Abundance and biogeography of tintinnids (Ciliophora) and associated microzooplankton in the Southwestern Atlantic Ocean

Absolute abundances of foraminifers, polycystine and phaeodarian radiolarians, tintinnids, pteropods and early crustacean larvae and moults were assessed in a collection of 57 vertically stratified (0-100 m) net microplankton samples from 22 stations located between 34 and 58S (along 51-56°W), covered on 8-16 November 1994. Tintinnids were identified to species and measured in order to estimate their biomass from biovolume to carbon conversions. The distribution of the microzooplanktonic groups assessed was irregular and patchy, both geographically and vertically, and their abundances were characteristic of oceanic low to medium productivity environments. Tintinnid biomass was also generally low (0.05-0.40 g Cl^-1). With the exception of the tintinnids, associations between microzooplanktonic numbers and chlorophyll a were generally loose. Eighty-eight tintinnid taxa were recorded, yet only five accounted for 53% of the specimens identified. Multivariate (cluster) analysis of tintinnid specific distribution patterns clearly showed several distinct zones. From north to south, these are: Transition Zone (TZ), with three subzones, TZ north (34°S-38°S), TZ central (39°44S-44°S) and TZ south (46°S); Subantarctic Zone (SZ; 48-55°S); Polar Front Zone (55°30S); Antarctic Zone (AZ; 58-59°36S). Each of these was characterized by distinct tintinnid assemblages, abundance and biomass. With few exceptions, tintinnid cells were fairly evenly distributed throughout the upper 50 m. Taxonomic composition usually changed little with depth. Mean population depths were calculated for a subset of 35 tintinnids; 29 of these dwell preferably above 40 m. The spatial distribution of tintinnid species richness showed a more or less gradual decrease from north to south. Specific diversity and equitability generally increased with depth, and were higher in antarctic waters than the southern transitional and subantarctic ones; this trend is tentatively attributed to higher water column vertical stability south of the Polar Front.      

Estuarine diversity of tintinnids (planktonic ciliates)

In Chesapeake Bay, a large eutrophic and partially stratifiedestuary, we investigated diversity among tintinnids (Ciliophora,suborder Tintinninia) in September 1999. In contrast with thetypical estuarine pattern, tintinnid diversity was high andincreased with decreasing salinity from the mouth of the bayto the mid-bay region. Peak species numbers and diversity values[20–25 species, H' (ln) = 2.4–2.5] were found instations in the mesohaline (14–17     

Size-fractionated chlorophyll a biomass and picophytoplankton cell density along a longitudinal axis of a temperate estuary (Southampton Water)

Size-fractionated chlorophyll a biomass and picophytoplanktoncell number distributions were investigated along a longitudinalaxis of Southampton Water estuary during autumn. Chlorophylla concentration in the >5µm and the 1–5 µmsize fractions was highest midway down the estuary, and decreasedboth in the landward and seaward directions. In contrast, chlorophylla biomass in the 0.2–1 µm size fraction showed nodecline towards the seaward end of the estuary. In agreementwith this observation, phycoerythrin-containing picocyanobacteriacell concentration showed a positive exponential-like relationshipwith salinity and eukaryotic picophytoplankton were also highestat high salinities. Expressed as a percentage of total, chlorophylla standing stock in both the 1–5 µ.m (4.4–28.7%)and the 0.2–1 µm size fractions (1.7–8.6%)was inversely correlated with total chlorophyll a concentration.Both these two fractions made a greater input to the total phaeopigmentconcentration than to the total pool of active chlorophyll a.     

Genetic analysis reveals the diversity of larval Gobiidae in a temperate estuary

Using molecular tools to examine Gobiidae, the second most abundant taxon in ichthyoplankton samples in the Gulf of Riga (Baltic Sea), the sand goby Pomatoschistus minutus was the most abundant taxon (82% of all individuals analysed), the common goby Pomatoschistus microps constituted 12% and the black goby Gobius niger 6%. The spatiotemporal distribution of P. microps and G. niger indicated a preference for habitats closer to the river inlet and their abundances increased slightly towards the end of the sampling period in summer. The species composition was interpreted in the context of the prevailing habitat conditions, characterized by extremely low water transparency, low salinity, limited spread of vegetated area and dominance of sandy–muddy substrata.     

