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  • 1
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    Sinking of Gelatinous Zooplankton Biomass Increases Deep Carbon Transfer Efficiency Globally (2019)
    AGU (American Geophysical Union) | Wiley
    In:  Global Biogeochemical Cycles, 33 (12). pp. 1764-1783.
    Details
    Publication Date: 2022-01-31
    Description: Gelatinous zooplankton (Cnidaria, Ctenophora, and Urochordata, namely, Thaliacea) are ubiquitous members of plankton communities linking primary production to higher trophic levels and the deep ocean by serving as food and transferring “jelly‐carbon” (jelly‐C) upon bloom collapse. Global biomass within the upper 200 m reaches 0.038 Pg C, which, with a 2–12 months life span, serves as the lower limit for annual jelly‐C production. Using over 90,000 data points from 1934 to 2011 from the Jellyfish Database Initiative as an indication of global biomass (JeDI: http://jedi.nceas.ucsb.edu, http://www.bco‐dmo.org/dataset/526852), upper ocean jelly‐C biomass and production estimates, organism vertical migration, jelly‐C sinking rates, and water column temperature profiles from GLODAPv2, we quantitatively estimate jelly‐C transfer efficiency based on Longhurst Provinces. From the upper 200 m production estimate of 0.038 Pg C year−1, 59–72% reaches 500 m, 46–54% reaches 1,000 m, 43–48% reaches 2,000 m, 32–40% reaches 3,000 m, and 25–33% reaches 4,500 m. This translates into ~0.03, 0.02, 0.01, and 0.01 Pg C year−1, transferred down to 500, 1,000, 2,000, and 4,500 m, respectively. Jelly‐C fluxes and transfer efficiencies can occasionally exceed phytodetrital‐based sediment trap estimates in localized open ocean and continental shelves areas under large gelatinous blooms or jelly‐C mass deposition events, but this remains ephemeral and transient in nature. This transfer of fast and permanently exported carbon reaching the ocean interior via jelly‐C constitutes an important component of the global biological soft‐tissue pump, and should be addressed in ocean biogeochemical models, in particular, at the local and regional scale.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    DOI: 10.1029/2019GB006265
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Divergent responses of Atlantic cod to ocean acidification and food limitation (2019)
    Wiley
    In:  Global Change Biology, 25 (3). pp. 839-849.
    Details
    Publication Date: 2022-01-31
    Description: In order to understand the effect of global change on marine fishes, it is imperative to quantify the effects on fundamental parameters such as survival and growth. Larval survival and recruitment of the Atlantic cod (Gadus morhua) were found to be heavily impaired by end-of-century levels of ocean acidification. Here, we analysed larval growth among 35–36 days old surviving larvae, along with organ development and ossification of the skeleton. We combined CO2treatments (ambient: 503 µatm, elevated: 1,179 µatm) with food availability in order to evaluate the effect of energy limitation in addition to the ocean acidification stressor. As expected, larval size (as a proxy for growth) and skeletogenesis were positively affected by high food availability. We found significant interactions between acidification and food availability. Larvae fed ad libitum showed little difference in growth and skeletogenesis due to the CO2 treatment. Larvae under energy limitation were significantly larger and had further developed skeletal structures in the elevated CO2 treatment compared to the ambient CO2 treatment. However, the elevated CO2 group revealed impairments in critically important organs, such as the liver, and had comparatively smaller functional gills indicating a mismatch between size and function. It is therefore likely that individual larvae that had survived acidification treatments will suffer from impairments later during ontogeny. Our study highlights important allocation trade-off between growth and organ development, which is critically important to interpret acidification effects on early life stages of fish.
    Type: Article , PeerReviewed
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    DOI: 10.1111/gcb.14554
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    The Weddell Gyre, Southern Ocean: present knowledge and future challenges (2019)
    Wiley
    In:  EPIC3Reviews of Geophysics, Wiley, 57, ISSN: 8755-1209
    Details
    Publication Date: 2019-08-01
    Description: The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures and presence of sea ice year‐round hamper field and remotely sensed measurements. We highlight the importance of winter and under‐ice conditions in the southern WG, the role that new technology will play to overcome present‐day sampling limitations, the importance of the WG connectivity to the low‐latitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an East‐West section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide long‐term data to determine trends and will improve representation of processes for regional, Antarctic‐wide and global modeling efforts – thereby enhancing predictions of the WG in global ocean circulation and climate.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 4
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    Interplay of subduction tectonics, sedimentation, and carbon cycling (2019)
    AGU | Wiley
    In:  Geochemistry, Geophysics, Geosystems, 20 (11). pp. 4939-4955.
