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.

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.

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.

In this study, the population genetic diversity and structure of Parasesarma affine in the South China Sea were analyzed based on 222 individuals of twelve populations using Cytochrome Oxidase Ⅰ (COⅠ) sequence. A 612 bp fragment of COⅠ gene were sequenced, from which 34 polymorphic sites were tested and 40 haplotypes were defined. The most frequent haplotype was Hap2 with the highest frequency of 69.81%, which was shared in all twelve populations. Total haplotype diversity (H_d) and nucleotide diversity (P_i) were 0.508 9, 0.001 126, respectively, which represented a moderate level of haplotype diversity and a low level of nucleotide diversity. No clustering corresponding to sampling localities was found in neighbor-joining tree and haplotype network. The genetic distance ranged from 0.000 36 to 0.001 73 within populations and from 0.000 48 to 0.001 72 between populations. Genetic fixation index (F_st) and analysis of molecular variance (AMOVA) indicated that the genetic variance mainly came from individuals within populations, and a low level of genetic differentiation among twelve populations. Both neutral test and mismatch-distribution analysis implied that the populations of P. affine had a recent population expansion event that occurred in about 51 000 years ago in the late Pleistocene epoch. In summary, the longer time of the planktonic larval phase and the lack of evident geographical barriers in the marine realm might be major reasons for that P. affine could carry out extensive gene flow and possessed a low level of genetic differentiation among all twelve populations. In addition, the severe climate change of pleistocene epoch might also have important effects on the genetic structure and patterns of distribution of P. affine populations. The research results could provide a theoretical basis for the conservation and utilization of P. affine.

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.

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.

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.

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.

The purpose of this study was to investigate the diversity of actinomycetes collected from the Maowei Sea Natural Reserve of Mangrove in Guangxi, and screen the functional enzymes activities from these actinomycetes. Actinobacterial diversity of Mangrove soil was studied by culturable method and phylogenetic analysis based on 16S rRNA gene sequences. Ten enzyme active substrates were selected as indicator reaction. Activity for functional enzymes was tested by inoculating single colony method. Total of 444 strains of culturable actinomycetes were obtained from mangrove soil environment, they were classified into 63 species, 24 genera, 13 families and 6 orders by 16S rRNA gene sequence analysis. The three strains of them was potential new species. Streptomyces sp. was the dominant genus. Among them, 56 strains were screened with at least one or more enzymes activity. The total positive rate was 88.89%. And two enzymes activity at least could be screened from the 31 strains. And the dominant strains capable of enzyme-producing were of Streptomyces sp., Microbacterium sp. and Curtobacterium sp. Our results showed that in the Maowei Sea Natural Reserve of Mangrove soil, there existed a higher diversity of culturable actinomycetes, and there are large numbers of unknown actionobacterial groups here. These actinomycetes have the abilities to produce excellent functional enzymes.