Spartina alterniflora Loisel, a species vegetating in intertidal flats along the eastern coast of the United States, was introduced in China almost 30 years ago and has become an urgent topic due to its invasiveness i...Spartina alterniflora Loisel, a species vegetating in intertidal flats along the eastern coast of the United States, was introduced in China almost 30 years ago and has become an urgent topic due to its invasiveness in the coastal zone of China. The impacts of this alien species S. alterniflora on intertidal ecosystem processes in the Jiangsu coastland were investigated by comparing the sediment nutrient availability and trace element concentration characteristics in a mud flat and those of a four-year old Spartina salt marsh that had earlier been a mudflat. At each study site, fifteen plots were sampled in different seasons to determine the sediment characteristics along the tidal flats. The results suggested that Spartina salt marsh sediments had significantly higher total N, available P, and water content, but lower pH and bulk density than mudflat sediments. Sediment salinity, water content, total N, organic C, and available P decreased along a seaward gradient in the Spartina salt marsh and increased with vegetation biomass. Furthermore, the concentrations of trace elements and some metal elements in the sediment were higher under Spartina although these increases were not significant. Also, in the Spartina marsh, some heavy metals were concentrated in the surface layer of the sediment. The Spartina salt marsh in this study was only four years old; therefore, it is suggested that further study of this allen species on a longer time frame in the Jiangsu coastland should be carried out.展开更多
Biochar (BC) and rhamnolipid (RL) is used in bioremediation of petroleum hydrocarbons,however,the combined effect of BC and RL in phytoremediation has not been studied until now.In this paper,the phytoremediation of p...Biochar (BC) and rhamnolipid (RL) is used in bioremediation of petroleum hydrocarbons,however,the combined effect of BC and RL in phytoremediation has not been studied until now.In this paper,the phytoremediation of petroleum hydrocarbon-contaminated soil using novel plant Spartina anglica was enhanced by the combination of biochar (BC) and rhamnolipid (RL).Samples of petroleum-contaminated soil (10,30 and 50 g/kg) were amended by BC,BC+ RL and rhamnolipid modified biochar (RMB),respectively.After 60 day's cultivation,the removal rate of total petroleum hydrocarbons (TPHs) for unplanted soil (UP),planted soil (P),planted soil with BC addition (P-BC),planted soil with BC and RL addition (P-BC + RL) and planted soil with addition ofRMB (P-RMB) were 8.6%,19.1%,27.7%,32.4% and 35.1% in soil with TPHs concentration of 30 g/kg,respectively.Compared with UP,the plantation of Spartina anglica significantly decreased the concentration of C8-14 and tricyclic PAHs.Furthermore,the application of BC and RMB alleviated the toxicity of petroleum hydrocarbons to Spartina anglica via improving plant growth with increasing plant height,root vitality and total chlorophyll content.High-throughput sequencing result indicated that rhizosphere microbial community of Spartina anglica was regulated by the application of BC and RMB,with increase of bacteria and plant mycorrhizal symbiotic fungus in biochar and RMB amended soil.展开更多
The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is hi...The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is highly complicated. The cord-grass Spartina alterniflora, which was introduced artificially into the Jiangsu coast, has significant influences on the regional tidal flat evolution in terms of deposition rate, spacial sediment distribution patterns and tidal creek morphology. On the basis of the data set of bed elevation and accumulation rate for different periods of time, the applicability of the Pethick - Allen model to the Jiangsu tidal salt marshes is discussed. In addition, caesium-137 dating was carried out for sediment samples collected from the salt marsh of the Wangang area. In combination with the caesium-137 analysis and the data collected from literature, the Pethick - Allen model was used to derive the accumulation rate in the Wanggang tidal flat for the various periods. The results show that the pattern of tidal flat accretion has been modified, due to more rapid accretion following the iatroduction of S. alterniflora to the region. Surficial sediment samples were collected from representative profiles and analyzed for grain size with a laser particle analyzer. The result shows that fine-grained sediment has been trapped by the plant, with most of the sediment deposited on the Suaeda salsa and Spartina angelica flats being derived from drainage creeks rather than the from gently sloping tidal flats. Remote sensing analysis and in situ observations indicate that the creeks formed in the S. alterniflora flat have a relatively small ratio of width to depth, a relatively high density, and are more stable than the other tidal flat creek systems in the study area.展开更多
