Spatio-temporal distribution of net-collected phytoplankton community and its response to marine exploitation in Xiangshan Bay

To explore the spatial-temporal distribution of the phytoplankton community and evaluate the combined effects of marine resource exploitation, net-collected phytoplankton and physical-chemical parameters were investigated in the Xiangshan Bay during the four seasons of 2010. A total of eight phyla, 97 genera, and 310 species were found, including 232 diatom species, 45 dinoflageUate species and 33 other taxa. The phytoplankton abundances presented a significant （P〈0.001） seasonal difference with the average of 60.66x104 cells/m3. Diatoms （mainly consisting of Coscinodiscus jonesianus, Cerataulina pelagica, Skeletonema costatum, and genus Chaetoceros） dominated the phytoplankton assemblage in all seasons. We found great spatio-temporal variation in community composition based on the multidimensional scaling and similarity analysis. Canonical correspondence analysis show that temperature, nutrition, illumination, and salinity were the main variables associated with microalgal assemblage. Compared with the previous studies, an increase in phytoplankton abundance and change in the dominant species coincided with increased exploitation activities in this bay （e.g. operation of coastal power plants, intensive mariculture, tidal fiat reclamation, and industrial and agricultural development）. The present findings suggest that the government should exercise caution when deciding upon developmental patterns in the sea-related economy.

Comparison of sedimentary organic carbon loading in the Yap Trench and other marine environments

Knowledge about organic carbon loadings(ratio of sedimentary organic carbon(SOC)content to specific surface area(SSA))and the fate of organic carbon(OC)is critical to understand the marine carbon cycle.We investigated the variations in the patterns of OC loadings and the preservation capacities of sedimentary OC in the Yap Trench and other marine environments.The average OC loading in sediment cores from various marine environments decreases with increasing water depth at a rate of^0.06 mg OC/(m^2·km)(R^2=0.23,P<0.01).Distinct low OC loadings(0.09±0.04 mg OC/m^2)were observed in the Yap Trench,with the lowest values as^0.02 mg OC/m^2.A further comparative analysis indicated that OC/SSA=0.2 mg OC/m^2 is a good indicator to distinguish between oxic deep-sea regions and suboxic energetic deltaic areas.Regression analysis between OC loading and bulk carbon isotope compositions indicates that marine OC(δ13C^-20.4‰to-18.6‰)dominates the lost OC within the Yap Trench and does not differ from that of the abyssal zone.In contrast,terrestrial OC withδ13C values of approximately-27.4‰to-20.5‰was the major source of remineralized OC in the sublittoral zone.The ratios of OC loadings in the bottom layer relative to those in the top layers of sediment cores indicate that the preservation capacities of hadal trenches are much lower than those of other environments,and only approximately 30%of the SOC deposited in hadal trenches is finally buried.The value is equivalent to 0.066%of the primary production-derived OC and much lower than the global ocean average(~0.3%).Overall,the hadal zone exhibits the lowest OC loading and preservation capacity of SOC of the different marine environments investigated,despite the occurrence of a notable funneling effect.

Sedimentary records of eutrophication in the Changjiang Estuary upwelling area over last 100 a

The upwelling area in the Changjiang Estuary was selected to collect the core, where the red tide occurred frequently and hypoxic existed. The total organic carbon （TOC）, total nitrogen （TN）, biogenic silica （BSi） and stable organic carbon isotopic ratios（δ13 Corg） were determined on the 210pb-dated sediment core. The concentrations of TOC, TN, BSi as well as their sedimentation fluxes have in- creased to some extent since the 1970s. TOC and TN fluxes increased about 45%, 36% respectively. The average δ13 Coorg value in the core was -23.67 ×10^-3 which remained nearly constant before the 20 century. The δ13 Corg values increased after the 1900s, two marked increases were observed from the 1950s and the 1970s. A simple δ13 Cors model was used to estimate the contribution of terrigenous and marine organic matter inputs for the sediment, which indicated the increase in accumulation since the 1970s has been almost exclusively marine. The increasing of marine organic matter accumulation （TOC, TN and BSi） was corresponding with the increasing of fertilizer consumption and the NO3-N budgets from the Changjiang River. The riverine runoff of fertilizers and nutrients stimulated the algae blooming. Enhanced primary production resulted in an enrichment of organic matter in the sediment. These data support the hypothesis that anthropogenic nutrient loading has been a significant factor on the eutrophication in the Changjiang Estuary.

