10 August 2023, Volume 45 Issue 4

    

• 
• Download cover Download table of contents

• Research Papers
• Research on detection method of small and weak targets on sea surface based on short wave infrared

  JIANG Bin, CHEN Yonghua, JIANG Jingbo

  2023, 45(4): 1-5. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.001

  Abstract ( ) PDF ( )

  At present, radar detection and infrared thermal imaging detection are the main detection means for small and weak targets on the sea surface. Radar detection is easy to be interfered by sea echo and atmospheric noise, and the resolution of radar detection is limited. Infrared thermal imaging detection mainly detect the targets by the temperature difference between sea surface target and sea water. The temperature difference between small sea surface target and sea water is very small, and it is easy to be affected by sea clutter, etc. The contrast between target and background is low. Based on the characteristics that the reflectivity of water in the short wave infrared band is almost zero, the short wave infrared was used to detect the small and weak targets on the sea surface, and the gray threshold method was used to extract the small and weak targets on the sea surface. The experimental results show that there was a high contrast between the dim target and the sea surface in the short wave infrared image and the short wave infrared detection was not to be interfered by the sea wave and other background. A simple gray threshold method could be used to detect the sea surface dim target, which was conducive to the real-time detection of the sea surface dim target.
• Evolution analysis of local scour of umbrella suction anchor foundation under Stokes wave and current

  ZHAO Zhen, HU Ruigeng, LIU Hongjun, LENG Hao

  2023, 45(4): 6-15. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.002

  Abstract ( ) PDF ( )

  A wave-suction anchor -seabed interaction model was established by FLOW-3D. The local scour characteristics of umbrella suction anchor foundation in non-cohesive soil under the action of fifth order Stokes wave and current were simulated and analyzed. The characteristics of flow field around the anchor, turbulence characteristics, curve of scour depth with time, erosion image and the influence of different wave height and water depth on local scour were comprehensively analyzed. The results show that the scoured area was mainly concentrated between anchor branches and behind the anchor. The vortices developed best in front of and on the side of the cylinder, and then fell off at the back of the cylinder. The maximum scour depth and deposition height appeared in the scour pit behind the anchor, which were -2.247 m and 0.688 m respectively. The anchor branches can fix ambient soil around foundation. The wave height (H) and water depth (h) had obvious effects on local scour with the increase of wave height and the decrease of water depth, and the local scour became more severe. The depth of scour pit increased gradually, and the scope of deposition moved backward. The difference of maximum scour depth under different wave height and water depth was 0.647 m and 0.714 m respectively.
• Research and engineering application of constitutive parameters of cohesive soil based on small strain hardening soil model

  KOU Hailei, ZHOU Chao, YAN Zhengyu, ZHANG Peng, DIAO Wenzhou

  2023, 45(4): 16-22. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.003

  Abstract ( ) PDF ( )

  The 21^st century is the century of marine resources development. The ocean is widely concerned as a new resource base, and gradually becomes one of the important components for the development of green economy. The stability of the wind power base becomes one of the most concern problems for people. Offshore wind power foundation is not only subjected to structural weight, but also to wave, flow and wind load, which may be damaged due to excessive deformation under complex loads. The operation of offshore turbine is closely related to the deformation of the foundation. Therefore, the point to offshore wind power foundation design controls deformation. Many researchers use numerical simulation to study the characteristics of wind power base. The key point is the selection of appropriate constitutive model. In this paper, the current numerical simulation research situation of offshore turbine were introduced briefly, as well as the advantages and disadvantages of several kinds of constitutive model commonly used. Furthermore, the HSS model was introduced in detail. The focus was put on the advantages and disadvantages of the model, the theoretical basis, methods to determine parameters. The researchers obtained good simulation results by selecting the HSS constitutive model to simulate the small deformation of wind turbine problem. The applicability of the model in simulating small deformation of offshore wind turbine soil was verified.
• Analysis of the characteristics of typhoons affected the Shandong Peninsula from 2011 to 2022

  WANG Qian, SUN Shasha, TENG Fangda, XIANG Chunyi, DONG Lin, YU Qun

  2023, 45(4): 23-30. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.004

  Abstract ( ) PDF ( )

