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The impact of climate change on fish distribution has drawn increasing attention worldwide. Studying the distribution patterns and habitat evolution trends of largehead hairtail (Trichiurus japonicus), an important fishery resource in the northern South China Sea (NSCS), is of great significance for the management and sustainable utilization of fishery resources. This study uses an ensemble species distribution model to analyze the seasonal distribution patterns of T. japonicus in the NSCS and predict the changes in highly suitable habitats of T. japonicus under four future climate scenarios (IPCC Shared Socioeconomic Pathways SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). The results show that the area of suitable habitats in the Beibu Gulf is expected to increase, while that in the offshore of Guangdong will significantly decrease. In different seasons, there are differences in environmental factors affecting the distribution of T. japonicus, among which sea bottom temperature (SBT) and bathymetry (BM) are key factors. Under the SSP1-2.6 scenario, the area of highly suitable habitats for T. japonicus is expected to decrease by 30.54% by the 2100s, while under the SSP5-8.5 scenario, it is expected to decrease by 53.67%. Our research results show that the active range of T. japonicus in the NSCS has different adaptive responses to different climate change scenarios, which has an important impact on the development and management of T. japonicus resources. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? The commercial small pelagic fishes (Decapterus maruadsi and Trachurus japonicus) in the Beibu Gulf were still miniaturizing. Fisheries management, characterized by reduced fishing efforts, cannot completely restore population structure in a short period. What are the suggestions for the future fisheries development in the Beibu Gulf? Continuing to maintain low fishing mortality and increasing the catchable length should be the key ways to achieve fishery resource conservation and recovery. Simple Summary: Decapterus maruadsi and Trachurus japonicus, as the main commercial small pelagic fish in the coastal fisheries of China, have been facing the threat of population decline due to overfishing. In this work, we assessed the population status of two commercial small pelagic fish stocks in the Beibu Gulf (in the South China Sea) over the past 15 years (2006–2020). The analysis results show that the commercial small pelagic fishes in the Beibu Gulf were still miniaturizing, and fisheries management characterized by reduced fishing efforts cannot completely restore population structure in a short period. Continuing to maintain low fishing mortality and increasing the catchable length should be the key ways to achieve fishery resource conservation and recovery. Our findings will provide a key scientific basis for future improvements in offshore fisheries management. Long-term variations in population structure, growth, mortality, exploitation rate, and recruitment pattern of two major commercial small pelagic fishes (CSPFs) (Decapterus maruadsi and Trachurus japonicus) are reported based on bottom trawl survey data collected during 2006–2020 in the Beibu Gulf, South China Sea. All individuals collected during each sampling quarter over a period of 15 years were subjected to laboratory-based analysis. In this study, the stock of D. maruadsi and T. japonicus inhabiting the Beibu Gulf was assessed using length-based methods (bootstrapped electronic length frequency analysis (ELEFAN)) to complete stock assessment in different fishery management periods (the division of fisheries management periods was based on China's input and output in the South China Sea offshore fisheries over 15 years, specifically divided into period I (2006–2010), period II (2011–2015), and period III (2016–2020)). The results showed that the mean body length, dominant body size, and estimated asymptotic length of two CSPFs decreased, whereas their growth coefficient decreased, indicating miniaturization and slower growth, respectively. Estimated exploitation rates and catching body length for two CSPFs indicated that both stocks in the Beibu Gulf were overexploited in period I and moderately exploited after 2011. These stocks were taking a good turn in status in period III, with the exploitation rate much lower than the initial period and reversing the downward trend in catching body length. Furthermore, the variations in the spawning season of the two CSPF stocks and their barely satisfactory expected yield indicated the complexity of the current fishery management in the Beibu Gulf. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of those CSPFs in the Beibu Gulf; however, the stock structure already affected by overfishing will be a huge challenge for the conservation and restoration of fisheries resources in the future. Given that the current stocks of D. maruadsi and T. japonicus in the Beibu Gulf still have low first-capture body length (Lc) and high fishing mortality (F) (compared to F0.1), we identify a need to refine population structure by controlling fishing efforts and increasing catchable size, and more consideration should be given to the local fishery resource status in fisheries management. [ABSTRACT FROM AUTHOR]

