Size-fractionated phytoplankton standing stock and primary production in the Bohai Sea during late spring

During June 1997 cruise by R/V Science No.l, observations on temporal and spatialvariations of the size-fractionated phytoplankton standing stock and primary production were carried out in the Bohai Sea. The size-fractionated chlorophyll a (Chl a) and primary production, photosynthet-ically available radiation (PAR), as well as the related physico-oceanographic and zooplanktonic parameters were measured at five time-series observation stations representing sub-areas of the sea. Results obtained show that there were the marked features of spatial zonation of Chl a and primary production in the Bohai Sea. The values in the Laizhou Bay, the Liaodong Gulf and the Bohai Gulf were high and showed close relation with tidal fluctuations, i.e. high Chl a concentration occurred during high tide in the Laizhou Bay, and during low tide in the Liaodong Gulf and the Bohai Gulf. In the strait and the central region of the Bohai Sea, the values were relatively low and no relationship with tidal fluctuation could be foun     

应用一种基于产量数据评估方法对东海三个重要渔业的资源评估

Most fisheries in China do not have maximum sustainable yield(MSY) estimates due to limited and poor data.Therefore, finding a common method to estimate MSY or total allowable catch(TAC) for fishery management is necessary. MSYs of three important fisheries in the East China Sea were evaluated through a catch-based model.Estimates for intrinsic rate of increase(r) and five levels of process error were considered. Results showed hairtail Trichiurus japonicas(Temminck and Schlegel) and small yellow croaker Larimichthys polyactis(Bleeker) fisheries experienced overfishing from the mid-1990 s to the early 2000 s, and the suggested TACs were 55.8×10~4 t and9.06×10~4 t, respectively. Decades of overfishing in wintering and spawning grounds of large yellow croaker Larimichthys crocea(Richardson) caused the fishery's collapse in the 1980 s, and it has not recovered until today.The Catch–MSY model generated similar estimated MSYs with other methods and may be a useful choice for the assessment of regional stocks in China.     

中国近海潮汐响应峰值估算的数值模拟

A numerical method is designed to examine the response properties of real sea areas to open ocean forcing. The application of this method to modeling the China’s adjacent seas shows that the Bohai Sea has a highest peak response frequency(PRF) of 1.52 d-1; the northern Yellow Sea has a PRF of 1.69 d-1; the Gyeonggi Bay has a high amplitude gain plateau in the frequency band roughly from 1.7 to 2.7 d-1; the Yellow Sea(including the Gyeonggi Bay), the East China Sea shelf and the Taiwan Strait have a common high amplitude gain band with frequencies around 1.76 to 1.78 d-1 and are shown to be a system that responds to the open ocean forcing in favor of amplifying the waves with frequencies in this band; the Beibu Gulf, the Gulf of Thailand and the South China Sea deep basin have PRFs of 0.91, 1.01 and 0.98 d-1 respectively. In addition, the East China Sea has a Poincare mode PRF of 3.91 d-1. The PRFs of the Bohai Sea, the northern Yellow Sea, the Beibu Gulf and the South China Sea can be explained by a classical quarter(half for the Bohai Sea) wavelength resonance theory. The results show that further investigations are needed for the response dynamics of the Yellow Sea-East China Sea-Taiwan Strait system, the East China Sea Poincare mode, the Taiwan Strait, and the Gulf of Thailand.     

Analyses of egg size,otolith shape,and growth revealed two components of small yellow croaker in Haizhou Bay spawning stock

The geographical variations in life history characteristics of small yellow croaker Larimichthys polyactis, caused by experienced different environmental conditions, have been observed in China seas. Previous studies based on spatial distribution, migration route, and body morphometrics suggested a complex stock structure. In this study, to clarify the source of a spawning stock, we investigated the reproduction strategy and inter-structure of the Haizhou Bay (HZB) spawning stock in the middle Yellow Sea from both egg survey and adult otolith increment analysis. Egg and adult samples were collected from three surveys during spawning season in 2013. Distinct spatial and temporal variations were detected in egg distribution and size, and otolith shape analysis of adult fishes revealed two morphotypes with different increment growth using random forest cluster. The results indicate the existence of two components within the same spawning stock in HZB from different wintering grounds, and accordingly special protection should be required for this stock given the significance to maintain connectivity between adjacent subpopulations.     