Calcareous Nannofossils and Molecular Fossils in Cobalt-rich Crusts and their Response to the P/E Global Event

A biostratigraphic study on calcareous nannofossils from the CM3D06 Co-rich ferromanganese crust from the Magellan seamounts in the northwestern Pacific enabled estimation of depositional age. The bio-imprinting of calcareous nannofossils and other fossil species suggests six age ranges for the nannofossils： late Cretaceous, late Paleocene, （early, middle, late） Eocene, middle Miocene, late Pliocene, and Pleistocene. Gas chromatography （GC） and gas chromatography-mass spectrometry （GC-MS） were used to test the Co-rich crusts, and a variety of molecular fossils were detected, such as chloroform bituminous ＂A＂ , n-alkane, isoprenoid and sterol. Peak carbon and molecular indices （such as C23-/C24＋, CPI, Pr/Ph, Pr/nC17, Ph/nCxs and j13C） indicate that the parent organic matter is dominated by marine phytoplankton and thallogen whereas there is little input of terrestrial organic matter. Researches on calcareous nannofossils, molecular fossils and molecular organic geochemistry data reveal that the Paleocene/Eocene （P/E） global event is recorded in the cobalt- rich crusts from the northwestern Pacific Ocean. A succession of biomes can be observed near the 85 mm boundary （about 55 Ma）, i.e., the disappearance of the late Cretaceous Watznaueria barnesae and Zigodicus spiralis, and Broisonia parka microbiotas above the P/E boundary, and the bloom of Coccolithus formosus, Discoaster multiradiatus, Discoaster mohleri and Discoaster sp. below the boundary. Typical parameters of molecular fossils, such as saturated hydrocarbon components and carbon-number maxima, Pr/Ph, Pr/C17, Ph/C18, distribution types of sterols, Ts/Tm ratios and bacterial hopane, also exhibit dramatic changes near the P/E boundary. These integrated results illustrate that the biome succession of calcareous nannofossils, relative content of molecular fossils and molecular indices in the cobalt-rich crusts near the 85 mm boundary faithfully record the P/E global event.

Variations of Summer Phytoplankton Community Related to Environmental Factors in a Macro-Tidal Estuarine Embayment, Hangzhou Bay, China

To explore the distribution and composition of phytoplankton community and their responses to environmental changes, summer net-collected phytoplankton and physicochemical parameters in the Hangzhou Bay during 2004–2010 were investigated. A total of four phyla and 84 species were identified, including 67 diatom and 12 dinoflagellate species. The dominant species con- stantly consisted of the diatoms, although the dominance of dinoflagellate and cyanobacteria increased recently. Due to great spa- tio-temporal variations in environmental factors(salinity, suspended solids, and nutrient concentration), significant heterogeneities in community compositions among different years and subregions(inner and middle sections, and bay mouth) were found based on the analyses of multidimensional scaling and similarity. Canonical correspondence analysis showed that salinity and Si/N were the main variables associated with algal assemblage. Compared with the historical data since the 1980 s, eutrophication(N, P, and N/P increased with decreasing Si/N) was exacerbated drastically. Moreover, climatic forcing and human activities resulted in a series of physical alterations, including sediment retention, temperature increase, and salinity decrease as well as reduction in water exchanges. All these changes induced obvious increases in cell density and Chl-a while decreases in species diversity and diatom-dinoflagellate ratio as well as the shifting of dominant species. Therefore, the long-term phytoplankton variations were closely related to anthropogenic and climatic perturbations in the Hangzhou Bay.

