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.     

Macrophytes as dispersal vectors of zooplankton resting stages in a subtropical riverine floodplain

The resting stages of freshwater zooplankton constitute a special mechanism for passive dispersal, often displaying a variety of adaptations so as to ease transport. In floodplain systems, macrophytes are one of the most representative biotic groups showing interactions with the zooplankton community. The annual fluctuations in the hydrometric level of the Paraná River favour the displacement of this aquatic vegetation in floodplain environments. This paper hypothesizes that the roots and submerged portions of different macrophytes contain zooplankton resting stages which are able to hatch when environmental conditions are favourable. In turn, this contributes to the dispersal of zooplankton by plants when they are displaced by the flood pulse. Six macrophyte species were sampled (Eichhornia crassipes, Azolla filiculoides, Limnobium spongia, Pistia stratiotes, Eichhornia azurea and Nymphoides indica) from lakes within the Paraná River floodplain. Roots and submerged portions of vegetation were stored (90 days) at 4 °C then incubated at 25 °C for 90 days. Hatchling emergence was recorded at 2-day intervals during this period. In total, 70 zooplankton taxa were recorded in all macrophyte samples; rotifers were the most representative group (69%) followed by cladocerans (28%) and copepods (3%). The roots and submerged parts of aquatic vegetation house viable zooplankton resting stages. This phenomenon allows the dispersal of resting stages and therefore colonization of new habitats during the displacement of macrophyte species.     

Seasonal changes of macrozooplankton and Benthic Boundary Layer macrofauna from the Bay of Saint-Brieuc (western English Channel)

The macrozooplankton and Benthic Boundary Layer (BBL) macrofauna over a coarse sand and pebble community in the Bay of Saint-Brieuc (western English Channel) were sampled with a WP2 zooplankton net and with a modified MACER-GIROQ suprabenthic sledge, respectively, from February 1994 to November 1995. One hundred and sixty-four species were collected in 44 suprabenthic sledge hauls and 19 taxa in 30 zooplankton net hauls. In the water column, appendicularians and cnidarians dominated, while, in the BBL, holoplanktonic amphipods, chaetognaths, amphipods and mysids dominated the fauna; among them Apherusa spp., Sagitta setosa Muller, Anchialina agilis (Sars), Sirella clausii Sars and Eusirus longipes Boeck were the dominant species. The density and biomass of the BBL macrozooplankton were lower than those of the macrozooplankton in the water column. The density and biomass of suprabenthos remained a low throughout the year. In the water column, density and biomass of macrozooplankton showed a maximum in spring and remained low from autumn to winter; conversely, in the BBL, the density and biomass of both macrozooplankton and suprabenthos were higher from summer to autumn. The change in abundance of both BBL and pelagic taxa was seasonal. Some species were primarily sampled in the water column (appendicularians, cladocerans and cnidarians), while others were preferentially found at the BBL (suprabenthic species, holoplanktonic amphipods and cephalopods). A third group was collected throughout the water column (chaetognaths and fish larvae).      

Folk knowledge of invertebrates in Central Europe - folk taxonomy,nomenclature, medicinal and other uses,folklore, and nature conservation

Background

There is scarce information about European folk knowledge of wild invertebrate fauna. We have documented such folk knowledge in three regions, in Romania, Slovakia and Croatia. We provide a list of folk taxa, and discuss folk biological classification and nomenclature, salient features, uses, related proverbs and sayings, and conservation.

Methods

We collected data among Hungarian-speaking people practising small-scale, traditional agriculture. We studied “all” invertebrate species (species groups) potentially occurring in the vicinity of the settlements. We used photos, held semi-structured interviews, and conducted picture sorting.

Results

We documented 208 invertebrate folk taxa. Many species were known which have, to our knowledge, no economic significance. 36 % of the species were known to at least half of the informants. Knowledge reliability was high, although informants were sometimes prone to exaggeration. 93 % of folk taxa had their own individual names, and 90 % of the taxa were embedded in the folk taxonomy.Twenty four species were of direct use to humans (4 medicinal, 5 consumed, 11 as bait, 2 as playthings). Completely new was the discovery that the honey stomachs of black-coloured carpenter bees (Xylocopa violacea, X. valga) were consumed. 30 taxa were associated with a proverb or used for weather forecasting, or predicting harvests. Conscious ideas about conserving invertebrates only occurred with a few taxa, but informants would generally refrain from harming firebugs (Pyrrhocoris apterus), field crickets (Gryllus campestris) and most butterflies. We did not find any mythical creatures among invertebrate folk taxa. Almost every invertebrate species was regarded as basically harmful. Where possible, they were destroyed or at least regarded as worth eradicating. However, we could find no evidence to suggest any invertebrate species had suffered population loss as a result of conscious destruction. Sometimes knowledge pertaining to the taxa could have more general relevance, and be regarded as folk wisdom concerning the functioning of nature as a whole.

