Community structure of macrobenthos in coastal water off Rushan, southern Shandong Peninsula, and the relationships with environmental factors

To understand the present actuality of the marine ecosystem in the southern coastal water region of the Shandong Peninsula and the impact of the global change and the human activities to the marine ecosystem of the region, the macrobenthic community structure was researched based on data from 26 sampling stations carried out on four seasonal cruises from December 2006 to November 2007. The data was analyzed using PRIMER 6.0 and SPSS 15.0 software packages. The results showed that 236 macrobenthic species in total were collected from the research region by the field works. Most of the species belong to Polychaeta （76 species）, Mollusca （75） and Crustacea （60）. Of which, 33 species were common species by the four cruises. The dominant species were different among the four seasons, however, the polychaete species Nephtys oligobranchia and Sternaspis scutata were always dominant in the four seasons. The abundances and biomasses of the macrobenthos from the research region were variable in the four seasons. The results of CLUSTER and MDS analysis showed that the similarities of macrobenthic structures among the stations were low, most of the similarities were at about 40% of similarity values, only that of two stations were up to 60%. In accordance with the similarity values of the macrobenthic structures, the 26 stations were clustered as six groups at arbitrary similarity level of 30%. The ABC curve indicated that the marcofauna communities in the research region had not been disturbed distinctly. The results of BIOENV and BVSTEP （Spearman） analysis implied that the concentrations of organic matter in bottom water and heavy metal copper in sediment, water depth and temperature of bottom were the most significant environmental factors to affect the macrobentic community.

Spatial and seasonal distribution of intertidal macrobenthos with their biomass and functional feeding guilds in the Naf River estuary, Bangladesh

The Naf River estuary is one of the most productive ecological ecosystems in Bangladesh providing an important feeding area for fishes and other aquatic animals.However,detailed information on macrobenthic communities is rarely available in this area.Our study focused on the seasonal and spatial variability of macrobenthic community structure with their biomass and functional guilds.In total,fortyseven taxa were identified under nine major groups and seven functional feeding guilds.Among macrobenthic taxa,Polychaeta was dominant in both seasons and all over the estuary contributing 60%of total benthos.The mean abundance of macrobenthos was higher during the pre-monsoon(2 972±1 994 inds./m^2)than the monsoon(1 572±361 inds./m^2)being maximum at mid-estuary region and minimum at upper and lower estuary regions.Of the diversity indices,density(P=0.01,P=0.003),the number of taxa(P=0.000 3,P=0.000 9)and Margalef′s Index(P=0.000 4,P=0.001)of macrobenthos were significantly different among stations and seasons.Shannon-Weiner index(P=0.009,P=0.12)and Pielou’s evenness index(P=0.03,P=0.14)had significant differences among stations but not among seasons.Cluster analysis suggested that distribution of macrofauna is strongly influenced by seasonality.Among the feeding types,carnivorous were found to be dominant at the upper and mid-estuarine regions,and herbivorous were at lower estuarine regions.Carnivorous species were dominant in both seasons.Omnivores have shown to be the most abundant feeding type in terms of biomass though herbivores were highest during monsoon.

Community structure and spatial distribution of macrobenthos in the shelf area of the Bering Sea

Field investigations of marine macrobenthos were conducted at ten sites in the Bering Sea in July 2010. Altogether 90 species of macrobenthos belonging to 59 families and 78 genera were identified. Among them, 41 polychaetes, 16 mollusks, 23 crustaceans, three echinoderms, two cnidarians, one nemertean, one priapulid, two sipunculids, and one echiuran were identified. The average density and biomass of total macrobenthos were 984 ind./m2 and 1207.1 g/ma of wet weight, respectively. The predominant species in the study area were Scoloplos armiger, Eudorella pacifica, Ophiura sarsii, Heteromastus filiformis, Ennucula tenuis, and Harpiniopsis vadiculus by abundance, while the predominant species in this area was Echinarachnius parma by biomass. Hierarchical cluster analysis （Bray-Curtis similarity measure） revealed that two impor- tant benthic assemblages in the study area were CommunityA and Community B. CommunityA was stable and Community B was unstable, as shown by the Abundance/Biomass Comparisons （ABC） approach. The macrobenthic community structure in the shelf of the Bering Sea was characterized by its high abundance and biomass, high productivity but great heterogeneity.

