Articles | Volume 18, issue 20
Biogeosciences, 18, 5595–5607, 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue: Biogeochemistry in the BGC-Argo era: from process studies...
Research article 18 Oct 2021
Research article | 18 Oct 2021
Grazing behavior and winter phytoplankton accumulation
Mara Freilich et al.
No articles found.
Philippe Massicotte, Rainer M. W. Amon, David Antoine, Philippe Archambault, Sergio Balzano, Simon Bélanger, Ronald Benner, Dominique Boeuf, Annick Bricaud, Flavienne Bruyant, Gwenaëlle Chaillou, Malik Chami, Bruno Charrière, Jing Chen, Hervé Claustre, Pierre Coupel, Nicole Delsaut, David Doxaran, Jens Ehn, Cédric Fichot, Marie-Hélène Forget, Pingqing Fu, Jonathan Gagnon, Nicole Garcia, Beat Gasser, Jean-François Ghiglione, Gaby Gorsky, Michel Gosselin, Priscillia Gourvil, Yves Gratton, Pascal Guillot, Hermann J. Heipieper, Serge Heussner, Stanford B. Hooker, Yannick Huot, Christian Jeanthon, Wade Jeffrey, Fabien Joux, Kimitaka Kawamura, Bruno Lansard, Edouard Leymarie, Heike Link, Connie Lovejoy, Claudie Marec, Dominique Marie, Johannie Martin, Jacobo Martín, Guillaume Massé, Atsushi Matsuoka, Vanessa McKague, Alexandre Mignot, William L. Miller, Juan-Carlos Miquel, Alfonso Mucci, Kaori Ono, Eva Ortega-Retuerta, Christos Panagiotopoulos, Tim Papakyriakou, Marc Picheral, Louis Prieur, Patrick Raimbault, Joséphine Ras, Rick A. Reynolds, André Rochon, Jean-François Rontani, Catherine Schmechtig, Sabine Schmidt, Richard Sempéré, Yuan Shen, Guisheng Song, Dariusz Stramski, Eri Tachibana, Alexandre Thirouard, Imma Tolosa, Jean-Éric Tremblay, Mickael Vaïtilingom, Daniel Vaulot, Frédéric Vaultier, John K. Volkman, Huixiang Xie, Guangming Zheng, and Marcel Babin
Earth Syst. Sci. Data, 13, 1561–1592,Short summary
The MALINA oceanographic expedition was conducted in the Mackenzie River and the Beaufort Sea systems. The sampling was performed across seven shelf–basin transects to capture the meridional gradient between the estuary and the open ocean. The main goal of this research program was to better understand how processes such as primary production are influencing the fate of organic matter originating from the surrounding terrestrial landscape during its transition toward the Arctic Ocean.
Alexandre Mignot, Hervé Claustre, Gianpiero Cossarini, Fabrizio D'Ortenzio, Elodie Gutknecht, Julien Lamouroux, Paolo Lazzari, Coralie Perruche, Stefano Salon, Raphaelle Sauzède, Vincent Taillandier, and Anna Terruzzi
Preprint under review for BG
Marie Barbieux, Julia Uitz, Bernard Gentili, Orens Pasqueron de Fommervault, Alexandre Mignot, Antoine Poteau, Catherine Schmechtig, Vincent Taillandier, Edouard Leymarie, Christophe Penkerc'h, Fabrizio D'Ortenzio, Hervé Claustre, and Annick Bricaud
Biogeosciences, 16, 1321–1342,Short summary
As commonly observed in oligotrophic stratified waters, a subsurface (or deep) chlorophyll maximum (SCM) frequently characterizes the vertical distribution of phytoplankton chlorophyll in the Mediterranean Sea. SCMs often result from photoacclimation of the phytoplankton organisms. However they can also result from an actual increase in phytoplankton carbon biomass. Our results also suggest that a variety of intermediate types of SCMs are encountered between these two endmember situations.
Alexandre Mignot, Raffaele Ferrari, and Kjell Arne Mork
Biogeosciences, 13, 3485–3502,Short summary
We investigated the bloom onset in the Nordic Seas using 6 bio-optical floats. We found that the float data are consistent with two possible scenarios for the onset of blooms in the Nordic Seas. The Nordic Seas blooms could have started either when the light became sufficiently abundant that the division rates exceeded the loss rates, or when the photoperiod, the number of daily light hours experienced by phytoplankton, exceeded a critical value.
