南沙群岛美济礁海域夏季浮游动物群落特征

浮游动物是珊瑚礁生态系统中的重要组成部分,但国内相关研究相对较少。利用2012年7月在南沙群岛美济礁海域开展的13个站次的海洋生物调查数据,对美济礁浮游动物的群落特征进行研究,表明:(1)美济礁浮游动物种类组成丰富,共出现15个类群138种(类)浮游动物;(2)优势种组成复杂、区域变化明显,单一种的优势度不高;(3)浮游动物平均密度和湿重生物量分别为117.70个/m3、69.01 mg/m3,浮游幼虫在总密度中所占比例最大;(4)浮游动物非常丰富,多样性程度较高。平均丰富度、多样性指数和均匀度分别为4.93、3.33和0.67;(5)浮游动物可划分为2个群落,分别为潟湖-礁坪区群落和向海坡群落;(6)受珊瑚礁不同生物地貌带的空间异质性和水动力条件的影响,美济礁浮游动物群落区域差异明显。潟湖区浮游动物多样性较高,生物量最低;礁坪区浮游动物数量大,但分布不均匀,且多样性水平最低;向海坡区浮游动物种类最多、多样性非常丰富,但栖息密度最低。     

Analysis of a 24-hour cycle of zooplankton sampling in a lagoon of the Po River Delta

Short-term zooplankton samples were collected in a lagoon ofthe Po River Delta (Sacca del Canarin) over a 24-h cycle inAugust 1981. The biocoenosis was mainly represented by taxa(especially copepods) coming into the lagoon from the sea and,to a lesser extent, by autochthonous zooplankton (gastropod,cirripede and decapod larvae). Density fluctuations of sometaxa were found to be greatly influenced by hydro dynamic factors,in particular by the tidal currents. A daily balance of inputand output through one of the two mouths connecting the lagoonto the sea was calculated for different taxa; quantitative estimatesof zooplankton exchanges between lagoon and sea due to tidaltransportation were obtained.     

Environmental changes and zooplankton temporal and spatial variation in a disturbed Brazilian coastal lagoon.

The Imboassica lagoon, located in the Municipality of Macaé (RJ), is separated from the sea by a sand bar, and its surroundings are partially occupied by residential areas. This coastal lagoon has undergone environmental degradation due to sewage input and artificial sand bar openings. The temporal and spatial variation of environmental variables and zooplankton were studied monthly for four years. There were five artificial openings of the sand bar during the period of study, mostly in the rainy season. Besides osmotic changes, these events caused the drainage of the water of the lagoon into the sea, loss of total organic nitrogen, and an increase of total phosphorus. The zooplankton community of Imboassica lagoon included freshwater and marine taxa, holoplanktonic, meroplanktonic and nectobenthonic forms. Polychaeta, Bivalvia and Gastropoda larvae, and the taxa of Rotifera Hexarthra spp., Lecane bulla, Synchaeta bicornis, nauplii of Cyclopoida and Calanoida copepods were considered constant taxa. Distinct zooplankton assemblages were found during zooplankton spatial surveys in oligohaline and mesohaline conditions. The successful zooplankton populations were either favored by the disturbance of the sand bar opening, such as the veligers of the gastropod Heleobia australis, or capable of fast recovery after the closing of the sand bar, during the succession from a marine into an oligohaline environment, such as Hexarthra spp.. Such populations seemed well adapted to the stress conditions usually found in the lagoon due to osmotic changes, column mixing, nutrient input, and high fish predation pressure. Rare species in the community, such as Moina minuta, presented population increases all over the lagoon under oligohaline conditions.     

