Climate Mitigation through Biological Conservation: Extensive and Valuable Blue Carbon Natural Capital in Tristan da Cunha’s Giant Marine Protected Zone

Carbon-rich habitats can provide powerful climate mitigation if meaningful protection is put in place. We attempted to quantify this around the Tristan da Cunha archipelago Marine Protected Area. Its shallows (<1000 m depth) are varied and productive. The 5.4 km2 of kelp stores ~60 tonnes of carbon (tC) and may export ~240 tC into surrounding depths. In deep-waters we analysed seabed data collected from three research cruises, including seabed mapping, camera imagery, seabed oceanography and benthic samples from mini-Agassiz trawl. Rich biological assemblages on seamounts significantly differed to the islands and carbon storage had complex drivers. We estimate ~2.3 million tC are stored in benthic biodiversity of waters <1000 m, which includes >0.22 million tC that can be sequestered (the proportion of the carbon captured that is expected to become buried in sediment or locked away in skeletal tissue for at least 100 years). Much of this carbon is captured by cold-water coral reefs as a mixture of inorganic (largely calcium carbonate) and organic compounds. As part of its 2020 Marine Protection Strategy, these deep-water reef systems are now protected by a full bottom-trawling ban throughout Tristan da Cunha and representative no take areas on its seamounts. This small United Kingdom Overseas Territory’s reef systems represent approximately 0.8 Mt CO2 equivalent sequestered carbon; valued at >£24 Million GBP (at the UN shadow price of carbon). Annual productivity of this protected standing stock generates an estimated £3 million worth of sequestered carbon a year, making it an unrecognized and potentially major component of the economy of small island nations like Tristan da Cunha. Conservation of near intact habitats are expected to provide strong climate and biodiversity returns, which are exemplified by this MPA.

A Novel Method on Hydrographic Survey Technology Selection Based on the Decision Tree Supervised Learning

Hydrographic survey or seabed mapping plays an important role in achieving better maritime safety, especially in coastal waters. Due to advances in survey technologies, it becomes important to choose well-suited technology for a specific area. Moreover, various technologies have various ranges of equipment and manufacturers, as well as characteristics. Therefore, in this paper, a novel method of a hydrographic survey, i.e., identifying the appropriate technology, has been developed. The method is based on a reduced elimination matrix, decision tree supervised learning, and multicriteria decision methods. The available technologies were: remotely operated underwater vehicle (ROV), unmanned aerial vehicle (UAV), light detection and ranging (LIDAR), autonomous underwater vehicle (AUV), satellite-derived bathymetry (SDB), and multibeam echosounder (MBES), and they are applied as a case study of Kaštela Bay. Results show, considering the specifics of the survey area, that UAV is the best-suited technology to be used for a hydrographic survey. However, some other technologies, such as SDB come close and can be considered an alternative for hydrographic surveys.

Seafloor Methane Seepage Related to Salt Diapirism in the Northwestern Part of the German North Sea

This study focuses on seafloor methane seep sites and their distribution in the northwestern part of the German North Sea. Methane seepage is a common phenomenon along marine shelves and known to occur in the North Sea, but proof of their existence was lacking in the study area. Using a ship-based multibeam echosounder we detected a minimum of 166 flares that are indicative for free gas releases from the seafloor in the German “Entenschnabel” area, which are not related to morphologic expressions at the seafloor. However, a group of small depressions was detected lacking water column anomalies but with indications of dissolved fluid release. Spatial analysis revealed that flares were not randomly distributed but show a relation to locations of subsurface salt diapirs. More than 60% of all flares were found in the vicinity of the salt diapir “Berta”. Dissolved methane concentrations of ∼100 nM in bottom waters were ten times the background value in the “Entenschnabel” area (CH4 &lt; 10 nM), supporting the finding of enhanced seepage activity in this part of our study area. Furthermore, locations of flares were often related to acoustic blanking and high amplitude reflections in sediment profiler echograms, most prominently observed at location Berta. These hydroacoustic signatures are interpreted to result from increased free gas concentrations in the sediments. Electromagnetic seabed mapping depicts local sediment conductivity anomalies below a flare cluster at Berta, which can be explained by small amounts of free gas in the sediment. In our area of interest, ten abandoned well sites were included in our mapping campaign, but flare observations were spatially not related to these wells. Naturally seeping methane is presumably transported to the seafloor along sub-vertical faults, which have formed concurrently to the updoming salt. Due to the shallow water depths of 30 to 50 m in the study area, flares were observed to reach close to the sea surface and a slight oversaturation of surface waters with methane in the flare-rich northeastern part of the working area indicates that part of the released methane through seepage may contribute to the atmospheric inventory.

