Sea Depth Research Articles

Faktor-Faktor Yang Mempengaruhi Hasil Tangkapan Ikan Kembung (Rastrelliger SPP) di Perairan Selat Makassar

This study aims to determine the factors that affect the catch of mackerel in the potential zone of fishing grounds in the Makassar Strait, namely; oceanography sea surface temperature, salinity, current velocity, depth and sea surface chlorophyll content on the catch of mackerel in the potential zone of fishing grounds in the Makassar Strait. The research method used is the survey method, which directly follows the fishing operation. The number of observations was 38 times. Data were analyzed with histogram graphs and also analyzed with multiple linear regression. The results of this study showed that mackerel were generally caught in waters with temperatures between280Cand290C; salinities of 30 ppt and 31 ppt; water depths of about 50 m and 60 m; current speeds of about 0.09 m/s and 0.12 m/s; and chlorophyll-a content of about 1.80 mg/m3 and 2.20 mg/m3. This study has explained that chlorophyll-a content is the dominant factor in relation to mackerel catch.

METHODS FOR SATELLITE DERIVED BATHYMETRY FROM SENTINEL-2 IMAGES: A COMPARISON

Abstract. In recent decades, research has been developed to estimate near-shore bathymetry depth values using satellite imagery. Visible and infrared bands are used to derive elevation profile estimates, so to obtain bathymetric in rapid way without mobilisation of persons or equipment and saving the costs. For consequence, Satellite Derived Bathymetry (SDB) is seen as a valid approach for shallow waters survey: strongly supported by the activity of scholars and researchers, multiple methods are available in the literature. This article aims to investigate and compare different SDB methods for sea depth extraction from Sentinel-2 satellite multispectral images, with particular attention to the accuracy of the results. The experiments are conducted on imagery including Blue, Green, Red and Near Infrared bands, with 10 m resolution, concerning the Bay of Pozzuoli (Italy). After removing the glint, the effects caused by the reflection of sunlight through single scattering from sea surface, three methods are applied: Band Ratio method (BRM), 3rd-degree polynomial regression line method (3DPM), and principal component analysis method (PCAM). 3DPM can be seen as a variant of the BRM where the linear law that interprets the correlation between the band ratio values and the depth values is replaced by the third order function. Models are trained using depth data extracted from an Electronic Navigational Chart (ENC) at 1:7,500 scale, which is also used to verify result accuracy. The experiments demonstrate that the 3DPM is better able to obtain a more precise bathymetric model, confirming the greater adaptability of the 3rd order function to interpretate the variability of the interaction of light with water along the water column.

Deep sea treasures - Insights from museum archives shed light on coral microbial diversity within deepest ocean ecosystems

Deep sea benthic habitats are low productivity ecosystems that host an abundance of organisms within the Cnidaria phylum. The technical limitations and the high cost of deep sea surveys have made exploring deep sea environments and the biology of the organisms that inhabit them challenging. In spite of the widespread recognition of Cnidaria's environmental importance in these ecosystems, the microbial assemblage and its role in coral functioning have only been studied for a few deep water corals. Here, we explored the microbial diversity of deep sea corals by recovering nucleic acids from museum archive specimens. Firstly, we amplified and sequenced the V1–V3 regions of the 16S rRNA gene of these specimens, then we utilized the generated sequences to shed light on the microbial diversity associated with seven families of corals collected from depth in the Coral Sea (depth range 1309 to 2959 m) and Southern Ocean (depth range 1401 to 2071 m) benthic habitats. Surprisingly, Cyanobacteria sequences were consistently associated with six out of seven coral families from both sampling locations, suggesting that these bacteria are potentially ubiquitous members of the microbiome within these cold and deep sea water corals. Additionally, we show that Cnidaria might benefit from symbiotic associations with a range of chemosynthetic bacteria including nitrite, carbon monoxide and sulfur oxidizers. Consistent with previous studies, we show that sequences associated with the bacterial phyla Proteobacteria, Verrucomicrobia, Planctomycetes and Acidobacteriota dominated the microbial community of corals in the deep sea. We also explored genomes of the bacterial genus Mycoplasma, which we identified as associated with specimens of three deep sea coral families, finding evidence that these bacteria may aid the host immune system. Importantly our results show that museum specimens retain components of host microbiome that can provide new insights into the diversity of deep sea coral microbiomes (and potentially other organisms), as well as the diversity of microbes writ large in deep sea ecosystems.

