Journal of Marine Science and Engineering

Little information on the phytoplankton community in the Yellow Sea (YS)—especially size-fractionated phytoplankton—is currently available, in comparison to the various physicochemical studies in the literature. Using high-performance liquid chromatography (HPLC), size-fractionated phytoplankton communities were seasonally investigated in the YS in 2019. In the study period, diatoms (55.0 ± 10.2%) and cryptophytes (16.9 ± 9.3%) were the dominant groups. Due to the recent alteration in inorganic nutrient conditions reported in the YS, the contribution of diatoms was lower than in previous studies. The large-sized phytoplankton group (>20 µm) was dominated mostly by diatoms (89.0 ± 10.6%), while the small-sized phytoplankton group (<20 µm) was also dominated by diatoms (41.9 ± 9.1%), followed by cryptophytes (19.2 ± 9.8%). The contributions of small-sized diatoms (<20 µm) have been overlooked in the past, as they are difficult to detect, but this study confirms significant amounts of small-sized diatoms, accounting for 62.3% of the total diatoms in the YS. This study provides an important background for assessing the seasonal variations in different-sized diatom groups in the YS. Further detailed studies on their potential ecological roles should be conducted, in order to better understand marine ecosystems under future warming scenarios. Full article

Tidal bores are a natural phenomenon with high flow velocity and destructive potential. A spur dike is a widely used river regulation and embankment protection structure that minimizes erosion, promotes deposition, and protects riverbanks. However, the scouring mechanism around a spur dike under the action of a tidal bore is not fully understood, and accurately estimating the maximum scour depth has always been a challenge, limiting the construction and maintenance of spur dikes in estuarine and marine environments. This study analyzed the scouring characteristics around a spur dike induced by tidal bores via field observation and model experiments. The results show that the scours around a spur dike can be divided into dike head scour and upstream side scour. The scour depth is related to the geometric shape of the spur dike and its surrounding riverbed, hydrodynamic forces, and sediment characteristics. The least squares method obtained the fitting formulas for the depth of the scour at the dike head and upstream side. Overall, the present study indicates an agreement of the scouring characteristics around a spur dike between the field observations and laboratory experiment, and the fitting formulas can be effectively applied to engineering practices of a macro-tidal estuary. Full article

Compared with the traditional mooring system, the automated vacuum mooring system can meet the development needs of large-scale ship automation, port automation, and environmental protection. This review describes the latest research focuses, progress, applications, and future perspectives regarding the automated vacuum mooring system. First, the components, working principles, advantages, limits, and risks of the automated vacuum mooring system are discussed. Secondly, typical application cases of automated vacuum mooring systems are introduced, looking at two aspects of the ship-based system and shore-based system. Then, the routine maintenance of the automated vacuum mooring system is introduced. Finally, a discussion on the challenges and future perspectives of the automated vacuum mooring system is provided in this review. The advantages of an automated vacuum mooring system make it a potentially highly effective and economical option for a wider range of ship mooring than a traditional mooring system. Full article

The present study aims to evaluate the difference in the fluid-dynamic behavior of an overtopping wave energy converter under the incidence of irregular waves based on a realistic sea state when compared to the incidence of regular waves, representative of this sea state. Thus, the sea data of three regions from the Rio Grande do Sul coast, Brazil, were considered. Fluent software was employed for the computational modeling, which is based on the finite volume method (FVM). The numerical generation of waves occurred through the imposition of the velocity boundary conditions using transient discrete values through the WaveMIMO methodology. The volume of fluid (VOF) multiphase model was applied to treat the water–air interaction. The results for the water amount accumulated in the device reservoir showed that the fluid-dynamic behavior of the overtopping converter has significant differences when comparing the two proposed approaches. Differences up to 240% were found for the water mass accumulated in the overtopping device reservoir, showing evidence that the results can be overestimated when the overtopping device is analyzed under the incidence of the representative regular waves. Furthermore, for all studied cases, it was possible to approximate the water volume accumulated over time in the overtopping reservoir through a first-degree polynomial function. Full article