    Details
    Publication Date: 2022-01-31
    Description: Distinct differences were observed in geochemical signatures in sediments from two sites drilled in the upper plate of the Costa Rica margin during Integrated Ocean Drilling Program (IODP) Expedition 334. The upper 80 m at Site U1379, located on the outer shelf, show pore water non‐steady state conditions characteristic of a declining methane flux. These contrast with analyses of the upper sediment layers at the middle slope site (U1378) that reflect steady state conditions. Distinct carbonate‐rich horizons up to 11 meters thick were recovered between 63 and 310 meters below seafloor at Site U1379 but were not found at Site U1378. The carbonates and dissolved inorganic carbon from Site U1379 have a depleted carbon stable isotope signal (up to ‐25‰) that indicates anaerobic methane oxidation. This inference is further supported by distinct δ34S‐pyrite and magnetic susceptibility records that reveal fluctuations of the sulfate‐methane transition in response to methane flux variations. Tectonic reconstructions of this margin document a marked subsidence event after arrival of the Cocos Ridge, 2.2 ± 0.2 million years ago (Ma), followed by increased sedimentation rates and uplift. As the seafloor at Site U1379 rose from ~2000 m to the present water depth of ~126 m, the site moved out of the gas hydrate stability zone (GHSZ) at ~1.1 Ma, triggering upward methane advection, methane oxidation, and the onset of massive carbonate formation. Younger carbonate occurrences and the non‐steady state pore profiles at Site U1379 reflect continued episodic venting likely modulated by changes in the underlying methane reservoir.
    Type: Article , PeerReviewed
    Format: text
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    DOI: 10.1029/2019GC008613
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges (2019)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2023-03-09
    Description: The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures, and presence of sea ice year‐round hamper field and remotely sensed measurements. We highlight the importance of winter and under‐ice conditions in the southern WG, the role that new technology will play to overcome present‐day sampling limitations, the importance of the WG connectivity to the low‐latitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an East‐West section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide long‐term data to determine trends and will improve representation of processes for regional, Antarctic‐wide, and global modeling efforts—thereby enhancing predictions of the WG in global ocean circulation and climate.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Pacing of Red Sea Deep Water Renewal During the Last Centuries (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 46(8), pp. 4413-4420, ISSN: 0094-8276
    Details
    Publication Date: 2019-10-07
    Description: The Red Sea is a deep marine basin often considered as small‐scale version of the global ocean. Hydrographic observations and ocean‐atmosphere modeling indicate Red Sea deep water was episodically renewed by wintertime open‐ocean deep convections during 1982–2001, suggesting a renewal time on the order of a decade. However, the long‐term pacing of Red Sea deep water renewals is largely uncertain. We use an annually resolved coral oxygen isotope record of winter surface water conditions to show that the late twentieth century deep water renewals were probably unusual in the context of the preceding ~100 years. More frequent major events are detected during the late Little Ice Age, particularly during the early nineteenth century characterized by large tropical volcanic eruptions. We conclude that Red Sea deep water renewal time is on the order of a decade up to a century, depending on the mean climatic conditions and large‐scale interannual climate forcing.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 7
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    PIRATA: A Sustained Observing System for Tropical Atlantic Climate Research and Forecasting (2019)
    AGU (American Geophysical Union) | Wiley
    In:  Earth and Space Science, 6 (4). pp. 577-616.
    Details
    Publication Date: 2022-01-31
    Description: Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) is a multinational program initiated in 1997 in the tropical Atlantic to improve our understanding and ability to predict ocean-atmosphere variability. PIRATA consists of a network of moored buoys providing meteorological and oceanographic data transmitted in real time to address fundamental scientific questions as well as societal needs. The network is maintained through dedicated yearly cruises, which allow for extensive complementary shipboard measurements and provide platforms for deployment of other components of the Tropical Atlantic Observing System. This paper describes network enhancements, scientific accomplishments and successes obtained from the last 10 years of observations, and additional results enabled by cooperation with other national and international programs. Capacity building activities and the role of PIRATA in a future Tropical Atlantic Observing System that is presently being optimized are also described.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1029/2018EA000428
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 8
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    How to select networks of marine protected areas for multiple species with different dispersal strategies (2015)
    Wiley
    In:  Diversity and Distributions, 22 (2). pp. 161-173.
