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Ready-to-eat wine-pickled mud snails (Bullacta exarata) typically host a large number of microorganisms and are frequently contaminated with pathogenic bacteria during processing, resulting in a higher risk for foodborne illness with consumption. In this study, the decontamination effects of different treatment methods, including the use of ultrasonic cleaning (USC), natural chemicals, and ultra-high pressure (UHP), on the quality and safety of pickled mud snails were investigated by assessing the total viable count (TVC), total volatile base nitrogen (TVB-N) content, thiobarbituric acid-reactive substance (TBARS), and pH value of the products after 12 months of storage at –20 °C. Treatment with 200 W USC for 5 min was the most effective approach for reducing TVC in raw mud snails, with a minimal change in food quality. Natural chemical treatment or UHP treatment significantly inhibited the increase in TVC, pH, and TBARS and TVB-N accumulation compared with the control group; however, their combined treatment had no synergistic effect. In contrast, the combined chemical treatment was more effective in inhibiting changes in the above indices in pickled mud snails than UHP treatment alone or combined chemicals+UHP treatment. In addition, the bacterial diversity of pickled mud snails before and after 12 months of storage at –20 °C was determined using Illumina MiSeq sequencing. Our results indicated that USC combined with natural chemicals can be utilized commercially to maintain the quality and safety of pickled mud snails during storage at –20 °C.

Ulva usually attached to aquaculture rafts, rocks, and floating objects. Previous studies have shown that the world's largest green tides in the Yellow Sea originated from the attached Ulva on rafts. However, a large biomass of Ulva thalli has recently been found attached to Littorina sp. (periwinkles) in the Subei intertidal zone, but it is rarely observed on Bullacta exarata, Portunus sp., and other intertidal benthic animals. The population density of Littorina sp. on the Zhugen sand ridge is approximately 39.2 specimens/m2. A maximum of seven Ulva macroalgae were attached to one periwinkle, and an average of 1.24 Ulva macroalgae were attached to each periwinkle. To determine the contribution of epizoic Ulva on Littorina sp. to floating green tides, these macroalgae were identified with a molecular biology method using internal transcribed spacer (ITS) sequences. Results showed the Ulva attached to Littorina sp. comprised just one species, Ulva flexuosa. Epizoic Ulva attached to intertidal benthic animals in the Zhugen sand ridge does not appear to be the main source of the green tide (the only dominant species is Ulva prolifera) outbreaks in the Southern Yellow Sea.

In recent years, the rapid economic development as well as the increase in people entering and exiting help to promote the introduction of alien species. Risk evaluation of alien species is the basis of developing risk management of alien species and one the most effective method to prevent the intrusion of alien species. Ecological risk of alien species Bullacta exarata in Yellow River Delta was evaluated by this article. The result shows that Bullacta exarata has certain effects on ecological environment in Yellow River Delta, but these effects are acceptable. However, we need to be cautious in development and also prevent significant effects of mass reproduction of mud snail on the local ecological environment.

Since the mud snail Bullacta exarate was introduced for economic aquaculture in the Huanghe River (Yellow River) Delta in 2001, its quick population growth and expanded distribution make it a key-species in the intertidal zone of this area. This significantly contributed to the economic income of the local people, but its potential ecological impact on the benthic ecosystem remains unknown. A mesocosm study was conducted to test whether its bioturbation activities affect the microphytobenthos (MPBs; i.e., sedimentary microbes and unicellular algae) productivity and the nutrient exchange between the sediment-water interface. Our results show that the mud snail significantly impacted the dissolved oxygen (DO) flux across the sediment-water interface on the condition of normal sediment and light treatment, and significantly increased the ammonium efflux during recovery period in the defaunated sediment and dark treatment. The presence of micro- and meiofauna significantly increased the NH4-N flux in dark treatment. Whereas, in light treatment, these small animals had less effects on the DO and NH4-N flux between sediment-water interface. Our results provide better insight into the effect of the mud snail B. exarate on the ecosystem functioning via benthic fluxes.