Related subject area
Biogeophysics: Physical - Biological CouplingImpact of moderately energetic fine-scale dynamics on the phytoplankton community structure in the western Mediterranean SeaSeasonal ecosystem vulnerability to climatic anomalies in the MediterraneanEpisodic subduction patches in the western North Pacific identified from BGC-Argo float dataDo Loop Current eddies stimulate productivity in the Gulf of Mexico?Using an oceanographic model to investigate the mystery of the missing puerulusClimate pathways behind phytoplankton-induced atmospheric warmingQuasi-tropical cyclone caused anomalous autumn coccolithophore bloom in the Black SeaDivergent climate feedbacks on winter wheat growing and dormancy periods as affected by sowing date in the North China PlainMicroclimatic comparison of lichen heaths and shrubs: shrubification generates atmospheric heating but subsurface cooling during the growing seasonFire and vegetation dynamics in northwest Siberia during the last 60 years based on high-resolution remote sensingEvidence of eddy-related deep-ocean current variability in the northeast tropical Pacific Ocean induced by remote gap windsRoot uptake under mismatched distributions of water and nutrients in the root zoneInteractive impacts of meteorological and hydrological conditions on the physical and biogeochemical structure of a coastal systemProtists and collembolans alter microbial community composition, C dynamics and soil aggregation in simplified consumer–prey systemsAbundance and viability of particle-attached and free-floating bacteria in dusty and nondusty airLinking tundra vegetation, snow, soil temperature, and permafrostDrivers of the spatial phytoplankton gradient in estuarine–coastal systems: generic implications of a case study in a Dutch tidal bayBiological and biogeochemical methods for estimating bioirrigation: a case study in the Oosterschelde estuaryDissolved inorganic nitrogen and particulate organic nitrogen budget in the Yucatán shelf: driving mechanisms through a physical–biogeochemical coupled modelBasal thermal regime affects the biogeochemistry of subglacial systemsInfluence of oceanic conditions in the energy transfer efficiency estimation of a micronekton modelModulation of the North Atlantic deoxygenation by the slowdown of the nutrient streamStand age and species composition effects on surface albedo in a mixedwood boreal forestAssessing the peatland hummock–hollow classification framework using high-resolution elevation models: implications for appropriate complexity ecosystem modelingTidal and seasonal forcing of dissolved nutrient fluxes in reef communitiesIdeas and perspectives: Development of nascent autotrophic carbon fixation systems in various redox conditions of the fluid degassing on early EarthVertical distribution of chlorophyll in dynamically distinct regions of the southern Bay of BengalRemote and local drivers of oxygen and nitrate variability in the shallow oxygen minimum zone off Mauritania in June 2014Longitudinal contrast in turbulence along a ∼ 19° S section in the Pacific and its consequences for biogeochemical fluxesIdeas and perspectives: Strengthening the biogeosciences in environmental research networksImprint of Southern Ocean mesoscale eddies on chlorophyllGrazing increases litter decomposition rate but decreases nitrogen release rate in an alpine meadowLarge- to submesoscale surface circulation and its implications on biogeochemical/biological horizontal distributions during the OUTPACE cruise (southwest Pacific)OUTPACE long duration stations: physical variability, context of biogeochemical sampling, and evaluation of sampling strategyReviews and syntheses: on the roles trees play in building and plumbing the critical zoneEffects of shrub and tree cover increase on the near-surface atmosphere in northern FennoscandiaMorphological plasticity of root growth under mild water stress increases water use efficiency without reducing yield in maizeAmplification of global warming through pH dependence of DMS production simulated with a fully coupled Earth system modelPhysical control of interannual variations of the winter chlorophyll bloom in the northern Arabian SeaTree growth and its climate signal along latitudinal and altitudinal gradients: comparison of tree rings between Finland and the Tibetan PlateauBiogeochemical versus ecological consequences of modeled ocean physicsAnalytical solution of the nitracline with the evolution of subsurface chlorophyll maximum in stratified water columnsUpwelling and isolation in oxygen-depleted anticyclonic modewater eddies and implications for nitrate cyclingPositive Indian Ocean Dipole events prevent anoxia off the west coast of IndiaLinking diverse nutrient patterns to different water masses within anticyclonic eddies in the upwelling system off PeruCan terrestrial laser scanners (TLSs) and hemispherical photographs predict tropical dry forest succession with liana abundance?Multi-frequency electrical impedance tomography as a non-invasive tool to characterize and monitor crop root systemsThe growth of shrubs on high Arctic tundra at Bylot Island: impact on snow physical properties and permafrost thermal regimeCharacterization of “dead-zone” eddies in the eastern tropical North AtlanticLinking the distribution of microbial deposits from the Great Salt Lake (Utah, USA) to tectonic and climatic processes
Roxane Tzortzis, Andrea M. Doglioli, Stéphanie Barrillon, Anne A. Petrenko, Francesco d'Ovidio, Lloyd Izard, Melilotus Thyssen, Ananda Pascual, Bàrbara Barceló-Llull, Frédéric Cyr, Marc Tedetti, Nagib Bhairy, Pierre Garreau, Franck Dumas, and Gérald Gregori
Biogeosciences, 18, 6455–6477,Short summary
This work analyzes an original high-resolution data set collected in the Mediterranean Sea. The major result is the impact of a fine-scale frontal structure on the distribution of phytoplankton groups, in an area of moderate energy with oligotrophic conditions. Our results provide an in situ confirmation of the findings obtained by previous modeling studies and remote sensing about the structuring effect of the fine-scale ocean dynamics on the structure of the phytoplankton community.
