Articles | Volume 18, issue 5
https://doi.org/10.5194/bg-18-1873-2021
© Author(s) 2021. 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-18-1873-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
18 Mar 2021
Research article |
| 18 Mar 2021
| 18 Mar 2021
A 2-decade (1988–2009) record of diatom fluxes in the Mauritanian coastal upwelling: impact of low-frequency forcing and a two-step shift in the species composition
MARUM – Center for Marine Environmental Sciences, University of
Bremen, Leobener Str. 8, Bremen 28359, Germany
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine
Research, Am Alten Hafen 26, Bremerhaven 27568, Germany
Simon Ramondenc
MARUM – Center for Marine Environmental Sciences, University of
Bremen, Leobener Str. 8, Bremen 28359, Germany
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine
Research, Am Alten Hafen 26, Bremerhaven 27568, Germany
Gerhard Fischer
MARUM – Center for Marine Environmental Sciences, University of
Bremen, Leobener Str. 8, Bremen 28359, Germany
University of Bremen, Geosciences Department, Klagenfurter Str., Bremen 28359, Germany
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Diatoms are the dominant primary producers of the most productive and best fishing areas of the modern ocean, the coastal upwelling systems. This turns them into important contributors to the biological pump and climate change. To help untangle their response to warming climate, we compare the worldwide diatom sedimentary abundance (SDA) to environmental variables and find that the capacity of diatoms to take up silicic acid sets an upper limit on global export production in these ocean regions.
Gerhard Fischer, Johannes Karstensen, Oscar Romero, Karl-Heinz Baumann, Barbara Donner, Jens Hefter, Gesine Mollenhauer, Morten Iversen, Björn Fiedler, Ivanice Monteiro, and Arne Körtzinger
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Short summary
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We highlight the proxy potential of foraminiferal Mn/Ca determined by secondary ion mass spectrometry and flow-through inductively coupled plasma optical emission spectroscopy for recording changes in bottom-water oxygen conditions. Comparisons with Mn sediment bulk measurements from the same sediment core largely agree with the results. High foraminiferal Mn/Ca occurs in samples from times of high productivity export and corresponds with the benthic foraminiferal faunal composition.
J. Karstensen, B. Fiedler, F. Schütte, P. Brandt, A. Körtzinger, G. Fischer, R. Zantopp, J. Hahn, M. Visbeck, and D. Wallace
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O. Cartapanis, K. Tachikawa, O. E. Romero, and E. Bard
Clim. Past, 10, 405–418, https://doi.org/10.5194/cp-10-405-2014, https://doi.org/10.5194/cp-10-405-2014, 2014
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Due to climate change, it is projected that extreme rainfall events, which bring terrestrial matter into coastal seas, will occur more frequently in the Mediterranean region. To test the effects of runoffs of terrestrial matter on plankton communities from Mediterranean coastal waters, an in situ mesocosm experiment was conducted. The simulated runoff affected key processes mediated by plankton, such as primary production and respiration, suggesting major consequences of such events.
Chueh-Chen Tung, Yu-Shih Lin, Jian-Xiang Liao, Tzu-Hsuan Tu, James T. Liu, Li-Hung Lin, Pei-Ling Wang, and Chih-Lin Wei
Biogeosciences, 21, 1729–1756, https://doi.org/10.5194/bg-21-1729-2024, https://doi.org/10.5194/bg-21-1729-2024, 2024
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This study contrasts seabed food webs between a river-fed, high-energy canyon and the nearby slope. We show higher organic carbon (OC) flows through the canyon than the slope. Bacteria dominated the canyon, while seabed fauna contributed more to the slope food web. Due to frequent perturbation, the canyon had a lower faunal stock and OC recycling. Only 4 % of the seabed OC flux enters the canyon food web, suggesting a significant role of the river-fed canyon in transporting OC to the deep sea.
Joost de Vries, Fanny Monteiro, Gerald Langer, Colin Brownlee, and Glen Wheeler
Biogeosciences, 21, 1707–1727, https://doi.org/10.5194/bg-21-1707-2024, https://doi.org/10.5194/bg-21-1707-2024, 2024
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Calcifying phytoplankton (coccolithophores) utilize a life cycle in which they can grow and divide into two different phases. These two phases (HET and HOL) vary in terms of their physiology and distributions, with many unknowns about what the key differences are. Using a combination of lab experiments and model simulations, we find that nutrient storage is a critical difference between the two phases and that this difference allows them to inhabit different nitrogen input regimes.