Increased signal of fishing pressure on community life‐history traits at larger spatial scales

AbstractAimHuman pressure in the oceans is pervasive and affects marine life. Understanding species' differing responses to human pressure, and how human pressure compares to other environmental variables in shaping marine communities is needed to facilitate the sustainable management of the seas. Despite theory and empirical evidence that fishing pressure affects marine life‐history strategies, several recent large‐scale studies have not shown strong relationships between fishing pressure and community composition. We aim to reconcile theory with data and explain these variable findings, testing the hypothesis that the signal of the effect of fishing pressure on marine communities depends on the scale at which the community is defined.LocationNorth East Atlantic.Time Period2009 to 2021.Major Taxa StudiedMarine vertebrates (Teleostei, Elasmobranchii, Petromyzonti, Holocephali).MethodsWe collate extensive scientific marine biodiversity surveys, published life‐history traits and high‐resolution annual fishing pressure data. Using frequentist Generalized Linear Mixed Models, we assess whether community mean weighted life‐history traits correlate with fishing pressure, sea surface temperature and depth and whether the strength of these relationships are scale dependant.ResultsWe show fish community life‐history strategy correlates with fishing pressure, and the relative importance of fishing pressure compared to environmental variables increases with the scale at which a community is defined.Main ConclusionsWe suggest this scale dependence relates to the spatial extent over which covariates vary, and how fish movement moderates communities' experience of this variability. Our findings highlight the importance of explicit consideration of scale in ecological research, supporting the idea that studying systems at ecologically relevant scales is necessary to detect and appropriately interpret the effects of global change.

Modeling carbon dioxide removal via sinking of particulate organic carbon from macroalgae cultivation

Macroalgae cultivation is receiving growing attention as a potential carbon dioxide removal (CDR) strategy. Macroalgae biomass harvesting and/or intentional sinking have been the main focus of research efforts. A significant amount of biomass is naturally lost through erosion and breakage of cultivated or naturally growing seaweed, but the contribution of the resulting particulates to carbon sequestration is relatively unexplored. Here, we use a fully coupled kelp-biogeochemistry model forced by idealized parameters in a closed system to estimate the potential of macroalgal-derived particulate organic carbon (POC) sinking as a CDR pathway. Our model indicates that at a kelp density of 1.1 fronds m−3, macroalgal POC sinking can export 7.4 times more carbon to the deep sea (depths > 500m) and remove 5.2 times more carbon from the atmosphere (equivalent to an additional 336.0 gC m−2 yr−1) compared to the natural biological pump without kelp in our idealized closed system. The results suggest that CDR associated with POC sinking should be explored as a possible benefit of seaweed farming and point to the need for further study on organic carbon partitioning and its bioavailability to quantify the effectiveness and impacts of macroalgal cultivation as a CDR strategy.

Enhancing Chub Mackerel Catch Per Unit Effort (CPUE) Standardization through High-Resolution Analysis of Korean Large Purse Seine Catch and Effort Using AIS Data

Accurate determination of fishing effort from Automatic Identification System (AIS) data improves catch per unit effort (CPUE) estimation and precise spatial management. By combining AIS data with catch information, a weighted distribution method is applied to allocate catches across various fishing trajectories, accounting for temporal dynamics. A Generalized Linear Model (GLM) and Generalized Additive Model (GAM) were used to examine the influence of spatial–temporal and environmental variables (year, month, Sea Surface Temperature (SST), Sea Surface Salinity (SSS), current velocity, depth, longitude, and latitude) and assess the quality of model fit for these effects on chub mackerel CPUE. Month, SST, and year exhibited the strongest relationship with CPUE in the GLM model, while the GAM model emphasizes the importance of month and year. CPUE peaked within specific temperature and salinity ranges and increased with longitude and specific latitudinal bands. Month emerged as the most influential variable, explaining 38% of the CPUE variance, emphasizing the impact of regulatory measures on fishery performance. The GAM model performed better, explaining 69.9% of the nominal CPUE variance. The time series of nominal and standardized indices indicated strong seasonal cycles, and the application of fine-scale fishing effort improved nominal and standardized CPUE estimates and model performance.

