Study on the structure and energy flow of food webs is important for maintaining the stability of structure and function of marine ecosystems, which will contribute to the in-depth understanding of the complex processes of marine ecosystems. Based on the seasonal bottom trawl survey data in the northern waters of Jiangsu Province from 2019−2021, a linear inverse models using a Monte Carlo method coupled with Markov chain model combined with ecological network analysis (ENA) were used to explore the status of the ecosystem and energy flow characteristics of the food web in this area. The results showed that there were 299 energy flow paths in the ecosystem, which showed a typical pyramid structure. In addition, the energy consumed by respiration and the energy flowing into the detritus of each functional group remains synchronized. Compared with other sea areas, connectance (C) and system omnivory index (SOI) were 0.40 and 0.22, respectively, which were at relatively high levels, indicating that organisms from different trophic levels in this ecosystem were closely connected. It has a relatively complex food web structure, which can resist external disturbance. Total primary production/total respiration (TPP/TR) and Finn’s cycling index (FCI) were 1.05 and 5.76%, respectively, indicating that the ecosystem was relatively mature and used energy efficiently. In addition, constraint efficiency (CE), extent of development (AC), synergism index (b/c) and dominance indirect effects (i/d) also indicated high potential for development and regeneration. This study will provide a theoretical basis for the restoration and sustainable utilization of fishery resources in the northern waters of Jiangsu Povince, and provide a scientific basis for the implementation of Ecosystem-based fishery management in this area.

Diaphus is one of the genera with the highest species abundance and the most abundant population in the family Myctophidae, and it is also the dominant group of deep sea fishes in the ocean. However, due to the high similarity of external morphology, it is difficult to identify the lanternfish species. In order to explore the feasibility of otoliths morphological analysis in identifying the otolith differences between Diaphus species with similar otoliths and large overlapping distribution areas, the otoliths of three Diaphus species were collected from the Indian Ocean and the South China Sea for morphometrics analysis with landmark method. The results showed that the morphological variation of sagittal otoliths in three lanternfishes were mainly in the internal main sulcus, and the internal punctuation contribution rate reached 62%. The grid difference visualization showed that the wing length of sagittal otoliths in D. thiollierei was longer than that of the other two species, while the width was slightly narrower. The Bayes function was used for classification and discrimination, and the results showed that the success rate of D. thiollierei was 100%, while the other two species had a few misjudgments. In addition, taking into account the habitat environment and the genetic relationship between these three species, we supposed that the main reason for the morphological differences in the main sulcus of the three spescies was the huge salinity difference in the habitat sea area. However, the impact and physiological mechanism of salinity on the morphology of the main sulcus of sagittal otoliths needs to be further studied.

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.

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.

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.

The inhomogeneity of the seawater medium causes the refraction effect in the sound wave propagation process. The ultra-short baseline system using the planar acoustic array will be affected by this phenomenon during the measurement process, which will cause large errors in the measurement results. The sound ray tracking method is usually used to correct the sound ray by using the measured sound velocity profile. Accurate beam incident angle is the prerequisite to ensure the accuracy of sound ray tracking, but the ultra-short baseline system does not directly measure the beam incident angle but uses the approximate incident angle derived from the acoustic phase difference for sound ray tracking will cause a certain loss of accuracy. To solve the above problems, this paper proposes an iterative correction method of beam incidence angle for ultra-short baseline underwater acoustic positioning. Based on constant gradient acoustic ray tracking, the iterative calculation relationship between beam incidence angle and propagation time is constructed, the Aitken acceleration method is used to quickly solve the nonlinear equation of the beam incidence angle. Simulation experiments prove that the method proposed in this paper can accurately calculate the beam incident angle and target position, and effectively eliminate the influence of refraction effects on ultra-short baseline underwater positioning.

Based on the dataset of 120 water quality monitoring sites (including 16 coastal sites) in rivers along Liaodong Bay, the principal component analysis-multiple linear regression (PCA-MLR) model was used to study the pollution characteristics and flux of organic matter, nutrients and heavy metals, and analyze their possible sources. The pollutants exceeding the first grade of Environmental Quality Standards for Surface Water were COD_Mn, AN concentration. TP concentration and TN concentration, and other water quality parameters met the standard. The TN/TP ratios were high and seriously deviated from the Redfield ratio. The input of high N and low P load from terrestrial sources was the main factor causing the increase of TN/TP in Bohai Sea. DO concentration, EC, AN concentration and TN concentration in non-flood season increased significantly than in flood season, while pH, turbidity, COD_Mn and TP concentration in non-flood season decreased significantly than in flood season. The concentrations of organic matter and nutrients in estuaries were affected by factors such as the agricultural areas that rivers flowed, while the concentrations of heavy metals were related to the distribution of industrial enterprises in the region. The annual fluxes of TN, TP, COD, AN and petroleum pollutant into Liaodong Bay were 3.63 × 10⁴ t, 1 608.5 t, 14.8 ×10⁴ t, 3 086.6 t and 221.9 t, respectively, and the fluxes of Hg, Cd, Pb, As and Cr⁶⁺ were 0.264 t, 0.253 t, 1.978 t, 20.434 t and 31.651 t, respectively. According to their contribution, the main pollution sources were domestic sewage and industrial wastewater, sources caused by hydrological factors (hydrodynamic conditions, etc.), water-gas interface pollutants exchange and secondary sources, non-point sources of farmland runoff and transportation.

