Marine Biology Research Articles

Internationalization of EIA rules in the BBNJ Agreement: Impediments and possible solutions

The International Legal Agreement for the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction (BBNJ Agreement) has been launched. The final agreement emphasizes that states are obliged to conduct Environmental Impact Assessment (EIA), providing more discretion to states that control planned activities. However, the EIA under the BBNJ negotiations, as well as the principles of international environmental law, customary international law and international organizations all call for the internationalization of the EIA and the restraint of states’ power and activities in areas beyond national jurisdiction (ABNJ). Therefore, an internationalized EIA system that subjects the state-led EIA process to global oversight or guidance is imperative. To demonstrate the necessity of EIA’s internationalization, this article analyses it from the multiple perspectives of international law and its significance to the BBNJ Agreement. Furthermore, the article examines the submissions of the Parties to the BBNJ Agreement and indicates that there is still an opportunity to internationalize the EIA system. The article concludes with recommendations that include the use of soft law documents, the internationalization of EIA guidance through list of activities, as well as the internationalization of EIA oversight through the process of public notification and consultation and rules on responsibility and liability.

Spatio-temporal dynamics of the carbonate system during macroalgae farming season in a semi-closed bay in southeast China

Ocean Negative Carbon Emission (ONCE) involves utilizing natural marine chemistry and biology, along with mariculture, to achieve carbon sink goals. Growing awareness of the interplay between aquaculture and the coastal carbonate system has drawn researchers’ attention amid ring CO2 concentrations and the negative impacts of aquaculture on the environment. In this study, twelve sites representing different maricultural types were selected, including macroalgae, shellfish, fish, and non-farming areas. The environmental factors, dissolved inorganic carbon (DIC), total alkalinity (TA), and pCO2, were measured monthly during kelp farming periods. Nitrate is a major component of total nitrogen, and the NO3-N concentration in the macroalgal culture zone was lower than others, indicating effective nitrogen removal by macroalgae aquaculture. TA and DIC in non-farmed areas demonstrated larger variation ranges than in farming areas, probably due to the effects of precipitation on salinity. Aquaculture activities effectively maintained TA and DIC, with macroalgae cultivation playing an important role in TA stability, potentially resisting acidification. The pCO2sea-air of macroalgae culture areas in spring was slightly negative, suggesting carbon sink potential. However, further research is needed to assess the full extent of this “fourth type” of blue carbon, including accurate carbon footprint calculation and the contributions of particulate organic carbon and recalcitrant dissolved organic carbon. This study provided insight into the comprehensive contribution of different aquaculture types to the fishery environment and carbonate system, which can help guide aquaculture management and facilitate the carbon-neutral transition of aquaculture.

Strategic environmental assessment in areas beyond national jurisdiction: existing regimes, challenges, and prospects

As a system based on domestic law, strategic environmental assessment (SEA) can take environmental factors into consideration in the formulation of policies, plans, and programmes, and has received much attention in the field of environmental governance of areas beyond national jurisdiction (ABNJ). The recently adopted “Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction” (BBNJ Agreement) incorporates SEA into its text, but the BBNJ Agreement has not yet entered into force. Of other existing schemes governing ABNJ, some lack provisions on SEA, and some do not set SEA as a binding legal obligation. Conducting SEA in ABNJ faces several challenges, including fragmented rules and reluctance on the part of countries, which lead to unsatisfactory results. Therefore, this study suggests that the BBNJ Agreement should collaborate with regional treaties and international organizations in the future to complement and reinforce current systems and regulations, improving compatibility among them. At the same time, consideration should be given to identifying the protection of BBNJ as a common concern of humankind (CCH) to strengthen the implementation of future SEAs.

COMPLEX RESEARCH EXPEDITION “CRILLON 2023”: FIRST FINDINGS AND PRELIMINARY RESULTS

In August 2023, a comprehensive expedition “Crillon 2023” was performed, covering both terrestrial and marine biotopes in the southeastern part of the Crillon Peninsula (Sakhalin Island, Russia). A group of specialists carried out field work in ichthyology, invertebrate zoology, entomology, botany, lichenology, bryology, mycology, parasitology, microbiology and marine biology. In the scarcely studied territory of the southeastern part of the peninsula, a notable amount of data on species diversity was collected, including more than 200 species of plants, 101 species of lichens, 74 species of mosses, 117 species of basidial macromycetes were recorded. Marine coastal communities of the littoral and sublittoral zones were studied, and diving methods were exploited. As many as 119 species of invertebrates and 20 species of seaweed have been recorded. Information was collected on 20 species of fish, including data on helminth infestation. Parasitological studies included the search for microsporidia in all available animal hosts, as well as the search for root crayfish - parasites of arthropods. Among the animals and plants found, there are rare and endangered species included in the regional and federal Red Books, as well as those previously not recorded for Sakhalin. The preliminary results obtained indicate great potential for further study of the eastern part of the peninsula from the standpoint of biological sciences, as well as the prospects for establishment a biological station in this area for long-term research and development.

