Effects of antifouling technology application on Marine ecological environment

Resolving the contradiction between Marine economic development and Marine ecological environment protection has become an unavoidable and sharp problem. The uncontrolled use of Marine antifouling technology will bring uncontrollable and even irreversible damage to the Marine biosphere, which will lead to ecological disaster and threaten the survival of human beings. Therefore, it is an urgent task to find antifouling technology with lower environmental toxicity under the premise of considering economy. More attention should be paid to the long-term impact of mature and new technologies on the Marine ecological environment. This paper introduces the development status of antifouling technology, its influence on Marine ecological environment and puts forward the design strategy of comprehensive biological fouling prevention and control technology.

Thermocline Model for Estimating Argo Sea Surface Temperature

Argo has become an important constituent of the global ocean observation system. However, due to the lack of sea surface measurements from most Argo profiles, the application of Argo data is still limited. In this study, a thermocline model was constructed based on three key thermocline parameters, i.e, thermocline upper depth, the thermocline bottom depth, and thermocline temperature gradient. Following the model, we estimated the sea surface temperature of Argo profiles by providing the relationship between sea surface and subsurface temperature. We tested the effectiveness of our proposed model using statistical analysis and by comparing the sea surface temperature with the results obtained from traditional methods and in situ observations in the Pacific Ocean. The root mean square errors of results obtained from thermocline model were found to be significantly reduced compared to the extrapolation results and satellite retrieved temperature results. The correlation coefficient between the estimation result and in situ observation was 0.967. Argo surface temperature, estimated by the thermocline model, has been theoretically proved to be reliable. Thus, our model generates theoretically feasible data present the mesoscale phenomenon in more detail. Overall, this study compensates for the lack surface observation of Argo, and provides a new tool to establish complete Argo data sets.

Abundance and Distribution, Growth Pattern, Sex Ratio and Gonadosomatic Index (GSI) of Liza falcipinnis (Valenciennes, 1836) from Ojo Axis of Badagry Creeks, Lagos, Nigeria

A study on seasonal abundance, morphometric and meristic data, growth pattern, condition factor, sex ratio and gonadosomatic index of Liza falcipinnis (Valenciennes, 1836) from the Ojo axis of Badagry creek, Nigeria was conducted from May 2019 to March 2020. A total of 1012 species were randomly selected, having 499 females and 513 males. The length frequency analysis and length-weight relationships (LWR) were determined. Sex ratio was determined by Chi-square analysis. The results showed that morphometric data are: 0.5 - 2.5 mm for ED, 2.1 - 12 mm for HL, 1.7 - 8.1 mm for HD, 2.5 - 11.7 for BD, 2.6 - 233.3 mm for TL and 9.23 - 1006 g for BW for the combined sexes. The slope (b) shows an allometric growth pattern. The intercept ‘a’ and slope ‘b’ of the LWR (LogW = a + bLogL) were Log W=15.39+ 0.34 LogL (r= 0.54) for combined sexes, Log W= 12.49+ 0.02 log L (r= 0.38) for males and Log W= 18.23+ 0.01 log L (r=0.16) for females.The length frequency distribution indicated that species were dominated by two year classes (Ages 1 and 2). Condition factors were generally low. The values ranged between 0.68 - 0.85 for combined sexes. The gonadosomatic index for female was highest in August, 2019 (17.77%) with Mean±SD of 2.88±0.75; which indicated the peak of spawning period in the study area.Sex ratio difference was significant (P<0.05). Sexual differences were significant; the females are phenotypically larger than the male.

Status stock and Sustainable Management Measures for Moroccan Sardines

This article summarizes the state of stocks of sardine, sardina pilchardus in Moroccan waters at the end of 2016 and 2018. These stocks varies according to the region,They are now in a sustainable exploitation situation:Atlantic sardine, but also stocks that have reached or are still in over-exploitation levels: Mediterranean sardine. The fi shing pressure exerted on the sardine stock exceeds the optimal level by 40%. Due to the degradation of the fragile marine environment of the Mediterranean region, generated by pollution of various origins, the overexploitation of juveniles in the coastal strip, non-responsible practices and the use of non-fi shing gearselective, it is imperative to take the necessary measures to protect the marine environment and ensure rational and sustainable exploitation of the resource. (High commission plan 2006 report).

Present Status of Aquatic Resource and Its Catch of Mogra River in Bangladesh

Bangladesh is very rich in aquatic fauna with a biodiversity. The present study, conducted during 2015 to 2019, recorded a total number of 131 spe cies (104 fish, 09 prawn, 01 snail, 04 crabs, and 13 turtles) belonging to 26 families were identified from the Mogra River and its flood plain. About ten types of fishing gears, different crafts, hook and line were found oper ative in the river. Increasing rates of using current jal (16.0-26.40%) and Kapuri jal (11.0-16.70%) were identified as detrimental gears destroyingdifferent species. The fish productivity was decreased dramatically from 170.63±10.81mt to 134.75±8.02 mt with a decreasing percentage of 6.26 to 21.03% within five years. Three important aquatic species turtiles (Cyclemys oldhami, Melanocheelys trjuuga and Morenia petersi) became rare and 17 commercially important aquatic species were at the edge of extinction (critically endangered, CR). From the study, 67 species were recorded inthe endangered (EN) category, 20 species vulnerable status (VU), 11 species lower risk (LR), 07 species Least concern (LC) and 04 Data deficient (DF). To save the existing aquatic species in the studied riverine ecosystem and ensure better livelihood of the fishes, a team of local management committee, similar to the Hilsa fisheries management technology is needed.