Johannes Vogel, Eva Paton, and Valentin Aich
Biogeosciences, 18, 5903–5927,Short summary
This study investigates extreme ecosystem impacts evoked by temperature and soil moisture in the Mediterranean Basin for the time span 1999–2019 with a specific focus on seasonal variations. The analysis showed that ecosystem vulnerability is caused by several varying combinations of both drivers during the yearly cycle. The approach presented here helps to provide insights on the specific phenological stage of the year in which ecosystem vulnerability to a certain climatic condition occurs.
Shuangling Chen, Mark L. Wells, Rui Xin Huang, Huijie Xue, Jingyuan Xi, and Fei Chai
Biogeosciences, 18, 5539–5554,Short summary
Subduction transports surface waters to the oceanic interior, which can supply significant amounts of carbon and oxygen to the twilight zone. Using a novel BGC-Argo dataset covering the western North Pacific, we successfully identified the imprints of episodic shallow subduction patches. These subduction patches were observed mainly in spring and summer (70.6 %), and roughly half of them extended below ~ 450 m, injecting carbon- and oxygen-enriched waters into the ocean interior.
Pierre Damien, Julio Sheinbaum, Orens Pasqueron de Fommervault, Julien Jouanno, Lorena Linacre, and Olaf Duteil
Biogeosciences, 18, 4281–4303,Short summary
The Gulf of Mexico deep waters are relatively poor in phytoplankton biomass due to low levels of nutrients in the upper layers. Using modeling techniques, we find that the long-living anticyclonic Loop Current eddies that are shed episodically from the Yucatan Channel strongly shape the distribution of phytoplankton and, more importantly, stimulate their growth. This results from the contribution of multiple mechanisms of physical–biogeochemical interactions discussed in this study.
Jessica Kolbusz, Tim Langlois, Charitha Pattiaratchi, and Simon de Lestang
Revised manuscript accepted for BGShort summary
Western rock lobster larvae spend up to 11 months in offshore waters before ocean currents and their ability to swim, transport them back to the coast. In 2008, there was reduction in the number of puerulus (larvae) settling into the fishery. We use an oceanographic model to see how the environment may have contributed to the reduction. Our results show that a combination of effects from local currents and wide-spread “quiet” period in the ocean off WA likely lead to less puerulus settlement.
Rémy Asselot, Frank Lunkeit, Philip B. Holden, and Inga Hense
Revised manuscript accepted for BGShort summary
Previous studies show that phytoplankton light absorption can warm the atmosphere via an increase in air-sea heat exchange and CO2 flux. Which of this flux is the main driver in the phytoplankton-induced atmospheric warming is still unknown. To shed light on this research question, we conduct simulations with a climate model of intermediate complexity. We show that phytoplankton mainly warms the atmosphere by increasing the air-sea CO2 flux.
Sergey V. Stanichny, Elena A. Kubryakova, and Arseny A. Kubryakov
Biogeosciences, 18, 3173–3188,Short summary
In this paper, we show that the short-term impact of tropical cyclones can trigger the intense, long-term bloom of coccolithophores, which are major marine calcifiers playing an important role in the balance and fluxes of inorganic carbon in the ocean. In our paper, we describe the evolution of and physical reasons for such an unusual bloom observed in autumn 2005 in the Black Sea on the basis of satellite data.
Fengshan Liu, Ying Chen, Nini Bai, Dengpan Xiao, Huizi Bai, Fulu Tao, and Quansheng Ge
Biogeosciences, 18, 2275–2287,Short summary
The sowing date is key to the surface biophysical processes in the winter dormancy period. The climate effect of the sowing date shift is therefore very interesting and may contribute to the mitigation of climate change. An earlier sowing date always had a higher LAI but a higher temperature in the dormancy period and a lower temperature in the growth period. The main reason was the relative contributions of the surface albedo and energy partitioning processes.
Peter Aartsma, Johan Asplund, Arvid Odland, Stefanie Reinhardt, and Hans Renssen
Biogeosciences, 18, 1577–1599,Short summary
In the literature, it is generally assumed that alpine lichen heaths keep their direct environment cool due to their relatively high albedo. However, we reveal that the soil temperature and soil heat flux are higher below lichens than below shrubs during the growing season, despite a lower net radiation for lichens. We also show that the differences in microclimatic conditions between these two vegetation types are more pronounced during warm and sunny days than during cold and cloudy days.
Oleg Sizov, Ekaterina Ezhova, Petr Tsymbarovich, Andrey Soromotin, Nikolay Prihod'ko, Tuukka Petäjä, Sergej Zilitinkevich, Markku Kulmala, Jaana Bäck, and Kajar Köster
Biogeosciences, 18, 207–228,Short summary
In changing climate, tundra is expected to turn into shrubs and trees, diminishing reindeer pasture and increasing risks of tick-borne diseases. However, this transition may require a disturbance. Fires in Siberia are increasingly widespread. We studied wildfire dynamics and tundra–forest transition over 60 years in northwest Siberia near the Arctic Circle. Based on satellite data analysis, we found that transition occurs in 40 %–85 % of burned tundra compared to 5 %–15 % in non-disturbed areas.
