钦州湾大型底栖动物生态学研究

通过2008年~2009年在钦州湾及附近海域进行的4个航次的大型底栖动物调查,共获大型底栖动物8门62科94种,软体类最多,其次为多毛类,种类季节变化较大。以优势度指数Y>0.02为判别标准,调查区春季优势种为方格皱纹蛤（Periglypta lacerata (Hanley)）、刺足掘沙蟹（Scalopidia spinosipes Stimpsom）和独齿围沙蚕（Perinereis cultrifera Grube）,夏季优势种为方格皱纹蛤、刺足掘沙蟹和持真节虫,秋季优势种为曲波皱纹蛤和网纹藤壶,冬季优势种为肋鲳螺和方格皱纹蛤。春、夏季优势种变化不大,秋、冬季优势种变化较大,除方格皱纹蛤外均为季节特有种。海区底栖生物平均总密度和平均总生物量分别为439ind./m2和115.14g/m2。与20世纪80年代钦州湾茅尾海调查结果相比,平均栖息密度有所升高,但是平均生物量却有较大程度的降低。底栖动物群落的丰富度指数（D）、Shannon-Wiener多样性指数（H′）和均匀度指数（J′）平均值分别为4.01、1.80和0.73,水平不高。用SPSS软件将各站大型底栖动物的平均密度、平均生物量、多样性指数等生态特征值与水深等理化因子进行了Pearson相关分析,结果表明春季各特征指数与环境因子相关性不显著;夏季丰度、多样性指数和均匀度指数均与水深呈显著负相关,种类数、丰富度和多样性指数与沉积物pH呈显著负相关;秋季密度与硫化物呈显著正相关;冬季生物量与硫化物和有机质均呈显著正相关。     

2011-2020年长江口大型底栖动物群落结构变化趋势

对2011—2020年夏季长江口48个站位的大型底栖动物定量监测数据进行统计分析,研究长江口海域底栖生物群落时空结构演变特征。结果表明,近10年长江口海域共鉴定大型底栖动物284种,其中多毛类128种,占总种数的45.1%,甲壳类64种占22.2%,软体动物56种占19.7%,棘皮动物16种占5.6%,其他类合计20种。平均生物密度为(79.5±45.9)个/m²(年份变幅14.7—195个/m²)。平均生物量为(5.20±3.25)g/m²(年份变幅1.01—10.11g/m²),多毛类、软体动物、甲壳类是生物密度和生物量组成的主要类群。十年期间种类数、生物密度和生物量均呈现明显上升趋势,口外区贡献最突出。四个监测区域(南支、北支、杭州湾、口外)的优势种差异大。丝异须虫Heteromastus filiformis在各年份的优势种中出现的频度显著最大。总体来看,长江口监测区域大型底栖动物群落自然演变趋势向好。三项多样性指数统计结果表明,口外区大型底栖动物种类组成多样性水平显著高于口内三个区。生物群...     

The species composition and pattern of distribution of hermit crabs (Decapoda: Paguroidea) in Vostok Bay,Sea of Japan

The species composition, abundance, and vertical distribution of hermit crabs (Decapoda: Paguroidea) were investigated in Vostok Bay, Sea of Japan, from September 2014 to September 2015. A total of seven species from two families were found in the monitoring area of approximately 5000 m² located on the bottom within a depth range of 0–11 m: Pagurus minutus, P. proximus, P. brachiomastus, P. pectinatus, P. ochotensis, P. middendorffii (Paguridae), and Areopaguristes hirsutimanus (Diogenidae). Their population density varied from 22 ± 13 to 26 ± 2 ind./m²; the biomass varied from 55.76 ± 26.10 to 93.38 ± 27.00 g/m². The species composition remained invariable throughout the study period. The proportions of species abundance changed between seasons, as this parameter is largely determined by seasonal migrations of hermit crabs. Pagurus minutus predominated in number in winter and spring (up to 71%); P. proximus, in summer and autumn (up to 47%). In autumn and spring, P. ochotensis and P. pectinatus constituted a major part of biomass (18–25% and 19–20%, respectively). The proportion of a previously abundant species, P. middendorffii, was very small (no larger than 1.3%) during the study period. Another four species of hermit crabs occurred in other parts of Vostok Bay; thus, the fauna of the bay currently includes 11 species of this group.     