Conclusions

The high number of known invertebrate folk taxa suggests that it would be worth conducting further investigations in other areas of Europe.

     

Microcystins derived from lysing Microcystis cells do not cause negative effects on crustacean zooplankton in Lake Taihu, China

Microcystins (MCs) have a toxic effect on crustacean zooplankton in the laboratory, but there is little or no unequivocal evidence in the literature of their lethal effects on crustacean zooplankton in the field. We used the natural microcystins extracted from Microcystis spp. to test if they could cause any negative effects on crustacean zooplankton. We conducted three experiments in enclosures with water from Lake Taihu, China, and microcystins derived by extraction from Microcystis spp. collected from the lake when the species was in bloom conditions. Initial concentrations of extracellular microcystins (EMCs = MC-RR + MC-LR + MC-YR) ranged from 9.7 to 44.9 μg/L in treatments with microcystin addition. Microcystin concentrations sharply decreased on second day in all the three experiments. EMCs at the end of the experiments varied from only 2.7 to 14.2 % of the levels at the start of the experiments. The dominant species of crustacean zooplankton in the lake were Bosmina longirotris, Ceriodaphnia cornuta, Mesocyclops spp., Limnoithona sinensis, Sinocalanus dorrii and Schmackeria inopinus. ANOVA analysis showed that the density and biomass of cladoceran and copepod did not significantly differ between treatments with microcystin addition and controls. Our results indicate that microcystins derived from lysing Microcystis do not cause any negative effects on crustacean zooplankton.     

Behavioural responses of zooplankton to the presence of predatory jellyfish

The major objective of this study was to investigate the behavioural responses of several zooplankton species to the presence of the scyphozoan jellyfish, Catostylus mosaicus. Specific aims included: identifying taxa that were not captured by C. mosaicus; investigating whether some of these taxa were able to detect and avoid water that had been exposed to C. mosaicus; and determining if positive phototaxis of crab megalopae was suppressed in the presence of C. mosaicus. Zooplankton not caught by C. mosaicus were identified by comparing the zooplankton present in the water column to those on the oral arms of the jellyfish. C. mosaicus mainly caught mollusc veligers and copepods, but did not catch crab megalopae, small prawns or post-flexion fish larvae. The hypothesis that these taxa were able to avoid swimming in water exposed to C. mosaicus was tested using water-choice experiments in a flume tank. A significant proportion (18-25%) of larval barramundi (Lates calcarifer) avoided swimming in the plume of water that had been exposed to C. mosaicus but mud crab (Scylla serrata) megalopae and juvenile prawns showed no response. The effect of C. mosaicus on the positive phototaxis of S. serrata megalopae was tested using 1 m tall glass towers. Megalopae were exposed to one of four treatments: filtered seawater (a control), an oral arm of C. mosaicus, an oral arm that had been sealed in plastic, and mucus from C. mosaicus. Megalopae migrated higher into the water column in the control than in treatments containing cues from the jellyfish. These findings suggest that blooms of jellyfish may induce behavioural changes in some zooplankton.     

Bacteria of the gamma-subclass Proteobacteria associated with zooplankton in Chesapeake Bay