Kaveh Purkiani, André Paul, Annemiek Vink, Maren Walter, Michael Schulz, and Matthias Haeckel
Biogeosciences, 17, 6527–6544,Short summary
There has been a steady increase in interest in mining of deep-sea minerals in the eastern Pacific Ocean recently. The ocean state in this region is known to be highly influenced by rotating bodies of water (eddies), some of which can travel long distances in the ocean and impact the deeper layers of the ocean. Better insight into the variability of eddy activity in this region is of great help to mitigate the impact of the benthic ecosystem from future potential deep-sea mining activity.
Jing Yan, Nathaniel A. Bogie, and Teamrat A. Ghezzehei
Biogeosciences, 17, 6377–6392,Short summary
An uneven supply of water and nutrients in soils often drives how plants behave. We observed that plants extract all their required nutrients from dry soil patches in sufficient quantity, provided adequate water is available elsewhere in the root zone. Roots in nutrient-rich dry patches facilitate the nutrient acquisition by extensive growth, water release, and modifying water retention in their immediate environment. The findings are valuable in managing nutrient losses in agricultural systems.
Onur Kerimoglu, Yoana G. Voynova, Fatemeh Chegini, Holger Brix, Ulrich Callies, Richard Hofmeister, Knut Klingbeil, Corinna Schrum, and Justus E. E. van Beusekom
Biogeosciences, 17, 5097–5127,Short summary
In this study, using extensive field observations and a numerical model, we analyzed the physical and biogeochemical structure of a coastal system following an extreme flood event. Our results suggest that a number of anomalous observations were driven by a co-occurrence of peculiar meteorological conditions and increased riverine discharges. Our results call for attention to the combined effects of hydrological and meteorological extremes that are anticipated to increase in frequency.
Amandine Erktan, Matthias C. Rillig, Andrea Carminati, Alexandre Jousset, and Stefan Scheu
Biogeosciences, 17, 4961–4980,Short summary
Soil aggregation is crucial for soil functioning. While the role of bacteria and fungi in soil aggregation is well established, how predators feeding on microbes modify soil aggregation has hardly been investigated. We showed for the first time that protists modify soil aggregation, presumably through changes in the production of bacterial mucilage, and that collembolans reduce soil aggregation, presumably by reducing the abundance of saprotrophic fungi.
Wei Hu, Kotaro Murata, Chunlan Fan, Shu Huang, Hiromi Matsusaki, Pingqing Fu, and Daizhou Zhang
Biogeosciences, 17, 4477–4487,Short summary
This paper reports the first estimate of the status of bacteria in long-distance-transported Asian dust, demonstrating that airborne dust, which can carry viable and nonviable bacteria on particle surfaces, is an efficient medium for constantly spreading bacteria at regional and even global scales. Such data are essential to better model and understand the roles and activities of bioaerosols in environmental evolution and climate change and the potential risks of bioaerosols to human health.
Inge Grünberg, Evan J. Wilcox, Simon Zwieback, Philip Marsh, and Julia Boike
Biogeosciences, 17, 4261–4279,Short summary
Based on topsoil temperature data for different vegetation types at a low Arctic tundra site, we found large small-scale variability. Winter temperatures were strongly influenced by vegetation through its effects on snow. Summer temperatures were similar below most vegetation types and not consistently related to late summer permafrost thaw depth. Given that vegetation type defines the relationship between winter and summer soil temperature and thaw depth, it controls permafrost vulnerability.
Long Jiang, Theo Gerkema, Jacco C. Kromkamp, Daphne van der Wal, Pedro Manuel Carrasco De La Cruz, and Karline Soetaert
Biogeosciences, 17, 4135–4152,Short summary
A seaward increasing chlorophyll-a gradient is observed during the spring bloom in a Dutch tidal bay. Biophysical model runs indicate the roles of bivalve grazing and tidal import in shaping the gradient. Five common spatial phytoplankton patterns are summarized in global estuarine–coastal ecosystems: seaward increasing, seaward decreasing, concave with a chlorophyll maximum, weak spatial gradients, and irregular patterns.
Emil De Borger, Justin Tiano, Ulrike Braeckman, Tom Ysebaert, and Karline Soetaert
Biogeosciences, 17, 1701–1715,Short summary
By applying a novel technique to quantify organism-induced sediment–water column fluid exchange (bioirrigation), we show that organisms in subtidal (permanently submerged) areas have similar bioirrigation rates as those that inhabit intertidal areas (not permanently submerged), but organisms in the latter irrigate deeper burrows in this study. Our results expand on traditional methods to quantify bioirrigation rates and broaden the pool of field measurements of bioirrigation rates.
