In recent years, large yellow croaker (LYC) has been caught with high abundance in the East China Sea (ECS), which raises concerns about the conservation of LYC resources. We collected LYC samples from spawning grounds and wintering grounds in the offshore Zhejiang from 2020 to 2022. In order to find out the migration route of LYC in the ECS, we made use of otolith microchemical elements by LA-ICP-MS analysis, combined with the clustering analysis and PCA of trace elements such as Ba/Ca, to classify different LYC groups. With the age characteristics of otolith, the habitat patterns of LYC group was studied, and the updated migration route of LYC was speculated. The results showed that groups with Ba/Ca $\leqslant$ 0.004 2 was inhabited in the marine region. That with Ba/Ca $\geqslant$ 0.008 1 was inhabited in the estuary region, and that with 0.004 2 < Ba/Ca < 0.008 1 was inhabited in the mixed (estuary and oceanic) habitat. The five group types of LYC were: (1) offshore spawning, short-term mixed waters inhabited (accounting for 22.2%); (2) offshore spawning, periodically back and forth with mixed water inhabited (accounting for 15.6%); (3) offshore spawning, feeding and nursering in estuary waters, and wintering inhabited in the open sea (31.1%); (4) estuary spawning, nursering in the mixed waters, overwintering inhabited in the open sea (6.7%); (5) shortly spawning in the mixed waters, most of the time inhabited in the open ocean (24.4%). PCA was performed with Ba/Ca core, peak and edge values of all samples, and the results showed that samples from five groups were evenly distributed on both sides of the first axis: G1, G2 and G5 groups, which spent most of their time in the ocean, and G3 and G4 groups, which were heavily influenced by terrestrial sources. At the same time, the PCA results also showed that all the samples appeared nearly synchronously near the island or reefs, indicating that populations in the open sea, offshore and estuary waters may mix due to factors such as migration, indicating the importance of Zhoushan offshore waters for LYC nursering and spawning. This study provides a certain basis for the migration history of the LYC in the ECS between its coastal spawning, feeding grounds and its overwintering grounds in the open sea, as well as for the speculation of its migration routes.

Many of the global ecosystem functions are changing with the loss of biodiversity. It is therefore particularly important to understand the biodiversity-ecosystem functioning (BEF) relationships to support scientific ecological conservation and management. In this study, we evaluated the relationship between environmental factors, biodiversity (species richness and evenness) and ecosystem functions (measured as total biomass) in the benthic fish community of Haizhou Bay, using structural equation modeling (SEM) based on bottom trawl survey data conducted in spring 2013−2022. The results showed that there was a significant positive correlation between species richness and biomass, and a significant negative correlation between evenness and biomass. Among the environmental factors, salinity had significant effects on both species richness and biomass. Regarding the effects of temperature, the temperatures in winter and summer had a stronger effect on biomass than that of annual average temperature. The study suggested that two mechanisms, the niche complementarity mechanism and selection mechanism, may simultaneously play a role in maintaining the biodiversity-biomass relationships in the groundfish communities of Haizhou Bay, and in addition to the fact that such relationships depend on the environmental and habitat conditions.

To better understand the influence of sea surface temperature (SST) on tropical cyclones rapidly intensifying, the characteristics of rapid changes in sea surface temperature and intensity of tropical cyclones in the western North Pacific during 1979−2019 were statistically analyzed using the tropical cyclones best track data compiled by the Shanghai Typhoon Research Institute of the China Meteorological Administration and the sea surface temperature data provided by European Centre for Medium-Range Weather Forecasts. The results indicate the following: (1) About 90% of the rapid intensification of tropical cyclones occurred in summer and autumn, accounting for 32.8% and 56.4% of the total number of rapid intensification respectively. Most tropical cyclones are dominated by rapid intensification across one intensity level, rapid intensification from a severe tropical storm to a typhoon and rapid intensification from a typhoon to a severe typhoon are the two conditions that occur more frequently. (2) The SST conditions greater than 28℃ in summer and 27.5℃ in autumn are conducive to the rapid intensification of tropical cyclones. Lower intensity of tropical cyclones require higher SST (> 29℃) for rapid intensification. The faster translation speed of tropical cyclones is conducive to maintaining high SST environment at its center. (3) When the time variation of SST is within ±0.2℃/(6 h), the horizontal spatial gradient is less than 0.4℃/(°), which is the favorable condition for the rapid intensification of tropical cyclone; the stronger the tropical cyclone is, the more stable the SST environment is needed. (4) When tropical cyclone is a severe tropical storm or above, it is better to judge whether rapid intensification occurs by using only the SST conditions. This work quantifies the SST environment conducive to tropical cyclone intensification and provides a technical reference for quantitative prediction of tropical cyclone intensity evolution based on SST.