黄海南部小黄鱼洄游分布及种群结构特征

Monthly fishery survey data of the small yellow croaker Larimichthys polyactis in the southern Yellow Sea from2003 and 2013 were employed to evaluate the variation in the resource distribution and biological characteristics(especially body length and sex ratio) in the population on a decadal scale.The results indicated that the small yellow croaker migrated from the Shawai fishing ground to the Dasha fishing ground in spring and was mainly distributed in the central and western parts of the Dasha fishing ground in April and May.Larimichthys polyactis in the Dasha fishing ground migrated eastward to offshore wintering grounds in autumn and reached the central Dasha fishing ground in October and November.The small yellow croaker entered the western waters of the Shawai fishing ground in winter.A large number of age 0+ fish occurred in the Shawai and Jiangwai fishing grounds in October of 2003 and 2013.The body lengths of the spawning stock and wintering stock in 2013 were larger than those in 2003,and the monthly sex ratios(female to male) were significantly less than 1 in both years.The monthly distribution of this fish in the southern Yellow Sea was consistent with a previous finding that "the stock migrated between the wintering grounds in the west of Jeju Island and the Lüsi spawning grounds" but tended to move more northward,with the spawning grounds extending outward.In the past decade,body length variation experienced a decline after an increase,rather than a steady decrease.The sex ratio in the single-stick stow net showed a tendency to increase over the decade,but was either less than or more than 1 depending on the fishing gear;therefore,further studies should be conducted to determine the sex structure.     

Lack of mitochondrial genetic structure in the endangered giant clam populations of Tridacna maxima (Bivalvia: Cardiidae: Tridacninae) across the Saudi Arabian coast

The present investigation focuses on population genetic structure analysis of the endangered giant clam species Tridacna maxima across part of the Red Sea,with the main aim of assessing the influence of postulated potential barriers to gene flow(i.e.,particular oceanographic features and marked environmental heterogeneity)on genetic connectivity among populations of this poorly dispersive bivalve species.For this purpose,a total of 44 specimens of T.maxima were collected from five sampling locations along the Saudi Arabian coast and examined for genetic variability at the considerably variable mitochondrial gene cytochrome c oxidase I(COI).Our results revealed lack of population subdivision and phylogeographic structure across the surveyed geographic spectrum,suggesting that neither the short pelagic larval dispersal nor the various postulated barriers to gene flow in the Red Sea can trigger the onset of marked genetic differentiation in T.maxima.Furthermore,the discerned shallow COI haplotype genealogy(exhibiting high haplotype diversity and low nucleotide diversity),associated with recent demographic and spatial expansion events,can be considered as residual effect of a recent evolutionary history of the species in the Red Sea.     

Long-term variation of storm surge-associated waves in the Bohai Sea

When investigating the long-term variation of wave characteristics as associated with storm surges in the Bohai Sea,the Simulating Waves Nearshore(SWAN)model and Advanced CIRCulation(ADCIRC)model were coupled to simulate 32 storm surges between 1985 and 2014.This simulation was validated by reproducing three actual wave processes,showing that the simulated significant wave height(SWH)and mean wave period agreed well with the actual measurements.In addition,the long-term variations in SWH,pattems in SWH extremes along the Bohai Sea coast,the 100-year retum period SWH extreme distribution,and waves conditional probability distribution were calculated and analyzed.We find that the trend of SWH extremes in most of the coastal stations was negative,among which the largest trend was-0.03 m/a in the western part of Liaodong Bay.From the 100-year return period of the SWH distribution calculated in the Gumbel method,we find that the SWH extremes associated with storm surges decreased gradually from the center of the Bohai Sea to the coast.In addition,the joint probability of wave and surge for the entire Bohai Sea in 100-year return period was determined by the Gumbel logistic method.We therefore,assuming a minimum surge of one meter across the entire Bohai Sea,obtained the spatial SWH distribution.The conclusions of this study are significant for offshore and coastal engineering design.     