Entrapped air in the chambers of a T-girder bridge generates a considerably large vertical force which is harmful to the safety of the bridge superstructure. The contribution of the entrapped air is not considered when calculating flood force in the related specifications, and also it has not been taken into account by researchers. Two-dimensional, scaled-down models at a 1:40 scale are selected as the research object. Analytical and numerical methods are employed to investigate the contribution of entrapped air in T-girder chambers to flood forces. Results show that the entrapped air in the rear chambers could escape easier than that in the front chambers and the compressibility of entrapped air has a small influence on drag force and vertical force (generated by dynamic pressure) coefficients, but it reduces the buoyancy of the T-girder. Considering the entrapped air compressibility and entrapped air escape, the calculation method of the buoyancy of entrapped air is proposed to improve the precision of the existing flood force calculation method. Full article

Studying mixing and re-stratification during and after hurricanes have important implications for the simulation of circulation and bio-geochemical processes in oceanic and shelf waters. Numerical experiments using FVCOM on an unstructured computational mesh were implemented to study the direct effect of hurricane winds on the mixing and temperature redistribution of the stratified Louisiana shelf during Hurricane Katrina (2005), as well as the post-storm re-stratification timescale. The model was forced by Katrina’s wind stress obtained from a combination of H-Wind database and NCEP model. The climatological profiles of temperature and salinity for August (the month in which Katrina occurred) from the world ocean atlas (WOA, 2013) were used as the pre-storm conditions over the shelf. Model results for sea surface temperature (SST) and mixed layer depth (MLD) were validated versus SST data from an optimally interpolated satellite product, and the MLD was calculated from the heat budget equation of the mixed layer. Model results were used to examine the temporal and spatial responses of SST and MLD over the shelf to Katrina. Results showed that intense mixing occurred within 1–1.1 RMW (RMW is the radius of maximum wind for Katrina), with turbulent mixing as the dominant mixing force for regions far from the eye, although upwelling was an important contributor to modulating SST and MLD. During the peak of Katrina and for the shelf regions severely affected by the hurricane wind, three distinct temperature zones were formed across the water column: an upper mixed layer, a transition zone, and a lower upwelling zone. Shelf re-stratification started from 3 h to more than two weeks after the landfall, depending on the distance from the track. The mixing during Hurricane Katrina affected the seasonal summertime hypoxic zone over the Louisiana shelf and likely contributed to the water column re-oxygenation. Full article

Accurate evaluations of the available and technically exploitable wave energy resources are fundamental to optimise the design and implementation of energy converters in the marine environment. However, long-term resource assessments have been primarily conducted for large-scale devices in offshore energetic locations, thus ignoring onshore sites such as harbours with easier access, installation and accessibility to devices. Here, we conducted a ten-year evaluation of the performance of wave energy converters (WECs) off Roscoff harbour (northern Brittany, France). As the site of application shows moderately energetic conditions, particular attention was dedicated to small-scale WECs by adapting ratings to the local wave climate. This investigation combined (i) a high-spatial resolution (~5 m) hindcast database established with SWAN with (ii) generic and specific assessments of WEC performance. We exploited, in particular, scaled power matrices derived from the Oyster technology to assess the capacity factors and energy output of devices. In addition to characterising the annual and seasonal variability of the available resource off the harbour breakwater, this investigation provided further insights for optimising WECs, including experimental prototypes. It is therefore suggested that this type of evaluation be considered for the assessment of small- and/or full-scale energy converters in the marine environment. Full article

Recreational SCUBA diving is currently a nature-based USD multibillion tourism industry across the globe. However, degradation of many recreational diving destinations all over the world due to “soft” ecotourists necessitates the adoption of innovative management measures. Hellenic Centre for Marine Research (HCMR) developed an innovative technology for the creation of artificial underwater ecotourism attractions (“oases”) to divert visitors away from sensitive marine natural areas of high ecological and aesthetic value. This innovative technology includes specially constructed artificial reefs in an attempt to simulate the functional and morphological characteristics and the aesthetics of the natural rocky reefs. In this study, a pilot survey was conducted in three diving centres of Crete Island, one of the most important tourist destinations in the Mediterranean Sea, involving the participation of 144 SCUBA divers from all over the world. The survey aimed at investigating SCUBA divers’ profiles and perceptions concerning recreational diving activities and artificial reefs technology. Findings of this study indicate that large naval shipwrecks combined with innovative man-fabricated constructions simulating natural rocky reefs meet the preferences of the majority of the participants of the survey and they can be used as an alternative tool for relevant marine ecotourism sustainable applications. Full article

