Hydrodynamic Performance of Open-frame Deep Sea Remotely Operated Vehicles Based on Computational Fluid Dynamics Method

The resistance performance and motion stability of deep sea remotely operated vehicles (ROVs) subjected to underwater motion conditions are studied on the basis of the unsteady Reynolds-averaged Navier-Stokes method combined with the six-degree-of-freedom equation of motion to quickly and accurately predict them. In the modeling process, we consider the complexity of ROV geometry and thus reduce the model to a series of regular geometries to maximize the position and weight of the original components. The grid and value slots of an ROV are divided, and the surface is reconstructed. The forward, backward, transverse, floating, and submerged resistance of ROVs are simulated and compared with existing experimental forces to determine the accuracy of the calculation method. Then, the oblique navigation of the ROV on the horizontal and vertical planes is studied. Furthermore, the motion response of the ROV to direct horizontal motion, heave, pitch, and yaw are studied. The force, moment, and motion time curves are obtained. The stability of ROV motion is analyzed to provide technical support for the safety of ROVs.

Roles of Geospatial Technologies in Hydrographic Practice

Any seafarer or mariner that uses the sea knows that navigation without correct charts is impossible and hazardous because nautical charts are the most essential and indispensable tools for vessels to sail safely at sea. For vessels to safely sail at sea, the seas and the oceans ought to be charted and this falls within the domain of hydrography. However, the seas cannot be charted effectively in the absence of the deployment of human resources and adequate tools like satellite and aerial imagery, survey boats and other equipment that will facilitate the hydrographic operations. The acquisition of data and information about the sea depths, nature of sea bed, waterways, navigational hazards and navigational objects among others, basically falls within the sphere of hydrography which is primarily known as survey at sea. The paper offers a review of geospatial technologies in hydrographic practice for enhanced safety of navigation at sea. The review is important to both the mariners, shipping industry and the government in order to explore the potentials provided by Geographic Information System, Remote Sensing, cloud GIS, big data GIS and Global Positioning System to enhance the practice of hydrography. The data and materials used for the review were obtained from literature in the internet and other published works. The paper looked at hydrography as a profession, roles of geospatial technologies in hydrographic practice, benefits of hydrography to national development and finally, the weaknesses of geospatial technologies in hydrographic practice were equally examined.

Analysis of Shoreline Changes in Ikoli River in Niger Delta Region Yenagoa, Bayelsa State Using Digital Shoreline Analysis System (DSAS)

The use of Digital Shoreline Analysis System was used to determine shoreline changes in Ikoli River, Yenagoa, Bayelsa State. Shoreline data were extracted from satellite imagery over thirty years (1991-2021). The basis of this study is to use Digital Shoreline Analysis System to determine erosion and accretion areas. The result reveals that the average erosion rate in the study area is 1.16 m/year and the accretion rate is 1.62 m/year along the Ikoli River in Ogbogoro Community in Yenagoa, Bayelsa State. The mean shoreline length is 5.24 km with a baseline length of 5.2 km and the area is classified into four zones to delineate properly area of erosion and accretion based on the five class of Linear regression rate, endpoint rate and weighted linear rate of which zone I contain very high erosion and high erosion with an area of landmass 255449.93 m2 of 38%, zone II contain moderate accretion, very high accretion and high accretion with a land area of 1666816.46 m2 with 24%, zone III has very high erosion and high erosion with an area of landmass 241610.85 m2 of 34 % and zone IV contain moderate accretion and high accretion with land area 30888.08 m2 with 4%. Out of the four zones, zone I and II were found to be eroding with 72% and zone II and IV contain accretion with 28%. The result shows that 44% of the area have been eroded. Therefore, coastal engineers, planners, and shoreline zone management authorities can use DSAS to create more appropriate management plans and regulations for coastal zones and other coastal parts of the state with similar geographic features.

Site Fidelity and Residency of Tursiops truncatus off the Aragua Coast, Venezuela-First Records of Long Residency

This study represents the first comprehensive analysis of the residency patterns of a coastal population of bottlenose dolphin off the coast of Aragua, Venezuela, over a multi-year period. Using photo-identification, the most recent study (2019-2020) identified 56 individuals with the time between encounters from one to 344 days between the first and last sighting. Site Fidelity (SF) and Residence (RES) indices were calculated and Agglomerative Hierarchical Clustering (AHC) modeling was performed, with three patterns of residence obtained: resident (25%), semiresident (17.86%) and transient (57.14%). These results were contrasted with remodeled data from a previous study (2006-2007), showing similar patterns: resident (24.44%), semi-resident (28.89%) and transient (46.67%). Importantly, two individuals were found to have been resident over the extended period. A breeding female sighted for the first time in 2004 and again in 2020 (16 years) and the other from 2005 to 2020 (15 years). This region is an important area for marine mammals, known to support a resident reproductive population over many years, as well seabirds, sea turtles, whale sharks and fishermen. We recommend that consideration be given to designating the waters as a Marine Protected Area to safeguard the existing population and provide benefit to the surrounding marine environment.