Phytoplankton Fluctuations during an Annual Cycle in the Coastal Lagoon of Cullera (Spain)

The seasonal variation and the vertical distribution of the phytoplanktonic population of the lagoon of Cullera, an elongated coastal lagoon with estuarine circulation of water, has been studied in three sampling stations: mouth, centre and source. Seasonal variation is determined by a marine-freshwater interaction. In winter, the sea influence is important, a marine water wedge of anoxic water arrives at the sampling station located at the source and marine and brackish water species dominate the phytoplankton. Also marine species of zooplankton and fish enter the system, which may then be considered as exploited by the sea. In spring the marine wedge retreats from the source but remains in the centre and mouth, salinity diminishes, vertical mixing persists and phytoplankton is dominated by Cyclotella species. From late spring to autumn the freshwater influence prevails and a sharp stratification of the water is produced in the stations at the mouth and the centre, by means of a steep halocline coincident with an oxycline. The phytoplankton in this period follows a typical succession like those described in freshwater eutrophic lakes. Vertical distribution of phytoplankton is determined by the presence of the oxycline, originated by the marine water wedge, whose depth varies seasonally but which is always present in the mouth and centre of the lagoon; only few species of algae can be found below its level.     

Colonization of the gut of the blue crab (Callinectes sapidus) by Vibrio cholerae.

Attachment of Vibrio cholerae to the mucosal surface of the intestine is considered to be an important virulence characteristic. Vibrio cholerae, an autochthonous member of brackish water and estuarine bacterial communities, also attaches to crustacea, a significant factor in multiplication and survival of V. cholerae in nature. The ability of V. cholerae to attach to the gut wall of the blue crab (Callinectes sapidus) was examined, and attachment was observed only in the hindgut and not the midgut of crabs, confirming a requirement for chitin in the attachment of V. cholerae to invertebrate and zooplankton surfaces. The new finding of attachment of V. cholerae to the hindgut of crabs may be correlated with the epidemiology and transmission of cholera in the aquatic environment. The crab model may also prove useful in elucidating the mechanism(s) of ion transport in crustacea.     

Colonization of the gut of the blue crab (Callinectes sapidus) by Vibrio cholerae

Attachment of Vibrio cholerae to the mucosal surface of the intestine is considered to be an important virulence characteristic. Vibrio cholerae, an autochthonous member of brackish water and estuarine bacterial communities, also attaches to crustacea, a significant factor in multiplication and survival of V. cholerae in nature. The ability of V. cholerae to attach to the gut wall of the blue crab (Callinectes sapidus) was examined, and attachment was observed only in the hindgut and not the midgut of crabs, confirming a requirement for chitin in the attachment of V. cholerae to invertebrate and zooplankton surfaces. The new finding of attachment of V. cholerae to the hindgut of crabs may be correlated with the epidemiology and transmission of cholera in the aquatic environment. The crab model may also prove useful in elucidating the mechanism(s) of ion transport in crustacea.     

Copenhagen 1996-Variation in physical, chemical and biological components in the subantarctic lakes of South Georgia

Physical, chemical and biological variables were quantified in 19 subantarctic lakes (South Georgia) as a prelude to comparing these pristine systems with temperate lakes and to improve the knowledge of spatial and temporal variation in water chemistry and abundances of organisms. Lakes close to the sea had higher phosphorus concentrations, contained higher abundances of most organisms, and had higher number of invertebrate species than lakes situated further from the sea. Differences were attributed to higher nutrient input from marine organisms, such as penguins, seals and petrels, and probably also to a somewhat longer ice-free period. Since the lakes of South Georgia lack fish, the pelagic invertebrate fauna is dominated by herbivorous macrozooplankton. Rotifers are rare in the open water and are restricted to the vegetation (mainly mosses) in shallow areas and to the sediment surface. Generally, the algal abundance at the sediment surface is high in subantarctic lakes, indicating that the main part of the primary production is provided by benthic algae, which is in contrast to what is normally the case in temperate waters.     

