Jellyfish Blooms Research Articles

Seasonal and long-term variations of nutrients in Liaodong Bay, China: Influencing factors and ecological effects

Nutrients are essential for marine primary productivity and have a critical role in maintaining the structure and function of marginal. Variations in nutrient levels in sea ecosystems can influence ecological disturbances significantly. The Liaodong Bay (LDB) is a semi-enclosed marginal sea in northern China. It has experienced severe eutrophication since the 1990s, leading to considerable environmental challenges. Understanding of seasonal and long-term nutrient dynamics in the LDB is limited. We examined seasonal datasets collected in May (spring), August (summer), November (autumn), and March (winter) of 2019, and analyzed long-term trends through historical records spanning multiple decades. Nutrients accumulated during autumn/winter but were depleted during spring/summer. A low concentration of dissolved inorganic phosphate led to an increased nitrogen ratio exceeding the Redfield ratio (>16) during winter, spring, and summer, driven by phytoplankton growth. In late-autumn, nutrient concentrations increased, with ratios approaching the Redfield ratio. Phosphorus limitation prevailed in spring, summer, and winter, while silicon limitation dominated in autumn. Dissolved inorganic nitrogen and nitrogen ratios in the LDB increased sharply since the 1980s, peaking before declining after 2013. Dissolved silica and silicon ratios decreased steadily, stabilizing in recent years. These trends imply a shift from nitrogen-to-phosphorus limitation, influenced by riverine inputs and atmospheric deposition. These nutrient fluctuations may have significant ecological effects, including dinoflagellate abundance, algal blooms, and jellyfish blooms. Our analyses highlight the complexity of nutrient dynamics and positive impact of local nutrient-reduction policies implemented in recent years in improving the environmental quality of the LDB.

Homosalate and ERK Knockdown in the Modulation of Aurelia coerulea Metamorphosis by Regulating the PI3K Pathway and ERK Pathway.

Metamorphosis control is pivotal in preventing the outbreak of jellyfish, and it is often studied using common model organisms. The widespread use of the ultraviolet blocking agent homosalate in cosmetics poses a threat to marine ecosystems. Although the impact of homosalate on marine organisms has been extensively examined, there is a notable absence of research on its effects on jellyfish metamorphosis and the underlying mechanisms, warranting further investigation. In this study, we first established a study model by using 5-methoxy-2-methylindole to induce Aurelia coerulea metamorphosis, and selected homosalate as a PI3K agonist and an ERK agonist, while we used YS-49 as a specific PI3K agonist, as well as ERK knockdown, to observe their effect on the metamorphosis of Aurelia coerulea. The results showed that an Aurelia coerulea metamorphosis model was established successfully, and the PI3K agonist homosalate, YS-49, and the knockdown of ERK molecules could significantly delay the metamorphosis development of Aurelia coerulea. We propose that activating PI3K/Akt and inhibiting the ERK pathway are involved in the delayed development of Aurelia coerulea, which provides a new strategy for the prevention and control of jellyfish blooms.

Key environmental parameters and numerical prediction model of jellyfish bloom in Qingchuan Bay Nuclear Power Plant, China

In recent years, there has been a notable increase in cooling water intake blockage caused by marine organism blooms at coastal nuclear power plants worldwide, resulting in shutdowns of nuclear power plants and large economic losses. A sizable portion of these incidents were caused by blooms from jellyfish, a planktonic invertebrate with a unique growth pattern. Suitable external conditions are conducive to the rapid growth of jellyfish, and blooms can occur within a few days. In order to better predict jellyfish bloom and enable nuclear power plants to prepare for it in advance, this study explores the numerical relationship between jellyfish biomass and environmental parameters. A series of time windows (evaluation intervals) were defined and constructed by a time-series recursive approach, which solved the problem of poor correlation between jellyfish biomass and environmental parameters at non-bloom points. The optimal time window length D = 10 was obtained, and the key environmental parameters affecting jellyfish biomass were screened as sea surface temperature, salinity, voltage value, dissolved oxygen, and chlorophyll. According to the ADF and KPSS tests, the key parameters have no significant time dependence, which ensures the stability and reliability of the subsequent predictions. The jellyfish bloom prediction model was derived by calculating the score F through the recursive Principal Component Analysis of the key environmental parameter in the time interval preceding the prediction point. The sudden change moments of score F correspond well to the jellyfish bloom moments, and the sudden change moments are all advanced for a period of time compared to the bloom time, which can provide valuable time for the nuclear power plant to organize manpower to deal with the blockage. Finally, a maximum score F threshold model was proposed to be coupled with the jellyfish bloom prediction model to provide a more robust basis for early warning of jellyfish at nuclear power plants.