  A total of 15 tropical cyclones affected the Shandong Peninsula from 2011 to 2022, all of which occurred from late June to early September, and concentrated during late July to mid-August. According to the tracks, it was divided into the groups east of the peninsula (9 cases) and west of the peninsula (6 cases). The average generation location of the typhoons in the east group was 6.5 latitudes south than that of west group. The average life maximum intensity in the east group (48.8 m/s) was higher than that of west group (37.5 m/s). While affecting the Shandong Peninsula, although the intensity of the west group (18.7 m/s) was lower than the east group (27.4 m/s), the precipitation was much more severe. The maximum precipitation of the west group was 274 mm, and it showed a growth trend with the year increase (an annual increase of 16 mm). While the maximum precipitation of the nine typhoons in the east group was 170 mm, which changed not much with years. The duration time over land of the landfall TCs that affected the Shandong Peninsula during 2011 to 2021 was 53.9 h in average, which was distinctly longer than the average from 2011 to 2021 (36.6 h).
• A numerical simulation study on the influence of anchorage construction on hydrodynamics of Qinglanbay in Hainan province

  PENG Weiwei, LOU Qi, XU Yandong, FANG Xueyuan, WEI Xiao

  2023, 45(4): 31-39. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.005

  Abstract ( ) PDF ( )

  This paper took Qinglan bay (QLB) in Hainan Province as the research target, and put forward a hydrodynamic model of QLB. Numerical simulation and comparative analysis of the changes of tidal current field, tidal prism and half exchange time were carried out before and after the construction of anchorage projects. The influence of anchorage project construction was systematically analyzed on hydrodynamics of narrow semi-enclosed bay. The results showed that the current speed decreased less than 15 cm/s within the project area, and increased less than 10 cm/s near the northwest corner of the east anchorage and on the north of the two anchorages, comparing with the maximum current speed of the spring tide before construction. The overall variation value of the current speed was within the range of ±15 cm/s in the area no more than 500 m around the anchorage projects. There was a certain increase of the tidal prism in QLB after the construction of the anchorages, with the average increase of 2.15×10⁵m³. The half exchange time of QLB was 71 days. Compared with the half exchange time before (about 85 days), the anchorage projects could significantly affect the water exchange time. The research results would provide scientific basis and technical support for the marine eco-environmental protection and territorial space planning of QLB.
• Numerical simulation of hydrodynamic characteristics of square artificial reefs with different opening forms

  MAO Haiying, HU Cong, WANG Fengyu, WANG Li

  2023, 45(4): 40-47. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.006

  Abstract ( ) PDF ( )

  In order to study the influence of artificial reef with different opening forms on hydrodynamic characteristics, three opening ratios (0.1, 0.2, 0.3) and four opening forms of artificial reef were selected. The CFD method was used to simulate the hydrodynamic field, and the reliability of the model was verified. The variation law of the upwelling scale and drag coefficient of reefs with different opening forms was obtained. The results show that when the shape of the opening was the same, there was a wide range of small flow velocity area in the reef and the back of the square opening, and the flow exchange in the reef and the back of the circular opening was faster. The number of square openings had little effect on the volume of upwelling. The maximum height and volume of upwelling of two open circular reefs were less than four open circular reefs. When the number of openings was the same, the maximum height and volume of upwelling of reefs with circular openings were better than those of reefs with square openings, and the volume of upwelling of reefs with four circular openings was significantly larger than that of reefs with two circular openings.
• Sedimentary sequence and geochemical characteristics of aeolian sands in the Daling section of Donghai island,Guangdong

  YE Yixin, HUANG Rihui, FENG Miaoyan, TANG Daobin, LI Qiaoyun, CHEN Qiwen, LI Siqi , YANG Zhitong, LI Jianxi

  2023, 45(4): 48-54. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.007

  Abstract ( ) PDF ( )

