Coastal East China Sea Research Articles

Decadal variations in diatoms and dinoflagellates on the inner shelf of the East China Sea, China

Diatoms and dinoflagellates are two major groups of phytoplankton that flourish in the oceans, particularly in coastal zone and upwelling systems, and their contrasting production have been reported in several world seas. However, this information is not available in the coastal East China Sea (ECS). Thus, to investigate and compare the decadal trends in diatoms and dinoflagellates, a sediment core, 47 cm long, was collected from the coastal zone of the ECS. Sediment chlorophyll-a (Chl-a), phytoplankton-group specific pigment signatures of diatoms and dinoflagellates, and diatom valve concentrations were determined. The sediment core covered the period from 1961 to 2011 AD. The chlorophyll-a contents ranged from 2.32 to 73 µg/g dry sediment (dw) and averaged 9.81 µg/g dw. Diatom absolute abundance ranged from 29152 to 177501 valve/gram (v/g) dw and averaged 72137 v/g dw. Diatom valve and diatom specific pigment marker concentrations were not significantly correlated. Peridinin increased after the 1980s in line with intensified use of fertilizer and related increases in nutrient inputs into the marine environment. The increased occurrence of dinoflagellate dominance after the 1980s can be mostly explained by the increase in nutrients. However, the contribution of dinoflagellates to total phytoplankton production (Chl-a) decreased during the final decade of this study, probably because of the overwhelming increase in diatom production that corresponded with the construction of the Three Gorges Dam (TGD) and related light availability. Similarly, the mean ratio of fucoxanthin/peridinin for the period from 1982 to 2001 was 6% less than for 1961 to 1982, while the ratio for 2001 to 2011 was 45.3% greater than for 1982 to 2001. The decadal variation in the fucoxanthin/peridinin ratio implies that dinoflagellate production had been gradually increasing until 2001. We suggest that the observed changes can be explained by anthropogenic impacts, such as nutrient loading and dam construction.

Longshore suspended sediment transport and its implications for submarine erosion off the Yangtze River Estuary

Coastal currents that originate from large rivers play a key role in delivering sediment to shelf regions. Quantifying their transport capability is therefore essential to understanding the sediment budgets and the consequent deposition or erosion of coastal areas. In February 2012, we observed the sediment transport carried by the Min-Zhe Coastal Current that originates from the Yangtze River mouth and calculated a flux of 18.7 tons per second on a cross-shore section. In this period the coastal current was at a typical status, which allowed us to estimate a total annual sediment transport of 0.27billion tons southward. This result was more than three times the present annual Yangtze River sediment discharge, suggesting that considerable net sediment removal occurs in the coastal regions. The sediment transport 0.27 billion tons/year is probably the deposition/erosion threshold for the East China Sea coast north of our study site. Analysis of historical Yangtze River sediment influx records showed, that the onset and acceleration of coastal erosion was closely linked with the operation of the Three Gorges Dam (TGD) upstream of the Yangtze River.

Comparison of PM2.5 carbonaceous pollutants between an urban site in Shanghai and a background site in a coastal East China Sea island in summer: concentration, composition and sources.

Nine paired samples of atmospheric particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5) were collected concurrently from an urban site in Shanghai, China and a background site in Huaniao Island (HNI) in the coastal East China Sea (ECS) between July 21 and 29, 2011. The samples were analyzed for 16 United States Environmental Protection Agency (USEPA) priority polycyclic aromatic hydrocarbons (PAHs), n-alkanes (20 species, C14-C33), hopanes (10 species, C29-C32), and steranes (12 species, C27-C29). These two sites, approximately 66 km apart, are both on the pathway of land-based pollutants as they are transported to the ECS by seasonal winds. As expected, concentrations in Shanghai were higher (average: 8.4 and 67.8 ng m-3 for the 16 PAHs and n-alkanes, respectively) than those in HNI (average: 1.8 and 8.5 ng m-3, respectively). The dominant contributor to the 16 PAHs in Shanghai was 5-6-ring PAHs (60.0%), whereas 2-3-ring PAHs contributed the most (72.5%) in HNI. Plant waxes contributed 45.7% and 25.9% of the n-alkanes in Shanghai and HNI, respectively, implying a relatively greater contribution from petroleum residues to the n-alkanes in HNI. Principal component analysis (PCA) and the compositions of hopanes and steranes highlighted a prominent contribution from traffic emissions to carbonaceous PM2.5 aerosols. This study provides comprehensive details about the sources, formation, and transport of pollutants from eastern China to the coastal ECS.

Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan

ABSTRACTTo complement previous studies on the diversity of cheilostome bryozoans (Bryozoa: Gymnolaemata: Cheilostomata) in the rocky-intertidal habitat in the North Pacific, we sampled rocky substrata at three sites on the subtropical East China Sea coast of Okinawa, Japan (26°N). We examined 651 colonies or colony fragments by light microscopy or scanning electron microscopy (SEM). The range in single-site richness was 16–36 species, with 52 species detected overall. We provide descriptions and illustrations for all species, including 11 (21.2%) new species (Thalamoporella karesansui, Crassimarginatella eremitica, Hippothoa petrophila, Stephanotheca fenestricella, Calyptotheca sesokoensis, Fenestrulina parviporus, Arthropoma harmelini, Rhynchozoon maculosum, Rhynchozoon lunifrons, Rhynchozoon ryukyuense, and Rhynchozoon scimitar) and 34 (65.4%) new records for Japan. Species were patchy in local distribution, with 53.8% detected at only one among the three sites, and often rare, with 34.6% represented by only one or two specimens. Most species (94.2%) were encrusting, forming two-dimensional, sheet-like colonies or (in two cases) branching uniserial networks; three species formed small, recumbent colonies. Ascophoran-grade species (82.7%) outnumbered anascan-grade species (17.3%). Biogeographically the fauna we examined is characteristic of the Central Indo-Pacific (CIP) realm of Spalding et al.: among 40 previously described species with distributions known outside the study area, 36 (90.0%) occur in the CIP realm, and 11 (27.5%) are restricted to it. In contrast, only seven species (17.5%) have been reported from the Temperate Northern Pacific realm, including two putatively cosmopolitan species. The high proportion (86.5%) of new records for Japan (including the new species) suggests that the marine bryozoan fauna in far-southern Japan remains largely unexplored. Given that many species were rare or uncommon in the study area and/or patchily distributed among the three sites, further sampling at additional intertidal sites in the Sesoko area will likely detect higher total local richness than the 52 species we found.http://www.zoobank/urn:lsid:zoobank.org:pub:9FD78C14-60AA-44A9-A9A2-3258E5770D31

Seasonal and Interannual Variability in the Wind-Driven Upwelling Along the Southern East China Sea Coast

The southern East China Sea coast (ECSC) is strongly influenced by the eastern Asian monsoon. During the summer when the southerly monsoon dominates, coastal upwelling is favored. This paper applies a coastal upwelling index (CUI) proposed by Bakun to quantify the upwelling intensity. Using observed sea surface wind and chlorophyll concentration (Chlc) data, we examine the seasonal and interannual variations of the upwelling in the ECSC, as well as its spatial distribution. The high correlation between the CUI and Chlc indicates the validation of the CUI. The temporal variation is linked to the basin-scale variation—the El Nino southern oscillation (ENSO) and pacific decadal oscillation (PDO)—to interpret its long-term variation. A high eddy kinetic energy (EKE) band is coincidently located at the upwelling front along the ECSC, which implies that the mixing caused by frontal instabilities could further modulate the Chlc.