Global biogeography of microbes driving ocean ecological status under climate change

Microbial communities play a crucial role in ocean ecology and global biogeochemical processes. However, understanding the intricate interactions among diversity, taxonomical composition, functional traits, and how these factors respond to climate change remains a significant challenge. Here, we propose seven distinct ecological statuses by systematically considering the diversity, structure, and biogeochemical potential of the ocean microbiome to delineate their biogeography. Anthropogenic climate change is expected to alter the ecological status of the surface ocean by influencing environmental conditions, particularly nutrient and oxygen contents. Our predictive model, which utilizes machine learning, indicates that the ecological status of approximately 32.44% of the surface ocean may undergo changes from the present to the end of this century, assuming no policy interventions. These changes mainly include poleward shifts in the main taxa, increases in photosynthetic carbon fixation and decreases in nutrient metabolism. However, this proportion can decrease significantly with effective control of greenhouse gas emissions. Our study underscores the urgent necessity for implementing policies to mitigate climate change, particularly from an ecological perspective.

Developing a sustainable resin for 3D printing in coral restoration

Coral reefs boast one of the planet’s most diversified ecosystems, serving as an essential source of food and revenue for millions of people while providing shelter to a wide variety of marine creatures. However, overfishing, pollution, climate change, and other factors collectively pose an escalating danger to coral reefs. Therefore, coral reef restoration efforts are urgently needed to save corals. In this study, we exploited 3D printing technology based on vat polymerization to fabricate artificial coral plugs, expediting the reef restoration process while minimizing labor costs. We have developed a scalable model through the photoinitiated polymerization of an eco-friendly resin composed of modified soybean oil and calcium carbonate which has the potential to significantly enhance global restoration efforts. Material characterization demonstrated that the printed scaffold was highly cross-linked. Based on cytotoxicity analysis, the printed scaffold exhibited excellent cell adhesion and proliferation characteristics. The coral microfragmentation experiment showed initial signs of coral settlement on the printed coral plugs. This work demonstrates that plant-based material and vat-polymerization-based 3D printing techniques hold promise for coral restoration.

Slow biological microplastics removal under ocean pollution phase-out trajectories

Microplastics are ubiquitous in marine environments and can be incorporated into biological aggregates including marine snows and faecal pellets. These aggregates are suspected to be a major removal mechanism for microplastics from the surface ocean, transporting them to deeper levels and the seafloor as they sink and remineralise. However, simple budget calculations, observations, and model parameter testing suggest that aggregation might also lead to retention of microplastics in the upper ocean, sustaining contamination in biologically-productive environments. The ability of the biological microplastic sink to reduce water column contamination has relevance to the setting of ocean plastics pollution reduction targets, as are currently under negotiation by the International Negotiating Committee of the United Nations Environment Assembly (UNEA). Here we apply eight idealised global pollution reduction trajectories, from 1%–100% per year, starting from the year 2026 and ending in the year 2100 to an Earth System Climate Model with a representation of ocean microplastics and their aggregation in biological particles. We find that the global ocean microplastic inventory and surface concentrations stabilize within this century for reduction rates exceeding 5% per year but the inventory does not substantially decrease under any trajectory. Furthermore, microplastics are retained by marine biology in the surface ocean, where concentrations stabilise to a non-zero value over decades. Lastly we find that irrespective of scenario, contamination of deeper ocean layers continues to increase for the duration of our simulations via the export of microplastics by biological aggregates. These results suggest that ambitious targets for pollution reduction exceeding 5% per year will be required to progress the resolution of the UNEA to ‘end plastic pollution’ in this century, and that ongoing microplastic contamination of the marine food web may be unavoidable.

Rutger Rosenberg: A pioneering marine ecologist.