The seasonal abundance of gamma-subclass Proteobacteria, Vibrio-Photobacterium, Vibrio cholerae-Vibrio mimicus, Vibrio cincinnatiensis, and Vibrio vulnificus in the Choptank River of Chesapeake Bay associated with zooplankton was monitored from April to December 1996. Large (>202- microm) and small (64- to 202- microm) size classes of zooplankton were collected, and the bacteria associated with each of the zooplankton size classes were enumerated by fluorescent oligonucleotide direct count. Large populations of bacteria were found to be associated with both the large and small size classes of zooplankton. Also, the species of bacteria associated with the zooplankton showed seasonal abundance, with the largest numbers occurring in the early spring and again in the summer, when zooplankton total numbers were correspondingly large. Approximately 0.01 to 40.0% of the total water column bacteria were associated with zooplankton, with the percentage of the total water column bacteria population associated with zooplankton varying by season. A taxonomically diverse group of bacteria was associated with zooplankton, and a larger proportion was found in and on zooplankton during the cooler months of the year, with selected taxa comprising a larger percent of the Bacteria in the summer. V. cholerae-V. mimicus and V. vulnificus comprised the bulk of the large and small zooplankton-associated Vibrio-Photobacterium species. In contrast, V. cincinnatiensis accounted for less than 0.1 to 3%. It is concluded that water column and zooplankton bacterial populations vary independently with respect to species composition since no correlation was observed between taxa occurring with highest frequency in the water column and those in association with zooplankton.     

A list of oribatid mites (Acari,Oribatida) of Vietnam

A species list of identified oribatid mite taxa (Acari, Oribatida) in the fauna of Vietnam is provided. During 1967–2015, a total of 535 species/subspecies from 222 genera and 81 families was registered. Of these, 194 species/subspecies were described as new for science from Vietnam.     

Bioturbation as Driver of Zooplankton Recruitment,Biodiversity and Community Composition in Aquatic Ecosystems

In an experimental study we assessed if benthic bioturbating invertebrates affect the recruitment (hatching) of zooplankton from the sediment, and if this effect persists as differences in the zooplankton community in the water column, that is, if bioturbation quantitatively stimulates benthic–pelagic coupling. We investigated the effects of four different benthic invertebrates (Asellus aquaticus, Chironomus plumosus, Tubifex tubifex in the presence or absence of the predator Sialis lutaria). In total, 45 zooplankton taxa hatched from the sediment and the hatching success of some of these was dependent on the species identity of the bioturbating invertebrate. The predator Sialis reduced the abundance of all three invertebrate species, but tended to positively influence the zooplankton recruitment rates, possibly through increasing the activity of the bioturbating invertebrates. The most striking effect of bioturbation on the hatching and pelagic zooplankton community properties was that, on average, 11% more species hatched in the Asellus treatment than in any other treatment. This was also mirrored in the zooplankton water column community where, on average, 7% more species established a viable population in treatments with Asellus as bioturbator. In a complementary field survey, Asellus was more common in littoral than in profundal sediments. Because Asellus strongly affected recruitment of zooplankton in our experiment, we argue that bioturbation may partly explain why recruitment of resting stages of both phyto- and zooplankton is generally higher in littoral than in profundal areas.     

The Afromontane Cladocera (Crustacea: Branchiopoda) of the Rwenzori (Uganda–D. R. Congo): taxonomy,ecology and biogeography

The timely characterization of high-altitude freshwater habitats allows an assessment of the diversity of its biota and provides the basis for monitoring community change. In this study, we investigate the Cladocera fauna of 29 water bodies (pools, freshwater lakes, and surrounding swamps sampled at various occasions between 2005 and 2009) in the Rwenzori Mountains (Uganda, D. R. Congo), which are part of the East African Sky Island Complex. All sites except one are located above 3700 m altitude. We include notes on the morphology, taxonomy, distribution, and ecology of each recorded taxon and describe a new species of the Alona rustica-group (Alona sphagnophila n.sp.; Chydoridae). We found 11 species of which seven are restricted to Lake Mahoma, the lowest lake in our study area (2990 m) (Alona affinis barbata, A. intermedia, Alonella exisa, Alonella nana, Daphnia cf. obtusa, Pleuroxus aduncus) and/or Lake Bujuku (Daphnia cf. curvirostris, P. aduncus) (3900 m). Two taxa (Ilyocryptus cf. gouldeni, A. sphagnophila n.sp.) are restricted to Carex/Sphagnum bogs surrounding lakes in the afroalpine zone. Pigmented populations of Chydorus cf. sphaericus occur in all the sites. It is the only cladoceran species surviving the extreme alpine and nival conditions in the Rwenzori. The species is joined by A. guttata at locations at lower altitudes (ca. 3000–4000 m), present in about half of the sites. The Rwenzori Cladocera fauna is characterized by a strong extratropical temperate component and a low level of speciation/endemism. Harboring an impoverished boreal cladoceran community, Lake Mahoma is given closer attention. At 2990 m, the lake is a cold-temperate aquatic island in the tropics and may function as a stepping stone for Palaearctic taxa. We introduce a new term for high-altitude, cold-water habitats in the tropics, which act as climatic islands for extratropical freshwater faunas, Löffler Islands, in honor of Dr Heinz Löffler. In comparison to surveys in 1961, we list five new records in Lake Mahoma, which could indicate cladoceran community changes over the past few decades at ca. 3000 m in the Rwenzori. Since the species distributions correlate to temperature and catchment properties of the lakes, the Rwenzori cladoceran fauna can be expected as sensitive indicators for local changes.     