Distribution and region-specific sources of Dechlorane Plus in marine sediments from the coastal East China Sea

Dechlorane Plus (DP) is a highly chlorinated flame retardant and found to be ubiquitously present in the environment. We reported here the first record of DP in sediments from the coastal East China Sea (ECS). DP was detected in most of the surface sediments, and the concentrations ranged from 14.8 to 198pg/g dry weight (dw) with a mean value of 64.4pg/g dw. Overall, DP levels exhibited a seaward decreasing trend from the inshore toward outer sea. The fractional abundance of anti-DP (fanti) showed regional discrepancies, attributing to different environmental behaviors of DP isomers. Depth profiles of DP in a sediment core from estuarine environment showed distinct fluctuation, and the core in open sea had stable deposition environment with two peak values of DP in ~1978 and 2000. The fanti exhibited downward decreasing trend prior to mid-1950s, indicating a preferential degradation of anti-DP and/or a greater adsorption capacity of syn-DP after its burial. Lignin and lipid biomarkers (∑C27+C29+C31n-alkanes) of terrestrial organic matters were introduced to identify region-specific sources of DP, and the results showed that DP in the northern inner shelf, southern inner shelf of 29 °N and mud area southwest of Cheju Island was mainly come from Yangtze River (YR) input, surface runoffs after discharge of local sources close to the Taizhou-Wenzhou Region and the atmospheric deposition from the North China and East Asia, respectively. The coastal ECS was an important reservoir of DP in the world, with mass inventory of approximately 310.7kg in the surface sediments (0–5cm).

Characterizing distributions, composition profiles, sources and potential health risk of polybrominated diphenyl ethers (PBDEs) in the coastal sediments from East China Sea

Sediment samples (n = 20) were collected from Yangtze River Estuary (YRE) and the adjacent East China Sea (ECS) inner shelf to explore spatial and temporal distributions, environmental fate, sources and potential health risk of polybrominated diphenyl ethers (PBDEs). Concentrations of BDE-209 and total 7 PBDEs (without BDE-209; ∑7PBDEs) ranged from 62.3 to 1758 pg g−1 and from 36.9 to 233.6 pg g−1 dry weight, respectively; both of the highest values occurred near the city of Wenzhou. Concentrations of BDE-209 and ∑7PBDEs both indicated a decreasing trend from inshore areas toward outer shelf. Significantly positive linear correlations were only observed between logBDE-183 concentrations and TOC/grain size (r2 = 0.6734 and 0.5977 for TOC and grain size, respectively) as well as BDE-209 and TOC/grain size (r2 = 0.4137 and 0.5332 for TOC and grain size, respectively) in the north of 28°N, indicating that YR had significant influence on the distribution of higher brominated congeners only in the north part. Depth profiles of PBDEs in a sediment core P01 (n = 1, m = 11) collected from YRE showed that the input of BDE-209 gradually increased from 1930 to 2010, while the levels of ∑7PBDEs peaked in 1986 and obviously decreased in recent years. Partial Least-Squares Regression (PLSR) revealed that PBDEs in the coastal ECS were mainly from direct discharge of local anthropogenic activities (80.7%), followed by surface runoff of contaminated soils (15.1%), microbial degradation after sedimentation (2.6%) and photodegradation during atmospheric transportation (1.6%). The cancer risk of human exposure to BDE-209 at the 95% confidence level was 3.09 × 10−7, 1.67 × 10−7 and 8.86 × 10−7 for children, teens and adults, respectively, significantly lower than the threshold level (10−6). Hazard index (HI) calculated for non-cancer risk was also far less than 1 for the three groups, suggesting no non-cancer risk.

The impact of atmospheric deposition of cadmium on dominant algal species in the East China Sea

