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  • 1
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    Composition, buoyancy regulation and fate of ice algal aggregates in the central Arctic Ocean (2014)
    Public Library of Science
    In:  PLoS ONE, 9 (9). e107452.
    Details
    Publication Date: 2015-03-12
    Description: Sea-ice diatoms are known to accumulate in large aggregates in and under sea ice and in melt ponds. There is recent evidence from the Arctic that such aggregates can contribute substantially to particle export when sinking from the ice. The role and regulation of microbial aggregation in the highly seasonal, nutrient- and light-limited Arctic sea-ice ecosystem is not well understood. To elucidate the mechanisms controlling the formation and export of algal aggregates from sea ice, we investigated samples taken in late summer 2011 and 2012, during two cruises to the Eurasian Basin of the Central Arctic Ocean. Spherical aggregates densely packed with pennate diatoms, as well as filamentous aggregates formed by Melosira arctica showed sign of different stages of degradation and physiological stoichiometries, with carbon to chlorophyll a ratios ranging from 110 to 66700, and carbon to nitrogen molar ratios of 8–35 and 9–40, respectively. Sub-ice algal aggregate densities ranged between 1 and 17 aggregates m−2, maintaining an estimated net primary production of 0.4–40 mg C m−2 d−1, and accounted for 3–80% of total phototrophic biomass and up to 94% of local net primary production. A potential factor controlling the buoyancy of the aggregates was light intensity, regulating photosynthetic oxygen production and the amount of gas bubbles trapped within the mucous matrix, even at low ambient nutrient concentrations. Our data-set was used to evaluate the distribution and importance of Arctic algal aggregates as carbon source for pelagic and benthic communities.
    Type: Article , PeerReviewed
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  • 2
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    Bacterial sulfur cycling shapes microbial communities in surface sediments of an ultramafic hydrothermal vent field (2011)
    Wiley
    In:  Environmental Microbiology, 13 (10). pp. 2633-2648.
    Details
    Publication Date: 2018-09-12
    Description: The ultramafic-hosted Logatchev hydrothermal field (LHF) is characterized by vent fluids, which are enriched in dissolved hydrogen and methane compared with fluids from basalt-hosted systems. Thick sediment layers in LHF are partly covered by characteristic white mats. In this study, these sediments were investigated in order to determine biogeochemical processes and key organisms relevant for primary production. Temperature profiling at two mat-covered sites showed a conductive heating of the sediments. Elemental sulfur was detected in the overlying mat and metal-sulfides in the upper sediment layer. Micro-profiles revealed an intensive hydrogen sulfide flux from deeper sediment layers. Fluorescence in situ hybridization showed that filamentous and vibrioid, Arcobacter-related Epsilonproteobacteria dominated the overlying mats. This is in contrast to sulfidic sediments in basalt-hosted fields where mats of similar appearance are composed of large sulfur-oxidizing Gammaproteobacteria. Epsilonproteobacteria (7-21%) and Deltaproteobacteria (20-21%) were highly abundant in the surface sediment layer. The physiology of the closest cultivated relatives, revealed by comparative 16S rRNA sequence analysis, was characterized by the capability to metabolize sulfur components. High sulfate reduction rates as well as sulfide depleted in (34)S further confirmed the importance of the biogeochemical sulfur cycle. In contrast, methane was found to be of minor relevance for microbial life in mat-covered surface sediments. Our data indicate that in conductively heated surface sediments microbial sulfur cycling is the driving force for bacterial biomass production although ultramafichosted systems are characterized by fluids with high levels of dissolved methane and hydrogen
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  • 3
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    Potential impact of CCS leakage on marine communities (2014)
    Plymouth Marine Laboratory
    In:  ECO2 Deliverable, D4.1 . Plymouth Marine Laboratory, 86 pp.