Thermal processing (TP) combined with multi-cycle high pressure processing (HPP) was explored to inactivate microbes in Bullacta exarata . Samples processed by TP with multi-cycle HPP were analyzed both by culture-dependent and -independent methods during refrigerated storage. Total microbial counts, psychrophilic bacteria counts, pH values, and conductivities were determined. TP and HPP processes resulted in higher pH and conductivity values, and also the conductivities of samples were significantly increased ( P B . exarata was composed mainly of Proteobacteria (40.59%), Firmicutes (36.43%) and Tenericutes (9.85%). Samples processed with HPP60 had the lowest bacterial diversity, and samples processed with HPP30 had the highest bacterial diversity. Bacterial diversity increased initially, and then decreased finally during refrigerated storage. These results demonstrated that HPP60 combined treatment is an effective method for food processing conditions.

High hydrostatic pressure (HHP) processing is an industrial technology used for preservation of a wide range of food products, and vacumm-packed mud snails ( Bullacta exarata ) were HHP processed to ensure food safety and shelf-life stability. The effects of single- and multi-cycle HHP treatment, especially the combination of different intensities, on the microbial behavior and shelf-life extension of B. exarata during subsequent storage were investigated. Total microbial count, psychrophilic microorganisms, Clostridium bacteria, total Enterobacteriaceae and H 2 S-producing bacteria were enumerated during subsequent refrigerated storage, and Gompertz model was chosen to predict the shelf-life, growth rate, lag time and generation time. The results showed that the initial microbial load was obviously reduced as the pressure increased. Total Enterobacteriaceae and H 2 S-producing bacteria were not detected in multi-cycle HHP processing during refrigerated storage. Moreover, multi-cycle HHP method (B + F) could improve the shelf-life of B. exarata for more than 38 days. The model indicated that the lag time for Clostridium bacteria processed with multi-cycle HHP (B + F) was extended to 24.65 days. Our findings will be of aid for the establishment of general process guidelines, and demonstrated that multi-cycle HHP technology has potential for application in mud snail preservation and processing.

The intertidal macrobenthos in the sand flats of the Shuangtaizi Estuary, Bohai Sea in China, were investigated in the spring, summer, and autumn in 2013 to identify the macrobenthic community of species components, abundance, and biomass. Twenty-nine species were identified, and classified primarily as mollusks (45%), polychaetes (31%), and crustaceans (21%). The abundance and biomass of the macrobenthos in the intertidal zone of the Shuangtaizi Estuary exhibited distinct seasonal patterns; both factors were higher in summer (16,762 ind/m2 and 782.5 g/m2, respectively) than in spring or autumn. The intertidal macrobenthos displayed a remarkable vertical distribution, and exhibited typical characteristics of estuaries: polychaetes such as Perinereis aibuhitensis distributed in the high tidal zone. Mollusks, such as Bullacta exarata, Potamocorbula laevis, and Umbonium thomasi mainly inhabited the mid-tidal zone. The buried clams Mactra veneriformis and Meretrix meretrix were dominant in the mid-tidal and low tidal regions, where the two clams shared overlapping habitats to some extent. Moreover, these benthic species were also highly abundant in the sections near the Shuangtaizi River mouth (23,661 ind/m2), but were detected as a high biomass in the sections far from the mouth (1492.9 g/m2). The bivalve P. laevis and M. veneriformis primarily contributed to the abundance and biomass of mollusks. The average Shannon–Wiener, evenness, and species richness indices of the intertidal macrobenthos in the estuary were 0.83, 0.37, and 0.45, respectively. The surface sediments in the intertidal zone consisted mainly of clay, silt sand, fine-grained sand, and sand types, which were closely related to the distributions of macrobenthos. Our study suggests that the Shuangtaizi Estuary is an important shellfish fishery, and the high abundance and biomass of P. laevis and U. thomasi can be exploited further. However, effective measures should be implemented to protect and restore the population of the clam M. meretrix.

