pedersen, Mikael Kristian Sejr, Johnna Marchiano Holding, and Søren Rysgaard
Biogeosciences, 21, 4037–4050, https://doi.org/10.5194/bg-21-4037-2024, https://doi.org/10.5194/bg-21-4037-2024, 2024
Short summary
Short summary
In this work, we measured the chemistry of seawater from samples obtained from different depths and locations off the east coast of the Northeast Greenland National Park to determine what is influencing concentrations of dissolved CO2. Historically, the region has always been thought to take up CO2 from the atmosphere, but we show that it is possible for the region to become a source in late summer. We discuss the variables that may be related to such changes.
Vlad A. Macovei, Louise C. V. Rewrie, Rüdiger Röttgers, and Yoana G. Voynova
EGUsphere, https://doi.org/10.5194/egusphere-2024-2643, https://doi.org/10.5194/egusphere-2024-2643, 2024
Short summary
Short summary
A commercial vessel equipped with scientific instruments regularly travelled between two large macro-tidal estuaries. We found that biogeochemical variability in the outer estuaries is driven by the 14-day spring-neap tidal cycle, with strong effects on dissolved inorganic and organic carbon concentrations and distribution. Since this land-sea interface effect increases the strength of the carbon source to the atmosphere by 74 % during spring tide, it should be accounted for in regional models.
Lennart Thomas Bach, Aaron James Ferderer, Julie LaRoche, and Kai Georg Schulz
Biogeosciences, 21, 3665–3676, https://doi.org/10.5194/bg-21-3665-2024, https://doi.org/10.5194/bg-21-3665-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement (OAE) is an emerging marine CO2 removal method, but its environmental effects are insufficiently understood. The OAE Pelagic Impact Intercomparison Project (OAEPIIP) provides funding for a standardized and globally replicated microcosm experiment to study the effects of OAE on plankton communities. Here, we provide a detailed manual for the OAEPIIP experiment. We expect OAEPIIP to help build scientific consensus on the effects of OAE on plankton.
Marlena Szeligowska, Déborah Benkort, Anna Przyborska, Mateusz Moskalik, Bernabé Moreno, Emilia Trudnowska, and Katarzyna Błachowiak-Samołyk
Biogeosciences, 21, 3617–3639, https://doi.org/10.5194/bg-21-3617-2024, https://doi.org/10.5194/bg-21-3617-2024, 2024
Short summary
Short summary
The European Arctic is experiencing rapid regional warming, causing glaciers that terminate in the sea to retreat onto land. Due to this process, the area of a well-studied fjord, Hornsund, has increased by around 100 km2 (40%) since 1976. Combining satellite and in situ data with a mathematical model, we estimated that, despite some negative consequences of glacial meltwater release, such emerging coastal waters could mitigate climate change by increasing carbon uptake and storage by sediments.
Mallory C. Ringham, Nathan Hirtle, Cody Shaw, Xi Lu, Julian Herndon, Brendan R. Carter, and Matthew D. Eisaman
Biogeosciences, 21, 3551–3570, https://doi.org/10.5194/bg-21-3551-2024, https://doi.org/10.5194/bg-21-3551-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement leverages the large surface area and carbon storage capacity of the oceans to store atmospheric CO2 as dissolved bicarbonate. We monitored CO2 uptake in seawater treated with NaOH to establish operational boundaries for carbon removal experiments. Results show that CO2 equilibration occurred on the order of weeks to months, was consistent with values expected from equilibration calculations, and was limited by mineral precipitation at high pH and CaCO3 saturation.
Riel Carlo O. Ingeniero, Gesa Schulz, and Hermann W. Bange
Biogeosciences, 21, 3425–3440, https://doi.org/10.5194/bg-21-3425-2024, https://doi.org/10.5194/bg-21-3425-2024, 2024
Short summary
Short summary
Our research is the first to measure dissolved NO concentrations in temperate estuarine waters, providing insights into its distribution under varying conditions and enhancing our understanding of its production processes. Dissolved NO was supersaturated in the Elbe Estuary, indicating that it is a source of atmospheric NO. The observed distribution of dissolved NO most likely resulted from nitrification.
Celeste López-Abbate, John E. Garzón-Cardona, Ricardo Silva, Juan-Carlos Molinero, Laura A. Ruiz-Etcheverry, Ana M. Martínez, Azul S. Gilabert, and Rubén J. Lara
EGUsphere, https://doi.org/10.5194/egusphere-2024-1860, https://doi.org/10.5194/egusphere-2024-1860, 2024
Short summary
Short summary
This study examines how microbial community structure, growth, and grazing impact the DOM pool in the Patagonian Shelf. Despite higher phytoplankton biomass, faster-growing bacteria were selectively grazed by protists leading to DOM accumulation, likely due to a reduction in DOM-consuming bacteria and the addition of egestion compounds. Experimental data showed that while bacteria remained as the primarily shapers of DOM quality, grazing pressure impacted on DOM accumulation.
Weiyi Tang, Jeff Talbott, Timothy Jones, and Bess B. Ward
Biogeosciences, 21, 3239–3250, https://doi.org/10.5194/bg-21-3239-2024, https://doi.org/10.5194/bg-21-3239-2024, 2024
Short summary
Short summary
Wastewater treatment plants (WWTPs) are known to be hotspots of greenhouse gas emissions. However, the impact of WWTPs on the emission of the greenhouse gas N2O in downstream aquatic environments is less constrained. We found spatially and temporally variable but overall higher N2O concentrations and fluxes in waters downstream of WWTPs, pointing to the need for efficient N2O removal in addition to the treatment of nitrogen in WWTPs.
Daniel Müller, Bo Liu, Walter Geibert, Moritz Holtappels, Lasse Sander, Elda Miramontes, Heidi Taubner, Susann Henkel, Kai-Uwe Hinrichs, Denise Bethke, Ingrid Dohrmann, and Sabine Kasten
EGUsphere, https://doi.org/10.5194/egusphere-2024-1632, https://doi.org/10.5194/egusphere-2024-1632, 2024
Short summary
Short summary
Coastal and shelf sediments are the most important sinks for organic carbon (OC) on Earth. We produced a new high-resolution sediment and pore-water dataset from the Helgoland Mud Area (HMA), North Sea, to determine, which depositional factors control the preservation of OC. The burial efficiency is highest in an area of high sedimentation and terrigenous OC. The HMA covers 0.09 % of the North Sea, but accounts for 0.76 % of its OC accumulation, highlighting the importance of the depocentre.
Deep S. Banerjee and Jozef Skakala
EGUsphere, https://doi.org/10.22541/essoar.171405637.76928549/v1, https://doi.org/10.22541/essoar.171405637.76928549/v1, 2024
Short summary
Short summary
Nitrate is a crucial nutrient in oceans. Excess nutrients can trigger uncontrolled algae growth (eutrophication), damaging marine ecosystems. We used a machine learning tool to generate a skilled, gap-free, bi-decadal surface nitrate dataset from sparse observations. This dataset reveals areas on the North West European Shelf at risk of eutrophication, bi-decadal trends in coastal nitrate, and an impact of winter nitrate on spring phytoplankton blooms.