Spartina alterniflora is ecologically important in its original habitat; however, it has caused controversy since it was introduction into China(now it has been spreading rapidly on the Jiangsu, Shanghai, Zhejiang and...Spartina alterniflora is ecologically important in its original habitat; however, it has caused controversy since it was introduction into China(now it has been spreading rapidly on the Jiangsu, Shanghai, Zhejiang and Fujian coasts). The purpose of the present contribution is, on the basis of an analysis and synthesis of existing data sets, to evaluate the environmental-ecological effects of S. alterniflora, and to identify the relevant scientific problems that require further research in the future. Investigations have shown that, by reducing the near-bed shear stress associated with tidal currents, S. alterniflora can enhance the settling flux of suspended sediment and deposition rate on the tidal flats over the region. Further, field survey and analysis indicate that the S. alterniflora salt-marsh has a high primary production and provides a new type of habitat for the native benthic fauna. Some macro-, meio- and micro-fauna that used to live in the native salt-marshes have adapted to the S. alterniflora salt-marsh, forming a new ecosystem. Under the influences of a number of background factors, such as latitude variations and the coastal type, the environmental-ecological changes induced by Spartine have regional differentiations. To the north of Hangzhou Bay, with a high position of the pre-Holocene stratum base, a large width of the tidal flats, and a gentle bed slope, only a small part of the intertidal zone is occupied by the S. alterniflora salt-marsh. Here, the S. alterniflora salt-marshes mainly play a positive role in coastal protection and ecosystem functioning. In contrary, to the South of Hangzhou Bay, The pre-Holocene deposits are situated in relatively deeo waters, and the width of the tidal flats formed within coastal embayments is relatively narrow. As such, the expansion of S. alterniflora has squeezed the living space of other intertidal organisms, thus has a negative ecological effect. Therefore, the regional differentiation of the Spartina effects should be sufficiently considered in coasta展开更多
Four sites were selected in a salt marsh in the Bahia Blanca Estuary （Argentina）： （1） low marsh （flooded by the tide twice daily） vegetated by S. alterniflora; （2） non-vegetated low marsh; （3） high marsh （...Four sites were selected in a salt marsh in the Bahia Blanca Estuary （Argentina）： （1） low marsh （flooded by the tide twice daily） vegetated by S. alterniflora; （2） non-vegetated low marsh; （3） high marsh （flooded only in spring tides） vegetated by S. alterniflora; （4） non-vegetated high marsh. The pH and Eh were measured in sediments, while dissolved nutrients （ammonium, nitrate, nitrite and phosphate） and particulate organic matter （POM） were determined in pore water, pH （6.2-8.7） was only affected by vegetation in low areas. Eh （from -300 to 250 mV） was lower at low sites than at high ones; in the latter, the values were higher in the non-vegetated sediments. The POM concentration was greater in the high marsh than in the low marsh, with no effect of vegetation. Ammonium was the most abundant nitrogen nutrient species in pore water, except in the non-vegetated high marsh where nitrate concentration was higher. All nitrogen nutrients were affected by both flooding and vegetation. Phosphate was always present in pore water at all sites throughout the year and its concentration varied within narrow limits, with no effect of flooding and greater values always at non-vegetated sites. Our results showed that the variability of the pore water composition within the marsh is greater than the temporal variation, meaning that both tidal flooding and vegetation are important in the dynamics of nutrients and organic matter in the sediment pore water.展开更多
The exotic species Spartina alterniflora(S.alterniflora)seriously threatens the stability and functioning of saltmarsh ecosystems in the Yangtze Estuary.Ambitious efforts have been undertaken to control this species,b...The exotic species Spartina alterniflora(S.alterniflora)seriously threatens the stability and functioning of saltmarsh ecosystems in the Yangtze Estuary.Ambitious efforts have been undertaken to control this species,but subsequent re-invasion is frequent,presenting a significant barrier to restoration.The complexity and high cost of integrated physical control programs has necessitated a shift in focus,leading to considerable attention being paid to the potential of herbicides to control S.alterniflora.To find a strategy for emergency control of small and scattered patches of re-invading S.alterniflora,an in situ field experiment using Gallant(Haloxyfop-R-methyl)herbicide was conducted.The growth parameters of plant density and height were used to evaluate the control efficiency of different treatment dosages and times and sediment samples were taken for