Biodiversity and community structural characteristics of macrobenthos in the Chukchi Sea

Field sampling of the macrobenthos from 23 stations in the Chukchi Sea was conducted during the 4th CHI- NARE （Chinese National Arctic Research Expeditions, July-August, 2010）. We identified a total of 140 species of macrozoobenthos belonging to nine phyla, which were dominated by polychaetes （66）, crustaceans （30）, and mollusks （25）, followed by echinoderms （9） and others （ten others, including four cnidarians, one oligochaete, one sipuncula, one priapulida, two bryozoans, and one urochordata）. The dominant species were Aphelochaeta pacifica, Heteromastus filiformis, Nephtys ciliata, Nephtys caeca, Scoletoma fragilis, Golfingia margaritacea, Nuculana pernula, Macoma calcarea, Ennucula tenuis, Macoma inquinata, Musculus discors, Echinarachnius parma, and Ophiura sarsii, so there were more cold-eurythermal boreal immigrants than trulyArctic species （endemics）. The average density and biomass （mean ± SD across all stations） of the total macrozoobenthos were （916 ± 907） ind/m2 and （902.9 ± 1227.7） g/m2 （wet weight）, respectively. Relatively high density and biomass were observed in the samples from the northeastern and southern Chukchi Sea. The spatial variation of benthic communities in the study sea area was relatively large; this spatial heteroge- neity has led to high diversity and a patchy distribution pattern in the community structure. Compared to the 1st CHINARE （July-August, 1999）, this investigation revealed different degrees of decreases in the average taxa numbers and the average density, abundance, and biodiversity in the area over the recent decade, which might be associated with global warming, human activities, and sea ice variations.

Macrobenthos monitoring in the Gulf of Suez,Egypt

The biogeography of macrobenthic communities with large-scale differences in species distribution and abundance was studied along the eastern and western coastal regions of the Gulf of Suez to indicate biodiversity of benthos in relation to the prevailing environmental conditions. In general, benthos have a wide variety of species of mainly polychaet worms, crustaceans, bivalves, and other bottom invertebrates living in burrows in/or on the sediment surface. Coastal development clearly affects the ecosystem after the construction of coastal projects. The highest values of benthic diversity, evenness, richness and dominance are found at the Gulf of Suez （WG 1, WG 3）, Ras Gharib （WG 7, WG 8） and Ras Shukier （WG 9a） by contrast to others. The abundance of macrobenthic organsims along the coasts of Gulf of Suez can be arranged in the following sequence： other groups （34%） greater than crustaceans （25%） greater than polychaetes （22%） greater than molluscs （17%） greater than echinoderms （2%）. The biomass of benthic assemblages at different sampling sites can also be ranked as follows： echinoderms （52%） greater than molluscs （27%） greater than crustaceans （16%） greater than polychaetes （2%） greater than other groups （3%）. Some benthic groups or species indicated a distinctive correlation to pollution sources in the marine ecosystem which obviously increased in the coastal areas due to the extension of the coastal development. These activities needed regular information to establish database for the biology and distribution of marine benthic communities. The density and diversity of benthos are significantly affected by eutrophication at Ain Sukhna, whereas the benthos in the open Gulf of Suez do not seem to be adversely affected by pollution.