Predominance of phytoplankton-derived dissolved and particulate organic carbon in a highly eutrophic tropical coastal embayment (Guanabara Bay,Rio de Janeiro,Brazil)

We investigate the carbon dynamics in Guanabara Bay, an eutrophic tropical coastal embayment surrounded by the megacity of Rio de Janeiro (southeast coast of Brazil). Nine sampling campaigns were conducted for dissolved, particulate and total organic carbon (DOC, POC and TOC), dissolved inorganic carbon (DIC), partial pressure of CO₂ (pCO₂), chlorophyll a (Chl a), pheo-pigments and ancillary parameters. Highest DOC, POC and Chl a concentrations were found in confined-shallow regions of the bay during the summer period with strong pCO₂ undersaturation, and DOC reached 82 mg L^?1, POC 152 mg L^?1, and Chl a 800 μg L^?1. Spatially and temporally, POC and DOC concentrations varied positively with total pigments, and negatively with DIC. Strong linear correlations between these parameters indicate that the production of TOC translates to an equivalent uptake in DIC, with 85% of the POC and about 50% of the DOC being of phytoplanktonic origin. Despite the shallow depths of the bay, surface waters were enriched in POC and DOC relative to bottom waters in periods of high thermohaline stratification. The seasonal accumulation of phytoplankton-derived TOC in the surface waters reached about 105 g C m^?2 year^?1, representing between 8 and 40% of the net primary production. The calculated turnover time of organic carbon was 117 and 34 days during winter and summer, respectively. Our results indicate that eutrophication of coastal bays in the tropics can generate large stocks of planktonic biomass and detrital organic carbon which are permanently being produced and partially degraded and buried in sediments.     

Bacterial Abundance and the Activity of Microbiological Processes in the Bay of Tugur of the Sea of Okhotsk

This paper presents the results of investigation of the total abundance and the biomass of bacterioplankton, the abundance of heterotrophic bacteria, and the activity of microbiological processes involved in the carbon cycle in the water of the Bay of Tugur of the Sea of Okhotsk. In different regions of the bay, the total abundance of bacterioplankton was found to vary from 0.51 × 10⁶ to 2.54 × 10⁶ cells/ml; the bacterioplankton biomass, from 8.5 to 46.5 g C/l; the abundance of heterotrophic bacteria, from 0.06 × 10³ to 2.12 × 10³ cells/ml; the bacterial assimilation of CO₂, glucose, acetate, and protein hydrolysate, from 0.8 to 6.3, from 0.11 to 1.88, from 0.07 to 0.56, and from 0.01 to 0.22 mg C/(m³ day), respectively; the degradation of organic matter ranged from 28 to 221 mg C/(m³ day); and the intensity of methane oxidation, from 0.0005 to 0.17 l CH₄/l. The spatial pattern and the functional characteristics of bacterioplankton in the Bay of Tugur were found to be dependent on the tidal dynamics.     

Peculiarities of summer phytoplankton spatial distribution in Onega Bay of the White Sea under local hydrophysical conditions

The species composition and phytoplankton biomass, concentrations of chlorophyll “a” (Chl) and nutrients in the surface water layer, and accompanying hydrophysical conditions were studied in Onega Bay of the White Sea in June 2015. The temperature and salinity of surface water layer and the water column stability varied greatly in the bay. The nutrients' concentrations exceeded the limiting threshold necessary for the phytoplankton development. The phytoplankton abundance was relatively low, averaged as 13.46 ± 9.00 mg C/m³ (total phytoplankton biomass), 0.78 ± 0.43 mg/m³ (concentration of chlorophyll “a”), and 0.18 ± 0.27 mg C/m³ (picophytoplankton biomass). The highest phytoplankton biomass has been registered along the frontal zones. Three phytoplankton communities that differed significantly in their structure have been found.     