Theodor Kindeberg, Karl Michael Attard, Jana Hüller, Julia Müller, Cintia Organo Quintana, and Eduardo Infantes
Biogeosciences, 21, 1685–1705, https://doi.org/10.5194/bg-21-1685-2024, https://doi.org/10.5194/bg-21-1685-2024, 2024
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Seagrass meadows are hotspots for biodiversity and productivity, and planting seagrass is proposed as a tool for mitigating biodiversity loss and climate change. We assessed seagrass planted in different years and found that benthic oxygen and carbon fluxes increased as the seabed developed from bare sediments to a mature seagrass meadow. This increase was partly linked to the diversity of colonizing algae which increased the light-use efficiency of the seagrass meadow community.
Anna-Selma van der Kaaden, Sandra R. Maier, Siluo Chen, Laurence H. De Clippele, Evert de Froe, Theo Gerkema, Johan van de Koppel, Furu Mienis, Christian Mohn, Max Rietkerk, Karline Soetaert, and Dick van Oevelen
Biogeosciences, 21, 973–992, https://doi.org/10.5194/bg-21-973-2024, https://doi.org/10.5194/bg-21-973-2024, 2024
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Combining hydrodynamic simulations and annotated videos, we separated which hydrodynamic variables that determine reef cover are engineered by cold-water corals and which are not. Around coral mounds, hydrodynamic zones seem to create a typical reef zonation, restricting corals from moving deeper (the expected response to climate warming). But non-engineered downward velocities in winter (e.g. deep winter mixing) seem more important for coral reef growth than coral engineering.
Xiaoke Xin, Giulia Faucher, and Ulf Riebesell
Biogeosciences, 21, 761–772, https://doi.org/10.5194/bg-21-761-2024, https://doi.org/10.5194/bg-21-761-2024, 2024
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Ocean alkalinity enhancement (OAE) is a promising approach to remove CO2 by accelerating natural rock weathering. However, some of the alkaline substances contain trace metals which could be toxic to marine life. By exposing three representative phytoplankton species to Ni released from alkaline materials, we observed varying responses of phytoplankton to nickel concentrations, suggesting caution should be taken and toxic thresholds should be avoided in OAE with Ni-rich materials.
Evert de Froe, Igor Yashayaev, Christian Mohn, Johanne Vad, Furu Mienis, Gerard Duineveld, Ellen Kenchington, Erica Head, Steve Ross, Sabena Blackbird, George Wolff, Murray Roberts, Barry MacDonald, Graham Tulloch, and Dick van Oevelen
EGUsphere, https://doi.org/10.31223/X58968, https://doi.org/10.31223/X58968, 2024
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Deep-sea sponge grounds are distributed globally and are considered hotspots of biological diversity and biogeochemical cycling. To date, little is known about the environmental constraints that control where deep-sea sponge grounds occur and what conditions favor high sponge biomass. Here, we characterize oceanographic conditions at two contrasting sponge grounds. Our results imply that sponges and associated fauna benefit from strong tidal currents and favorable regional ocean currents.
Olmo Miguez-Salas, Angelika Brandt, Henry Knauber, and Torben Riehl
Biogeosciences, 21, 641–655, https://doi.org/10.5194/bg-21-641-2024, https://doi.org/10.5194/bg-21-641-2024, 2024
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In the deep sea, the interaction between benthic fauna (tracemakers) and substrate can be preserved as traces (i.e. lebensspuren), which are common features of seafloor landscapes, rendering them promising proxies for inferring biodiversity from marine images. No general correlation was observed between traces and benthic fauna. However, a local correlation was observed between specific stations depending on unknown tracemakers, tracemaker behaviour, and lebensspuren morphotypes.