Environmental control of mesozooplankton community structure in the Hangzhou Bay, China

A quarterly study of mesozooplankton community structure and environmental variables in the Hangzhou Bay was conducted to examine the response of mesozooplankton community to the variation of water mass and environmental condition. The southeast coast of China is a typical region under the intensive influence of Asia monsoon and freshwater discharge from rivers. The water mass and environmental condition of the Hangzhou Bay, which were influenced by the interaction of currents, freshwater discharge of the Qiantang River and Changjiang River Plume, showed significant seasonal variation. Our results showed that both biomass and abundance were significantly higher in summer（（247.7±148.8） mg/m^3 and（350.9±215.6） ind./m^3, respectively）than those in other seasons. Four eco-geographical regions were divided based on the cluster analysis of zooplankton community of the Hangzhou Bay throughout the year, except for winter. Monsoon and the dissolved inorganic nitrogen（DIN） input from freshwater discharge of the Qiantang River and Changjiang River resulted in temporal and spatial variations of environmental gradient in the Hangzhou Bay, which significantly influenced the structure of mesozooplankton community. Redundancy analysis（RDA） indicated that the mesozooplankton community structure was strictly correlated with the DIN gradient, while salinity gradient showed a weak influence in the Hangzhou Bay.

Phytoplankton composition and its ecological effect in subsurface cold pool of the northern Bering Sea in summer as revealed by HPLC derived pigment signatures

CHEMTAX analysis of high-performance liquid chromatography （HPLC） pigment was conducted to study phytoplankton community structure in the northern Bering Sea shelf, where a seasonal subsurface cold pool emerges. The results showed that fucoxanthin （Fuco） and chlorophyll a （Chl a） were the most abundant diagnostic pigments, with the integrated water column values ranging from 141 to 2160 μg/m2 and 477 to 5 535 μg/m2, respectively. Moreover, a diatom bloom was identified at Sta. BB06 with the standing stock of Fuco up to 9214 μg/m3. The results of CHEMTAX suggested that the phytoplankton community in the northern Bering Sea shelf was dominated by diatoms and chrysophytes with an average relative contribu- tion to Chl a of 80% and 12%, respectively, followed by chlorophytes, dinoflagellates, and cryptophytes. Dia- toms were the absolutely dominant algae in the subsurface cold pool with a relative contribution exceeding 90%, while the contribution of chrysophytes was generally higher in oligotrophic upper water. Additionally, the presence of a cold pool would tend to favor accumulation of diatom biomass and a bloom that occurred beneath the halocline would be beneficial to organic matter sinks, which suggests that a large part of the phytoplankton biomass would settle to the seabed and support a rich benthic biomass.

Spatial and temporal dynamics of phytoplankton and bacterioplankton biomass in Sanya Bay, northern South China Sea

The composition of phytoplankton and the dynamics of phytoplankton and bacterioplankton biomass （PB and BB, respectively） of Sanya Bay, South China Sea, were determined. A total of 168 species （67 genera） phytoplankton were identified, including BaciUariophyta （diatom, 128 species）, Pyrrophyta （35 species）, Cyanophyta （3 species）, and Chrysophyta （2 species）. Annual average zbundance of phytoplankton was 1.2 × 107 cells/m^3, with the highest abundance in autumn, and the lowest in summer. Annual average diversity index （H＇） and evenness （J） values were 3.96 and 0.70, respectively. Average chlorophyll-a was 2.5 mg/m^3, and the average PB was 124 mg C/m^3, with the highest value in autumn. Surface PB was higher than the bottom, except for summer. Annual mean bacterioplankton abundance and BB were 6.9 × 10^1l cells/m^3 and 13.8 mg C/m^3, respectively. The highest BB was found in summer, followed by winter, spring, and autumn. Surface BB was higher than bottom all year round. The spatial distribution patterns of PB and BB were very similar with the highest biomass in the estuary, and decreased seaward, primarily due to the terrestrial input from the Sanya River and influx of oceanic water. The main factor influencing PB and BB was dissolved inorganic nitrogen （DIN）. Other factors such as temperature, which is above 22℃ throughout the year, had a negligible impact. The correlation between BB and PB was significant （P 〈 0.01）. The annual average ratio of BB/PB was 0.12 （0.06-0.15）. Phytoplankton primary production was one of the most important factors in controlling the distribution of bacterioplankton.

