In order to cope with the declining fishery resources, stock enhancement has become one of the main methods of restocking and maintaining the sustainable use of resources. After the implementation of enhancement, the sustainable characteristics of fishery resources are a problem that scholars generally care about, but can not be effectively solved by using traditional surplus production models. Based on the traditional Schaefer surplus yield model, this study proposed a surplus production model (enhancement surplus production model) suitable for the case of stock enhancement, and simulated and analyzed the effects of different enhancement and fishing strategies on the model. The form of this model is similar to the Schaefer surplus production model, but it adds a parameter describing the growth characteristics of the enhancement stock-the effective enhancement rate (e) to express the impact of the stock enhancement on the yield. The results show that reasonable enhancement quantity can increase the maximum sustainable yield (MSY), and the use of the enhancement surplus production model can obtain reasonable estimates of MSY and other key indicators. Compared with the non-enhancement situation, under the influence of stock enhancement, the biomass required to reach MSY (B_MSY) is small, while the maximum sustainable fishing effort (E_MSY) increased. Inhibition occurs between the existing stock (the stock that originally existed in the sea area) and the enhancement stock reflected in the enhancement surplus production model. Under the influence of this effect, different enhancement and fishing strategies will affect the assessment results of the model. Compared with the traditional model, this model assesses the MSY under the effect of stock enhancement, and improves the accuracy of the results, which can be used to estimate the MSY of enhancement species in well-defined sea areas such as marine ranching.

In order to study the relationship between the open South China Sea Sthenoteuthis oualaniensis fishing ground and the marine environmental factors, this article is based on the data of fishing net fishing boat production and remote sensing of marine environment from 2013 to 2018 in Beihai, Guangxi Zhuang Autonomous Redion. The relationship between the spatiotemporal distribution of the fishing ground of Sthenoteuthis oualaniensis and sea surface temperature (SST), sea surface height (SSH) and sea surface chlorophyll a (Chl a) concentration were studied. The results showed that in the sea areas of 5°−20°N and 108°−118°E, the three environmental factors of SST, SSH and Chl a concentration had a great influence on the spatial and temporal distribution of the fishing ground of Sthenoteuthis oualaniensis. The suitable values of SST, SSH and Chl a concentration within the fishing Sthenoteuthis oualaniensis ground of oualaniensis were: 25−31℃, 46−80 cm, 0.05−0.27 mg/m³, and the center of gravity of the fishing ground shifts from south to north. In addition, the K-S test was performed on the relationship between CPUE values and marine environmental factors from January to December 2013−2018, and the results showed that there was no significant difference between the CPUE values and marine environmental factors.Therefore, the three environmental indicators SST, SSH and Chl a concentration can effectively characterize the resource density of the Sthenoteuthis oualaniensis and the distribution of the central fishing ground.

Algae are general term of a large group of photoautotrophic aquatic sporophytes. Along with the long earth history, the algal light-harvesting antenna has evolved special structure and function, to adapt to low-light underwater environment. Since the algal light-harvesting antennas were first discovered 70 years ago, the progress of structural analysis can be divided into four stages. The first stage was from 1950 to 1980, and effects were focused on studying the structural composition of light-harvesting antenna through biochemical and spectral techniques. The second stage was from 1980 to the present, and X-ray crystallization becomes a primary tool to study the partial fine-structure of the complete complex. The third stage was from 1980 to 2010. In this stage, complete contour structure can be studied by using electron microscope (EM). The fourth stage is from 2010 to the present, and the use of cryo-EM technology to studied intact fine-structure has brought the blowout period of structural analysis in recent year. With the rapid development of cryo-EM technology, a variety of complete fine-structures of algal light-harvesting antenna complexes have been analyzed, including cyanobacteria, red algae, green algae, and diatoms. Specifically, in 2019, multiple super-molecular complex structures of algal light-harvesting antenna were resolved. This breakthrough provides us valuable structure information for the study of energy transfer and the unified relationship between structure and function. However, the synthetic understanding of the relationship between the structure, function, environment, and applications of algal light-harvesting antennas is still preliminary, compared to the huge demand of solar energy utilization from bio-materials. Therefore, further research on the light adaptability of light-harvesting proteins has become the focus of the future, and will provide a sufficient scientific basis for the application of algal light-harvesting antenna proteins in the field of photoelectric devices.