Using tide gauge observation, satellite altimeter data, and the result of 10 CMIP6 Earth System Models with good simulation performance, the long-term trend of sea level change in China, and predicts the range of sea level rise in the future are analyzed in this study. The results show that: (1) from 1960 to 2021, the sea level in China’s coastal areas showed an accelerated rising trend, with a rise rate of 2.5 mm/a and an acceleration of 0.06 mm/a². From 1993 to 2021, the rise rate was 4.0 mm/a, higher than the global rate of 3.3 mm/a in the same period. (2) From 1980 to 2021, the sea level rise rates of the Bohai Sea and the Yellow Sea, the East China Sea and the South China Sea were 3.5 mm/a, 3.3 mm/a and 3.6 mm/a, respectively. The sea level rise rates of the Bohai Sea and the Yellow Sea, the South China Sea were relatively fast, while the sea level rise rates of East China Sea was slow. The coastal sea level rose slowly from 1960s to 1970s, and accelerated after 1980s in the Bohai Sea and the Yellow Sea. (3) Under the medium (SSP2-4.5) and high (SSP5-8.5) scenarios, China’s offshore sea level will rise by 0.22 m (0.19−0.28 m) and 0.24 m (0.21−0.33 m) respectively in 2050, and will rise by 0.59 m (0.47−0.80 m) and 0.83 m (0.64−1.09 m) respectively in 2100. (4) During 2021−2040, the median value of sea level rise predicted by statistics is close to the predicted value under the low, medium and high scenarios of the numerical model. During 2041−2060, the predicted values of the low, medium and high scenarios of the numerical model are between the middle and high values of the statistical prediction. During 2081−2100, the high value of sea level rise predicted by statistics is close to that predicted by the medium scenario of the numerical model, the absolute deviation is 0.017 m, and the relative deviation is 3.4%. (5) Under the high scenario, the existing once-in-a-century extreme high sea level in 2100 will become less than 10 year return period, in which more than 50% of the stations will become less than 2 year return period, the defense capacity of coastal protection works and other infrastructure will be reduced, and the risk of flood and other disaster events in complex coastal cities will increase.

Multiple studies have confirmed the long-term property modification of water columns from the bottom to the sea surface at the Southern Ocean and pointed out that it is closely related to the changes of large-scale external forcing. However, the higher frequency interannual variability of the water masses and its causes are still poorly understood, including the winter water (WW), which is the most vulnerable to external forcing near the sea surface. Based on repeated hydrographic observations along 110°E in Januaries 2011 to 2020 and meteorological reanalysis datasets, this study estimated interannual variability of the WW layer in the seasonal ice zone (SIZ) and its possible causes over ten years. Results show that WW properties have significant temporal and spatial variability in this region. A significant positive correlation between the WW core temperature anomaly and the previous-year Antarctic Oscillation (AAO) index anomaly (R = 0.69) and a negative correlation between the AAO index and the turning latitude of the local zonal wind component (R = −0.61), indicate that a larger (smaller) AAO index corresponds to a southward (northward) shift of the divergence zone, and the increase (decrease) of the WW core temperature in the SIZ. A negative correspondence between the local net precipitation anomaly and the WW core salinity anomaly indicates the negative net precipitation anomaly (less freshwater transport to the ocean) after 2016 contributes to an increase in the WW core salinity anomaly. Meanwhile, the local eddy kinetic energy anomaly is negatively correlated with the WW thickness anomaly (R = −0.70), which supports the idea that the enhancement (decrease) in the intensity of persistent cyclonic eddies in this region may strengthen (weaken) the upward pumping to shoal the depth of the circumpolar deep water, and further affect the WW thickness. This study contributes to an in-depth understanding of the specific response of water columns in the Southern Ocean to the high-frequency variability of external forcing.

Two single-scene SAR images observed by Radarsat-2 and Sentinel-1A were decomposed to obtain a pair of SAR sub-aperture images at different azimuth-angles, respectively. Doppler centroid anomaly method was used to invert the sea surface current of two sub-aperture images with different azimuth angles. The current field was obtained by vector synthesis. The inversion results were verified by the HYCOM model data with spatio-temporal matching. The results show that the root mean square (RMS) of the current velocity between the synthesized result by two sub-aperture images of Radarsat-2 and the HYCOM model data is 0.09 m/s, and the correlation coefficient is 0.64. The RMS of current direction is 10.49° and the correlation coefficient is 0.78 of this group data. As for the results of the Sentinel-1A image, the RMS of the current velocity is 0.06 m/s, and the correlation coefficient is 0.82. The RMS of the current direction is 2.85°, and the correlation coefficient is 0.86. It can be seen that the two-dimensional ocean currents field can be effectively inverted based on the two sub-aperture SAR images that decomposed from single-scene SAR image. The inversion accuracy is related to the relative direction of the radar’s looking direction and the real current vector. The inversion accuracy of the sea surface current field can be higher when the relative angle is small.