Bycatch discard patterns in a tropical beach seine fishery across different monsoonal periods

ABSTRACT The beach seine fishery at Oruwella, Tangalle, Sri Lanka (6°1'51“N; 80°ˊ47'57”E) was studied for its discarded bycatch over 34 months. Fishes of the benthic family-Cynoglossidae were most frequent (40.5 %) for the whole study period while jellyfish (Aurelia sp) showed the highest catch frequency (77.2 %) during the southwest monsoon. The species composition of the bycatch (per haul) was higher during the northeast monsoon than the other two periods. Thus, monsoonal and incidental jellyfish (Aurelia sp) blooms had significant impacts on the abundance and species composition of the bycatch. The study reported 26 bycatch species where 65 % and 73% of the bycatch organism types were benthic and non-commercial species respectively. As 72.6 % of hauls had less than 20 bycatch individuals, the total bycatch abundance (per haul) was comparatively low. The study also revealed the lowest number of discarding bycatch species among other studies. Cod-end made with relatively large (>0.5cm) mesh and traditional knowledge of fishers to forecast specific commercial fish schools contributed to lowering the abundance and the bycatch species in this fishery. As alive bycatch is thrown back into the beach water, the chances of survival are likely to be increased for some bycatch individuals.

From ctenophores to scyphozoans: parasitic spillover of a burrowing sea anemone

Most host-parasite associations are explained by phylogenetically conservative capabilities for host utilization, and therefore parasite switches between distantly related hosts are rare. Here we report the first evidence of a parasitic spillover of the burrowing sea anemone Edwardsiella carnea from the invasive ctenophore Mnemiopsis leidyi to two scyphozoan hosts: the native Mediterranean barrel jellyfish Rhizostoma pulmo and the invasive Indo-Pacific nomad jellyfish Rhopilema nomadica, collected from the Eastern Mediterranean Sea. Edwardsiella carnea planulae found in these jellyfish were identified using molecular analyses of the mitochondrial 16S and nuclear 18S rRNA genes. Overall, 93 planulae were found on tentacles, oral arms, and inside of the gastrovascular canals of the scyphomedusae, whereas no infection was observed in co-occurring ctenophores. DNA metabarcoding approach indicated seasonal presence of Edwardsiella sp. in the Eastern Mediterranean mesozooplankton, coinciding with jellyfish blooms in the region. Our findings suggest a non-specific parasitic relationship between Edwardsiella carnea and various gelatinous hosts based on shared functionality rather than evolutionary history, potentially driven by shifts in host availability due to jellyfish blooms. This spillover raises questions about the ecological impacts of parasitism on native and invasive scyphozoan hosts and the potential role of Edwardsiella in controlling their populations.