莱州湾大型砂壳纤毛虫群落季节变化

为揭示莱州湾砂壳纤毛虫群落季节变化规律, 在莱州湾设置8个站位, 于2011年5-11月及2012年3-4月进行了9个航次的调查, 用浅海III型浮游生物网由底至表垂直拖网采集砂壳纤毛虫。结果表明, 莱州湾3-11月砂壳纤毛虫物种丰富度的变化范围为5-19, 周年变化呈现一峰两谷的趋势。丰度的范围为0-318 ind./L, 丰度较大(> 50 ind./L)的种类有运动类铃虫(Codonellopsis mobilis)和清兰拟铃虫(Tintinnopsis chinglanensis)。各月平均丰度随时间的变化趋势为双峰型, 最大值出现在7月(63 ind./L), 次峰值出现在5月(48 ind./L), 最小值出现在3月(2 ind./L)。黏着壳种类在3-11月均有出现, 透明壳种类仅在温度较高(> 15°C)的6-9月出现。各月的优势种数目为1种(5月)到8种(8月), 其中运动类铃虫在所有月中都是优势种, 对砂壳纤毛虫丰度周年的变化规律产生较大影响。使用各月所有种类的平均丰度对各月砂壳纤毛虫群落进行聚类分析, 得到两个群落(相似度30%): 群落I(7-9月)和群落II(3-6月、10-11月), 说明砂壳纤毛虫群落发生了明显的季节变化。砂壳纤毛虫的物种丰富度、丰度与环境因子(温度、盐度)均没有明显的相关性。     

世界今生砂壳纤毛虫名录

砂壳纤毛虫隶属于纤毛门、旋毛纲、环毛亚纲、砂壳目.本文总结了自Kofoid和Campbell(1929)以来的分类学资料,参照Lynn(2008)的分类系统,整理成世界砂壳纤毛虫新名录.厘清砂壳纤毛虫共有15科69属954种,其中海洋种为15科69属925种,淡水种为3科5属29种.在所有属中,以拟铃虫属(Tintinnopsis包含物种最多,为137种,其中海洋种为118种.我国水体共记录有13科36属164种,海洋种13科36属144种,淡水种2科3属20种.除杯形铃壳虫(Codonella cratera)、湖泊领细壳虫(Stenosemella lacustris)、蜉蝣筒壳虫(Tintinnidium ephemeridum)、蝌蚪筒壳虫(Tintinnidium ranunculi)、半缘筒壳虫(Tintinnidium semiciliatum)、纺锤拟铃虫(Tintinnopsis fusiformis)、伊利诺拟铃虫(Tintinnopsis illinoisensis)、卵圆拟铃虫(Tintinnopsis ovalis)、圆柱拟铃虫(Tintinnopsis cylindrata)、这9个种外,其他淡水种在我国都有记录.该名录中,除了已有中文名的159种外,其余的种我们给出了中文译名,并将部分译为似铃虫属(Tintinnopsis)的中文名统一为拟铃虫属,部分译为麻铃虫属(Leprotintinnus)的中文名统一为薄铃虫属,将截短角口虫(Salpingella decurtata)改为截短号角虫,将冰生拟铃壳虫(Codonellopsis glacialis)改为冰生类铃虫.     

Temporal variation in different life stages of moths (Lepidoptera) from a southwestern temperate forest of Korea: A preliminary study

Two study sites in a temperate forest in Mt. Seungdal-san, Muan, Jeonnam in southwestern Korea were selected for the collection of caterpillars and adult moths (Lepidoptera). Here, we determined (1) the characteristics of moth fauna based on lepidopteran larvae and adults, and (2) the differences in temporal variation between these two developmental stages. In addition, we investigated the life history of moth species collected at the surveyed sites. Of the 206 caterpillars collected, 17 moth species from 9 families were successfully reared. A total of 342 adult moth species and 2108 individuals from 15 families were collected. Twenty-two plants were identified as host plants of 188 caterpillars. Two tree species, Prunus serrulata var. spontanea and Quercus serrata, were widely distributed in the study sites. Leaf water content (%) of Quercus serrata and Carpinus laxiflorawas the highest in June, whereas the leaf water content of Platycarya strobilacea was the highest in August. We postulated that many of the variables in the temperate forest, such as host plant availability, parasitoids, disease, and weather, affected the lepidopteran caterpillar populations. There were differences in species composition among the sampling methods which suggest the need for diverse methods to uncover total biodiversity. However, it should be noted that a long term and well-planned study with efficient rearing of caterpillars is needed to better understand these correlations.     