Cadmium (Cd) mainly derived from anthropogenic emissions can be transported through atmospheric pathway to marine ecosystem, affecting the phytoplankton community and primary productivity. In this study, we identified the toxicity threshold of Cd for phytoplankton under seawater conditions of the coastal East China Sea (ECS) through both laboratory and in situ mesocosm incubation experiments. The mesocosm experiment showed that Cd in low concentration (0.003 μg per μg chl a) was conducive to the growth of natural community and increased chl a productivity. In high concentration (0.03 μg per μg chl a) Cd acted as an inhibiting factor which decreased the total chl a productivity. The diatom community was found to be more sensitive to Cd toxicity than dinoflagellate, as the low concentration Cd showed toxicity to diatom but enhanced dinoflagellate growth. We noticed that the soluble Cd estimated from atmosphere deposition to the coastal ECS was below the toxicity threshold and the Cd deposition might promote phytoplankton growth in this region. In our laboratory experiments, adding Cd, similar to aerosol deposition, stimulated the growth of both dominant algal species Prorocentrum donghaiense Lu (dinoflagellate) and Skeletonema costatum (diatom). Adding Cd on a higher level inhibited the growth of both the species, but Skeletonema costatum seemed obviously more sensitive to toxicity. This indicates the potential impact of atmospheric deposition Cd on phytoplankton community succession in the ECS.

Phytoplankton community diversity is influenced by environmental factors in the coastal East China Sea

Surface seawater was collected in four different seasons in the coastal East China Sea adjacent to the Yangtze River Estuary and phytoplankton community diversity was analysed using rbcL genetic markers. Phytoplankton diversity (Shannon Index) was found to be highest in autumn and lowest in summer, which was mainly controlled by seawater temperature, river runoff, the Taiwan Warm Current and possibly other environmental factors. For taxa characterized by Form IAB rbcL, the abundance of Chlorophyta was much greater than those of Proteobacteria and Cyanobacteria throughout the year with the most dominant taxa being Bathycoccus prasinos (Chlorophyta) in spring and Micromonas sp. (Chlorophyta) in other seasons. For taxa identified by Form ID rbcL, Coscinodiscophyceae (diatoms) constituted the largest group (most clones) in the phylogenetic tree. Dinophysis fortii (a dinoflagellate) was found to be the most abundant species in winter and spring and Skeletonema spp. (a diatom) dominated the phytoplankton community in summer and autumn. The seasonal dominance of Dinophysis fortii agreed well with the recently increasing proportion of dinoflagellates in the phytoplankton community in the coastal East China Sea. The abundance of Dinophysis fortii was negatively correlated with seawater temperature, suggesting that harmful algal blooms caused by this species may primarily occur in spring.

DDTs and HCHs in sediment cores from the coastal East China Sea

Four sediment cores were collected along the Yangtze-derived sediment transport pathway in the inner shelf of the East China Sea (ECS) for OCP analysis. The sediment records of HCHs and DDTs in estuarine environment reflected remobilization of chemicals from enhanced soil erosion associated to extreme flood events or large scale land use transformation. The sediment records in the open sea, instead, reflected long-term historical trends of OCP application in the source region. Unlike the so-called mud wedge distribution of sediment, inventories of HCHs and DDTs slightly increased from the mouth of Yangtze River alongshore toward south, suggesting the sediment deposition rate was one of factors on the exposure of chemicals within the inner shelf of the ECS. Re-suspension and transport of the Yangtze-derived sediment and consequent fractionation in grain size and TOC were also responsible for the spatial variation of inventories of catchment derived OCPs in a major repository area of the Yangtze suspended sediment. The total burdens of HCHs and DDTs in the inner shelf of the ECS were 35tons and 110tons, respectively. After 1983 (year of the official ban in China), those values were 13tons and 50tons, respectively. It appears that the Yangtze still delivers relatively high inputs of DDTs more than 30years after the official ban. High proportions of DDD+DDE and β-HCH suggested those OCPs mainly originated from historical usage in the catchment recent years.

Air-Seawater Exchange of Organochlorine Pesticides along the Sediment Plume of a Large Contaminated River.

