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  • 1
    Online Resource
    Online Resource
    Digging deep: lessons learned from meiofaunal responses to a disturbance experiment in the Clarion-Clipperton Zone
    Springer Science and Business Media LLC ; 2023
    In:  Marine Biodiversity Vol. 53, No. 4 ( 2023-08)
    Details
    In: Marine Biodiversity, Springer Science and Business Media LLC, Vol. 53, No. 4 ( 2023-08)
    Abstract: The deep-sea mining industry is currently at a point where large-sale, commercial polymetallic nodule exploitation is becoming a more realistic scenario. At the same time, certain aspects such as the spatiotemporal scale of impacts, sediment plume dispersion and the disturbance-related biological responses remain highly uncertain. In this paper, findings from a small-scale seabed disturbance experiment in the German contract area (Clarion-Clipperton Zone, CCZ) are described, with a focus on the soft-sediment ecosystem component. Despite the limited spatial scale of the induced disturbance on the seafloor, this experiment allowed us to evaluate how short-term ( 〈  1 month) soft-sediment changes can be assessed based on sediment characteristics (grain size, nutrients and pigments) and metazoan meiofaunal communities (morphological and metabarcoding analyses). Furthermore, we show how benthic measurements can be combined with numerical modelling of sediment transport to enhance our understanding of meiofaunal responses to increased sedimentation levels. The lessons learned within this study highlight the major issues of current deep-sea mining-related ecological research such as deficient baseline knowledge, unrepresentative impact intensity of mining simulations and challenges associated with sampling trade-offs (e.g., replication).
    Type of Medium: Online Resource
    ISSN: 1867-1616 , 1867-1624
    URL: Article
    DOI: 10.1007/s12526-023-01353-0
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
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    detail.hit.zdb_id: 2493558-X
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  • 2
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    Online Resource
    Linked sediment and water‐column methanotrophy at a man‐made gas blowout in the North Sea: Implications for methane budgeting in seasonally stratified shallow seas
    Wiley ; 2016
    In:  Limnology and Oceanography Vol. 61, No. S1 ( 2016-11)
    Details
    In: Limnology and Oceanography, Wiley, Vol. 61, No. S1 ( 2016-11)
    Abstract: Large quantities of the greenhouse gas methane (CH 4 ) are stored in the seafloor. The flux of CH 4 from the sediments into the water column and finally to the atmosphere is mitigated by a series of microbial methanotrophic filter systems of unknown efficiency at highly active CH 4 ‐release sites in shallow marine settings. Here, we studied CH 4 ‐oxidation and the methanotrophic community at a high‐CH 4 ‐flux site in the northern North Sea (well 22/4b), where CH 4 is continuously released since a blowout in 1990. Vigorous bubble emanation from the seafloor and strongly elevated CH 4 concentrations in the water column (up to 42 µM) indicated that a substantial fraction of CH 4 bypassed the highly active (up to ∼2920 nmol cm −3 d −1 ) zone of anaerobic CH 4 ‐oxidation in sediments. In the water column, we measured rates of aerobic CH 4 ‐oxidation (up to 498 nM d −1 ) that were among the highest ever measured in a marine environment and, under stratified conditions, have the potential to remove a significant part of the uprising CH 4 prior to evasion to the atmosphere. An unusual dominance of the water‐column methanotrophs by Type II methane‐oxidizing bacteria (MOB) is partially supported by recruitment of sedimentary MOB, which are entrained together with sediment particles in the CH 4 bubble plume. Our study thus provides evidence that bubble emission can be an important vector for the transport of sediment‐borne microbial inocula, aiding in the rapid colonization of the water column by methanotrophic communities and promoting their persistence close to highly active CH 4 point sources.