Salt marsh plants carbon storage in a temperate Atlantic estuary illustrated by a stable isotopic analysis based approach

The biomasses, carbon standing stocks, and exportations of three saltmarsh species – Scirpus maritimus, Spartina maritima and Zostera noltii – were determined and their isotopic composition analyzed to illustrate their role in carbon storage in a temperate Atlantic estuary (Mondego, Portugal). Biomass values were higher in the warmer seasons than in the cold seasons, with carbon contents following the same trend. Carbon content ranged from 27–39% in S. maritimus and S. maritima to 30–39% for Z. noltii. S. maritimus had the highest carbon production in the aboveground organs and had similar results with S. maritima in the belowground carbon production. These three species together occupied about 50% of the salt marsh area and they stored in 21 months of study 24,000 kg of carbon in their aboveground and belowground organs. Z. noltii presented highest carbon concentration in the sediment and S. maritimus the lowest. Stable carbon isotopic analysis showed that apparently, the sedimentary organic matter is composed by a mix of terrestrial sources, macro and microalgae. Regard the high carbon exportation, S. maritima and Z. noltii are constantly accumulating carbon. The studied species have both a sink and source behaviour simultaneously.     

Temporal and spatial structure in the suprabenthic community of a shallow estuary (western Portugal: Mondego river estuary)

The suprabenthic fauna of the Mondego river estuary (western Portugal) was sampled monthly between June 1996 and June 1997. Quantitative samples were taken, with a suprabenthic 500-μm mesh size net, at regularly spaced stations covering the entire south arm of the estuary. The diversity of the samples and the distribution of the species were assessed. Suprabenthic communities were identified using a divisive multivariate statistical technique and species composition, density and biomass of the dominant species of each community were compared among communities. Diversity was highest in the mouth of the estuary where density and biomass were lowest. Diversity decreased upstream and was lowest in the mid and inner estuary where density and biomass reached maximal values. Suprabenthic animals, mainly the mysid Mesopodopsis slabberi, reached high densities in inner and upstream stations, whereas the more seaward stations had lower densities but a higher number of species. The spatial patterns dominated over the temporal patterns.     

Zooplankton distribution and dynamics in a temperate shallow estuary

The spatial, temporal and tidal dynamics of the zooplanktonic community of the Mondego estuary was studied from January 2003 to 2004. The monthly sampling procedure included the measurement of hydrological parameters (salinity, temperature, Secchi transparency, chlorophyll a and nutrients) and the collection of zooplankton with a Bongo net of 335 μm mesh size. Zooplankton composition, distribution, density, biomass and diversity were determined. The principal component analysis (PCA) revealed the existence of a spatial gradient with the upstream sampling stations, associated to high values of nutrients, in opposition to the downstream stations characterized by higher salinity and transparency values. The Copepoda was the main dominant group and Acartia tonsa revealed to be the more abundant taxon. The spatial and temporal dynamics of zooplanktonic communities analysed by non-metric MDS showed the existence of four assemblages of species-sites, reflecting differences in zooplankton composition between both branches of the estuary. The results suggest that abundance, biomass and diversity of the zooplanktonic community are strongly influenced by the hydrological circulation pattern and by direct or indirect human impacts that occur in each branch. The northern branch is dominated by the river flow suffering from regular dredging activities and the southern branch is dominated by tidal circulation suffering from an ongoing eutrophication process.     