The Chinese Freshwater Jellyfish Unbound

Jellyfish are commonly known as dangerous sea creatures that humans should avoid. Focusing on the newly discovered freshwater jellyfish in the late nineteenth century, this article explores a global history of Craspedacusta sowerbii, a species native to China first noted in nineteenth-century Britain but since traveling the world over. The worldwide distribution of C. sowerbii, as both polyps and medusae, made it a global subject of scientific inquiry. However, no independent study has examined the history behind the origin, circulation, and implication of the freshwater jellyfish and its relationship with marine types. The late nineteenth century was the period when our premodern knowledge of jellyfish transformed from it being purely a marine life to the modern recognition of jellyfish as both marine and freshwater organisms, triggered by the discovery and discussion of the Chinese freshwater jellyfish C. sowerbii among naturalists and philosophers. This article focuses on Arthur de Carle Sowerby’s engagement with C. sowerbii in terms of narratives of evolution, nomenclature, and bioinvasion between 1880 and 1941. I argue that jellyfish, as a lowly form of invertebrates, should be taken more seriously by historians of modern China and historians of biology who are interested in the diverse roles of animals in shaping human–animal interactions in the Anthropocene. While the scientific research of jellyfish’s global bloom abounds, the interpretation of the global rise of jellyfish could benefit from a historically and culturally bound analysis of this classical animal. This is particularly so as scientists recognized the diverse perceptions of jellyfish. The global jellyfish bloom requires historical perspectives on a topic that has hitherto received scant attention from historians of science.

Using artificial neural networks and citizen science data to assess jellyfish presence along coastal areas

Abstract Jellyfish blooms along coastal areas can pose significant challenges for beach users and local authorities. Understanding the factors influencing jellyfish presence is crucial for effective management and mitigation strategies. In this study, citizen science data from the Andalusian coast (232 beaches, in 40 different localities) and machine learning techniques are used to investigate if the presence and absence of jellyfish along coastal areas can be predicted. A multi‐layer perceptron (MLP) neural network was employed to classify user comments regarding jellyfish presence or absence, achieving an accuracy of approximately 96%. The MLP model demonstrated robustness in handling non‐linear classification problems and noise, although it showed lower precision for predicting jellyfish presence, likely due to an imbalance in the dataset. Environmental data were also incorporated to characterise the influence of sea surface temperature, wind direction and wind speed on jellyfish distribution. The results align with previous studies, suggesting these environmental factors significantly impact jellyfish presence. Synthesis and applications. This research provides actionable recommendations for beach management. The implementation of continuous monitoring of sea surface temperature and wind conditions will enable more accurate predictions of jellyfish distribution. Adaptive management strategies that respond dynamically to environmental data will help mitigate the impact of jellyfish blooms on coastal tourism and public health.

Dynamic population modeling of bacterioplankton community response to gelatinous marine zooplankton bloom collapse and its impact on marine nutrient balance

The diverse microbial community in the ocean, encompassing various metabolic types, interacts with the wide array of compounds in the dissolved organic matter (DOM) pool, thereby influencing the ocean’s biogeochemical state and, consequently, the global climate. Our understanding of the interactions between specific DOM constituents and microbial consortia remains limited, necessitating further refinement to achieve a mechanistic comprehension of the relationship between the DOM field and the microbial metabolic network. Attaining this level of understanding is crucial for accurately predicting the marine ecosystem’s response to natural and anthropogenic perturbations. To address this gap, we developed a bacterial population model based on the von Foerster equation. This model aims to describe the complex microbial-mediated degradation of gelatinous zooplankton (hereinafter ‘jellyfish’) detritus, as an important, but largely overlooked source of DOM in the ocean. By considering microbial growth and decay, as well as DOM uptake, and nutrient release, the model is able to describe the microbial community’s life cycle, and the biochemical transformations of the jellyfish-derived organic matter. We fitted the model to results of laboratory microcosm experiments conducted to simulate scenarios experienced by ambient microbiomes during decay of two different jellyfish species in the northern Adriatic Sea. By interpreting the fitted parameters, we highlight the differences in the microbial response to different jellyfish species, namely how these affect the microbial community composition and the release of nutrients. This model has been specifically designed for integration with ocean circulation models to create a comprehensive physical-biogeochemical ocean model. Such an extended model can be utilized for multi-scale simulations to assess the system’s response to jellyfish and jellyfish-derived organic matter. Given that jellyfish blooms may become more prevalent under future ocean scenarios, this modeling approach is essential for understanding their potential impact on marine ecosystems.