    Details
    Publication Date: 2016-02-26
    Description: Aim: To develop and test theory based on connectivity to identify optimal networks of marine protected areas (MPAs) that protect multiple species with a range of dispersal strategies. Location: The eastern North Sea in the Atlantic Ocean. Methods: Theory of finding optimal MPA network is based on eigenvalue perturbation theory applied to population connectivity. Previous theory is here extended to the persistence of multiple species by solving a maximization problem with constraints, which identifies an optimal consensus network of MPAs. The theory is applied to two test cases within a 120,000 km2 area in the North Sea where connectivity was estimated with a biophysical model. In a realistic case, the theory is applied to the protection of rocky-reef habitats, where the biophysical model is parameterized with realistic dispersal traits for key species. Theoretical predictions of optimal networks were validated with a simple metapopulation model. Persistence of optimal consensus MPA networks is compared to randomly selected networks as well as to the existing MPA network. Results: Despite few overlapping MPA sites for the optimal networks based on single dispersal strategies, the consensus network for multiple dispersal strategies performed well for 3 of 4 contrasting strategies even without user-defined constraints. In the test with five realistic dispersal strategies, representing a community on threatened rocky reefs, the consensus network performed equally well compared to solutions for single species. Different dispersal strategies were also protected jointly across the MPA network (93% of sites), in contrast to simulations of the existing MPA network (2% of sites). Consensus networks based on connectivity were significantly more efficient compared to existing MPAs. Main conclusions: Our findings suggest that the new theoretic framework can identify a consensus MPA network that protects a whole community containing species with multiple dispersal strategies.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/ddi.12394
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    The Mechanism of Methane Gas Migration Through the Gas Hydrate Stability Zone: Insights From Numerical Simulations (2019)
    AGU (American Geophysical Union) | Wiley
    In:  Journal of Geophysical Research: Solid Earth, 124 (5). pp. 4399-4427.
    Details
    Publication Date: 2022-01-31
    Description: Free gas migration through the gas hydrate stability zone (GHSZ) and subsequent gas seepage at the seabed are characteristic features in marine gas hydrate provinces worldwide. The biogenic or thermogenic gas is typically transported along faults from deeper sediment strata to the GHSZ. Several mechanisms have been proposed to explain free gas transport through the GHSZ. While inhibition of hydrate formation by elevated salinities and temperatures have been addressed previously in studies simulating unfocused, area-wide upward advection of gas, which is not adequately supported by field observations, the role of focused gas flow through chimney-like structures has been underappreciated in this context. Our simulations suggest that gas migration through the GHSZ is, fundamentally, a result of methane gas supply in excess of its consumption by hydrate formation. The required high gas flux is driven by local overpressure, built up from gas accumulating below the base of the GHSZ that fractures the overburden when exceeding a critical pressure, thereby creating the chimney-like migration pathway. Initially rapid hydrate formation raises the temperature in the chimney structure, thereby facilitating further gas transport through the GHSZ. As a consequence, high hydrate saturations form preferentially close to the seafloor, where temperatures drop to bottom water values, producing a prominent subsurface salinity peak. Over time, hydrates form at a lower rate throughout the chimney structure, while initial temperature elevation and salinity peak dissipate. Thus, our simulations suggest that the near-surface salinity peak and elevated temperatures are a result of transient high-flux gas migration through the GHSZ.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1029/2019JB017417
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Explaining participation rates in recreational fishing across industrialised countries (2015)
    Wiley
    In:  Fisheries Management and Ecology, 22 (1). pp. 45-55.
    Details
    Publication Date: 2017-01-06
    Description: On average, 10.52% of the total population was found to fish for recreation across the industrialised world (N = 27 countries), amounting to an estimated 118 million (95% confidence interval 81–154 million) people in North America, Europe and Oceania. Participation rates declined with population density and gross domestic product, indicating a negative effect of urbanisation and post-modernisation on fishing interest. Participation rates also declined with increasing median age, average household size and unemployment rate, suggesting resource limitation to constrain participation in fishing. By contrast, two indicators of the cultural importance of fish (fish landings and per capita fish consumption) and an indicator of perceived need for leisure (weekly working hours) were positively correlated with fishing participation. Based on these findings, which explained 60% of the variance in fishing participation across the industrialised world, reduced fishing interest is to be expected with post-industrialisation. Dedicated management and marketing intervention is needed to reverse the track of diminishing fishing interest in industrialised countries.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/fme.12075
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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