A comparative ultrastructural study on the nanoscale extrusomes of tintinnids (Alveolata,Ciliophora, Spirotricha) and their phylogenetic significance

The capsules, putative extrusomes in tintinnid ciliates, are known since 1971. Based on their ultrastructure, shape, and size, five capsule types were distinguished and suggested to be of phylogenetic significance. However, detailed morphometric data and transmission electron micrographs are lacking to verify former conclusions. In the current study, comprehensive analyses of transmission electron microscopic data were performed, investigating 14 species from 13 genera and more than seven families collected in European coastal waters and in the Northeast Pacific. Our data suggest two main capsule types (large and ampulliform vs small and ellipsoidal/ovoidal) each including two subtypes characterised by their internal structures. Species groupings inferred from the capsule (sub-)types emerge also as closely related in gene trees. Additionally, the ampulliform type unites the Undellidae, Xystonellidae, and Tintinnid clade 2, while the shared possession of the small ellipsoidal type proposes a close relationship of Tintinnid clade 11 with the Rhabdonellidae and Cyttarocylididae. Thus, the capsules provide promising features to shed light on several unresolved evolutionary relationships among tintinnid genera and families; yet, information on capsules is still missing for many monophyletic groupings. Finally, we provide the first ultrastructural clues for the extrusive character of these organelles.     

Temporal variability in the diversity and composition of stream bacterioplankton communities

Bacterioplankton in freshwater streams play a critical role in stream nutrient cycling. Despite their ecological importance, the temporal variability in the structure of stream bacterioplankton communities remains understudied. We investigated the composition and temporal variability of stream bacterial communities and the influence of physicochemical parameters on these communities. We used barcoded pyrosequencing to survey bacterial communities in 107 streamwater samples collected from four locations in the Colorado Rocky Mountains from September 2008 to November 2009. The four sampled locations harboured distinct communities yet, at each sampling location, there was pronounced temporal variability in both community composition and alpha diversity levels. These temporal shifts in bacterioplankton community structure were not seasonal; rather, their diversity and composition appeared to be driven by intermittent changes in various streamwater biogeochemical conditions. Bacterial communities varied independently of time, as indicated by the observation that communities in samples collected close together in time were no more similar than those collected months apart. The temporal turnover in community composition was higher than observed in most previously studied microbial, plant or animal communities, highlighting the importance of stochastic processes and disturbance events in structuring these communities over time. Detailed temporal sampling is important if the objective is to monitor microbial community dynamics in pulsed ecosystems like streams.     

Temporal variability in detritus resource maintains diversity of bacterial communities

Competition theory generally predicts that diversity is maintained by temporal environmental fluctuations. One of the many suggested mechanisms for maintaining diversity in fluctuating environments is the gleaner-opportunist trade-off, whereby gleaner species have low threshold resource levels and low maximum growth rates in high resource concentration while opportunist species show opposite characteristics. We measured the growth rates of eight heterotrophic aquatic bacteria under different concentrations of chemically complex plant detritus resource. The growth rates revealed gleaner-opportunist trade-offs. The role of environmental variability in maintaining diversity was tested in a 28-day experiment with three different resource fluctuation regimes imposed on two four-species bacterial communities in microcosms. We recorded population densities with serial dilution plating and total biomass as turbidity. Changes in resource availability were measured from filter-sterilised medium by re-introducing the consumer species and recording short-term growth rates. The type of environmental variation had no effect on resource availability, which declined slowly during the experiment and differed in level between the communities. However, the slowly fluctuating environment had the highest Shannon diversity index, biomass, and coefficient of variation of biomass in both communities. We did not find a clear link between the gleaner-opportunist trade-off and diversity in fluctuating environments. Nevertheless, our results do not exclude this explanation and support the general view that temporal environmental variation maintains species diversity also in communities feeding chemically complex resource.     

Temporal variability of foliar nutrients: responses to nitrogen deposition and prescribed fire in a temperate steppe

Plant nutrient concentrations and stoichiometry drive fundamental ecosystem processes, with important implications for primary production, diversity, and ecosystem sustainability. While a range of evidence exists regarding how plant nutrients vary across spatial scales, our understanding of their temporal variation remains less well understood. Nevertheless, we know nutrients regulate plant function across time, and that important temporal controls could strongly interact with environmental change. Here, we report results from a 3-year assessment of inter-annual changes of foliar nitrogen (N) and phosphorus (P) concentrations and stoichiometry in three dominant grasses in response to N deposition and prescribed fire in a temperate steppe of northern China. Foliar N and P concentrations and their ratios varied greatly among years, with this temporal variation strongly related to inter-annual variation in precipitation. Nitrogen deposition significantly increased foliar N concentrations and N:P ratios in all species, while fire significantly altered foliar N and P concentrations but had no significant impacts on N:P ratios. Generally, N addition enhanced the temporal stability of foliar N and decreased that of foliar P and of N:P ratios. Our results indicate that plant nutrient status and response to environmental change are temporally dynamic and that there are differential effects on the interactions between environmental change drivers and timing for different nutrients. These responses have important implications for consideration of global change effects on plant community structure and function, management strategies, and the modeling of biogeochemical cycles under global change scenarios.     