Amanda Y. L. Cheong, Kogila Vani Annammala, Ee Ling Yong, Yongli Zhou, Robert S. Nichols, and Patrick Martin
Biogeosciences, 21, 2955–2971, https://doi.org/10.5194/bg-21-2955-2024, https://doi.org/10.5194/bg-21-2955-2024, 2024
Short summary
Short summary
We measured nutrients and dissolved organic matter for 1 year in a eutrophic tropical estuary to understand their sources and cycling. Our data show that the dissolved organic matter originates partly from land and partly from microbial processes in the water. Internal recycling is likely important for maintaining high nutrient concentrations, and we found that there is often excess nitrogen compared to silicon and phosphorus. Our data help to explain how eutrophication persists in this system.
Darren Pilcher, Jessica Cross, Natalie Monacci, Linquan Mu, Kelly Kearney, Albert Hermann, and Wei Cheng
EGUsphere, https://doi.org/10.5194/egusphere-2024-1096, https://doi.org/10.5194/egusphere-2024-1096, 2024
Short summary
Short summary
The Bering Sea shelf is a highly productive marine ecosystem that is vulnerable to ocean acidification. We use a computational model to simulate the carbon cycle and acidification rates from 1970–2022. The results suggest that bottom water acidification rates are more than twice as great as surface rates. Bottom waters are also naturally more acidic, thus these waters will pass key thresholds known to negatively impact marine organisms, such as red king crab, much sooner than surface waters.
Aaron Ferderer, Kai G. Schulz, Ulf Riebesell, Kirralee G. Baker, Zanna Chase, and Lennart T. Bach
Biogeosciences, 21, 2777–2794, https://doi.org/10.5194/bg-21-2777-2024, https://doi.org/10.5194/bg-21-2777-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement (OAE) is a promising method of atmospheric carbon removal; however, its ecological impacts remain largely unknown. We assessed the effects of simulated silicate- and calcium-based mineral OAE on diatom silicification. We found that increased silicate concentrations from silicate-based OAE increased diatom silicification. In contrast, the enhancement of alkalinity had no effect on community silicification and minimal effects on the silicification of different genera.
David González-Santana, María Segovia, Melchor González-Dávila, Librada Ramírez, Aridane G. González, Leonardo J. Pozzo-Pirotta, Veronica Arnone, Victor Vázquez, Ulf Riebesell, and J. Magdalena Santana-Casiano
Biogeosciences, 21, 2705–2715, https://doi.org/10.5194/bg-21-2705-2024, https://doi.org/10.5194/bg-21-2705-2024, 2024
Short summary
Short summary
In a recent experiment off the coast of Gran Canaria (Spain), scientists explored a method called ocean alkalinization enhancement (OAE), where carbonate minerals were added to seawater. This process changed the levels of certain ions in the water, affecting its pH and buffering capacity. The researchers were particularly interested in how this could impact the levels of essential trace metals in the water.
Lucas Porz, Wenyan Zhang, Nils Christiansen, Jan Kossack, Ute Daewel, and Corinna Schrum
Biogeosciences, 21, 2547–2570, https://doi.org/10.5194/bg-21-2547-2024, https://doi.org/10.5194/bg-21-2547-2024, 2024
Short summary
Short summary
Seafloor sediments store a large amount of carbon, helping to naturally regulate Earth's climate. If disturbed, some sediment particles can turn into CO2, but this effect is not well understood. Using computer simulations, we found that bottom-contacting fishing gears release about 1 million tons of CO2 per year in the North Sea, one of the most heavily fished regions globally. We show how protecting certain areas could reduce these emissions while also benefitting seafloor-living animals.
Jiaying A. Guo, Robert F. Strzepek, Kerrie M. Swadling, Ashley T. Townsend, and Lennart T. Bach
Biogeosciences, 21, 2335–2354, https://doi.org/10.5194/bg-21-2335-2024, https://doi.org/10.5194/bg-21-2335-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement aims to increase atmospheric CO2 sequestration by adding alkaline materials to the ocean. We assessed the environmental effects of olivine and steel slag powder on coastal plankton. Overall, slag is more efficient than olivine in releasing total alkalinity and, thus, in its ability to sequester CO2. Slag also had less environmental effect on the enclosed plankton communities when considering its higher CO2 removal potential based on this 3-week experiment.
Giovanni Galli, Sarah Wakelin, James Harle, Jason Holt, and Yuri Artioli
Biogeosciences, 21, 2143–2158, https://doi.org/10.5194/bg-21-2143-2024, https://doi.org/10.5194/bg-21-2143-2024, 2024
Short summary
Short summary
This work shows that, under a high-emission scenario, oxygen concentration in deep water of parts of the North Sea and Celtic Sea can become critically low (hypoxia) towards the end of this century. The extent and frequency of hypoxia depends on the intensity of climate change projected by different climate models. This is the result of a complex combination of factors like warming, increase in stratification, changes in the currents and changes in biological processes.
Sandy E. Tenorio and Laura Farías
Biogeosciences, 21, 2029–2050, https://doi.org/10.5194/bg-21-2029-2024, https://doi.org/10.5194/bg-21-2029-2024, 2024
Short summary
Short summary
Time series studies show that CH4 is highly dynamic on the coastal ocean surface and planktonic communities are linked to CH4 accumulation, as found in coastal upwelling off Chile. We have identified the crucial role of picoplankton (> 3 µm) in CH4 recycling, especially with the addition of methylated substrates (trimethylamine and methylphosphonic acid) during upwelling and non-upwelling periods. These insights improve understanding of surface ocean CH4 recycling, aiding CH4 emission estimates.
Charlotte A. J. Williams, Tom Hull, Jan Kaiser, Claire Mahaffey, Naomi Greenwood, Matthew Toberman, and Matthew R. Palmer
Biogeosciences, 21, 1961–1971, https://doi.org/10.5194/bg-21-1961-2024, https://doi.org/10.5194/bg-21-1961-2024, 2024
Short summary
Short summary
Oxygen (O2) is a key indicator of ocean health. The risk of O2 loss in the productive coastal/continental slope regions is increasing. Autonomous underwater vehicles equipped with O2 optodes provide lots of data but have problems resolving strong vertical O2 changes. Here we show how to overcome this and calculate how much O2 is supplied to the low-O2 bottom waters via mixing. Bursts in mixing supply nearly all of the O2 to bottom waters in autumn, stopping them reaching ecologically low levels.
Sabine Schmidt and Ibrahima Iris Diallo
Biogeosciences, 21, 1785–1800, https://doi.org/10.5194/bg-21-1785-2024, https://doi.org/10.5194/bg-21-1785-2024, 2024
Short summary
Short summary
Along the French coast facing the Bay of Biscay, the large Gironde and Loire estuaries suffer from hypoxia. This prompted a study of the small Charente estuary located between them. This work reveals a minimum oxygen zone in the Charente estuary, which extends for about 25 km. Temperature is the main factor controlling the hypoxia. This calls for the monitoring of small turbid macrotidal estuaries that are vulnerable to hypoxia, a risk expected to increase with global warming.
Simone R. Alin, Jan A. Newton, Richard A. Feely, Samantha Siedlecki, and Dana Greeley
Biogeosciences, 21, 1639–1673, https://doi.org/10.5194/bg-21-1639-2024, https://doi.org/10.5194/bg-21-1639-2024, 2024
Short summary
Short summary
We provide a new multi-stressor data product that allows us to characterize the seasonality of temperature, O2, and CO2 in the southern Salish Sea and delivers insights into the impacts of major marine heatwave and precipitation anomalies on regional ocean acidification and hypoxia. We also describe the present-day frequencies of temperature, O2, and ocean acidification conditions that cross thresholds of sensitive regional species that are economically or ecologically important.