Rutger Rosenberg: A pioneering marine ecologist.

The biophysics of water in cell biology: perspectives on a keystone for both marine sciences and cancer research.

The biophysics of water, has been debated over more than a century. Although its importance is still underestimated, significant breakthroughs occurred in recent years. The influence of protein condensation on water availability control was documented, new findings on water-transport proteins emerged, and the way water molecules rearrange to minimize free energy at interfaces was deciphered, influencing membrane thermodynamics. The state of knowledge continued to progress in the field of deep-sea marine biology, highlighting unknown effects of high hydrostatic pressure and/or temperature on interactions between proteins and ligands in extreme environments, and membrane structure adaptations. The role of osmolytes in protein stability control under stress is also discussed here in relation to fish egg hydration/buoyancy. The complexity of water movements within the cell is updated, all these findings leading to a better view of their impact on many cellular processes. The way water flow and osmotic gradients generated by ion transport work together to produce the driving force behind cell migration is also relevant to both marine biology and cancer research. Additional common points concern water dynamic changes during the neoplastic transformation of cells and tissues, or embryo development. This could improve imaging techniques, early cancer diagnosis, and understanding of the molecular and physiological basis of buoyancy for many marine species.

LOW-CRESTED AND EMERGENT BREAKWATERS WITH ECO-FRIENDLY ARMOUR UNITS

Artificial coastal defense systems (such as concrete armour units) frequently host less diverse aquatic populations than natural environments and feature higher concentrations of invasive species (Dafforn et al., 2009). Therefore, coastal structures need to be designed or refitted to achieve sustainable goals through the application of ecological engineering solutions applied to coastal defence structures and for the ecosystem, marine habitat, and biodiversity improvement. Ecological engineering, which integrates ecosystems with engineering principles to construct coastal structures that benefit both humans and the ecosystem, is growing as a means of reducing the adverse ecological impacts of coastal infrastructure (Mitsch & Jorgensen, 2003). Thus, creating new eco-friendly breakwater design guidelines is critical and will benefit from the multidisciplinary involvement of marine biologists and ecologists. The purpose of this experimental modelling study was to provide data on the hydraulic performance and stability of low-crested and emergent rubble mound breakwaters (RMBW) constructed using ecologically friendly armour units under various wave conditions. The University of Ottawa, the National Research Council of Canada (NRC), and ECOncrete collaborated to develop and conduct the physical testing program. Several breakwater models were tested to evaluate their performance, as the idea of an eco-friendly breakwater is still a new area of research. Thus, this experimental program is essential to promote environmentally-friendly armour units in the design of new coastal structures (such as Baker et al., 2018), as well as ecological retrofitting of existing coastal structures. The physical tests were conducted between June 2023 and August 2023 in the Large Wave Flume of NRC’s Ocean, Coastal, and River Engineering Research Center in Ottawa, Canada. ECOncrete's Coastalock armour units were tested in various configurations at a 1/15 scale using two-dimensional low-crested and emergent RMBW models. The hydraulic performance and failure mechanisms of these environmentally-friendly breakwater models were tested under severe wave conditions.

Ocean waves in the southwestern Atlantic Ocean: An evaluation of global wave models

AbstractIn situ wave observations are essential for implementing coastal management strategies, designing coastal and offshore structures and understanding many processes related to sedimentology and marine biology. Despite their importance, these observations are rather scarce in the coastal areas of southeastern South America. Moreover, the existing observations are discontinuous, with several gaps and no simultaneity. Today, global wave models have improved their performance by providing reliable wave parameters with high resolution and coverage even at near‐shore areas. In this work, wave parameters from five global models were compared with significant wave heights (HS), peak periods (T) and propagation direction at nine sites located at the Southwestern South Atlantic Ocean. The global products used were WAVERYS (Global Reanalysis Wav 001 032), IOWAGA (WAVEWATCH III Hindcast – WW3 – Global grid – CFSR), ERA5 (ECMWF reanalysis), NOAA WW3 – 30‐year Hindcast Phase 2 and NCEP/EMC Operational global wave model GFS – Wave. Mean arithmetic error (Bias), root mean square deviation, scatter index and the Pearson linear correlation coefficient (r) were assessed at each location where wave observations were available. The best agreements for HS were obtained at the deepest sites located farther from the coast. Lower statistical metrics were achieved at coastal sites where the bathymetry is roughly represented by the global models. The calculated correlation coefficients were found to be lower for T than for HS. Overall, T was slightly underestimated by global models. Wave propagation directions were excellently represented by global models at offshore sites. The WAVERYS model is the global product that best represents the wave parameters in the study area, probably due to its higher spatial resolution (0.2°) and more realistic atmospheric forcing (ERA5). In addition, it satisfactorily represents the temporal variability of HS in open water as well as swell characteristics at the outer the Río de la Plata.