Trophic effects of jellyfish blooms on fish populations in ecosystems of the coastal waters of China

Jellyfish play an important role in the material cycling and energy flow of food webs, and massive aggregations may have deleterious consequences for local fisheries; yet a theoretical framework of the trophic effects of jellyfish blooms on coastal fisheries is unclear. To address this knowledge gap, we assessed the trophic interactions between cooccurring bloom jellyfish and dominant fish groups (omnivorous fish and piscivorous fish) in the coastal waters of China (CWC) via stable isotope analysis; we subsequently discussed how jellyfish blooms may affect energy flow through coastal ecosystems. Our results indicate a considerable degree of trophic overlap (mean ratio > 65 %) between jellyfish and small omnivorous fish (< 10 cm), highlighting a similarity in feeding habits, while the overlap ratio decreased to <55 % of the large omnivorous fish group (> 10 cm). Relatively higher trophic levels and smaller overlaps of large omnivorous fish were found in the ecosystem with high jellyfish biomass, which suggested that they may reinforce the ontogenetic trophic shift pattern to alleviate the potential for resource competition with jellyfish under conditions of jellyfish explosion. The smallest trophic overlap (< 20 %) highlighted the strong trophic differentiation between jellyfish and piscivorous fish. Additionally, our study suggested that a massive aggregation of jellyfish can negatively influence zooplankton but may not transfer energy further up efficiently, implying a weak trophic coupling between jellyfish and upper-trophic levels in CWC ecosystems. Thus, we speculate that jellyfish play an important role in shaping pathways involved in the energy transfer of food webs and that large blooms may negatively affect fisheries through bottom-up control affecting prey availability. In general, these results hold strong potential to further improve the understanding of the trophic interactions between jellyfish and fish populations. Furthermore, this study provides valuable data for predicting the consequences of jellyfish blooms on ecosystems, and is crucial for ecosystem-based management of coastal fisheries.

Swimming ability of the Carybdea marsupialis (Cnidaria: Cubozoa: Carybdeidae): implications for its spatial distribution

AbstractAlthough usually considered part of the plankton, cubozoans are strong swimmers. The aim of this study was to determine the influence of the active swimming ability of the box jellyfish Carybdea marsupialis on the spatial distribution of a well‐studied population in the NW Mediterranean where adults and juveniles do not overlap geographically. To accomplish this, we analyzed the swimming speed, effective velocity, effective displacement index (EDI), and proficiency of 27 individuals with diagonal bell widths (DBWs) ranging from 1.1 to 36 mm. The laboratory analysis utilized conventional video recordings and the video analysis tool Tracker. Mean swimming speed for small juveniles, medium juveniles and adults was 9.7 ± 0.8, 21.9 ± 2.3 and 43.1 ± 1.8 mm s−1 (mean ± se), respectively. Effective velocity was also proportional to size, ranging from 5.0 ± 0.7 to 38.8 ± 3.1 mm s−1 (mean ± se). The calculated EDI for each group was 0.51 ± 0.05, 0.84 ± 0.06 and 0.90 ± 0.05 (mean ± se), respectively. Proficiency showed an inverse trend, from 6.4 ± 0.6 s−1 for the small juveniles to 1.36 ± 0.05 for adults (mean ± se). Comparing the swimming speed results with the local currents obtained from drifting buoys analyzed in the area, adults would be able to swim strongly enough to overcome almost 70% of the currents, whereas the small juveniles would not reach 17%. This would allow larger individuals to select their habitat, while smaller individuals are left dependent on advection. Although experiments adding currents in aquaria would be necessary to confirm these theoretical results, the data obtained would be useful in improving the performance of bio‐mathematical models used to predict jellyfish blooms since, even though the sting of C. marsupialis is non‐fatal, it may produce systemic effects in sensitive swimmers.