    Type of Medium: Online Resource
    ISSN: 0024-3590 , 1939-5590
    URL: Issue
    URL: Article
    DOI: 10.1002/lno.v61.S1
    DOI: 10.1002/lno.10388
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
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    SSG: 14
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  • 3
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    Online Resource
    Mind the seafloor
    American Association for the Advancement of Science (AAAS) ; 2018
    In:  Science Vol. 359, No. 6371 ( 2018-01-05), p. 34-36
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 359, No. 6371 ( 2018-01-05), p. 34-36
    Abstract: As human use of rare metals has diversified and risen with global development, metal ore deposits from the deep ocean floor are increasingly seen as an attractive future resource. Japan recently completed the first successful test for zinc extraction from the deep seabed, and the number of seafloor exploration licenses filed at the International Seabed Authority (ISA) has tripled in the past 5 years. Seafloor-mining equipment is being tested, and industrial-scale production in national waters could start in a few years. We call for integrated scientific studies of global metal resources, the fluxes and fates of metal uses, and the ecological footprints of mining on land and in the sea, to critically assess the risks of deep-sea mining and the chances for alternative technologies. Given the increasing scientific evidence for long-lasting impacts of mining on the abyssal environment, precautionary regulations for commercial deep-sea mining are essential to protect marine ecosystems and their biodiversity.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.aap7301
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2018
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
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  • 4
    Online Resource
    Online Resource
    Resilience of benthic deep-sea fauna to mining activities
    Elsevier BV ; 2017
    In:  Marine Environmental Research Vol. 129 ( 2017-08), p. 76-101
    Details
    In: Marine Environmental Research, Elsevier BV, Vol. 129 ( 2017-08), p. 76-101
    Type of Medium: Online Resource
    ISSN: 0141-1136
    URL: Article
    DOI: 10.1016/j.marenvres.2017.04.010
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
    detail.hit.zdb_id: 437280-3
    detail.hit.zdb_id: 1502505-6
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  • 5
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    Online Resource
    Evidence of eddy-related deep-ocean current variability in the northeast tropical Pacific Ocean induced by remote gap winds
    Copernicus GmbH ; 2020
    In:  Biogeosciences Vol. 17, No. 24 ( 2020-12-23), p. 6527-6544
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 17, No. 24 ( 2020-12-23), p. 6527-6544
    Abstract: Abstract. There has been a steady increase in interest in mining of deep-sea minerals in the Clarion–Clipperton Zone (CCZ) in the eastern Pacific Ocean during the last decade. This region is known to be one of the most eddy-rich regions in the world ocean. Typically, mesoscale eddies are generated by intense wind bursts channeled through gaps in the Sierra Madre mountains in Central America. Here, we use a combination of satellite and in situ observations to evaluate the relationship between deep-sea current variability in the region of potential future mining and eddy kinetic energy (EKE) in the vicinity of gap winds. A geometry-based eddy detection algorithm has been applied to altimetry sea surface height data for a period of 24 years, from 1993 to 2016, in order to analyze the main characteristic parameters and the spatiotemporal variability of mesoscale eddies in the northeast tropical Pacific Ocean (NETP). Significant differences between the characteristics of eddies with different polarity (cyclonic vs. anticyclonic) were found. For eddies with lifetimes longer than 1 d, cyclonic polarity is more common than anticyclonic rotation. However, anticyclonic eddies are larger in size, show stronger vorticity, and survive longer in the ocean than cyclonic eddies (often 90 d or more). Besides the polarity of eddies, the location of eddy formation should be taken into consideration when investigating the impacted deep-ocean region as we found eddies originating from the Tehuantepec (TT) gap winds lasting longer in the ocean and traveling farther distances in a different direction compared to eddies produced by the Papagayo (PP) gap winds. Long-lived anticyclonic eddies generated by the TT gap winds are observed to travel distances up to 4500 km offshore, i.e., as far as west of 110∘ W. EKE anomalies observed in the surface of the central ocean at distances of ca. 2500 km from the coast correlate with the seasonal variability of EKE in the region of the TT gap winds with a time lag of 5–6 months. A significant seasonal variability of deep-ocean current velocities at water depths of 4100 m was observed in multiple-year time series data, likely reflecting the energy transfer of the surface EKE generated by the gap winds to the deep ocean. Furthermore, the influence of mesoscale eddies on deep-ocean currents is examined by analyzing the deep-ocean current measurements when an anticyclonic eddy crosses the study region. Our findings suggest that despite the significant modulation of dominant current directions driven by the bottom-reaching eddy, the current magnitude intensification was not strong enough to trigger local sediment resuspension in this region. A better insight into the annual variability of ocean surface mesoscale activity in the CCZ and its effects on deep-ocean current variability can be of great help to mitigate the impact of future potential deep-sea mining activities on the benthic ecosystem. On an interannual scale, a significant relationship between cyclonic eddy characteristics and El Niño–Southern Oscillation (ENSO) was found, whereas a weaker correlation was detected for anticyclonic eddies.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-17-6527-2020