High resolution mapping of the Arctic Ocean deepest area: Molloy Hole

&lt;p&gt;New hydro-oceanographic data were collected in the Arctic Ocean during HIGN NORTH20 marine geophysical campaign performed in July 2020, in a COVID-19 pandemic period. HIGH NORTH20 was developed as part of the IT-Navy HIGH NORTH program, a Pluriannual Joint Research Program in the Arctic devoted to contribute to oceans knowledge in order to ensure ocean science improving conditions for sustainable development of the Ocean in the aim of United Nations Decade of Ocean Science for Sustainable development and the GEBCO - SEABED 2030 project. In order to contribute in exploration and high-resolution seabed mapping new data was collected using a multibeam echosounder (EM 302 - 30 kHz). The particular sea ice environmental condition with open-sea allowed to survey and mapping the Molloy Hole, the deepest sector of the Arctic Ocean, a key area in the global geodynamics and oceanographic context. A 3D model of the Molloy Hole (804 km&lt;sup&gt;2&lt;/sup&gt;) and the detection of the deepest seafloor (5567m - 79&amp;#176; 08.9&amp;#8217; N 002&amp;#176; 47.0&amp;#8217; E) was obtained with a 10x10m grid in compliance to the IHO standards.&lt;/p&gt;

Development of a Seabed Geomorphology classification approach; aspiring towards a robust tool to support comprehensive and consistent seabed mapping

&lt;p&gt;In 2016, through a collaboration between marine mapping programmes in Norway, Ireland, and the UK, we published a new classification scheme to aid the characterisation of seabed geomorphology (Dove et al., 2016). The classification scheme was developed to address shared objectives and challenges in seabed mapping, particularly to enable more consistent classification where required. The novel aspect of this framework was the effort to independently describe seabed features according to their observed physical 1-Morphology, and the more subjective interpretation of their origin and evolution (2-Geomorphology). Initial application of the approach within our own groups and externally proved promising, and through the welcome involvement of colleagues from Geoscience Australia, we continued to progress and improve the approach.&lt;/p&gt;&lt;p&gt;We are now within the second phase of the project, which involves the development of glossaries for both parts of the classification scheme. The glossary for part-1 Morphology was recently completed and published (Dove et al., 2020). This glossary includes a revised list of feature names, with definitions and representative diagrams for each feature. Feature definitions are in-part drawn from the International Hydrographic Organization (IHO) guide for undersea feature names, which were modified and augmented with additional terms to ensure the final feature catalogue and glossary encompasses the diversity of morphologies observed at the seabed.&lt;/p&gt;&lt;p&gt;Part-2 Geomorphology glossary is now in development. We anticipate it to be more complicated than the Morphology glossary due to the (often) variable meaning of different terms between different fields and individual scientists. But as for Part 1, our primary objective is to produce a useful and robust framework (applicable from the coastal zone to the abyss), that minimises duplication and/or ambiguity as much as possible. The Geomorphology glossary will include example bathymetry images to add further value.&lt;/p&gt;&lt;p&gt;Dove, D., Bradwell, T., Carter, G., Cotterill, C., Gafeira Goncalves, J., Green, S., Krabbendam, M., Mellett, C., Stevenson, A., Stewart, H. and Westhead, K., Scott, G., Guinan, J., Judge, M., Monteys, X., Elvenes, S., Maeten, N., Dolan, M., Thorsnes, T., Bjarnadottir, L., Ottesen, D., 2016. Seabed geomorphology: a two-part classification system. British Geological Survey, Open Report OR/16/001.&lt;/p&gt;&lt;p&gt;Dove, D., Nanson, R., Bjarnad&amp;#243;ttir, L.R., Guinan, J., Gafeira, J., Post, A., Dolan, M.F.J., Stewart, H., Arosio, R. and Scott, G., 2020. A two-part seabed geomorphology classification scheme:(v. 2). Part 1: morphology features glossary.&lt;/p&gt;