Ting Wang, Buyun Du, Inke Forbrich, Jun Zhou, Joshua Polen, Elsie M. Sunderland, Prentiss H. Balcom, Celia Chen, and Daniel Obrist
Biogeosciences, 21, 1461–1476, https://doi.org/10.5194/bg-21-1461-2024, https://doi.org/10.5194/bg-21-1461-2024, 2024
Short summary
Short summary
The strong seasonal increases of Hg in aboveground biomass during the growing season and the lack of changes observed after senescence in this salt marsh ecosystem suggest physiologically controlled Hg uptake pathways. The Hg sources found in marsh aboveground tissues originate from a mix of sources, unlike terrestrial ecosystems, where atmospheric GEM is the main source. Belowground plant tissues mostly take up Hg from soils. Overall, the salt marsh currently serves as a small net Hg sink.
Eleanor Simpson, Debby Ianson, Karen E. Kohfeld, Ana C. Franco, Paul A. Covert, Marty Davelaar, and Yves Perreault
Biogeosciences, 21, 1323–1353, https://doi.org/10.5194/bg-21-1323-2024, https://doi.org/10.5194/bg-21-1323-2024, 2024
Short summary
Short summary
Shellfish aquaculture operates in nearshore areas where data on ocean acidification parameters are limited. We show daily and seasonal variability in pH and saturation states of calcium carbonate at nearshore aquaculture sites in British Columbia, Canada, and determine the contributing drivers of this variability. We find that nearshore locations have greater variability than open waters and that the uptake of carbon by phytoplankton is the major driver of pH and saturation state variability.
S. Alejandra Castillo Cieza, Rachel H. R. Stanley, Pierre Marrec, Diana N. Fontaine, E. Taylor Crockford, Dennis J. McGillicuddy Jr., Arshia Mehta, Susanne Menden-Deuer, Emily E. Peacock, Tatiana A. Rynearson, Zoe O. Sandwith, Weifeng Zhang, and Heidi M. Sosik
Biogeosciences, 21, 1235–1257, https://doi.org/10.5194/bg-21-1235-2024, https://doi.org/10.5194/bg-21-1235-2024, 2024
Short summary
Short summary
The coastal ocean in the northeastern USA provides many services, including fisheries and habitats for threatened species. In summer 2019, a bloom occurred of a large unusual phytoplankton, the diatom Hemiaulus, with nitrogen-fixing symbionts. This led to vast changes in productivity and grazing rates in the ecosystem. This work shows that the emergence of one species can have profound effects on ecosystem function. Such changes may become more prevalent as the ocean warms due to climate change.
Claudine Hauri, Brita Irving, Sam Dupont, Rémi Pagés, Donna D. W. Hauser, and Seth L. Danielson
Biogeosciences, 21, 1135–1159, https://doi.org/10.5194/bg-21-1135-2024, https://doi.org/10.5194/bg-21-1135-2024, 2024
Short summary
Short summary
Arctic marine ecosystems are highly susceptible to impacts of climate change and ocean acidification. We present pH and pCO2 time series (2016–2020) from the Chukchi Ecosystem Observatory and analyze the drivers of the current conditions to get a better understanding of how climate change and ocean acidification could affect the ecological niches of organisms.
William Hiles, Lucy C. Miller, Craig Smeaton, and William E. N. Austin
Biogeosciences, 21, 929–948, https://doi.org/10.5194/bg-21-929-2024, https://doi.org/10.5194/bg-21-929-2024, 2024
Short summary
Short summary
Saltmarsh soils may help to limit the rate of climate change by storing carbon. To understand their impacts, they must be accurately mapped. We use drone data to estimate the size of three saltmarshes in NE Scotland. We find that drone imagery, combined with tidal data, can reliably inform our understanding of saltmarsh size. When compared with previous work using vegetation communities, we find that our most reliable new estimates of stored carbon are 15–20 % smaller than previously estimated.
De'Marcus Robinson, Anh L. D. Pham, David J. Yousavich, Felix Janssen, Frank Wenzhöfer, Eleanor C. Arrington, Kelsey M. Gosselin, Marco Sandoval-Belmar, Matthew Mar, David L. Valentine, Daniele Bianchi, and Tina Treude
Biogeosciences, 21, 773–788, https://doi.org/10.5194/bg-21-773-2024, https://doi.org/10.5194/bg-21-773-2024, 2024
Short summary
Short summary
The present study suggests that high release of ferrous iron from the seafloor of the oxygen-deficient Santa Barabara Basin (California) supports surface primary productivity, creating positive feedback on seafloor iron release by enhancing low-oxygen conditions in the basin.
David J. Yousavich, De'Marcus Robinson, Xuefeng Peng, Sebastian J. E. Krause, Frank Wenzhöfer, Felix Janssen, Na Liu, Jonathan Tarn, Franklin Kinnaman, David L. Valentine, and Tina Treude
Biogeosciences, 21, 789–809, https://doi.org/10.5194/bg-21-789-2024, https://doi.org/10.5194/bg-21-789-2024, 2024
Short summary
Short summary
Declining oxygen (O2) concentrations in coastal oceans can threaten people’s ways of life and food supplies. Here, we investigate how mats of bacteria that proliferate on the seafloor of the Santa Barbara Basin sustain and potentially worsen these O2 depletion events through their unique chemoautotrophic metabolism. Our study shows how changes in seafloor microbiology and geochemistry brought on by declining O2 concentrations can help these mats grow as well as how that growth affects the basin.
Krysten Rutherford, Katja Fennel, Lina Garcia Suarez, and Jasmin G. John
Biogeosciences, 21, 301–314, https://doi.org/10.5194/bg-21-301-2024, https://doi.org/10.5194/bg-21-301-2024, 2024
Short summary
Short summary
We downscaled two mid-century (~2075) ocean model projections to a high-resolution regional ocean model of the northwest North Atlantic (NA) shelf. In one projection, the NA shelf break current practically disappears; in the other it remains almost unchanged. This leads to a wide range of possible future shelf properties. More accurate projections of coastal circulation features would narrow the range of possible outcomes of biogeochemical projections for shelf regions.
Lennart Thomas Bach
Biogeosciences, 21, 261–277, https://doi.org/10.5194/bg-21-261-2024, https://doi.org/10.5194/bg-21-261-2024, 2024
Short summary
Short summary
Ocean alkalinity enhancement (OAE) is a widely considered marine carbon dioxide removal method. OAE aims to accelerate chemical rock weathering, which is a natural process that slowly sequesters atmospheric carbon dioxide. This study shows that the addition of anthropogenic alkalinity via OAE can reduce the natural release of alkalinity and, therefore, reduce the efficiency of OAE for climate mitigation. However, the additionality problem could be mitigated via a variety of activities.
Tsuneo Ono, Daisuke Muraoka, Masahiro Hayashi, Makiko Yorifuji, Akihiro Dazai, Shigeyuki Omoto, Takehiro Tanaka, Tomohiro Okamura, Goh Onitsuka, Kenji Sudo, Masahiko Fujii, Ryuji Hamanoue, and Masahide Wakita
Biogeosciences, 21, 177–199, https://doi.org/10.5194/bg-21-177-2024, https://doi.org/10.5194/bg-21-177-2024, 2024
Short summary
Short summary
We carried out parallel year-round observations of pH and related parameters in five stations around the Japan coast. It was found that short-term acidified situations with Omega_ar less than 1.5 occurred at four of five stations. Most of such short-term acidified events were related to the short-term low salinity event, and the extent of short-term pH drawdown at high freshwater input was positively correlated with the nutrient concentration of the main rivers that flow into the coastal area.