The paper examines the sampling effectiveness of seabin devices and the composition of floating marine litter in port areas. Sampling was carried out from May to September 2021 in Port of Cristo and Port of Colonia de Sant Jordi on Mallorca Island, Spain. This is the first study of the composition of floating marine litter in the ports of Mallorca collected by seabin devices. During the study, 15,899 items and 336 kg of litter were collected and analyzed. The results indicate that seabin effectively collects floating litter from sea surfaces different in size (2 mm to 40 cm). Microplastics (60.8%) were the most commonly found litter, followed by soft plastic items > 5 mm (11.6%) and unidentified hard plastic items > 5 mm (9.6%). Significantly more marine litter was collected in the Port of Cristo (78.6%), compared to the collection of one device in the Port of Colonia de Sant Jordi (21.4%). Time series analysis showed that the average seasonal component was highest in May (68% above baseline). The linear time trend with an R2 of 52.25% indicated the acceptable significance of the model. Full article

The Vendée Globe is the world’s most famous solo, non-stop, unassisted sailing race. The Institute of Marine Sciences and the Barcelona Ocean Sailing Foundation installed a MicroCAT on the One Ocean One Planet boat. The skipper, Dídac Costa, completed the round trip in 97 days, from 8 November 2020 to 13 February 2021, providing one measurement of temperature and conductivity every 30 s during navigation. More than half of the ship’s route was in the sub-Antarctic zone, between the tropical and polar fronts, and it passed through areas of oceanographic interest such as Southern Patagonia (affected by glacier melting), the Brazil–Malvinas confluence, the Southern Pacific Ocean, and the entire Southern Indian Ocean. This sailing race gave a rare opportunity to measure in-situ sea surface salinity in a region where satellite salinity measurements are not reliable. Due to the decreased sensitivity of brightness temperature to salinity in cold seas, retrieving sea surface salinity at high latitudes remains a major challenge. This paper describes how the data are processed and uses the data to validate satellite salinity products in the sub-Antarctic zone. The sailing race measurements represent surface information (60 cm depth) not available from drifters or Argo floats. Acquiring measurements using round-the-world sailing races would allow us to analyse the evolution of ocean salinity and the impact of changes in the ice extent around Antarctica. Full article

The exploitation of thermophilic hydrocarbon-utilizing bacilli could provide novel environmentally friendly surfactants. In this work, 80 thermophilic bacilli isolated from shallow hydrothermal vents of the Eolian Islands (Italy) were screened for their ability to utilize hydrocarbons and produce biosurfactants (BSs). Among them, 15 strains grew with kerosene or gasoline (2% v/v) as the only carbon and energy source, and most of them were positive to the methylene blue agar as prescreening assay for BSs production and displayed emulsifying activity. The cell-free supernatants (CFSs) from two selected strains, Bacillus licheniformis B3-15 and Bacillus horneckiae SBP3, were both surface active and able to emulsify different hydrocarbons and vegetable oils. BSs from B3-15 (910 mg L⁻¹) and SBP3 (950 mg L⁻¹) were chemically different surfactin-like lipopeptides, with specific mineral-, castor- and crude oil removal ability from the cotton matrix. CFSs from the 15 thermophilic strains, which harbor both lipolytic and surfactant abilities, could be suitable for industrial-based applications and environmental issues, such as oil recovery and removal from polluted areas or surfaces, (e.g., oil pipelines, bilge tankers, or industrial silos), whereas the crude BSs, as high-value compounds, may be used in different fields of application, as detergent, cosmeceutical, and pharmaceutical industries. Full article