PDNA-tachyplesin treatment stimulates the immune system and increases the probability of apoptosis in MC4-L2 tumor cells.

Breast cancer is the most common cancer among women worldwide, and marine creatures are the most abundant reservoir of anticancer medicines. Tachyplesin peptides have shown antibacterial capabilities, but their potential to inhibit cancer growth and trigger cancer cell death has not been investigated. A synthetic tachyplesin nucleotide sequence was generated and inserted into the pcDNA3.1( +) Mammalian Expression Vector. PCR analysis and enzyme digesting procedures were used to evaluate the vectors' accuracy. The transfection efficiency of MCF-7 and MCF10-A cells was 57% and 65%, respectively. The proliferation of MCF-7 cancer cells was markedly suppressed. Administration of plasmid DNA (pDNA) combined with tachyplesin to mice with tumors did not cause any discernible morbidity or mortality throughout treatment. The final body weight curves revealed a significant reduction in weight among mice treated with pDNA/tachyplesin and tachyplesin at a dose of 100 µg/ml (18.4 ± 0.24 gr, P < 0.05; 11.4 ± 0.24 gr P < 0.01) compared to the control group treated with PBS (22 ± 0.31 gr). Animals treated with pDNA/tachyplesin and tachyplesin exhibited a higher percentage of CD4 + Foxp3 + Tregs, CD8 + Foxp3 + Tregs, and CD4 + and CD8 + T cell populations expressing CTLA-4 in their lymph nodes and spleen compared to the PBS group. The groups that received pDNA/tachyplesin exhibited a substantial upregulation in the expression levels of caspase-3, caspase-8, BAX, PI3K, STAT3, and JAK genes. The results offer new possibilities for treating cancer by targeting malignancies using pDNA/tachyplesin and activating the mTOR and NFκB signaling pathways.

Archipelagic Stories, Anguilliform Resistances

This article addresses the persistent anthropocentric bias of archipelagic studies. It asks: What would it mean to invite more-than-human and transspecies perspectives into our theorizations of archipelagoes? This interrogation is addressed by following the meanderings of the eel—famously recognized as “the most mysterious creature in the natural world”—through two Francophone texts arising from the Indian Ocean: the first is Mauritian author Ananda Devi's novella La vie de Joséphin le fou (2003), and the second is Comoran author Ali Zamir's novel Anguille sous roche (2016). Through detailed literary analysis, this article demonstrates that in both prose narratives, the perspectives of marine creatures are crucial to the complete telling of intergenerational violence: in particular, the seemingly “infinite” memory and determination of eels becomes an antidote to the fragmentation caused by human trauma. Additionally, this article argues that in both texts, the anguilliform is not simply a theme but also a method, which allows for novel archipelagic forms of storytelling and memory that are as slippery and sinuous as the animals who inspire it. The eel's anguilliform movement thus becomes a source of stylistic and narrative renewal, which allows both texts to embody commentary on the ethical slipperiness of their narratives, as well as on readers’ positionality and complicity.

Untangling the Magelonidae (Annelida: Polychaeta) of southern Africa, including the description of a new species

‘A monograph on the Polychaeta of Southern Africa’ by J. H. Day, published in 1967 and covering over 700 species, was considered an essential reference text for marine biologists. Nonetheless, despite the major contribution it has made, we now know that the biodiversity of Polychaeta (commonly known as bristleworms) in southern Africa has been underestimated by more than 500 species. As one of the top 20 polychaete families highlighted as requiring revision in southern Africa, direct observation of magelonids in the collections of Iziko Museums of South Africa and Natural History Museum, London identified by John Day, and additional material has been carried out. This has revealed that the original description of Magelona capensis was based on two species. Consequently, an additional redescription of the holotype of M. capensis is provided herein, and the additional material is described as Magelona ekapa sp. nov. The new species shares similarities with eight species comprising the ‘Magelona pitelkai group’, which is further discussed. A redescription of M. cincta is also provided based on the holotype and freshly collected material. A specimen from Morrumbene Estuary, southern Mozambique, originally identified as M. cincta likely represents an undescribed species: images and a description are provided here, but the species will remain undescribed until further material becomes available. A dichotomous indentification key and a table of characters is provided for all known southern African species of the Magelonidae.