Community characteristics of macrobenthos in the Huanghe(Yellow River) Estuary during water and sediment discharge regulation

The community characteristics of macrobenthos in the Huanghe（Yellow River） Estuary is influenced by a combination of natural and anthropogenic factors. Here, we investigated short-term changes（1-month） in macrobenthic community structure in response to water and sediment discharge regulation（WSDR） in 2011.Specifically, we sampled the macrobenthos at 18 sampling stations situated at four distances（5, 10, 20, and 40 km）from the mouth of the Huanghe Estuary before（mid-June）, during（early-July）, and after（mid-July） WSDR. The results showed that a total of 73, 72, and 85 species were collected before, during, and after WSDR, respectively.Then, 13, 1, and 16 dominant species were detected at this three periods. Four phyla were primarily detected at all three periods（Annelida, Mollusca, Arthropoda, and Echinodermata）. However, while Mollusca and Annelida were the most important phyla in our study, Echinodermata and Annelida were the most important phyla in 1982,demonstrating major changes to community structure over a 3-decadal period. All stations were of high quality BOPA index before WSDR, whereas two and three stations were of reduced quality BOPA index during and after WSDR, respectively. The results of ABC curves showed that had incurred disturbed conditions after human activities WSDR. Most important of all, multivariate analyses and RDA analysis indicated that the structure of the macrobenthic community was closely linked to environment factors, including that organic content factor caused the distribution of macrobenthic community mostly during WSDR, while water depth after WSDR affected the macro benthos community structure seriously, and during WSDR, the environment factor influencing it was not single, including organic content, sulfide content, Hg and As. These differences may have been due to changes in water transparency negatively impacting the growth and development of macrobenthos, due to specific lifehistory requirements. Our results demonstrate that anthropogenic activity is having both long-term（3 decadal）and short term（1-month） impacts on the structure of the macrobenthic community of the Huanghe Estuary. In conclusion, human activities WSDR influence the habitat environment of macro benthos, including the water temperature, nutrients, bioturbation, and so on. Therefore, we suggest the necessity to strengthen regulations of land-derived organic pollutant input to maintain the ecological balance of the Huanghe Estuary.

Gorgan Bay： a microcosm for study on macrobenthos speciesenvironment relationships in the southeastern Caspian Sea

The relationship between spatial patterns of macrobenthos community characteristics and environmental conditions（salinity, temperature, dissolved oxygen, organic matter content, sand, silt and clay） was investigated throughout the Gorgan Bay in June 2010. Principal components analysis（PCA） based on environmental data separated eastern and western stations. The maximum（4 500 ind./m2） and minimum（411 ind./m2） densities were observed at Stas 1 and 6, respectively. Polychaeta was the major group and Streblospio gynobranchiata was dominant species in the bay. According to Distance Based Linear Models results, macrofaunal total density was correlated with silt percentage and salinity and these two factors explaining 64% of the variability while macrofaunal community structure just correlated with salinity（22% total variation）. In general, western part of the bay showed the highest number of species and biodiversity while, the highest density was found at Sta. 1 and in the middle part of the bay. Furthermore, relationship between diversity indices and macrobenthic species with measured factors is also discussed. Our results confirm the effect of salinity as an important factor on distribution of macrobenthic fauna in south Caspian brackish waters.

Notes Ecological study of macrobenthos in Fuqing Bay

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Distribution pattern of macrobenthic assemblages along a salinity gradient in the Hangzhou Bay and its adjacent waters

It is widely acknowledged that the distribution of macrobenthos is affected by salinity, but the degree of influence varies in different areas. To explore the distribution pattern of macrobenthic assemblages in the Hangzhou Bay,12 stations were sampled to collect macrobenthos and the corresponding bottom water. Changes in the general characteristics of macrobenthos along the salinity gradient in the Hangzhou Bay and its adjacent waters were considered. Three dominant species were identified, including the polychaetes Sternaspis chinensis, the crustacea Oratosquilla oratoria and the echinoderm Ophiuroglypha kinbergi. And the macrobenthic assemblages showed a zonal distribution along with the salinity change. The correlation analyses showed that salinity, depth,temperature, suspended solids and dissolved oxygen had concurrent significant correlations with carnivorous group, Margalef species richness(d), Brillouin index(H) and Shannon-Wiener diversity index(H'). In light of the strong correlation between salinity and Changjiang River diluted water, which produces considerable disturbances by freshwater inflows, the deposition of suspended solids and the resuspension of seabed sediments,the combined environmental disturbances, instead of salinity alone, should be adopted to explain the zonation distribution pattern of macrobenthic assemblages.