Chlorella oil nanoliposomes (CO-NLP) were synthesized through ultrasonic injection with ethanol, and their physicochemical properties and hypolipidemic efficacy were systematically investigated. The results revealed that the mean particle size of CO-NLP was 86.90 nm and the encapsulation efficiency (EE) was 92.84%. Storage conditions at 4 °C were conducive to the stability of CO-NLP, maintaining an EE of approximately 90% even after 10 days of storage. The release profile of CO-NLP adhered more closely to the first-order kinetic model during in vitro assessments, exhibiting a slower release rate compared to free microalgae oil. In simulated in vitro digestion experiments, lipolytic reactions of CO-NLP were observed during intestinal digestion subsequent to nanoliposome administration. Notably, the inhibitory effect of CO-NLP on cholesterol esterase activity was measured at 85.42%. Additionally, the average fluorescence intensity of nematodes in the CO-NLP group was 52.17% lower than in the control group at a CO-NLP concentration of 500 μg/mL, which suggests a pronounced lipid-lowering effect of CO-NLP. Therefore, the CO-NLP exhibited characteristics of small and uniform particle size, elevated storage stability, gradual release during intestinal digestion, and a noteworthy hypolipidemic effect. These findings designate CO-NLP as a novel lipid-lowering active product, demonstrating potential for the development of functional foods. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? The abundance of most of fish stocks in the Beibu Gulf continued to decline over the last 15 years. What is the implication of the main finding? Environmental variations caused by climate events can episodically enhance the abundance of certain fish stocks. Warming may be the reason of northward shifts in distribution of most fishes. Improving prediction of ecological responses to climate variability requires understanding how local fish population dynamics are impacted by climate events. The present study was conducted in the Beibu Gulf of the northwestern South China Sea where the fisheries are characterized by high ecological and commercial value. We evaluated the relationship between major commercial fish population dynamics (abundance and distribution) and climate periods, using survey data from 2006–2020. The analysis using random forest and GAM models show that climate events are not the best predictors for the variations of fish abundance, because abundance of most fish stocks decreases significantly with the year, and the increasing fishing pressure over time can better explain the overall downward trend in fishery stocks. However, environmental variables that correlate significantly with interannual variation in ONI may impact fish abundance in short terms. Our research suggests that climate events leading to higher surface seawater salinity in winter favors pelagic fishes by improving habitat availability, and higher near-surface chlorophyll-α concentration during La Niña events provides better food condition for overwintering fish. In addition, there is no clear evidence that climatic events have a significant impact on gravity center of fish distribution, whereas climate change has caused most fishes to move to cooler coastal waters in the north. [ABSTRACT FROM AUTHOR]

To obtain the growth and age characteristics of Diaphus brachycephalus in the South China Sea (SCS), specimens of D. brachycephalus were collected by a mid-water trawl in January and June 2015. The relationship between standard length (L) and body weight (W) was W = 0.00002699L2.8789, with no significant differences between the two survey stations and the sexes. Microscopic observation of the sagittal otoliths revealed that the daily growth increments in each period were divided into the central zone, middle zone, and external zone. The age was determined by summing the daily growth increments of the three areas. The von Bertalanffy growth curve fitted to the relationship between age and L was shown as: L = 65.6[1 − exp{−0.0132(t − 6.94)}], r2 = 0.935. The growth rate decreased from juvenile to adult, with a maximum rate of 0.436 mm day−1. The back-calculated hatching dates of specimens were speculated to be from March to November, but predominantly occurred from April to May and from September to October. [ABSTRACT FROM AUTHOR]

Microalgae is one of the most important components in the aquatic ecosystem, and they are increasingly used in food and medicine production for human consumption due to their rapid growth cycle and survival ability in the harsh environment. Now, the exploration of microalgae has been gradually deepening, mainly focused on the field of nutrition, medicine, and cosmetics. A great deal of studies has shown that microalgae have a variety of functions in regulating the body health and preventing disease, such as nitrogen fixation, antitumor, antivirus, antioxidation, anti‐inflammatory, and antithrombotic. Furthermore, microalgae can synthesize various high‐valued bioactive substances, such as proteins, lipids, polysaccharides, and pigments. In this paper, we have briefly reviewed the research progress of main bioactive components in microalgae, proteins, lipids, polysaccharides, pigments, and other nutrients included, as well as their present application situation. This paper can provide the guidance for research and development of industrial production of microalgae. [ABSTRACT FROM AUTHOR]

Age and growth of a dominant lanternfish Ceratoscopelus warmingii in the South China Sea were investigated based on sagittal otolith microstructure of juvenile and adult specimens collected in June 2015. The length–weight (L-W) relationship for C. warmingii was Wf= 0.00000814 L3.1170 (females) and Wm= 0.00001071 L3.3043 (males), revealing both positive allometric growth and non-significant difference between the sexes. Three distinct zones of the otolith microstructure were depicted, a central zone (CZ), middle zone (MZ) and external zone (EZ). Age was estimated by summing the daily growth increments in otolith sections on the assumption of daily deposition. The von Bertalanffy models of females and males were fitted as Lf = 75.9 [1−exp{−0.0074 (t−14.1)}] and Lm = 65.0[1−exp{−0.0097 (t−7.6)}], respectively. The maximum growth rates estimated were 0.319 mm day−1 for females and 0.345 mm day−1 for males, and thereafter the growth rate decreased with age. The back-calculated hatching date of specimens collected was determined as from August of last year to March of next year with a peak in winter. Theoretical maximum growth of C. warmingii appeared to occur near the metamorphic period. [ABSTRACT FROM AUTHOR]