Sheila N. Estrada-Allis, Julio Sheinbaum Pardo, Joao M. Azevedo Correia de Souza, Cecilia Elizabeth Enríquez Ortiz, Ismael Mariño Tapia, and Jorge A. Herrera-Silveira
Biogeosciences, 17, 1087–1111,Short summary
Continental shelves are the most productive areas in the ocean and can have an important impact on the nutrient cycle as well as the climate system. The one in Yucatán is the largest shelf in the Gulf of Mexico. However, its nutrient budget remains unidentifiable. Here we propose not only a general nutrient budget for the Yucatán Shelf but also the physical processes responsible for its pathway modulation through a physical–biogeochemical coupled model of the whole Gulf of Mexico.
Ashley Dubnick, Martin Sharp, Brad Danielson, Alireza Saidi-Mehrabad, and Joel Barker
Biogeosciences, 17, 963–977,Short summary
We found that glaciers with basal temperatures near the melting point mobilize more solutes, nutrients, and microbes from the underlying substrate and are more likely to promote in situ biogeochemical activity than glaciers with basal temperatures well below the melting point. The temperature at the base of glaciers is therefore an important control on the biogeochemistry of ice near glacier beds, and, ultimately, the potential solutes, nutrients, and microbes exported from glaciated watersheds.
Audrey Delpech, Anna Conchon, Olivier Titaud, and Patrick Lehodey
Biogeosciences, 17, 833–850,Short summary
Micronekton is an important, yet poorly known, component of the trophic chain, which partly contributes to the storage of CO2 in the deep ocean thanks to biomass vertical migrations. In this study, we characterize the ideal sampling regions to estimate the amount of biomass that undergoes theses migrations. We find that observations made in warm, nondynamic and productive waters reduce the error of the estimation by 20 %. This result should likely serve for future in situ network deployment.
Filippos Tagklis, Takamitsu Ito, and Annalisa Bracco
Biogeosciences, 17, 231–244,Short summary
Deoxygenation of the oceans is potentially one of the most severe ecosystem stressors resulting from global warming given the high sensitivity of dissolved oxygen to ocean temperatures. Climate models suggest that despite the thermodynamic tendency of the oceans to lose oxygen, certain regions experience significant changes in the biologically driven O2 consumption, resulting in a resistance against deoxygenation. Overturning circulation changes are responsible for such a behavior.
Mohammad Abdul Halim, Han Y. H. Chen, and Sean C. Thomas
Biogeosciences, 16, 4357–4375,Short summary
Using field data collected over 4 years across a range of stand ages, we investigated how seasonal surface albedo in boreal forest varies with stand age, stand structure, and composition. Our results indicate that successional change in species composition is a key driver of age–related patterns in albedo, with hardwood species associated with higher albedo. The patterns described have important implications for both climate modeling and
climate–smartboreal forest management.
Paul A. Moore, Maxwell C. Lukenbach, Dan K. Thompson, Nick Kettridge, Gustaf Granath, and James M. Waddington
Biogeosciences, 16, 3491–3506,Short summary
Using very-high-resolution digital elevation models (DEMs), we assessed the basic structure and microtopographic variability of hummock–hollow plots at boreal and hemi-boreal sites primarily in North America. Using a simple model of peatland biogeochemical function, our results suggest that both surface heating and moss productivity may not be adequately resolved in models which only consider idealized hummock–hollow units.
Renee K. Gruber, Ryan J. Lowe, and James L. Falter
Biogeosciences, 16, 1921–1935,Short summary
Researchers from the University of Western Australia's Oceans Institute are studying large tides (up to 12 m range) that occur in the Kimberley region of Australia. These tides flush coral reefs with water rich in nutrients, which supports the growth of reef organisms. In this paper, we show how tidal cycles and seasons control nutrient availability on reefs. This study is among the first published accounts of reefs and water quality data in the remote and pristine Kimberley region.
Sergey A. Marakushev and Ol'ga V. Belonogova
Biogeosciences, 16, 1817–1828,Short summary
Among the existing theories of the autotrophic origin of life, CO2 is usually considered to be the carbon source for nascent autotrophic metabolism. However, ancestral carbon used in metabolism may have been derived from CH4 if the outflow of magma fluid to the surface of the Earth consisted mainly of methane. The hydrothermal system model is considered in the form of a phase diagram, which demonstrates the area of redox and P and T conditions favorable to development of primary methanotroph.
Venugopal Thushara, Puthenveettil Narayana Menon Vinayachandran, Adrian J. Matthews, Benjamin G. M. Webber, and Bastien Y. Queste
Biogeosciences, 16, 1447–1468,Short summary
Chlorophyll distribution in the ocean remains to be explored in detail, despite its climatic significance. Here, we document the vertical structure of chlorophyll in the Bay of Bengal using observations and a model. The shape of chlorophyll profiles, characterized by prominent deep chlorophyll maxima, varies in dynamically different regions, controlled by the monsoonal forcings. The present study provides new insights into the vertical distribution of chlorophyll, rarely observed by satellites.
Soeren Thomsen, Johannes Karstensen, Rainer Kiko, Gerd Krahmann, Marcus Dengler, and Anja Engel
Biogeosciences, 16, 979–998,Short summary
Physical and biogeochemical observations from an autonomous underwater vehicle in combination with ship-based measurements are used to investigate remote and local drivers of the oxygen and nutrient variability off Mauritania. Beside the transport of oxygen and nutrients characteristics from remote areas towards Mauritania also local remineralization of organic material close to the seabed seems to be important for the distribution of oxygen and nutrients.