Macrobenthic community structure in the Changjiang Estuary and its adjacent waters in summer

On the basis of data collected in the summer of 2006 from 27 sampling stations in the Changjiang Estuary and its adjacent waters, the ecological characteristics of macrobenthos and the relationship between the macrobenthos and the environmental factors were studied using hierarchical cluster and non-metric multidimensional scaling （MDS）. The biomass, abundance, Shannon -Wiener＇s and Margalef＇ s indices of the macrobenthos were presented. The results showed that a total of 253 macrobenthic species were found in the research region, and most of them belong to mollusks and polychaetes. The dominant species were Cossurella dimorpha, Eocylichna cylindrella, Episiphon kiaochowwanense, Nassarius semiplicatus, Ocstergrenia variabilis and Sternaspis scutata. The average abundance of the macrobenthos was （313. 15 ±233.4） ind./m^2, and the average biomass was （ 15. 2 ± 11.2 ）g/m^2. The distribution patterns of the abundance and biomass of the macrobenthos were similar. The abundance and biomass in the area close to the estuary were lower than those from the area more distant to the estuary; the central part of the research region had higher abundance and biomass than other parts of the research region. In accordance with the results, four macrobenthic communities with distinct spatial differences were identified. The low abundance and biomass in the area close to the estuary should be caused by the high sedimentation rate. The statistical analysis indicated that the depth is the most important factor affecting the distribution of macrobenthos.

A comparison of the applicability of the Shannon-Wiener index,AMBI and M-AMBI indices for assessing benthic habitat health in the Huanghe(Yellow River) Estuary and adjacent areas

From a dataset of macrobenthos obtained from 18 cruises from 2004 to 2013 in the Huanghe（Yellow River）Estuary and its adjacent areas,the composition and characteristics of macrobenthos were analyzed,and the applicability of the Shannon-Wiener Index（H′）,AZTI＇s Marine Biotic Index（AMBI） and multivariate AMBI（MAMBI） for assessing benthic habitat quality was compared.The results showed a total of 203 macrobenthos in the study area.The macrobenthos were dominated by polychaetes,followed by mollusks and crustaceans.The macrobenthic ecological groups were dominated by EGI,EGII and EGIII,which respectively accounted for 31.5%,36.0% and 21.2% of the total.There were significant differences between the evaluation results of the three indices.The ecological quality status（EQS） levels given by the AMBI were greater than those given by the H′ and M-AMBI.The AMBI could not reflect the differences between 11 sites but the H′ and M-AMBI could do.Moreover,the three indices responded well to the variations in salinity（S） and dissolved oxygen（DO） in the waters.The H′ and MAMBI also responded sensitively to the differences in physical parameters,such as water depth and sediment texture.The correlation between M-AMBI and environmental pressure gradient data was the strongest.The MAMBI could effectively distinguish degraded conditions from undegraded but the H′ and AMBI could not.Therefore,the M-AMBI reflected benthic habitat health well in the study areas.However,the objectivity of evaluation results of M-AMBI needs further verification by physical,chemical and biological methods.The thresholds also need further discussion.