Occurrence of Enterococci on Plants in a Wild Environment

Enterococci were obtained from 14% of nearly 2,200 flowers, 3.4% of non-floral structures of angiosperms, and from 8.3% of samples of soil, water, and lesser plants of the Great Smoky Mountains National Park, an area little influenced by the presence of man. The enterococci were recovered from one or more flowers or flower clusters of 1,515 samples in 47 taxa, but not from flowers of 67 taxa with 654 samples. The per cent of recovery was influenced adversely by dense forest cover and by increase in elevation, as compared with recovery from flowers in sunny locations in the lower elevations. The per cent recovery increased directly with rising seasonal temperature, with the maximal per cent of recovery occurring in September. In no instance did all samples of a species of flower or plant yield enterococci on culture, and with only three genera, Cacalia, Delphinium, and Mitchella, were the bacteria obtained from more than 50% of the samples. Approximately 11% of the cultures isolated were identified as Streptococcus faecalis, 64% as the soft curd producing, caseolytic variant of S. faecalis, 4% as S. faecalis var. zymogenes, and 20% as S. faecium. The per cent distribution of these species on plants was reasonably similar to the distribution within wild animals in the same environment. It was concluded that the enterococci occurring on plants arise commonly from the wild animals, and that they do not represent plant-specific species or variants of the enterococci.     

Structure and dynamics of zooplankton communities in the littoral zone of some North Carolina lakes

Species composition and seasonal, dynamics of zooplankton in the littoral zone were studied in three piedmont North Carolina lakes for one year. Nygaard's compound index indicated oligotrophic conditions in Belews Lake and eutrophic conditions in Salem Lake and Lake 150. A total of 32 species of zooplankton were found in the samples. Significantly fewer species of truely littoral zooplankton were present in the oligotrophic lake regardless of season (P < 0.05). Eutrophication appears to favor increased diversity in zooplankton of the littoral zone. Habitat heterogeneity, provided by a well developed littoral zone containing aquatic macrophytes, may be the major factor contributing to the maintenance of more taxa of zooplankton in eutrophic systems.Distinct taxa of Cladocera and Copepoda are present in the littoral zone, exhibiting seasonal dynamics that are largely different from the limnetic fauna. Such dynamics may result from predation by characteristically limnetic species of cyclopoid copepods which seek prey in the littoral zone. The numerical and seasonal abundance of predators and prey are inversely related and the true littoral taxa, represented in the present study by the genera Alona, Chydorus, Pleuroxus, Sida, Simocephalus, and Eucyclops, contained no predaceous species. The seasonal dynamics of these genera are very similar even in widely separated geographical regions, indicating that the factor(s) responsible operate independently of climatic and chemical variables. Intrazooplankton predation appears to be a more plausable explanation than segregation along depth which, although consistent with data from studies of limnetic waters, cannot be related to populations of zooplankton in shallow littoral areas.     

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。     

Genotypic and Phenotypic Diversity of Cyanobacteria in Biological Soil Crusts of the Succulent Karoo and Nama Karoo of Southern Africa