environmental toxicity analysis.The results show the following:(1)the control efficacy of the maximum proposed application dose(2.70 g/m2)was 92%for continuous swards and 100%for small patches,while those of other dosages(0.45 g/m2,0.90 g/m2,and 1.35 g/m2)were lower than 40%;(2)the appropriate implementation time was July to August with 100%mortality resulting from a single application,while S.alterniflora was shown to be capable of recovering rapidly after treatment in May;and(3)there were no significant differences in the community structure of meiofauna among the herbicide treatments and the control,and no herbicide residues were detected in sediment samples collected from treatment areas.This chemical control method was implemented in the Shanghai Chongming Dongtan National Bird Nature Reserve(CDNR).The results of this study indicate that Gallant is an environmentally friendly herbicide with high efficiency,which can be adopted for emergency control of re-invading S.alterniflora.展开更多
The nitrogen （N） input and Spartina alterniflora invasion in the tidal marsh of the southeast of China are increasingly serious. To evaluate CH4 emissions in the tidal marsh as affected by the N inputs and S. altern...The nitrogen （N） input and Spartina alterniflora invasion in the tidal marsh of the southeast of China are increasingly serious. To evaluate CH4 emissions in the tidal marsh as affected by the N inputs and S. alterniflora invasion, we measured CH4 emissions from plots with vegetated S. alterniflora and native Cyperus malaccensis, and fertilized with exogenous N at the rate of 0 （NO）, 21 （N1） and 42 （N2） g N/（m2.yr）, respectively, in the Shanyutan marsh in the Minjiang River estuary, the southeast of China. The average CH4 fluxes during the experiment in the C. malaccensis and S. alterniflora plots without N addition were 3.67 mg CHa/（m2.h） and 7.79 mg CH4/（m2-h）, respectively, suggesting that the invasion of S. alterniflora into the Minjiang River estuary stimulated CH4 emission. Exogenous N had positive effects on CH4 fluxes both in native and in invaded tidal marsh. The mean CH4 fluxes of NI and N2 treat- ments increased by 31.05% and 123.50% in the C. malaccensis marsh, and 63.88% and 7.55% in the S. alterniflora marsh, respectively, compared to that of NO treatment. The CH4 fluxes in the two marshes were positively correlated with temperature and pH, and nega- tively correlated with electrical conductivity and redox potential （Eh） at different N addition treatments. While the relationships between CH4 fluxes and environmental variables （especially soil temperature, pH and Eh at different depths） tended to decrease with N additions. Significant temporal variability in CH4 fluxes were observed as the N was gradually added to the native and invaded marshes. In order to better assess the global climatic role of tidal marshes as affected by N addition, much more attention should be paid to the short-term temporal variability in CH4 emission.展开更多
Benthic macroinvertebrate communities in Spartina alterniflora zones in the Yangtze Estuary, in China, were investigated seasonally in 2005, and their structure and biodiversity were analyzed. Twenty-one species were ...Benthic macroinvertebrate communities in Spartina alterniflora zones in the Yangtze Estuary, in China, were investigated seasonally in 2005, and their structure and biodiversity were analyzed. Twenty-one species were identified, across four Classes; 10 species of Crustacea, five species of Polychaeta, five species of Gastropoda, and one species of Lamellibranchia. Dominant species included： Assiminea sp., Notomastus latericeus, Cerithidea largillierl, Gtauconome chinensi and Gammaridae sp. Functional groups were comprised of a phytophagous group and a detritivorous group. The average density of all benthic macroinvertebrates was 650.5 ±719.2 inds/m^2 in the survey area. The high value of the standard deviation of the average density was a result of abundant Assiminea sp. at Beihu tidal flats. The average density of macroinvertebrates from Beihu tidal flat, Chongming Dongtan to Jinshanwei tidal flat decreased gradually. There was significant difference between compositions and abundance of macroinvertebrates along the estuary gradient （P 〈 0.05）. The density and biodiversity were highest in summer and lowest in winter. The mean biomass of macroinvertebrates was 20.8 ± 6.1 g/m^2. Biomass changed seasonally in the same way as density, with the change in biomass being： summer （Aug.） 〉autumn （Oct.） 〉spring （Apr.） 〉 winter （Dec.）. A BIO-ENV analysis showed that the mean grain size of sediment, height of Spartina and salinity were the ma- jor factors which affected the structure of the macroinvertebrate community. Variations in the community structure were probably caused by the population dynamics of S. alterniflora along with the variation in sampling time and location.展开更多
基金Project supported by the Natural Science Foundation of Jiangsu Province (No.JSNSF 20050307)the National Natural Science Foundation of China (No.NSFC 30470326).