  In this paper, the sedimentary sequences, geochemical characteristics of aeolian sands in the Daling section of Donghai island, Guangdong province, and their indicative climate change were investigated using elemental geochemical analysis in conjunction with radiocarbon dating. The results show that: (1) The compositions of macroelements were mainly SiO₂, Al₂O₃ and Fe₂O₃. (2) The content of active elements had decreased relative to the global upper crust, and the content of relatively stable elements Al and Fe decreased with decreasing depth. (3) The chemical index of alteration reflected the moderate weathering level at that time, and A-CN-K diagram showed that the distribution of sample points was concentrated, reflecting the stable climatic conditions. (4) The climate environment reflected by the Daling section(discussed herein)showed an overall development towards dryness and coolness, during which there were two stages. The first stage showed a warm and humid environment, which contained a period of decreasing temperature and humidity. The second stage showed a decrease in both temperature and humidity compared with the previous phase and an increase in sand drift activities.
• Pollution characteristics and potential sources of heavy metals in wet deposition of Weizhou island in Beibu Gulf

  GUO Zhao, XU Hao, LAI Weilin, ZHANG Chunhua, LIU Guoqiang, LAO Qibin

  2023, 45(4): 55-62. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.008

  Abstract ( ) PDF ( )

  To understand the pollution characteristics and potential sources of dissolved heavy metals (Cu, Pb, Zn, Cd and As) in the atmospheric wet deposition of Weizhou island in the Beibu Gulf, the rainwater samples of Weizhou island were collected in February (winter), May (spring), August (summer) and October (Autumn) in 2018. The results show that the contents of Cu, Pb, Zn, Cd and As in wet deposition of Weizhou island were 0.6 ~ 4.3 μg L^-1, 0.10~1.28 μg L^-1, 9.48~99.3 μg L^-1, 0.13~0.42 μg L^-1 and 0.24 ~ 4.85 μg L^-1, the average of 3.1, 0.50, 29.69, 0.29 and 0.89 μg L^-1, respectively. The highest level of five heavy metals were found in autumn, followed by summer, while lower levels in spring and winter. Compared with other regions, the levels of some metals in Weizhou island was at a high value, and there was a certain pollution load. The highest deposition flux of the five heavy metalswere found in summer, followed by autumn and spring, and the lowest in winter. The annual deposition fluxes of Cu, Pb, Zn, Cd and As were 4.85, 0.77, 45.72, 0.45 and 1.37 mg m^-2 a^-1, respectively. According to the estimation of the road area of Weizhou island, the deposition of Cu, Pb, Zn, Cd and As were 0.12, 0.02, 1.14, 0.01 and 0.03 t a^-1 respectively. The results of the correlation and principal component analysis showed that the wet deposition of heavy metals in Weizhou island was mainly affected by motor vehicle sources and industrial pollution sources.
• Neuroendocrine-immune response of Scylla Paramamosain to acute low salinity stress

  ZHANG Yan, WU Xiangyu, CHEN Qinsheng, TANG Xianming, ZHAO Qun, LI Erchao

  2023, 45(4): 63-72. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.009

  Abstract ( ) PDF ( )

  The effect of acute low salinity stress on the neuroendocrine-immune regulation of crustaceans Scylla paramamosain was determined when S. paramamosain was treated salinity 15 (control) and 5 (treatment), respectively, for 192 h. Low salinity significantly affected the hormone content, biogenic amine content and immune defense index of hemolymph of S. paramamosain within 48 h (p<0.05). The concentrations of corticotropin releasing-hormone (CRH) and adreno-cortico-tropic-hormone (ACTH) significantly increased within 12 h at low salinity (p<0.05), then recovered to the control level in 48 h and remained stable. Dopamine (DA) and norepinephrine (NE) maximized at 12 h (p<0.05), recovered to the control level in 48 h, and then remained stable. The content of 5-hydroxytryptamine (5-HT) significantly increased within 12 h (p<0.05), recovered to the control level in 48 h and remained stable then. Under low salinity stress, the total hemocyte count of S. paramamosain minimized at 12 h and then remained stable, which was significantly different from that of control group (p<0.05). The phagocytosis rate significantly decreased within 12 h (p<0.05), and recovered to the level of control group 48 h later. Crustin-like gene expression in hemocytes and antimicrobial activity in plasma minimized at 12 h (p<0.05), returned to the level of control group at 96 h, and then remained stable. The expression of c-type lectin gene in hemocytes and agglutination activity in plasma significantly decreased after 12 h (p<0.05), gradually recovered to the level of control group at 48 h, and then remained stable. The expression of PPAF and proPO genes and the activity of proPO in hemocytes minimized at 12 h (p<0.05), and gradually recovered to the level of control group at 48 h. The activity of PO increased significantly within 12 h (p<0.05), and then recovered to the level of control group at 48 h. Our findings indicated that S. paramamosain regulates its immune response through neuroendocrine factors like hormones and biogenic amines under low salinity stress, resulting in a short period of immunosuppression. The crab can gradually recover to the normal level within a certain period of time (48 h).
• Effects of morphometric traits of Argopecten irradians on its quality traits

