Community composition,abundance and biomass of zooplankton in Zhangzi Island waters,Northern Yellow Sea

Samples were collected monthly from the sea area around Zhangzi Island,northern Yellow Sea,from July 2009 to June 2010.Vertical net towing was used to examine spatial and temporal variability in zooplankton abundance and biomass.Overall,C alanus sinicus and Saggita crassa were the dominant species found during the study period,while the amphipod T hemisto gracilipes was dominant in winter and spring.Vast numbers of the ctenophore species of the genus Beroe were found in October and November.It was not possible to count them,but they constituted a large portion of the total zooplankton biomass.Zooplankton species diversity was highest in October,and species evenness was highest in April.Zooplankton abundance(non-jellyfi sh)and biomass were highest in June and lowest in August,with annual averages of 131.3 ind./m3and 217.5 mg/m3,respectively.Water temperature may be responsible for the variations in zooplankton abundance and biomass.B eroe biomass was negatively correlated with other zooplankton abundance.Longterm investigations will be carried out to learn more about the infl uence of the environment on zooplankton assemblages.     

Two new species of the genusAmphilimna (Echinodermata: Ophiuroidea) from southern China

Two new species of the ophiuriod genusAmphilimna from 280 m depth water east of Hainan Island are described.A. sinica sp. nov. shows affinities withA. transacta (Koehler), andA. granulosa is related toA. cribriformis A. M. Clark. Contribution No. 1432 from the Institute of Oceanology, Academia Sinica.     

Tidal Effects on the Bottom Thermal Front of North Yellow Sea Cold Water Mass near Zhangzi Island in Summer 2009

Three seabed-mounted TD/CTD chains and two upward-looking acoustic Doppler current profilers(ADCPs) in the southwest of Zhangzi Island are used and a simultaneous cruise observation in the northern North Yellow Sea(NYS) is conducted to study temperature variation in the bottom thermal front zone of the NYS Cold Water Mass(NYSCWM) during the summer of 2009. In the flood-ebb tidal cycles, the bottom temperature decreases(increases) during flood(ebb) tides, which are dominated by the tidal-current induced horizontal advection. The ebb tide-induced temperature increase is larger than the flood tide-induced temperature decrease due to seasonal warming. In the spring-neap tidal cycles, the temperature and the vertical temperature structure show notable fortnightly variation from 16 July to 25 August. The bottom temperature increases from neap to spring tides and decreases from spring to neap. The Richardson number demonstrates strengthened vertical mixing during spring tides but enhanced stratification during neap tides. The spring-neap variation in vertical shear caused by tidal current is the dominant factor that induces the fortnightly variation in vertical mixing and thus bottom temperature.     

The Occurrence of Ophiocnemis marmorata （Echinodermata： Ophiuroidea） Associated with the Rhizostome Medusa Rhopilema hispidum （Cnidaria： Scyphozoa）

The association of scyphomedusae with invertebrates has been long known in the literature; especially with hyperiidsamphipods.The association of echinoderms with jellyfish is not common and rarely recorded.We reported the association of theophiuroid Ophiocnemis marmorata with the rhizostome scyphomedusa Rhopilema hispidum collected in Vellar estuary (on thesoutheast coast of India).O.marmorata is supposed to be a filter feeding ophiuroid,quite common in soft bottom of shallow waters.The brittle stars possibly seek for food supply,shelter and protection through the association.     

Diel vertical migration of mesozooplankton in the northern Yellow Sea

The Yellow Sea Cold Water Mass(YSCWM),one of the most vital hydrological features of the Yellow Sea,causes a seasonal thermocline from spring to autumn.The diel vertical migration(DVM) of zooplankton is crucial to structural pelagic communities and food webs,and its patterns can be affected by thermocline depth and strength.Hence,we investigated zooplankton community succession and seasonal changes in zooplankton DVM at a fixed station in the YSCWM.Annual zooplankton community succession was affected by the forming and fading of the YSCWM.A total of 37 mesozooplankton taxa were recorded.The highest and lowest species numbers in autumn and spring were detected.The highest and lowest total densities were observed in autumn(14 464.1 inds./m3) and winter(3 115.4 inds./m3),respectively.The DVM of the dominant species showed obvious seasonal variations.When the YSCWM was weak in spring and autumn,most species(e.g.Paracalanus parvus,Oithona similis,and Acartia bifilosa) stayed above the thermocline and vertically migrated into the upper layer.Calanus sinicus and Aidanosagitta crassa crossed the thermocline and vertically migrated.No species migrated through the stratification in summer,and all of the species were limited above(P.parvus and A.crassa) or below(C.sinicus and Centropages abdominalis)the thermocline.The YSCWM disappeared in winter,and zooplankton species were found throughout the water column.Thus,the existence of thermocline influenced the migration patterns of zooplankton.Cluster analyses showed that the existence of YSCWM resulted in significant differences between zooplankton communities above and below the thermocline.     