K. Mareike Paul, Martijn Hermans, Sami A. Jokinen, Inda Brinkmann, Helena L. Filipsson, and Tom Jilbert
Biogeosciences, 20, 5003–5028, https://doi.org/10.5194/bg-20-5003-2023, https://doi.org/10.5194/bg-20-5003-2023, 2023
Short summary
Short summary
Seawater naturally contains trace metals such as Mo and U, which accumulate under low oxygen conditions on the seafloor. Previous studies have used sediment Mo and U contents as an archive of changing oxygen concentrations in coastal waters. Here we show that in fjords the use of Mo and U for this purpose may be impaired by additional processes. Our findings have implications for the reliable use of Mo and U to reconstruct oxygen changes in fjords.
Hannah Sharpe, Michel Gosselin, Catherine Lalande, Alexandre Normandeau, Jean-Carlos Montero-Serrano, Khouloud Baccara, Daniel Bourgault, Owen Sherwood, and Audrey Limoges
Biogeosciences, 20, 4981–5001, https://doi.org/10.5194/bg-20-4981-2023, https://doi.org/10.5194/bg-20-4981-2023, 2023
Short summary
Short summary
We studied the impact of submarine canyon processes within the Pointe-des-Monts system on biogenic matter export and phytoplankton assemblages. Using data from three oceanographic moorings, we show that the canyon experienced two low-amplitude sediment remobilization events in 2020–2021 that led to enhanced particle fluxes in the deep-water column layer > 2.6 km offshore. Sinking phytoplankton fluxes were lower near the canyon compared to background values from the lower St. Lawrence Estuary.
Dewi Langlet, Florian Mermillod-Blondin, Noémie Deldicq, Arthur Bauville, Gwendoline Duong, Lara Konecny, Mylène Hugoni, Lionel Denis, and Vincent M. P. Bouchet
Biogeosciences, 20, 4875–4891, https://doi.org/10.5194/bg-20-4875-2023, https://doi.org/10.5194/bg-20-4875-2023, 2023
Short summary
Short summary
Benthic foraminifera are single-cell marine organisms which can move in the sediment column. They were previously reported to horizontally and vertically transport sediment particles, yet the impact of their motion on the dissolved fluxes remains unknown. Using microprofiling, we show here that foraminiferal burrow formation increases the oxygen penetration depth in the sediment, leading to a change in the structure of the prokaryotic community.
Masahiko Fujii, Ryuji Hamanoue, Lawrence Patrick Cases Bernardo, Tsuneo Ono, Akihiro Dazai, Shigeyuki Oomoto, Masahide Wakita, and Takehiro Tanaka
Biogeosciences, 20, 4527–4549, https://doi.org/10.5194/bg-20-4527-2023, https://doi.org/10.5194/bg-20-4527-2023, 2023
Short summary
Short summary
This is the first study of the current and future impacts of climate change on Pacific oyster farming in Japan. Future coastal warming and acidification may affect oyster larvae as a result of longer exposure to lower-pH waters. A prolonged spawning period may harm oyster processing by shortening the shipping period and reducing oyster quality. To minimize impacts on Pacific oyster farming, in addition to mitigation measures, local adaptation measures may be required.
Taketoshi Kodama, Atsushi Nishimoto, Ken-ichi Nakamura, Misato Nakae, Naoki Iguchi, Yosuke Igeta, and Yoichi Kogure
Biogeosciences, 20, 3667–3682, https://doi.org/10.5194/bg-20-3667-2023, https://doi.org/10.5194/bg-20-3667-2023, 2023
Short summary
Short summary
Carbon and nitrogen are essential elements for organisms; their stable isotope ratios (13C : 12C, 15N : 14N) are useful tools for understanding turnover and movement in the ocean. In the Sea of Japan, the environment is rapidly being altered by human activities. The 13C : 12C of small organic particles is increased by active carbon fixation, and phytoplankton growth increases the values. The 15N : 14N variations suggest that nitrates from many sources contribute to organic production.
Cited articles
Aiken, C. M.: Seasonal thermal structure and exchange in Baker Channel, Chile, Dynam. Atmos. Ocean., 58, 1–19, https://doi.org/10.1016/j.dynatmoce.2012.07.001, 2012.
Andrejev, O., Myrberg, K., and Lundberg, P. A.: Age and renewal time of water masses in a semi-enclosed basin – application to the Gulf of Finland, Tellus A, 56, 548–558, https://doi.org/10.3402/tellusa.v56i5.14435, 2004.
Altabet, M. A.: Variations in nitrogen isotopic composition between sinking and suspended particles: implication for nitrogen cycling and particle transformation in the open ocean, Deep-Sea Res., 35, 535–554, 1988.
Andrewartha, H. G. and Birch, L. C.: The ecological web: more on the distribution and abundance of animals, University of Chicago Press, ISBN 0226020347, 9780226020341, 1986.
Barrera, F., Lara, R., and Krock, J.: Factors influencing characteristics and distribution of organic particles and macromolecules in the Pacific-Atlantic connection, J. Mar. Syst., 175, 36–45, https://doi.org/10.1016/j.jmarsys.2017.07.004, 2017.
Batiuk, R. A., Breitburg, D. L., Diaz, R. J., Cronin, T. M., Secor, D. H., and Thursby, G.: Derivation of habitat-specific dissolved oxygen criteria for Chesapeake Bay and its tidal tributaries, J. Exp. Mar. Biol. Ecol., 381, 204–215, https://doi.org/10.1016/j.jembe.2009.07.023, 2009.
Bianchi, T. S.: Biogeochemistry of estuaries. Oxford University Press on Demand, ISBN 0196160827, 9780195160826, 2007.
Bianchi, T. S., DiMarco, S. F., Cowan, J. H., Hetland, R. D., Chapman, P. D., and Allison, J. W.: The science of hypoxia in the Northern Gulf of Mexico: A review, Sci. Total Environ., 408, 1471–1484, https://doi.org/10.1016/j.scitotenv.2009.11.047, 2010.
Billi, M., Mascareño, A., Henríquez, P. A., Rodríguez, I., Padilla, F., and Ruz, G. A.: Learning from crises?, The long and winding road of the salmon industry in Chiloé Island, Chile, Mar. Policy, 140, 105069, https://doi.org/10.1016/j.marpol.2022.105069, 2022.
Breitburg, D. L., Loher, T., Pacey, C. A., and Gerstein, A.: Varying effects of low dissolved oxygen on trophic interactions in an estuarine food web, Ecol. Monogr., 67, 489–507, https://doi.org/10.1890/0012-9615(1997)067[0489:VEOLDO]2.0.CO;2, 1997.
Breitburg, D., Levin, L. A., Oschlies, A., Grégoire, M., Chavez, F. P., Conley, D. J., and Zhang, J.: Declining oxygen in the global ocean and coastal waters, Science, 359, 6371, https://doi.org/10.1126/science.aam7240, 2018.