  XU Xiaoying, HU Liping, HE Jiabei, JIANG Liming, YANG Tao, SHI Wenkai, ZHANG Yuheng, LI Wu

  2023, 45(4): 73-78. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.010

  Abstract ( ) PDF ( )

  By analyzing the correlation between morphological traits and weight of bay scallops (Argopecten irradians) and the degree of correlation, establishing the corresponding regression equation, a foundation can be established for the selective breeding of scallops. In this study, 100 bay scallops at seven months of age were randomly selected to measure the shell length (X₁), shell width (X₂), shell height (X₃),body weight (Y₁), soft-tissue weight (Y₂), and adductor weight (Y₃). The correlation coefficients are calculated among traits. Path analysis method was used to calculate the path coefficient, determination coefficient and correlation index with morphological traits as independent variables and weight as a dependent variable. The results showed that there is a positive correlation between the measured morphological traits and weight, and the correlation coefficient reaches very significant (p<0.01). The main factors affecting body weight were shell width and shell height, and the multiple regression equation is Y₁=-39.632+0.778X₂+1.135X₃. The main factors affecting soft-tissue weight and adductor weight were shell height and shell width, respectively, and their multiple regression equations were Y₂=-20.239+0.478X₃ +0.457X₂ and Y₃=-9.596+0.327X₂+0.088X₁, respectively. Our findings provided an ideal measure target for selective breeding of bay scallops. When different quality traits of bay scallop are selected as breeding targets, shell width and shell height should be the preferred indicating trait for body weight, shell height should be the preferred indicating trait for soft body weight, and shell width should be the preferred indicating trait for closed shell muscle weight. Our findings provided a theoretical evidence for formulating multi-trait breeding programs.
• A study on feasibility of discriminating three jumbo squid (Dosidicus gigas) populations inhabiting eastern Pacific Ocean using beak morphology

  LI Jinhui, ZHAO Zhenfang, LIU Bilin, FANG Zhou, HU Guanyu, CHEN Xinjun

  2023, 45(4): 79-87. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.011

  Abstract ( ) PDF ( )

  Jumbo squid (Dosidicus gigas) is abundant and important target economic species of oceanic fisheries. Its beak has a stable morphological structure and is of a great significance in the division of cephalopod species and populations. In order to explore the feasibility of using the morphology of beaks to distinguish the different sized populations of D. gigas based on the samples collected by Chinese squids fishing vessel in the high seas of eastern Pacific Ocean (79°26′W —120°32′W, 02°19′N —20°24′ S) from July, 2018, to December, 2020, ML, BM and 12 morphological parameters of beaks were measured. The morphological differences of beaks between different sexes and different populations were analyzed. Results showed that the variability of morphological parameters of beaks between females and males for small and medium populations was significant except lower hood length (LHL) (p<0.05) while the differences of beak morphometrics between females and maless of large population were significant except upper wing length (UWL) and lower head hood length (LHL) (p<0.05). Results of principal component analysis (PCA) showed that there are differences in beak morphology between females and males. Compared with small and large populations, the overlap between females and males was larger for middle population. The standardized morphological parameters of beaks were used for stepwise discriminant analysis (SDA). Results showed that the discriminant accuracy of large, medium and small populations is 100%, 93.2% and 98.6%, respectively. Our findings indicated that there are differences in the morphological parameters of beaks among three populations of D. gigas, and the beak morphology can be used to distinguish three populations of D. gigas.
• Research Report
• Studies on information extraction and dynamic monitoring of reed-swamp wetland in Bosten Lake based on Sentinel-2 image

  ABUDUREHEMAN·Wusiman, YUSUFUJIANG·Rsuli, ZHANG Xuhui, ZHANG Fa

  2023, 45(4): 88-96. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.012

  Abstract ( ) PDF ( )