Ready-to-eat wine-pickled Bullacta exarata was treated by atmospheric cold plasma (ACP) at 40, 50 and 60 kV for 3 min and stored at 4 °C for 0, 3, 6, 9 and 12d. The changes of moisture, total fat, total protein content, total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), microbial quality and amino acid composition in ACP treated and untreated wine-pickled B. exarata were investigated. Results showed that total protein content, pH, TVB-N and TBARS had no significant difference among groups including ACP treatment (40 kV、50 kV、60 kV) and control group, while moisture, total fat and microbial quality had significant difference, especially in 60 kV ACP treatment group. pH, TVB-N, TBARS and total viable count significantly increased over the refrigerating storage (3, 6, 9 and 12 d), although samples treated with ACP showed lower increases, especially for the highest voltage (60 kV). Serine, glutamine, aspartic acid, glycine, threonine, leucine content increased significantly while histidine and tyrosine decreased in ACP treatment group. It was concluded that ACP could prolong the shelf life of ready-to-eat wine-pickled B. exarata with weak influence on basic composition.

In China, edible shellfish are recognized as foods potentially at high risk of contamination with human Norovirus (HuNoV) and Vibrio parahaemolyticus. In this study, the antimicrobial effects of Chinese rice wine on HuNoV surrogates (MS2 and MNV-1) and V. parahaemolyticus in pickled mud snails immersed at different temperatures were evaluated. The optimized conditions for the wine treatment were also determined by assessing the color, odor, off-flavor, taste, and texture of the mud snails. Treatment with Chinese rice wine and immersion at 16 °C for 6 h were found to be the most effective conditions for reducing the incidence of MS2, MNV-1, and V. parahaemolyticus in the wine-treated mud snails with minimal changes to food quality. Using the nonlinear Weibull model, we show that the minimal TR values (the time required to reduce the population of pathogens by 90%) for MNV-1 (0.436 h), MS2 (0.363 h), and V. parahaemolyticus (0.202 h) were obtained for the rice-wine-containing shellfish immersed at 16 °C. Therefore, Chinese rice wine can be used as an antimicrobial agent against HuNoV and V. parahaemolyticus in wine-treated Bullacta exarata.

Many phylogeographic studies on marine organisms in the Northwestern Pacific have supported for the biogeographic hypotheses that isolation in the marginal seas of this region during the Pleistocene glaciation lower sea level led to population genetic divergence, and thus population expansion was a common phenomenon when the sea level rebounded. However, most of these studies were based on maternally inherited mitochondrial DNA markers with limited sample sites and therefore, were unable to reveal detailed pictures encompassing paternal line information covering of the entire range. In this study, we used the mitochondrial cytochrome c oxidase subunit I (COI) and nine nuclear microsatellite loci to investigate the phylogeography of the mud snail, Bullacta exarata (Philippi, 1849), a species endemic to the Northwestern Pacific. We sampled 14 natural populations spanning across 3800 km of the Chinese coastline, essentially covering most of the species distribution range. COI analysis identified a total of 149 haplotypes separated into two distinct groups with nine mutation steps, revealing a prominent phylogeographic structure. Nuclear microsatellite data also demonstrated a similar but weaker genetic structure. The estimated time to the most recent common ancestor between the two COI haplogroups is at ∼0.89 Ma, indicating that B. exarata populations survived the Pleistocene glaciation in the Sea of Japan and the Okinawa Trough, two marginal seas around the species range. The consistent significant patterns of isolation by distance of both COI and microsatellites suggests that limited mobility of adults and short planktonic stage of larvae may have played an important role in promoting or maintaining the genetic differentiation of B. exarata. Results from population demographic analyses support population expansion late in the Pleistocene era.