Soil microarthropods and macrofauna in monsoon tropical forests of Cat Tien and Bi Dup-Nui Ba National Parks,southern Vietnam

The abundance, biomass, vertical distribution, and taxonomic composition of soil invertebrates (springtails, macrofauna, and termites) were studied in forest formations differing in edaphic and climatic conditions: lowland forests dominated by Lagerstroemia spp. or Dipterocarpus spp. in the Cat Tien National Park and in a mountain pine (Pinus kesiya) forest on the Da Lat Plateau, southern Vietnam. In the lowland forests, springtails had a relatively low density (10000–12000 ind./m²), but their diversity was high (41–43 species in each forest). The density of large soil invertebrates (without ants and termites) reached 500–700 ind./m² at a biomass of approximately 30 g/m² (with earthworms accounting for up to 230 ind./m² and 19–28 g/m²). Among termites, species of the genera Macrotermes and Odontotermes were dominant. Their total biomass in some areas exceeded 15–20 g/m². In the mountain pine forest, the total biomass of soil macrofauna was approximately 11 g/m², the abundance and diversity of springtails were low (7500 ind./m², 28 species), and wood-destroying species of the genera Schedorhinotermes sp. and Coptotermes sp. dominated among termites.     

Distribution patterns in the biomass of macrozoobenthic communities in Admiralty Bay (King George Island, South Shetlands, Antarctic)

The distribution patterns of macrozoobenthic communities as shown by the biomass of the higher taxa were investigated in Admiralty Bay. Material was collected at depths ranging from 4 to 500 m (102 quantitative samples), representing the full depth range of this basin and including areas characterized by the different levels of glacial influence. Five community groups were distinguished by multivariate analysis (clustering, MDS) based on the Bray--Curtis similarity index. In the Ezcurra Inlet, the area characterized by intensive glacial processes resulting in a high sedimentation rate, the distribution of biomass was not depth related, but was associated with the intensity of glacial disturbance along the axis of the fjord. The innermost part of this fjord, which receives strong outflows from glaciers, had a low biomass value (2.9 g/0.1 m²) and was dominated by polychaetes. The middle part of the fjord which is not so heavily disturbed had higher biomass values (46.1 g/0.1 m²) due to the dominance of bivalves. A clear depth gradient of biomass distribution was observed in bottom areas located far from glaciers, in the central basin of the bay, with three zones within the depth ranges 4–30, 40–380, and 400–500 m. The highest mean biomass values (92.5 g/0.1 m²) were found in the middle sublittoral (40–380 m) dominated by ascidians. In the shallow and deep assemblages, the biomass was lower (33.8 g/0.1 and 30.9 g/0.1 m² respectively), most probably associated with the ice disturbance in the shallows and lower food supply in the deepest part of the shelf.     