Cale A. Miller, Pierre Urrutti, Jean-Pierre Gattuso, Steeve Comeau, Anaïs Lebrun, Samir Alliouane, Robert W. Schlegel, and Frédéric Gazeau
Biogeosciences, 21, 315–333, https://doi.org/10.5194/bg-21-315-2024, https://doi.org/10.5194/bg-21-315-2024, 2024
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This work describes an experimental system that can replicate and manipulate environmental conditions in marine or aquatic systems. Here, we show how the temperature and salinity of seawater delivered from a fjord is manipulated to experimental tanks on land. By constantly monitoring temperature and salinity in each tank via a computer program, the system continuously adjusts automated flow valves to ensure the seawater in each tank matches the targeted experimental conditions.
Rachel A. Kruft Welton, George Hoppit, Daniela N. Schmidt, James D. Witts, and Benjamin C. Moon
Biogeosciences, 21, 223–239, https://doi.org/10.5194/bg-21-223-2024, https://doi.org/10.5194/bg-21-223-2024, 2024
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We conducted a meta-analysis of known experimental literature examining how marine bivalve growth rates respond to climate change. Growth is usually negatively impacted by climate change. Bivalve eggs/larva are generally more vulnerable than either juveniles or adults. Available data on the bivalve response to climate stressors are biased towards early growth stages (commercially important in the Global North), and many families have only single experiments examining climate change impacts.
Vincent Mouchi, Christophe Pecheyran, Fanny Claverie, Cécile Cathalot, Marjolaine Matabos, Yoan Germain, Olivier Rouxel, Didier Jollivet, Thomas Broquet, and Thierry Comtet
Biogeosciences, 21, 145–160, https://doi.org/10.5194/bg-21-145-2024, https://doi.org/10.5194/bg-21-145-2024, 2024
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The impact of deep-sea mining will depend critically on the ability of larval dispersal of hydrothermal mollusks to connect and replenish natural populations. However, assessing connectivity is extremely challenging, especially in the deep sea. Here, we investigate the potential of using the chemical composition of larval shells to discriminate larval origins between multiple hydrothermal sites in the southwest Pacific. Our results confirm that this method can be applied with high accuracy.
Hyunjae Chung, Jikang Park, Mijin Park, Yejin Kim, Unyoung Chun, Sukyoung Yun, Won Sang Lee, Seung-Tae Yoon, and Won Young Lee
EGUsphere, https://doi.org/10.5194/egusphere-2023-2757, https://doi.org/10.5194/egusphere-2023-2757, 2024
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Understanding how marine animals adapt to spatial and temporal shifts in oceanographic conditions is of utmost importance. In this paper, we investigated the influence of changes in seawater properties on the seasonal behavior of Weddell seals in the Ross Sea, Antarctica. Our findings could serve as a baseline and establish a foundational understanding for future research, particularly concerning the impact of marine environmental changes on the ecosystem of the Ross Sea Marine Protected Area.
Anna-Marie Winter, Nadezda Vasilyeva, and Artem Vladimirov
Biogeosciences, 20, 3683–3716, https://doi.org/10.5194/bg-20-3683-2023, https://doi.org/10.5194/bg-20-3683-2023, 2023
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There is an increasing number of fish in poor state, and many do not recover, even when fishing pressure is ceased. An Allee effect can hinder population recovery because it suppresses the fish's productivity at low abundance. With a model fitted to 17 Atlantic cod stocks, we find that ocean warming and fishing can cause an Allee effect. If present, the Allee effect hinders fish recovery. This shows that Allee effects are dynamic, not uncommon, and calls for precautionary management measures.
Afrah Alothman, Daffne López-Sandoval, Carlos M. Duarte, and Susana Agustí
Biogeosciences, 20, 3613–3624, https://doi.org/10.5194/bg-20-3613-2023, https://doi.org/10.5194/bg-20-3613-2023, 2023
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This study investigates bacterial dissolved inorganic carbon (DIC) fixation in the Red Sea, an oligotrophic ecosystem, using stable-isotope labeling and spectroscopy. The research reveals that bacterial DIC fixation significantly contributes to total DIC fixation, in the surface and deep water. The study demonstrates that as primary production decreases, the role of bacterial DIC fixation increases, emphasizing its importance with photosynthesis in estimating oceanic carbon dioxide production.
