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  • Articles  (16)
  • 1
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    Megafauna community assessment of polymetallic-nodule fields with cameras: platform and methodology comparison (2020)
    In:  EPIC3Biogeosciences, 17(12), pp. 3115-3133, ISSN: 1726-4189
    Details
    Publication Date: 2021-01-26
    Description: With the mining of polymetallic nodules from the deep-sea seafloor once more evoking commercial interest, decisions must be taken on how to most efficiently regulate and monitor physical and community disturbance in these remote ecosystems. Image-based approaches allow non-destructive assessment of the abundance of larger fauna to be derived from survey data, with repeat surveys of areas possible to allow time series data collection. At the time of writing, key underwater imaging platforms commonly used to map seafloor fauna abundances are autonomous underwater vehicles (AUVs), remotely operated vehicles (ROVs) and towed camera “ocean floor observation systems” (OFOSs). These systems are highly customisable, with cameras, illumination sources and deployment protocols changing rapidly, even during a survey cruise. In this study, eight image datasets were collected from a discrete area of polymetallic-nodule-rich seafloor by an AUV and several OFOSs deployed at various altitudes above the seafloor. A fauna identification catalogue was used by five annotators to estimate the abundances of 20 fauna categories from the different datasets. Results show that, for many categories of megafauna, differences in image resolution greatly influenced the estimations of fauna abundance determined by the annotators. This is an important finding for the development of future monitoring legislation for these areas. When and if commercial exploitation of these marine resources commences, robust and verifiable standards which incorporate developing technological advances in camera-based monitoring surveys should be key to developing appropriate management regulations for these regions.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    Deep-sea biodiversity hatspots: Time-series image data acquisation from challenging ecosystems with affordable open source hardware and software (2020)
    In:  EPIC3Ocean Science Meeting, San Diego, California, USA
    Details
    Publication Date: 2021-07-01
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 3
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    Megafauna community assessment with cameras: Platform, annotator and methodology comparison (2020)
    In:  EPIC3Ocean Science Meeting, San Diego, California, USA
    Details
    Publication Date: 2021-03-25
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 4
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    Effects of climate change on methane emissions from seafloor sediments in the Arctic Ocean: A review (2016)
    In:  EPIC3Limnology & Oceanography
    Details
    Publication Date: 2016-06-07
    Description: 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.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Water column methanotrophy controlled by a rapid oceanographic switch (2015)
    NATURE PUBLISHING GROUP
    In:  EPIC3Nature Geoscience, NATURE PUBLISHING GROUP
    Details
    Publication Date: 2015-12-15
    Description: Large amounts of the greenhouse gas methane are released from the seabed but liberation of methane to the atmosphere is mitigated by aerobic methanotrophs in the water column. The size and activity of methanotrophic communities are thought to be mainly determined by nutrient and redox dynamics, but little is known about the effects of water mass transport. Here, we show that cold bottom waters at methane seeps west off Svalbard, which contained a large number of aerobic methanotrophs, were rapidly displaced by warmer waters with a considerably smaller methanotrophic community. This water mass exchange, caused by short-term variations of the West Spitsbergen Current strongly reduced methanotrophic activity. Currents are common at many methane seeps and could thus be a globally important control on methane oxidation in the water column.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
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    Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand (2011)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in FEMS Microbiology Ecology 77 (2011): 518-532, doi:10.1111/j.1574-6941.2011.01133.x.
    Description: Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low diversity was observed in sediments from an eroded basin seaward of the ridge and the community was dominated by uncultured members of the Burkholderiales. Chloroflexi/GNS and Deltaproteobacteria were abundant in sediments from a methane seep located landward of the ridge. Gas-charged and organic rich sediments further landward had the highest overall diversity. Surface sediments, with the exception of those from the basin, were dominated by Rhodobacterales sequences associated with organic matter deposition. Taxa related to the Desulfosarcina/Desulfococcus and the JS1 candidates were highly abundant at the sulfate-methane transition zone (SMTZ) at three sites. To determine how community structure was influenced by terrestrial, pelagic, and in situ substrates, sequence data were was statistically analyzed against geochemical data (e.g., sulfate, chloride, nitrogen, phosphorous, methane, bulk inorganic and organic carbon pools) using the Biota-Environmental matching procedure. Landward of the ridge, sulfate was among the most significant structuring factors. Seaward of the ridge, silica and ammonium were important structuring factors. Regardless of the transect location, methane was the principal structuring factor on SMTZ communities.
    Description: This work was supported by the Naval Research Laboratory Chemistry Division Young Investigator Program and the Office of Naval Research platform support program.
    Description: 2012-05-19
    Keywords: Bacteria ; AOM ; Marine sediment ; Methane sulfate ; 454-Pyrosequencing
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 7
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    Preliminary results from the RV Poseidon 419 expedition to the methane seepage area off West Spitzbergen, Arctic Ocean (2011)
    In:  EPIC3GC52A-06 presented at 2011 Fall Meeting, AGU, San Francisco, Calif., 5-9 Dec.
