Exploitation Of Deep-sea Resources Research Articles

A High-Precision Inverse Finite Element Method for Shape Sensing and Structural Health Monitoring

In the contemporary era, the further exploitation of deep-sea resources has led to a significant expansion of the role of ships in numerous domains, such as in oil and gas extraction. However, the harsh marine environments to which ships are frequently subjected can result in structural failures. In order to ensure the safety of the crew and the ship, and to reduce the costs associated with such failures, it is imperative to utilise a structural health monitoring (SHM) system to monitor the ship in real time. Displacement reconstruction is one of the main objectives of SHM, and the inverse finite element method (iFEM) is a powerful SHM method for the full-field displacement reconstruction of plate and shell structures. However, existing inverse shell elements applied to curved shell structures with irregular geometry or large curvature may result in element distortion. This paper proposes a high-precision iFEM for curved shell structures that does not alter the displacement mode of the element or increase the mesh and node quantities. In reality, it just modifies the methods of calculation. This method is based on the establishment of a local coordinate system on the Gaussian integration point and the subsequent alteration of the stiffness integration. The results of numerical examples demonstrate that the high-precision iFEM is capable of effectively reducing the displacement difference resulting from inverse finite element method reconstruction. Furthermore, it performs well in practical engineering applications.

Legal Implications of Deep Seabed Mining on the Sustainability of the Blue Economy in Indonesia

This research examines the legal implications of deep seabed mining on blue economy sustainability. Indonesia, as an archipelagic country, has enormous marine potential that needs to be managed with a blue economy approach to support sustainable economic growth and community welfare. This research uses a normative legal method with a statutory approach to analyze various related regulations. The results show that deep seabed mining can make a significant contribution to the economy, especially through the extraction of minerals such as nickel, copper and cobalt. However, this activity also poses serious environmental risks, including damage to marine ecosystems and increased carbon emissions that impact climate change. Therefore, a comprehensive and sustainable regulatory framework is needed, integrating blue economy and precautionary principles to ensure that the exploitation of deep-sea resources is carried out responsibly and sustainably.

Improvement for modeling the damping of the wake oscillator based on the Van der Pol scheme

Given the importance of risers and umbilical cables in the exploitation of deep-sea resources, the vortex induced vibration (VIV) of long flexible cylinders has been systematically studied, and it is acknowledged that the wake oscillator is a satisfactory tool in practically predicting the VIV for offshore engineering applications. Based on the conventional wake oscillator with different damping term formulations, the present study systematically explores the influences of the coefficients and the maximum order of a polynomial damping term within the Van der Pol type wake oscillator. More specifically, the coefficients of the second-order polynomial are adjusted to vary inside a reasonable range, and the polynomial order is increased from the conventional specification of 2–4, 6, and 8. The vibrations of the flexible cylinder predicted by the revised wake oscillator are compared to the measurements taken from an experiment reported in the literature. The comparison indicates that increasing polynomial coefficients generally reduce VIV dominant mode numbers. In addition, increasing the polynomial order aligns the dominant mode more closely with experimental data, although this effect diminishes when the polynomial order exceeds 4. It is argued that the gradual change in phase differences along the cylinder induced by increasing either polynomial coefficient or maximum order could be the reason. The present study sheds light into the mechanism for the damping effect observed in hydrodynamic forces observed in VIVs and lays the foundation for suggesting an optimal formulation of the damping terms as 0.45q2+0.6q−0.3 compared to the conventional formulation of 0.3q2−0.3.