Biological soil crusts (BSCs) are communities of cryptogamic organisms, occurring in arid and semiarid regions all over the world. Based on both morphological identification and genetic analyses, we established a first cyanobacterial inventory using the biphasic approach for BSCs within two major biomes of southern Africa. The samples were collected at two different sites in the Succulent Karoo and one in the Nama Karoo. After cultivation and morphological identification, the 16S rRNA gene was sequenced from the cyanobacterial cultures. From the soil samples, the DNA was extracted, and the 16S rRNA gene sequenced. All the sequences of the clone libraries from soil and cultures were compared with those of the public databases. Forty-five different species were morphologically identified in the samples of the Succulent Karoo (observatories of Soebatsfontein and Goedehoop). Based on the genetic analyses, 60 operational taxonomic units (OTUs) were identified for the Succulent Karoo and 43 for the Nama Karoo (based on 95 % sequence similarity). The cloned sequences corresponded well with the morphologically described taxa in cultures and sequences in the public databases. Besides known species of typical crust-forming cyanobacterial genera (Microcoleus, Phormidium, Tolypothrix and Scytonema), we found sequences of so far undescribed species of the genera Leptolyngbya, Pseudanabaena, Phormidium, Oscillatoria, Schizothrix and Microcoleus. Most OTUs were restricted to distinct sites. Grazed soils showed lower taxa numbers than undisturbed soils, implying the presence of early successional crust types and reduced soil surface protection. Our combined approach of morphological identification and genetic analyses allowed both a taxa inventory and the analysis of species occurring under specific habitat conditions.     

Diversity of Rotifera (Monogononta) in wetlands of Río Pilcomayo National Park, Ramsar Site (Formosa, Argentina)

The rotifers at this Ramsar site were inventoried for the first time. A total of 114 taxa, belonging 30 genera were found in samples collected from four aquatic habitats in the Río Paraguay basin, in northern Argentina. The rotifer fauna is characterized by a large proportion of cosmopolitan and tropicopolitan species and few species endemic to the Neotropical Region (5%). In the list, 22% of the taxa are new to the Argentine fauna. Colurella sinistra Carlin is a new record to the Neotropical fauna. Ecological and distributional notes on selected species are included.     

A comparison of zooplankton communities in saline lakewater with variable anion composition

Although salinity and aquatic biodiversity are inversely related in lake water, the relationship between types of salts and zooplankton communities is poorly understood. In this study, zooplankton species were related to environmental variables from 12 lakes: three saline lakes with water where the dominant anions were SO₄ and CO₃, four saline lakes with Cl-dominated water, and five dilute, subsaline (0.5–3 gl^?1 total dissolved solids) lakes of variable anion composition. Although this study comprised only 12 lakes, distinct differences in zooplankton communities were observed among the two groups of chemically defined saline lakes. Canonical correspondence analysis identified total alkalinity, sulphate, chloride, calcium, sodium, potassium, and total phosphorus as all contributing to the first two ordination axes (λ₁ = 0.97 and λ₂ = 0.62, P<0.05). The rotifer Brachionus plicatilis and the harpactacoid copepod Cletocamptus sp. prevailed lakes with Cl-dominated water. In contrast, the calanoid copepods Leptodiaptomus sicilis and Diaptomus nevadensis were dominant in the SO₄/CO₃-dominated lake water with elevated potassium (79–128 mg l^?1) and total phosphorus concentrations (1322-2915 μg l^?1). The contrasting zooplankton species distribution among these two saline lake types is likely explained by variable selective pressure on zooplankton and their predators from differing physiological tolerances to salt stress and specific ions. While inland saline lakes with Cl as the dominant anion are relatively rare in Canada and SO₄/CO₃ are the common features, our study provided an opportunity to compare zooplankton communities across the two groups of lakes.     

Pelagic fish and zooplankton species assemblages in relation to water mass characteristics in the northern Bering and southeast Chukchi seas

This research explores the distributions and community composition of pelagic species in the sub-Arctic and Arctic waters of the northern Bering and central and southern Chukchi seas during September 2007 by linking pelagic zooplankton and fish assemblages to water masses. Juvenile saffron cod (Eleginus gracilis), polar cod (Boreogadus saida), and shorthorn sculpin (Myoxocephalus scorpius) were most abundant in warm, low salinity Alaska Coastal Water (ACW) of the central Chukchi Sea, characterized by low chlorophyll, low nutrients, and small zooplankton taxa. Adult Pacific herring (Clupea pallasii) were more abundant in the less stratified Bering Strait waters and in the colder, saltier Bering Shelf Water of the northern Bering and southern Chukchi seas, characterized by high chlorophyll, high nutrients, and larger zooplankton taxa. Juvenile pink (Oncorhynchus gorbuscha) and chum (O. keta) salmon were most abundant in the less stratified ACW in the central Chukchi Sea and Bering Strait. Abundances of large zooplankton were dominated by copepods (Eucalanus bungii, Calanus glacialis/marshallae, Metridia pacifica) followed by euphausiids (juvenile Thysanoessa raschii and unidentified taxa), whereas small zooplankton were dominated by bivalve larvae and copepods (Centropages abdominalis, Oithona similis, Pseudocalanus sp.). Pelagic community composition was related to environmental factors, with highest correlations between bottom salinity and large zooplankton taxa, and latitude and fish species. These data were collected in a year with strong northward retreat of summer sea ice and therefore provide a baseline for assessing the effects of future climate warming on pelagic ecosystems in sub-Arctic and Arctic regions.     