Hydrodynamic Load Effect on Composite Polymer Cold-Water Pipe Joint in Ocean Thermal Energy Conversion

The cold-water pipe in Ocean Thermal Energy Conversion (OTEC) is a very important part of the process of producing electrical energy. The cold-water pipe functions to convey cold water with a temperature of 5°C from a sea depth of >500 m to the sea surface. The cold water in the pipe is allowed to experience a temperature increase of <3°C so that it can be used to dilute the ammonia in the condenser. The use of polymer composites as cold-water pipe materials is a challenge because the hydrodynamic load from seawater currents fluctuates in a direction perpendicular to the position of the pipe. The pipe length reaches >500 m consisting of several pipes connected using the Friction Stir Welding method. This research was conducted to determine the effect of the hydrodynamic load of seawater currents on Friction Stir Welding (FSW) connections, the stress distribution in pipe joints, and the thickness of pipes that are safe to use as OTEC cold water pipes. In addition, simulations were carried out using Inventor software on pipes with a length of 500 m, a diameter of 4 m, and variations in thickness from 18 cm to 30 cm which produced von Mises yield stress and stress distribution at different joints at each pipe thickness. In pipes with a thickness of less than 20 cm, the stress and stress distribution are purely influenced by the hydrodynamic load of seawater currents. Meanwhile, in pipes with a thickness greater than 24 cm, the stress that occurs in the pipe is influenced by the current and weight of the pipe. In pipes with a thickness greater than 24 cm, the stress in the pipe is concentrated in the middle of the joint which is the critical part of the pipe and is the initial point of failure. It was found that at a pipe thickness of 22 cm, the stress was distributed almost evenly because the stress caused by seawater currents was reduced by the heavy load of the pipe. So, from the simulation of cold-water pipes with polymer composite materials that experience hydrodynamic loads from seawater currents varying in thickness from 16 cm to 30 cm, it is recommended to use a pipe thickness of 22 cm so that the pipe connection is safer as an ocean-based OTEC cold water pipe application.

Predicting bathymetry based on vertical gravity gradient anomaly and analyses for various influential factors

The prediction of bathymetry has advanced significantly with the development of satellite altimetry. However, the majority of its data originate from marine gravity anomaly. In this study, based on the expression of vertical gravity gradient (VGG) of a rectangular prism, the governing equations for determining sea depths to invert bathymetry. The governing equation is solved by linearization through an iterative process, and numerical simulations verify its algorithm and its stability. We also study the processing methods of different interference errors. The regularization method improves the stability of the inversion process for errors. A piecewise bilinear interpolation function roughly replaces the low-frequency error, and numerical simulations show that the accuracy can be improved by 41.2 % after this treatment. For variable ocean crust density, simulation simulations verify that the root-mean-square (RMS) error of prediction is approximately 5 m for the sea depth of 6 km if density is chosen as the average one. Finally, two test regions in the South China Sea are predicted and compared with ship soundings data, RMS errors of predictions are 71.1 m and 91.4 m, respectively.

Average Displacement of Multi-Beam Measurement Vessel based on 2D Particle Swarm Algorithm

To address the optimization of a survey vessel's navigation route, this study uses historical sea depth data from a maritime area several years ago as an example. The research employs the two-dimensional Particle Swarm Optimization (2DPSO) algorithm to calculate the direction and distance for vessel navigation while adhering to constraints, aiming to obtain the optimal route for the survey vessel. Traditional Particle Swarm Optimization exhibits rapid early-stage convergence, but slows in the later stages and is susceptible to local optima. Hence, we opt for the 2DPSO algorithm, known for its simpler structure and incorporation of penalty functions to constrain particle values. This enhances algorithm performance and minimizes the risk of falling into local optima, offering a better solution to optimal route planning.