Distribution patterns of micro- and meso-zooplankton communities in sea ice regions of Lützow-Holm Bay, East Antarctica

In the Southern Ocean, zooplankton research has focused on krill and macro-zooplankton despite the high densities of micro- and meso-zooplankton. We investigated their community structure in relation to different sea ice conditions around Japan’s Syowa Station in Lützow-Holm Bay, in the summers of 2011 and 2012. Zooplankton samples were collected using vertical hauls (0–150 m), with a closing net of 100-μm mesh size. The results of cluster analysis showed that the communities in this region were separated into fast ice, pack ice, and open ocean fauna. The fast ice fauna had lower zooplankton abundance (393.8–958.9 inds. m^?3) and was dominated by cyclopoid copepods of Oncaea spp. (54.9–74.8 %) and Oithona similis (6.6–19.9 %). Deep-water calanoid copepods were also found at the fast ice stations. Pack ice and open ocean fauna had higher zooplankton abundance (943.6–2,639.8 inds. m^?3) and were characterized by a high density of foraminiferans in both years (6.6–61.9 %). Their test size distribution indicated that these organisms were possibly released from melting sea ice. The pteropod Limacina spp. was a major contributor to total abundance of zooplankton in the open ocean zone in 2012 (26.4 %). The physical and/or biological changes between 2 years may affect the abundance and distribution of the dominant zooplankton taxa such as cyclopoid copepods, foraminiferans, and pteropods. Information on the relationships between the different species associated with sea ice will help to infer the possible future impacts of climate change on the sea ice regions.     

Reproductive ecology of the blue crab, Callinectes danae Smith, 1869 in the Conceição Lagoon system, Santa Catarina Isle, Brazil

Abundance of ovigerous females, size of the first gonadal maturation and the possible migration, route of the blue crab Callinectes danae from the Concei??o Lagoon system, Santa Catarina Isle, Brazil, are described. This lagoon is connected with the coastal area through a canal. A total of 1,124 crabs was caught during a 19 month sampling period. The reproduction and recruitment of juveniles occurred all year-round, with two peaks of abundance (February and September), correlated with the presence of ovigerous females (June and January). The mean carapace width at which the crabs attained gonadal maturity for the first time was 9.4 cm in males and 8.4 cm in females. The Concei??o Lagoon is a growth, reproduction, and spawning area for the species. However, egg eclosion occurs outside the lagoon following migration of ovigerous females to the open sea. After hatching the eggs, some females return to the lagoon, but males stay there for most of their life cycle.     

Aquatic plant dynamics of Waituna Lagoon, New Zealand: trade-offs in managing opening events of a Ramsar site

Coastal lagoons are at risk internationally due to impacts associated with human-induced land use change. The resilience of aquatic macrophytes in these systems is threatened by altered hydrological regimes, elevated nutrient loading, and increased dominance of nuisance species. We describe the aquatic plant dynamics of the Waituna Lagoon Ramsar Site, a 1,350?ha lagoon frequently opened to the sea for flood mitigation which is characterised by fluctuating water levels and salinity. The shallow lagoon supports a macrophyte community dominated by Ruppia megacarpa and R. polycarpa. Repeated survey of 48 sites across the lagoon during late summer in 2009, 2010 and 2011 were applied to describe aquatic plant composition and abundance. This period coincided with three opening events (winter 2008; winter 2009; spring 2010) when the lagoon switched from a predominantly fresh-brackish system to being influenced by tidal exchange and lower water levels. The lagoon experienced a period of 43?days open to the sea in 2008?C2009, 67?days in 2009?C2010 and 181?days in 2010?C2011, during which macrophytes were subject to saline conditions in excess of 10?ppt. We observed a decline in the occurrence of Ruppia from 2009 (69?% sites) to 2011 (23?% sites). The shift in productivity was associated with the duration of the open phase and the period plants were subject to saline conditions >20?ppt and low water levels. The resilience of the system is also at risk from increased algal-dominance due to the intensification of agricultural land use occurring in the Waituna Lagoon catchment. While lagoon opening events cause extreme changes in water depth and salinity that can limit macrophyte growth, they also provide a mechanism to reduce the effects of eutrophication. Understanding these trade-offs is pivotal in management decisions regarding the likely impact of opening events on the ecological character of coastal lagoons.     