Assessing benthic habitat quality using biotic indices in the Laizhou Bay, China

As an important part of the Bohai economic rim,the Laizhou Bay has been stressed by serious eco-environmental problems in recent years.In this study,the Shannon-Wiener index(H′),AZTI’s marine biotic index(AMBI)and the multivariate AMBI(M-AMBI)were used to assess the ecological quality status(EQS)of the Laizhou Bay according to macrobenthos data collected annually in August 2011–2014.The results showed that the overall benthic habitat quality in the Laizhou Bay was assessed as“Good”.However,25%of the samples were classified as“Moderate”,“Bad”or“Poor”status under degraded conditions.Ecological group III(EGIII)species which had a certain tolerance to environmental disturbances had a higher proportion in each station,and most of them had appeared the pollution indicator species Capitella capitata.This indicated that the benthic habitat in the Laizhou Bay had been disturbed and polluted to some extent.The comparison of the three indices evaluation result and the RDA analysis showed that the H′and M-AMBI were more suitable when the relative abundance of the single species was high and the macrobenthic community was significantly imbalanced;when the relative abundance of opportunistic species(EGIV and EGV)was high,the AMBI and M-AMBI could reflected the EQS objectively;in an undisturbed and polluted environment,all the three indices could indicate the benthic habitats quality.In summary,the better correlation between the three indices and environmental factors showed that they were well responsive to the tendency of the benthic habitats quality in the Laizhou Bay.

The influence of water-sediment regulation on macrobenthic community structures in the Huanghe River(Yellow River)Estuary during 2012–2016

To determine if water-sediment regulation has affected macrobenthic community structure in the Huanghe River Estuary,China,macrobenthic samples were collected following regulation events from 2012 to 2016.We identify seven phyla and 138 macrobenthic species from within samples throughout the survey area,over time.Species richness and abundance in 2012 were significantly higher than in 2016.Biomass did not differ significantly during 2012–2016.Dominant species were mostly small polychaetes,with mollusks,arthropods,and echinoderms all being relatively rare.In 2016,dominant species were small polychaetes.MDS reveals macrobenthic communities at all surveyed distances from the estuary to have become the same community structure over time.Shannon-Wiener diversity and Margalef richness indexes trended down over time.CCA reveals the most dominant sediment-dwelling species to prefer lower dissolved oxygen,sulfides,and pH,and sediments with high D50 and low clay content.We speculate that water-sediment regulation has affected seabed communities,particularly Region A in our survey area.

Biodiversity and seasonal variation of benthic macrofauna in Minicoy Island, Lakshadweep,India

From the Indian coast only limited data are available on the benthic fauna of the seagrass communities. In this study, seasonal variation in the distribution of macrobenthos and influence of environmental parameters was explored at four seagrass beds and two mangrove stations along the Minicoy Island, Lakshadweep, India, from September 1999 to August 2001. A total of 160 macrobenthic species from eight major groups represented the macrofauna of the Minicoy Island. Of the identified taxa, molluscs 70（gastropods 41.46%, bivalves 7.5%）, polychaetes 27（16.88%）, crustaceans 30（18.75%）, echinoderms 11（6.88%） and remaining others. Average seasonal abundance of benthic macrofauna ranged from 219 to 711 ind./m2, species diversity varied from 1.45 to 3.64 bits per individual, species richness index ranged from 4.01 to 26.17, evenness 0.69 to 1.66. In general, the higher abundance and species diversity was noticed in southern seagrass stations and northern seagrass stations, but in the mangrove stations comparatively low species diversity was observed. Three-way analysis of variance indicated that all communities resulted as being significantly different between seagrass and mangrove station, mainly when the seasonal interaction was considered. Multivariate analyses were employed to help define benthic characteristic and the relationship between environmental parameters at the six monitoring stations. Results of cluster analyses and multidimensional scale plot suggest that for mangrove region, different physiographic provinces, lower salinity, dissolved oxygen and sediment biotic structure have a higher influence on the species composition and diversity than other oceanographic conditions.