Gaseous exchange fluxes of organochlorine pesticides (OCPs) across the air-water interface of the coastal East China Sea were determined in order to assess whether the contaminated plume of the Yangtze River could be an important regional source of OCPs to the atmosphere. Hexachlorocyclohexanes (HCHs), chlordane compounds (CHLs), and dichlorodiphenyltrichloroethanes (DDTs) were the most frequently detected OCPs in air and water. Air-water exchange was mainly characterized by net volatilization for all measured OCPs. The net gaseous exchange flux ranged 10-240 ng/(m2·day) for γ-HCH, 60-370 ng/(m2·day) for trans-CHL, 97-410 ng/(m2·day) for cis-CHL, and ∼0 (e.g., equilibrium) to 490 ng/(m2·day) for p,p'-DDE. We found that the plume of the large contaminated river can serve as a significant regional secondary atmospheric source of legacy contaminants released in the catchment. In particular, the sediment plume represented the relevant source of DDT compounds (especially p,p'-DDE) sustaining net degassing when clean air masses from the open ocean reached the plume area. In contrast, a mass balance showed that, for HCHs, contaminated river discharge (water and sediment) plumes were capable of sustaining volatilization throughout the year. These results demonstrate the inconsistencies in the fate of HCHs and DDTs in this large estuarine system with declining primary sources.

Fluorescence measured using a field-portable laser fluorometer as a proxy for CDOM absorption

The colored fraction of dissolved organic matter, CDOM, directly influences water optical properties and spectral quality, playing an important role in aquatic ecosystems, optical remote sensing and carbon circulation in the sea. Measuring in situ CDOM absorption coefficient, however, is difficult because it requires prefiltration of water samples. A field-portable laser fluorometer for fast acquisition of in situ CDOM fluorescence data without sample filtering was developed. Using the instrument in the Yangtze River estuary, the East China Sea coast, the West Lake, and the Qiandao Lake, good estimates of CDOM absorption were obtained from in situ fluorescence measurements. High correlation (r = 0.94) was observed between CDOM absorption coefficient and fluorescence normalized to Raman scattering in diverse water types. Comparison of different methods for measuring CDOM fluorescence was carried out. Fluorescence measured by in situ laser fluorometer compared very well to the values obtained using more sophisticated laboratory spectrophotofluorometer; a significant relationship (r = 0.95) was identified between the two methods. Spatial distributions of CDOM in the Yangtze River estuary and its adjacent sea compiled from discrete samples analyses were presented. A linear relationship was identified between CDOM fluorescence and salinity in surface water, reflecting the potential of CDOM fluorescence to be used as a passive tracer of freshwater input. The in situ measurement results demonstrated the utility of the laser fluorometer for rapid acquisition of high-resolution profiles, and that the work resulting from sample filtration or storage can be avoided.

Enrichment of heavy metals in the inner shelf mud of the East China Sea and its indication to human activity

The Yangtze River Basin, which has a population of 0.4 billion and an economic output accounting for 50% of China׳s Gross Domestic Product (GDP), is one of the most developed regions in China. With dramatic developments in the economy, large quantities of pollutants have entered the Yangtze River and have eventually been discharged into the East China Sea (ECS), and then most of them were preserved in the inner shelf coastal mud areas of the ECS. The inner shelf costal mud areas of the ECS, with sedimentation rate ranging from 0.8cm/a to 1.2cm/a, are an ideal place to obtain the high-resolution heavy metal record. In this work, two sediment cores collected in the inner shelf of the coastal mud areas of the ECS in 2009 were used to reconstruct historical records of anthropogenic heavy metal input from the Yangtze River Basin. The temporal distribution of enrichment factors (EFs) is in good accordance with social development of Yangtze River Basin. Before the 1930s, the EFs of Pb and Zn are considered as the background level of study area, according to the agricultural country of China in that time. The much higher EFs of Pb and Zn from the 1930s to 1980s were associated with significant improvement of industry of the Yangtze River Basin. After 1983, the dramatical incensement of EFs of Pb and Zn responded to the remarkable economic development of the Yangtze River Basin. Of particular interest, the construction of the Three Gorges Dam (TGD) in 2003 possibly induced a significant increase in the heavy metal levels in the coastal ECS, and the ban on leaded gasoline in China induced a remarkable decrease in Pb levels. Although heavy metal levels have increased since the 1930s, the coastal mud area of the ECS remains under low ecological risk.