Species-specific eDNA assay development for enhanced box jellyfish risk management in coastal environments

Human interaction with marine creatures holds both positive and negative dimensions. Coastal communities benefit from marine environments, relying on them for sustenance and livelihoods. Fishing activities support economies, and marine biodiversity contributes to overall ecosystem health. However, challenges like overfishing, habitat destruction, and pollution pose threats to both marine life and human communities. Recently, there has been widespread concern regarding the potential increase in jellyfish populations across global marine ecosystems, attributed mainly to environmental factors such as climate drivers and anthropogenic forces, or their complex interactions. Encounters with hazardous marine species, such as box jellyfish, exemplify the dangers associated with coastal activities. Unintended interactions may lead to stings, injuries, and even fatalities, necessitating proactive measures and advanced technologies. This study addresses the inadequacies of existing measures in preventing box jellyfish incidents by introducing environmental DNA (eDNA) assays for detecting the deadly Chiropsoides buitendijki and focuses on developing qPCR and dPCR-based eDNA assays. Emphasising prevention over treatment, the study establishes a proactive system to assess C. buitendijki distribution across 63 tourist beaches in the Gulf of Thailand. Comparative analysis highlights the superior performance of dPCR over qPCR and traditional surveys. The dPCR experiment yielded positive results for all eDNA samples collected at sites where C. buitendijki had previously been identified. Remarkably, the eDNA testing also detected positive results in 16 additional sample locations where no physical specimens were collected, despite reported jellyfish stings at some of these sites. These findings underscore the precision and efficacy of the proposed eDNA detection technology in the early detection and assessment of box jellyfish distribution. This advancement therefore not only aids ecological research but also serves as a valuable tool for safeguarding public health, providing an early warning system for potential jellyfish encounters. Balancing positive human-marine interactions with effective risk mitigation strategies is crucial for sustainable coexistence, the preservation of marine ecosystems, and human well-being.

Classification of eco-zones from the factors and processes controlling phytoplankton biomass

Phytoplankton is of utmost importance to the marine ecosystem and, subsequently, to the Blue Economy. This study aims to explain the reasons for variability of phytoplankton by estimating the dependency of Chlorophyll-a (Chl-a) on various limiting factors using statistics. The global oceans are classified into coherent units that display similar sensitivity to changing parameters and processes using the k-means algorithm. The resulting six clusters are based on the limiting factors (PAR, iron, or nitrate) that modulate Chl-a yield divisions of the oceans, similar to regions of different trophic statuses. The clusters range from the polar and equatorial regions with high nutrient values limited by light, to open oceanic regions in downwelling gyres limited by nutrients. Some clusters also show a high dependency on marine dissolved iron. Further, oceans are also divided into eight clusters based on the processes (stratification, upwelling, topography, and solar insolation) that impact ocean productivity. The study shows that considering temporal variations is crucial for segregating oceans into ecological zones by utilizing correlation of time-series data into classification. Our results provide valuable insights into the regulation of phytoplankton abundance and its variability, which can help in understanding the implications of climate change and other anthropogenic effects on marine biology.

Use of Unmanned Surface Vehicles (USVs) in Water Chemistry Studies.

Unmanned surface vehicles (USVs) equipped with integrated sensors are a tool valuable to several monitoring strategies, offering enhanced temporal and spatial coverage over specific timeframes, allowing for targeted examination of sites or events of interest. The elaboration of environmental monitoring programs has relied so far on periodic spot sampling at specific locations, followed by laboratory analysis, aiming at the evaluation of water quality at a catchment scale. For this purpose, automatic telemetric stations for specific parameters have been installed by the Institute of Marine Biological Resources and Inland Waters of Hellenic Centre for Marine Research (IMBRIW-HCMR) within several Greek rivers and lakes, providing continuous and temporal monitoring possibilities. In the present work, USVs were deployed by the Athens Water and Sewerage Company (EYDAP) as a cost-effective tool for the environmental monitoring of surface water bodies of interest, with emphasis on the spatial fluctuations of chlorophyll α, electrical conductivity, dissolved oxygen and pH, observed in Koumoundourou Lake and the rivers Acheloos, Asopos and Kifissos. The effectiveness of an innovative heavy metal (HM) system installed in the USV for the in situ measurements of copper and lead was also evaluated herewith. The results obtained demonstrate the advantages of USVs, setting the base for their application in real-time monitoring of chemical parameters including metals. Simultaneously, the requirements for accuracy and sensitivity improvement of HM sensors were noted, in order to permit full exploitation of USVs' capacities.