Coelomocytes in Apostichopus japonicus, present in coelomic fluid and water-vascular system, are considered to participate in a variety of biological functions including nutrition transport, metabolism and immunity. In the process of evisceration, coelomocytes in coelom are nearly exhausted and then recovered in a short period. The polian vesicle, as the only remained internal organ after evisceration, shows positive response that coelomocytes within it increased rapidly. Coelomocytes in coelom are nearly exhausted after evisceration, and then recovered quickly. To further investigate the function and significance of the rapid increase of coelomocytes in the early stage of regeneration after evisceration, transcriptome sequencing was performed for coelomocytes in polian vesicle and coelom of A. japonicus at 6 h after evisceration and pre-evisceration, respectively. The gene expression differences of coelomocytes in polian vesicle and coelom after evisceration were analyzed compared to those of healthy A. japonicus. These results showed that 267 genes were differentially expressed in coelomocytes of polian vesicle at 6 h after evisceration, and most of these genes were enriched into the enzyme catalytic activity subclasses according to GO functional annotation and glycine, serine and threonine metabolism pathway according to KEGG pathways annotation, respectively. Additionally, 922 differential genes were significantly expressed in coelomocytes of coelom at 6 h after evisceration, and these genes were enriched into cell adhesion and biological adhesion subclasses according to GO functional annotation and ECM-receptor interaction, TGF-β signaling pathway, FoxO signaling pathway according to KEGG pathways annotation, respectively. The results provide an important basis for further functional research and the regeneration mechanism of coelomocytes after evisceration in A. japonicus.

Plastics accumulate in the environment and gradually break into microplastics (MPs, size below 5 mm). It poses a serious threat to the environment and human health. In this study, a strain LC-2 capable of degrading polyethylene (PE) was isolated from plastic films collected from the Licun Estuary of Qingdao. It was identified as Bacillus aquimaris by using a combination of molecular biological technique with morphological, physiological and biochemical characteristics. After the strain was isolated, it was cultured in a liquid medium for 28 days with PE as the sole carbon source. The polyethylene was subsequently separated and examined with a scanning electron microscopy, a contact angle test, a thermogravimetric analysis and a Fourier transform infrared spectrum analysis. The results showed that the weight loss of PE was about 9% after the degradation, with apparent morphologic changes on the surface of PE. It was also showed that the hydrophobicity of PE became smaller, with surface oxidation to produce −C=O functional groups. These evidences are sufficient to prove that the strain LC-2 can degrade PE.

We analyzed δ³⁰Si of dissolved silicate of surface seawater from the Pacific Ocean, Indian Ocean and Atlantic Ocean. The results showed that the δ³⁰Si of the Pacific Ocean surface seawater was 0.45‰−2.91‰, withan average value of (1.52±0.59)‰; the δ³⁰Si of the Indian Ocean surface seawater was 0.98‰−2.30‰, with an average value of (1.52±0.36)‰; the δ³⁰Si value of the Atlantic Ocean surface seawater was 0.90‰−2.23‰, the average value was (1.55±0.35)‰. The silicon isotope in the ocean surface layer mainly shows the correlation with the ocean surface circulation and meridional overturning current, and its distribution characteristics are mainly affected by the biological activities in the surface water and the mixing between different water masses caused by the movement of the surface ocean currents. The mixing effect perhaps has a significant effect on the distribution of δ³⁰Si in the surface water of the open oceans.

The distribution of dissolved manganese (DIMn) and manganese in surface sediment in the Sanggou Bay were investigated in April, August, October 2011 and January 2012. The concentrations of DIMn and manganese in surface sediment were measured by the the catalytic-kinetic spectrophotometric and two-step extraction method, respectively. The results showed that the average concentration of DIMn in 2011−2012 were (60.5±43.1) nmol/L in April, (42.0±30.5) nmol/L in August, (23.4±11.2) nmol/L in October and (18.2±13.5) nmol/L in January. The high concentrations of DIMn always being found in the estuary and decreased from nearshore to the coastal area. There exists significant seasonal variation for concentrations of DIMn with highest value in spring, followed by summer and autumn, and lowest value in winter. The concentrations of DIMn in the Sanggou Bay were higher than the Ailian Bay and the Lidao Bay in spring and summer, and with insignificant variation in autumn and winter. The average content of total manganese (TMn_s) in surface sediment were (861±308) mg/kg in April 2011, (915±322) mg/kg in August 2011, (589±108) mg/kg in October 2011 and (653±185) mg/kg in January 2012. The average content of acetic acid-soluble manganese (HAc-Mn) in surface sediment were (500±272) mg/kg in April 2011, (502±232) mg/kg in August 2011, (322±81) mg/kg in October 2011, (345±91) mg/kg in January 2012. The content of TMn_s and HAc-Mn in the sediment of the bay were both decreased with the increasing distance from the coast. There exists significant seasonal variation for concentrations of HAc-Mn in the surface sediments during the investigations, with higher concentrations occurred in spring and summer than that in autumn and winter. The adsorption of SPM and utilization of plankton were important factors affecting the content and distribution of DIMn in the Sanggou Bay. The major sources for DIMn in the Sanggou Bay included the inputs from riverine, groundwater discharge, atmospheric deposition and release from the sediment-water interface. The major sinks for DIMn included the output into the Yellow Sea and the absorption or accumulation by biological activities. A preliminary box model was established to estimate the budgets of DIMn for the Sanggou Bay, which demonstrated that in addition to output into the Yellow Sea and biological activities, there was other sinks of DIMns in the Sanggou Bay. The results provide basic data for further understanding the biogeochemical cycle of DIMn in the Sanggou Bay.