Pascale Bouruet-Aubertot, Yannis Cuypers, Andrea Doglioli, Mathieu Caffin, Christophe Yohia, Alain de Verneil, Anne Petrenko, Dominique Lefèvre, Hervé Le Goff, Gilles Rougier, Marc Picheral, and Thierry Moutin
Biogeosciences, 15, 7485–7504,Short summary
The OUTPACE cruise took place between New Caledonia and French Polynesia. The main purpose was to understand how micro-organisms can survive in a very poor environment. One main source of nutrients is at depth, below the euphotic layer where micro-organisms live. The purpose of the turbulence measurements was to determine to which extent turbulence may
upliftnutrients into the euphotic layer. The origin of the turbulence that was found contrasted along the transect was also determined.
Daniel D. Richter, Sharon A. Billings, Peter M. Groffman, Eugene F. Kelly, Kathleen A. Lohse, William H. McDowell, Timothy S. White, Suzanne Anderson, Dennis D. Baldocchi, Steve Banwart, Susan Brantley, Jean J. Braun, Zachary S. Brecheisen, Charles W. Cook, Hilairy E. Hartnett, Sarah E. Hobbie, Jerome Gaillardet, Esteban Jobbagy, Hermann F. Jungkunst, Clare E. Kazanski, Jagdish Krishnaswamy, Daniel Markewitz, Katherine O'Neill, Clifford S. Riebe, Paul Schroeder, Christina Siebe, Whendee L. Silver, Aaron Thompson, Anne Verhoef, and Ganlin Zhang
Biogeosciences, 15, 4815–4832,Short summary
As knowledge in biology and geology explodes, science becomes increasingly specialized. Given the overlap of the environmental sciences, however, the explosion in knowledge inevitably creates opportunities for interconnecting the biogeosciences. Here, 30 scientists emphasize the opportunities for biogeoscience collaborations across the world’s remarkable long-term environmental research networks that can advance science and engage larger scientific and public audiences.
Ivy Frenger, Matthias Münnich, and Nicolas Gruber
Biogeosciences, 15, 4781–4798,Short summary
Although mesoscale ocean eddies are ubiquitous in the Southern Ocean (SO), their regional and seasonal association with phytoplankton has not been quantified. We identify over 100 000 eddies and determine the associated phytoplankton biomass anomalies using satellite-based chlorophyll (Chl) as a proxy. The emerging Chl anomalies can be explained largely by lateral advection of Chl by eddies. This impact of eddies on phytoplankton may implicate downstream effects on SO biogeochemical properties.
Yi Sun, Xiong Z. He, Fujiang Hou, Zhaofeng Wang, and Shenghua Chang
Biogeosciences, 15, 4233–4243,Short summary
To investigate how grazing alters litter composition, quality and decomposition, we collected litter from grazing (GP) and grazing exclusion paddocks (GEP) and incubated them in situ and across sites. Grazing increased litter N and grazing exclusion increased litter mass of palatable species and promoted SOC. Litter decomposed faster in GP and N was opposite. Site environment had more impact on litter decomposition. Results may be helpful in developing strategies to restore degraded grasslands.
Louise Rousselet, Alain de Verneil, Andrea M. Doglioli, Anne A. Petrenko, Solange Duhamel, Christophe Maes, and Bruno Blanke
Biogeosciences, 15, 2411–2431,Short summary
The patterns of the large- and fine-scale surface circulation on biogeochemical and biological distributions are examined in the western tropical South Pacific (WTSP) in the context of the OUTPACE oceanographic cruise. The combined use of in situ and satellite data allows for the identification of water mass transport pathways and fine-scale structures, such as fronts, that drive surface distribution of tracers and microbial community structures.
Alain de Verneil, Louise Rousselet, Andrea M. Doglioli, Anne A. Petrenko, Christophe Maes, Pascale Bouruet-Aubertot, and Thierry Moutin
Biogeosciences, 15, 2125–2147,Short summary
Oceanographic campaigns to measure biogeochemical processes popularly deploy drifters with onboard incubations to stay in a single body of water. Here, we aggregate physical data taken during such a cruise, OUTPACE, to independently test in a new approach whether the drifter really stayed in what can be considered a single biological or chemical environment. This study concludes that future campaigns would benefit from similar data collection and analysis to validate their sampling strategy.
Susan L. Brantley, David M. Eissenstat, Jill A. Marshall, Sarah E. Godsey, Zsuzsanna Balogh-Brunstad, Diana L. Karwan, Shirley A. Papuga, Joshua Roering, Todd E. Dawson, Jaivime Evaristo, Oliver Chadwick, Jeffrey J. McDonnell, and Kathleen C. Weathers
Biogeosciences, 14, 5115–5142,Short summary
This review represents the outcome from an invigorating workshop discussion that involved tree physiologists, geomorphologists, ecologists, geochemists, and hydrologists and developed nine hypotheses that could be tested. We argue these hypotheses point to the essence of issues we must explore if we are to understand how the natural system of the earth surface evolves, and how humans will affect its evolution. This paper will create discussion and interest both before and after publication.