SUMMER ASSEMBLAGES OF ICHTHYOPLANKTON IN THE WATERS OF THE EAST CHINA SEA SHELF AND AROUND TAIWAN IN 2007

This study investigated the relationships between assemblages of larval fish and hydrographic features in the East China Sea (ECS) and seas surrounding Taiwan during the summer of 2007. A survey was conducted from 2007 July 1 to 2007 July 11 in the ECS and from 2007 July 4 to 2007 July 16 in the waters surrounding Taiwan. A total of 12,670 larval fishes belonging to 95 families, 163 genes, and 189 species were identified. Engraulis japonicus and Sillago japonica were the 2 dominant species, accounting for 56.15% and 6.66% of the fish larvae samples. The cluster analysis results showed that the fish larval distribution patterns corresponded to hydrographic conditions. The results were also used to identify the following larval assemblages: the Kuroshio assemblage, coastal assemblage, Changjiang diluted water (CDW) / Yellow Sea mixed water assemblage, and Taiwan Strait water assemblage. The spatial distribution results showed a clear association between high abundances of larval fishes and shallow water areas near the ECS coast, and between low abundances and offshore Kuroshio water. The canonical correlation analysis results indicated that abundances of E. japonicus and S. japonica were strongly and positively correlated with chlorophyll a, but negatively correlated with salinity. These associations suggest that food sources and CDW might be crucial factors that determine the abundance and distribution of larval fishes during the summer.

Validation of semi-analytical inversion models for inherent optical properties from ocean color in coastal Yellow Sea and East China Sea

The performances of three semi-analytical retrieval models for water inherent optical properties were validated in the coastal Yellow Sea and East China Sea, including the Quasi-Analytical Algorithm (QAA), the Garver-Siegel-Maritorena model (GSM) and the Over Constrained Linear Matrix (LM). The model-retrieved parameters, namely absorption coefficients of phytoplankton (a ph), colored dissolved and detrital particulate matter (a dg), total absorption coefficients (a t), and backscattering coefficient of particles (b bp), were compared. The bio-optical datasets collected from a Yellow Sea and East China Sea cruise in April and September 2003 were used in the study. The QAA model performed the best in retrieval for all the coefficients, showing log-transformed root mean square errors of 0.306 for a ph, 0.268 for a dg, 0.144 for a t, and 0.273 for b bp at 443 nm. The LM model showed a slightly larger deviation than the QAA model with a similar error trend for absorption coefficients, but it returned the largest uncertainties for b bp, with log-transformed root mean square error up to 0.646. The GSM model, however, yielded the largest and fluctuating errors along with wavelength for absorption coefficient retrievals. Substituting the fitting parameters from measured data for the empirical spectral parameters, all three models returned better results. These improvements demonstrated that semi-analytical algorithms designed for ocean water need regional modifications before applying to coastal areas. The QAA algorithm may be the most suitable model for retrieval for the Yellow Sea and East China Sea, and future model refinements should concentrate on regional modeling of inherent optical properties.

Characteristics of the 2011 Tohoku Tsunami Waveform Acquired Around Japan by Nowphas Equipment

The 2011 Tohoku Tsunami was observed around Japan by NOWPHAS equipment. These devices include GPS buoys which measure water surface levels by real-time kinematic GPS technology and which are moored at sites 10 km to 20 km offshore where water depths range from 100 m to 400 m, seabed wave gauges at depths between 20 m and 60 m, and coastal tide gauges. A GPS buoy moored offshore of Kamaishi Port recorded the first tsunami crest, which rose in two steps and exceeded 6 m approximately 30 min after the earthquake. Data from some sets comprising GPS buoys, nearby seabed wave gauges, and coastal tide gauges determined the extent of the tsunami propagation and amplification on the coast. Resonance caused by the tsunami continued a day or more after the initial tsunami arrival in some stations. A Doppler-type wave directional meter located in the Tokyo Bay entrance acquired data on the vertically uniform distribution of the tsunami current traveling in and out the bay. The tsunami was detected at almost all of the tide gauges around Japan, even in the semi-closed Ariake and Yatsushiro Bays located on the East China Sea coast of the Kyushu region.