Marine fouling in offshore areas east of Hainan Island, northern South China Sea

INTRODUCTIONBiofoulingonunderwaterpartsofman mademarinestructuresisamajoreconomicandtechni calproblemhavinginternationaldimensionsforthedevelopmentofoceanengineeringbecauseitnotonlyincreasesstaticandhydrodynamicloading,butalsoaffectscorrosioncharacteristicsandim pedesunderwaterinspectionandmaintenance (CallowandEdyvean ,1 990 ) .Duetodifferencesingeographicalpositionsandenvironmentalconditions,thedistributionofsessileorganismsvarieswitharea .Therefore ,understandingtheformationofbiofoulin…     

Marine biofouling in offshore areas south of Hainan Island, northern South China Sea

ＩＮＴＲＯＤＵＣＴＩＯＮＢｉｏｆｏｕｌｉｎｇｃａｎｃａｕｓｅｒｏｕｇｈｎｅｓｓｏｆｓｕｂｍｅｒｇｅｄｓｕｒｆａｃｅｓｏｆｍａｒｉｎｅｓｔｒｕｃｔｕｒｅｓ(Ｃｈａｋｒａｂａｒｔｉ,1991),ｉｎｃｒｅａｓｅｈｙｄｒｏｄｙｎａｍｉｃｌｏａｄｉｎｇｓ(ＷｏｌｆｒａｍａｎｄＴｈｅｏｐｈａｎａｔｏｓ,1985),ａｃｃｅｌｅｒａｔｅｃｏｒｒｏｓｉｏｎｐｒｏｃｅｓｓ(Ｐａｔｉｌｅｔａｌ.,1988),ａｎｄｉｍｐｅｄｅｕｎｄｅｒｗａｔｅｒｉｎｓｐｅｃｔｉｏｎａｎｄｍａｉｎｔｅｎａｎｃｅ(Ｈｏｕｇｈｔｏｎ,1978).Ｔｈｅｌａｃｋｏｆｄ…     

First record of Paraonella platybranchia （Hartman, 1961） （Polychaeta： Paraonidae） from the Yellow Sea

This paper reports for the first time a species of polychaetous family Paraonidae, Paraonella platybranchia (Hartman, 1961), a rare species found previously only in the coast near the boundary between the United States and Mexico, and it was recently discovered in the samples collected in 1982 from Chinese side of the Yellow Sea. This is the first record of the species in China as well as in the Northwest Pacific.     

Annual variation in Calanus sinicus abundance and population structure in the northern boundary area of the Yellow Sea Cold Water Mass

The Yellow Sea Cold Water Mass （YSCWM） was suggested as an over-summering site of the dominant copepod species Calanus sinicus in coastal Chinese seas. Population abundance and structure were investigated by monthly sampling along three transects across the northern boundary of the YSCWM during 2009-2010. Results show that thermal stratification existed from June to October and that the vertical thermal difference increased with depth. Generally, total abundance was lowest in October and highest in June, and the female/male sex ratio was highest in February and lowest in August. Evident spatial differences in abundance were observed during the existence of the YSCWM. In June, total abundance averaged 158.8 ind/m~ at well-stratified stations, and 532.1 ind/m3 at other stations. Similarly, high abundances of 322.0 and 324.4 ind/m3 were recorded from July to August inside the YSCWM, while the abundance decreased from 50.4 to 1.9 ind/m3 outside the water mass. C. sinicus distribution tended to even out over the study area in September when the YSCWM disappeared. We believe that the YSCWM may retard population recruitment in spring and preserve abundant cohorts in summer. The summer population was transported to neritic waters in autumn. In addition to low temperatures, stable vertical structure was also an essential condition for preservation of the summer population. C. sinicus can survive the summer in marginal areas in high abundance, but the population structure is completely different in terms of C5 proportion and sex ratio.     

Observed characteristics of tidal currents and mean flow in the northern Yellow Sea