  Remote sensing monitoring of wetlands offers a vital technical support for accurately understanding the trends of wetland resource changes. In this study, by focusing on the reed marsh wetland of Bosten Lake, and utilizing Sentinel-2 remote sensing images and field-measured sample point data collected from 2017 to 2022, we extracted wetland distribution information. with the maximum likelihood method, obtained wetland vegetation landscape patterns through landscape index calculations, extracted vegetation coverage with the pixel binary method, and characterized the spatiotemporal distribution of vegetation. The overall classification accuracy of the maximum likelihood method exceeded 80%, demonstrating that it is reliable for extracting wetland information. Between 2017 and 2022, the average wetland area of the studied region is approximately 1.6×10⁵ hm², with a vegetation coverage of about 31.22% and a water body ratio of up to 68.78%. In the northwestern swamp area of Bosten Lake, the expansion of vegetation area was obvious; the total area increased 2.4×10³ hm². In contrast, the water body area exhibited an overall declining trend. The wetland vegetation landscape was less fragmented during the studying period, indicating that vegetation ecosystem is stable. The vegetation coverage in the eastern part of the studying area fluctuated noticeably and interannually. Our findings should serve as a data reference for the wetland resource management and sustainable utilization of Bosten Lake.
• Mariculture-associating TN, TP and COD discharge flux into Laizhou Bay in recent ten years

  SHI Yazhou, SONG Xianli, PANG Shaonan, LI Zhengyan, WU Haiyi

  2023, 45(4): 97-105. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.013

  Abstract ( ) PDF ( )

  As an important mariculture area in northern China, the yield and scale of Laizhou Bay mariculture, especially shellfish culture, have been increasing rapidly in recent years. Against the large-scale and intensive farming, the problem of aquaculture pollution cannot be ignored. Based on the mariculture production data of Laizhou Bay in recent 10 years (2008—2017), the interannual variation of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) into the mariculture area of Laizhou Bay was estimated with discharge coefficient method, and the significant differences among groups were compared. The results showed that the total TN and TP fluxes of mariculture into Laizhou Bay in recent ten years are decreasing with the average of 5 868.30 ±1 364.03 t and 320.54 ±82.96 t, respectively. The COD flux was continuously increasing, with an average of 6 446.06 ±1 382.67 t. There were significant differences in annual TN and TP fluxes among fish, crustaceans and sea cucumbers while no significant difference was found between crustaceans and sea cucumbers. The N/P of aquaculture discharge into Laizhou Bay was about 2.91, and the low N/P affected positively balancing the composition of nutrients in local sea area. The pollutant discharge coefficient method cannot reveal the seasonal difference of pollutant discharge. It is necessary to combine other methods in calculating the monthly flux accurately. In future, the study on aquaculture pollution flux and aquaculture capacity should be strengthened. The coordination and unity of aquaculture production and ecological environment should aid to sustainable development of mariculture.
• An experimental study on dissipating effect of double-layer oyster reefs in Binzhou coastal seawater

  HONG Xin, CHENG Jianting, LI Qingjie, WU Shuang, YAN Jie, SHI Hongyuan

  2023, 45(4): 106-111. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.014

  Abstract ( ) PDF ( )

  In Blue Bay Remediation Action project, oyster reef plays dual roles of ecological restoration and wave suppression. The studies on the effect of oyster reef on wave dissipating is the basis of relevant projects. Taking Binzhou oyster reef ecological restoration project as the object, we studied the wave dissipating effect of stone and hollow oyster reef using a large flume. The experimental results showed that the double oyster reef can achieve a good effect of wave dissipating at high and extremely high water level, respectively. The first layer for wave dissipating occupied more than 68% of the total. At high water level, the first layer wave dissipating rate accounted for 86.7% of the total. Therefore, the current double oyster reef scheme can effectively protect the embankment.
• Ecological characteristics of macrobenthos in coastal subtidal area of Rongcheng

  LIU Xinyu, SHA Jingjing , LIU Yiting, LENG Yu, XU Zhaodong, WANG Zhenzhong, PAN Yulong, ZHANG Jimin, WEN Ruobing, BAO Mengmeng

  2023, 45(4): 112-121. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.015

  Abstract ( ) PDF ( )