Johanne H. Rydsaa, Frode Stordal, Anders Bryn, and Lena M. Tallaksen
Biogeosciences, 14, 4209–4227,Short summary
We investigate the atmospheric sensitivity to an expansion in shrub and tree cover in the northern Fennoscandia region. We applied a regional weather and climate model in evaluating biophysical effects of increased shrub cover at a fine resolution. We find that shrub cover increase causes a warming that is sensitive to the shrub and tree heights. Cooling effects include increased snow cover, cloud cover, and precipitation. We show that the net warming will likely increase in the future.
Qian Cai, Yulong Zhang, Zhanxiang Sun, Jiaming Zheng, Wei Bai, Yue Zhang, Yang Liu, Liangshan Feng, Chen Feng, Zhe Zhang, Ning Yang, Jochem B. Evers, and Lizhen Zhang
Biogeosciences, 14, 3851–3858,Short summary
Large yield gaps exist in rain-fed maize in semi-arid regions caused by frequent droughts halfway through the growing period due to uneven distribution of rainfall. It can be questioned whether irrigation systems are economically and ecologically required. Maize yield was not affected by mild water stress due to the morphological plasticity in root growth. Our results help to mitigate drought risk in dry-land agriculture.
Jörg Schwinger, Jerry Tjiputra, Nadine Goris, Katharina D. Six, Alf Kirkevåg, Øyvind Seland, Christoph Heinze, and Tatiana Ilyina
Biogeosciences, 14, 3633–3648,Short summary
Transient global warming under the high emission scenario RCP8.5 is amplified by up to 6 % if a pH dependency of marine DMS production is assumed. Importantly, this additional warming is not spatially homogeneous but shows a pronounced north–south gradient. Over the Antarctic continent, the additional warming is almost twice the global average. In the Southern Ocean we find a small DMS–climate feedback that counteracts the original reduction of DMS production due to ocean acidification.
Madhavan Girijakumari Keerthi, Matthieu Lengaigne, Marina Levy, Jerome Vialard, Vallivattathillam Parvathi, Clément de Boyer Montégut, Christian Ethé, Olivier Aumont, Iyyappan Suresh, Valiya Parambil Akhil, and Pillathu Moolayil Muraleedharan
Biogeosciences, 14, 3615–3632,Short summary
The northern Arabian Sea hosts a winter chlorophyll bloom, which exhibits strong interannual variability. The processes responsible for this interannual variation of the bloom are investigated using observations and a model. The interannual fluctuations of the winter bloom are largely related to the interannual mixed-layer depth (MLD) anomalies, which are driven by net heat flux anomalies. MLD controls the bloom amplitude through a modulation of nutrient turbulent fluxes into the mixed layer.
Lixin Lyu, Susanne Suvanto, Pekka Nöjd, Helena M. Henttonen, Harri Mäkinen, and Qi-Bin Zhang
Biogeosciences, 14, 3083–3095,Short summary
Our results reveal that the change in the tree growth–climate relationship is similar along latitudinal and altitudinal gradients, especially during growing seasons. Moreover, the critical periods for climatic effects on tree radial growth occurred earlier at lower latitudes and altitudes than at the cold ends of the gradients. We further demonstrate the use of daily climate data, as they may disclose more precise gradient patterns that could not be detected if monthly climate data were used.
Sophie Clayton, Stephanie Dutkiewicz, Oliver Jahn, Christopher Hill, Patrick Heimbach, and Michael J. Follows
Biogeosciences, 14, 2877–2889,
Xiang Gong, Wensheng Jiang, Linhui Wang, Huiwang Gao, Emmanuel Boss, Xiaohong Yao, Shuh-Ji Kao, and Jie Shi
Biogeosciences, 14, 2371–2386,Short summary
The subsurface chlorophyll maximum layer (SCML) forms near the nitracline. By incorporating a piecewise function for the approximate Gaussian vertical profile of chlorophyll, we derive analytical solutions of a specified nutrient–phytoplankton model. Nitracline depth is deeper than SCML depth, and a thinner SCML corresponds to a steeper nitracline. A higher light attenuation coefficient leads to a shallower but steeper nitracline. Nitracline steepness is independent of surface light intensity.
Johannes Karstensen, Florian Schütte, Alice Pietri, Gerd Krahmann, Björn Fiedler, Damian Grundle, Helena Hauss, Arne Körtzinger, Carolin R. Löscher, Pierre Testor, Nuno Vieira, and Martin Visbeck
Biogeosciences, 14, 2167–2181,Short summary
High-resolution observational data from underwater gliders and ships are used to investigate drivers and pathways of nutrient upwelling in high-productive whirling ecosystems (eddies). The data suggest that the upwelling is created by the interaction of wind-induced internal waves with the local rotation of the eddy. Because of differences in nutrient and oxygen pathways, a low-oxygen core is established at shallow depth in the high-productive eddies.