Spatial pattern of macrobenthic communities along a shelf-slope-basin transect across the Bering Sea

Due to its unique geological location, the Bering Sea is an ideal place to investigate the water exchange and ecosystem connectivity of the Pacific Ocean–Arctic Ocean and subarctic–Arctic region. Based on a number of summer surveys（July to September, 2010, 2012 and 2014）, macrobenthic communities and their spatial-temporal patterns are exhibited for the majority of the Bering Sea（53°59′–64°36′N）. The results show that the macrobenthic communities were dominated by northern cold-water species and immigrant eurythermic species, and the communities assumed a dispersed and patchy distribution pattern. Polychaetes（Scoloplos armiger）, crustaceans（Ceradocus capensis） and sea urchins（Echinarachnius parma） were the main dominant groups in the shallow shelves; the sea star（Ctenodiscus crispatus） and the brittle star（Ophiura sarsii） were the main dominant groups in the continental slope; whereas small polychaetes（Prionospio malmgreni） dominated the basin area. Sediment type, water depth, and currents were the major factors affecting the structure and spatial distribution of the macrobenthic communities. Compared with other seas, the shallow areas of the Bering Sea showed an extremely high-standing biomass. In particular, the northern shelf area（north of St. Lawrence Islands and west of 170°W）,which is primarily controlled by Anadyr Water, is an undersea oasis. In contrast, a deficiency in the downward transport of particulate organic carbon has resulted in a desert-like seabed in the basin area. By comparing our results to previous studies, we found that macrobenthic communities of the Bering Sea have undergone significant structural changes in recent decades, resulting in a decrease in abundance and an increase in biomass.In addition, populations of amphipods and bivalves in the northern shelves have decreased significantly and have been gradually replaced by other species. These changes might be associated with advanced seasonal ice melting,changes in organic carbon input, and global warming, indicating that large-scale ecosystem changes have been occurring in the Bering Sea.

Macrobenthic assemblage characteristics under stressed waters and ecological health assessment using AMBI and M-AMBI:a case study at the Xin'an River Estuary,Yantai,China

To understand the ecological status and macrobenthic assemblages of the Xin＇an River Estuary and its adjacent waters, a survey was conducted for environmental variables and macrobenthic assemblage structure in September 2012（Yantai, China）. Several methods are adopted in the data analysis process： dominance index,diversity indices, cluster analysis, non-metric multi-dimentional scaling ordination, AMBI and M-AMBI. The dissolved inorganic nitrogen and soluble reactive phosphorus of six out of eight sampling stations were in a good condition with low concentration. The average value of DO（（2.89±0.60） mg/L） and p H（4.28±0.43） indicated that the research area faced with the risk of ocean acidification and underlying hypoxia. A total of 62 species were identified, of which the dominant species group was polychaetes. The average abundance and biomass was577.50 ind./m^2 and 6.01 g/m^2, respectively. Compared with historical data, the macrobenthic assemblage structure at waters around the Xin＇an River Estuary was in a relatively stable status from 2009 to 2012.Contaminant indicator species Capitella capitata appeared at Sta. Y1, indicating the animals here suffered from hypoxia and acidification. AMBI and M-AMBI results showed that most sampling stations were slightly disturbed,which were coincided with the abiotic measurement on evaluating the health conditions. Macrobenthic communities suffered pressures from ocean acidification and hypoxia at the research waters, particularly those at Stas Y1, Y2 and Y5, which displays negative results in benthic health evaluation.

Effects of Multi-Stage Flash and Reverse Osmosis Desalinations on Benthic Assemblages in Bahrain,Arabian Gulf

Marine environment of the Arabian Gulf is naturally stressed due to marked fluctuations in sea temperatures and high salinities. Anthropogenically induced stresses including waste water discharges from desalination plants could pose additional threats to the coastal and marine ecosystems in the Arabian Gulf. Macrobenthic assemblages in the proximity of two major desalination plants that use Multi-Stage Flash (MSF) and brackish water Reverse Osmosis (RO) technologies in Bahrain were investigated. Reduced levels of biodiversity and abundance were recorded in sampling stations adjacent to the outlet of MSF reflecting severe impacts on macrobenthic assemblages caused by brine effluents that associated with high temperatures, salinities, and a range of chemical and heavy metal pollutants. Although localized severe impacts on macrobenthic assemblages were detected, collective discharges of desalination effluents, may synergistically contribute to the degradation of the naturally stressed marine ecosystems and natural resources in the Arabian Gulf.