  We studied the ecological characteristics of macrobenthic community in the coastal area of Rongcheng and its ecological health status based on the investigation data collected in four seasons, 2016. A total of 163 macrobenthic species were identified. The dominant species throughout the four seasons were Lumbrineris cruzensis, Tharyx multifilis and Heteromastus filiformis. The average biomass of the macrobenthos was 58.89 g·m^-2 and the average abundance estimated from the four cruises was 301.83 ind·m^-2. The Shannon index (H′) of the macrobenthos community varied between 2.50 and 2.58, the species evenness index (J) varied between 0.80 and 0.87 while the species richness index (d) ranged from 1.20 to 1.89. The Bray-Curtis similarity cluster analysis showed that there is a distinct distribution of macrobenthic community from seashore to offshore, which is closely correlated with the spatial structure of bathymetry in the studying region. The benthic biological indices (AMBI and M-AMBI) indicated that the benthic ecosystem in the coastal area of Rongcheng tends to be moderately disturbed. Our findings revealed the community structure of macrobenthos in the coastal area of Rongcheng, which should provide a reference basis for ecological environment protection.
• Characterization of community structure of nekton inhabiting Xiamen and Zhangzhou coastal waters

  LIU Yong, ZHUANG Zhidong, MA Chao, XU Chunyan, SHEN Changchun, CAI Jiandi, XIE Shaoqing

  2023, 45(4): 122-127. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.016

  Abstract ( ) PDF ( )

  Based on the data of fisheries resource surveying from Xiamen and Zhangzhou coastal waters, Fujian, in October (Autumn), 2018 and April (Spring), 2019, species composition, quantitative distribution, dominant species and community biodiversity characteristic of the nekton were analyzed. In total, 204 kinds of nekton in Xiamen and Zhangzhou coastal waters were identified, which belonged to 23 orders, 82 families and 141 genera. The identified included 131 fishes species, 64 crustaceans and 9 cephalopods. There were 3 dominant species, Parapenaeopsis hardwickii, Parargyrops edita, and Trachypenaeus curvirostris in spring and 4 dominant species, Parapenaeopsis hardwickii, Argyrosomus macrocephalus, Portunus hastatoide, and Portunus sanguinolentus in autumn. The stock density in weight in spring and autumn was 239.1 kg·km^-2 and 261.7 kg·km^-2, respectively. The stock density in quantity in two seasons was 24 943 ind·km^-2 and 38 384 ind·km^-2, respectively. The Shannon-Wiener biodiversity index of nekton in spring was higher than that in autumn with an average of 2.342.
• Evaluation of Liaohe Estuary water pollution status based on dynamic distribution of bacterial indicators

  HUANG Huiling, MING Hongxia, LI Mengfei, DAI Yuanyuan, SU Jie, SHI Tingting, JIN Yuan, WANG Bin, FAN Jingfeng

  2023, 45(4): 128-136. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.017

  Abstract ( ) PDF ( )

  It is extremely important to reduce human health risk and improve the water quality management of Liaohe River Estuary. In order to evaluate of the water quality and safety of Liaohe Estuary, we appropriatelky described the dynamic distributions of Enterococcus, Vibrio and other heterotrophic bacteria in the surface water of Liaohe River Estuary in this study, and determined their correlations with major environmental factors. In Jun. and Sept., 2018, Enterococcus, Vibrio and heterotrophic bacteria in the surface seawater of Liaohe Estuary were monitored, and the main environmental and chemical elements in the seawater were assayed. In Jun., 2018, the lowest value of Enterococcus in Liaohe Estuary was not detectable while the highest was 4.0×10¹ CFU·L^-1. In Sept., 2018, the number of Enterococcus varied between 1.0×10¹ CFU·L^-1 and 1.5 ×10³ CFU·L^-1. In Jun., 2018, the highest value of Vibrio was 3.4×10⁶ CFU·L^-1, their lowest value was not detectable while their highest in Sept. reached 3.7×10⁷ CFU·L^-1. The lowest value was not detectable in Jun., 2018, and the number of heterotrophic bacteria in Liaohe estuary varied between 6.93×10⁶ and 8.78×10⁷ CFU·L^-1. In Sept., the number of heterotrophic bacteria varied between 5.67×10⁶ and 6.54×10⁸ CFU·L^{- 1}. The quantity distribution of the three indicators showed a generally higher number in Sept. than in Jun. The number of indicating bacteria is higher in inshore waters than in distant waters. The three indicators significantly correlated with the four environmental factors including DO, phosphate, nitrate and nitrite contents. Our findings reflected the seawater pollution in Liaohe Estuary from the perspectives of fecal and organic pollutions. Multiple stepwise regression analysis was used to construct a correlation regression equation. As was planned, the concentration of pathogenic bacteria may be controlled by regulating the amount of relevant nutrients.
• Community structure of phytoplankton in central and southern Bohai Sea and its relationship with environmental factors