Gas hydrates (GH) are well known to have an influential effect on the velocity and attenuation of gas hydrate-bearing sediments (GHBS). Based on rock physics modeling, sediment velocity has been extensively used to characterize the distribution of gas hydrate. However, the results obtained from different models show a significant variation. In this study, we firstly review and compare the existing rock physics modeling for velocity and attenuation. The assumption, characteristics, theoretical basis, and workflow of the modeling are briefly introduced. The feasibility and limitations of the published models are then discussed and compared. This study provides insight into how to select a suitable rock physics model and how to conduct modeling in the application of the rock physics model to field data. Then, we introduce how to predict hydrate saturation, hydrate morphology, the dip angle of fracture, sediment permeability, and attenuation mechanisms from the comparison between the modeled and measured acoustic properties. The most important application of rock physics modeling is predicting the hydrate saturation and we discuss the uncertainties of the predicted saturation caused by the errors related to the velocity measurements or rock physics modeling. Finally, we discuss the current challenges in rock physics modeling related to optimizing the input parameters, choice of a suitable model, and upscaling problems from ultrasonic to seismic and well log frequencies. Full article

It is thought that the active physiological regulation of the chemistry of a parent fluid is an important process in the biomineralization of scleractinian corals. Biological regulation of calcification fluid pH (pH_CF) and other carbonate chemistry parameters ([CO₃²⁻]_CF, DIC_CF, and Ω_CF) may be challenged by CO₂ driven acidification and temperature. Here, we examine the combined influence of changing temperature and CO₂ on calcifying fluid regulation in four common Caribbean coral species—Porites astreoides, Pseudodiploria strigosa, Undaria tenuifolia, and Siderastrea siderea. We utilize skeletal boron geochemistry (B/Ca and δ¹¹B) to probe the pH_CF, [CO₃²⁻]_CF, and DIC_CF regulation in these corals, and δ¹³C to track changes in the sources of carbon for calcification. Temperature was found to not influence pH_CF regulation across all pCO₂ treatments in these corals, in contrast to recent studies on Indo-Pacific pocilloporid corals. We find that [DIC]_CF is significantly lower at higher temperatures in all the corals, and that the higher temperature was associated with depletion of host energy reserves, suggesting [DIC]_CF reductions may result from reduced input of respired CO₂ to the DIC pool for calcification. In addition, δ¹³C data suggest that under high temperature and CO₂ conditions, algal symbiont photosynthesis continues to influence the calcification pool and is associated with low [DIC]_CF in P. strigosa and P. astreoides. In P. astreoides this effect is also associated with an increase in chlorophyll a concentration in coral tissues at higher temperatures. These observations collectively support the assertion that physicochemical control over coral calcifying fluid chemistry is coupled to host and symbiont physiological responses to environmental change, and reveals interspecific differences in the extent and nature of this coupling. Full article

Diverse forms of offshore oil and gas structures are utilized for a wide range of purposes and in varying water depths. They are designed for unique environments and water depths around the world. The applications of these offshore structures require different activities for proper equipment selection, design of platform types, and drilling/production methods. This paper will provide a general overview of these operations as well as the platform classifications. In this paper, a comprehensive review is conducted on different offshore petroleum structures. This study examines the fundamentals of all types of offshore structures (fixed and floating), as well as the applications of these concepts for oil exploration and production. The study also presents various design parameters for state-of-the-art offshore platforms and achievements made in the industry. Finally, suitable types of offshore platforms for various water depths are offered for long-term operations. An extension of this study (Part II) covers sustainable design approaches and project management on these structures; this review helps designers in understanding existing offshore structures, and their uniqueness. Hence, the review also serves as a reference data source for designing new offshore platforms and related structures. Full article