Castillo, M. I., Cifuentes, U., Pizarro, O., Djurfeldt, L., and Caceres, M.: Seasonal hydrography and surface outflow in a fjord with a deep sill: the Reloncaví fjord, Chile, Ocean Sci., 12, 533–544, https://doi.org/10.5194/os-12-533-2016, 2016.
Carrasco, C. and Silva, N.: Comparación de las características oceanográficas físicas y químicas presente en la zona de Puerto Montt a la boca del Guafo entre el invierno y la primavera de 2004 y entre las primaveras de 1995 y 2004, Cienc. Tecnol. del Mar, 33, 17–44, 2010.
Conley, D. J., Paerl, H. W., Howarth, R. W., Boesch, D. F., Seitzinger, S. P., Havens, K. E., and Likens, G. E.: Controlling eutrophication: nitrogen and phosphorus, Science, 323, 1014–1015, https://doi.org/10.1126/science.1167755, 2009.
Crosswell, J. R., Bravo, F., Pérez-Santos, I., Carlin, G., Cherukuru, N., Schwarger, C., Gregor, R., and Steven, A.: Geophysical controls on metabolic cycling in three Patagonian fjords, Prog. Oceanogr., 207, 102866, https://doi.org/10.1016/j.pocean.2022.102866, 2022.
Davis, J. C.: Minimal dissolved oxygen requirements of aquatic life with emphasis on Canadian species: a review, J. Fish. Board Can., 32, 2295–2332, https://doi.org/10.1139/f75-268, 1975.
Díaz, R. J.: Overview of hypoxia around the world, J. Environ. Qual., 30, 275–281, https://doi.org/10.2134/jeq2001.302275x, 2001.
Diaz, R. J. and Rosenberg, R.: Marine benthic hypoxia: a review of its ecological effects and the behavioural responses of benthic macrofauna, Oceanography and marine biology, Annu. Rev., 33, 245, 1995.
Díaz, P., Pérez-Santos, I., Álvarez, G., Garreaud, R., Pinilla, E., Díaz, M., Sandoval, A., Araya, M., Álvarez, F., Rengel, J., Montero, P., Pizarro, G., López, L., Iriarte, L., Igor, G., and Reguera, B.: Multiscale physical background to an exceptional harmful algal bloom of Dinophysis acuta in a fjord system, Sci. Total Environ., 773, 145621, https://doi.org/10.1016/j.scitotenv.2021.145621, 2021.
Díaz, P. A., Pérez-Santos, I., Basti, L., Garreaud, R., Pinilla, E., Barrera, F., and Figueroa, R. I.: The impact of local and climate change drivers on the formation, dynamics, and potential recurrence of a massive fish-killing microalgal bloom in Patagonian fjord, Sci. Total Environ., 865, 161288, https://doi.org/10.1016/j.scitotenv.2022.161288, 2023.
Ekau, W., Auel, H., Pörtner, H.-O., and Gilbert, D.: Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish), Biogeosciences, 7, 1669–1699, https://doi.org/10.5194/bg-7-1669-2010, 2010.
Fuenzalida, R., Schneider, W., Garcés-Vargas, J., Bravo, L., and Lange, C.: Vertical and horizontal extension of the oxygen minimum zone in the eastern South Pacific Ocean, Deep-Sea Res. Pt. II, 56, 992–1003, https://doi.org/10.1016/j.dsr2.2008.11.001, 2009.
Fry, B. and Sherr, E. B.: δ13C measurements as indicators of carbon flow in marine and freshwater ecosystems, Ecol. Stud., 68, 196–229, https://doi.org/10.1007/978-1-4612-3498-2_12, 1989.
González, H. E., Calderón, M. J., Castro, L., Clement, A., Cuevas, L. A., Daneri, G., and Molinet, C.: Primary production and plankton dynamics in the Reloncaví Fjord and the Interior Sea of Chiloé, Northern Patagonia, Chile, Mar. Ecol. Prog. Ser., 402, 13–30, https://doi.org/10.3354/meps08360, 2010.
González, H. E., Nimptsch, J., Giesecke, R., and Silva, N.: Organic matter distribution, composition and its possible fate in the Chilean North-Patagonian estuarine system, Sci. Total Environ., 657, 1419–1431, https://doi.org/10.1016/j.scitotenv.2018.11.445, 2019.
Grasshoff, K., Ehrhardt, M., and Kremling, K.: Methods of Seawater Analysis, (2nd edition), Verlag Chemie Weinhein, New York, USA, ISBN 3-527-29589-5, 1983.
Grasshoff, K., Kremling, K., and Ehrhardt, M. (Eds.): Methods of seawater analysis, John Wiley and Sons, ISBN 3527613994, 9783527613991, 2009.
Harmelin-Vivien, M., Loizeau, V., Mellon, C., Beker, B., Arlhac, D., Bodiguel, X., Ferraton, T., Hermand, R., Philippon, X., and Salen-Picard, C.: Comparison of C and N stable isotope ratios between surface particulate organic matter and microphytoplankton in the Gulf of lions (NW Mediterranean), Cont. Shelf Res., 28, 1911–1919, https://doi.org/10.1016/j.csr.2008.03.002, 2008.
Holding, J. M., Duarte, C. M., Delgado-Huertas, A., Soetaert, K., Vonk, J. E., Agustí, S., Wassmann, P., and Middelburg, J. J.: Autochthonous and allochthonous contributions of organic carbon to microbial food webs in Svalbard fjords, Limnol. Oceanogr., 62, 1307–1323, https://doi.org/10.1002/lno.10526, 2017.
Guzmán, D. and Silva, N.: Caracterización física y química y masas de agua en los canales australes de Chile entre boca del Guafo y estero Elefantes (crucero CIMAR 4 Fiordos), Cienc. Tecnol. Mar., 25, 45–76, 2002.
IOC, S.: IAPSO: The international thermodynamic equation of seawater–2010: Calculation and use of thermodynamic properties, Intergovernmental Oceanographic Commission, Manuals and Guides No. 56, UNESCO, Manuals and Guides, 56, 1–196, 2010.
Iriarte, J. L.: Natural and human influences on marine processes in Patagonian Subantarctic coastal waters, Front. Mar. Sci., 5, 360, https://doi.org/10.3389/fmars.2018.00360, 2018.
Iriarte, J. L., Gonzalez, H. E., Liu, K. K., Rivas, C., and Valenzuela, C. P.: Spatial and temporal variability of chlorophyll and primary productivity in surface waters of southern Chile, Estuar. Coast. Shelf Sci., 74, 471e480, https://doi.org/10.1016/j.ecss.2007.05.015, 2017.
Jackson, J. M. Johannessen, S., Belluz, J., Hunt, B., and Hannah, C.: Identification of a Seasonal Subsurface Oxygen Minimum in Rivers Inlet, British Columbia, Estuar. Coast., 45, 754–771, https://doi.org/10.1007/s12237-021-00999-y, 2022.
Jackson, J. M., Holmes, K., Klymak, J. M., Bianucci, L., Evans, W., Floyd, W. C., Hannah, C., Hare, A., and Wan, D.: Winter Arctic outflow winds cause upper ocean cooling and reoxygenation in a temperate Canadian fjord, Geophys. Res. Lett., 50, e2023GL104549, https://doi.org/10.1029/2023GL104549, 2023.
Kattner, G. and Becker, H.: Nutrients and organic nitrogenous compounds in the marginal ice zone of the Fram Strait, J. Mar. Syst., 2, 385–394, https://doi.org/10.1016/0924-7963(91)90043-T, 1991.