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2158181-2
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  • 6
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    Online Resource
    Small-scale heterogeneity of trace metals including rare earth elements and yttrium in deep-sea sediments and porewaters of the Peru Basin, southeastern equatorial Pacific
    Copernicus GmbH ; 2019
    In:  Biogeosciences Vol. 16, No. 24 ( 2019-12-20), p. 4829-4849
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 16, No. 24 ( 2019-12-20), p. 4829-4849
    Abstract: Abstract. Due to its remoteness, the deep-sea floor remains an understudied ecosystem of our planet. The patchiness of existing data sets makes it difficult to draw conclusions about processes that apply to a wider area. In our study we show how different settings and processes determine sediment heterogeneity on small spatial scales. We sampled solid phase and porewater from the upper 10 m of an approximately 7.4×13 km2 area in the Peru Basin, in the southeastern equatorial Pacific Ocean, at 4100 m water depth. Samples were analyzed for trace metals, including rare earth elements and yttrium (REY), as well as for particulate organic carbon (POC), CaCO3, and nitrate. The analyses revealed the surprisingly high spatial small-scale heterogeneity of the deep-sea sediment composition. While some cores have the typical green layer from Fe(II) in the clay minerals, this layer is missing in other cores, i.e., showing a tan color associated with more Fe(III) in the clay minerals. This is due to varying organic carbon contents: nitrate is depleted at 2–3 m depth in cores with higher total organic carbon contents but is present throughout cores with lower POC contents, thus inhibiting the Fe(III)-to-Fe(II) reduction pathway in organic matter degradation. REY show shale-normalized (SN) patterns similar to seawater, with a relative enrichment of heavy REY over light REY, positive LaSN anomaly, negative CeSN anomaly, and positive YSN anomaly and correlate with the Fe-rich clay layer and, in some cores, also correlate with P. We therefore propose that Fe-rich clay minerals, such as nontronite, as well as phosphates, are the REY-controlling phases in these sediments. Variability is also seen in dissolved Mn and Co concentrations between sites and within cores, which might be due to dissolving nodules in the suboxic sediment, as well as in concentration peaks of U, Mo, As, V, and Cu in two cores, which might be related to deposition of different material at lower-lying areas or precipitation due to shifting redox boundaries.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.5194/bg-16-4829-2019
    DOI: 10.5194/bg-16-4829-2019-supplement
    DOI: 10.5194/bg-16-4829-2019-corrigendum
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2019
    detail.hit.zdb_id: 2158181-2
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  • 7
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    Online Resource
    Assessing the temporal scale of deep-sea mining impacts on sediment biogeochemistry
    Copernicus GmbH ; 2020
    In:  Biogeosciences Vol. 17, No. 10 ( 2020-05-26), p. 2767-2789
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 17, No. 10 ( 2020-05-26), p. 2767-2789
    Abstract: Abstract. Deep-sea mining for polymetallic nodules is expected to have severe environmental impacts because not only nodules but also benthic fauna and the upper reactive sediment layer are removed through the mining operation and blanketed by resettling material from the suspended sediment plume. This study aims to provide a holistic assessment of the biogeochemical recovery after a disturbance event by applying prognostic simulations based on an updated diagenetic background model and validated against novel data on microbiological processes. It was found that the recovery strongly depends on the impact type; complete removal of the reactive surface sediment reduces benthic release of nutrients over centuries, while geochemical processes after resuspension and mixing of the surface sediment are near the pre-impact state 1 year after the disturbance. Furthermore, the geochemical impact in the DISturbance and reCOLonization (DISCOL) experiment area would be mitigated to some degree by a clay-bound Fe(II)-reaction layer, impeding the downward diffusion of oxygen, thus stabilizing the redox zonation of the sediment during transient post-impact recovery. The interdisciplinary (geochemical, numerical and biological) approach highlights the closely linked nature of benthic ecosystem functions, e.g. through bioturbation, microbial biomass and nutrient fluxes, which is also of great importance for the system recovery. It is, however, important to note that the nodule ecosystem may never recover to the pre-impact state without the essential hard substrate and will instead be dominated by different faunal communities, functions and services.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-17-2767-2020
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2158181-2
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  • 8
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    Impact of small-scale disturbances on geochemical conditions, biogeochemical processes and element fluxes in surface sediments of the eastern Clarion–Clipperton Zone, Pacific Ocean
    Copernicus GmbH ; 2020
    In:  Biogeosciences Vol. 17, No. 4 ( 2020-02-28), p. 1113-1131
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 17, No. 4 ( 2020-02-28), p. 1113-1131