Bullacta exarata has been consumed in Asia, not only as a part of the normal diet, but also as a traditional Chinese medicine with liver- and kidney-benefitting functions. Several scientific investigations involving extraction of biomolecules from this mollusk and pharmacological studies on their biological activities have been carried out. However, little is known regarding the antitumor properties of polysaccharides from B. exarata, hence the polysaccharides from B. exarata have been investigated here. One polysaccharide conjugate BEPS-IA was isolated and purified from B. exarata. It mainly consisted of mannose and glucose in a molar ratio of 1:2, with an average molecular weight of 127 kDa. Thirteen general amino acids were identified to be components of the protein-bound polysaccharide. Methylation and NMR studies revealed that BEPS-IA is a heteropolysaccharide consisting of 1,4-linked-α-d-Glc, 1,6-linked-α-d-Man, 1,3,6-linked-α-d-Man, and 1-linked-α-d-Man residue, in a molar ratio of 6:1:1:1. In order to test the antitumor activity of BEPS-IA, we investigated its effect against the growth of human hepatocellular carcinoma cells HepG2 in vitro. The result showed that BEPS-IA dose-dependently exhibited an effective HepG2 cells growth inhibition with an IC50 of 112.4 μg/mL. Flow cytometry analysis showed that BEPS-IA increased the populations of both apoptotic sub-G1 and G1 phase. The result obtained from TUNEL assay corroborated apoptosis which was shown in flow cytometry. Western blot analysis suggested that BEPS-IA induced apoptosis and growth inhibition were associated with up-regulation of p53, p21 and Bax, down-regulation of Bcl-2. These findings suggest that BEPS-IA may serve as a potential novel dietary agent for hepatocellular carcinoma.

From April to July 2012, four species of univalves were selected and 60 samples were chosen from each species of univalves by random sampling in Dandong market. The heavy metal contents of Pb, Cd, Cr, Cu, Zn, total As and total Hg in the edible parts of the univalves were determined by using incomplete digestion - AAS method, and the assessment on the pollution situation of the four species of univalves was made by using the single factor index method. The results showed that bullacta exarata was slightly polluted by Zn, the pollution index was 0.65, and the edible value was threatened, which should be paid attention to. The heavy metal contents in the edible parts of the other univalves were far lower than the pollution limit of the national standard of food safety and the edible value was safe. The heavy metal accumulation ability in bullacta exarata is higher than in the other three species of univalves. Bullacta excta should be the biological indicator for the monitoring of heavy metal pollution.

Based on the monitoring data obtained from Haizhou Bay of Lianyungang in 2008, the concentrations and distributions of the heavy metals in surface water, surface sediments and benthos were studied. The results showed that the concentrations of heavy metals in water were lower than standard, the sediment quality was good. The contents of Zn, Cu, Pb, Cd, Ni, and Hg in benthos were lower than assessment standards, Bullacta exarata was polluted by As, all animals were polluted by Cr. Organisms possessed different accumulation capacities for different heavy metals.

Three sulphated polysaccharides, coded as BEMPA, BEMPB(1), BEMPB(2), were extracted from the mucilage of mud snail of Bullacta exarata and purified by DEAE-cellulose ion-exchange and size-exclusion chromatography. Structural analysis of purified polysaccharides by chemical and biochemical methods revealed BEMPA was a high (1→3,4)-linked mannose-containing polysaccharide with molecular weight of 22,977 Da. BEMPB(1), with molecular weight of 64,117 Da, was a high (1→3)-linked arabinose-containing polysaccharide. BEMPB(2) was mainly composed of (1→3,4)-linked mannose with molecular weight of 47,507Da. The comparison between sulphated polysaccharides and their desulphated products showed that sulphate substitutions of BEMPB(1) were deduced to be at the C-3 of (1→4)-linked mannose, while sulphate substitutions of BEMPA and BEMPB(2) were at C-4 of (1→3)-linked mannose. Furthermore, BEMPA exhibited highest inhibitory effects on growth of B-16 melanoma cells, and IC(50) were 31.1 μg/mL.

In this paper new data on the systematics, phylogeny, and trophic ecology of Bullacta exarata (Philippi, 1849) are presented. B. exarata is a cephalaspidean gastropod endemic to the China Sea that lives in estuaries along the north-eastern Chinese and western South Korean coastlines. The systematic position of this species is controversial and has been a matter of continuous debate. Therefore, in order to produce new insights into the phylogenetic position of this species, morphological and anatomical features have been analysed through fine dissection work and scanning electron microscopy (SEM), together with DNA sequence data. Bayesian phylogenetic inference based on concatenated sequences of the mitochondrial gene cytochrome c oxidase subunit I (COI) and nuclear genes 18SrRNA and 28SrRNA, suggests the inclusion of B. exarata in the family Haminoeidae. SEM analysis of gut contents revealed that B. exarata feeds upon diatoms.