Kuliński, K., Kędra, M., Legeżyńska, J., Gluchowska, M., and Zaborska, A.: Particulate organic matter sinks and sources in high Arctic fjord, J. Mar. Syst., 139, 27–37, https://doi.org/10.1016/j.jmarsys.2014.04.018, 2014.
Kutty, M. N.: Respiratory quotients in goldfish and rainbow trout, J. Fish. Board Can., 25, 1689–1728, https://doi.org/10.1139/f68-150, 1968.
Laffoley, D. and Baxter, J. M.: Ocean deoxygenation: Everyone's problem-Causes, impacts, consequences and solutions, Gland, Switzerland, IUCN, https://doi.org/10.2305/IUCN.CH.2019.13.en, 2019.
Landaeta, M. F., Gómez, A., Contreras, J. E., Figueroa-González, Y., Pinilla, E., Reche, P., Castillo, M. I., and Plaza, G.: Linking shape and growth in young-of-the-year rock fish: an ecological carry-over effect?, Mar. Biol., 170, 103, https://doi.org/10.1007/s00227-023-04248-7, 2023.
Lefort, S.: A multidisciplinary study of hypoxia in the deep water of the Estuary and Gulf of St. Lawrence: Is this ecosystem on borrowed time?, McGill University (Canada), PhD Thesis Department of Earth and Planetary Sciences McGill University, Montreal, 2012.
Linford, P., Pérez-Santos, I., Montes, I., Dewitte, B., Buchan, S., Narváez, D., Saldías, G., Pinilla, E., Garreaud, R., Díaz, P., Schwertes, C., Montero, P., Rodríguez-Villegas, C., Cáceres-Soto M., Mancilla-Gutiérrez, G., and Altamirano, R.: Recent deoxygenation of Patagonian fjord subsurface waters connected to the Peru–Chile undercurrent and equatorial subsurface water variability, Global Biogeochem. Cy., 37, e2022GB007688, https://doi.org/10.1029/2022GB007688, 2023.
Mannino, A., Russ, M. E., and Hooker, S. B.: Algorithm development and validation for satellite-derived distributions of DOC and CDOM in the U.S. Middle Atlantic Bight, J. Geophys. Res., 113, C07051, https://doi.org/10.1029/2007JC004493, 2008.
Mardones, J. I., Paredes, J., Godoy, M., Suarez, R., Norambuena, L., Vargas, V., Fuenzalida, G., Pinilla, E., Artal, O., Rojas, X., Dorantes-Aranda, J. J., Lee Chang, K. J., Anderson, D. M., and Hallegraeff, G. M.: Disentangling the environmental processes responsible for the world's largest farmed fish-killing harmful algal bloom: Chile, 2016, Sci. Total Environ., 766, 144383, https://doi.org/10.1016/j, 2021.
Martínez, D., De Lázaro, O., Cortés, P., Oyarzún-Salazar, R., Paschke, K., and Vargas-Chacoff, L.: Hypoxia modulates the transcriptional immunological response in Oncorhynchus kisutch, Fish Shellf. Immun., 106, 1042–1051, https://doi.org/10.1016/j.fsi.2020.09.025, 2020.
Meire, L., Soetaert, K. E. R., and Meysman, F. J. R.: Impact of global change on coastal oxygen dynamics and risk of hypoxia, Biogeosciences, 10, 2633–2653, https://doi.org/10.5194/bg-10-2633-2013, 2013.
Monsen, N. E., Cloern, J. E., Lucas, L. V., and Monismith, S. G.: A comment on the use of flushing time, residence time, and age as transport time scales, Limnol. Oceanogr., 47, 1545–1553, https://doi.org/10.4319/lo.2002.47.5.1545, 2002.
Montero, P., Daneri, G., Gonzalez, H. E., Iriarte, J. L., Tapia, F. J., Lizarraga, L., and Pizarro, O.: Seasonal variability of primary production in a fjord ecosystem of the Chilean Patagonia: Implications for the transfer of carbon within pelagic food webs, Cont. Shelf Res., 31, 202–215, https://doi.org/10.1016/j.csr.2010.09.003, 2011.
Montero, P., Pérez-Santos, I., Daneri, G., Gutiérrez, M. H., Igor, G., Seguel, R., and Crawford, D. W.: A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem, Estuarine, Coast. Shelf Sci., 199, 105–116, https://doi.org/10.3856/vol45-issue5-fulltext-16, 2017a.
Montero, P., Daneri, G., Tapia, F., Iriarte, J. L., and Crawford, D.: Diatom blooms and primary production in a channel ecosystem of central Patagonia, Lat. Am. J. Aquat. Res., 45, 999–1016, https://doi.org/10.3856/vol45-issue5-fulltext-16, 2017b.
Montero, P., Gutiérrez, M. H., Daneri, G., and Jacob, B.: The Effect of Salmon Food-Derived DOM and Glacial Melting on Activity and Diversity of Free-Living Bacterioplankton in Chilean Patagonian Fjords, Front. Microbiol., 12, 772900, https://doi.org/10.3389/fmicb.2021.772900, 2022.
Nechad, B., Dogliotti, A., Ruddick, K., and Doxaran, D.: Particulate backscattering and suspended matter concentration retrieval from remote-sensed turbidity in various coastal and riverine turbidy waters, Submitted for the Proceedings of ESA Living Planet Symposium, Prague, 9–13 May 2016, ESA-SP 740, 2016.
Nimptsch, J., Woelfl, S., Osorio, S., Valenzuela, J., Ebersbach, P., von Tuempling, W., and Graeber, D.: Tracing dissolved organic matter (DOM) from land-based aquaculture systems in North Patagonian streams, Sci. Total Environ., 537, 129–138, https://doi.org/10.1016/j.scitotenv.2015.07.160, 2015.
Oschlies, A., Brandt, P., Stramma, L., and Schmidtko, S.: Drivers and mechanisms of ocean deoxygenation, Nat. Geosci., 11, 467–473, https://doi.org/10.1038/s41561-018-0152-1, 2018.
Paulmier, A. and Ruiz-Pino, D.: Oxygen minimum zones (OMZs) in the modern ocean, Prog. Oceanogr., 80, 113–128, https://doi.org/10.1016/j.pocean.2008.08.001, 2009.
Pawlowicz, R., Beardsley, B., and Lentz, S.: Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE, Comput. Geosci., 28, 929–937, https://doi.org/10.1016/S0098-3004(02)00013-4, 2002.
Pérez-Santos, I., Garcés-Vargas, J., Schneider, W., Ross, L., Parra, S., and Valle-Levinson, A.: Double-diffusive layering and mixing in Patagonian fjords, Prog. Oceanogr., 129, 35–49, https://doi.org/10.1016/j.pocean.2014.03.012, 2014.
Pérez-Santos, I., Castro, L., Ross, L., Niklitschek, E., Mayorga, N., Cubillos, L., Gutierrez, M., Escalona, E., Castillo, M., Alegría, N., and Daneri, G.: Turbulence and hypoxia contribute to dense biological scattering layers in a Patagonian fjord system, Ocean Sci., 14, 1185–1206, https://doi.org/10.5194/os-14-1185-2018, 2018.
Pérez-Santos, I., Seguel, R., Schneider, W., Linford, P., Donoso, D., Navarro, E., Amaya-Cárcamo, C., Pinilla, E., and Daneri, G.: Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean, Ocean Sci., 15, 1247–1266, https://doi.org/10.5194/os-15-1247-2019, 2019.