Nuclear factor κB (NF-κB) can regulate immunity, inflammation, apoptosis, cell proliferation, and organism development. At present, NF-κB has been well studied in vertebrates and fruit flies, while its role in shellfish is still elusive. In order to further explore the role of NF-κB in the immunity and development of mussel Mytilus coruscus, the full length McNF-κB cDNA sequence was cloned from M. coruscus. McNF-κB gene was 4087 bp long, and the open reading frame was 2 613 bp, encoding 871 amino acids and had a typical ankyrinrepeat (ANK) domain and DEATH domain. The results of amino acid sequence analysis showed that the gene had 72.76% homology with M. edulis and 66.58% with M. galloprovincialis, respectively, and was clustered with M. edulis and M. galloprovincialis in the phylogenetic tree. The real-time PCR (qRT-PCR) technology showed that the McNF-κB gene was expressed distributed in all tissues of M. coruscus, and the expression was the highest in the gill. McNF-κB gene was expressed in both the pediveliger larvae stage and the juvenile stage of M. coruscus, and the expression was significantly higher in the pediveliger larvae stage than that in the juvenile stage. After using RNA interference technology to silence the McNF-κB gene of pediveliger larvae, the larval metamorphosis rate decreased significantly, indicating that this gene was involved in regulating the metamorphosis process of M. coruscus. This study provides a basis for exploring how McNF-κB gene regulates development of M. coruscus.

In this paper, we analyze the variation of local dense shelf water around the Cape Darnley fast ice by using a landfast ice dataset and in-situ observation data of Antarctic elephant seals. The results show that: firstly, there are significant seasonal variations of Cape Darnley fast ice, which has a vital impact on the formation of the Cape Darnley polynya and the local dense shelf water. Secondly, the interannual variation of Cape Darnley fast ice is minimal from 2000 to 2014, with no significant trend of increasing or decreasing. Thirdly, we identify two significant sources of local dense shelf water near the Cape Darnley fast ice area: (1) dense shelf water produced by the strong brine rejection process during the rapid generation of Cape Darnley fast ice from March to April; (2) Cape Darnley fast ice reaching its maximum extent and local brine rejection being reduced to a minimum in May. After the weakening of the inhibition of ice shelf water, the formation of dense shelf water in the upstream MacKenzie Bay polynya is enhanced and transported northwest to the vicinity of the Cape Darnley fast ice. In this study, we preliminarily demonstrates that, in addition to maintaining Cape Darnley polynya, Cape Darnley fast ice probably has an important influence on the generation of local dense shelf water, and points out an important water mass transport path. These would help improve the comprehension of ice-sea interaction near Cape Darnley and point out the need for more observations or modeling studies in this area.

Based on the nonhydrostatic single-phase flow numerical wave model (NHWAVE), the propagation of random waves on a permeable fringing reef is simulated numerically, and the effects of incident wave height, water depth on reef flat, spectrum peak period, thickness of permeable layer, porosity and median diameters the hydrodynamic characteristics of waves on the fringing reef are considered comprehensively, focusing on the variation of sea-swell wave height, infragravity wave height and mean water level along the reef, and comparing with that of the fringing reef without permeable layer. The study shows that the existence of the permeable layer has a significant impact on the hydrodynamic characteristics of waves on the fringing reef. The study shows that the existence of the permeable layer reduces the shallow water deformation of waves on the slope in front of the reef and the wave breaking near the reef edge, and significantly decreases the sea-swell wave height, infragravity wave height, and wave setup near the shoreline, in addition to that, the existence of the permeable layer reduces the maximum wave runup on the shoreline. The greater the incident wave height and spectrum peak period, the more significant the effect of the permeable layer on the sea-swell wave, infragravity wave and wave setup on the fringing reef; when the water depth of the reef is increased, the effect of the permeable layer on wave attenuation is weakened; as the thickness of the permeable layer increases, the values of sea-swell wave height, infragravity wave height and wave setup near the shoreline decrease.