Molecular phylogenetic relationship between Trichiurus margarites Li, 1992 and Trichiurus sp.2 (sensu Nakabo, 2002) (Perciformes: Trichi-uridae) based on mitochondrial 16S rRNA sequence analysis

The taxonomic identification of the genus Trichiurus(Trichiuridae) has historically been challenging because of the morphological similarities between the species.As a result,Trichiurus lepturus Linnaeus,1758 was recognized as a monotypic cosmopolitan species of Trichiurus prior to 1990.In 1992,Li proposed the new species T.margarites Li,1992,based on morphological differences in the skull patterns and dorsal fin coloration,i.e.su-praoccipital bone with a hard knob and yellow dorsal fin respectively.Subsequently,Yamada et al.described a species of Trichiurus with a yellow dorsal fin from the Ryukyu Islands and East China Sea coast of Kyushu,Japan.This species is very similar to T.margarites,but shows some variation in the size of a pair of knobs on the su-praoccipital crest.Accordingly,the yellow dorsal fin species of Trichiurus from Japan was provisionally called Trichiurus sp.2 by Nakabo.There remains no molecular evidence that elucidates the genetic differences between T.margarites and T.sp.2(sensu Nakabo,2002).Thus,the phylogenetic relationship and taxonomic status of these two species remain unresolved. In this study we examined the mitochondrial 16S rRNA gene sequence from 11 T.margarites individuals collected from the coast of western Hainan Island(Baimajing,Yinggehai and Sanya),South China Sea,China which is the type locality of T.margarites.The 16S rRNA genes were amplified using PCR techniques.Homolo-gous sequences from T.sp.2 and closely-related species from previous studies were also included in the compara-tive analysis.Genetic information indexes,including base composition,sequence variation,and Kimura-2 pa-rameter net genetic distance were examined.Phylogenetic analysis using neighbor-joining(NJ) and maxi-mum-likelihood(ML) methods were conducted using Eupleurogrammus muticus as the outgroup. There was evidence of insertion or deletion of base pairs in the 435 bp sequence alignment,with 63 variable sites,48 parsimony informative sites,and 15 singleton sites.The net genetic distances between T.margarites(from western Hainan Island) and T.sp.2(from Japan,eastern Hainan Island,and Indian Ocean) ranged from 0.000 to 0.006.These values were much lower than those found for interspecific 16S rRNA comparisons in some species of Trichiurus(0.037–0.061),and for intraspecies comparisons between populations of T.lepturus(0.010–0.016).Moreover,the haplotypes of T.margarites and T.sp.2 did not form reciprocal monophyletic clades in the phylogenetic trees(NJ,ML),and the close relationship of the haplotypes of these two species was supported by high confidence levels(NJ 100%,ML 99%).These results indicated that the genetic distance between T.mar-garites and T.sp.2 was at the intraspecific level,and the species T.sp.2(sensu Nakabo,2002) from Japan should be classified as T.margarites Li,1992.It has been suggested that T.margarites is widely distributed from the In-dian Ocean to the western Pacific,and not merely limited to the South China Sea,Taiwan Strait,and Taiwan coastal waters.Based on coalescent estimates of divergence times among species,the origin and evolution of T.margarites are primarily discussed in this study.

Phylogeography of Quercus phillyraeoides (Fagaceae) in Japan as revealed by chloroplast DNA variation