Numerical study on spatially varying control parameters of a marine ecosystem dynamical model with adjoint method

Based on the simulation of a marine ecosystem dynamical model in the Bohai Sea,the Yellow Sea and the East China Sea,chlorophyll data are assimilated to study the spatially varying control parameters (CPs) by using the adjoint method.In this study,the CPs at some grid points are selected as the independent CPs,while the CPs at other grid points can be obtained through linear interpolation with the independent CPs.The independent CPs are uniformly selected from each 30 × 30 area,and we confirm that the optimal influence radius is 1.2° by a twin experiment.In the following experiments,when only the maximum growth rate of phytoplankton (V m) is estimated by two given types of spatially varying CPs,the mean relative errors of V m are 1.22% and 0.94% while the decrease rates of the mean error of chlorophyll in the surface are 94.6% and 95.8%,respectively.When the other four CPs are estimated respectively,the results are also satisfactory,which indicates that the adjoint method has a strong ability of optimizing the prescribed CP with spatial variations.However,when all these five most important CPs are estimated simultaneously,the collocation of the changing trend of each parameter influences the estimation results remarkably.Only when the collocation of the changing trend of each parameter is consistent with the ecological mechanisms which influence the growth of the phytoplankton in marine ecosystem,could the five most important CPs be estimated more accurately.     

ESTIMATION OF FISHING MORTALITY AND ABUNDANCE OF PACIFIC HERRING IN THE HUANGHAI SEA BY COHORT ANALYSIS (VPA)

In this paper Cohort Analysis (VPA) with the data on catch in number by age and year is used to estimate independently fishing mortality, abundance and actual number of spawning stock of the Pacific herring in the Huanghai Sea. The results show that catch rate of the fishery is very high, and that the fishing mortality of the dominant age group aged 2-4 was 0.87-2.97 during the years 1971-1984. The size of year class has been decreased since 1982 although the variability for this species in the Huanghai Sea is frequent. This results in reducing the recruitment of the fishery, the abundance and the actual number of spawning stock. Therefore, an urgent management measure should be considered.The magnitude of several sources of errors in Cohort Analysis (VPA) are examined, and the precision of the estimates is mainly dependent on an accurate natural mortality.     

The temporal and spatial variability of the Yellow Sea Cold Water Mass in the southeastern Yellow Sea, 2009-2011

The Yellow Sea Cold Water Mass(YSCWM) is one of the important water mass in the Yellow Sea(YS).It is distributed in the lower layer in the Yellow Sea central trough with the temperature less than 10 C and the salinity lower than 33.0.To understand the variability of the YSCWM,the hydrographic data obtained in April and August during 2009–2011 are analyzed in the southeastern Yellow Sea.In August 2011,relatively warm and saline water compared with that in 2009 and 2010 was detected in the lower layer in the Yellow Sea central area.Although the typhoon passed before the cruise,the salinity in the Yellow Sea central trough is much higher than the previous season.It means that the saline event cannot be explained by the typhoon but only by the intrusion of saline water during the previous winter.In April 2011,actually,warm and saline water(T >10 C,S >34) was observed in the deepest water depth of the southeastern area of the Yellow Sea.The wind data show that the northerly wind in 2011 winter is stronger than in 2009 and 2010 winter season.The strong northerly wind can trigger the intrusion of warm and saline Yellow Sea Warm Current.Therefore,it is proposed that the strong northerly wind in winter season leads to the intrusion of the Yellow Sea Warm Current into the Yellow Sea central trough and influenced a variability of the YSCWM in summer.     

Monthly Geographical Distribution of <Emphasis Type="Italic">Nemopilema nomurai</Emphasis> (Scyphozoa: Rhizosotomeae) in the Bohai and North Yellow Seas: a Preliminary Study using Ships of Opportunity

Nemopilema nomurai, an endemic and blooming jellyfish species in the waters of Korea, China and Japan, were monitored from June to October, 2017, in the Bohai and northwestern Yellow Seas, using the ship sighting method, as a preliminary study to investigate the spatiotemporal distribution of medusae. Monitoring revealed that the mass appearance of young medusae was observed in Liaodong Bay in summer. In late summer they disappeared and a high density zone shifted to the mid- and northern Bohai Strait. In early fall, healthy adults with relatively high density were observed in the area around the border of the South and North Yellow Seas. These results suggest that medusae of N. nomurai originated from the Bohai Sea and were advected into the Yellow Sea through the Bohai Strait.     