The Impact of Artisanal Fishery on a Tropical Intertidal Benthic Fish Community

We examined the benthic fishes and artisanal fishery in the intertidal flats of Inhaca Island, Mozambique. Results of a questionnaire indicated that catches had decreased, and that piscivorous fish have disappeared. Results of a catch sampling study indicated that current catch rates are low, < 2 kg person^–1 fishing trip^–1. Use of fishing gear was significantly related to season, diel and lunar tidal phase, and habitat. Forty-eight fish species were observed in the catches with eight species comprising 80% of the catch of 1814 specimens. The annual catch was estimated at 26.2t for the whole bay. Highest fishing pressure was observed in the central section of the bay. A demersal fish survey was carried out with a 2-m beam trawl to sample the fish community. Two different areas were sampled, one area with a low, and one with a high fishing pressure. A total of 19889 fishes were caught comprising 93 species. Gobies dominated the catches and accounted for 56% of all specimens. Fishes were small with a mean standard length of 29mm. The Saco area exhibited the highest catch rates and biomass (maximum of 1040 fish 1000 m^–2 and 1490g 1000 m^–2), and the highest species richness and evenness values. Catch composition was different between the two sampling areas, and was strongly affected by season, but less by habitat. Total fish biomass was estimated at 5.6t for the whole area. Stomach content varied with habitat, and season, and was dominated by benthic invertebrates. The largest estimates of consumption were obtained in the tidal channel and the Zostera beds. Mean consumption of benthic organisms was 1.3g AFDW m^–2 yr^–1. The area seemed to be overfished. The heavily fished areas exhibited lower catch rates, lower proportion of piscivorous fish, increased proportion of small fish, and a decrease in species diversity.     

Abundance and biomass estimates of the benthic fauna in Admiralty Bay,King George Island,South Shetland Islands

Summary Quantitative benthic samples were collected along three transects in Admiralty Bay, King George Island, South Shetlands. At each of a total of 18 stations, between 15 and 250 m depth, we took 3 replicate samples with a van Veen grab. Animals collected were classed into major groups. Abundance and biomass per m² was calculated for each sampling site. Considerable population densities and high biomass values were found. Most abundant groups were Bivalvia, Polychaeta and Amphipoda, whereas the largest part of the biomass was due to Ascidiacea, Ophiuroidea, Echinoidea, Polychaeta and Bivalvia. The maximum abundance recorded was 36,000 ind m^-2 while the average was approximately 6500 ind m^-2. Maximum biomass was over 2400 g m^-2 with an average of ca. 700 g m^-2. The contribution to the total biomass by groups such as the Oligochaeta, Cumacea and Tanaidacea was higher in the inner shallow part of Admiralty Bay (Ezcurra Inlet) than in the deeper areas of the bay. Our results confirm the reports on an unusually high density and biomass of the Antarctic sublittoral benthic fauna. Sessile suspension feeders belonging to the Bivalvia, Ascidiacea, sedentary Polychaeta, and vagile scavengers of the Ophiuroidea, Amphipoda and errant Polychaeta are the most significant groups in the Antarctic Ecosystem. The total benthic biomass in Admiralty Bay, based on the present preliminary quantitative data, was estimated to be over 600,000 t. This value is probably still an underestimate.     

The benthos off King George Island (South Shetland Islands,Antarctica): further evidence for a lack of a latitudinal biomass cline in the Southern Ocean

The benthic fauna off King George Island (South Shetland Islands, Antarctica) was investigated during "Polarstern" expedition ANT XV/3 in March 1998. Samples were taken along two cross-shelf/slope transects both north (Drake Passage) and south of the island (Bransfield Strait, off Potter Cove) at water depths ranging from 130 m to 2,000 m. For a quantitative inventory, a multibox corer was used at nine stations to collect mostly infaunal macrobenthos; at seven stations, seabed photography was employed concomitantly to survey the epibenthic megafauna. Macrofauna abundances ranged from 730 ind. m^–2 at 2,000 m to >14,000 ind. m^–2 at 100 m; biomass values varied between about 50 g wet mass m^–2 (6 g ash-free dry mass m^–2) at 2,000 m and about 950 g wet mass m^–2 (about 90 g ash-free dry mass m^–2) at 200 m. Densities were dominated everywhere by polychaetes, followed by bivalves, crustaceans and ophiuroids; in terms of biomass, krill and holothurians surpassed polychaetes at some stations. No significant differences between the northern and the southern transects in total abundance and biomass were obvious. Megafauna abundances were clearly higher south of King George Island, totalling about 110–150 ind. m^–2 on the shelf (235–330 m) and about 50 ind. m^–2 at the continental slope (750 m), whereas along the northern transect they reached values of only 21–31 ind. m^–2 on the shelf (130–430 m) and decreased at the continental slope (950 m) to about 5 ind. m^–2. A brittle star, Ophionotus victoriae, strongly dominated the southern-shelf epibenthos, with relative abundances of 70–95% and a biomass of about 40–80 g wet mass m^–2 (about 4–7 g ash-free dry mass m^–2), but was numerically less important at the slope (5%) where ammotheid pycnogonids prevailed (80%). Macro- and megabenthos distribution patterns were characterized by a pronounced shelf-slope gradient – in standing stock as well as in faunistic composition – but this resemblance was statistically not significant. This finding indicates that the spatial distributions of macrobenthos and megabenthos are primarily determined by a depth-dependent factor, most probably food supply, but apparently respond differently to secondary driving forces, possibly seabed features. Our results provide further evidence for the notion that there is no distinct latitudinal gradient in benthic abundance and biomass in the Southern Ocean between the South American Magellan region and high-Antarctic waters of the Weddell Sea.     

