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We use the GEBCO global bathymetric product alongside other data sets, including magnetic anomaly and vertical gravity gradient, to interpret the seabed geomorphology of approximately 24.7 million km2 of the southwestern Pacific Plate at an effective scale of 1:3,000,000. Manual interpretation was performed to accurately define abyssal plain basins, plateaus, troughs, faults, tectonic and volcanic rises, volcanic chains and other geomorphic units. The resulting description of these units and their geographical disposition, placed in the context of current scientific literature, contributes to our understanding of seabed composition and formational history. Other potential applications of this work include its use as a surrogate for regional habitat-type classification in environmental management, support for seabed minerals exploration, and as a constraint in mineral resource estimation.

Aidoo, R. and Sui, T., 2024. Wave-induced seabed response around slope-type breakwaters: Experimental and numerical study. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 834-838. Charlotte (North Carolina), ISSN 0749-0208. Slope-type breakwaters are an essential coastal structure, providing a versatile and cost-effective solution for wave protection. While offering effective wave protection, slope-type breakwaters induce complex responses within the underlying seabed or around them. This study aimed to investigate the intricate relationship among wave characteristics, breakwater, and the resulting pore pressure and liquefaction potential within the seabed around such structures. Laboratory experiments were conducted to investigate wave-structure-seabed interaction in a physical wave flume for this study. By employing the OlaFlow solvers in OpenFOAM, a numerical model was developed to reproduce the laboratory experiments. The main objective of the study was to validate the numerical model with the laboratory results, which a good agreement was achieved between the results. Two wave characteristics, three degrees of saturation, and three rates of permeability were examined with the numerical model in a 160m wave flume model to investigate their effect and influence on wave-induced pore pressure distribution and liquefaction potential around three slope-angled breakwaters. The results show that the physical properties such as degree of saturation and permeability exhibit similar trends of dynamic response, with higher levels having the most influence on the wave-induced pore pressure and liquefaction potential. Additionally, the effect of the slope angles of the breakwater was such that as the slope angle of the breakwater becomes gentler, the liquefaction potential increases.

Rising demand for minerals and metals, including for use in the technology sector, has led to a resurgence of interest in exploration of mineral resources located on the seabed. Such resources, whether seafloor massive (polymetallic) sulfides around hydrothermal vents, cobalt-rich crusts on the flanks of seamounts or fields of manganese (polymetallic) nodules on the abyssal plains, cannot be considered in isolation of the distinctive, in some cases unique, assemblages of marine species associated with the same habitats and structures. In addition to mineral deposits, there is interest in extracting methane from gas hydrates on continental slopes and rises. Many of the regions identified for future seabed mining are already recognised as vulnerable marine ecosystems. Since its inception in 1982, the International Seabed Authority (ISA), charged with regulating human activities on the deep-sea floor beyond the continental shelf, has issued 27 contracts for mineral exploration, encompassing a combined area of more than 1.4 million km2, and continues to develop rules for commercial mining. At the same time, some seabed mining operations are already taking place within continental shelf areas of nation states, generally at relatively shallow depths, and with others at advanced stages of planning. The first commercial enterprise, expected to target mineral-rich sulfides in deeper waters, at depths between 1,500 and 2,000 metres on the continental shelf of Papua New Guinea, is scheduled to begin early in 2019. In this review, we explore three broad aspects relating to the exploration and exploitation of seabed mineral resources: (1) the current state of development of such activities in areas both within and beyond national jurisdictions, (2) possible environmental impacts both close to and more distant from mining activities and (3) the uncertainties and gaps in scientific knowledge and understanding which render baseline and impact assessments particularly difficult for the deep sea. We also consider whether there are alternative approaches to the management of existing mineral reserves and resources, which may reduce incentives for seabed mining.