The Marine Institute of Ireland operates a network of weather buoys around Ireland. A wave of 32.3 m height (crest–trough) was recorded by one of these buoys, the M6 buoy, off the coast of Ireland in October 2020. In this paper, the technological evolution of this network is explored, with a particular emphasis on this extremely high wave. Raw data and bulk parameters collected during the event are presented, and the wider met-ocean context is outlined. In addition, wave data across the buoy deployment period from dual wave sensors installed on the buoy are analysed. Differences in calculation methods are discussed, rogue incidence rates are calculated, and the sensors are found to be generally in good agreement for key sea state parameters. Considerations specific to this network of buoys are described, including recent advances in technology that may affect continuity of historic records. Wave data from the buoys are found to be robust; the importance of keeping technological changes in mind and using the full raw dataset for analysis purposes are highlighted. Full article

The Mediterranean Sea has been consolidated as the second most important destination region in cruise shipping. This paper investigates the dynamics of the contemporary cruise port network in Southern Europe from the perspective of its centrality. To conduct the research, we applied the technique of social network analysis (SNA) to a set of 20 ports. The set of ports forms a network; therefore, we use the SNA to build this network based on nodes (ports) and to analyze the connections between each other. Several network and node metrics are calculated, such as outgoing and incoming centrality degree, betweenness centrality, and hub index. The goals of this research are (1) to explain the dynamics of the cruise port network for contemporary cruise calls in Southern Europe in terms of the centrality of the ports and the connections between ports, and (2) to obtain a series of graphs with the inter-port relationships of the sample of ports analyzed. Important conclusions are revealed: the cruise traffic registered in a port has an impact on several ports in terms of the number of different ports to which it connects and the intensity of the connection between pairs of ports; the role of betweenness centrality is associated with ports of the same destination region and, in some cases, with ports situated in another destination region; and four ports have been identified as hub ports. The results obtained may help itinerary planners identify alternative ports in the configuration of new itineraries to deal with the challenges associated with the COVID-19 pandemic for cruise shipping. Full article

Blue swimmer crabs (Portunus pelagicus) primarily inhabit the coastal regions of Southeast Asia. This study aimed to examine their population genetic structure, phylogeography, and historical demography by applying partial sequences to the control region in the mitochondrial DNA. The analysis focused on 6 populations comprising 166 individual samples collected from Taiwan (Kezailiao Kaohsiung (KK) and Penghu (PH)), mainland China (Xiamen (XM) and Hong Kong (HK)), Vietnam (Hanoi (VN)), and Singapore (SGP). The estimated nucleotide diversity (π) for all of the samples was 0.062, with values ranging between 0.018 (PH) and 0.045 (HK). Our study collected 116 haplotypes and classified them into lineages A and B. The XM, HK, VN, and SGP populations made up lineage A, and the PH and KK populations comprised lineage B. For each lineage, the results highlighted indications of demographic expansion. Lineage A can be traced back to the second-to-last interglacial period, while lineage B possibly originated in the last glacial period. There were significant differences in the F_ST values among the six populations, except for the pairs HK–XM and PH–KK. In conclusion, the phylogeography and genetic structure of P. pelagicus in Southeast Asia were potentially affected by the Pleistocene glacial cycles and human introduction. These findings further highlight the possible dispersal routes of P. pelagicus throughout Southeast Asia. Full article

Robust nonlinear filtering is an important method for tracking maneuvering targets in non-Gaussian noise environments. Although there are many robust filters for nonlinear systems, few of them have ideal performance for mixed Gaussian noise and non-Gaussian noise (such as scattering noise) in practical applications. Therefore, a novel cubature formula and maximum correntropy criterion (MCC)-based robust cubature Kalman filter is proposed. First, the fully symmetric cubature criterion and high-order divided difference are used to construct a new fifth-degree cubature formula using fewer symmetric cubature points. Then, a new cost function is obtained by combining the weighted least-squares method and the MCC loss criterion to deal with the abnormal values of non-Gaussian noise, which enhances the robustness; and statistical linearization methods are used to calculate the approximate result of the measurement process. Thus, the final fifth-degree divided difference–maximum correntropy cubature Kalman filter (DD-MCCKF) framework is constructed. A typical surface-maneuvering target-tracking simulation example is used to verify the tracking accuracy and robustness of the proposed filter. Experimental results indicate that the proposed filter has a higher tracking accuracy and better numerical stability than other common nonlinear filters in non-Gaussian noise environments with fewer cubature points used. Full article