Parvathi Vallivattathillam, Suresh Iyyappan, Matthieu Lengaigne, Christian Ethé, Jérôme Vialard, Marina Levy, Neetu Suresh, Olivier Aumont, Laure Resplandy, Hema Naik, and Wajih Naqvi
Biogeosciences, 14, 1541–1559,Short summary
During late boreal summer and fall, the west coast of India (WCI) experiences hypoxia, which turns into anoxia during some years. We analyze a coupled physical–biogeochemical simulation over the 1960–2012 period to investigate the physical processes influencing oxycline interannual variability off the WCI. We show that fall WCI oxycline fluctuations are strongly related to Indian Ocean Dipole (IOD), with positive IODs preventing anoxia, while negative IODs do not necessarily result in anoxia.
Yonss Saranga José, Heiner Dietze, and Andreas Oschlies
Biogeosciences, 14, 1349–1364,Short summary
This study aims to investigate the diverse subsurface nutrient patterns observed within anticyclonic eddies in the upwelling system off Peru. Two simulated anticyclonic eddies with opposing subsurface nitrate concentrations were analysed. The results show that diverse nutrient patterns within anticyclonic eddies are related to the presence of water mass from different origins at different depths, responding to variations in depth of the circulation strength at the edge of the eddy.
Gerardo Arturo Sánchez-Azofeifa, J. Antonio Guzmán-Quesada, Mauricio Vega-Araya, Carlos Campos-Vargas, Sandra Milena Durán, Nikhil D'Souza, Thomas Gianoli, Carlos Portillo-Quintero, and Iain Sharp
Biogeosciences, 14, 977–988,Short summary
Lianas (woody vines) tend to respond positively to disturbance and show high densities in secondary forests. Lianas are a key component of tropical forests because they may reduce carbon potential. Identifying tools for liana detection is therefore essential for monitoring changes in tropical forests. In this study, we describe how terrestrial laser scanning can be used to detect the presence of lianas in forest stands of different ages in secondary tropical dry forests at a regional scale.
Maximilian Weigand and Andreas Kemna
Biogeosciences, 14, 921–939,Short summary
Root systems are essential in nutrient uptake and translocation, but are difficult to characterize non-invasively with existing methods. We propose electrical impedance tomography (EIT) as a new tool for the imaging and monitoring of crop root systems. In a laboratory experiment we demonstrate the capability of the method to capture physiological responses of root systems with high spatial and temporal resolution. We conclude that EIT is a promising functional imaging technique for crop roots.
Florent Domine, Mathieu Barrere, and Samuel Morin
Biogeosciences, 13, 6471–6486,Short summary
Warming-induced shrub growth in the Arctic traps snow and modifies snow properties, hence the permafrost thermal regime. In the Canadian high Arctic, we measured snow physical properties in the presence and absence of willow shrubs (Salix richardsonii). Shrubs dramatically reduce snow density and thermal conductivity, seriously limiting soil winter cooling. Simulations taking into account only winter changes show that shrub growth leads to a ground winter warming of up to 13 °C.
Florian Schütte, Johannes Karstensen, Gerd Krahmann, Helena Hauss, Björn Fiedler, Peter Brandt, Martin Visbeck, and Arne Körtzinger
Biogeosciences, 13, 5865–5881,Short summary
Mesoscale eddies with very low–oxygen concentrations at shallow depth have been recently discovered in the eastern tropical North Atlantic. Our analysis shows that low oxygen eddies occur more frequent than expected and are found even close to the equator (8° N). From budget calculations we show that an oxygen reduction of 7 µmol/kg in the depth range of 50–150 m in the eastern tropical North Atlantic (peak reduction is 16 µmol/kg at 100 m depth) can be associated with the dispersion of these eddies.
Anthony Bouton, Emmanuelle Vennin, Julien Boulle, Aurélie Pace, Raphaël Bourillot, Christophe Thomazo, Arnaud Brayard, Guy Désaubliaux, Tomasz Goslar, Yusuke Yokoyama, Christophe Dupraz, and Pieter T. Visscher
Biogeosciences, 13, 5511–5526,Short summary
The modern hypersaline Great Salt Lake shows an extended modern and ancient microbial sedimentary system. This study on aerial images and field observations discusses the non-random distribution patterns of microbial deposits along linear alignments following isobaths, polygonal geometry or straight alignments along a topographic drop-off. This particular distribution of microbial deposits brings further insights to the reconstruction of paleoenvironments and paleoclimatic changes.
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Observations reveal that in some regions phytoplankton biomass increases during the wintertime when growth conditions are sub-optimal, which has been attributed to a release from grazing during mixed layer deepening. Measurements of grazer populations to support this theory are lacking. We demonstrate that a release from grazing when the winter mixed layer is deepening holds only for certain grazing models, extending the use of phytoplankton observations to make inferences about grazer dynamics.
Observations reveal that in some regions phytoplankton biomass increases during the wintertime...