THE ENVIRONMENTAL QUALITY OF THE SEWAGEDISCHARGE AREA OF QINGDAO COVE--ACLADISTIC ANALYSIS

This study on the environmental quality of the Qingdao Cove intertidal zone sewage discharge area is based on data obtained from the December of 1989 and 1990 macrobenthos investigations there, and uses pollution indicator species and computer aided cladistic analysis to divide the area into a polluted area and a semi-polluted area. The study showed the environmental quality in 1990 improved over that in 1989.

Assessment of macrobenthic community function and ecological quality after reclamation in the Changjiang(Yangtze)River Estuary wetland

An ecological optimization project(semi-closed reclamation project)was implemented to control the invasion of Spartina alterniflora,and optimize the habitat of the Chongming Dongtan wetland,in the Changjiang(Yangtze)River Estuary.After project implementation,a macrobenthic ecological survey was conducted in a natural tidal flat and a semi-closed reclamation restoration area within the Chongming Dongtan wetland from 2019 to 2020.Compared with historical data before reclamation,findings showed that the groups,numbers,and species diversity of the macrobenthos increased significantly,and the ecological optimization project resulted in good ecological benefits.In addition,compared to the natural tidal flat,the number of collected macrobenthic phyla,and the macrobenthic density and biomass were significantly lower in the restoration area.Furthermore,the biodiversity index and functional redundancy of natural tidal flats were generally higher,indicating that the community composition and function of natural tidal flats were relatively more stable.Even though the species composition differed between a number of restoration areas and natural tidal flats,there was no difference in functional diversity,indicating that the effect of restoring ecological functions in restoration areas was optimal.Among them,the biodiversity and functional redundancy of Site S2 were significantly reduced,and the ecosystem function was extremely unstable.Habitat heterogeneity,vegetation community and decreasing salinity were the main factors that affected the ecological functions of macrobenthos.The ecological quality was also evaluated;the Transects N3 and N4 showed good quality.The overall ecological quality of the restoration area was generally high,but that of Site S2 was poor and that of Site S2E was merely good,which was mainly due to modifications of the ecological function of macrobenthos.It is suggested that reeds mowing and freshwater species release should be adopted in restoration areas to improve the community function and the environmental disturbance resistance of the macrobenthos.

Responses of macrobenthic communities to patchy distributions of heavy metals and petroleum hydrocarbons in sediments:A study in China's Zhoushan Archipelago

This study conducted four cruises during 2014–2017 to investigate relationships between macrobenthic communities and sediment contaminations in sea area around the Zhoushan Archipelago.Fourteen sites were categorized into three groups:high total heavy metal contamination content(HHMC),high total petroleum hydrocarbon content(HTPH),and low content ratio of heavy metal contamination content to total petroleum hydrocarbon content(HMC/TPH)areas.Four main taxa of macrofauna(polychaetes,bivalves,gastropods,and crustaceans)were determined to respond to environmental factors differently.While tolerant polychaetes being the minimal impact by environmental factors,bivalves were threated by heavy metal pollutions in sediment.Additionally,body size distribution frequency demonstrated that macrofauna in the low HMC/TPH areas were less disturbed by contamination than those in the HHMC and HTPH areas.The result represented the presentation of sensitive species while tolerant species are usually considered as small size organisms.Overall,this study confirmed the hypothesis that the contamination levels of small-scale patches is indicated by the condition of macrobenthic communities.