Natural Sea Research Articles

Natural sea water and artificial sea water are not equivalent in plastic leachate contamination studies

Natural sea water and artificial sea water are not equivalent in plastic leachate contamination studies

One-pot fabrication of open-spherical shapes based on the decoration of copper sulfide/poly-O-amino benzenethiol on copper oxide as a promising photocathode for hydrogen generation from the natural source of Red Sea water

Abstract Harnessing green hydrogen production from natural Red Sea water offers an innovative solution to address energy challenges. A one-pot fabrication method is used to create novel nanocomposite thin films with open-spherical shapes, utilizing copper sulfide/poly-O-amino benzenethiol decorated on copper oxide as a promising photocathode. After thorough analysis, a unique morphology characterized by open spherical shapes is projected, which contributes to improved optical absorption. The bandgap of the nanocomposite is 1.17 eV, enabling efficient absorption of light across the entire optical spectrum, extending up to 950 nm. Utilizing Red Sea water as an electrolyte, the generated J ph serves as an indicator of H2 gas production. The substantial J ph value of −0.82 mA cm−2 is achieved at −0.85 V under light illumination. Furthermore, J ph values exhibit variability, starting at −0.58 mA cm−2 (at 730 nm) and increasing to −0.75 mA cm−2 at a wavelength of 340 nm. The estimated hydrogen gas production rate reaches 1.5 µmole h−1 cm−2, translating to an impressive 15 µmole h−1 for every 10 cm². This remarkable rate underscores the effectiveness of the photocathode, especially given its fabrication through a single-step process that is suitable for mass production. In addition, its cost-effectiveness further enhances its appeal as a viable solution for renewable energy production for hydrogen gas generation from seawater.

Antifouling activity of PEGylated chitosan coatings: Impacts of the side chain length and encapsulated ZnO/Ag nanoparticles

PEGylation is regarded as a common antifouling strategy and the effect is normally linked with surface hydrophilicity of the coatings. Herein, the biopolymer chitosan (CS) was grafted by polyethylene glycol (PEG) of different chain lengths (molecular weight 200, 4 k and 100 k Da) to verify if the hydrophilicity of CS-PEG coatings is crucial in determining antifouling activities and if PEG chain length influences biofouling in marine environment. Properties of copolymers such as melting points and crystallinity are affected by grafting PEG. The water contact angle (WCA) of CS-PEG coatings increases with the chain length of grafted PEG, from 27° to 58°. Photocatalyst of zinc oxide-silver (ZnO/Ag) was also studied and its embedment (2 % to CS-PEG) renders the surface of CS-PEG coatings more hydrophobic with WCA increased from 52° to 86°. Antibacterial, anti-diatom, and anti-biofilm activities of the coatings were evaluated in natural sea water. The bacterial density on CS-PEG coatings was dramatically reduced to 4 × 104 compared to the control of 7 × 104 ind/mm2, and further to 2 × 104 for CS-PEG-ZnO/Ag coatings. CS-PEG coatings also strongly inhibit diatoms (120–200 ind/mm2), but the inclusion of ZnO/Ag did not obviously enhance such effect (50–150 ind/mm2). The findings provide useful insights for designing polymer-based antifouling coatings.

Drying trend in land and sea in East Asia during the warm season over the past four decades

Abstract The East Asian region is typically characterized by warm and humid conditions from late spring to summer. However, in recent decades, this region has experienced an increase in severe drying conditions, deviating from historical climatological patterns. This study investigated the precipitation-evaporation (P-E) trends across land and sea regions in East Asia (EA) during the extended summer season (April to September) from 1980 to 2022, and the key physical processes driving these trends through moisture budget decomposition and numerical experiments. The results reveal pronounced drying trends in southeastern China and the Yellow Sea and parts of the Korea Strait and Korean Peninsula over the past 43 years. The underlying physical processes driving these drying conditions differ between land and sea in EA. In southeastern China, the drying is driven by dynamic processes, particularly moisture divergence related to wind changes. This is linked to anomalous strengthening of descending motion due to the Indo-Pacific warm pool warming induced by both anthropogenic global warming and natural Pacific Decadal Oscillation-like sea surface temperature (SST) patterns. Conversely, drying in the Yellow Sea and adjacent areas is influenced by thermodynamic moisture advection. The altered humidity distribution due to global warming-induced SST patterns, which are higher over the Northwest Pacific marginal sea and lower in inland China, drives dry air transport from inland China to the Yellow Sea via background southwesterly wind. These findings enhance our understanding of the drying trend and their distinct processes in EA’s land and sea areas during the extended summer.