Several bottom-mounted Acoustic Doppler Current Profiler(ADCP) moorings were deployed in the northern Yellow Sea(NYS) during the four seasons of 2006–2007 and also the summertime of2009. A synthesis analysis on the time-continuous records was performed to examine the characteristics and variations of tidal currents and mean flow over the observation period at these stations. Tidal currents accounted for ～75% of the total kinetic energy, with the absolute dominance of M 2 constituent. Visible vertical variations of tidal flow were found on all sites, featured by the decrease of amplitude, increase of rotation rate as well as a decreasing trend of the phase for M 2 component with depth. A notable exception was in the central NYS, where the maximum tidal currents occurred in the upper or middle layers(～20–40 m) instead of near the surface(10 m). The observed mean flow was relatively weak, smaller than15 cm/s. Velocity on the northern end of Yellow Sea Trough(YST) was characterized by low magnitude and an obvious layered structure vertically. In the Bohai Strait(BS) and the northern slope area, the currents weakened and the flow direction presented a major trend to deflect counterclockwise with depth in most observations. Summertime cyclonic circulation around the Yellow Sea Cold Water Mass(YSCWM), its intensification on the frontal zone and the Yellow Sea Warm Current(YSWC) for the winter season were all evident by our direct current measurements. However, the details of water exchange through the BS appeared partly dif ferent from the traditionally-accepted pattern. The vertical dif ferences of tidal and meanflow were larger in summer than that in winter, implying the influence of thermal structure to the local currents. Af fected by the water stratification, mean flow usually reached its maximum near the thermocline in spring and summer, while showing a nearly uniform vertical distribution during winter.     

A new species of Eunice (Polychaeta: Eunicidae) from Hainan Island, South China Sea

Ataxonomic survey of benthic marine animals from coastal regions of Hainan Island, South China Sea, revealed specimens of a new species of Eunice (Polychaeta: Eunicida: Eunicidae), Eunice uschakovi n. sp., collected from the intertidal zone. The species belongs to the group of Eunice that has yellow tridentate subacicular hooks and branchiae scattered over an extensive region of the body. It resembles E. miurai and E. havaica in having both bidentate and tridentate falcigers, but can be readily distinguished by branchial features. Comparisons between E. uschakovi and the two related species are presented.     

Relocation of the Yellow River estuary in 1855 AD recorded in the sediment core from the northern Yellow Sea

Relocation of the Yellow River estuary has significant impacts on not only terrestrial environment and human activities, but also sedimentary and ecological environments in coastal seas. The responses of regional geochemical characteristics to the relocation event, however, have not been well studied. In the present study, we performed detailed geochemical elemental analyses of a sediment core from the northern Yellow Sea and studied their geochemical responses to the 1855 AD relocation of the Yellow River estuary. The results show that TOC/TN, Co/Al₂O₃, Cr/Al₂O₃, Ni/Al₂O₃ and Se/Al₂O₃ ratios all decreased abruptly after 1855 AD, and similar decreases are observed in the sediments of the mud area southwest off the Cheju Island. These abrupt changes are very likely caused by the changes in source materials due to the relocation of the Yellow River estuary from the southern Yellow Sea to the Bohai Sea, which the corresponding decreasing trends caused by the changes in main source materials from those transported by the Liaohe River, the Haihe River and the Luanhe River to those by the Yellow River. Because the events have precise ages recorded in historical archives, these obvious changes in elemental geochemistry of sediments can be used to calibrate age models of related coastal sea sediments.     

A new species of Phyllochaetopterus Grube,1863(Polychaeta:Chaetopteridae) from Hainan Island,South China Sea

Phyllochaetopterus species are widely distributed on the coast of China.Here,Phyllochaetopterus hainanensis n.sp.,a new species collected from Hainan Island(China),is reported.It is characterized by having a V-shaped peristomium,two eyespots covered by a pair of large curved peristomial notopodia(cirri located beneath the palps),13-14 chaetigers in the anterior body region,with three enlarged modified chaetae on the fourth notopodium,and more than five chaetigers in the middle body region.The modified chaeta has a slightly inflated head with an obliquely truncate end.The new species resembles Phyllochaetopterus socialis Claparede,1869,but differs in the shape of peristomial notopodia and peristomium.Twelve species of Phyllochaetopterus have been described from the Pacific Ocean,including the new species described here.An identification key to the known Pacific species is provided together with a brief discussion of the taxonomic value of the eyespots for the genus.     

Sediment consolidation settlement of Chengbei Sea area in the northern Huanghe River subaqueous delta,China

One of the most important factors controlling the morphology of the modern Huanghe(Yellow) River delta is consolidation settlement, which is impacted by fast deposition, high water content, and low density of seafloor sediment. Consolidation settlement of the Huanghe River subaqueous delta was studied based on field data, laboratory experiments on 12 drill holes, and the one-dimensional consolidation theory. Results show that vertical sediment characteristics varied greatly in the rapidly forming sedimentary bodies of the modern Huanghe River subaqueous delta. Sediments in the upper parts of drill holes were coarser than those in the deeper parts, and other physical and mechanical properties changed accordingly. On the basis of the one-dimensional consolidation theory and drilling depth, the final consolidation settlement of drill holes was between 0.6 m and 2.8 m, and the mean settlement of unit depth was at 1.5–3.5 cm/m. It takes about 15–20 years for the consolidation degree to reach 90% and the average sedimentation rate within the overlying 50 m strata was at 5 cm/a to 12 cm/a. This study helps to forecast the final consolidation settlement and settlement rate of the modern Huanghe River subaqueous delta, which provides key geotechnical information for marine engineers.     