Chitin production by Ampelisca (Amphipoda) populations from a fine sand community in the Bay of Morlaix (English channel)

We measured chitin biomass and production in five species of Ampelisca (Crustacea Amphipoda) living on a fine sand community at Pierre Noire Station in the Bay of Morlaix (Western English Channel, Brittany, France). Taking into account the maxima of their mean total production, the annual chitin production was estimated at between 600 and 900 mg m^–2 yr^–1. These values are close to those of the chitin production of pioneering benthic communities growing on naked substrates in the coastal waters of Calvi bay (Mediterranean, Corsica) between 7 to 28 meter depth, and of the zooplankton of that same area.     

Phototrophic picoeukaryotes of Onega Bay,the White Sea: Abundance and species composition

The abundance, biomass, and composition of phototrophic picoeukaryotes (PPE, cell size less than 3 μm) were studied in Onega Bay of the White Sea in June 2015. The highest PPE abundance and biomass were registered in the 0–5-m water layer. In the bay, in the 0–5-m water layer, the average abundance and biomass varied from 0 to 36.8 × 10⁴ cell/L and from 0 to 117 μg С/m³, respectively. The Illumina sequencing of V4 region of 18S rRNA gene revealed eight classes of PPE. Mamiellophyceae dominated both by number of reads and by operational taxonomic units. The green algae Bathycoccus prasinos, Ostreococcus tauri, and Micromonas pusila, as well as diatoms Skeletonema marinoi and Minidiscus trioculatus, were identified to the species level.     

Unusual abundance of macrobenthos and biological invasions in the Chukchi Sea

The data from the expedition of the program RUSALCA conducted in 2004 showed unexpectedly high quantitative indices of macrobenthos in the southeastern Chukchi Sea. Extensive areas of the bottom northwest of the Bering Strait were dominated by the bivalve Macoma calcarea. The greatest biomass of benthos in Macoma-dominated areas was 4232 g/m² with an average of 1382 g/m² for the investigated region. Such a high biomass of soft-bottom communities, which is extremely uncommon even in the temperature regions of the oceans, is reported for the Arctic for the first time. The long-term existence (more than 70 years) of highly productive benthic communities dominated by Macoma calcarea in one and the same area of the Chukchi Sea can most likely be attributed to gyres, which constantly arise in the region northwest of the Bering Strait. These cyclonic gyres carry nutrient-rich bottom water to the surface and hinder larval transport away from mother populations. They also keep and concentrate major food sources of benthos (live and dead phyto-and zooplankton and fecal pellets) over the benthic community locations. Most likely, a significant proportion of the primary production in the southeastern Chukchi Sea is used by benthos within the investigated Macoma community. Findings of three relatively large warm-water Pacific species near Point Hope in the Chukchi Sea are probably indicative of the progressive climate warming during the last century.     