Eminent Red Sea water hydrogen generation via a Pb(ii)-iodide/poly(1H-pyrrole) nanocomposite photocathode

Abstract The development of a photocathode based on a Pb(ii)-iodide/poly(1H-pyrrole) porous spherical (PbI2/P1HP PS) nanocomposite has been successfully achieved in the efficient production of H2 gas from Red Sea water. The distinguishable spherical and porous shapes of these nanocomposites are characterized by a minimum surface measuring approximately 25 nm. This structural configuration, coupled with the nanocomposite’s substantial light absorbance, results in a modest bandgap of 2.4 eV. This turns the nanocomposite into a highly promising candidate for renewable energy applications, particularly for H2 gas generation from natural sources like Red Sea water. The economic viability of the PbI2/P1HP PS nanocomposite, relying on a glass substrate, mass production, and straightforward fabrication techniques, adds to its promising profile for H2 gas evolution. The photocathode exhibits significant potential for H2 gas production, with a notable current density (J ph) value of 1.0 mA·cm−2 in a three-electrode cell configuration. The IPCE reaches 3.1%, reflecting the successful evolution of 24 µmol·h−1 10 cm2 of the photocathode. Importantly, the use of natural Red Sea water as an electrolyte underscores a key feature for H2 gas production: utilizing freely available natural resources. This aspect holds considerable promise for industrial applications, emphasizing the environmentally sustainable nature of the photocathode.

Design, fabrication, and performance assessment for green hydrogen production unit

Creating and building an integrated system that consists of a storage tank, an electrolysis cell with many electrolyzer types, and a green hydrogen generator that produces clean, sustainable gas using solar photovoltaic (PV) energy and renewable energy sources. Three different electrolyzer modules with six, eleven, and twenty-one plates each were created locally and meant to be utilized in the production of green hydrogen. The hydrogen storage system's design was also created. It is clear that the maximum value of hydrogen production is recorded in the following ordered: KOH (5.5 L/min) > NaOH (1.2 L/min) > NaCl (0.7 L/min) > MgSO4 (0.4 L/min). Also, sea water was used as electrolyte solution with different dilution 5, 10, 15, and 20% using a natural sea water sample collected from the Mediterranean Sea. It is found that 15% sea water dilution reaches the maximum value of H2 production (3.4 L/min). Using distilled water and tap water, respectively, the volume of generated H2 gas reached its maximum value of 8 L/min and 6.5 L/min at 0.4 mols of KOH. It was observed that with increased time durations (0–90 min), enhance the rate of hydrogen production to be reaches 8.2 and 11.5 L/min when using 0.05 and 0.1 mols KOH, respectively. This approach reduces environmental effect and operational costs, providing a sustainable solution to the water and energy problems.

Pemanfaatan Sumber Daya Alam Pasir Laut sebagai Komoditas Tambang Masyarakat di Perairan Kabupaten Karimun, Kepulauan Riau

Potential mining commodities in Karimun Regency, Riau Islands Province, include: tin, granite, land sand and sea sand. Areas in Karimun Regency that have the potential for sea sand are Babi Island Waters, Meral District, Karimun Regency and Tulang Village Waters, Selat Gelam District, Karimun Regency. This study was carried out to measure the optimal level of utilization of natural sea sand resources that can guarantee its sustainability. This is done by measuring the level of availability of sea sand; and measuring available sea sand reserves, the level of utilization that does not erode reserves, as well as estimated supply projections for future needs. The method used is the observation method, by collecting field data. Data were analyzed descriptively, with bathymetry measurements, spatial analysis using Geographic Information Systems (GIS), and literature study. The resources of the Community Mining Area with sea sand as a commodity in area A of Babi Island waters are 1,174,626.58 m3 and the resources of the Community Mining Area in area B of Gelam Strait waters are 502,088.58 m3

Natural sea water and artificial sea water are not equivalent in plastic leachate contamination studies.