Pérez-Santos, I., Díaz, P., Silva, N., Garreaud, R., Montero, P., Henríquez-Castillo, C., Barrera, F., Linford, P., Amaya, C., Contreras, S., Aracena, C., Pinilla, E., Altamirano, R., Vallejos, L., Pavez, J., and Maulen, J.: Oceanography time series reveals annual asynchrony input between oceanic and estuarine waters in Patagonian fjords, Sci. Total Environ., 798, 149241, https://doi.org/10.1016/j.scitotenv.2021.149241, 2021.
Pinilla, E., Castillo, M. I., Pérez-Santos, I., Venegas, O., and Valle-Levinson, A.: Water age variability in a Patagonian fjord, J. Mar. Syst., 210, 103376, https://doi.org/10.1016/j.jmarsys.2020.103376, 2020.
Prandle, D.: Simple theory for designing tidal power schemes, Adv. Water Res., 7, 21–27, https://doi.org/10.1016/0309-1708(84)90026-5, 1984.
Quiñones, R. A., Fuentes, M., Montes, R. M., Soto, D., and León-Muñoz, J.: Environmental issues in Chilean salmon farming: a review, Rev. Aquacult., 11, 375–402, https://doi.org/10.1111/raq.12337, 2019.
Rabalais, N. N., Díaz, R. J., Levin, L. A., Turner, R. E., Gilbert, D., and Zhang, J.: Dynamics and distribution of natural and human-caused hypoxia, Biogeosciences, 7, 585–619, https://doi.org/10.5194/bg-7-585-2010, 2010.
Remeikaitė-Nikienė, N., Lujanienė, G., Malejevas, V., Barisevičiūtė, R., Zilius, M., Vybernaitė-Lubienė, I., and Stankevičius, A.: Assessing nature and dynamics of POM in transitional environment (the Curonian Lagoon, SE Baltic Sea) using a stable isotope approach, Ecol. Indicat., 82, 217–226, https://doi.org/10.1016/j.ecolind.2017.06.035, 2017.
Reche, P., Artal, O., Pinilla, E., Ruiz, C., Venegas, O., Arriagada, A., and Falvey, M.: CHONOS: oceanographic information website for Chilean Patagonia, Ocean Coast Manag., 208, 105634, https://doi.org/10.1016/j.ocecoaman.2021.105634, 2021.
Redfield, A. C.: The biological control of chemical factors in the environment, Am. Sci., 46, 230–221, 1958.
Robinson, C.: Microbial respiration, the engine of ocean deoxygenation, Front. Mar. Sci., 5, 533, https://doi.org/10.3389/fmars.2018.00533, 2019.
Rosentreter, J., Laruelle, G., Bange, H., Bianchi, T., Busecke, J., Cai, W., Eyre, B., Forbrich, I., Kwon, E., Maavara, T., Moosdorf, N., Najjar, R., Sarma, V., Van Dam, B., and Regnier, P.: Coastal vegetation and estuaries are collectively a greenhouse gas sink, Nat. Clim. Change, 13, 579–587, https://doi.org/10.1038/s41558-023-01682-9, 2023.
Rosen, S., Bianucci, L., Jackson, J. M., Hare, A., Greengrove, C., Monks, R., Bartlett, M., and Dick, J.: Seasonal near-surface hypoxia in a temperate fjord in Clayoquot Sound, British Columbia, Front. Mar. Sci., 9, 1000041, https://doi.org/10.3389/fmars.2022.1000041, 2022.
Ruiz, C., Artal, O., Pinilla, E., and Sepúlveda, H. H.: Stratification and mixing in the Chilean Inland Sea using an operational model, Ocean Modell., 158, 101750, https://doi.org/10.1016/j.ocemod.2020.101750, 2021.
Sampaio, E., Santos, C., Rosa, I. C., Ferreira, V., Pörtner, H. O., Duarte, C. M., and Rosa, R.: Impacts of hypoxic events surpass those of future ocean warming and acidification, Nat. Ecol. Evol., 5, 311–321, https://doi.org/10.1038/s41559-020-01370-3, 2021.
Saino, T. and Hattori, A.: 15N natural abundance in oceanic suspended particulate matter, Nature, 283, 752–754, 1980.
Saino, T. and Hattori, A.: Geographical variation of the water column distribution of suspended particulate nitrogen and its 15N natural abundance in the Pacific and its marginal seas, Deep-Sea Res., 34, 807–827, 1987.
Savoye, N., Aminot, A., Treguer, P., Fontugne, M., Naulet, N., and Kérouel, R.: Dynamics of particulate organic matter δ15N and δ13C during spring phytoplankton blooms in a macrotidal ecosystem (Bay of Seine, France), Mar. Ecol. Prog. Ser., 255, 27–41, 2003.
Schmidtko, S., Stramma, L., and Visbeck, M.: Decline in global oceanic oxygen content during the past five decades, Nature, 542, 335–339, https://doi.org/10.1038/nature21399, 2017.
Schneider, W., Pérez-Santos, I., Ross, L., Bravo, L., Seguel, R., and Hernández, F.: On the hydrography of Puyuhuapi Channel, Chilean Patagonia, Prog. Oceanogr., 129, 8–18, https://doi.org/10.1016/j.pocean.2014.03.007, 2014.
Schneider, B., Schlitzer, R., Fischer, G., and Nothig, E. M.: Depth-dependent elemental compositions of particulate organic matter (POM) in the ocean, Glob. Biogeochem. Cy., 17, 1032, https://doi.org/10.1029/2002gb001871, 2003.
Sibson, R. and Thomson, G. D.: A seamed quadratic element for contouring, Comput. J., 24, 378–382, https://doi.org/10.1093/comjnl/24.4.378, 1981.
Sievers, H. A.: Temperature and salinity in the austral Chilean channels and fjords, Progress in the oceanographic knowledge of Chilean interior waters, from Puerto Montt to Cape Horn, Comité Oceanográfico Nacional-Pontificia Universidad Católica de Valparaíso, Valparaíso, 31–36, 2008.
Sievers, A. H. and Silva, N.: Water masses and circulation in austral Chilean channels and fjords, in: Progress in the oceanographic knowledge of Chilean inner waters, from Puerto Montt to Cape Horn, edited by: Silva, N. and Palma, S., Comité Oceanografico Nacional, Pontificia Universidad Católica de Valparaíso, Valparaíso, 53–58, http://www.cona.cl/ (last access: September 2022), 2008.
Silva, N.: Physical and chemical characteristics of the surface sediments in the austral Chilean channels and fjords, Progress in the oceanographic knowledge of Chilean interior waters, from Puerto Montt to Cape Horn, 69–75, http://www.cona.mil.cl/ (last access: September 2022), 2008.
Silva, N. and Vargas, C. A.: Hypoxia in Chilean patagonian fjords, Prog. Oceanogr., 129, 62–74, https://doi.org/10.1016/j.pocean.2014.05.016, 2014.
Silva, N., Rojas, N., and Fedele, A.: Water masses in the Humboldt Current System: Properties, distribution, and the nitrate deficit as a chemical water mass tracer for Equatorial Subsurface Water off Chile, Deep-Sea Res. Pt. II, 56, 1004–1020, https://doi.org/10.1016/j.dsr2.2008.12.013, 2009.