On the Impact of Brazil's Largest Recent Oil Spill on Regional Oceans

In 2019, an oil spill in Brazil, of unknown origin, severely impacted coastal environs with the worst environmental disaster ever recorded in any tropical coastal region globally severely damaging South Pirangi Reef area in the state of Rio Grande do Norte (RN). Here we discuss acute and chronic impacts including chemical contamination and economic consequences all over the world and show some evidence of the oil spill in this biodiverse area. Moreover, the lapse between the moment of the disaster, and the action to manage it, was hampered by a political agenda coinciding with local and global tragedies that redirected public attention. Meanwhile almost 2 years have passed still without the offending party identification or culpability; and poor communities may continue to absorb its deleterious impacts for decades without consideration or compensation. This disaster occurred during the Brazilian government’s current issues involving extensive environmental mismanagement, resulting in a slow response from an inept system. It is with urgent necessity to spotlight this tragedy in this unique and sensitive reef habitat experiencing the ongoing damaging effects that include socio-economic losses not yet addressed.

Knowledge and Opportunities from the Plastisphere: A Prelude for the Search of Plastic Degrading Bacteria on Coastal Environments

Plastic pollution has become an urgent issue, since its invasion to every ecosystem has led to multiple impacts on the environment and human populations. Certain microbial strains and genera had shown the ability to biodegrade plastic sources under laboratory conditions. In this minireview, we collect and analyze scientific papers and reports of this microbial activity as we contextualize this information on the global plastic pollution problem, to provide an updated state of the art of plastic biodegradation with microbial agents. Along with a broad understanding of the general process of plastic biodegradation hosted by microorganisms. The contributions of this minireview come from the identification of research gaps, as well as proposals for new approaches. One of the main proposals focuses on coastal environments and in particular coastal wetlands as a great microbiome source with potential for plastic biodegradation, whether reported or undiscovered. Our final proposal consists of the application of this knowledge into technologic tools and strategies that have a remarkable impact on the battle against the plastic pollution problem.

A CFD Study of the Resistance Behavior of a Planing hull in Restricted Waterways

The demand for high-speed boats that operating near to shoreline is increasing nowadays. Understanding the behavior and attitude of high-speed boats when moving in different waterways are very important for boat designer. Usually, they using experimental model testing for resistance prediction and dynamic force but this method is high consuming time, and cost. When planing boats are moving at high speed, two forces participate in their support, they are the hydrodynamic lift created by the shape of the planing hull, and the lift force resulting from displacing part of the liquid (buoyancy force).This research uses a CFD (Computational Fluid Dynamics) analysis to investigate the shallow water effects on prismatic planing hull. The turbulence flow around the hull was described by Reynolds Navier Stokes equations RANSE using the k-ɛ turbulence model. The free surface was modelled by the volume of fluid (VOF) method. The analysis is steady for all the ranges of speeds except those close to the critical speed range Fh =0.84 to 1.27 due to the propagation of the planing hull solitary waves at this range. For this fluctuation in the results, the average numerical value of the results was taken to compare it with the experiment.In this study, the planing hull lift force, total resistance, and wave pattern for the range of subcritical speeds, critical speeds, and supercritical speeds have been calculated using CFD. The numerical results have been compared with experimental results. The dynamic pressure distribution on the planing hull and its wave pattern at critical speed in shallow water were compared with those in deep water.The numerical results give a good agreement with the experimental results whereas total average error equals 7% for numerical lift force, and 8% for numerical total resistance. The worst effect on the planing hull in shallow channels occurs at the critical speed range, where solitary wave formulates.

Application of Fourth Industrial Revolution Technologies to Marine Aquaculture for Future Food: Imperatives, Challenges and Prospects

This study was undertaken to examine the options and feasibility of deploying new technologies for transforming the aquaculture sector with the objective of increasing the production efficiency. Selection of technologies to obtain the expected outcome should, obviously, be consistent with the criteria of sustainable development. There is a range of technologies being suggested for driving change in aquaculture to enhance its contribution to food security. It is necessary to highlight the complexity of issues for systems approach that can shape the course of development of aquaculture so that it can live-up to the expected fish demand by 2030 in addition to the current quantity of 82.1 million tons. Some of the Fourth Industrial Revolution (IR4.0) technologies suggested to achieve this target envisage the use of real-time monitoring, integration of a constant stream of data from connected production systems and intelligent automation in controls. This requires application of mobile devices, internet of things (IoT), smart sensors, artificial intelligence (AI), big data analytics, robotics as well as augmented virtual and mixed reality. AI is receiving more attention due to many reasons. Its use in aquaculture can happen in many ways, for example, in detecting and mitigating stress on the captive fish which is considered critical for the success of aquaculture. While the technology intensification in aquaculture holds a great potential but there are constraints in deploying IR4.0 tools in aquaculture. Possible solutions and practical options, especially with respect to future food choices are highlighted in this paper.

Non-linearity Analysis of Ship Roll Gyro-stabilizer Control System

A gyro-stabilizer is the interesting system that it can apply to marine vessels for diminishes roll motion. Today it has potentially light weight with no hydrodynamics drag and effective at zero forward speed. The twin-gyroscope was chosen. Almost, the modelling for designing the system use linear model that it might not comprehensive mission requirement such as high sea condition. The non-linearity analysis was proved by comparison the results between linear and non-linear model of gyro-stabilizer throughout frequency domain also same wave input, constrains and limitations. Moreover, they were cross checked by simulating in time domain. The comparison of interested of linear and non-linear close loop model in frequency domain has demonstrated the similar characteristics but gave different values at same frequency obviously. The results were confirmed again by simulation in irregular beam sea on time domain and they demonstrate the difference of behavior of both systems while the gyro-stabilizers are switching on and off. From the resulting analysis, the non-linear gyro-stabilizer model gives more real results that correspond to more accuracy in a designing gyro-stabilizer control system for various amplitudes and frequencies operating condition especially high sea condition.