Arianna Zampollo, Thomas Cornulier, Rory O'Hara Murray, Jacqueline Fiona Tweddle, James Dunning, and Beth E. Scott
Biogeosciences, 20, 3593–3611, https://doi.org/10.5194/bg-20-3593-2023, https://doi.org/10.5194/bg-20-3593-2023, 2023
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This paper highlights the use of the bottom mixed layer depth (BMLD: depth between the end of the pycnocline and the mixed layer below) to investigate subsurface Chlorophyll a (a proxy of primary production) in temperate stratified shelf waters. The strict correlation between subsurface Chl a and BMLD becomes relevant in shelf-productive waters where multiple stressors (e.g. offshore infrastructure) will change the stratification--mixing balance and related carbon fluxes.
Marco Fusi, Sylvain Rigaud, Giovanna Guadagnin, Alberto Barausse, Ramona Marasco, Daniele Daffonchio, Julie Régis, Louison Huchet, Capucine Camin, Laura Pettit, Cristina Vina-Herbon, and Folco Giomi
Biogeosciences, 20, 3509–3521, https://doi.org/10.5194/bg-20-3509-2023, https://doi.org/10.5194/bg-20-3509-2023, 2023
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Oxygen availability in marine water and freshwater is very variable at daily and seasonal scales. The dynamic nature of oxygen fluctuations has important consequences for animal and microbe physiology and ecology, yet it is not fully understood. In this paper, we showed the heterogeneous nature of the aquatic oxygen landscape, which we defined here as the
oxyscape, and we addressed the importance of considering the oxyscape in the modelling and managing of aquatic ecosystems.
Anne L. Morée, Tayler M. Clarke, William W. L. Cheung, and Thomas L. Frölicher
Biogeosciences, 20, 2425–2454, https://doi.org/10.5194/bg-20-2425-2023, https://doi.org/10.5194/bg-20-2425-2023, 2023
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Ocean temperature and oxygen shape marine habitats together with species’ characteristics. We calculated the impacts of projected 21st-century warming and oxygen loss on the contemporary habitat volume of 47 marine species and described the drivers of these impacts. Most species lose less than 5 % of their habitat at 2 °C of global warming, but some species incur losses 2–3 times greater than that. We also calculate which species may be most vulnerable to climate change and why this is the case.
Markus A. Min, David M. Needham, Sebastian Sudek, Nathan Kobun Truelove, Kathleen J. Pitz, Gabriela M. Chavez, Camille Poirier, Bente Gardeler, Elisabeth von der Esch, Andrea Ludwig, Ulf Riebesell, Alexandra Z. Worden, and Francisco P. Chavez
Biogeosciences, 20, 1277–1298, https://doi.org/10.5194/bg-20-1277-2023, https://doi.org/10.5194/bg-20-1277-2023, 2023
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Emerging molecular methods provide new ways of understanding how marine communities respond to changes in ocean conditions. Here, environmental DNA was used to track the temporal evolution of biological communities in the Peruvian coastal upwelling system and in an adjacent enclosure where upwelling was simulated. We found that the two communities quickly diverged, with the open ocean being one found during upwelling and the enclosure evolving to one found under stratified conditions.
Wojciech Majewski, Witold Szczuciński, and Andrew J. Gooday
Biogeosciences, 20, 523–544, https://doi.org/10.5194/bg-20-523-2023, https://doi.org/10.5194/bg-20-523-2023, 2023
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We studied foraminifera living in the fjords of South Georgia, a sub-Antarctic island sensitive to climate change. As conditions in water and on the seafloor vary, different associations of these microorganisms dominate far inside, in the middle, and near fjord openings. Assemblages in inner and middle parts of fjords are specific to South Georgia, but they may become widespread with anticipated warming. These results are important for interpretating fossil records and monitoring future change.
Allanah Joy Paul, Lennart Thomas Bach, Javier Arístegui, Elisabeth von der Esch, Nauzet Hernández-Hernández, Jonna Piiparinen, Laura Ramajo, Kristian Spilling, and Ulf Riebesell
Biogeosciences, 19, 5911–5926, https://doi.org/10.5194/bg-19-5911-2022, https://doi.org/10.5194/bg-19-5911-2022, 2022
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We investigated how different deep water chemistry and biology modulate the response of surface phytoplankton communities to upwelling in the Peruvian coastal zone. Our results show that the most influential drivers were the ratio of inorganic nutrients (N : P) and the microbial community present in upwelling source water. These led to unexpected and variable development in the phytoplankton assemblage that could not be predicted by the amount of inorganic nutrients alone.