  LIU Xiao, PAN Yulong, WEN Ruobing, LIU Shuang, ZHAO Sheng

  2023, 45(4): 137-145. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.018

  Abstract ( ) PDF ( )

  In order to explore further the relationship between phytoplankton community and environmental factors in central and southern Bohai Sea, the phytoplankton and environmental factors surveying data collected two voyages in May and Sept., 2018 were analyzed. The influence of environmental factors on the phytoplankton community was determined through canonical correlation analysis (CCA). In total, 80 species belonging to 34 genera, 3 phyla were identified, of them, 27 phytoplankton species were identified in May, and 71 species were identified in Sept.. The first dominant species in May was Noctiluca scientillans, and the first dominant species in Sept. was Chaetoceros lorenzianus. The annual average Shannon-Wiener diversity index of the surveyed sea area was 2.42. The average abundance of phytoplankton was higher in May (3.92×10⁴ind/m³ ) than in Sept. (0.51×10⁴ind/m³). High abundance of phytoplankton appeared in the central and northern part of surveyed sea area, and low abundance appeared in the western part of surveyed sea area in May. High phytoplankton abundance appeared in the north and west part of surveyed sea area, and low abundance appeared in eastern and southern area in Sept. The canonical correlation analysis showed that the main factors affecting phytoplankton community were surface temperature, dissolved oxygen, acidity, petroleum and dissolved inorganic nitrogen.
• Current status and changing tendency of eutrophication of Jiaozhou Bay

  WANG Yanling, AN Wenchao, WANG Jinsheng, YAO Chenglin, WANG Ximing, WANG You

  2023, 45(4): 146-150. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.019

  Abstract ( ) PDF ( )

  A continuous investigation was conducted in Jiaozhou Bay, Shandong Province, from 2014 to 2019, 4 seasonal cruises each year. Simultaneously, the temporal and spatial variations of seawater quality indices including chemical oxygen consumption (COD), dissolved inorganic nitrogen (DIN) and reactive phosphate among others were assayed. The results showed that annual mean concentrations of COD, DIN and RP are either close to or better than the class II Seawater Quality Standards while DIN decreased, COD elevated and RP was relatively stable. These findings indicated that the seawater quality of Jiaozhou Bay has been improving steadily. Analysis on the eutrophication status based on data collected in Oct., 2019 revealed that potential eutrophication is low and the proportion of eutrophicated area is about 23.9%, covering mainly the northeast corner of the bay. Phosphorus was found to be a restricting factor in the eutrophicated area. The eutrophication index showed that the area of hypotrophic sea area of Jiaozhou Bay is expanding while the area of eutrophic sea area is decreasing, and the degree of eutrophication is decreasing year by year.
• The distribution characteristics and the pollution evaluation of the heavy metals in the surface sediment of the Yangpu port

  LI Juan, GUO Pengcheng, CHEN Shiquan

  2023, 45(4): 151-157. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.020

  Abstract ( ) PDF ( )