Plastic contamination is one of the concerns of our age. With more than 150 million tons of plastic floating in the oceans, and a further 8 million tons arriving to the water each year, in recent times the scientific community has been studying the effects these plastics have on sea life both in the field and with experimental approaches. Laboratory based studies have been using both natural sea water and artificial sea water for testing various aspects of plastic contamination, including the study of chemicals leached from the plastic particles to the water. We set out to test this equivalence, looking at the leaching of heavy metals form plastic particles. We obtained leachates of polyvinyl chloride plastic pre-production nurdles both in natural and artificial sea water and determined the elements in excess from untreated water by Inductively coupled plasma - optical emission spectrometry. We then used these different leachates to assess developmental success in the tunicate Ciona intestinalis by treating fertilised eggs through their development to hatched larvae. Here we report that chemical analysis of polyvinyl chloride plastic pre-production pellet leachates shows a different composition in natural and artificial sea water. We find that the zinc leaching from the plastic particles is up to five times higher in natural seawater than in artificial seawater, and this can have an effect in the toxicological studies derived. Indeed, we observe different effects in the development of C. intestinalis when using leachates in natural or artificial sea water. We also observe that not all artificial sea waters are suitable for studying the development of the tunicate C. intestinalis. Our results show that, at least in this case, both types of water are not equivalent to produce plastic leachaetes and suggest that precaution should be taken when conclusions are derived from results obtained in artificial sea water.

Promising porous spherical PbI2/poly-2-aminobenzenethiol nanocomposite as a photocathode for hydrogen generation from Red Sea water

A highly efficient porous spherical nanocomposite photocathode, known as PbI2/poly-2-amino benzene thiol (PbI2/P2ABT), is created through a two-step reaction process involving the oxidation of 2-amino benzene thiol with iodine, followed by a double displacement reaction. The resulting nanocomposite displays outstanding morphology, comprising spherical particles with a diameter of 500 nm and featuring nanoscale porosity with pore sizes around 5 nm. Notably, the hydrogen production estimate reaches 9.6 μmole/h·10 cm2, a promising outcome attributed to the environmentally friendly and cost-effective use of natural Red Sea water. The quantification of hydrogen gas is accomplished by assessing the photogenerated carriers using the current density relationship. The calculated Jph value experiences a substantial increase to −0.122 mA.cm−2 compared to a minimal 0.07 mA.cm−2 in the absence of light. Furthermore, the optical assessment reveals exceptional Jph values under 340 nm, reaching 0.121 mA.cm−2, which extends to the visible spectrum with a value of 0.112 mA.cm−2. The remarkable features of this nanocomposite include its cost-effectiveness, ease of fabrication, and scalability for mass production. These qualities collectively enable the conversion of Red Sea water into hydrogen gas, offering a practical and efficient solution aligned with eco-friendly and economically viable practices. This nanocomposite shows significant potential for advancing clean energy technologies and contributing to sustainable hydrogen production from natural water sources.

DESAIN DAN PEMBUATAN PROTOTIPE CARLSON SURGE DEVICE (CSD) UNTUK BUDIDAYA KARANG HIAS

As the interest in marine aquariums increases, so does the demand for ornamental corals. One of the parameters needed for coral growth is water flow. The Carlson Surge Device (CSD) is a tool that can generate water currents similar to natural sea currents found in coral reefs. This research aims to create a CSD that is easy and inexpensive to produce, so it can be widely applied in ornamental coral cultivation tanks by the community. By optimizing the cultivation of ornamental corals, it is hoped that the damage to coral reef ecosystems caused by illegal coral harvesting in nature can be minimized. This research uses an experimental method by testing PVC pipe diameters of 1 inch, 1.5 inches, 2 inches, and 2.5 inches. The CSD design created has reservoir dimensions with a diameter of 36 cm and a height of 35 cm, and uses PVC pipes with an inner pipe length of 20 cm and an outer pipe length of 44 cm. The results of this study show that the use of 2.5-inch diameter PVC pipes can produce a water flow rate of 0.28 m/s, which is suitable for coral growth, while the water flow produced by other pipe diameters is still too strong. These results indicate that the CSD prototype that has been made is suitable for application in ornamental coral cultivation tanks.

Anthropogenic activity shapes the assemble and co-occurrence pattern of microbial communities in fishing harbors around the Bohai economic circle