The partial pressure of carbon dioxide and air-sea fluxes in the Changjiang River Estuary and adjacent Hangzhou Bay

The distributions of partial pressure of carbon dioxide （pCO2） in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095/zatm （1 atm=101 325 Pa） in the inner estuary, 177-1 036/zatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/（m2.d） [61 mmol/（m2.d） on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.

Composition of algal pigments in surface freshen layer after ice melt in the central Arctic

Seasonal meltwater input creates a thin freshen layer in surface seawater under ice, which largely shifts the algae assemblages. Our recent observation of photosynthetic pigments in the high Arctic showed that ice bottom and 5 m of seawater under ice contained relatively high concentration of fucoxanthin, while chlorophyll b and lutein were the major diagnostic pigments in ice-water interface and 0 m of seawater under ice. Additionally, a notable change of dominant phytoplankton occurred in the top 5 m of seawater under ice, from chlorophytes-dominated at surface to diatoms-dominated at 5 m depth, which might attribute to the sharp salinity gradient （salinity from 12.5 to 28.1） in the surface seawater under ice. Our results imply that phytoplankton community in surface layer under ice would become more chlorophytes in the future warming Arctic Ocean.

Variations in organic carbon loading of surface sediments from the shelf to the slope of the Chukchi Sea,Arctic Ocean

The content of organic carbon （OC） normalized to the specific surface area （SSA） of sediment is widely used to trace variations in OC loading （OC/SSA）. This study presents observations of OC/SSA of surface sediments collected in the Chukchi Sea, a typical Arctic marginal sea. Shelf sediments exhibit much higher OC/SSA values than slope sediments in the study area. Compared with OC/SSA values reported from the East Siberian Shelf and Mackenzie River, the slope sediments possess lower OC loading. This abrupt decrease in OC/SSA is mostly related to the lower primary production on slope as well as possible oxidization processes. The results of linear regression analysis between OC and SSA indicate a sedimentary source rock for the OC in the Chukchi Sea sediments. Moreover, shelf sediments with low SSA possess a larger rock OC fraction than slope sediments do. The dataset of the present study enables a more thorough understanding of regional OC cycling in the Chukchi Sea.

Macrobenthic assemblages of the Changjiang River estuary (Yangtze River, China) and adjacent continental shelf relative to mild summer hypoxia

To assess the effects of hypoxia, macrobenthic communities along an estuarine gradient of the Changjiang estuary and adjacent continental shelf were analyzed. This revealed spatial variations in the communities and relationships with environmental variables during periods of reduced dissolved oxygen （DO） concentration in summer. Statistical analyses revealed significant differences in macrobenthic community composition among the three zones： estuarine zone （EZ）, mildly hypoxic zone （MHZ） in the continental shelf, and norrnoxic zone （NZ） in the continental shelf（Global R=0.206, P=0.002）. Pairwise tests showed that the macrobenthic community composition of the EZ was significantly different from the MHZ （pairwise test R=0.305, P=0.001） and the NZ （pairwise test R=0.259, P=-0.001）. There was no significant difference in macrobenthic communities between the MHZ and the NZ （pairwise test R=0.062, P=-0.114）. The taxa included small and typically opportunistic polychaetes, which made the greatest contribution to the dissimilarity between the zones. The effects of mild hypoxia on the macrobenthic communities are a result not only of reduced DO concentration but also of differences in environmental variables such as temperature, salinity, and nutrient concentrations caused by stratification.

New discovery of seafloor hydrothermal activity on the Indian Ocean Carlsberg Ridge and Southern North Atlantic Ridge-progress during the 26th Chinese COMRA cruise

The 26th Chinese COMRA （China Ocean Mineral Resources Research ＆ Development Association） cruise was an important cruise. The Carlsberg Ridge （CR） of the Northwest Indian Ocean and the North Atlantic Ridge （NAR）, in which less investigation has been carried out for hydrothermal activities, were investigated and studied during the first two legs of the 26th COMRA cruise. During the first leg, we found one hydrother- mal activity field located in the CR at 3.5^-3.8~ N on the Northwest Indian Ocean Ridge （NWIR）, and sampled seafloor polymetallic sulfide deposits where only abnormalities were found before. During the second leg, we found a new hydrothermal anomaly field located in the NAR at 4^-7~N. The discovery of two hydrother- real and anomaly fields filled in the gap of hydrothermal investigation and study in the corresponding re- ~ions for China.

