The regionalization process promoted by the EU's Common Fisheries Policy (CFP) enabled the formulation of a new governance arrangement at the sub-national regional level of the Northern Adriatic Sea (NAS). Given the potential for dominating narratives to foster simplified solutions for fishery management, the article sought to analyze discourse formations across Italian Regional Fishery Departments (RFDs) of the NAS. A discourse analysis based on the Discursive Agency Approach (DAA) delineated the discursive strategies, while a weak vs strong sustainability narrative was adopted to broadly group stakeholders into discourse coalitions. The results showed the presence of a dominating narrative in RFD settings, prioritizing the economic growth of the fishery sector - particularly the trawling industry - over current environmental concerns. The study points to a possibly increasing dominance of weak sustainability narratives in the Italian NAS and invites for stakeholders' representation to significantly broaden and diversify, enabling the development of multifaceted solutions to the NAS crisis.
Crude oil and cadmium (Cd) are common pollutants in Ghana's coastal ecosystems, where the cyanobacterial phytoplankton Synechococcus sp. serves as the primary producer and forms the base of the marine food web alongside small grazers. We hypothesized that cadmium and crude oil would disrupt microbial community structure and function, with the strongest effects under combined exposure. This study investigates the toxic effects of Oil (2 mL L−1), Cd (4.4 μg L−1), and their combined impact (Cd + Oil) on functional groups within the coastal microbial community, including Synechococcus sp., heterotrophic bacteria, nanoflagellates, eukaryotic phytoplankton, ciliates, and dinoflagellates, as well as on copepod nauplii and copepodite development during six-day incubations. We observed acute toxic effects on heterotrophic ciliates and dinoflagellates, with >50 % reductions in abundance within 6 h and a marked decrease in diversity. Phytoplankton showed growth within the first 24 h due to nutrient replenishment from the protist decay, however, their growth continued to decline after 24 h, with Synechococcus being particularly sensitive to Cd and less affected by Oil. In contrast, heterotrophic bacteria increased in abundance across all treatments, likely benefiting from organic matter released during phytoplankton decay and their high adaptability. Notably, the bacterial genera Marivivens and Rhodovulum became dominant mainly in the Oil-amended treatments. Overall, the microbial groups exhibited diverse responses to the pollutants, with the combined Cd + Oil treatment exerting the strongest negative effects, while crude oil alone had the least impact. These findings highlight the vulnerability of tropical microbial food webs, typically dominated by Synechococcus and microbial grazers, to combined pollutant stress, with potential cascading effects on higher trophic levels and coastal ecosystem productivity. This highlights the need for comprehensive monitoring and conservation efforts in these globally significant, yet understudied, regions.
Ship designers face increasing pressure to comply with global emission reduction ambitions. Alternative fuels, potentially derived from bio-feedstock or renewable electricity, provide promising solutions to this problem. The main challenge is to identify a suitable ship power system, given not only uncertain emission requirements but also uncertain fuel and carbon emission prices. We develop a two-stage stochastic optimization model that explicitly considers uncertain fuel and carbon emission prices, as well as potential retrofits along the lifetime. The bi-objective setup of the model shows how the choice of optimal power system changes with reduced emission levels. Methanol and LNG configurations appear to be relatively robust initial choices due to their ability to run on fuel derived from different feedstocks, and their better retrofittability towards ammonia or hydrogen. From a policy perspective, our model provides insight into the effect of the different types of carbon pricing mechanisms on a shipowner's decisions.
In this study, the periodic train timetabling problem is formulated using a time-space graph formulation that exploits the properties of a symmetric timetable. Three solution methods are proposed and compared where solutions are built by what we define as a dive-and-cut-and-price procedure. An LP relaxed version of the problem with a subset of constraints is solved using column generation where each column corresponds to the train paths of a line. Violated constraints are added by separation and a heuristic process is applied to help to find integer solutions. The passenger travel time is computed based on a solution timetable and Benders’ optimality cuts are generated allowing the method to integrate the routing of the passengers. We propose two large neighborhood search methods where the solution is iteratively destroyed and repaired into a new one and one random iterative method. The problem is tested on the morning rush hour period of the Regional and InterCity train network of Zealand, Denmark. The solution approaches show robust performance in a variety of scenarios, being able to find good quality solutions in terms of travel time and path length relatively fast. The inclusion of the proposed Benders’ cuts provide stronger relaxations to the problem. In addition, the graph formulation covers different real-life constraints and has the potential to easily be extended to accommodate more constraints.