    Details
    Publication Date: 2019-03-11
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 4
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    Continuous Software Engineering for Designing and Operating an Autonomous Ocean Observation System (2019)
    In:  [Poster] In: German Research Software Engineering Conference, 04.-06.06.2019, Potsdam, Germany .
    Details
    Publication Date: 2019-09-23
    Description: The ocean is the largest ecosystem on earth, facing dramatic changes like deoxygenation, warming, acidification, and contamination by industrial pollution to name a few. To resolve major changes of the marine realm in space and time a highly cooperating network of robotic and synchronized autonomous multiple sensor systems is needed. In 2018 the Helmholtz Centres DLR, AWI, KIT, and GEOMAR formed a research alliance to investigate how robotic networks can be build to autonomously explore these environments. The vision of this Helmholtz Future Project ARCHES, is a network of heterogeneous, autonomous and interconnected robotic systems. To operate the network we develop an underwater communication framework. The centrepiece of our framework is the middleware Robot Operating System (ROS). ROS provides us interfaces and services to develop a microservice architecture with loosely coupled nodes. This project is designed using a continuous delivery workflow with automatic testing and releasing of software. We containerize the entire framework using Docker. Hence, we easily control all dependencies of our nodes, and by running the nodes in separate sandboxes, they cannot crash the entire robotic system upon failure of a single system component.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 5
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    OceanSITES Innovation Report (2019)
    AtlantOS
    In:  AtlantOS Deliverable, D3.17 . AtlantOS, 24 pp.
    Details
    Publication Date: 2021-05-19
    Description: Innovation and improvement report on the extension of capabilities to measure emerging EOVs including metagenomics across different observational platforms with links to MicroB3 best practice.
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 6
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    From single autonomous robots toward cooperative robotic interactions for future planetary exploration missions (2018)
    In:  [Paper] In: 69. International Astronautical Congress (IAC), 01.-05.10.2018, Bremen, Germany ; pp. 1-8 .
    Details
    Publication Date: 2019-09-23
    Description: Mobile robotics will play a key role in future space, ocean and deep sea exploration activities. Besides the actual development of the robotic systems, the different ways of commanding those systems, using technologies varying from teleoperation with the human in the loop, through shared autonomy towards highly autonomous systems, will be the main challenges of these missions. This paper describes the robotic activities of the DLR institutions within the Helmholtz projects ROBEX and ARCHES, dealing with robots for autonomous space and ocean exploration applications. Furthermore, it describes the challenges, the overlap and the synergies of those domains, the different approaches of operating robots from far distances in extreme environments and gives an outlook on future mission possibilities.
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  • 7
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    Eruption of a deep-sea mud volcano triggers rapid sediment movement (2014)
    Nature Publishing Group
    In:  Nature Communications, 5 (5385).
    Details
    Publication Date: 2019-07-10
    Description: Submarine mud volcanoes are important sources of methane to the water column. However, the temporal variability of their mud and methane emissions is unknown. Methane emissions were previously proposed to result from a dynamic equilibrium between upward migration and consumption at the seabed by methane-consuming microbes. Here we show non-steady-state situations of vigorous mud movement that are revealed through variations in fluid flow, seabed temperature and seafloor bathymetry. Time series data for pressure, temperature, pH and seafloor photography were collected over 431 days using a benthic observatory at the active Hakon Mosby Mud Volcano. We documented 25 pulses of hot subsurface fluids, accompanied by eruptions that changed the landscape of the mud volcano. Four major events triggered rapid sediment uplift of more than a metre in height, substantial lateral flow of muds at average velocities of 0.4m per day, and significant emissions of methane and CO2 from the seafloor.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 8
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    Oxygen fluxes beneath Arctic land-fast ice and pack ice: towards estimates of ice productivity (2018)
    Springer
    In:  Polar Biology, 41 (10). pp. 2119-2134.