酸化过程对不同碳酸钙含量的海洋沉积物中总氮及其同位素分析的影响

为节约成本和样品,一些学者同时分析海洋沉积物中的碳、氮及其同位素（TOC、TN、δ¹³C和δ¹⁵N）。分析沉积物中的δ¹³C,需要对样品进行酸化去除无机碳,但是这一酸化过程会使TN和δ¹⁵N的分析结果产生偏差,且偏差范围与沉积物中无机碳含量（CaCO₃）有关。本研究选取了低CaCO₃含量（1-16%）和高CaCO₃含量（20-40%）的海洋沉积物样品,比较了酸化过程对TN和δ¹⁵N的影响。研究结果表明,酸化过程对海洋沉积物中TN和δ¹⁵N的分析结果产生了显著影响。对于低CaCO₃含量的样品,酸化导致样品中TN流失了约0-40%,δ¹⁵N偏移了约0-2‰;而对于高CaCO₃含量的样品,酸化导致样品中TN流失了约10-60%,δ¹⁵N偏移了约1-14‰。表明酸化对TN和δ¹⁵N的影响已经超过了仪器的误差范围0.002%（TN）和0.08‰（δ¹⁵N）,将影响TN和δ¹⁵N的环境指示意义。因此,即使海洋沉积物样品中CaCO₃含量很低,也必须用原样分析TN和δ¹⁵N以避免酸化过程的影响。     

Population Genetic Structure of Rock Bream (<Emphasis Type="Italic">Oplegnathus fasciatus</Emphasis> Temminck &amp; Schlegel, 1884) Revealed by mtDNA COI Sequence in Korea and China

The rock bream, Oplegnathus fasciatus, is a common rocky reef game fish in East Asia and recently has become an aquaculture species. Despite its commercial importance, the population genetic structure of this fish species remains poorly understood. In this study, 163 specimens were collected from 6 localities along the coastal waters of Korea and China and their genetic variation was analyzed with mtDNA COI sequences. A total of 34 polymorphic sites were detected which determined 30 haplotypes. The genetic pattern reveals a low level of nucleotide diversity (0.04 ± 0.003) but a high level of haplotype diversity (0.83 ± 0.02). The 30 haplotypes are divided into two major genealogical clades: one that consists of only Zhoushan (ZS, East China Sea) specific haplotypes from the southern East China Sea and the other that consists of the remaining haplotypes from the northern East China Sea, Yellow Sea, Korea Strait, and East Sea/Sea of Japan. The two clades are separated by approximately 330~435 kyBP. Analyses of AMOVA and F_st show a significant population differentiation between the ZS sample and the other ones, corroborating separation of the two genealogical clades. Larval dispersal and the fresh Yangtze River plume are invoked as the main determining factors for this population genetic structure of O. fasciatus. Neutrality tests and mismatch distribution analyses indicate late Pleistocene population expansion along the coastal waters of Korea and China approximately 133–183 kyBP during which there were periodic cycles of glaciations and deglaciations. Such population information needs to be taken into account when stock enhancement and conservation measures are implemented for this fisheries species.     