Distribution, vertical migration, and trophic ecology of lanternfishes (Myctophidae) in the Southwestern Tropical Atlantic

Lanternfishes (Myctophidae) are among the most abundant, widespread, and diverse fish groups in the world ocean. They account for a significant part of oceanic fish biomass and play crucial roles in various ecosystem processes, including carbon sequestration and nutrient recycling. However, despite the increasing risks they face (e.g. global warming, plastic pollution, and exploitation of deep-sea resources), many aspects of the lanternfishes ecology still remain poorly known. Here, we investigate the species composition, vertical migration, and trophic ecology of lanternfishes in the Southwestern Tropical Atlantic (SWTA) and the influence of physicochemical factors on their horizontal structuring. We show that lanternfishes are a highly diverse and an abundant fish family of the SWTA, comprising at least 33 species and contributing 40% of all fish collected (in number). We reveal that some of these species may differ in their patterns of prey composition and migratory behaviour, leading to multidimensional niches, underestimated trophic links (e.g. gelatinous organisms), and several mechanisms to avoid competitive exclusion. At least 73% of the lanternfish species reported here seem to migrate to the surface to feed at night. Additionally, they are a central food source for mesopelagic and bathypelagic predators, thereby connecting shallow and deep-sea ecosystems. Finally, we show that the structure of lanternfish assemblages is not strongly affected by environmental conditions analysed here (i.e., throughout the thermohaline structure and current systems), leading to weak horizontal assemblage separation.

Expert Assessment of Risks Posed by Climate Change and Anthropogenic Activities to Ecosystem Services in the Deep North Atlantic

Sustainable development of the ocean is a central policy objective in Europe through the Blue Growth Strategy and globally through parties to the Convention on Biological Diversity. Achieving sustainable exploitation of deep sea resources is challenged by the huge uncertainty around the many risks posed by human activities on these remote ecosystems and the goods and services they provide.We used a Delphi approach, an iterative expert-based survey process, to assess risks to ecosystem services in the North Atlantic Ocean from climate change (water temperature and ocean acidification), the blue economy (fishing, pollution, oil and gas activities, deep seabed mining, maritime and coastal tourism and blue biotechnology), and their cumulative effects. Ecosystem services from the deep sea identified through the Millennium Ecosystem Assessment framework were presented in an expert survey to assess the impacts of human drivers on these services. The results from this initial survey were analyzed and then presented in a second survey. The final results based on 55 expert responses indicated that pollution and temperature change each pose high risk to more than 28% of deep-sea ecosystem services whilst ocean acidification, and fisheries both pose high risk to more than 19% of the deep-sea ecosystem services. Services considered to be most at risk of being impacted by anthropogenic activities were biodiversity and habitat as supporting services, biodiversity as a cultural service, and fish and shellfish as provisioning services. Tourism and blue biotechnology were not seen to cause serious risk to any of the ecosystem services. The negative impacts from temperature change, ocean acidification, fishing, pollution, and oil and gas activities were deemed to be largely more probable than their positive impacts. These results expand our knowledge of how a broad set of deep-sea ecosystem services are impacted by human activities. Furthermore, the study provides input in relation to future priorities regarding research in the Atlantic deep sea.

Exploitation of deep-sea resources: The urgent need to understand the role of high pressure in the toxicity of chemical pollutants to deep-sea organisms

The advent of industrial activities in the deep sea will inevitably expose deep-sea organisms to potentially toxic compounds. Although international regulations require environmental risk assessment prior to exploitation activities, toxicity tests remain focused on shallow-water model species. Moreover, current tests overlook potential synergies that may arise from the interaction of chemicals with natural stressors, such as the high pressures prevailing in the deep sea. As pressure affects chemical reactions and the physiology of marine organisms, it will certainly affect the toxicity of pollutants arising from the exploitation of deep-sea resources. We emphasize the need for environmental risk assessments based on information generated from ecotoxicological trials that mimic, as close as possible, the deep-sea environment, with emphasis to a key environmental factor – high hydrostatic pressure.