文摘Spartina alterniflora Loisel, a species vegetating in intertidal flats along the eastern coast of the United States, was introduced in China almost 30 years ago and has become an urgent topic due to its invasiveness in the coastal zone of China. The impacts of this alien species S. alterniflora on intertidal ecosystem processes in the Jiangsu coastland were investigated by comparing the sediment nutrient availability and trace element concentration characteristics in a mud flat and those of a four-year old Spartina salt marsh that had earlier been a mudflat. At each study site, fifteen plots were sampled in different seasons to determine the sediment characteristics along the tidal flats. The results suggested that Spartina salt marsh sediments had significantly higher total N, available P, and water content, but lower pH and bulk density than mudflat sediments. Sediment salinity, water content, total N, organic C, and available P decreased along a seaward gradient in the Spartina salt marsh and increased with vegetation biomass. Furthermore, the concentrations of trace elements and some metal elements in the sediment were higher under Spartina although these increases were not significant. Also, in the Spartina marsh, some heavy metals were concentrated in the surface layer of the sediment. The Spartina salt marsh in this study was only four years old; therefore, it is suggested that further study of this allen species on a longer time frame in the Jiangsu coastland should be carried out.
基金supported by the National Natural Science Foundation of China(Nos.U1806216,41877372)the CNPC scientific research and technological development project(No.2016D-4610)+1 种基金the Tianjin S&T Program(Nos.17ZXSTSF00050,17PTGCCX00240,16YFXTSF00520)the 111 program,Ministry of Education,China(No.T2017002)
文摘Biochar (BC) and rhamnolipid (RL) is used in bioremediation of petroleum hydrocarbons,however,the combined effect of BC and RL in phytoremediation has not been studied until now.In this paper,the phytoremediation of petroleum hydrocarbon-contaminated soil using novel plant Spartina anglica was enhanced by the combination of biochar (BC) and rhamnolipid (RL).Samples of petroleum-contaminated soil (10,30 and 50 g/kg) were amended by BC,BC+ RL and rhamnolipid modified biochar (RMB),respectively.After 60 day's cultivation,the removal rate of total petroleum hydrocarbons (TPHs) for unplanted soil (UP),planted soil (P),planted soil with BC addition (P-BC),planted soil with BC and RL addition (P-BC + RL) and planted soil with addition ofRMB (P-RMB) were 8.6%,19.1%,27.7%,32.4% and 35.1% in soil with TPHs concentration of 30 g/kg,respectively.Compared with UP,the plantation of Spartina anglica significantly decreased the concentration of C8-14 and tricyclic PAHs.Furthermore,the application of BC and RMB alleviated the toxicity of petroleum hydrocarbons to Spartina anglica via improving plant growth with increasing plant height,root vitality and total chlorophyll content.High-throughput sequencing result indicated that rhizosphere microbial community of Spartina anglica was regulated by the application of BC and RMB,with increase of bacteria and plant mycorrhizal symbiotic fungus in biochar and RMB amended soil.
基金supported financially by the National Natural Science Foundation of China under contract Nos 40231010 and 40476041the Marine Science Youth Fund of State 0ceanic Administration of China under contract No.2006312.
文摘The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is highly complicated. The cord-grass Spartina alterniflora, which was introduced artificially into the Jiangsu coast, has significant influences on the regional tidal flat evolution in terms of deposition rate, spacial sediment distribution patterns and tidal creek morphology. On the basis of the data set of bed elevation and accumulation rate for different periods of time, the applicability of the Pethick - Allen model to the Jiangsu tidal salt marshes is discussed. In addition, caesium-137 dating was carried out for sediment samples collected from the salt marsh of the Wangang area. In combination with the caesium-137 analysis and the data collected from literature, the Pethick - Allen model was used to derive the accumulation rate in the Wanggang tidal flat for the various periods. The results show that the pattern of tidal flat accretion has been modified, due to more rapid accretion following the iatroduction of S. alterniflora to the region. Surficial sediment samples were collected from representative profiles and analyzed for grain size with a laser particle analyzer. The result shows that fine-grained sediment has been trapped by the plant, with most of the sediment deposited on the Suaeda salsa and Spartina angelica flats being derived from drainage creeks rather than the from gently sloping tidal flats. Remote sensing analysis and in situ observations indicate that the creeks formed in the S. alterniflora flat have a relatively small ratio of width to depth, a relatively high density, and are more stable than the other tidal flat creek systems in the study area.