Hanna M. Kauko, Philipp Assmy, Ilka Peeken, Magdalena Różańska-Pluta, Józef M. Wiktor, Gunnar Bratbak, Asmita Singh, Thomas J. Ryan-Keogh, and Sebastien Moreau
Biogeosciences, 19, 5449–5482, https://doi.org/10.5194/bg-19-5449-2022, https://doi.org/10.5194/bg-19-5449-2022, 2022
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This article studies phytoplankton (microscopic
plantsin the ocean capable of photosynthesis) in Kong Håkon VII Hav in the Southern Ocean. Different species play different roles in the ecosystem, and it is therefore important to assess the species composition. We observed that phytoplankton blooms in this area are formed by large diatoms with strong silica armors, which can lead to high silica (and sometimes carbon) export to depth and be important prey for krill.
Chloe Carbonne, Steeve Comeau, Phoebe T. W. Chan, Keyla Plichon, Jean-Pierre Gattuso, and Núria Teixidó
Biogeosciences, 19, 4767–4777, https://doi.org/10.5194/bg-19-4767-2022, https://doi.org/10.5194/bg-19-4767-2022, 2022
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For the first time, our study highlights the synergistic effects of a 9-month warming and acidification combined stress on the early life stages of a Mediterranean azooxanthellate coral, Astroides calycularis. Our results predict a decrease in dispersion, settlement, post-settlement linear extention, budding and survival under future global change and that larvae and recruits of A. calycularis are stages of interest for this Mediterranean coral resistance, resilience and conservation.
Iris E. Hendriks, Anna Escolano-Moltó, Susana Flecha, Raquel Vaquer-Sunyer, Marlene Wesselmann, and Núria Marbà
Biogeosciences, 19, 4619–4637, https://doi.org/10.5194/bg-19-4619-2022, https://doi.org/10.5194/bg-19-4619-2022, 2022
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Seagrasses are marine plants with the capacity to act as carbon sinks due to their high primary productivity, using carbon for growth. This capacity can play a key role in climate change mitigation. We compiled and published data showing that two Mediterranean seagrass species have different metabolic rates, while the study method influences the rates of the measurements. Most communities act as carbon sinks, while the western basin might be more productive than the eastern Mediterranean.
Raúl Tapia, Sze Ling Ho, Hui-Yu Wang, Jeroen Groeneveld, and Mahyar Mohtadi
Biogeosciences, 19, 3185–3208, https://doi.org/10.5194/bg-19-3185-2022, https://doi.org/10.5194/bg-19-3185-2022, 2022
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We report census counts of planktic foraminifera in depth-stratified plankton net samples off Indonesia. Our results show that the vertical distribution of foraminifera species routinely used in paleoceanographic reconstructions varies in hydrographically distinct regions, likely in response to food availability. Consequently, the thermal gradient based on mixed layer and thermocline dwellers also differs for these regions, suggesting potential implications for paleoceanographic reconstructions.
Ricardo González-Gil, Neil S. Banas, Eileen Bresnan, and Michael R. Heath
Biogeosciences, 19, 2417–2426, https://doi.org/10.5194/bg-19-2417-2022, https://doi.org/10.5194/bg-19-2417-2022, 2022
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In oceanic waters, the accumulation of phytoplankton biomass in winter, when light still limits growth, is attributed to a decrease in grazing as the mixed layer deepens. However, in coastal areas, it is not clear whether winter biomass can accumulate without this deepening. Using 21 years of weekly data, we found that in the Scottish coastal North Sea, the seasonal increase in light availability triggers the accumulation of phytoplankton biomass in winter, when light limitation is strongest.
Birgit Koehler, Mårten Erlandsson, Martin Karlsson, and Lena Bergström
Biogeosciences, 19, 2295–2312, https://doi.org/10.5194/bg-19-2295-2022, https://doi.org/10.5194/bg-19-2295-2022, 2022
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Understanding species richness patterns remains a challenge for biodiversity management. We estimated fish species richness over a coastal salinity gradient (3–32) with a method that allowed comparing data from various sources. Species richness was 3-fold higher at high vs. low salinity, and salinity influenced species’ habitat preference, mobility and feeding type. If climate change causes upper-layer freshening of the Baltic Sea, further shifts along the identified patterns may be expected.