While the Biodiversity Beyond National Jurisdiction (BBNJ) Agreement establishes a comprehensive environmental impact assessment (EIA) regime, its application of the EIA provisions to the international seabed area (the Area) presents significant challenges. First, International Seabed Authority (ISA) Member States have differing ratification and signature statuses regarding the BBNJ Agreement, leading to fragmented and asymmetrical obligations. Second, normative ambiguity surrounds the “not undermine” proviso, and an institutional disconnection exists between the Clearing-House Mechanism under the BBNJ Agreement and the ISA. Third, the “equivalence exception” under Article 29(4) of the BBNJ Agreement generates a critical interpretive dilemma. The absence of institutional mechanisms for determining equivalence risks unilateral self-assessment and forum-shopping. Furthermore, substantive disparities exist between the BBNJ Agreement and ISA regulations, particularly regarding the screening process, Cumulative Environmental Effects, and Strategic Environmental Assessment, alongside asymmetries in procedural transparency and stakeholder engagement. Finally, an empirical analysis reveals that the EIA practices in the Area remain scarce and inaccessible, and existing Environmental Impact Statements appear not fully aligned with the standards prescribed by Article 33(2) of the BBNJ Agreement. Therefore, this article puts forward recommendations to optimize the application of the EIA provisions under the BBNJ Agreement. First, concerted efforts must be made to advance the ratification and accession of the BBNJ Agreement by ISA Member States. Second, the “not undermine” proviso should be interpreted narrowly to ensure the BBNJ Agreement’s implementation does not actively dismantle the effectiveness of the ISA. Third, Parties should facilitate the determination of equivalence through harmonization and scientific advice, leveraging the supplementary role of the Scientific and Technical Body. Fourth, cooperation must be formalized through institutional frameworks, specifically by signing a Memorandum of Understanding and enhancing inter-institutional expert consultation. Finally, stakeholders must enhance EIA practices by standardizing the mechanism for updating reports and ensuring that dual-member States comply with the standards of both regimes.

The latest negotiating text from the International Seabed Authority (ISA) on the Environmental Compensation Fund (ECF) system shows significant progress compared to the provisions in the 2019 Draft Exploitation Regulations. First, the formulation of the ECF rules and procedures has been further elaborated. Second, the scope of application of the ECF has been more precisely delineated. Third, the mechanisms for funding the ECF have been improved. Fourth, the “polluter-pays principle” has been introduced for the first time. Fifth, a periodic review mechanism has also been incorporated for the first time. Nevertheless, the 2025 Draft continues to exhibit certain deficiencies. First, the financial foundations of the ECF remain unreliable. Several new or modified sources of funding, such as voluntary contributions from member States, targeted contributions from sponsoring States, and donations from international or non-governmental organizations, are inherently uncertain. Second, the text fails to establish clear and operational criteria for determining eligibility to submit claims to the ECF. Third, the scope of compensation available under the ECF remains inadequately defined. Fourth, transparency for stakeholders with respect to the operation of the ECF is insufficient. This study proposes the following recommendations to deal with the abovementioned deficiencies. First, the principles, mechanisms, and specific measures for the ECF fundraising and management should be optimized. Second, with respect to eligible claimants, a multi-tiered and sequential framework is recommended. Third, the scope of the ECF’s compensatory mandate should be refined, and detailed standards developed to ensure that the ECF is used exclusively to address liability gaps where environmental harm cannot otherwise be remedied. Fourth, stakeholder transparency must be enhanced.

The upper part of the Krka River estuary and Prokljan Lake are a specific example of a well-stratified estuarine environment in a submerged river canyon. Here, we reconstructed the geomorphological evolution of the area and classified the data gathered in the study, integrating multibeam echosounder data, backscatter echosounder data, side-scan sonar morpho-bathymetric surveys, and acoustic sub-bottom profiling, with the addition of ground-truthing and sediment analyses. This led to the successful classification of the bottom sediments using the object-based image analysis method. Additional inputs to the multibeam echosounder data improved the segmentation of the seafloor classification, geology, and morphology of the surveyed area. This study uncovered and precisely defined distinct geomorphological features, specifically submerged tufa barriers and carbonate mounds active during the Holocene warm periods, analogous to recent tufa barriers that still exist and grow in the upstream part of the Krka River. Fine-grained sediments, classified as estuarine sediments, hold more organic carbon than coarse-grained sediments sampled on barriers. A good correlation of organic carbon with silt sediments allowed the construction of a prediction map for marine sedimentary carbon in this estuarine/lake environment using multibeam echosounder data. Our findings highlight the importance of additional inputs to multibeam echosounder data to achieve the most accurate results.