This study aimed to elucidate the effects of coastal environmental stress on the composition of sediment bacterial communities and their cooccurrence patterns in fishing harbors around the Bohai Economic Circle, China. Compared with the natural sea area, fishing harbors contained higher levels of organic pollution (organic pollution index = 0.12 ± 0.026) and considerably reduced bacterial richness and evenness. The distributions of sediment microbial communities clustered along the pollutant concentration gradients across fishing harbors. Betaproteobacteria dominated (76%) organically polluted fishing harbors, which were mostly disturbed by anthropogenic activities. However, the harbors also revealed the absence of numerous pathogenic (Coxiella and Legionella) and photosynthetic (Synechococcus and Leptolyngbya) bacteria. Abundant genera, including Thiobacillus and Arenimonas, exhibited a positive correlation with total phosphorus and a negative correlation with total nitrogen in sediments. Meanwhile, Sulfurovum, Psychrobacter, and Woeseia showed the opposite trend. Pollutant accumulation and anthropogenic activities caused the decrease in the sediment microbial diversity and dispersal ability and promoted convergent evolution. Severely polluted harbors with simplified cooccurrence networks revealed the presence of destabilized microbial communities. In addition, the modularity of bacterial networks decreased with organic pollution. Our results provide important insights into the adjustment mechanism of microbial communities to community organization and functions under environmental pollution stress. Overall, this study enhanced our understanding of how microbial communities in coastal sediments adapted and survived amidst anthropogenic activities like oily effluent discharges from large ships, wash water, domestic sewage, garbage, and fisheries wastes. It also examined their resilience to future contamination.

Methane plume detection after the 2022 Nord Stream pipeline explosion in the Baltic Sea

On September 26th, 2022, the detonations at the gas pipelines Nord Stream 1 and 2 resulted in some of the largest non-natural releases of methane known. The distribution of methane in the surrounding seawater and the possible effects were not apparent. To trace the pathways of methane we recorded CH4 concentrations and the isotopic signal (δ13C-CH4) in seawater, and air. A week post-explosion, we detected methane concentrations up to 4 orders of magnitude above the natural Baltic Sea background. The released fossil methane created a distinct plume with δ13C-CH4 ratios differing from natural background values. The strong water stratification preserved the distribution pattern initiated by the explosion, shown by the laterally strong concentration gradient within the plume. Our analysis encompasses three stages of the explosion's impact; the initial sea-air methane release, measurements taken during our research expedition one week later, and a third stage triggered by the shift from summer to winter conditions as an outlook on how winter mixing and microbial activity will influence the plume.

A temporal prediction model for ship maneuvering motion based on multi-head attention mechanism

In real-world maritime conditions, accurately predicting ship maneuvering motion over ultrashort periods can enhance the development of more precise vessel control algorithms. This study proposes a prediction model for ship maneuvering that utilizes a multi-head attention mechanism. To form a basis for this data-driven approach, we gathered training data from turning and zigzag tests of a ship conducted in natural sea environments. The model's predictive capability is assessed by comparing two strategies over a fixed 30-time-step forecast horizon: iterative multi-step forecasting (IMS) and direct multi-step forecasting (DMS). Notably, the model employs distinct attention layers to examine the temporal relationships among various motion variables across the three degrees of freedom in the output. Moreover, it uses separate attention layers to explore the distinct time response traits of the input motion states and control signals. The results demonstrate that different motion state variables display unique temporal correlations under different signal sequences, and the proposed network architecture effectively captures these temporal response traits.

Floating wind turbine response in uni- and multi-directional nonlinear waves by numerical and experimental investigations

Natural sea waves are typically multi-directional. However, the existing studies on the interaction of waves and structures mostly concentrate on uni-directional waves. In this study, using a higher-order boundary element method based on the nonlinear potential flow theory and the perturbation expansion technique, a numerical model is developed to investigate the hydrodynamic performance of a semi-submersible wind turbine foundation in uni- and multi-directional waves. Comprehensive validations with the wave-tank experiment are conducted. It is found that the significant platform response increases with the peak wave period in uni-directional irregular waves, while the high-frequency “energy” ratio changes little. The significant wave height hardly influences motion responses from either the time- or the frequency-domain perspective. In multi-directional irregular waves, the translational motions exhibit monotonicity with wave directionality. The energy concentration around the primary direction leads to a dominant wave-frequency motion and an increase in the high-frequency “energy” ratio. Although the individual modal motion responses are variable functions of wave nonlinearity, their averaged translational and rotational motions are nearly constant, indicating an energy transition or a trade-off relationship among the modal motions. In addition, unlike the uni-directional wave case, the low- and high-frequency “energy” ratios increase quadratically and decrease linearly with the significant wave height in multi-directional waves, respectively. All these findings demonstrate that wave directionality can change the wave–structure interaction properties and therefore needs to be adequately considered in engineering applications.