Uri Obolski, Thomas Wichard, Alvaro Israel, Alexander Golberg, and Alexander Liberzon
Biogeosciences, 19, 2263–2271, https://doi.org/10.5194/bg-19-2263-2022, https://doi.org/10.5194/bg-19-2263-2022, 2022
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The algal genus Ulva plays a major role in coastal ecosystems worldwide and is a promising prospect as an seagriculture crop. A substantial hindrance to cultivating Ulva arises from sudden sporulation, leading to biomass loss. This process is not yet well understood. Here, we characterize the dynamics of Ulva growth, considering the potential impact of sporulation inhibitors, using a mathematical model. Our findings are an essential step towards understanding the dynamics of Ulva growth.
Emanuela Fanelli, Samuele Menicucci, Sara Malavolti, Andrea De Felice, and Iole Leonori
Biogeosciences, 19, 1833–1851, https://doi.org/10.5194/bg-19-1833-2022, https://doi.org/10.5194/bg-19-1833-2022, 2022
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Zooplankton play a key role in marine ecosystems, forming the base of the marine food web and a link between primary producers and higher-order consumers, such as fish. This aspect is crucial in the Adriatic basin, one of the most productive and overexploited areas of the Mediterranean Sea. A better understanding of community and food web structure and their response to water mass changes is essential under a global warming scenario, as zooplankton are sensitive to climate change.
Masaya Yoshikai, Takashi Nakamura, Rempei Suwa, Sahadev Sharma, Rene Rollon, Jun Yasuoka, Ryohei Egawa, and Kazuo Nadaoka
Biogeosciences, 19, 1813–1832, https://doi.org/10.5194/bg-19-1813-2022, https://doi.org/10.5194/bg-19-1813-2022, 2022
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This study presents a new individual-based vegetation model to investigate salinity control on mangrove productivity. The model incorporates plant hydraulics and tree competition and predicts unique and complex patterns of mangrove forest structures that vary across soil salinity gradients. The presented model does not hold an empirical expression of salinity influence on productivity and thus may provide a better understanding of mangrove forest dynamics in future climate change.
Coulson A. Lantz, William Leggat, Jessica L. Bergman, Alexander Fordyce, Charlotte Page, Thomas Mesaglio, and Tracy D. Ainsworth
Biogeosciences, 19, 891–906, https://doi.org/10.5194/bg-19-891-2022, https://doi.org/10.5194/bg-19-891-2022, 2022
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Coral bleaching events continue to drive the degradation of coral reefs worldwide. In this study we measured rates of daytime coral reef community calcification and photosynthesis during a reef-wide bleaching event. Despite a measured decline in coral health across several taxa, there was no change in overall daytime community calcification and photosynthesis. These findings highlight potential limitations of these community-level metrics to reflect actual changes in coral health.
Hyewon Heather Kim, Jeff S. Bowman, Ya-Wei Luo, Hugh W. Ducklow, Oscar M. Schofield, Deborah K. Steinberg, and Scott C. Doney
Biogeosciences, 19, 117–136, https://doi.org/10.5194/bg-19-117-2022, https://doi.org/10.5194/bg-19-117-2022, 2022
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Heterotrophic marine bacteria are tiny organisms responsible for taking up organic matter in the ocean. Using a modeling approach, this study shows that characteristics (taxonomy and physiology) of bacteria are associated with a subset of ecological processes in the coastal West Antarctic Peninsula region, a system susceptible to global climate change. This study also suggests that bacteria will become more active, in particular large-sized cells, in response to changing climates in the region.
Alice E. Webb, Didier M. de Bakker, Karline Soetaert, Tamara da Costa, Steven M. A. C. van Heuven, Fleur C. van Duyl, Gert-Jan Reichart, and Lennart J. de Nooijer
Biogeosciences, 18, 6501–6516, https://doi.org/10.5194/bg-18-6501-2021, https://doi.org/10.5194/bg-18-6501-2021, 2021
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The biogeochemical behaviour of shallow reef communities is quantified to better understand the impact of habitat degradation and species composition shifts on reef functioning. The reef communities investigated barely support reef functions that are usually ascribed to conventional coral reefs, and the overall biogeochemical behaviour is found to be similar regardless of substrate type. This suggests a decrease in functional diversity which may therefore limit services provided by this reef.