On the Jiangsu coast, eastern China, Spartina alterniflora , which was introduced artificially into the region, is becoming a dominant plant species in the inter-tidal salt marshes. In order to evaluate the environmental and ecological impact of the colonization of S. alterniflora , we carried out investigations into the benthic macrofauna of the Spartina marshes of the Wanggang area, central Jiangsu coast, in 2006 and 2007. Based on analysis of the data sets obtained, 12 species of macrobenthos have been identified for the Wanggang salt marsh, including S. alterniflora , Cerithidea cingulata , Littorna scabra , Bithynia fuchsiana , Macrophthalmus japonicus , Uca arcuata , Nereis sp . , Boleophthalmus petinirostris , Cyclina sinensis , Bullacta exarata , Angustassiminea castanea and Glaucomya chinensis . The results indicate that some of the native species have adapted to the new ecological environment associated with the cordgrass S. alterniflora . The biomass of macrobenthos varies significantly over different parts of the salt marsh. Further, there is a seasonal change in bio-density, with the density in summer (July and August) > autumn (November) > early summer (May). At the landward edge and over the central part of the S. alterniflora marsh, the bio-diversity is higher than the other areas of the marsh.

The mud snail Bullacta exarata is commercially one of the most important marine snails in China, endemic to the coastlines of north-east China and west South Korea. However there is controversy regarding whether the mud snail is an invasive species or whether Laizhou Bay has a historical natural distribution, with little information available on population genetics. In this study, 14 novel polymorphic microsatellite loci were isolated from the mud snail, and characterized in wild stock from Laizhou Bay of China. The number of alleles varied between 4 and 19, and the observed and expected heterozygosity at the population level varied from 0.1875 to 1.0000 and 0.7172 to 0.9379, respectively. Five locus Bex26-166, Bex28-188, Bex29-115, Bex32-179 and Bex34-148 significantly deviated from the Hardy–Weinberg equilibrium (P < 0.01). These microsatellite markers will be useful for population genetics, alien and invasive species identification, parentage studies of this species.

The bacterial flora in the digestive tube of Bullacta exarata Philippi and its rearing shoal were investigated. A total of 157 strains of heterotrophic bacteria, isolated from crop, stomach intestine and other parts of the digestive tube, mainly belong to the genera Photobacterium, Bacillus, Pseudomonas Vibrio and some genera of the family Enterobacteriaceae. There are significantly more varieties of bacteria in crop than in stomach and intestine. A total of 173 strains of bacteria were isolated from the rearing shoal, belonging to 13 genera. The 5 predominant genera, such as Bacillus and Photobacterium, are the same as those in the digestive tube, but greatly differ in percentages. The number of heterotrophic bacteria and Vibrio in rearing shoal change in line with the alteration of the temperature, and are significantly affected by the use of pesticides.

The contents of zinc, copper, lead and cadmium were measured in the dominant species (plants:Scripus triquetor andPhrgrmites australis, macrobenthos:Ilyoplax deschampsin, Helice tridens tientsinensis, Bullacta exarata and Corbicula fluminea, and migrating waders: Calidris ruficollis and C. alpina) of the ecosystem of Yangtze Estuary, China, from 1995–1998. Results show that: (1) Since the heavy metals stored in plants during growth seasons will be released into the environment in winter, plants are temporary stocks for metals. For the aboveground parts of reeds, about 156.6 kg·ha-1·a-1 of zinc, 369.9 kg·ha-1·a-10 of copper, 32.9 kg·ha-·a-1 of lead and 6.5 kg·ha-1·a-1 of cadmium were released. (2) The mollusca, especially C.fluminea, are the key species storing and transporting heavy metals on the food chain. (3) The temporal change in the highest trophic level was studied and found that it was significantly related with metabolic rates. The contents of heavy metals in Dunlin reach the peaks in January and October, which are wintering season and migratory season, respectively, of the bird. (4) Organisms often show regulation/accumulation mechanisms to different elements of heavy metals. The elements that are widely required, such as zinc and copper, are accumulated at the metabolically active parts. It is quite another thing for the other two elements. Lead was regulated well and scarcely accumulated in the bodies of macrobenthos, but cadmium was absolutely accumulated in the animals. (5) Heavy metals were found accumulated in some parts of the bodies of these organisms, such as shells and skeletons of macrobenthos and lives and muscles of waders. (6) All these four elements were accumulated higher in the bodies of waders than in the plants and macrobenthos, which showed a bio-magnification function of the food chain. Overall, besides the physical and chemical processes, biological processes of heavy metal elements in Yangtze Estuarine ecosystem play a very important role in self-purification function of the ecosystem. Measurement of heavy metal contents in plants and animals in the estuarine ecosystem is an efficient technology for monitoring the environmental quality of the estuary.