Two efficient numerical techniques for solutions of fractional shallow water equation

In this paper, the nonlinear shallow water equation appears in the mathematical modeling of tsunami wave propagation along the coastline of an ocean is solved numerically. The model investigates fractional derivatives and is presented through a system of nonlinear partial differential equations. The variational iteration method (VIM) and the residual power series method (RPSM) have been applied to the fractional system of equations for different parameters. In addition, tsunami wave velocity and run-up height with respect to coast slope and sea depth are analyzed for different time and order in detail. A detailed error analysis is presented for tsunami velocity and tsunami wave propagation. The results obtained are compared to other existing results to show the efficiency and reliability of the proposed methods.

Environmental Variability of the Northern Caspian Sea during Khazarian Epoch (Based on Drilling Data)

The objective of our work was to reconstruct transgressive-regressive events in the Northern Caspian Sea during the Khazarian epoch of its Pleistocene history to determine the natural conditions of the development of the basins and to assess their response to climate change. This work is based onstudies of the sedimentary formations of the upper part of the Quaternary sequence in the Northern Caspian Sea. The borehole was drilled in the eastern part of the depression Shirotnaya, the sea depth was 11.9 m, and the depth of drilling was 56.4 m. The core was subjected to lithological, malacological, and palynological analysis. This paper discusses the results related to the interval 56.0–26.6 m. The structure, facies-lithological, and malacological composition of the core capture three transgressive stages of the Caspian, namely the Early Khazarian, Late Khazarian, and Hyrcanian stages, separated by regressive phases. The representative spore-pollen assemblages made it possible to carry out the climatic and stratigraphic subdivision of the studied Khazarian deposits and to suggest a provisional version of the history of climatic and phytocenotic events during the sedimentation period. The results of our studies have introduced new discussion points into the paleogeography of the Northern Caspian Sea.

Quantification of the Wave Energy Potential of the Atlantic Coast of Honduras

The growing demand for electricity in Honduras became a critical problem in 2022, evidencing an increase of 3.05%. This situation generated difficulties in the energy supply, and an increase of 10% to 15% in the cost of electricity was projected for the next quarter of 2023. Despite the efforts in renewable energies, the wave energy potential generated by the Atlantic waves is limited due to the lack of research in Honduras. To obtain a wave energy potential, meteorological data was collected on the swell, including wave height and wave interval, taking into account other factors such as density and sea depth. For this process, A variety of available resources were used, such as web scraping programming made in Python, and the data were obtained using the online software Windfinder. These were stored in Microsoft Excel, and mathematical models such as wave energy power and wave power formula were used, which considered parameters such as wave height and wave intervals. In addition, Airy’s theory equation was applied, taking into account the depth; these models allowed calculating the wave energy potential and comparing the results. Preliminary results indicate that the wave energy generation potential varies according to the model used, with the first model, wave energy power, varying 51%, the second, wave power formula, 46%, and Airy’s theory equation. This research was done to quantify the wave energy potential in the country of Honduras, specific to the Atlantic coast on the coasts of the departments of Cortés, Atlántida, Colón, Gracias a Dios, and Islas de la Bahía over a period of 10 weeks and contribute to future research.

Geometric analysis of pontoon and mooring line towards hydrodynamic response

Floating Photovoltaics (FPV) are renewable energy producing technological breaktroughs whic are suitable to circumtances of lakes across Indonesia. The core of this technology is the function of working transformers installed on the pontoons. An FPV with 145 Mwac capacity is designed to run on Cirata weir by utilizing pontoons with the length of 16.5 meters. The hydrodynamic response in the form of plane and rotation movements due to surrounding loads (including but not limited to wave, wind and sea depth data) calculated by using Response Amplitude Operator (RAO) concept. The wave period measured in meter from 0 to 180 ° incoming degree, the biggest translational response comes from pontoon i.e 0.986 (m/m) in sway direction, spread mooring is used to limit the pontoon’s movement. Using weighing concept, in operating condition Tension Mooring Line is obtained at the value of 1.67 for pontoon. While in extreme condition the obtained value is 2.5.