Blooms of the dragon thimble jellyfish, Linuche draco, sometimes co-occur with marine heatwaves

Blooms of the dragon thimble jellyfish, Linuche draco, sometimes co-occur with marine heatwaves

Ghosts of the Techno-Fix Ocean? A Short History of Periphylla periphylla in the Norwegian Fjords

Ghosts of the Techno-Fix Ocean? A Short History of Periphylla periphylla in the Norwegian Fjords

The unpredictability of scyphozoan jellyfish blooms

The study of jellyfish blooms has gained attention in the recent decades because of the importance of forecasting and anticipating them and avoiding their interference with human activities. However, after thirty years of scientific effort (monitoring systems, empirical laboratory and field studies, modeling, etc.), the occurrence of blooms remains unpredictable, and their consequences unavoidable. Climate change, eutrophication, overfishing, coastal construction, and species translocation have been suggested as stressors that increase them, but robust evidence to support these claims is limited. The widespread belief that jellyfish blooms are “increasing in number” has been challenged in recent years. Among the gelatinous zooplankton, the bloom forming species are concentrated in the class Scyphozoa, and the number of species with at least one recorded bloom has increased during the last decade. The analyses of long-term time series show seasonality in the dynamic of each blooming jellyfish species population, but the blooms vary in intensity and there are years of an unexplained absence of jellyfish. In this review, we focus on the current state of knowledge, uncertainties and gaps in the critical points that can strongly influence the intensity of the bloom or even lead to the absence of the medusa population. These points include ephyrae, planulae and scyphistoma natural, predatory or fishing mortality, the molecular pathway of strobilation, benthic population dynamics, planula settlement and ephyra to medusa transition success. Some of these points account for certain empirical laboratory evidence under controlled conditions, and are difficult to be studied on the field, but the different sources of non-typically recorded variability need to be addressed to improve our understanding of jellyfish population dynamics.

Bacterial degradation of ctenophore Mnemiopsis leidyi organic matter.

Blooms of gelatinous zooplankton, an important source of protein-rich biomass in coastal waters, often collapse rapidly, releasing large amounts of labile detrital organic matter (OM) into the surrounding water. Although these blooms have the potential to cause major perturbations in the marine ecosystem, their effects on the microbial community and hence on the biogeochemical cycles have yet to be elucidated. We conducted microcosm experiments simulating the scenario experienced by coastal bacterial communities after the decay of a ctenophore (Mnemiopsis leidyi) bloom in the northern Adriatic Sea. Within 24 h, a rapid response of bacterial communities to the M. leidyi OM was observed, characterized by elevated bacterial biomass production and respiration rates. However, compared to our previous microcosm study of jellyfish (Aurelia aurita s.l.), M. leidyi OM degradation was characterized by significantly lower bacterial growth efficiency, meaning that the carbon stored in the OM was mostly respired. Combined metagenomic and metaproteomic analysis indicated that the degradation activity was mainly performed by Pseudoalteromonas, producing a large amount of proteolytic extracellular enzymes and exhibiting high metabolic activity. Interestingly, the reconstructed metagenome-assembled genome (MAG) of Pseudoalteromonas phenolica was almost identical (average nucleotide identity >99%) to the MAG previously reconstructed in our A. aurita microcosm study, despite the fundamental genetic and biochemical differences of the two gelatinous zooplankton species. Taken together, our data suggest that blooms of different gelatinous zooplankton are likely triggering a consistent response from natural bacterial communities, with specific bacterial lineages driving the remineralization of the gelatinous OM.IMPORTANCEJellyfish blooms are increasingly becoming a recurring seasonal event in marine ecosystems, characterized by a rapid build-up of gelatinous biomass that collapses rapidly. Although these blooms have the potential to cause major perturbations, their impact on marine microbial communities is largely unknown. We conducted an incubation experiment simulating a bloom of the ctenophore Mnemiopsis leidyi in the Northern Adriatic, where we investigated the bacterial response to the gelatinous biomass. We found that the bacterial communities actively degraded the gelatinous organic matter, and overall showed a striking similarity to the dynamics previously observed after a simulated bloom of the jellyfish Aurelia aurita s.l. In both cases, we found that a single bacterial species, Pseudoalteromonas phenolica, was responsible for most of the degradation activity. This suggests that blooms of different jellyfish are likely to trigger a consistent response from natural bacterial communities, with specific bacterial species driving the remineralization of gelatinous biomass.