Methane in the Yellow Sea and East China Sea: dynamics,distribution, and production

Journal of Oceanology and Limnology - The Yellow Sea (YS) and East China Sea (ECS) are important marginal seas of the western Pacific. Understanding the dynamics of methane (CH4) in the YS and ECS...     

STATISTICAL PROPERTIES OF HIGH-FREQUENCY INTERNAL WAVES IN QINGDAO OFFSHORE AREA OF THE YELLOW SEA

Densely-sampled thermistor chain data obtained from a shallow-water acoustics experiment in the Yellow Sea off the coast of Qingdao were analyzed to examine the statistical properties of the 6 to 520 cpd frequency band internal waves observed. The negative skewness coefficients and the greaterthan-3 kurtosis coefficients indicated non-Gaussianity of the internal waves. The probability distributions were negatively skewed and abnormally high peaks. Nonlinear properties, as exemplified by the asymmetric waveshapes of the internal waves in the offshore area are described quantitatively.     

Preliminary study on pisionids (Annelida: Polychaeta Pisionidae) from Hainan Island coastal waters, South China Sea

Of the four species ofPisione Grube (1856) collected from the coastal waters of Hainan Island, the South China Sea, and described in this paper,Pisione hainanensis n. sp. is new to science;Pisione oerstedii Grube, 1857;Pisione complexa Alikunhi, 1947, and Pisione levisetosa Zhao, Westheide & Wu, 1991 are reported for the first time from this area. Project 38970187 supported by NSFC.     

Population genetic structure of the mantis shrimp Oratosquilla oratoria(Crustacea: Squillidae) in the Yellow Sea and East China Sea

The mantis shrimp O ratosquilla oratoria is an ecologically and economically important species in the Western Pacific. In present study, the population genetic structure of O ratosquilla oratoria from the Yellow Sea and East China Sea was examined with mitochondrial DNA control region sequences. In total, 394 samples were collected from 18 locations and 102 haplotypes were obtained. For the Yellow Sea, the overall nucleotide diversity and haplotype diversity were 0.006 9 and 0.946 8, respectively; while across all the East China Sea locations, the overall nucleotide diversity and haplotype diversity were 0.027 94 and 0.979 0, respectively. The results of AMOVA and pairwise F_(ST)(0.145 2, P 0.001) revealed moderate differentiation between the Yellow Sea and East China Sea populations of O. oratoria. However, neither the neighbor-joining tree nor haplotype network showed clades with geographic pattern, which indicated considerable gene flow was existed between the Yellow Sea and East China Sea, and supporting the high larval dispersal ability in this species. Mismatch distribution analysis and neutrality tests suggested that O. oratoria has undergone population expansion event, and the Pleistocene glacial cycles might have an impact on the historical demography of O. oratoria. The genetic information obtained in this study can provide useful information for sustainable improvements for capture fisheries management strategies.     

An enhanced underwater camera apparatus for seabed observation of megabenthic epifauna in the northern Yellow Sea

Journal of Oceanology and Limnology - Seabed photographing has been applied with various underwater camera apparatuses (UCAs) for observations of megabenthic epifauna, which reveals more details...     

Age,growth,and mortality rate of the yellow goosefish Lophius litulon(Jordan,1902) in the Yellow Sea

With the decline in the most fisheries resources in the Yellow Sea,the yellow goosefish Lophius litulon has increased in commercial and ecological importance in recent years.We studied the length distribution,length-weight relationship,age composition,growth pattern,mortality,and exploitation rates of the yellow goosefish in the Yellow Sea.Total length(TL) of females and males ranged from 173 to582 mm and 178 to 500 mm,respectively.The length-weight relationships were also estimated for females and males.Age classes from 2 to 4 years predominated in the samples.The von Bertalanffy growth function(VB GF),estimated based on non-linear least-squares methodology,showed significant differences between sexes.Females attained a greater estimated asymptotic total length(765 mm TL) compared to males(579 mm TL).The VBGF did not differ significantly between stocks of the northern Yellow Sea and the southern Yellow Sea.Estimated natural instantaneous mortality rate(M) ranged from 0.25/a to 0.33/abased on four age-and length-based methods.Total instantaneous mortality rate(Z) of total samples calculated by the age-based catch curve method was 0.591/a and the average fishing mortality(F) was 0.30/a.Estimated exploitation rate(E) was approximately 0.5,indicating that the population of L.litulon in the Yellow Sea may be sustainable.These results provide a reference for the present status of L.litulon and information for the management.