    Details
    Publication Date: 2021-02-08
    Description: Sea-ice ecosystems are among the most extensive of Earth’s habitats; yet its autotrophic and heterotrophic activities remain poorly constrained. We employed the in situ aquatic eddy-covariance (AEC) O2 flux method and laboratory incubation techniques (H14CO3−, [3H] thymidine and [3H] leucine) to assess productivity in Arctic sea-ice using different methods, in conditions ranging from land-fast ice during winter, to pack ice within the central Arctic Ocean during summer. Laboratory tracer measurements resolved rates of bacterial C demand of 0.003–0.166 mmol C m−2 day−1 and primary productivity rates of 0.008–0.125 mmol C m−2 day−1 for the different ice floes. Pack ice in the central Arctic Ocean was overall net autotrophic (0.002–0.063 mmol C m−2 day−1), whereas winter land-fast ice was net heterotrophic (− 0.155 mmol C m−2 day−1). AEC measurements resolved an uptake of O2 by the bottom-ice environment, from ~ − 2 mmol O2 m−2 day−1 under winter land-fast ice to~ − 6 mmol O2 m−2 day−1 under summer pack ice. Flux of O2-deplete meltwater and changes in water flow velocity masked potential biological-mediated activity. AEC estimates of primary productivity were only possible at one study location. Here, productivity rates of 1.3 ± 0.9 mmol O2 m−2 day−1, much larger than concurrent laboratory tracer estimates (0.03 mmol C m−2 day−1), indicate that ice algal production and its importance within the marine Arctic could be underestimated using traditional approaches. Given careful flux interpretation and with further development, the AEC technique represents a promising new tool for assessing oxygen dynamics and sea-ice productivity in ice-covered regions.
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  • 9
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    Autonomous Robotic Network to Resolve Coastal Oxygen Dynamics : Cruise No. AL547, 20.10. – 31.10.2020, Kiel – Kiel, ARCODYN (2022)
    GEOMAR Helmholtz Centre for Ocean Research Kiel
    Details
    Publication Date: 2022-10-25
    Description: The ALKOR cruise AL547 represents a concluding milestone of the Helmholtz innovation project ARCHES (Autonomous Robotic Networks to Help Modern Societies). The aim was to implement a heterogeneous robotic sensing network to simultaneously monitor changes in the water column and at the seafloor. The network has been developed by a consortium of partners from AWI, DLR, GEOMAR and the University of Kiel. The participating sensing platforms allow for real-time data transfer and the entire network shall be able to autonomously respond to environmental changes in the ocean. The network comprised seven different mobile and stationary platforms. Tests were conducted at the Mittelgrund working area in the entrance of the Eckernförde Bay (western Baltic Sea). During 47 stations the various sensing platforms were deployed and recovered for maintenance. A total of 87853 messages were sent using hydro-acoustics, of which 71734 messages contained O 2 data, 15177 were status messages, 926 messages were commands to trigger a change of the measurement behavior of a platform and 16 messages represented broadcasts about the environmental status. We synoptically recorded short-term O 2 time series on the different platforms, which were placed along a depth gradient in the working area. As the Eckernförde Bay is known for sporadic fish kills by anoxia we hope to contribute to a better understanding of the O 2 dynamics in coastal areas.
    Type: Report , NonPeerReviewed
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  • 10
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    PlasPI marine cameras: Open-source, affordable camera systems for time series marine studies (2020)
    Elsevier
    Details
    Publication Date: 2023-02-08
    Description: Imaging underwater can be particularly problematic and expensive given the harsh environmental conditions posed by salinity and for some deployments, pressure. To counter these difficulties, expensive waterproof pressure resistant housings are often used, commonly built from expensive materials such as titanium, if intended for long duration deployments. Further, environmental investigations often benefit from replicate data collection, which additionally increases study costs. In this paper we present a new camera system, developed with off the shelf and 3D printed cost effective components for use in shallow waters of 〈150 m depth. Integrating Raspberry Pi Zero W microcomputers with open source design files and software, it is hoped these camera systems will be of interest to the global marine and freshwater research communities.
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