Phylogeography of Agathistoma (Turbinidae,Tegulinae) snails in tropical and southwestern Atlantic

The rocky intertidal gastropods Agathistoma viridulum and A. hotessierianum occur from the Caribbean to southern Brazil, with a gap in the equatorial region, giving them an anti-tropical distribution. We used sequences from mitochondrial genes to elucidate the phylogeography of A. viridulum and A. hotessierianum and to infer their relationships to other species of Agathistoma. For A. hotessierianum, haplotype networks and phylogenetic analyses split samples into two distinct groups: one (A. hotessierianum) in the Caribbean region (Greater and Lesser Antilles; Venezuela: Sucre and Isla Margarita) and a new species that we describe from northeastern Brazil. For A. viridulum, genetic analyses split the samples into three groups (Caribbean, northeastern Brazil and southeastern Brazil), but genetic divergence among these was too low for them to be considered species, and morphological differences were not significant. The mtDNA tree identified two clades of eastern Pacific Agathistoma, but many lower-level relationships within Agathistoma were not well resolved, suggesting that more complete taxon sampling and additional genetic data will be needed to establish more robust relationships among Tegulinae.     

Diatom ecological preferences in a shallow temperate estuary (Ria de Aveiro,Western Portugal)

The study of the diatom ecological preferences was conducted from January 2002 to June 2003 in Canal de Mira, Ria de Aveiro, Western Portugal. Three sampling stations along a salinity gradient were sampled monthly, in new moon, at high and low tide. Salinity, temperature, pH, dissolved oxygen and nutrient contents were measured for each sampling station; chlorophyll a and diatom diversity and abundance were also evaluated. Canonical correspondence analysis was used to identify the environmental variables governing the composition and structure of diatom assemblage. The variation in the species data among the different reaches was strongly determined by the salinity spatial gradient and by the temperature temporal gradient. The lower reaches were dominated by marine species (e.g. Auliscus sculptus, Chaetoceros densus, Fallacia forcipata,Licmophora flabellata, L. grandis, Surirella comis), while in the most upstream station typical freshwater species dominated (e.g. Caloneis permagna, Cymatopleura solea, Cymbella tumida, Gomphonema longiceps, Pinnularia stommatophora, Stauroneis smithii). Weighted averaging was used to estimate optima and tolerances of some diatom taxa for the most influential variables. It was possible to establish groups oftaxa with defined and distinctive salinity and temperature preferences.     

Growth rate variability in geographically diverse clones of Uronema (Ciliophora: Scuticociliatida)

Abstract Growth rates in 15 clones from the bacterivorous ciliate Uronema and one from Parauronema acutum have been compared under similar culture conditions. Five species were identified on a morphological basis: U. marinum, U. nigricans, U. elegans, P. acutum , and an undescribed form designated here as SWi1 . Intra- and inter-specific distinct growth characteristics were observed. Net cellular production tended to decrease with lower growth rate in different species or morphotypes but increased in those clones belonging to the same species. Growth rate and cell volume were not significatly correlated although mean growth rate increased with mean cell volume. Growth rate was however significantly correlated to the relative variation in cell volume between different growth phases. Estimation of growth rates using different models indicated that the experimental growth rates observed were not significatly different from those expected for the cell volumes. These results indicate how effects of habitat or geographical variability, in this cosmopolitan genus, may account for trophodynamic variation of morphologically similar species.     

Seasonal variations of tintinnids (Ciliophora: Oligotrichida) in Narragansett Bay, Rhode Island, U.S.A.

Tintinnids exhibit a bimodal peak of abundance in NarragansettBay, with a minimum in late spring and a lesser peak in latesummer-early autumn, depending on location. Thirty-three speciesin eight genera were identified, with the fauna dominated bythe genus Tintinnopsis. Tintinnid abundance was not obviouslycorrelated with salinity, temperature, or nanoplankton chlorophyllconcentration. Patterns of change in seasonal abundance canserve as a framework for posing additional questions of therole tintinnids play in marine food webs.