Distribution Analysis of Green Mussels (Perna viridis) in Banyuurip Village, Ujung Pangkah District, Gresik Regency

The aim of the research was to determine the Distribution analysis of Perna viridis diversity based on the suitability map for green mussel cultivation, analysis of community perceptions and the condition of water bodies. Perna viridis aquaculture is suitable for the waters of Banyuurip village based on the variables of sea depth, sea surface temperature, chlorophyll a concentration, and substrate radiance data. Heavy metal content of Pb is located and distributed in polluted areas. It was found that the potential for green mussel aquaculture is greater in warm water habitats, i.e. closer to the coast. In addition, the northeast was identified as a suitable habitat for green mussels. The mid-ocean area in the north-west is of low suitability due to the lack of substrate and chlorophyll. Analysis of community attitudes and behaviour showed that people remain enthusiastic about green mussel farming, although green mussel shell waste remains an environmental problem. Heavy metal analysis of green mussel samples showed that green mussels are still safe for consumption. Therefore, the main conclusion is that the habitat of Perna viridis in the waters of Banyuurip Village still has potential for cultivation, but the waters must be free from pollution.

Modelling the upwelling radiance detected in a seawater column for oil-in-water emulsion tracking

This study concerns changes in the solar light transfer in seawater as a result of the appearance of oil substances in the form of oil-in-water emulsions. The expected effect of the studies is to gather knowledge that would be useful in designing an optical sensor for monitoring oil substances penetrating the seawater column. The paper presents the process of the Monte Carlo modelling of the upwelling radiance detected by a virtual underwater sensor. Moreover, this article discusses the predicted difference between the intensity of the signal from the upwelling radiance meter and the signal from the downwelling radiance meter. The modelling results suggest that in order to obtain a strong signal indicating the presence of oil substances, the radiance meter should receive light running upwards in the sea depth.

Optimization design and experiment study on a water hydraulic flexible actuator integrating flexible inner skeleton and soft external skin used for underwater flexible gripper

A water hydraulic flexible gripper with three flexible actuators is proposed, which integrates a soft external skin and a flexible inner skeleton to enhance resistance against water pressure. To investigate the deformation characteristics of the water hydraulic flexible actuator, a mathematical model is established to describe the relationship between water pressure and actuator deformation. The effects of different materials, structural sizes, and inlet pressure are analyzed through simulation. A Kriging model is utilized to fit the simulation results, while a multi-island genetic algorithm is employed to obtain an optimal solution for the structure of the flexible actuator. Finally, the deformation of the flexible actuator under various inlet pressures is quantified through experimental measurements, and the obtained results exhibit degree of consistency with the simulation outcomes. After completing static experiments at a simulated sea depth of 1000 m, the tip forces of flexible actuators were tested, and then land and underwater grasping experiments were conducted. The water-hydraulic flexible actuator developed in this study has great potential for handling fragile or deformable objects during deep-sea. This promotes the application of water-hydraulic flexible manipulators in the field of underwater robotics, providing higher flexibility and adaptability compared to traditional rigid manipulators.

Analysis of kinematic characteristics of a mobile caterpillar robot with a SCARA-type manipulator