Biomass and element pools of understory vegetation in the catchments of Čertovo Lake and Plešné Lake in the Bohemian Forest

This paper presents data on species composition, biomass, and element pools (C, N, P, Ca, Mg, Na, K, Al, Fe, Mn) of the understory vegetation of spruce forests in the catchments of lakes ?ertovo jezero (CT) and Ple?né jezero (PL) in the Bohemian Forest (?umava, Czech Republic). Calamagrostis villosa was the most abundant species in the CT catchment, while Vaccinium myrtillus was the most abundant species in the PL catchment. The catchments weighted mean (CWM) of above-ground biomass of the understory vegetation was 288 and 723 g m^?2 in the CT and PL catchments, respectively. The significant difference in the biomass between the catchments was caused by the much higher abundance of V. myrtillus in the PL catchment. The CWM of below-ground biomass of the fine roots was 491 and 483 g m^?2 in the CT and PL catchments, respectively. The respective CWM element pools of biomass in the CT and PL catchments were: C (33 and 51 mol m^?2), N (0.8 and 1.0 mol m^?2), P (24 and 34 mmol m^?2), Ca (53 and 113 mmol m^?2), Mg (24 and 41mmol m^?2), Na (3.7 and 6.5 mmol m^?2), K (83 and 109 mmol m^?2), Al (50 and 42 mmol m^?2), Fe (13.3 and 7.3 mmol m^?2), and Mn (4.2 and 8.8 mmol m^?2).     

Peculiarities of the Structure of and Trends in the Macrobenthos Community of the Ermolinskaya Bay Lagoon Ecosystem,Kandalaksha Bay,White Sea

The species composition and spatial and trophic structures of the macrobenthos communities of the Ermolinskaya Bay were studied, and the main changes that had occurred since previous explorations (the 1960s) were analyzed. The most significant changes in the spatial structure of the macrobenthos community (species diversity, population density and biomass, and similarities of the species’ distribution) were observed with regard to the sea level zone: the most pronounced at the upper littoral, followed by the middle littoral, lower littoral, and sublittoral. The longitudinal gradient of the community structure (from the innermost area seaward) was pronounced less strongly. Altogether, four macrobenthos communities can be identified in Ermolinskaya Bay; they differ in species composition, diversity, population density and biomass, and trophic structure: (1) community of the upper littoral with the dominance of collecting deposit feeders, Hydrobia ulvae, and scrapers, Littorina saxatilis; (2) community of the middle littoral with the prevalence of deposit feeders, Hydrobia ulvae and Macoma balthica, seston feeders, Mya arenaria, and, to a lesser extent, Mytilus edulis; (3) community of the lower littoral with the domination of the filtering organisms, Mytilus edulis, to a lesser extent collecting deposit feeders, Hydrobia ulvae and Macoma balthica, and scrapers, Littorina littorea; and (4) community of the sublittoral, where the leading positions belong to the group of collecting deposit feeders, Macoma balthica, to a lesser extent also Hydrobia ulvae (in the innermost area) and Capitella capitata, Arenicola marina (in the marine part of the bay). The gradual siltation of the bay and the reduction of its connection to the sea have led to the development of a littoral complex of species in the sublittoral, whereas the species typical at the sublittoral in the 1960s are now mainly found at the outlet of the bay.     