Sixteen polymorphic microsatellite markers were developed from a partial genomic library enriched using AG and AC repeats in mud snail (Bullacta exarata). Polymorphism of these loci was screened using 48 adult individuals of B. exarata. The number of alleles per locus ranged from 2 to 13. The observed and expected heterozygosities ranged from 0.5106 to 0.8125 and from 0.4868 to 0.9208, respectively. One locus departed significantly from Hardy–Weinberg equilibrium after Bonferroni correction. No linkage disequilibrium was found between any pair of loci. These polymorphic microsatellite markers are expected to provide valuable genetic information in population structure and genetic diversity, which will certainly facilitate management strategies of the mud snail.

Nine polymorphic microsatellite loci were isolated and characterized from an AC-enriched genomic library of Bullacta exarata. They were polymorphic in 30 individuals from Qidong in Jiangsu Province, China. The number of alleles per polymorphic loci varied from 7 to 14 and the values of observed heterozygosity and expected heterozygosity ranged from 0.2593 to 0.9667 and from 0.7090 to 0.9164, respectively. Six of the nine microsatellites conformed to Hardy–Weinberg equilibrium, and inherited independently. These informative microsatellite markers will be useful in studies of population genetic structure for this species.

Bullacta exarata was hydrolyzed with trypsin to prepare peptides; Hydrolysates were isolated by ultrafiltration and purified using G-25 gel filtration. The purity of the Bullacta exarata was demonstrated by HPLC and its peptide sequence analysis was detected. The effects of BEPT II and BEPT II-1 on the proliferation of PC-3 cells were examined using a MTT assay. BEPT II and BEPT II-1 significantly inhibited the proliferation of PC-3 cells in a time- and dose-dependent manner. Annexin V/PI double staining studies showed exposing PC-3 cells to 5, or 15 mg/mL BEPT II-1 for 24 h increased the percentage of the early stage of apoptotic cells from 11.22% to 22.09%. In addition, typical morphologic changes were observed in the cells with acridine orange/ethidium bromide staining. These data support that BEPT II-1 has anticancer properties and merits further investigation to understand the mechanisms of BEPT II-1-induced apoptosis in PC-3 cells.

In the present study different biomarker responses and genotoxicity were determined in wild mud snails (Bullacta exarata) collected from 3 sampling sites in Bohai Bay in northeastern China, which is a region that is under considerable anthropogenic influence. Significant spatial variability of superoxide dismutase (SOD) and metallothionein (MT)-like proteins were recorded, while glutathione transferase (GST), catalase (CAT), and vitellin-like proteins (Vn’s) were not observed. Furthermore, genomic DNA that was amplified with 4 fluorescence-labeled primer pairs showed variable genetic distances among the 3 wild mud snail populations found in Bohai Bay, which may be correlated with differences in the types of environmental genotoxicants, such as heavy metals and polycyclic aromatic hydrocarbons. This multi-biomarker approach provided an improved understanding of the potential toxicological impact of contaminated sediments on benthic organisms.