Bacterial diversity and community structure in the East China Sea by 454 sequencing of the 16S rRNA gene

The 454 sequencing method was used to detect bacterial diversity and community structure in the East China Sea. Overall, 149 067 optimized reads with an average length of 454 nucleotides were obtained from 17 seawater samples and fi ve sediment samples sourced in May 2011. A total of 22 phyla, 34 classes, 74 orders, 146 families, and 333 genera were identifi ed in this study. Some of them were detected for the fi rst time from the East China Sea. The estimated richness and diversity indices were both higher in the sediment samples compared with in the seawater samples. All the samples were divided by their diversity indices into four regions. Similarity analysis showed that the seawater samples could be classifi ed into six groups. The groups differed from each other and had unique community structure characteristics. It was found that different water masses in the sampling areas may have had some infl uence on the bacterial community structure. A canonical correspondence analysis revealed that seawater samples in different areas and at different depths were affected by different environmental parameters. This study will lay the foundation for future research on microbiology in the East China Sea.

Grain size composition and transport of sedimentary organic carbon in the Changjiang River(Yangtze River) Estuary and Hangzhou Bay and their adjacent waters

Surface sediments from the Changjiang River （Yangtze River） Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon （OC） concentration, and stable carbon isotope composition （δ13C）. Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand （〉0.250 ram, 0.125-0.250 ram, 0.063-0.125 mm） and silt （0.025-0.063 mm） fractions by wet-sieving fractionation methods, and further into silt- （0.004-0.025 mm） and clay-sized （〈0.004 mm） fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and 613C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28%0, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions （〈0.025 ram） was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways： one was a result of the Changjiang River Diluted Water （CDW） northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.

Different vertical distribution of zooplankton community between North Pacific Subtropical Gyre and Western Pacific Warm Pool: its implication to carbon flux

The mesozooplankton in both epipelagic and mesopelagic zones is essentially important for the study of ecosystem and biological carbon pump. Previous studies showed that the diel vertical migration (DVM) pattern of mesozooplankton varied among ecosystems. However, that pattern was largely unknown in the Western Pacific Warm Pool (WPWP). The vertical distribution, DVM and community structure of mesozooplankton from the surface to 1 000 m were compared at Stas JL7K (WPWP) and MA (North Pacific Subtropical Gyre, NPSG). Two sites showed similarly low biomass in both epipelagic and mesopelagic zones, which were in accordance with oligotrophic conditions of these two ecosystems. Stronger DVM (night/day ratio) was found at JL7K (1.31) than that at MA (1.09) on surface 0–100 m, and an obvious night increase of mesopelagic biomass was observed at JL7K, which was probably due to migrators from bathypelagic zone. Active carbon flux by DVM of zooplankton was estimated to be 0.23 mmol/(m2·d) at JL7K and 0.16 mmol/(m2·d) at MA. The community structure analysis showed that calanoid copepods, cnidarians and appendicularians were the main contributors to DVM of mesozooplankton at both sites. We also compared the present result with previous studies of the two ecosystems, and suggested that the DVM of mesozooplankton was more homogeneous within the WPWP and more variable within the NPSG, though both ecosystems showed typically extremely oligotrophic conditions. The different diel vertical migration strength of mesozooplankton between NPSG and WPWP implied different efficiency of carbon pump in these two ecosystems.

Spatial and temporal variability and size fractionation of chlorophyll a in the tropical and subtropical Pacific Ocean