温度、盐度和光照对浒苔生长和光合作用的影响

Intensive Pyropia aquaculture in the coast of southwestern Yellow Sea and its subsequent waste, including disposed Ulva prolifera, was speculated to be one of the major sources for the large-scale green tide proceeding in the Yellow Sea since 2007. It was, however, unclear how the detached U. prolifera responded and resumed growing after they detached from its original habitat. In this study, we investigated the growth and photosynthetic response of the detached U. prolifera to various temperature, salinity and irradiance in the laboratory. The photosynthetic rate of the detached U. prolifera was significantly higher at moderate temperature levels(14–27°C)and high salinity(26–32), with optimum at 23°C and 32. Both low(14°C) and highest temperature(40°C), as well as low salinity(8) had adverse effects on the photosynthesis. Compared with the other Ulva species, U. prolifera showed higher saturated irradiance and no significant photoinhibition at high irradiance, indicating the great tolerance of U. prolifera to the high irradiance. The dense branch and complex structure of floating mats could help protect the thalli and reduce photoinhibition in field. Furthermore, temperature exerted a stronger influence on the growth rate of the detached U. prolifera compared to salinity. Overall, the high growth rate of this detached U. prolifera(10.6%–16.7% d~(–1)) at a wide range of temperature(5–32°C) and salinity(14–32) implied its blooming tendency with fluctuated salinity and temperature during floating. The environmental parameters in the southwestern Yellow Sea at the beginning of green tide were coincident with the optimal conditions for the detached U. prolifera.     

基于稳定同位素分析推定秋冬季南极半岛南极大磷虾营养变化

南极大磷虾（Euphausia superba）为南大洋生态系统中的关键种,也是南极生态系统食物网中的重要枢纽。该种秋冬季转换期的营养信息对于理解其知之甚少的越冬机制非常重要。但关于此方面的少数研究在时空变化上仍存在着差异。为此,我们调查了南极半岛秋季（4-5月）和冬季（6月）磷虾成体δ¹³C和δ¹⁵N值的个体、月份及区域性差异。我们的目标旨在检验该期间磷虾的营养变化以及磷虾与其在南极海洋生态系统中的摄食环境之间的关系。结果如下：（1）磷虾δ¹³C值与体长之间无显著关系,但δ¹⁵N值与体长之间则存在显著相关性;（2）秋季磷虾δ¹³C值呈现增长趋势,但冬初季节并无显著变化,此期间δ¹⁵N值无显著不同;（3）布兰斯菲尔德与南设得兰群岛之间的δ¹⁵N平均值显著不同。我们的数据表明南极半岛秋至初冬转换期间磷虾成体营养呈现个体、季节性及区域性变化。     

黄海小黄鱼生物学特征对多重压力的响应

Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased substantially, in particular, average length of fish in 2008 was reduced by ~85% than those occurring in 1985, and at that time ~93% of the total catch was dominated by one-year-old individuals. Correspondingly, growth parameters also varied significantly over the years, i.e., k(growth coefficient) and t_0(zero-length age) gradually increased from 0.26 and –0.58 year in 1960 to 0.56 and –0.25 year in 2008, respectively. Although, L∞(body length)sharply decreased from 34.21 cm in 1960 to 24.06 cm in 2008, and t_r(inflexion age) decreased from 3.78 year in1960 to 1.61 year in 2008. There was a great increase both in natural mortality coefficient and fishing mortality coefficient. However, according to the gray correlation analysis, changes in the biological characteristics of small yellow croaker were induced by different stressors ranked as: fishing vessel powerfeeding gradesea surface temperature. This study suggests that the active fishery management measures for biological characters of fish populations should be considered.     

C波段紧缩极化SAR海冰探测能力评估

The C-band synthetic aperture radar(SAR) data from the Bohai Sea of China, the Labrador Sea in the Arctic and the Weddell Sea in the Antarctic are used to analyze and discuss the sea ice full polarimetric information reconstruction ability under compact polarimetric modes. The type of compact polarimetric mode which has the highest reconstructed accuracy is analyzed, along with the performance impact of the reconstructed pseudo quad-pol SAR data on the sea ice detection and sea ice classification. According to the assessment and analysis, it is recommended to adopt the CTLR mode for reconstructing the polarimetric parameters σ_(HH)~0,σ_(VV)~0, H and α,while for reconstructing the polarimetric parameters σ_(HV)~0, ρ_(H-V), λ_1 and λ_2, it is recommended to use the π/4 mode.Moreover, it is recommended to use the π/4 mode in studying the action effects between the electromagnetic waves and sea ice, but it is recommended to use the CTLR mode for studying the sea ice classification.     