In the present study, combustion of two seaweeds, Enteromorpha clathrate and Sargassum natans, was carried out in a bench-scale fluidized bed. According to the shrinking core model, combustion of E. clathrate particles resulted in dehydration and release of volatile components first, followed by char combustion. While combustion of S. natans particles resulted in scraps formation due to the rapid release of large amounts of volatiles, followed by expansion and fragmentation. The cross sections of E. clathrate particles and the cokes collected after different combustion durations were analyzed with a scanning electron microscope. Some micro-pores were generated with a rougher surface after being burned for 30 s. When combustion continued for 3 min, a cotton wool-like structure was obtained due to complete release of volatiles. After 4 min of burning, internal surface of the ash particle became cohesive, due to partial melting of ash particles. In addition, the released gases were studied during the combustion process. Results showed that SO2, NOx, and other gases emitted spontaneously as soon as seaweed particles were fed into the fluidized bed, indicating that both pyrolysis and oxidation reactions rapidly take place within the seaweed particles. In general, the heat transfer rate was accelerated by increasing bed temperature and led to an earlier release of volatile components with shortened burnout time. Moreover, increasing air velocity and raising the bed height also enhanced, to some extent, the combustion and shortened the burnout time. [ABSTRACT FROM AUTHOR]

Using the Ecopath with Ecosim software, a trophic structure model of the Beibu Gulf was constructed to explore the energy flows and provide a snapshot of the ecosystem operations. Input data were mainly from the trawl survey data collected from October 1998 to September 1999 and related literatures. The impacts of various fishing pressure on the biomass were examined by simulation at different fishing mortality rates. The model consists of 20 functional groups (boxes), each representing organisms with a similar role in the food web, and only covers the major trophic flows in the Beibu Gulf ecosystem. It was found that the food web of the Beibu Gulf was dominated by the primary producers path, and phytoplankton was the primary producer mostly used as a food source. The fractional trophic levels ranged from 1.0 to 4.02, and the marine mammals occupied the highest trophic level. Using network analysis, the ecosystem network was mapped into a linear food chain, and six discrete trophic levels were found with a mean transfer efficiency of 11.2%. The Finn cycling index was 9.73%. The path length was 1.821. The omnivory index was 0.197. The ecosystem had some degree of instability due to exploitation and other human activities, according to Odum’s theory of ecosystem development. A 10-year simulation was performed for each fishery scenario. The fishing mortality rate was found to have a strong impact on the biomass. By keeping the fishing mortality rate at the current level for all fishing sectors, scenario 1 had a drastic decrease in the large fish groups. The biomass of the small and medium pelagic fish would increase to some extent. The biomass of the small and low trophic level species, jellyfish, prawns and benthic crustaceans would be stable. The total biomass of the fishery resources would have a 10% decrease from the current biomass after 10 years. In contrast, the reduced fishing mortality rate induced the recovery of biomass (scenarios 2–4). In scenario 2, the biomass of the large demersal fish and the large pelagic fish would increase to over 16 times and 10 times, respectively, of their current level. In scenario 4, the biomass of the large pelagic fish would increase to over 3 times of its current level. The total biomass of the fish groups, especially the high trophic level groups, would become significantly higher after 10 years, which illustrates the contribution on biomass recovery by relaxing the fishing pressure. [ABSTRACT FROM AUTHOR]