Emmanuel Devred, Andrea Hilborn, and Cornelia Elizabeth den Heyer
Biogeosciences, 18, 6115–6132, https://doi.org/10.5194/bg-18-6115-2021, https://doi.org/10.5194/bg-18-6115-2021, 2021
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A theoretical model of grey seal seasonal abundance on Sable Island (SI) coupled with chlorophyll-a concentration [chl-a] measured by satellite revealed the impact of seal nitrogen fertilization on the surrounding waters of SI, Canada. The increase in seals from about 100 000 in 2003 to about 360 000 in 2018 during the breeding season is consistent with an increase in [chl-a] leeward of SI. The increase in seal abundance explains 8 % of the [chl-a] increase.
Julie Meilland, Michael Siccha, Maike Kaffenberger, Jelle Bijma, and Michal Kucera
Biogeosciences, 18, 5789–5809, https://doi.org/10.5194/bg-18-5789-2021, https://doi.org/10.5194/bg-18-5789-2021, 2021
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Planktonic foraminifera population dynamics has long been assumed to be controlled by synchronous reproduction and ontogenetic vertical migration (OVM). Due to contradictory observations, this concept became controversial. We here test it in the Atlantic ocean for four species of foraminifera representing the main clades. Our observations support the existence of synchronised reproduction and OVM but show that more than half of the population does not follow the canonical trajectory.
Federica Maggioni, Mireille Pujo-Pay, Jérome Aucan, Carlo Cerrano, Barbara Calcinai, Claude Payri, Francesca Benzoni, Yves Letourneur, and Riccardo Rodolfo-Metalpa
Biogeosciences, 18, 5117–5140, https://doi.org/10.5194/bg-18-5117-2021, https://doi.org/10.5194/bg-18-5117-2021, 2021
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Based on current experimental evidence, climate change will affect up to 90 % of coral reefs worldwide. The originality of this study arises from our recent discovery of an exceptional study site where environmental conditions (temperature, pH, and oxygen) are even worse than those forecasted for the future.
While these conditions are generally recognized as unfavorable for marine life, we found a rich and abundant coral reef thriving under such extreme environmental conditions.
Nisan Sariaslan and Martin R. Langer
Biogeosciences, 18, 4073–4090, https://doi.org/10.5194/bg-18-4073-2021, https://doi.org/10.5194/bg-18-4073-2021, 2021
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Analyses of foraminiferal assemblages from the Mamanguape mangrove estuary (northern Brazil) revealed highly diverse, species-rich, and structurally complex biotas. The atypical fauna resembles shallow-water offshore assemblages and are interpreted to be the result of highly saline ocean waters penetrating deep into the estuary. The findings contrast with previous studies, have implications for the fossil record, and provide novel perspectives for reconstructing mangrove environments.
Jutta E. Wollenburg, Jelle Bijma, Charlotte Cremer, Ulf Bickmeyer, and Zora Mila Colomba Zittier
Biogeosciences, 18, 3903–3915, https://doi.org/10.5194/bg-18-3903-2021, https://doi.org/10.5194/bg-18-3903-2021, 2021
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Cultured at in situ high-pressure conditions Cibicides and Cibicidoides taxa develop lasting ectoplasmic structures that cannot be retracted or resorbed. An ectoplasmic envelope surrounds their test and may protect the shell, e.g. versus carbonate aggressive bottom water conditions. Ectoplasmic roots likely anchor the specimens in areas of strong bottom water currents, trees enable them to elevate themselves above ground, and twigs stabilize and guide the retractable pseudopodial network.
Kumar Nimit
Biogeosciences, 18, 3631–3635, https://doi.org/10.5194/bg-18-3631-2021, https://doi.org/10.5194/bg-18-3631-2021, 2021
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The Indian Ocean Rim hosts many of the underdeveloped and emerging economies that depend on ocean resources for the livelihood of millions. Operational ocean information services cater to the requirements of resource managers and end-users to efficiently harness resources, mitigate threats and ensure safety. This paper outlines existing tools and explores the ongoing research that has the potential to convert the findings into operational services in the near- to midterm.