基金supported financially by the Basic Research Project in Jiangsu Province (Grant No. SBK2011012)an National Natural Science Foundation of China (Grant No. 40476041)
文摘Spartina alterniflora is ecologically important in its original habitat; however, it has caused controversy since it was introduction into China(now it has been spreading rapidly on the Jiangsu, Shanghai, Zhejiang and Fujian coasts). The purpose of the present contribution is, on the basis of an analysis and synthesis of existing data sets, to evaluate the environmental-ecological effects of S. alterniflora, and to identify the relevant scientific problems that require further research in the future. Investigations have shown that, by reducing the near-bed shear stress associated with tidal currents, S. alterniflora can enhance the settling flux of suspended sediment and deposition rate on the tidal flats over the region. Further, field survey and analysis indicate that the S. alterniflora salt-marsh has a high primary production and provides a new type of habitat for the native benthic fauna. Some macro-, meio- and micro-fauna that used to live in the native salt-marshes have adapted to the S. alterniflora salt-marsh, forming a new ecosystem. Under the influences of a number of background factors, such as latitude variations and the coastal type, the environmental-ecological changes induced by Spartine have regional differentiations. To the north of Hangzhou Bay, with a high position of the pre-Holocene stratum base, a large width of the tidal flats, and a gentle bed slope, only a small part of the intertidal zone is occupied by the S. alterniflora salt-marsh. Here, the S. alterniflora salt-marshes mainly play a positive role in coastal protection and ecosystem functioning. In contrary, to the South of Hangzhou Bay, The pre-Holocene deposits are situated in relatively deeo waters, and the width of the tidal flats formed within coastal embayments is relatively narrow. As such, the expansion of S. alterniflora has squeezed the living space of other intertidal organisms, thus has a negative ecological effect. Therefore, the regional differentiation of the Spartina effects should be sufficiently considered in coasta
基金supported by Agencia Nacional de Promoción Científica y Tecnológica (PICT N°0945/2006) of Argentina
文摘Four sites were selected in a salt marsh in the Bahia Blanca Estuary （Argentina）： （1） low marsh （flooded by the tide twice daily） vegetated by S. alterniflora; （2） non-vegetated low marsh; （3） high marsh （flooded only in spring tides） vegetated by S. alterniflora; （4） non-vegetated high marsh. The pH and Eh were measured in sediments, while dissolved nutrients （ammonium, nitrate, nitrite and phosphate） and particulate organic matter （POM） were determined in pore water, pH （6.2-8.7） was only affected by vegetation in low areas. Eh （from -300 to 250 mV） was lower at low sites than at high ones; in the latter, the values were higher in the non-vegetated sediments. The POM concentration was greater in the high marsh than in the low marsh, with no effect of vegetation. Ammonium was the most abundant nitrogen nutrient species in pore water, except in the non-vegetated high marsh where nitrate concentration was higher. All nitrogen nutrients were affected by both flooding and vegetation. Phosphate was always present in pore water at all sites throughout the year and its concentration varied within narrow limits, with no effect of flooding and greater values always at non-vegetated sites. Our results showed that the variability of the pore water composition within the marsh is greater than the temporal variation, meaning that both tidal flooding and vegetation are important in the dynamics of nutrients and organic matter in the sediment pore water.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFC1201100)the National Natural Science Foundation of China(Grant No.41876093)the Scientific Research Project of the Shanghai Science and Technology Committee(Grants No.17DZ1201902,18DZ1206506,and 18DZ1204802).