Carangidae are ecologically and economically important marine fish. The complete mitogenomes of three Carangidae species (Alectis indicus, Decapterus tabl, and Alepes djedaba) were sequenced, characterized, and compared with 29 other species of the family Carangidae in this study. The length of the three mitogenomes ranged from 16,530 to 16,610 bp, and the structures included 2 rRNA genes (12S rRNA and 16S rRNA), 1 control region (a non-coding region), 13 protein-coding genes, and 22 tRNA genes. Among the 22 tRNA genes, only tRNA-Ser (GCT) was not folded into a typical cloverleaf secondary structure and had no recognizable DHU stem. The full-length sequences and protein-coding genes (PCGs) of the mitogenomes of the three species all had obvious AT biases. The majority of the AT-skew and GC-skew values of the PCGs among the three species were negative, demonstrating bases T and C were more plentiful than A and G. Analyses of Ka/Ks and overall p-genetic distance demonstrated that ATP8 showed the highest evolutionary rate and COXI/COXII were the most conserved genes in the three species. The phylogenetic tree based on PCGs sequences of mitogenomes using maximum likelihood and Bayesian inference analyses showed that three clades were divided corresponding to the subfamilies Caranginae, Naucratinae, and Trachinotinae. The monophyly of each superfamily was generally well supported. The divergence time analyses showed that Carangidae evolved during three geological periods, the Cretaceous, Paleogene, and Neogene. A. indicus began to differentiate from other species about 27.20 million years ago (Mya) in the early Miocene, while D. tabl (21.25 Mya) and A. djedaba (14.67 Mya) differentiated in the middle Oligocene. [ABSTRACT FROM AUTHOR]

Abstract: Effects of Gracilaria verrucosa through competition for nutrients on microalgae were evaluated in the laboratory and in an enclosed sea with an area of 1.72km2 in the northern part of the East China Sea. Results showed that the concentration of NH4-N, NO3-N and NO2-N in the monoculture of G. verrucosa was significantly correlated with that in co-culture of G. verrucosa with Karenia mikimotoi (p <0.01) during the period of experiments, but the concentration of dissolved inorganic nitrogen (DIN) in the monoculture of K. mikimotoi changed little, which indicated that the DIN was mainly absorbed by G. verrucosa in coexistence systems, while the PO4-P in the coexistence assays was absorbed jointly by G. verrucosa and K. mikimotoi. Corresponding to the dramatically decline of the DIN concentration, the K. mikimotoi density was significantly decreased, which indicated that the growth of K. mikimotoi was suppressed by G. verrucosa mainly through competing for nutrients, especially for nitrogen. In the eutrophic seawater with G. verrucosa cultivation, the nutrient concentration was dramatically decreased compared with the control, and synchronously, the phytoplankton population density was also significantly lower compared with the control. Furthermore, the species diversity, richness and evenness were significantly increased during the period of G. verrucosa cultivation, and non-HAB species dominated the phytoplankton population. The results of present paper indicated that G. verrucosa cultivated in the real field would probably suppress the survival and growth of phytoplankton by competing for nutrients, especially for nitrogen. [Copyright &y& Elsevier]

This study investigated the application of cadmium sulfide quantum dots (CdS-QDs) as a photocatalyst to catalyze the conversion of carboxylic acids in the algal bio-crude oil into esters via visible light. The synthesized catalyst was characterized by SEM, TEM, BET, Raman, DRS, PL, and TG-DTA. The analysis of the algal bio-crude oil before and after photocatalytic reaction by gas chromatography‐mass spectrometry showed significant composition changes. The relative content of esters in algal bio-crude oil significantly increased from 17.22% to 47.92%, whereas the relative content of acids significantly reduced. The photocatalyst could selectively stimulate the cleavage of C O linkages in carboxylic acids, leading to the generation of acyl radicals, and ultimately improved the relative content of esters. [Display omitted] • CdS was newly synthesized for algal biocrude oil conversion under visible light. • Esters content in algal biocrude oil increased under visible-light irradiation. • Acids content in algal biocrude oil decreased under visible-light irradiation. • CdS QDs activity was maintained up to four successive regeneration cycles. [ABSTRACT FROM AUTHOR]

• Patatin was purified (up to 96%) and characterized using various methods. • Purified patatin contained up to 76% essential amino acids. • Purified patatin contained fucose. • The effect of patatin on obesity was evaluated using zebrafish. • Patatin has the potential to be used as a natural anti-obesity treatment. Patatin, the major protein found in potatoes, was purified and shows several isoforms. The essential amino acid content of patatin was as high as 76%, indicating that it is a valuable protein source. Patatin was an O-linked glycoprotein that contained fucose monosaccharides, as well as mannose, rhamnose, glucose, galactose, xylose, and arabinose. Patatin had a fucosylated glycan structural feature, which strongly bound AAL (Aleuria aurantia Leukoagglutinin), a known fucose binding lectin. Moreover, the lipid metabolism regulatory effects of patatin on the fat catabolism, fat absorption, and inhibition of lipase activity were measured after high-fat feeding of zebrafish larvae. Results revealed that 37.0 μg/mL patatin promoted 23% lipid decomposition metabolism. Meanwhile patatin could inhibite lipase activity and fat absorption, whose effects accounted for half that of a positive control drug. Our findings suggest that patatin, a fucosylated glycoprotein, could potentially be used as a natural active constituent with anti-obesity effects. [ABSTRACT FROM AUTHOR]