  Spatial distribution characteristics, potential ecological risk and homologous correlation of pollution factors in the surface sediment of Yangpu port were investigated by measuring the contents of Cu, Pb, Zn, Cd, Cr, Hg, As, sulfide, TOC, and petroleum. The results showed that the spatial variation coefficient of petroleum was the largest, followed by Hg and sulfide, and the other factors were smaller. The sediment quality of Yangpu port was good. As might have negative effects on living things and the other six heavy metals seldom had negative effects on living things. The geological accumulation index evaluate of pollution degree was in the following order, Cd>Zn>Pb>As>Cu>Hg>Cr, and Cd was the main pollution factor. In general, the pollution degree of heavy metals in the surface sediment of the Yangpu port was slight ecological harm. The potential ecological risk of the seven heavy metals was in the following order, Hg>Cd>As>Pb>Cu>Cr>Zn, among which Hg and Cd were medium ecological hazards, and the other five heavy metals were slight ecological hazards. The sources of Cu, Zn Cr, Pb and TOC were the same, which were mainly affected by natural and man-made factors such as topography, tidal current and sediment grain size. The sources of Cd and Hg were the same, which were mainly affected by industrial pollution. As, sulfide and petroleum had little or no correlation with other factors, among which As mainly came from the discharge of industrial wastewater, domestic sewage and mariculture wastewater from Yangpu port and its surroundings. Sulfide and petroleum were derived from land-based source pollution. The monitoring and early warning of Hg, Cd and As should be strengthened in the surface sediment of Yangpu port to avoid further harm to human health and marine ecological environment.
• Research Review
• Advances in diel vertical migration investigation of mesopelagic fish species

  TIAN Han, JIANG Yane , ZHANG Jun, XU Shannan, CHEN Zuozhi, ZHU Jiangfeng

  2023, 45(4): 158-166. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.021

  Abstract ( ) PDF ( )

  Mesopelagic fish species are small in size, which inhabit the mid-waters of continental slopes and open ocean (200~1 000 m). They widely distribute in oceans with abundant standing biomass and important ecological functions. Diel vertical migration (DVM) behavior is one of the most pronounce ecological features of these fish species. Mesopelagic fish species transport biological carbon from the epipelagic zone to the deep sea through metabolism during DVM, providing a key carbon source for deep-sea ecosystems. Such process is important for ocean carbon sequestration and carbon cycle of the earth. Studies on the DVM of these fishe species have lasted for over 50 years; however, the studies carried in China are at their infancy. In this review, we summarized the recent progress in the investigation of DVM of mesopelagic fish species at home and abroad, and introduced the results of the investigations on the mechanism of vertical migration of the mesopelagic fish species and their roles in the ocean carbon cycle. We aim to emphasize the importance of mesopelagic fish resources and provide information for the studied on the mesopelagic fish species and mesopelagic ecosystem in China.
• Research progress in sampling, separation and analysis of microplastics in water

  LIN Yang, WANG Yonggang, WANG Xu, AN Zhiqiang, LI Yacui, WANG Hengjia

  2023, 45(4): 167-175. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.022

  Abstract ( ) PDF ( )

  In recent years, the pollution of microplastics in water bodies has aroused widespread concern. However, the analysis and detection of microplastics in water is still in the initial stage, and the comparability of the same type of research is low due to different methods. How to accurately and efficiently collect, isolate and identify microplastics in samples is a key premise for the study of microplastics. Through literature collection and collation, the main methods of sampling, separation and identification of microplastics in water, sediment and aquatic organisms were reviewed, and their advantages and disadvantages were compared. The best use conditions of each method were pointed out, and the research in this field was prospected, in order to provide reference for the current research of microplastics pollution in water bodies.
• Research on comprehensive evaluation of social vulnerability of island seismic disaster

  JIA Jing, WANG Chunxiao, WANG Lingxiao, DOU Shengyu, WANG Weixin

  2023, 45(4): 176-184. https://doi.org/10.13984/j.cnki.cn37-1141.2023.04.023

  Abstract ( ) PDF ( )

  As a bridgehead for the development of marine economy, the island is an important carrier for the national implementation of the marine strategy. Many islands in China are located in the seismically active zone where the Eurasian continent and the Pacific Ocean intersect. However, seismic engineering develops weakly in this field. A comprehensive index system including 20 indicators from three aspects of exposure, sensitivity and resilience was established to evaluate social vulnerability of island seismic disaster. Taking the Zhoushan islands as the study objects, the entropy weight method and the improved TOPSIS model were selected to finish the analysis and calculation about the four island counties, i.e. Dinghai, Putuo, Daishan and Shengsi, aiming at figuring out the relative closeness between evaluative value and ideal solutions and ranking the social vulnerability of the four island counties. The result shows four island counties social vulnerability of island counties seismic disaster, ranking as Daishan, Putuo, Shengsi, Dinghai. The evaluation system established in this study provides research ideas for the quantitative analysis of the social vulnerability of island seismic disaster, and provides instructive significance for island seismic disaster prevention planning and disaster mitigation strategy.