Jellyfish bloom: Abundance, distribution and impact analysis in the commercial dol net fishing ground of Northwest coast of India, Arabian Sea

Jellyfish bloom: Abundance, distribution and impact analysis in the commercial dol net fishing ground of Northwest coast of India, Arabian Sea

Molecular and cellular basis of life cycle transition provides new insights into ecological adaptation in jellyfish

&lt;p&gt;Jellyfish are renowned for their complex life cycles and important ecological and evolutionary position. The unique transition from the sessile polyp to motile medusa stages is a key process determining a switch in jellyfish behaviour and regulating the formation of jellyfish blooms. Here, we presented a comprehensive cell atlas spanning four successive life cycle stages during the polyp-to-medusa transition in the scyphozoan jellyfish &lt;i&gt;Aurelia&lt;/i&gt; &lt;i&gt;coerulea&lt;/i&gt;. Moreover, we characterised the variation in cell composition and gene expression patterns during the phase transition, especially in the neuromuscular system. We found several previously unreported cell types that potentially underpin the complex swimming behaviour of jellyfish. Furthermore, we discovered the pivotal role of &lt;i&gt;HOX1&lt;/i&gt; in modulating the genesis of striated muscles in &lt;i&gt;A&lt;/i&gt;. &lt;i&gt;coerulea&lt;/i&gt;. Collectively, this study provides valuable insights into the cellular and molecular mechanisms underlying the complex life cycle transition and helps to advance our understanding of ecological adaptation in jellyfish.&lt;/p&gt;

Microbiota regulates life-cycle transition and nematocyte dynamics in jellyfish

Jellyfish represent one of the most basal animal groups with complex life cycles. The polyp-to-medusa transition, termed strobilation, is the pivotal process that determines the switch in swimming behavior and jellyfish blooms. Their microbiota plays an essential role in strobilation. Here, we investigated microbiota-mediated host phenotype dynamics during strobilation in the jellyfish Aurelia coerulea via antibiotic-induced microbiome alteration. Microbial depletion delayed the initiation of strobilation and resulted in fewer segments and ephyrae, which could be restored via microbial recolonization. Jellyfish-associated cyanobacteria, which were eliminated by antibiotics in the polyp stage, had the potential to supply retinal and trigger the retinoic acid signaling cascade, which drove the strobilation process. The microbiota regulated nematocyte development and differentiation, influencing the feeding and growth of the jellyfish. The findings improve our understanding of jellyfish-microbe interactions and provide new insights into the role of the microbiota in shaping feeding behavior through nematocyte dynamics.

Acoustic Target Strength of Jellyfish, Nemopilema nomurai, Measured at Multi-Frequency and Multi-Orientation