    Abstract: Abstract. The thriving interest in harvesting deep-sea mineral resources, such as polymetallic nodules, calls for environmental impact studies and, ultimately, for regulations for environmental protection. Industrial-scale deep-sea mining of polymetallic nodules most likely has severe consequences for the natural environment. However, the effects of mining activities on deep-sea ecosystems, sediment geochemistry and element fluxes are still poorly understood. Predicting the environmental impact is challenging due to the scarcity of environmental baseline studies as well as the lack of mining trials with industrial mining equipment in the deep sea. Thus, currently we have to rely on small-scale disturbances simulating deep-sea mining activities as a first-order approximation to study the expected impacts on the abyssal environment. Here, we investigate surface sediments in disturbance tracks of seven small-scale benthic impact experiments, which have been performed in four European contract areas for the exploration of polymetallic nodules in the Clarion–Clipperton Zone (CCZ) in the NE Pacific. These small-scale disturbance experiments were performed 1 d to 37 years prior to our sampling program in the German, Polish, Belgian and French contract areas using different disturbance devices. We show that the depth distribution of solid-phase Mn in the upper 20 cm of the sediments in the CCZ provides a reliable tool for the determination of the disturbance depth, which has been proposed in a previous study from the SE Pacific (Paul et al., 2018). We found that the upper 5–15 cm of the sediments was removed during various small-scale disturbance experiments in the different exploration contract areas. Transient transport-reaction modeling for the Polish and German contract areas reveals that the removal of the surface sediments is associated with the loss of the reactive labile total organic carbon (TOC) fraction. As a result, oxygen consumption rates decrease significantly after the removal of the surface sediments, and, consequently, oxygen penetrates up to 10-fold deeper into the sediments, inhibiting denitrification and Mn(IV) reduction. Our model results show that the return to steady-state geochemical conditions after the disturbance is controlled by diffusion until the reactive labile TOC fraction in the surface sediments is partly re-established and the biogeochemical processes commence. While the re-establishment of bioturbation is essential, steady-state geochemical conditions are ultimately controlled by the delivery rate of organic matter to the seafloor. Hence, under current depositional conditions, new steady-state geochemical conditions in the sediments of the CCZ are reached only on a millennium scale even for these small-scale disturbances simulating deep-sea mining activities.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-17-1113-2020
    DOI: 10.5194/bg-17-1113-2020-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2158181-2
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  • 9
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    Online Resource
    The Microwave Spectrum and Molecular Structure of the Hydrogen-Bonded Aniline–Methanol Complex
    Elsevier BV ; 1999
    In:  Journal of Molecular Spectroscopy Vol. 198, No. 2 ( 1999-12), p. 263-277
    Details
    In: Journal of Molecular Spectroscopy, Elsevier BV, Vol. 198, No. 2 ( 1999-12), p. 263-277
    Type of Medium: Online Resource
    ISSN: 0022-2852
    URL: Article
    DOI: 10.1006/jmsp.1999.7969
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1999
    detail.hit.zdb_id: 1469771-3
    SSG: 11
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  • 10
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    Effects of climate change on methane emissions from seafloor sediments in the Arctic Ocean: A review
    Wiley ; 2016
    In:  Limnology and Oceanography Vol. 61, No. S1 ( 2016-11)
    Details
    In: Limnology and Oceanography, Wiley, Vol. 61, No. S1 ( 2016-11)
    Abstract: Large quantities of methane are stored in hydrates and permafrost within shallow marine sediments in the Arctic Ocean. These reservoirs are highly sensitive to climate warming, but the fate of methane released from sediments is uncertain. Here, we review the principal physical and biogeochemical processes that regulate methane fluxes across the seabed, the fate of this methane in the water column, and potential for its release to the atmosphere. We find that, at present, fluxes of dissolved methane are significantly moderated by anaerobic and aerobic oxidation of methane. If methane fluxes increase then a greater proportion of methane will be transported by advection or in the gas phase, which reduces the efficiency of the methanotrophic sink. Higher freshwater discharge to Arctic shelf seas may increase stratification and inhibit transfer of methane gas to surface waters, although there is some evidence that increased stratification may lead to warming of sub‐pycnocline waters, increasing the potential for hydrate dissociation. Loss of sea‐ice is likely to increase wind speeds and sea‐air exchange of methane will consequently increase. Studies of the distribution and cycling of methane beneath and within sea ice are limited, but it seems likely that the sea‐air methane flux is higher during melting in seasonally ice‐covered regions. Our review reveals that increased observations around especially the anaerobic and aerobic oxidation of methane, bubble transport, and the effects of ice cover, are required to fully understand the linkages and feedback pathways between climate warming and release of methane from marine sediments.
    Type of Medium: Online Resource
    ISSN: 0024-3590 , 1939-5590
    URL: Issue
    URL: Article
    DOI: 10.1002/lno.v61.S1
    DOI: 10.1002/lno.10307
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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