Enhanced Hydrogen Evolution in Porous and Hybrid g‐C3N4/Pt‐PVDF Electrospun Membranes via Piezoelectricity from Water Flow Energy

AbstractInspired from seaweed swayed by waves, the enhanced hydrogen evolution is realized in porous and hybrid g‐C3N4/Pt‐PVDF electrospun membranes via piezoelectricity from water flow energy. The membranes are fabricated by dispersing g‐C3N4/Pt into the mixed solution of PVDF and PEO, followed by electrospinning and selective removal of PEO. By changing the PEO amount, the pore size in nanofibers is adjusted. Due to the hydrogen bonding between g‐C3N4/Pt and PVDF, the β phase of PVDF is increased, beneficial for the piezoelectricity performance. When the electrospun membranes are exposed to water flow, an additional potential field is triggered due to the deformation of PVDF. It not only eases the photogeneration of charge carriers from g‐C3N4/Pt but also hinders their recombination. The prolonged lifetime significantly improves the photocatalytic water splitting of g‐C3N4/Pt under visible light. The hydrogen evolution in the electrospun membranes (PVDF to PEO = 4:1) is profoundly improved to 9 278 µmol h−1 g−1, almost doubled to the pure g‐C3N4/Pt nanosheets (5 220 µmol h−1 g−1). Therefore, the seaweed‐inspired electrospun membrane is a promising strategy for the efficiently photocatalytic water splitting via g‐C3N4 in an aqueous environment, such as a natural sea and lake, by the piezoelectricity gained from the water flow energy.

Costs of Dust Collection by Trichodesmium: Effect on Buoyancy and Toxic Metal Release

AbstractThe marine cyanobacterium Trichodesmium has the remarkable ability to interact with and utilize air‐borne dust as a nutrient source. However, dust may adversely affect Trichodesmium through buoyancy loss and exposure to toxic metals. Our study explored the effect of desert dust on buoyancy and mortality of natural Red Sea puff‐shaped Trichodesmium thiebautii. Sinking velocities and ability of individual colonies to stay afloat with increasing dust loads were studied in sedimentation chambers. Low dust loads of up to ∼400 ng per colony did not impact initial sinking velocity and colonies remained afloat in the chamber. Above this threshold, sinking velocity increased linearly with the colony dust load at a slope matching prediction based on Stoke's law. The potential toxicity of dust was assessed with regards to metal dissolution kinetics, differentiating between rapidly released metals, which may impact surface blooms, and gradually released metals that may impact dust‐centering colonies. Incubations with increasing dust concentrations revealed colony death, but the observed lethal dose far exceeded dust concentrations measured in coastal and open ocean systems. Removal of toxic particles as a mechanism to reduce toxicity was explored using SEM‐EDX imaging of colonies incubated with Cu‐minerals, yet observations did not support this pathway. Combining our current and former experiments, we suggest that in natural settings the nutritional benefits gained by Trichodesmium via dust collection outweigh the risks of buoyancy loss and toxicity. Our data and concepts feed into the growing recognition of the significance of dust for Trichodesmium's ecology and subsequently to ocean productivity.

Natural sea water and artificial sea water are not equivalent in plastic leachate contamination studies

Background Plastic contamination is one of the concerns of our age. With more than 150 million tons of plastic floating in the oceans, and a further 8 million tons arriving to the water each year, in recent times the scientific community has been studying the effects these plastics have on sea life both in the field and with experimental approaches. Laboratory based studies have been using both natural sea water and artificial sea water for testing various aspects of plastic contamination, including the study of chemicals leached from the plastic particles to the water. Methods We obtained leachates of PVC plastic pre-production nurdles both in natural and artificial sea water, and determined the elements in excess from untreated water by Inductively coupled plasma – optical emission spectrometry. We then used these different leachates to assess developmental success in the tunicate Ciona intestinalis by treating fertilised eggs through their development to hatched larvae. Results Here we report that chemical analysis of PVC plastic pre-production pellet leachates shows a different composition in natural and artificial sea water. We find that the Zn leaching from the plastic particles is reduced up to five times in artificial sea water, and this can have an effect in the toxicological studies derived. Indeed, we observe different effects in the development of C. intestinalis when using leachates in natural or artificial sea water. We also observe that not all artificial sea waters are suitable for studying the development of the tunicarte C. intestinalis. Conclusions Our results show that, at least in this case, both types of water are not equivalent to produce plastic leachaetes and suggest that precaution should be taken when conclusions are derived from results obtained in artificial sea water.