This paper deals with the wave-induced cyclic response of a poro-elastic seabed (by means of oscillations of the pore-fluid pressure, soil displacement, effective normal stress and shear stress in a soil skeleton) due to a surface sinusoidal water-wave propagating over a seabed of finite thickness. The main existing analytical solutions to the governing problem, assuming a dual-elastic system of the two-phase (pore-fluid and soil skeleton) seabed medium, are critically discussed, pointing out their limitations, doubtful items, and meaningful errors. The amplitude phenomena is particularly studied as an immanent part of any complex-valued analytical solution of a cyclic nature. A series of calculation analyses, performed for the North Sea wave and soil conditions, has indicated problematic results as far as high values of the shear modulus of soil are concerned. An application of meaningfully different values of the degree of saturation, obtained for one and the same calculation example, has caused many additional doubts as to the quality of the tested analytical solutions.

Despite many of years of mapping effort, only a small fraction of the world ocean’s seafloor has been sampled for depth, greatly limiting our ability to explore and understand critical ocean and seafloor processes. Recognizing this poor state of our knowledge of ocean depths and the critical role such knowledge plays in understanding and maintaining our planet, GEBCO and the Nippon Foundation have joined forces to establish the Nippon Foundation GEBCO Seabed 2030 Project, an international effort with the objective of facilitating the complete mapping of the world ocean by 2030. The Seabed 2030 Project will establish globally distributed regional data assembly and coordination centers (RDACCs) that will identify existing data from their assigned regions that are not currently in publicly available databases and seek to make these data available. They will develop protocols for data collection (including resolution goals) and common software and other tools to assemble and attribute appropriate metadata as they assimilate regional grids using standardized techniques. A Global Data Assembly and Coordination Center (GDACC) will integrate the regional grids into a global grid and distribute to users world-wide. The GDACC will also act as the central focal point for the coordination of common data standards and processing tools as well as the outreach coordinator for Seabed 2030 efforts. The GDACC and RDACCs will collaborate with existing data centers and bathymetric compilation efforts. Finally, the Nippon Foundation GEBCO Seabed 2030 Project will encourage and help coordinate and track new survey efforts and facilitate the development of new and innovative technologies that can increase the efficiency of seafloor mapping and thus make the ambitious goals of Seabed 2030 more likely to be achieved.

As land-based mining industries face increasing complexities, e.g., diminishing return on investments, environmental degradation, and geopolitical tensions, governments are searching for alternatives. Following decades of anticipation, technological innovation, and exploration, deep seabed mining (DSM) in the oceans has, according to the mining industry and other proponents, moved closer to implementation. The DSM industry is currently waiting for international regulations that will guide future exploitation. This paper aims to provide an overview of the current status of DSM and structure ongoing key discussions and tensions prevalent in scientific literature. A narrative review method is applied, and the analysis inductively structures four narratives in the results section: (1) a green economy in a blue world, (2) the sharing of DSM profits, (3) the depths of the unknown, and (4) let the minerals be. The paper concludes that some narratives are conflicting, but the policy path that currently dominates has a preponderance towards Narrative 1—encouraging industrial mining in the near future based on current knowledge—and does not reflect current wider discussions in the literature. The paper suggests that the regulatory process and discussions should be opened up and more perspectives, such as if DSM is morally appropriate (Narrative 4), should be taken into consideration.

Bottom trawlers land around 19 million tons of fish and invertebrates annually, almost one-quarter of wild marine landings. The extent of bottom trawling footprint (seabed area trawled at least once in a specified region and time period) is often contested but poorly described. We quantify footprints using high-resolution satellite vessel monitoring system (VMS) and logbook data on 24 continental shelves and slopes to 1,000-m depth over at least 2 years. Trawling footprint varied markedly among regions: from < 10% of seabed area in Australian and New Zealand waters, the Aleutian Islands, East Bering Sea, South Chile, and Gulf of Alaska to > 50% in some European seas. Overall, 14% of the 7.8 million-km2 study area was trawled, and 86% was not trawled. Trawling activity was aggregated; the most intensively trawled areas accounting for 90% of activity comprised 77% of footprint on average. Regional swept area ratio (SAR; ratio of total swept area trawled annually to total area of region, a metric of trawling intensity) and footprint area were related, providing an approach to estimate regional trawling footprints when highresolution spatial data are unavailable. If SAR was =0.1, as in 8 of 24 regions, therewas > 95% probability that > 90%of seabed was not trawled. If SAR was 7.9, equal to the highest SAR recorded, there was > 95% probability that >70% of seabed was trawled. Footprints were smaller and SAR was =0.25 in regions where fishing rates consistently met international sustainability benchmarks for fish stocks, implying collateral environmental benefits from sustainable fishing. © 2018 National Academy of Sciences. All rights reserved.