The jellyfish Nemopilema nomurai occupies an important position in the Northwest Pacific ecosystem, and monitoring its biomass is necessary to ensure the protection of fishery resources and the safety of offshore industrial production. The acoustic method has been proposed for jellyfish flux estimation and bloom warning, in which the target strength (TS) of the jellyfish is a crucial parameter. However, varied swimming orientations of jellyfish aggregation result in different backscatter strengths. The acoustic echo characteristics in horizontal swimming orientations and multi-frequency broadband signals are yet to be revealed. This study aims to obtain the TS of jellyfish in various orientations and to comprehensively investigate the jellyfish acoustic echo features at various frequency broadband sounds. In an anechoic tank, we used wide-band echosounder and 70 kHz, 120 kHz, and 200 kHz split-beam transducers to measure the TS of jellyfish swimming omnidirectionally. The results show a difference of approximately 4 dB in the jellyfish’s normalized TS at 70 kHz (frequency range: 45 kHz to 95 kHz) and 200 kHz (frequency range: 160 kHz to 260 kHz) center frequency. The normalized TS of jellyfish varies by around 8 dB between horizontal and vertical swimming orientations. For jellyfish swimming horizontally, the TS and bell diameter have the following least squares fits: T S D 70 k H z = 20 log D − 89.36 r 2 = 0.83 ; T S D 200 k H z = 20 log D − 93.85 r 2 = 0.83 . The swimming orientation has significant effects on TS estimation and model construction.

Nutritional composition assessment and antimicrobial activity of Catostylus perezi, jellyfish blooms along the coast of Pakistan: an awareness to avoid food neophobia in Pakistan

This study highlighted the nutritional importance of Catostylus perezi (an edible jellyfish) in Pakistan; a society where a large proportion of the population suffers from malnutrition, while C. perezi, a blessing of the sea, is wasted or exported. In the present study, the amino acid and fatty acid profiles of the oral arms and umbrella of C. perezi were determined by HPLC. The total amino acid concentration (ΣAA) in the oral arms was 151.19 mg/100g, while in the umbrella it was 100.17 mg/100g. The ratio of total essential amino acids to total non-essential amino acids (TEAA/TNEAA) was 0.72 in the oral arms, while it was 0.70 in the umbrella. Higher amount of ω-3 with lower ratio of ω-6/ω-3 in oral arms (0.52), rather umbrella (ω-6/ω-3 ratio; 0.62). The antimicrobial activity, MIC, MBC, and MFC of the whole body of the edible jellyfish were determined. On the basis of polarity, different solvents were used, e.g. water, methanol, dichloromethane, chloroform, and n-hexane. Among all the extracts, the water extract gave the highest ZOI against C. xerosis (29 mm), while the n-hexane extract gave the lowest ZOI against S. aureus (MRSA) ATCC 33591 (8.20 mm). The water extract of C. perezi had high potential against C. xerosis with the highest AMI and PAI (1.53 and 153, respectively), while the same extract had the highest TAI against E. coli (81.43 mL/g). For fungi/yeast, the methanolic extract had the highest ZOI (29.70 mm) against S. cerevisiae and the lowest MIC/MFC (2.40 µg/mL) against the same pathogen. The n-Hexane extract gave the lowest ZOI (11.10 mm) against P. variotii and the highest MIC/MFC (31.60 µg/mL) against Penicillium sp. Atomic force microscopy (AFM) was used to analyse the disintegrating effect of the extracts (with the highest antimicrobial effect) on the cells of selected Gram-positive, Gram-negative and yeast species. The amino acid and fatty acid profiles and antimicrobial assessment showed that C. perezi has great nutritional importance, so the use of C. perezi as food is highly recommended for the Pakistani community.

Real-time jellyfish classification and detection algorithm based on improved YOLOv4-tiny and improved underwater image enhancement algorithm

The outbreak of jellyfish blooms poses a serious threat to human life and marine ecology. Therefore, jellyfish detection techniques have earned great interest. This paper investigates the jellyfish detection and classification algorithm based on optical images and deep learning theory. Firstly, we create a dataset comprising 11,926 images. A MSRCR underwater image enhancement algorithm with fusion is proposed. Finally, an improved YOLOv4-tiny algorithm is proposed by incorporating a CBMA module and optimizing the training method. The results demonstrate that the detection accuracy of the improved algorithm can reach 95.01%, the detection speed is 223FPS, both of which are better than the compared algorithms such as YOLOV4. In summary, our method can accurately and quickly detect jellyfish. The research in this paper lays the foundation for the development of an underwater jellyfish real-time monitoring system.