Assessing the sensitivity of aerosol mass budget and effective radiative forcing to horizontal grid spacing in E3SMv1 using a regional refinement approach

Abstract. Atmospheric aerosols have important impacts on air quality and the Earth–atmospheric energy balance. However, as computing power is limited, Earth system models generally use coarse spatial grids and parameterize finer-scale atmospheric processes. These parameterizations and the simulation of atmospheric aerosols are often sensitive to model horizontal resolutions. Understanding the sensitivities is necessary for the development of Earth system models at higher resolutions with the deployment of more powerful supercomputers. Using the Energy Exascale Earth System Model (E3SM) version 1, this study investigates the impact of horizontal grid spacing on the simulated aerosol mass budget, aerosol–cloud interactions, and the effective radiative forcing of anthropogenic aerosols (ERFaer) over the contiguous United States. We examine the resolution sensitivity by comparing the nudged simulation results for 2016 from the low-resolution model (LR) and the regional refinement model (RRM). As expected, the simulated emissions of natural dust, sea salt, and marine organic matter are substantially higher in the RRM than in the LR. In addition, RRM simulates stronger aqueous-phase production of sulfate through the enhanced oxidation of sulfur dioxide by hydrogen peroxide due to increased cloud liquid water content. In contrast, the gas-phase chemical production of sulfate is slightly suppressed. The RRM resolves more large-scale precipitation and produces less convective precipitation than the LR, leading to increased (decreased) aerosol wet scavenging by large-scale (convective) precipitation. Regarding aerosol effects on clouds, RRM produces larger temporal variabilities in the large-scale liquid cloud fractions than LR, resulting in increased microphysical cloud processing of aerosols (more interstitial aerosols are converted to cloud-borne aerosols via aerosol activation) in RRM. Water vapor condensation is also enhanced in RRM compared to LR. Consequently, the RRM simulation produces more cloud droplets, a larger cloud droplet radius, a higher liquid water path, and a larger cloud optical depth than the LR simulation. A comparison of the present-day and pre-industrial simulations indicates that, for this contiguous United States domain, the higher-resolution increases ERFaer at the top of the model by about 12 %, which is mainly attributed to the strengthened indirect effect associated with aerosol–cloud interactions.

Success Factors and Challenges: Implications of Real Options Valuation of Constructed Wetlands as Nature-Based Solutions for Wastewater Treatment

Constructed wetlands (CWs) are engineered water treatment systems that mimic the features and functions of natural wetlands. As a nature-based solution (NBS) for wastewater treatment, CWs are sustainable and cost-effective while providing various ecosystem services. However, their widespread application faces several uncertainties, particularly in developing countries. This study aims to analyze the success factors and challenges in implementing CW projects. Using the case of successful CWs in Bayawan City in the Philippines, this study surveyed 270 household heads from the community benefiting from the CWs and interviewed various CW stakeholders, including the project planner, management, community leader, social workers, and CW workers. The results showed that 89% of the respondents were aware of the existence of CWs in the community and 73% believed in their long-term sustainability. Among the identified factors for the successful implementation of the CW project were government support (43%), good governance (32%), and public support (14%). On the other hand, the implementation was challenged by improper maintenance (63%), overcrowding in the community (11%), foul smells (4%), funding (4%), and climate-related uncertainties, including natural calamities (4%), flooding (7%), earthquakes (4%), and sea level rise (11%). The implications of these success factors and challenges were discussed in the application of real options valuation to CW projects by incorporating the identified uncertainties into flexible decision making in the scaling up and widespread implementation of a more sustainable NBS to water resources management.

Influence of Pediveliger Larvae Stocking Density on Settlement Efficiency and Seed Production in Captivity of Mytilus galloprovincialis in Amsa Bay, Tetouan.

In mussel hatchery systems, the settlement process is a crucial element influencing seed yield. The current study assayed the influence of five densities of competent pediveliger larvae on settlement success and post-larvae production. We showed an inverse relationship between density and settlement efficiency, e.g., an attachment success of 99.4% at the lowest density (35 larvae/cm2) but only 9% at the highest density (210 larvae/cm2). However, post-larvae production was higher at intermediate larvae densities (70 larvae/cm2). The reimplementation of treatments upon post-larvae density after 6 weeks post settlement showed that the lowest-density groups bore both the highest post-larvae growth rate (22.24 ± 4.60 µm/day) and the largest head batch (48% of the size distribution), as compared to the higher-post-larvae-density groups. These results highlight the importance of optimizing both pediveliger larvae density and post-larvae density, to maximize high-quality seed yield in local hatcheries. Current rearing technologies would assure a timely commercial seed production to protect natural sea rocky beds in Alboran Sea coasts.