Mass Beach Stranding of Blue Button Jellyfishes, Porpita porpita (Linnaeus 1758) from the Coast of Mandvi, Kutch, India during August, 2021

Present short communication reports about beach stranding of Porpita porpita (Linnaeus 1758) from the Coast of Mandvi, Kutch during August 2021. Also, this is the first record of the blue button jellyfishes for the northern Gulf of Kutch region. A study was carried out by primary observation and measurements of common environmental parameters such as Sea Surface Temperature (SST), Wind Direction & Wind Speed. Aboral and oral parts were observed and described. It is assumed that the large biomass of blue button jellyfish on the beach is due to strong shoreward Monsoon winds.

Spatial Analysis of Maritime Piracy in the Gulf of Guinea

Humans rely on the sea for food and mineral resources; hence it is vital to their economic survival. Nations all throughout the world rely on the water for trade and commerce. This article looks at the present condition of marine security in the Gulf of Guinea. The Gulf of Guinea has a total shoreline of about 5,000 nautical miles and several natural harbours with dangerous weather. It has a significant crude oil reservoir, as well as fish and other natural resources. These traits provide huge prospects for marine trade and transportation, but the Gulf of Guinea is also riddled with maritime crimes of all types, including piracy and smuggling. Maritime piracy has presented a threat to coastal states’ stability and economic viability all across the world, not only in Africa. The study examines sea piracy in general, the Geographic Information System, and the impact of maritime piracy on the world socioeconomic development using secondary data. It then goes on to provide a number of recommendations aimed at addressing the problems caused by maritime piracy in the Gulf of Guinea in order to improve maritime security.

Ocean Affects from Severe Weather Systems in Coastal Areas

Severe weather systems can generate large waves and storm surges which can cause many fatalities in coastal areas. In extreme circumstances a single cyclone caused up to 500,000 fatalities in the Bay of Bengal in 1970. Adaption by authorities in that region from evacuations and construction of storm shelters have significantly reduced the number of such fatalities there. The effects of Hurricane Sandy in 2012 in New York City and surrounding areas is examined to show how ocean effects can cause many casualties. Scrutiny of a European storm shows how a slight error in analysis can fail to detect a deadly increase in intensity which caused many fatalities. World record wave height events are examined, and the historical Australian east coast events are investigated. The impacts from long period waves emanating from distant storms are shown to be a forecasting problem.

Codon Usage of Chloroplast Gene rbcL in Laurencia sensu lato (Rhodophyta) species

Recent advances in molecular biology make it possible to sequence not only genes or genomes, but also to understand codon dynamics. For the organelle genes of these organisms, a small set of preferred codons are used for encoding proteins. For the first time, this paper treats the divergence of synonymous codon usage and its bias in the rbcL gene within the Laurencia complex of red algae. We observed that the synonymous codon preference biases in rbcL are large and differ among species. A clear distinction in codon usage between genera is evident: the genera Dasya and Delesseria use a set that fluctuated between 53 and 58 codons. Whereas, in the genera Ceramium, Chondrophycus, Chlamydomonas, Chlorella, Laurencia s.s, Osmundea, and Palisada codon usage indicates a higher restriction fluctuating between 40 to 51 codons. Laurencia complex genera and other representative algae showed a defined composition pattern, with lower percentage values of NNC/G (7-24.9%). Dasya and Delesseria showed a selective pattern tendency because of high percentage values of NNC/G (54-55%). The estimated codon bias parameters were tested to infer systematic relationships and match suitable codons with the NNC / G codon percentages. Cluster analysis based on Codon Usage supports phylogenetic relationships between Chondrophycus, Palisada, Laurencia, Osmundea, and Yuzurua species.

Hydrogeological and Hydrochemical Characterization of Coastal aquifers with Special reference to Submarine Groundwater Discharge in Uttara kannada, Karnataka, India

Submarine groundwater discharges to the coastal ecosystems have been recognised as a source of dissolved chemical substances that cause chemical and ecological effects on sea waters. Groundwater, in many coastal areas, becomes contaminated or at least enriched with a variety of chemical substances and can have higher concentrations of dissolved solids than river water. As a result SGD makes a larger contribution to the flux of dissolved chemical compounds than river run-off. Therefore, the present investigation has been carried out to understand the process of submarine groundwater discharge based on hydrological, hydrogeological and hydrochemical components. Accordingly water balance components were evaluated based on hydrological and hydrogeological investigations. Hydrochemical parameters were also evaluated to understand the impact of seawater intrusion during both pre-monsoon and post-monsoon seasons of 2019. Study revealed that, there are signatures of considerable quantity of submarine groundwater discharge in parts of Honnavara, Kumta, Ankola and Karwar talukas. The influence of seawater in coastal aquifers is quite rare all along the coast of Uttara kannada district which is attributed to high groundwater recharge(15-20%) occurring in catchment areas.

Journal of Marine Science: An Open Framework Dedicated to the Presentation of the Discoveries and Insights in Marine Science Research

Marine environment represents a very important and actual topic. Water bodies cover more than two thirds of the earth’s surface and even after thousands of years, scientists have yet to fully uncover their mysteries. At the same time climate, change has visible effects with a growing dynamics in the last decades and the marine environment is very sensitive to these changes. In order to mitigate the effects of the climate change there is an increasing need of reducing the CO2 emissions and from this perspective the marine environment represents an important source of clean renewable energy. In this respect, the Journal of Marine Science represented even from the beginning an open framework dedicated to the presentation of the discoveries and insights in marine science research.