Nutrient release rates from the sediments of Saginaw Bay,Lake Huron

Direct measurements of net production rates and pore water profiles of solutes in the fine-grained sediments of Saginaw Bay, imply corresponding steady-state fluxes to the overlying water of 1.1–1.3 (I), 450–1010 (NH₄ ⁺), 1250–2650 (Si(OH)₄), 3000–3400 (Ca²⁺), 440–1330 (Mg²⁺), 1.5–728 (Fe²⁺), and 179–281 (Mn²⁺) moles/m²/day and 11.0–11.8 (alkalinity) meq/m²/day at 17.5 °C. Silica production rates in sediments apparently follow first order kinetics with a rate coefficient of 0.09/day and a steady-state silica concentration of 1.2 mM at 23.5°C. The remaining solutes follow kinetics approximately independent of solute concentration over the range of concentrations observed. Measured solute production rates are consistent with observed solute profiles only if lateral diffusion gradients are maintained in the sediments by the burrowing and irrigation activity of benthic organisms such asChironomous, the dominant burrower in Saginaw Bay. Assuming that solute fluxes from Saginaw Bay are representative of all of the post-glacial sediments of Lake Huron, the iodine flux from sediments is comparable to the total fluvial input of iodine. The extrapolated silica fluxes from Lake Huron sediments balance the estimated biogenic silica flux to the sediments.     

The primary production of Amursky Bay (Sea of Japan) in the summer of 2008

In July 2015, the assimilation number (An) of phytoplankton in Amursky Bay was measured using optical dissolved oxygen sensors (Rinko). The primary production (PP) in the photic layer of Amursky Bay was calculated based on the measured An and chlorophyll vertical profiles obtained during a hydrochemical survey on August 23?28, 2008. The total production in the bay at that period was 840 tC/day. During a phytoplankton bloom, the excess production of biomass leading to the hypoxia of the bottom water was estimated to be approximately (1.0?2.0) × 10³ tC/day.     

The Structure of a Macroinvertebrate Community in a Northern German Lake Outlet (Lake Belau,Schleswig-Holstein) with Special Emphasis on Abundance,Biomass and Secondary Production

The structure of macroinvertebrate communities was studied at I I sampling sites of the outlet of Lake Belau in the lowlands of northern Germany. To describe the structures of macrobenthic animal communities three different units were examined: abundance, biomass, and secondary production. 112 taxa were collected from the entire stream. The numbers of species ranged from 31 (fine sand) to 70 (submerged macrophytes). For the stream, average macroinvertebrate density was 18.400 ind. M⁻¹. Density was highest at the macrophytes amounting to 35,630 individuals per m², and lowest in the pure sand with only 3,900 ind. M⁻². Average biomass (dry mass) was 194 g DM m⁻² varying from 9.8 (peat) to 381 g DM m⁻² (gravel with mollusk shells near the upstream lake). For the stream, average annual production was 129 g DM m⁻² varying from 15 (peat) to 286 g DM m⁻² (macrophytes). The highest values for each unit were found in stream sections with gravel and submerged macrophytes. Lower values occured in sections that contained peat and sand. Usually, a single structure of the macroinvertebrate community was dominated by less than ten taxa, which varied at each sampling site depending on the units observed.     

Food supply in intertidal area for shorebirds during stopover at Chongming Dongtan, China

The wetland in Chongming Dongtan, China is an important stopover site for migratory shorebirds along the East Asian-Australasian Flyway. The high-abundance macrobenthos in Chongming Dongtan allow migratory birds to refuel during the stopover. This study analyzed the distribution and density of macrobenthos in the intertidal zone. Results showed that the macrobenthos mainly consisted of gastropods, bivalves, polychaetes, crustaceans and insect larvae. The density of gastropods [(2805 ± 360) ind./m²] was the highest, accounting for up to 80% of the total macrobenthos density. Meanwhile, bivalves [(51.4 ± 7.8) g/m²] and gastropods [(38.7 ± 5.1) g/m²] together accounted for more than 90% of the total biomass. On the other hand, there were significant differences in the distribution of macrobenthos among different intertidal zones. Gastropods were mainly confined to the Scirpus zones, and bivalves to the outer Scirpus zone and the muddy and sandy flats. In terms of the spatial distribution of density, the gastropod density was higher in the north but lower in the south. However, no significant difference was found in the density and biomass of macrobenthos groups between spring and autumn, except that the density of bivalves in autumn was significantly higher than that in spring (P < 0.001).