In order to elucidate the phylogeographical relationships and to find the past colonization routes of evergreen oak (Quercus phillyraeoides), we collected samples from 19 populations from the central to western part of Japan and examined chloroplast DNA sequence variation. We analyzed the genetic variation for four non-coding and one coding region and examined a total of 3,665 bp. Total nucleotide diversity (π) was 0.00017 ± 0.00001, and the scaled mutation rate (θw) was 0.00021 ± 0.00011. These values were relatively smaller than those formerly reported for Japanese deciduous oak species (Q. mongolica var. crispula). A total of five haplotypes, two of which included two subtypes (A1, A2, B, C, D1, D2, E), were identified, with types A1 and D2 the most frequent. A large degree of genetic differentiation had occurred across the populations (GST = 0.833 for haplotype data and FST = 0.858 for sequence data). The data suggested several possible refugia populations on the Pacific Ocean coast and the East China Sea coast, nearly identical to those previously suggested for the lucidophyllus forest refugia. We could not find any evidence showing that any part of the Seto Inland Sea populations could be possible refugia. Largest genetic differentiation across the populations in the Seto Inland Sea region suggests that these areas have been recently colonized following the last glacial maximum from the refugia in the Pacific coast or in southern Kyushu.

Distributions and sources of polychlorinated biphenyls in the coastal East China Sea sediments

The Yangtze River estuary (YRE) and the adjacent East China Sea (ECS) inner shelf is an important sink of pollutants originated from mainland China. In this work, we studied the spatial and temporal variations and sources of polychlorinated biphenyls (PCBs) in sediments from the YRE and the ECS inner shelf. Total concentration of 23 PCBs (Σ23PCB) ranged between 24.3 and 343.3pg/g (with a mean value of 126.7pg/g), and higher values occurred in the estuarine region. The homolog profile was dominated by 3–5Cl CBs, accounting for 76.1% of Σ23PCB. The Cl proportion ranged from 45.1% to 58.8% (with a mean value of 49.9%); the lowest level appeared in the estuarine region, and it increased with distance from the YRE. Lower chlorinated congeners were carried mainly by the YR into the ocean, to be finally buried in sediments of the estuary region and vicinity. However, higher chlorinated ones were imported mainly via direct emission from local sources, to be finally buried in sediments farther away from the estuary. Of the PCBs in surface sediments, 40.1% came from the YR, 37.9% from the local sources and the rest 22.0% from atmospheric deposition. In a sediment core, we found that 81% of PCBs were technically produced and 19% unintentionally produced in the last century. Before the 1970s, PCB levels were influenced predominantly by the production and consumption of technical PCBs. While in recent decades, the effect of human activities on PCB levels has been increasing continuously.

Source and Migration of Short-Chain Chlorinated Paraffins in the Coastal East China Sea Using Multiproxies of Marine Organic Geochemistry

Multiple proxies of terrestrial organic matters (TOM) were introduced to study the migration behaviors of short-chain chlorinated paraffins (SCCPs) in the coastal East China Sea (ECS). The contents of SCCPs in the surface sediment collected from Changjiang (Yangtze) River Delta (CRD) and along the Zhejiang-Fujian coastline ranged from 9.0 to 37.2 ng/g (dry weight, d.w.), displaying a "band-style" distribution trend. Spatial distribution patterns of SCCP congeners presented an increasing trend seaward and southward along the coastline for shorter carbon length (C₁₀ + C₁₁) and lower chlorinated (Cl₅ + Cl₆ + Cl₇) congeners, suggesting a spreading tendency seaward and southward from the CRD and the north of the inner shelf. The significant relationship between ΣSCCPs and total organic carbons (TOC) (r(2) = 0.402, p < 0.05) indicated that the migration of SCCPs in sediments was markedly affected by TOC. The spatial patterns of the TOM proxies of TOC δ(13)C, the contents of ΣC₂₇ + C₂₉ + C₃₁ n-alkanes, terrestrial marine biomarker ratio (TMBR), and terrestrial TOC (T-TOC) were all similar to that of ΣSCCPs. Linear relationships between SCCP contents and both the contents of ΣC₂₇ + C₂₉ + C₃₁ n-alkanes (r(2) = 0.537, p < 0.05) and T-TOC (r(2) = 0.495, p < 0.05) were also observed. The consistence demonstrated that a major portion of sedimentary SCCPs in the coastal ECS should be from the river input of Changjiang River and deposited in the CRD and along the inner shelf of the ECS, but only a minor fraction was transported to the offshore areas.