Marine microplastics pollution is an emerging marine environmental issue and has attracted worldwide attention. Due to the special geographical environment characteristics, the coastal bays become the hotspot for microplastics distribution research. Here we report data on the abundance and characteristics of microplastics collected from surface seawater of the Jinzhou Bay. Samples were collected from 11 sites by horizontal trawling of a plankton net in October 2017. Wet peroxide oxidation process and micro Fourier-transform infrared absorption spectroscopy were conducted to remove the organic material mixed in the sample and identified the composition of microplastics. The research results showed that the average abundance of microplastics in the Jinzhou Bay was (0.93±0.59) items/m³, and accounting for 96.2% of the total plastic debris. Polypropylene and polyethylene were the main components of microplastics, accounting for 55.0% and 23.5%, respectively. The main types of microplastics were lines and fragments, accounting for 41.7% and 26.2%, respectively. White, blue and translucent was the most common color, accounting for 35.1%, 26.0% and 21.4%, respectively. Affected by hydrodynamic conditions and riverine input, the spatial distribution of microplastics in the surface seawater of the Jinzhou Bay was higher in the north areas than that in the south.

In order to study the physiological effects of different salinity stress on Larimichthys polyactis, the four-month-old L. polyactis (body weight (12.6±3.1) g) cultured in natural seawater with salinity of 22.1 were applied to salinity stress in seawater salinity of 5 (called as low-salinity group) and 34.5 (called as high-salinity group), and natural seawater was used as a control group. After 10 days of acute salinity stress experimental treatment, the activities of superoxide dismutase (SOD), catalase (CAT), alkaline phosphatase (AKP) and acid phosphatase (ACP) in the liver and Na⁺/K⁺-ATPase in gills and kidneys were measured and analyzed. The results showed that under acute salinity stress, the activity of antioxidant enzymes (SOD and CAT) in the liver were increased. Among them, the activities of SOD in the low-salinity group and CAT in the high-salinity group were significantly higher than those in the control group (p<0.05). Under different salinity conditions, AKP and ACP showed an opposite trend of change, i.e. AKP activity gradually increased with increasing salinity, while ACP activity gradually decreased. Additionally, Na⁺/K⁺-ATPase activity in gills was the lowest in the low salinity group, and the activity of which in the kidney in the high salinity group was significantly higher than that of the control group (p<0.05). The above research results indicate that juveniles of L. polyactis can still survive normally when the salinity drops to 5, without obvious abnormality. And different salinity stress can significantly affect the non-specific immune enzymes activities of the liver, and the Na⁺/K⁺-ATPase activity of the gills and kidneys in L. polyactis. In other word, the tissues of liver, gill and kidney play an important role during the process of L. polyactis adapting to changes in salinity. The research results also provide a reference for the cultivation of L. polyactis in high-saline or brackish water areas.

Dinoflagellate cysts, as micro-fossil, could be used to trace environmental change history, such as water eutrophication and climate change. But there is controversy on how to indicate water eutrophication, and also it is a problem how to differ the signals between water eutrophication and climate change in dinoflagellate cysts. In order to address these problems, we collected four sediment cores in the Changjiang River Estuary and analyzed their dinoflagellate cysts. Results showed that eutrophication could lead to the increase of total dinoflagellate cysts and Paralytic Shellfish Poisoning (PSP) productive dinoflagellate cysts abundance. And the ratio of hetero/autotrophic dinoflagellate cysts decreased, which implied that the eutrophication mainly resulted from agriculture and domestic sewage in the Changjiang River Estuary. Because of water plume, the eutrophication signal was relatively weak near estuary, strong in middle distance and almost none in far distance. Seasonal change of dinoflagellate cysts was observed in the high sediment sinking area in the estuary, with the lowest production in winter as a result of low temperature. ENSO events will lead to the peak and valley value of dinoflagellate cysts abundance by affecting nutrient input which is transferred by river downloading. Moreover, the signal also varied with the distance: valley and peak value of dinoflagellate cysts present because of strong and weak river runoff pulse near estuary, peak and valley value of dinoflagellate cysts and runoff overlapped and were clear in middle distance, and peak value of dinoflagellate cysts was obvious in far distance but the domain reason was complex. These findings are of great significance to environment history reconstruction, study of red tide history and ENSO events.