Inter-annual dynamics of abyssal polychaete communities in the North East Pacific and North East Atlantic—A family-level study

Characterising how deep-sea communities change on contemporary time-scales and understanding underlying ecosystem processes has become important under changing climate and the rise in the exploitation of deep-sea resources. However, little is known about these dynamics and processes. Long-term observations from which inter-annual variations can be detected are scarce in the deep sea. This study examines inter-annual changes in density, family richness and evenness, family and functional group rank abundance distributions of infaunal polychaetes at two abyssal stations in the North East Pacific (Station M, 1991 to 2005) and in the North East Atlantic (Porcupine Abyssal Plain, 1991 to 1999). The two long-term data sets were used to investigate not only if polychaete community structure and composition varied at inter-annual scales in terms of diversity and rank abundance distributions but also if any changes were related to previous observations in megafauna and environmental factors at each locality. The polychaete community structure at each locality was analysed using univariate statistics as well as multivariate ordination techniques based on Bray-Curtis similarity of the yearly family density. Sub-surface deposit feeders, such as Paraonidae, dominated the North East Pacific, whereas surface deposit feeders, such as Cirratulidae, dominated the North East Atlantic. Both stations showed inter-annual variations in density, family evenness and rank abundance distributions. The greatest changes occurred in 1998 in both time series when polychaete densities peaked, and switches in the rank abundance of the most abundant families and functional groups took place. Inter-annual variations in the polychaete community were correlated with a limited number of holothurian species changes, but no correlation was found with particulate organic matter flux or climate indices. Ecological and environmental factors behind the family-level changes remain elusive. Overall, changes in the dominance of functional groups imply changes in abyssal ecosystem functioning with potential consequences on carbon cycling at the seabed.

Basing conservation policies for the deep-sea floor on current-diversity concepts: a consideration of rarity

Exploitation of deep-sea resources is now underway and there is economic pressure to renew and expand currently restricted waste disposal in that environment. Since the deep sea is noted for very high species diversity, it is appropriate that diversity conservation be initiated. Review of current concepts of diversity maintenance finds that the ideas have evolved more through increasing information about sources of heterogeneity than through rigorous testing. This history weakens the immediate value of these concepts for the development of conservation strategies and demonstrates the need for additional investigation. Such inquiry might focus upon the rare component of overall species richness. A comparison of box core samples at 2100m in the western Atlantic and the Gulf of Mexico continental shelf reveals that deep soft bottoms are not unique in having many rare species. The rare component at depth is largely comprised of species more common at other locations near and far. The rare component on the shelf is comprised mostly of species which are consistently rare and restricted in distribution. These observations suggest a shallow–deep difference that is more one of degree than fundamental in nature; the deep having larger regions and regional species pools.

Ressourcen der Tiefsee: “Erbschaft” und Verantwortung der Menschheit

The exploitation of deep-sea mineral resources was first proposed almost three decades ago. Several ore types have been discovered and some have been investigated for their commercial exploitation. From the outset, the need for environmental risk assessments has been realized and a number of specific studies have been conducted to determine the likely severeness of impacts from commercial mining. Two factors, the generally infavourable level of world metal prices and the formulation of Part XI of the Law of the Sea (signed in 1982), have both militated against future developments of deep-sea mining and its associated technology. The more important results of earlier environmental impact studies point to the fact that, in order to properly assess the consequences of large-scale ocean disturbances, investigations must be conducted on large areal and long-time scales. Currently, this new approach is applied in studies on faunal recolonization following large-scale, experimental disturbances of the deep-sea floor. However, many other predicted impacts from deep-sea mining need to be investigated before such mining may commence after the coming decades. Most important in future studies will be the careful monitoring of an industrial endurance test (Pilot Mining Operation) of several months. The high level of funding and of oceanographic expertise required to sustain such an extended research project demand international collaboration and cost sharing. The concept of the deep-sea as “common heritage of mankind”, – and this specifically in respect to the exploitation of deep-sea resources – as it had been proposed by Arvid Pardo in 1967 and adopted by the United Nations in 1970 in view of the developing countries' interest, should be extended by the statement that the health of the ocean is the “responsibility of mankind”.

The argument for an interim arrangement

The application of an international interim regime for the ocean floor prior to the entry into force of a Law of the Sea Convention would enable timely exploitation of deep sea resources and would help towards the settlement of divergent opinions. The telecommunications organizations Intelsat and Inmarsat provide examples of how this may be successfully achieved.