    Details
    Publication Date: 2019-07-17
    Description: AB: The methane seepage area off West Spitzbergen, which was first discovered in 2008, is reported to feature more than 250 gas bubbles release sites in water depth between 150 and 400 m. Because the depth zone overlaps with the boundary of gas hydrate stability and since this area has experienced a warming of the northward-flowing West Spitzbergen current by 1°C over the last 30 years, it has been speculated that the gas seepage is connected to recent gas hydrate dissociation. However, so far comprehensive biogeochemical studies, which could support this hypothesis, are lacking. In August 2011, we will conduct an expedition with the German RV Poseidon to explore the seafloor and water column in the vicinity of the gas seeps to search for physical, geochemical, biological, and geological characteristics that could provide information about the persistence of the gas seepage. In case the gas venting is caused by recent gas hydrate dissociation, we expect to find rather virgin sediments with respect to common cold-seep characteristics such as methanotrophic activity and the presence of chemosynthetic organisms and authigenic carbonates; whereas a full establishment of these features would support the idea of a long-lasting process. Anomalies in porewater characteristics provide further information about gas hydrate formation/dissociation dynamics. We will present preliminary results from the RV Poseidon expedition to provide fresh insights into this exciting research area. Data will includ
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 8
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    Observations of deep-sea fishes and mobile scavengers from the abyssal DISCOL experimental mining area (2019)
    In:  EPIC3Biogeosciences, 16(16), pp. 3133-3146, ISSN: 1726-4189
    Details
    Publication Date: 2019-10-23
    Description: Industrial interest in deep-sea mineral extraction began decades ago, and today it is at an all-time high, accelerated by global demand for metals. Several seafloor ecosystem disturbance experiments began in the 1970s, including the Disturbance and Recolonization experiment (DISCOL) conducted in the Peru Basin in 1989. A large seafloor disturbance was created by repeatedly ploughing the seafloor over an area of∼10.8 km2. Though a number of studies in abyssal mining regions have evaluated megafaunal biodiversity and ecosystem responses, few have included quantitative and detailed data on fishes or scavengers despite their ecological importance as top predators. We used towed camera transects (1989–1996, 2015) and baited camera data (1989–1992) to evaluate the fish community at the DISCOL site.The abyssal fish community included 16 taxa and was dominated by Ipnops meadi. Fish density was lower in ploughed habitat at 6 months and 3 years following disturbance but thereafter increased over time. Twenty-six years after disturbance there were no differences in overall total fish densi-ties between reference and experimental areas, but the dominant fish,I. meadi, still exhibited much lower densities in ploughed habitat, likely avoiding these areas and suggesting that the fish community remains affected after decades.At the scale of industrial mining, these results could trans-late to population-level effects. The scavenging community was dominated by eelpouts (Pachycaraspp.), hermit crabs (Probeebei mirabilis) and shrimp. The large contribution of hermit crabs appears to be unique amongst abyssal scavenger studies worldwide. The abyssal fish community at DISCOL was similar to that in the more northerly Clarion–Clipperton Zone (CCZ), though some species have only been observed at DISCOL thus far. Also, further species-level identifications are required to refine this assessment. Additional studies across the polymetallic nodule provinces of the Pacific are required to further evaluate the environmental drivers offish density, diversity and species biogeographies. This information will be important for the development of appropriate management plans aimed at minimizing human impact from deep-sea mining.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 9
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    Influence of wind speed and wind direction above the sea surface on the diffusive methane flux and the atmospheric methane concentration at the North Sea (2023)
    In:  EPIC3
    Details
    Publication Date: 2023-05-02
    Description: The estimations of the diffusive methane flux from the water phase into the atmosphere in coastal waters is relevant for a better estimate of the atmospheric greenhouse-gas budget. Unfortunately, so far, the numerical determination of the fluxes has a high level of uncertainty in coastal waters. To improve the estimation of coastal methane fluxes, not only a high temporal and spatial sampling resolution of the dissolved methane in the water are required. Besides, also the atmospheric methane concentration and the wind speed and wind direction above the surface is important. In most cases, these atmospheric data are obtained from near-by atmospheric and meteorologic monitoring stations. In this study, we measured wind speed, direction and atmospheric methane local directly on board of three research vessel cruising in the southern North Sea within the MOSES project and compared the effects of local versus remote measurements of these data on the flux data. In addition, using the wind direction and speed, we try to assess the origin of the atmospheric methane measured in the study area. Using these “improved” data sets, we discuss if local measurements of auxiliary data provide better insights in the determining factors of the methane flux, and thus also improve the regional aquatic methane budget.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 10
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    Integrating Data Science and Earth Science (2022)
    Springer
    In:  EPIC3Integrating Data Science and Earth Science, Cham, Switzerland, Springer, 148 p., ISBN: 978-3-030-99545-4, ISSN: 2191-589X
    Details
    Publication Date: 2022-07-23
    Description: This open access book presents the results of three years collaboration between earth scientists and data scientists, in developing and applying data science methods for scientific discovery. The book will be highly beneficial for other researchers at senior and graduate level, interested in applying visual data exploration, computational approaches and scientifc workflows.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Book , NonPeerReviewed
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