Finn Mielck, Rune Michaelis, H. Christian Hass, Sarah Hertel, Caroline Ganal, and Werner Armonies
Biogeosciences, 18, 3565–3577, https://doi.org/10.5194/bg-18-3565-2021, https://doi.org/10.5194/bg-18-3565-2021, 2021
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Marine sand mining is becoming more and more important to nourish fragile coastlines that face global change. We investigated the largest sand extraction site in the German Bight. The study reveals that after more than 35 years of mining, the excavation pits are still detectable on the seafloor while the sediment composition has largely changed. The organic communities living in and on the seafloor were strongly decimated, and no recovery is observable towards previous conditions.
France Van Wambeke, Elvira Pulido, Philippe Catala, Julie Dinasquet, Kahina Djaoudi, Anja Engel, Marc Garel, Sophie Guasco, Barbara Marie, Sandra Nunige, Vincent Taillandier, Birthe Zäncker, and Christian Tamburini
Biogeosciences, 18, 2301–2323, https://doi.org/10.5194/bg-18-2301-2021, https://doi.org/10.5194/bg-18-2301-2021, 2021
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Michaelis–Menten kinetics were determined for alkaline phosphatase, aminopeptidase and β-glucosidase in the Mediterranean Sea. Although the ectoenzymatic-hydrolysis contribution to heterotrophic prokaryotic needs was high in terms of N, it was low in terms of C. This study points out the biases in interpretation of the relative differences in activities among the three tested enzymes in regard to the choice of added concentrations of fluorogenic substrates.
Katharine T. Bigham, Ashley A. Rowden, Daniel Leduc, and David A. Bowden
Biogeosciences, 18, 1893–1908, https://doi.org/10.5194/bg-18-1893-2021, https://doi.org/10.5194/bg-18-1893-2021, 2021
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Turbidity flows – underwater avalanches – are large-scale physical disturbances believed to have profound impacts on productivity and diversity of benthic communities in the deep sea. We reviewed published studies and found that current evidence for changes in productivity is ambiguous at best, but the influence on regional and local diversity is clearer. We suggest study design criteria that may lead to a better understanding of large-scale disturbance effects on deep-sea benthos.
Phillip Williamson, Hans-Otto Pörtner, Steve Widdicombe, and Jean-Pierre Gattuso
Biogeosciences, 18, 1787–1792, https://doi.org/10.5194/bg-18-1787-2021, https://doi.org/10.5194/bg-18-1787-2021, 2021
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The reliability of ocean acidification research was challenged in early 2020 when a high-profile paper failed to corroborate previously observed impacts of high CO2 on the behaviour of coral reef fish. We now know the reason why: the
replicatedstudies differed in many ways. Open-minded and collaborative assessment of all research results, both negative and positive, remains the best way to develop process-based understanding of the impacts of ocean acidification on marine organisms.
Michael Lintner, Bianca Lintner, Wolfgang Wanek, Nina Keul, and Petra Heinz
Biogeosciences, 18, 1395–1406, https://doi.org/10.5194/bg-18-1395-2021, https://doi.org/10.5194/bg-18-1395-2021, 2021
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Foraminifera are unicellular marine organisms that play an important role in the marine element cycle. Changes of environmental parameters such as salinity or temperature have a significant impact on the faunal assemblages. Our experiments show that changes in salinity immediately influence the foraminiferal activity. Also the light regime has a significant impact on carbon or nitrogen processing in foraminifera which contain no kleptoplasts.
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Short summary
Upwelling intensity along NW Africa varies on the interannual to decadal timescale. Understanding its changes is key for the prediction of future changes of CO2 sequestration in the northeastern Atlantic. Based on a multiyear (1988–2009) sediment trap experiment at the site CBmeso, fluxes and the species composition of the diatom assemblage are presented. Our data help in establishing the scientific basis for forecasting and modeling future states of this ecosystem and its decadal changes.
Upwelling intensity along NW Africa varies on the interannual to decadal timescale....
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