Spatial and seasonal distribution of the ichthyofauna of Lake Nokoué, Bénin,west Africa

The fish biodiversity of Lake Nokoué, a lagoon in Bénin, was monitored for one year from August 2000 to July 2001 by means of samples from the artisanal fishery collected once a month at three stations. A total of 5 933 fish weighing 95 322g (mean individual weight 16.0g) belonging to 51 species, 47 genera and 34 families were sampled. An abundance of juveniles was observed, confirming the importance of the lake as nursery grounds, rich in exploitable habitats like other tropical estuaries and lagoons. The fish fauna comprised three main components: i) an estuarine component (strict, freshwater and marine origins) which is the basis of the lagoon fauna community and which is stable in space and time; ii) a marine component containing fishes which appeared in the lagoon during the dry season where the salinity remains high (>20‰) and iii) a freshwater component with fishes coming into the lagoon from the river during the flood period. The magnitude of the spatial and seasonal fluctuations of the last two components varies depending on the area: marine (Zogbo), freshwater (Vêki) or intermediate (Ganvié). The global species richness and the relative abundances of fish vary between stations and from month to month. November, with 20 species on average, and January, with 6 species on average, are significantly different as regards species richness.     

Environmental influences on the qualitative and quantitative composition of phytoplankton and zooplankton in North African coastal lagoons

Within the framework of the international research project MELMARINA, seasonal dynamics of plankton communities in three North African coastal lagoons (Merja Zerga, Ghar El Melh, and Lake Manzala) were investigated. The sampling period extended from July 2003 to September 2004 with the aim of evaluating hydrological and other influences on the structure, composition and space-time development of these communities in each lagoon. Phytoplankton in Merja Zerga showed a quasi-permanent predominance of marine diatoms in the open sea station and in the marine inlet channel. Dinoflagellates were abundant in summer and early autumn in the marine inlet and extended into the central lagoon station. In Ghar El Melh, marine species (especially diatoms and dinoflagellates) dominated despite occasional winter inflows of freshwater. In Lake Manzala, freshwater species generally predominated and the planktonic communities were comparatively very diverse. Chlorophyceae contributed 39% of the total species recorded and diatoms and cyanophyceans were also common; the Dinophyceae, Euglenophyceae, Chrysophyceae and Cryptophyceae less so. Zooplankton communities in both Ghar El Melh and Merja Zerga were dominated by marine copepods. Rotifera, Copepoda, Ostracoda, and Cladocera were recorded in both lagoons as were meroplanktonic larvae of Polychaeta, Cirripedia, Mysidacea and Gastropoda and free living nematodes. Ghar El Melh was the more productive of these two lagoons with spring and early summer being the productive seasons. Zooplankton communities in Lake Manzala were generally dominated by rotifers and highest zooplankton abundances occurred in April (2003). Sampling stations near the marine inlets showed the highest diversity and the zooplankton communities showed considerable spatial variation within this large lagoon. The three lagoons represent very different water bodies contrasted strongly in terms of tidal effects and freshwater availability. Yet, there are some similarities in ecosystem structure. Space-time development of the plankton communities was similar especially in Merja Zerga and Ghar El Melh. Species abundances and specific diversities indicated that seasonal changes in salinity and nutrient concentrations were the main influential factors. Lake Manzala was the most productive lagoon and all the three sites supported toxic algal species. Relatively low plankton biomass in Merja Zerga and Ghar El Melh probably resulted from a combination of factors including highly episodic nutrient inputs, light suppression (by turbidity) and nutrient competition with benthic algae. Water quality variables were largely driven by the hydrological regime specific to each lagoon. Nutrient enrichment and, particularly for Lake Manzala, sea level rise threaten the sustainability of the planktonic ecosystems in all three lagoons. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Proportion of dead individuals in the zooplankton of the Curonian Lagoon of the Baltic Sea