Stable isotopes in deep-sea living (stained) foraminifera from the Mozambique Channel (eastern Africa): multispecies signatures and paleoenvironmental application

Oxygen and carbon isotopes (δ¹⁸O and δ¹³C) have been investigated in carbonate tests of deep-sea foraminifera living in the Mozambique Channel (eastern Africa) to understand how environmental constraints (e.g., organic matter, oxygenation) control the intra- and interspecific variability of isotopic signatures. 197 living individuals, including eight different species, from various microhabitats within the sediment were sorted from sediment samples gathered at two stations on the Malagasy upper slope. Results show that the δ¹⁸O values of foraminiferal taxa were not controlled by microhabitat pattern. They presented tremendous and intriguing intraspecific variability that is not explained by the classical ontogenetic effect. The δ¹³C values of infaunal foraminiferal taxa do not show a 1:1 relationship with the bottom water δ¹³C DIC and do not present a constant offset from it; instead, they appear to be mainly controlled by a microhabitat effect. The lower δ¹³C values of shallow, intermediate, and deep infaunal taxa at the deeper station compared to those seen at the shallower station reflect the enhanced exportation of sedimentary organic matter at the sediment–water interface, and its related mineralization within the upper sediments. The ?δ¹³C between shallow/very shallow infaunal species (i.e., Hoeglundina elegans, Uvigerina hispida) and intermediate/deep infaunal species (i.e., Melonis barleeanus, Globobulimina barbata) permits insight into (1) the exportation of organic matter to the seafloor and (2) the various degradation pathways for organic detritus in the benthic environments off NW Madagascar.     

北黄海冷水团对獐子岛微微型浮游生物分布的影响

Picoplankton distribution around the Zhangzi Island(northern Yellow Sea)was investigated by monthly observation from July 2009 to June 2010.Three picoplankton populations were discriminated by flow cytometry,namely Synechococcus,picoeukaryotes and heterotrophic prokaryotes.In summer(from July to September),the edge of the northern Yellow Sea Cold Water Mass(NYSCWM)resulting from water column stratification was observed.In the NYSCWM,picoplankton(including Synechococcus,picoeukaryotes and heterotrophic prokaryotes)distributed synchronically with extremely high abundance in the thermocline(20 m)in July and August(especially in August),whereas in the bottom zone of the NYSCWM(below 30 m),picoplankton abundance was quite low.Synechococcus,picoeukaryotes and heterotrophic prokaryotes showed similar response to the NYSCWM,indicating they had similar regulating mechanism under the influence of NYSCWM.Whereas in the non-NYSCWM,Synechococcus,picoeukaryotes and heterotrophic prokaryotes exhibited different distribution patterns,suggesting they had different controlling mechanisms.Statistical analysis indicated that temperature,nutrients(NO3–and PO43–)and ciliate were important factors in regulating picoplankton distribution.The results in this study suggested that the physical event NYSCWM,had strong influence on picoplankton distribution around the Zhangzi Island in the northern Yellow Sea.     

胶州湾沉积物中有机质的来源与组成及其对百年尺度环境变化的指示

The Jiaozhou Bay is characterized by heavy eutrophication that is associated with intensive anthropogenic activities. Four core sediments from the Jiaozhou Bay are analyzed using bulk technologies, including sedimentary total organic carbon(TOC), total nitrogen(TN), the stable carbon(δ~(13)C) and nitrogen(δ~(15) N) isotopic composition to obtain the comprehensive understanding of the source and composition of sedimentary organic matter and further shed light on the environmental changes of the Jiaozhou Bay on a centennial time scale.Results suggest that the TOC and TN concentrations increase in the upper core, having indicated a probable eutrophication process since the 1920 s in the inner bay and the 2000 s in the bay mouth. The TOC and TN concentrations outside the bay have also changed since 1916 owing to the variation of terrigenous input.Considering TOC/TN ratio, δ~(13) C and δ~(15) N, it can be concluded there is a mixture of terrigenous and marine organic matter sources in the study area. A simple two end-member(terrigenous and marine) mixing model usingδ~(13) C indicats that 45%–79% of TOC in the Jiaozhou Bay is from the marine source. The environmental changes of the Jiaozhou Bay are recorded by geochemical proxies, which are influenced by the intensive anthropogenic activities(e.g., extensive use of fertilizers, and discharge of sewage) and climate changes(e.g., rainfall).