Assessment of Cow Urine as a Nutrient Medium for Indoor Cultivation of Spirulina sp.

This study aims to explore the feasibility of utilizing cow urine as an economical alternative nutrient source for microalgae cultivation. By leveraging its mineral content and cost-effectiveness, this research investigates the potential to reduce production expenses associated with nutrient mediums, thus enhancing the value proposition of microalgae-derived products on a commercial scale. In order to assess its efficacy, cow urine was gathered, diluted, and introduced into our Spirulina-modified medium. This concoction was subjected to 8 hours of daily light exposure. Following an 18-day incubation period, we analysed the biomass quantity, specific growth rate, density, chlorophyll level, and total carotenoid content. In the Aquatic Biology laboratory at VNSGU, an experiment was conducted utilizing five distinct concentrations (0.2 ml, 1 ml, 2 ml, 3 ml, and 4 ml in 200 ml) over an 18-day period. The control flask (0 ml) did not contain cow urine. In our current investigation, Spirulina cultivated in a cow urine extract at a concentration of 0.2 ml/200 ml exhibited a dry weight of 0.034±0.0029 g, a specific growth rate of 0.0016±0.00015, and a carotenoid content of 4.683±0.015. The density of Spirulina peaked at 0.0052±0.00005 with a concentration of 1 ml/200 ml of cow urine extract. Across various concentrations of cow urine extract, including 2 ml/200 ml (8.022±0.016 mg/L), 0.2 ml/200 ml (2.191±0.021 mg/L), and 4 ml/200 ml (0.631±0.020 mg/L), Spirulina exhibited higher levels of chlorophyll a, b, and c compared to the control medium in indoor culture setups.

Multi-model of ammonia nitrogen in aquaculture water based on EM algorithm1

The factors of water quality in the intensive marine stichopus japonicus aquaculture process are changing with seasons, so water temperature, salinity, pH value and nitrite were selected as auxiliary variables to measure the concentration of ammonia nitrogen. FCM (Fuzzy C-means) algorithm was adopted to classify them. Based on the EM (Expectation Maximization) algorithm, fuzzy sub-models of ammonia nitrogen concentration were constructed around each operating point, and finally the fuzzy sub-models were combined according to the posterior distribution of the characteristics of the sampling data. Based on the data collected at Xinyulong Marine Biological Seed Technology Co., Ltd, in Dalian China, the ammonia nitrogen concentration prediction model was tested and verified.

Underwater Imagery Enhancement with Multi-Channel Histogram Equalization, Depth-Adaptive Correction, and Deep Reinforcement Learning

Underwater imagery plays a pivotal role in various scientific, industrial, and recreational applications, ranging from marine biology and oceanography to underwater archaeology and resource exploration. However, capturing high-quality images in underwater environments poses unique challenges due to factors such as light attenuation, color distortion, and particulate matter suspended in the water. In recent years, significant advancements have been made in the development of advanced techniques for enhancing underwater imagery aimed at improving perceptual quality, sharpness, and detail preservation. This research explores state-of-the-art enhancement techniques, focusing on multi-channel histogram equalization and depth-adaptive correction in the context of deep reinforcement learning (DRL) and variational autoencoders (VAE). The research presents a comprehensive analysis of the performance of these techniques using numerical metrics such as perceptual quality, sharpness, and detail preservation, derived from experimental evaluations. The findings demonstrate the effectiveness of VAE in enhancing perceptual quality and sharpness, with underwater image dehazing exhibiting commendable results as well. Furthermore, Convolutional Neural Networks (CNN) emerge as a promising approach for detail preservation in underwater images. By advancing the capabilities of underwater image enhancement techniques, this research contributes to the broader goal of unlocking the full potential of underwater exploration and understanding. The findings reveal significant improvements in image quality achieved by these techniques. VAE exhibits the highest perceptual quality scores, averaging around 0.84, with sharpness scores reaching approximately 0.91.