Changes have been studied in space and time in the proportion of dead individuals in the zooplankton of the Curonian Lagoon. Dead individuals were found in the populations of all dominant invertebrate species. Their proportion was shown to increase during “hyperbloom” by a factor of 5 to 6. In the vegetation period without algal hyperbloom (2007), the dead individuals accounted on average for 1.9 ± 0.7% of the total abundance and 1.7 ± 0.8% of the total biomass of zooplankton; in the vegetation period with hyperbloom (2008), their proportion increased to 6.7 ± 3.0% and 5.9 ± 2.5%, respectively. Differences in sensitivity to bloom of Cianobacteria have been revealed in hydrobionts from different groups. Cladocera and nauplial Copepoda are the most sensitive groups; Cyclopoida is the least sensitive. The highest proportion of dead individuals was recorded in the most eutophicated and polluted part of the lagoon. It is suggested that parameters of zooplankton mortality be used for estimating the ecological state of the Curonian Lagoon.     

A Model for Aquatic Invertebrate Response to Kissimmee River Restoration

When the Kissimmee River was channelized in the 1960s and 1970s and placed under stage-fluctuation management, the dynamic interactions between the river and the flood-plain were essentially removed. Correspondingly, aquatic invertebrate life in the river and floodplain ecosystem shifted from a riverine to a more lacustrine fauna. A relinkage of the Kissimmee River with the floodplain following restoration will result in numerous changes to such ecologically important factors as streamflow, substrate composition, food quality and quantity, and water quality, all of which will influence invertebrate communities. These factors and their function in the ecosystem as the fauna shifts from predominantly lacustrine back to riverine are presented in a conceptual model. As an integral component of all aquatic ecosystems and a key link between primary producers and higher trophic levels, aquatic invertebrates are a valuable group with which to evaluate the recovery of the Kissimmee River. Utilization of a geographic information system mapping approach linking expected increased habitat heterogeneity and invertebrate richness with restoration efforts is suggested as an economical means of monitoring recovery of the Kissimmee River ecosystem.     

Patterns of distribution of macroinvertebrate families in rivers of north-western Australia

1. The northern half of Western Australia is a large, sparsely populated area with a climate that ranges from monsoonal in the Kimberley to arid in the Gascoyne and Pilbara regions. The aquatic invertebrate fauna is poorly known. 2. Fifty-one sites located on 14 river systems were sampled three times between August 1994 and October 1995. A total of 90 taxa, most identified to family level, were collected. The fauna was dominated by insects, which constituted 74% of the total number of taxa collected. 3. Major habitats at each site were sampled separately and sites with more habitats tended to have a richer fauna. All habitats showed significant differences in taxonomic richness between regions. Family richness decreased with increasing latitude, being highest in the Kimberley region and lowest in the Gascoyne. 4. Despite the differences in taxon richness between regions, community composition of the aquatic invertebrate fauna at the family level did not differ greatly. Four major groups of sites were identified by cluster analysis, based on the invertebrate families present at each site, but differences between groups were small. 5. Significant temporal variation in taxon richness was found in channel habitat but not the three other habitats sampled (riffle, macrophyte, pool-rocks). Community composition in channel habitat varied temporally among groups of sites identified by cluster analysis but the pattern was not consistent.     

Evolution saisonniere du zooplancton dans trois sites peu profonds de Thau,une lagune Nord-Mediterraneenne

A monthly zooplankton survey has been conducted from March 1982 to March 1983 at three shallow stations of Thau, a northern-mediterranean lagoon. These stations differ by their distance from the entry of sea-water in the lagoon. Parameters such as pH, temperature, dissolved oxygen, conductivity and turbidity have been measured simultaneously with the sampling in the same water layer. The zooplankton collected corresponds to species usually found in marine neritic communities. In the spring, species richness is maximum. During the summer, meroplankton forms dominant populations in the communities. Autumn is marked by a reduction of the number of species and of the abundance in both components, holoplankton and meroplankton. Few species are present in the winter holoplankton while meroplankton disappears practically from the samples. The sites under observation are subjected to unpredictable changes, in water movement as well as in the organization of the zooplankton communities. These modifications are strongly influenced by weather conditions.     