We consider a variant of the berth allocation problem-i.e., the multi-port berth allocation problem-aimed at assigning berthing times and positions to vessels in container terminals. This variant involves optimizing vessel travel speeds between multiple ports, thereby exploiting the potentials of a collaboration between carriers (shipping lines) and terminal operators. Using a graph representation of the problem, we reformulate an existing mixed-integer problem into a generalized set partitioning problem, in which each variable refers to a sequence of feasible berths in the ports that the vessel visits. By integrating column generation and cut separation in a branch-and-cut-and-price procedure, our proposed method is able to outperform commercial solvers in a set of benchmark instances and adapt better to larger instances. In addition, we apply cooperative game theory methods to efficiently distribute the savings resulting from a potential collaboration and show that both carriers and terminal operators would benefit from collaborating.
In this paper, we study a problem that integrates the vessel scheduling problem with the berth allocation into a collaborative problem denoted as the multi-port continuous berth allocation problem (MCBAP). This problem optimizes the berth allocation of a set of ships simultaneously in multiple ports while also considering the sailing speed of ships between ports. Due to the highly combinatorial character of the problem, exact methods struggle to scale to large-size instances, which points to exploring heuristic methods. We present a mixed-integer problem formulation for the MCBAP and introduce an adaptive large neighborhood search (ALNS) algorithm enhanced with a local search procedure to solve it. The computational results highlight the method's suitability for larger instances by providing high-quality solutions in short computational times. Practical insights indicate that the carriers’ and terminal operators’ operational costs are impacted in different ways by fuel prices, external ships at port, and the modeling of a continuous quay.
In this paper, full-scale data for two ships have been used for the comparison of five different added resistance methods. The effect of using separate wave spectra for wind waves and swell on performance prediction has been explored. The importance of the peak enhancement factor(γ) in the JONSWAP spectrum for added resistance computation has been studied. Simulation model including calm water resistance, added resistance and wind resistance has been used. Ships have been simulated in the same weather conditions and propeller speed as in the case of full-scale ships using different methods for added resistance. The performance of these methods has been quantified by comparing speed and power predictions with the full-scale data. The paper also discusses the challenges involved in using full-scale data for such a comparison because of difficulty in isolating the effect of added resistance in full-scale data. It was observed that three out of five methods were able to predict added resistance even in high waveheights. Even though these methods showed significantly different RAOs, its effect on speed and power prediction was minor. Simulation results were not sensitive to the choice of peak enhancement factor(γ) in the JONSWAP spectrum. There was minor improvement in results by using separate wave spectra for wind waves and swell instead of single wave spectrum for combined wind waves and swell.
A conceptual design framework for collision and grounding analysis is proposed to evaluate the crashworthiness of double-hull structures. This work attempts to simplify the input parameters needed for the analysis, which can be considered as a step towards a design-oriented procedure against collision and grounding. Four typical collision and grounding scenarios are considered: (1) side structure struck by a bulbous bow, (2) side structure struck by a straight bow, (3) bottom raking, (4) bottom stranding. The analyses of these scenarios are based on statistical data of striking ship dimensions, velocities, collision angles and locations, as well as seabed shapes and sizes, grounding depth and location. The evaluation of the damage extent considers the 50- and 90-percentile values from the statistics of collision and grounding accidents. The external dynamics and internal mechanics are combined to analyse systematically the ship structural damage and energy absorption under accidental loadings.
The power to regulate on-board protection of merchant vessels lies with the flag state. However, the national models of regulation are not developed in a unilateral vacuum. In fact, the whole concept of flag state jurisdiction and legislative power has to be understood and exercised on the national level in close relation with the general regime of the international law of the sea. The aim of the article is therefore two-fold: first, it aims to provide a background for the country reports in this special issue by giving a brief insight into the problem of piracy in the twenty-first century and the international approaches towards this problem. Here the article also provides an insight into the legal background by presenting the concept of piracy in the law of the sea and connected law enforcement powers. Thus, this part of the article provides the overall context in which the discussions concerning on-board protection and the development of national regulations have occurred. Second, the article analyses the issue of on-board protection from the perspective of the legal framework in international law, as well as relevant international soft-law instruments, influencing the development on the national level. On-board protection of vessels as such is not regulated in the international law; however, international law provides a form of general legal setting, in which flags states navigate. Thus, this article aims to draw a picture of the international context in which flags states develop their specific legal approach.
The core function of UNCLOS is to provide a legal order for the oceans and their peaceful uses. This includes providing a legal framework for upholding law and order at sea, as this is a precondition for peaceful use. Part One of this volume deals with different perspectives of upholding law and order at sea; and Chapter 2 creates a backdrop for the following chapters dealing with these various issues. The chapter presents some perspectives on the system of law and order at sea and sets the following chapters in context with themes such as the scope of UNCLOS and its limitations, the adaptability of the convention to new developments, the role of the zonal system created under the convention and the influence of state practice on the system of upholding law and order at sea. By doing so, Chapter 2 also creates a line to the following parts of this volume; and some of the perspectives raised in Chapter 2 will be revisited in the final part (Part Four) of this volume, dealing with UNCLOS as a system of regulation and connected methodologies.