Smith, D. C. and Azam, F.: A simple, economical method for measuring bacterial protein synthesis rates in seawater using 3H-leucine, Mar. Microb. Food Webs, 6, 107–114, 1992.
Sibson, R.: A Brief Description of Natural Neighbor Interpolation, edited by: Barnett, V., Interpreting Multivariate Data, John Wiley & Sons, New York, 21–36, 1981.
Soto, D. and Norambuena, F.: Evaluation of salmon farming effects on marine systems in the inner seas of southern Chile: a large-scale mensurative experiment, J. Appl. Ichthyol., 20, 493–501, https://doi.org/10.1111/j.1439-0426.2004.00602, 2004.
Soto, D., León-Muñoz, J., Garreaud, R., Quiñones, R. A., and Morey, F.: Scientific warnings could help to reduce farmed salmon mortality due to harmful algal blooms, Mar. Pol., 132, 104705, https://doi.org/10.1016/j.marpol.2021.104705, 2021.
Soto-Riquelme, C., Pinilla, E., and Ross, L.: Wind influence on residual circulation in Patagonian channels and fjords, Cont. Shelf Res., 254, 104905, https://doi.org/10.1016/j.csr.2022.104905, 2023.
Skamarock, W. C., Klemp, J. B., Dudhia, J., Gill, D. O., Barker, D. M., Duda, M. G., Huang, X.-Y., Wang, W., and Powers, J. G.: A description of the advanced research WRF version 3, NCAR Technical Note, 475, 125, https://doi.org/10.5065/D68S4MVH, 2008.
Smagorinsky, J.: General circulation experiments with the primitive equations, Mon. Weather Rev., 91, 99–164, 1963.
Stanton, B. R.: Some oceanographic observations in the New Zealand fjords, Estuar. Coast. Shelf Sci., 19, 89–104, https://doi.org/10.1016/0272-7714(84)90054-4, 1984.
Stedmon, C. and Norman, N.: Chapter 10 – The Optical Properties of DOM in the Ocean, edited by: Hansell, D. A. and Carlson, C. A., Biogeochemistry of Marine Dissolved Organic Matter (Second Edition), Academic Press, 481–508, ISBN 9780124059405, https://doi.org/10.1016/B978-0-12-405940-5.00010-8, 2015.
Strickland, J. D. H.: Measuring the production of marine phytoplankton, published by the fisheries research board of canada under the control of the honourable the minister of fisheries, 122, 1960.
Strickland, J. D. H. and Parsons, T. E.: Determination of dissolved oxygen, A practical handbook of seawater analysis, 167, 71–75, 1968.
Takeoka, H.: Fundamental concepts of exchange and transport time scales in a coastal sea, Cont. Shelf Res., 3, 311–326, https://doi.org/10.1016/0278-4343(84)90014-1, 1984.
Taucher, J., Boxhammer, T., Bach, L. T., Paul, A. J., Schartau, M., Stange, P., and Riebesell, U.: Changing carbon-to-nitrogen ratios of organic-matter export under ocean acidification, Nat. Clim. Change, 11, 52–57, https://doi.org/10.1038/s41558-020-00915-5, 2020.
Tomas, C. R. (Ed.).: Identifying marine phytoplankton, Elsevier, ISBN 0080534422, 9780080534428, 1997.
Tomas, H., Ittekkot, V., Osterroht, C., and Schneider, B.: Preferential recycling of nutrients – the ocean's way to increase new production and to pass nutrient limitation?, Limnol. Oceanogr., 44, 1999–2004, 1999.
Thomson, R. E. and Emery, W. J.: Data Analysis Methods in Physical Oceanography, Elsevier, Waltham, Mass., ISBN 9780123877826, 2014.
Thomson, R. E., Spear, D. J., Krassovski, M. V., Hourston, R. A. S., Juhász, T. A., and Mihály, S. F.: Buoyancy-driven coastal current blocks ventilation of an anoxic fjord on the Pacific coast of Canada, J. Geophys. Res.-Oceans, 122, 2976–2998, https://doi.org/10.1002/2016JC012512, 2017.
Torres, R., Pantoja, S., Harada, N., González, H. E., Daneri, G., Frangopulos, M., and Fukasawa, M.: Air-sea CO2 fluxes along the coast of Chile: From CO2 outgassing in central northern upwelling waters to CO2 uptake in southern Patagonian fjords, J. Geophys. Res.-Oceans, 116, C09006, https://doi.org/10.1029/2010JC006344, 2011.
Troupin, C., Machín F., Ouberdous M., Sirjacobs D., Barth A., and Becker J.-M.: High-resolution climatology of the northeast Atlantic using Data-Interpolating Variational Analysis (Diva), J. Geophys. Res., 115, C08005, https://doi.org/10.1029/2009JC005512, 2010.
Utermöhl, H.: Zur vervollkommnung der quantitativen phytoplankton-methodik: Mit 1 Tabelle und 15 abbildungen im Text und auf 1 Tafel, Internationale Vereinigung für theoretische und angewandte Limnologie: Mitteilungen, 9, 1–38, https://doi.org/10.1018/05384680.1958.11904091, 1958.
Vanhellemont, Q. and Ruddick, K.: Atmospheric correction of metre-scale optical satellite data for inland and coastal water applications, Remote Sens. Environ., 216, 586–597, https://doi.org/10.1016/j.rse.2018.07.015, 2018.
Vaquer-Sunyer, R., and Duarte, C. M.: Thresholds of hypoxia for marine biodiversity, P. Natl. Acad. Sci. USAs, 105, 15452–15457, https://doi.org/10.1073/pnas.0803833105, 2008.
Valdenegro, A., and Silva, N.: Caracterizacion oceanografica física y química de la zona de canales y fiordos australes de Chile entre el estrecho de Magallanes y cabo de Hornos (CIMAR 3 fiordo), Cienc. Tecnol. del Mar, 26, 19–60, 2003.
Verardo, D. J., Froelich, P. N., and McIntyre, A.: Determination of organic carbon and nitrogen in marine sediments using the Carlo Erba NA-1500 Analyzer, Deep Sea Res., 37, 157–165, https://doi.org/10.1016/0198-0149(90)90034-S, 1990.
Velinsky, D. J. and Fogel, M. L.: Cycling of dissolved and particulate nitrogen and carbon in the Framvaren Fjord, Norway: stable isotopic variations, Mar. Chem., 67, 161–180, https://doi.org/10.1016/s0304-4203(99)00057-2, 1999.
Wang, X., Olsen, L. M., Reitan, K. I., and Olsen, Y.: Discharge of nutrient wastes from salmon farms: environmental effects, and potential for integrated multi-trophic aquaculture, Aquacult. Env. Interac., 2, 267–283, https://doi.org/10.3354/aei00044, 2012.
Williams, P. I. and Robertson, J. E.: Overall planktonic oxygen and carbon dioxide metabolisms: the problem of reconciling observations and calculations of photosynthetic quotients, J. Plankton Res., 13, 153–169, https://doi.org/10.1093/oxfordjournals.plankt.a042366, 1991.
Yao, W. and Millero, F. J.: The chemistry of the anoxic waters in the Framvaren Fjord, Norway, Aquat. Geochem., 1, 53–88, 1995.
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
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.
The Patagonian fjords comprise a world region where low-oxygen water and hypoxia conditions are...
Altmetrics
Final-revised paper
Preprint