The morphology and ultrastructure of Bullacta exarata spermatozoa observed by light and transmission electron microscopy are presented in this paper. The spermatozoon is composed of head with a simple acrosomal complex and an elongated nucleus, and tail with a midpiece, principal piece and an end piece. The midpiece consists of a mitochondrial ring, and the principal piece is composed of axoneme and lateral fin. The structure of B. exarata spermatozoa differs significantly from that of other gastropods, especially in the lateral fin and the principal piece, which was described scarcely before. A comparison is made between B. exarata and other gastropods, and its significance on reproductive evolution and physio-ecological adaptation is preliminarily discussed.

Macrobenthos samples were collected from three sections in the intertidal zone of the Changjiang Estuary in August 2010,November 2010 and May 2011,and the parameters of the density,biomass,secondary productivity,and P/B value of the macrobenthos were measured based on the equation by Brey(1990).The foundings indicated that the total mean density of the macrobenthos was 637.83 ind m-2,total mean biomass in ash free dry mass(AFDW) was 6.71 g m-2,total mean annual secondary productivity was 6.91 g m-2 a-1,and total mean annual P/B value was 1.01 a-1,respectively.Three sections ordered by the total mean density,biomass,secondary productivity,and P/B value was Dongwang sand Buyu port Tuanjie sand.The secondary productivity was mainly influenced by Crustacea with six critical species,including Corbicula fluminea,Potamocorbula amurensis,Sinonovacula constricta,Stenothyra glabra,Bullacta exarata and Cerithidea sinensis,and the six species contributed 65.24% of the total.Based on the data of total mean annual P/B value(1.01 a-1),It was speculated that the average change of macrobenthos was year-generation,and community structure was instability and obviously influenced by the environment.The analyses of secondary productivity combination of variables indicated that the secondary productivity was not only impacted by the biomass and density but also by the total nitrogen and total phosphorus of water.The results of Principal Components Analysis(PCA) on the environmental variables showed that the environment in Tuanjie Sand was the most stable,Buyu Port was less stable,and Dongwang Sand was the most violent one.The relationship between environmental variables and the secondary productivity of community was analyzed using Canonical Correspondence Analysis(CCA),and Sa,TP,TOC and DO were found to be the key factors to the secondary productivity in Dongwang Sand macrobenthos communities;TN,TOC,Chla and DO in Buyu port.Furthermore,the habitat of Tuanjie Sand was the most stable,and all the environmental variables of this region rarely changed,so it was speculated that the physical factors were the key factors of the secondary productivity.

In April, July and November 2002 and April 2003, a quadrat investigation of macrobenthos was conducted at four sampling profiles in the intertidal flat of Yangtze Estuary. The concentrations of Cu, Pb, Fe, Mn, Zn and Cr in several high biomass macrobenthos were determined, their absorbed amounts per square meter were calculated, and the biological quality of Corbicula fluminea and Siliqua minima was evaluated. The results showed that C. fluminea was widespread in the intertidal, especially in the low tidal flat of Yangtze Estuary, and heavy metals were mainly concentrated in its soft tissues. C. fluminea could selectively absorb Cu, leading to the little variation of Cu concentration in the tissues of C. fluminea sampled from different coastal region. Mollusks Rissoina sp. and Bullacta exarata, and all crustaceans could markedly accumulate Cu in their bodies, and the BSAF value reached 2.97-7.97. The mollusks and crustaceans had the greatest absorption of Fe per square meter, followed by Mn, Zn and Cu, and Pb and Cr. The amount of Cu, Pb, Fe and Cr absorbed by B. exarata larva from per square meter intertidal flat was obviously higher than that by other macrobenthos, while the absorbed amount of Mn and Zn in B. exarata larva was less than that in C. flunzinea collected from XuPu. The concentrations of Pb and Cr in the soft tissues of C. fluninea and S. miniema were relatively lower in the intertidal flat of Yangtze Estuary than in other coastal and estuarine areas, and those of Cu and Zn were also low but at appreciable level. Compared to the criterion for marine biological quality in China, the edible soft tissue of Corbicula fluminea and S. minima in the tidal flat of Yangtze Estuary was relatively safe for human beings.