Automation and robotization of various production and technological processes in many industries is one of the leading trends in the development of modern society. Industrial robots have recently become quite widespread, and it is almost impossible to imagine any modern production in the fields of mechanical engineering (machine building), instrumentation, pharmaceuticals, food, chemical industries, etc., without robotic complexes. Over the past few decades, another area of robotics has emerged: autonomous mobile robots. It combines research in mechanics, electronics, and computer technologies, including artificial intelligence. Among the most common applications of autonomous mobile robots are the performance of various technological operations in places that are dangerous to human life (radiation, biological or chemical contamination) or uninhabitable (space, sea depths, volcanic craters, etc.). Mobile robots have also proven themselves in rescue operations during cataclysms and natural disasters, anti-terrorist operations, military operations, mine clearance, etc. Given the urgency of the issue of mobile robotics development, this article proposes a new design of an autonomous robotic complex built on the basis of a tracked chassis and equipped with a SCARA-type manipulator. The main task of the developed robot is to perform various technological operations in places where human presence is dangerous or impossible, in particular, when performing demining tasks. In the course of the research, the kinematics of the manipulator was analyzed in detail to determine its working area, and the kinematic parameters of the tracked chassis were experimentally tested while it was moving over rough terrain. The obtained results can be used to further improve the design and control system of the robot and manipulator and in the process of determining the specific technological tasks that will be assigned to this robotic platform.

Межэкотопические различия в видовом составе растительных сообществ с низким и высоким участием доминирующих видов

Межэкотопические различия в видовом составе растительных сообществ с низким и высоким участием доминирующих видов

KONTRIBUSI FAKTOR FISIKA KELAUTAN TERHADAP PEMBUDIDAYAAN RUMPUT LAUT (EUCHEUMA COTTONII) DI DESA RIA BAO KECAMATAN NAGAWUTUNG KABUPATEN LEMBATA

Research Objectives To determine the contribution of marine physics factors to the cultivation of seaweed (Eucheuma cottonii) in Ria Bao Village, Nagawutung District, Lembata Regency.This type of research uses quantitative research. The population in this study is the coastal area of ​​Ria Bao Village, Nagawutung District, Lembata Regency. The sample in the study was taken from the entire population, namely there are three points for determining the location of seaweed cultivation in the coastal area of Ria Bao Village, Nagawutung District, Lembata Regency. The three points were chosen intentionally (purposive sampling). It is planned to measure marine physical factors with a distance of 0.5 to 1 km from the shoreline to the sea, or a depth limit that is still possible for the development of seaweed cultivation.Data sources consist of primary data and secondary data. Data collection techniques are observation, and documentation. The analysis technique is using matrix of land suitability for seaweed cultivation. Research Results (1) The Contribution of Marine Physics Factors to Seaweed Cultivation is the Current Speed Factor (point 1=0.18m/s, point 2=0.30m/s, point 3=0.21m/s), Sea Depth (point 1=3.81 m, point 2=1.93 m, point 3=3.57 m), Brightness (point 1=2.80 m, point 2=1.20 m, point 3=1.60 m) , Temperature (point 1=290C, point 2=300C, point 3=300C), and tides (0.30 m) .

A novel design of a hybrid glulam-steel substructure for the IEA 15-MW floating wind turbine

Wind energy has become increasingly recognised as a very promising type of renewable energy. In addition, floating offshore wind turbines have facilitated the development of electricity production in intermediate (45-150 m) and deep sea (>150 m) depths. Despite this, wind turbine manufacturing, installation, and operation may generate substantial greenhouse gas emissions. A novel hybrid glulam-steel floating substructure design is presented in this research, intended for the IEA 15 MW floating wind turbine. The objective is to contribute to advancing floating wind energy while minimising costs and carbon dioxide emissions. The objective of the novel design is to substitute steel with glued laminated lumber (glulam). It showcases an altered iteration of the UMaine VolturnUS-S semi-submersible platform originally created for the IEA 15 MW turbine. Before selecting one of three preliminary hybrid wood-steel models, the Ansys Workbench 2020 R1 is used to evaluate and appraise them per a set of criteria extracted from pertinent timber and steel standards. The chosen hybrid design conserves about 590 metric tonnes of steel mass compared to the UMaine VolturnUS-S semi-submersible platform. The selected model is then validated by executing a fully coupled aero-hydro-servo-elastic dynamic analysis with OpenFAST. Consideration is limited to the ultimate limit state design (ULS) for normal and severe operating situations. The utilisation factor of the glulam supporting structure for the IEA 15 MW turbine ranges from 74% to 94%, indicating that it is an effective load-bearing solution.