三沙湾浮游动物生态类群演替特征

根据2010年6月-2011年5月三沙湾海域5个航次海洋综合调查资料,对三沙湾浮游动物种群特征进行分析,并与我国不同纬度海湾生态类群结构进行比较.探讨三沙湾海域浮游动物生态类群季节变化特征及其受水团季节变化的影响.研究结果表明:4月和5月三沙湾海域主要受到浙闽沿岸流影响,生物多样性H'指数分别为2.03和2.02;种类数分别仅为17种和19种,明显低于6月、8月和10月;浮游动物生态类群以暖温带近海种为主;优势种种类数少,单一优势种优势性明显,4月中华哲水蚤丰度占浮游动物总丰度的65.03％;群落结构特征与同期我国长江口浮游动物区系特征相似.6月三沙湾海域受到浙闽沿岸流和台湾暖流共同影响,同时因闽北雨季导致大量大陆径流汇入,使得该月浮游动物种群结构复杂,生物多样性指数和种类数全年最高,为3.12和45种,与5月相比,种类更替明显,物种更替率为69.39％;亚热带近海种丰度百分比最高(73.03％),亚热带外海种种类数百分比次之(48.89％),是海域浮游动物生态类群由以暖温带近海种为主向以亚热带外海种为主的过渡时期.8月和10月浙闽沿岸流消失,三沙湾海域受台湾暖流控制,海水温度和盐度升高,生物多样性指数和种类数均略低于6月;生态类群结构以亚热带外海种为主;优势种特征表现为种类数多而各个优势种丰度较低;浮游动物群落结构特征与南海北部海域浮游动物组成极为相似.     

Diel migration patterns of demersal reef zooplankton

Demersal zooplankton reside in or near the reef substrata and usually migrate into the water column at night. There is no single pulse of migratory activity. The zooplankton rise at variable rates throughout the night, with a peak activity usually during the second hour after sunset. This temporal pattern is a reflection of the behavior of the dominant (80–90% of night samples) cyclopoid, Oithona colcarva Bowman.Not all zooplankton taxa exhibit the same diel migratory patterns. Harpacticoids, another Oithona sp., copepod nauplii, barnacle nauplii, and appendicularians are most abundant during the day. Isopods show a peak of activity also during the second hour after sunset while polychaetes are most abundant during the first hour. The behavior of the other groups studied (the cyclopoid Corycaeus sp., other cyclopoids, ostracods, amphipods, tanaids, decapods, mysids, and chaetognaths) was less easily defined.The migration of many species in a pulse during the period of least planktivore activity and migration during the day of small species and juvenile members of larger species suggests that visual predators have an important influence on the migratory behavior of reef zooplankton.     

Animal associations with the dominant species of shallow water macrophytes along the coastline of the Vestfold Hills,Antarctica

Benthic grab samples, taken through core holes in sea-ice 1983, returned eight species of marine macrophytes which had associated fauna on at least one sample. A total of 24 animal taxa were found on these eight macrophytes. Phyllophora antarctica had a significantly greater biomass of attached fauna per unit of macrophyte biomass than any of the other seven species. It also had the greatest variety of epiphytic fauna (21 taxa). Phyllophora antarctica was the only macrophyte collected from comparatively protected Ellis Fjord, apart from filamentous algae, including Cladophora subsimplex and Geminocarpus austrogeorgiae, which were found in the most landward basin. It therefore played an important role in the ecology of the fjord. Palmaria decipiens was commonly collected at more exposed coastal sites and was dominant in Long Fjord, characterized here as intermediate in terms of water movement. Sixteen animal taxa were collected from this macrophyte with the greatest numbers being found in July and August. Only four animal taxa were collected from Iridaea cordata. The other five macrophyte species from which epiphytic animals were collected (Porphyra endiviifolium, Plocamium cartilagineum, Desmarestia menziesii, Himantothallus grandifolius and Cladophora subsimplex had animals associated with them on less than half the occasions when they were found.