Spatial distribution patterns of the hyporheic invertebrate communities in a polluted river in Romania

The purpose of this study was to examine the sensitivity, in a field situation, of the hyporheic fauna to pollution by heavy metals and also to test the use of oxidative stress enzymes produced by this fauna as a sensitive indicator of oxidative stress generated by chemical contamination. This was done by surveying the patterns of distribution, structure, and composition of hyporheic invertebrate communities in one of the most polluted rivers in Romania. Twelve permanent sampling stations with differing water qualities were established along a 180 km transect of the Arie? River. Data on hyporheic invertebrate abundance and richness, chemistry of the surface and hyporheic water and interstitial suspended particles were analyzed via multifactorial analyses. In the downstream, more polluted stations, epigean species were less abundant and hyporheic communities, especially macrocrustaceans and oligochetes, became dominant. The higher levels of hyporheic invertebrate biodiversity in the moderately polluted stations compared to highly polluted, and the increase of the number of some hyporheos (especially macrocrustaceans) in the moderately polluted stations, suggested that the hyporheic fauna was more tolerant of heavy metal pollution than the surface water fauna of the area. However, the different richness and abundance of hyporheic fauna in sites of similar water chemistry suggested that additional factors, such as sediment structure are shaping the spatial distribution of hyporheic fauna. Strong correlations between superoxide dismutase (SOD) activity in pooled tissues extracts and some chemical parameters suggest that oxidative stress enzymes may prove to be sensitive indicators of chemical pollution in hyporheic zones.     

The influence of habitat structure and flow permanence on invertebrate communities in karst spring systems

The macroinvertebrate fauna of five karst (limestone) springbrook systems with contrasting physical habitat and discharge patterns were investigated to examine the role of flow permanence and habitat structure on macroinvertebrate community composition. Clear physical differences were identified between perennial and intermittent springs and individual sampling stations. However, flow permanence, water temperature and the input of leaf litter exerted a greater influence on the aquatic invertebrate community than habitat structure. Perennial sites were characterised by a greater abundance of macroinvertebrates and greater Ephemeroptera, Plecoptera and Trichoptera (EPT) richness than intermittent sites. The fauna of all of the springbrook systems examined were dominated by relatively common and ubiquitous taxa (e.g. Gammarus pulex) although a number of taxa displaying life cycle adaptations to ephemeral aquatic habitats (e.g. Limnephilus auricula and Stenophylax permistus) were recorded at intermittent sites.     

Plankton studies in a lacustrine environment

Summary Weekly zooplankton samples were taken during the period February, 1972 to January, 1973 at station III in a shallow and turbulent tropical reservoir (Broa Reservoir, São Carlos, São Paulo, State-Brazil). The samples were taken by plankton standard net with 68 mesh size, and collected through the horizontal hawls during 3 min. Rotifera was the most abundant group with 77.6%; Cladocera 13.6%, and Copepoda 8.7% (adult and naupliae stages). Other forms like Chaoborus larvae and some worms occurred sporadically. The seasonal fluctuation of the total zooplankton was very irregular in warm and rainy season and more stable in the dry and cold season. The composition of the zooplankton and its patterns of seasonal variation for eutrophic and oligotrophic aquatic ecosystems, in tropical regions, may differ significantly from temperate waters.     

The zooplankton and other limnological features of a humic coastal lagoon (Lagoa Comprida,Macé, R.J.) in Brazil

Comprida lagoon is a shallow lagoon separated from the sea by a sand barrier. It has a brown-coloured freshwater with a high concentration of humic compounds. Its zooplankton community and limnological features were studied from March 1992 to December 1995. The lagoon was characterized by low transparency, acid water and relative constant physical–chemical features, except during sporadic marine entrances. The zooplankton, composed of holoplanktonic and meroplanktonic forms, consisted of 60 taxa. Eleven were permanent elements of the community: e.g. Bosminopsis deitersi, nauplii and copepodites of `Diaptomus' azureus. B. deitersi correlated positively with the lowest pH values and with the highest total dissolved nitrogen. Only four taxa correlated with chlorophyll-a concentration. Pigmentation in `D.' azureus is suggested to be as an energy reserve in a system where phytoplankton is probably light-limited.