The spatial and temporal variability and size fractionation of chlorophyll a (Chl a) were investigated in the tropical and subtropical Pacific Ocean during four survey cruises from 2005 to 2009.The surface Chl a (S-Chl a) concentration ranged from 0.002 to 0.497 mg/m3 and was obviously higher in the eastern Pacific than in the western and central Pacific.The vertical distribution of Chl a displayed a single peak pattern,and the maximum Chl a layer (MCL) was observed at a shallower depth in the eastern Pacific than in the western Pacific.All three size fractions of Chl a measurements in the surface water showed a similar distribution to total Chl a and were found in higher concentrations in the eastern Pacific than in the western and central Pacific.Picoplankton dominated the phytoplankton in the surveyed tropical and subtropical Pacific Ocean.Furthermore,pico-Chl a (0.2-2 μm) accounted for a larger percentage of the total Chl a in the central Pacific than it did in the western Pacific and eastern Pacific.In the western Pacific,there seemed to be a latitudinal variability in the phytoplankton community composition where small-sized phytoplankton (＜2 μm) were more dominant in the tropical than in the subtropical western Pacific.The spatial and temporal variability and size fractionation of Chl a were controlled by hydrological and chemical characteristics and climate events,such as El Ni(n)o and La Ni(n)a.

Biomineralization of organic matter in cobalt-rich crusts from the Marcus–Wake Seamounts of the western Pacific Ocean

Organic matter in cobalt-rich crust （CRC） from the Marcus-Wake Seamounts of the western Pacific Ocean, Sample CM1D03, has been analyzed to understand the source, geochemistry and mineralization of organic matter, and the mineralization environment. Biomarkers, includingn-alkanes, isoprenoids, terpanes and sterols, have been detected in various layers of the CRC sample, using gas chromatography （GC） and gas chromatography-mass spectrometry （GC-MS）. The content of organic carbon （OC） and its stable isotope （δ13C）, and the combined features of the biomarkers show that the mineralized organic matter in CM1D03 CRC was mainly derived from microorganisms and lower plankton （e.g., bacteria and algae, respectively） from marine surface water, with some terrestrial higher plant components. The ratio of chloroform bitu-men ＂A＂： OC was high in the CRC, between 10.51 and 20.66, showing significant migration characteristics of n-alkanes. Four mineralization categories of organic matter were recognized based on GC chromatograms ofn-alkane molecules： （1） primitive type （bacteria and algae）, which is characterized by moderately mature ofn-alkanes preserving the original characteristics of the organic matter from microorganisms and lower plankton; （2） microbial degradation type, which is characterized by low contents ofn-alkanes and rising baseline in the chromatogram, with the ＂bulge＂ being the products of organic matter by biodegradation; （3） organic matter migration type, which is characterized by low carbon number ofn-alkanes withnC18 as the main peak carbon, without odd even predominance, and low concentrations of isoprenoids and hydro-carbons with high carbon number; and （4） organic matter hydrothermal type, which is characterized by relatively low concentration of small molecular weightn-alkanes, pristane, and phytane, accompanied by higher concentration ofn-alkanes with carbon number greater thannC18. This study shows that biomarkers can record controlling factors of mineralization and their variation.

Catalogue of Polychaete species(Annelida) described from China Seas during 2008–2017

China Seas are one of the most diverse regions in the Pacific. Though much eff ort has been made to explore its biodiversity, the polychaetes diversity is still poorly known. A large number of species records are based on ecological investigation rather than taxonomical studies. We update the Polychaete species taxonomicaly described from China coastal waters during 2008–2017 and list them as a catalogue. The catalogue contains 47 species of 32 genera and 17 families, the type depository, type locality and geographic distribution. Some taxonomic problems are present in remarks.

Morphological and genetic comparison of two strains of a Prorocentrum species isolated from Zhejiang coastal water of China and Masan Bay of Korea

In this paper, we examined the detailed morphology of two strains of Prorocentrum isolated from the coastal waters of Zhejiang (Wenling area), China, and Masan Bay of Korea. A taxonomic comparison was made among strains on the basis of morphological and molecular data. The cellular dimensions of the Chinese Wenling strain (LAMB090508) and Korean strain (PDKS0206) were similar and the cells of both strains were of asymmetric and elongated shape. The posterior end of most cells was rounded. Megacytic zones of aged cells were broader with dense tiny knobs. The roundish nucleus was located in the posterior part of the cell. A few irregular shaped chloroplasts were distributed within the cell. The nucleotide similarity of the two strains, determined from the 5.8S rDNA-ITS sequences, was 99.83%. The comparative results of morphology and molecular analysis suggest that both strains isolated from China and Korea were the identical species, Prorocentrum donghaiense Lu.