文摘The exotic species Spartina alterniflora(S.alterniflora)seriously threatens the stability and functioning of saltmarsh ecosystems in the Yangtze Estuary.Ambitious efforts have been undertaken to control this species,but subsequent re-invasion is frequent,presenting a significant barrier to restoration.The complexity and high cost of integrated physical control programs has necessitated a shift in focus,leading to considerable attention being paid to the potential of herbicides to control S.alterniflora.To find a strategy for emergency control of small and scattered patches of re-invading S.alterniflora,an in situ field experiment using Gallant(Haloxyfop-R-methyl)herbicide was conducted.The growth parameters of plant density and height were used to evaluate the control efficiency of different treatment dosages and times and sediment samples were taken for environmental toxicity analysis.The results show the following:(1)the control efficacy of the maximum proposed application dose(2.70 g/m2)was 92%for continuous swards and 100%for small patches,while those of other dosages(0.45 g/m2,0.90 g/m2,and 1.35 g/m2)were lower than 40%;(2)the appropriate implementation time was July to August with 100%mortality resulting from a single application,while S.alterniflora was shown to be capable of recovering rapidly after treatment in May;and(3)there were no significant differences in the community structure of meiofauna among the herbicide treatments and the control,and no herbicide residues were detected in sediment samples collected from treatment areas.This chemical control method was implemented in the Shanghai Chongming Dongtan National Bird Nature Reserve(CDNR).The results of this study indicate that Gallant is an environmentally friendly herbicide with high efficiency,which can be adopted for emergency control of re-invading S.alterniflora.
基金Under the auspices of National Natural Science Foundation of China(No.41301085)National Basic Research Program of China(No.2012CB956100)
文摘The nitrogen （N） input and Spartina alterniflora invasion in the tidal marsh of the southeast of China are increasingly serious. To evaluate CH4 emissions in the tidal marsh as affected by the N inputs and S. alterniflora invasion, we measured CH4 emissions from plots with vegetated S. alterniflora and native Cyperus malaccensis, and fertilized with exogenous N at the rate of 0 （NO）, 21 （N1） and 42 （N2） g N/（m2.yr）, respectively, in the Shanyutan marsh in the Minjiang River estuary, the southeast of China. The average CH4 fluxes during the experiment in the C. malaccensis and S. alterniflora plots without N addition were 3.67 mg CHa/（m2.h） and 7.79 mg CH4/（m2-h）, respectively, suggesting that the invasion of S. alterniflora into the Minjiang River estuary stimulated CH4 emission. Exogenous N had positive effects on CH4 fluxes both in native and in invaded tidal marsh. The mean CH4 fluxes of NI and N2 treat- ments increased by 31.05% and 123.50% in the C. malaccensis marsh, and 63.88% and 7.55% in the S. alterniflora marsh, respectively, compared to that of NO treatment. The CH4 fluxes in the two marshes were positively correlated with temperature and pH, and nega- tively correlated with electrical conductivity and redox potential （Eh） at different N addition treatments. While the relationships between CH4 fluxes and environmental variables （especially soil temperature, pH and Eh at different depths） tended to decrease with N additions. Significant temporal variability in CH4 fluxes were observed as the N was gradually added to the native and invaded marshes. In order to better assess the global climatic role of tidal marshes as affected by N addition, much more attention should be paid to the short-term temporal variability in CH4 emission.
文摘Benthic macroinvertebrate communities in Spartina alterniflora zones in the Yangtze Estuary, in China, were investigated seasonally in 2005, and their structure and biodiversity were analyzed. Twenty-one species were identified, across four Classes; 10 species of Crustacea, five species of Polychaeta, five species of Gastropoda, and one species of Lamellibranchia. Dominant species included： Assiminea sp., Notomastus latericeus, Cerithidea largillierl, Gtauconome chinensi and Gammaridae sp. Functional groups were comprised of a phytophagous group and a detritivorous group. The average density of all benthic macroinvertebrates was 650.5 ±719.2 inds/m^2 in the survey area. The high value of the standard deviation of the average density was a result of abundant Assiminea sp. at Beihu tidal flats. The average density of macroinvertebrates from Beihu tidal flat, Chongming Dongtan to Jinshanwei tidal flat decreased gradually. There was significant difference between compositions and abundance of macroinvertebrates along the estuary gradient （P 〈 0.05）. The density and biodiversity were highest in summer and lowest in winter. The mean biomass of macroinvertebrates was 20.8 ± 6.1 g/m^2. Biomass changed seasonally in the same way as density, with the change in biomass being： summer （Aug.） 〉autumn （Oct.） 〉spring （Apr.） 〉 winter （Dec.）. A BIO-ENV analysis showed that the mean grain size of sediment, height of Spartina and salinity were the ma- jor factors which affected the structure of the macroinvertebrate community. Variations in the community structure were probably caused by the population dynamics of S. alterniflora along with the variation in sampling time and location.