Feasibility of Objective Seabed Mapping Techniques in a Coastal Tidal Environment (Wadden Sea, Germany)

The growing interest in monitoring the marine environment has strongly encouraged governmental agencies and research institutes to undertake seabed mapping programs and stimulated scientific interest in innovative mapping methods and tools. In this study, object-based image analysis was used to map a very shallow tidal inlet, characterized by high sediment variability and intense morphodynamic processes. The aim was to test the feasibility of reproducible mapping approaches within extended mapping programs of complex coastal areas. The study is based on full-coverage, high-resolution bathymetry and reflectivity, calibrated by means of sediment samples. Seafloor segmentation and classification were based on a cluster analysis performed on reflectivity, slope, and ruggedness. Statistics of clusters were extracted and analysed to identify the optimal number of clusters and evaluate the suitability of the clustering process to differentiate different seabed types. Clusters and samples data were joined to create a training and validation dataset for characterizing the seabed and carrying out an accuracy assessment. Misclassifications were explored and referred to three main reasons: (i) The not-perfect correspondence between sediment boundaries of classification systems and boundaries derived from the clustering process; (ii) the geomorphological features of the seabed; and (iii) the position accuracy of samples. The study contributes to testing of the feasibility of objective methods and highlights the importance of joining acoustic, lithological, and geomorphological analysis. It highlights issues and the need to critically analyse the mapping results and improve the accuracy of collected data.

Systemic risk of cruise ship incidents from an Arctic and insurance perspective

Easier accessibility and demand for so-called last chance tourism has contributed to rapid growth in Arctic cruise ship tourism. Arctic cruising brings many benefits to remote coastal communities but also presents an array of risks. In the light of this context, this article explores the concept of systemic risk of cruise ship incidents in general, findings which are then placed in an Arctic context and consideration given of the role the insurance sector may play in addressing cruise ship incidents. The study is based on metadata, both from academic and nonacademic sources. Findings are drawn from 11 global case studies of cruise ship incidents, 5 of which are polar examples. In the worst-case scenario, an array of serious economic, business, environmental, sociocultural, and security impacts may unfold in the Arctic, presenting risks that may be considerably worse than in other parts of the world. Arctic-specific challenges include extreme weather conditions and the presence of sea-ice, navigation and communication conditions, and lack of infrastructure (port facilities, Search and Rescue capabilities). Significant knowledge gaps across the Arctic have been identified, for example, in terms of seabed mapping, how to deal with industry-related activities, and the risks and nature of environmental change. When cruise ship risks in the Arctic are considered, both passenger and shipowner risk need to be accounted for, including Search and Rescue cover. Although data are limited, there is evidence that the sociocultural risks of an Arctic cruise ship incident are insufficiently addressed, either via insurance mechanisms or cross-border, navigational safety guidelines such as the Polar Code. The academic contribution of the study is the systemic scale of the analysis, and the practical and political implications are to lay the foundation for solution discussion that is of relevance in an Arctic and insurance context.

Seabed Mapping: A Brief History from Meaningful Words

Over the last few centuries, mapping the ocean seabed has been a major challenge for marine geoscientists. Knowledge of seabed bathymetry and morphology has significantly impacted our understanding of our planet dynamics. The history and scientific trends of seabed mapping can be assessed by data mining prior studies. Here, we have mined the scientific literature using the keyword “seabed mapping” to investigate and provide the evolution of mapping methods and emphasize the main trends and challenges over the last 90 years. An increase in related scientific production was observed in the beginning of the 1970s, together with an increased interest in new mapping technologies. The last two decades have revealed major shift in ocean mapping. Besides the range of applications for seabed mapping, terms like habitat mapping and concepts of seabed classification and backscatter began to appear. This follows the trend of investments in research, science, and technology but is mainly related to national and international demands regarding defining that country’s exclusive economic zone, the interest in marine mineral and renewable energy resources, the need for spatial planning, and the scientific challenge of understanding climate variability. The future of seabed mapping brings high expectations, considering that this is one of the main research and development themes for the United Nations Decade of the Oceans. We may expect a new higher resolution ocean seafloor map that might be as influential as The Floor of the Oceans map.