Typhoons are one of the major global environmental disasters, and their variability is of great concern to modern society. However, the variability of typhoon activity and its climate drivers on centennial-millennial scales are less clear due to the lack of atmospheric instrumental records before the mid-19th century. Coastal sedimentary archives provide a means to extend our knowledge of typhoon dynamics, of which the effective identification of typhoon event layers is an important foundation. Although many studies have attempted to reconstruct typhoon activity on long time scales using various indicators and methods, there is still a lack of evaluation of the effectiveness of these indicators and methods for the identification of typhoon event layer. In this study, a high-resolution sedimentary record (Core ZM02) from the muddy belt of inner shelf of the East China Sea was used, and its dating framework was determined using ²¹⁰Pb and ¹³⁷Cs dating methods. The instrumental and sedimentary records were then coupled to analyze the correspondence between typhoon intensity and frequency and sensitivity indicators of typhoon deposits (i.e., sand content and D₉₀ in this study). The results show that the upper 4.5−100 cm of the core dates between 1917 and 2011 AD at a sedimentation rate of 0.97 cm/a. Among the three technical solutions, the threshold method was found to have the best identification and highest stability. Both sand content and D₉₀ were found to be effective indicators for the identification of typhoon deposits in the study area. Sand content may be a potential indicator of typhoon intensity variation along the Zhejiang coast, and D₉₀ contains information on typhoon frequency. The knowledge obtained here will not only contribute to the more accurate use of the sedimentary record to extend the time span of the typhoon record, but also to improve the ability to decipher information from the sedimentary record.

Coccolithophores can produce particulate organic carbon (POC) via photosynthesis and synthesize particulate inorganic carbon (PIC) via calcification; they also make an important contribution to marine carbon cycle. Some studies have reported that ocean acidification generally increases POC content and decreases PIC content of coccolithophores, however, most of the studies show these results under nutrient replete conditions, and a few studies focus on the combined effects of nutrient limitation and ocean acidification on coccolithophores. In this study, we investigated the physiological responses of the coccolithophore Emiliania huxleyi to ocean acidification under dissolved inorganic phosphorus (DIP) limitation. Our data show that ocean acidification and DIP limitation act synergistically to reduce growth rate, relative photosynthetic electron transport rate and light use efficiency of photosynthetic system II of E. huxleyi. Dissolved inorganic phosphorus limitation dominantly increases cellular POC content and offsets the negative effect of ocean acidification on cellular PIC content and the ratio of PIC : POC. Our results suggest that DIP limitation changed the response trends of POC and PIC contents to ocean acidification, which indicates that the contributions of coccolithophores to marine carbon cycle are different in these ocean areas with different DIP concentrations.

As one of the vegetation types with the highest carbon storage in tropical regions, the area of mangrove forest shows a trend of fragmentation and reduction. The spatial distribution and dynamic information of mangrove biomass are crucial to the estimation of greenhouse gas flux and carbon storage, as well as policy formulation and implementation. However, both optical data and SAR data commonly used for biomass estimation have signal saturation phenomenon, and traditional estimation algorithms for mangrove biomass estimation have high data requirements and relatively low estimation accuracy. In order to solve this problem, this study compared the accuracy of four gradient enhanced decision tree algorithms for estimating aboveground biomass (AGB) of invasive mangrove species Sonneria apetala used UAV-LiDAR data, and discussed the importance of variables in the modeling process. The results indicate that: (1) XGBR had a high fitting ability for the estimation of mangrove AGB, reaching R² = 0.833 8, RMSE = 1.55 Mg/hm². (2) The predicted AGB in the study area ranged from 73.10 Mg/hm² to 190.00 Mg/hm², with an average of 109.10 Mg/hm². (3) LiDAR index describing canopy height characteristics is an important variable for estimating mangrove AGB. Conclusion: This study proved the feasibility of UAV-LiDAR data and XGBR model for estimating the AGB of mangrove forests, in order to provide data support for the blue carbon research of mangrove ecosystems.

To understand the characteristics of autophagy induced by virus infection in microalgae Emiliania huxleyi, we used diverse techniques including transmission electron microscopy, fluorescence microscopy, immunolabeling and biochemical methodologies to investigate the role of autophagy in the interaction between E. huxleyi BOF92 and its specific virus EhV99B1. The results showed that virus infection induced autophagy and vacuolar acidification in host cells, concomitant with up-regulation of autophagy-related genes such as atg1, atg5, atg8 and atg12 (p < 0.01) and Vps34 protein involved in the induction and nucleation of autophagosomes (p < 0.01). The expression level of autophagy marker protein p62 was significantly down-regulated (p < 0.05) during viral infection, indicating enhanced autophagic flux and activated autophagy. The expressions levels of negative regulatory factors such as phosphatidylinositol (PI3K), phosphorylated protein kinase B (p-Akt) and phosphorylated target of rapamycin protein (p-TOR) were significantly decreased in the late stage of viral infection (p < 0.01). Moreover, the level of reactive oxygen species (ROS) increased dramatically (p < 0.01), accompanied by a significant reduction in mitochondrial membrane potential (MMP) and ATP levels (p < 0.01) during viral infection. In conclusion, EhV99B1 infection induces ROS production and mitochondrial membrane damage in host cells, and initiates autophagy by regulating the PI3K/Akt/TOR signal pathway. Therefore, autophagy, as a unique form of programmed cell death, is of great significance to the individual survival and population dynamics of phytoplankton respond to environmental and biological stress.