An approach to determining the sampling effort for analyzing biofilm-dwelling ciliate colonization using an artificial substratum in coastal waters

A new approach to determining sampling effort for analyzing biofilm-dwelling ciliate colonization was studied in the coastal waters of the Yellow Sea, northern China, from May to June 2010. The optimal sample size for evaluating biofilm-dwelling ciliate colonization increased with shortening exposure time, and can be determined according to the probability of recovering those species with a specified cumulative contribution to communities. More slide-replicates were required at a depth of 3 m than at 1 m to recover equivalent proportions of the ciliate communities. For routine colonization dynamics analyses, 10 slide-replicates (175 cm²) were sufficient to achieve a 95% probability of recovering those species with a cumulative contribution of >90% to the ciliate communities at a depth of 1 m. These results suggest that 10 slide-replicates immersed at a depth of 1 m may be an optimal sampling strategy for analyzing the colonization dynamics of biofilm-dwelling ciliate communities in marine habitats.     

Trophic-functional patterns of biofilm-dwelling ciliates at different water depths in coastal waters of the Yellow Sea,northern China

Vertical variations in trophic-functional patterns of biofilm-dwelling ciliates were studied in coastal waters of the Yellow Sea, northern China. A total of 50 species were identified and assigned to four trophic-functional groups (TFgrs): algivores (A), bacterivorous (B), non-selective (N) and raptors (R). The trophic-functional structures of the ciliate communities showed significant variability among different water depths: (1) with increasing water depth, relative species numbers and relative abundances of groups A and R decreased sharply whereas those of groups B and N increased gradually; (2) in terms of the frequency of occurrences, group A dominated at depths of 1–3.5 m whereas group B dominated at 5 m, while in terms of the probability density function of the trophic-functional spectrum, group A was the highest contributor at 1 m and group B was highest at the other three depths; (3) distance-based redundancy analyses revealed significant differences in trophic-functional patterns among the four depths, except between 2 and 3.5 m (P > 0.05); and (4) the trophic-functional trait diversity increased from 1 to 3.5 m and decreased sharply at 5 m. Our results suggest that the biofilm-dwelling ciliates maintain a stable trophic-functional pattern and high biodiversity at depths of 1–3.5 m.     

Responses of Biofilm-Dwelling Ciliate Communities to Planktonic and Benthic Resource Enrichment

Four experiments covering different seasons were performed to test the impact of increased benthic and planktonic resource availability on the structure of biofilm-dwelling ciliate communities which were cultivated in river bypass systems. The growth of benthic bacteria was stimulated by the addition of dissolved organic carbon. The enrichment of the planktonic resource was achieved by supplementation with suspended bacteria. It was shown that both resource enrichments can differentially influence abundance and taxonomic structure of ciliate communities. Furthermore, both resources can influence different stages during biofilm colonization. Increased benthic bacterial growth mainly resulted in both an accumulation of primarily grazing-resistant bacterial filaments and in an increase in the number of vagile heterotrophic flagellates. This can stimulate nanophagous ciliates (feeding on flagellates) in addition to the direct stimulation of bacteriovorous ciliates. The effects of the planktonic bacteria enrichments were twofold: They could have been utilized either directly by suspension-feeding ciliates or indirectly through an enhanced growth of suspension-feeding attached heterotrophic flagellates, which were then in turn grazed upon by ciliates. The magnitude of responses of the total ciliate abundance to the two resource enrichments further depended on the background conditions, thereby showing temporarily variable limitations of these resources. Furthermore, the particular taxonomic groups stimulated by one resource type sometimes differed between the experiments, an observation which demonstrates that the response depends on different environmental factors and is not easily predictable based simply on resource type. Taken together, our results emphasize the need of a differentiated view on the effects of resources on complex biofilm-dwelling consumer communities with respect to both the origin of carbon source as well as the particular environmental conditions.     

Uncertain biotic and abiotic interactions in benthic communities

We analyze marine benthic communities at different sites in Skagerrak with the purpose of understanding the role of exogenous and endogenous factors in explaining the species' temporal dynamics. The previous finding that the dynamics of these species communities are mainly driven and synchronized by environmental (temperature) forcing was only weakly supported when analyzing single-species dynamics at five sites where four of the species were present every year. There was no consistent pattern in how the temperature affected the realized per capita growth rate, either across species at a given site, or among sites for a given species. Furthermore, there was no net-interaction from the community on a given species strong enough to give rise to second-order dynamics. However, when implementing a Multi Dimensional Scaling (MDS) analysis and incorporating all sampling sites and species -we found that the different communities clustered in relation to depth, hence, communities at the same depth were more "similar" than communities at different depth. Revealing the underlying interactions shaping these marine benthic communities is a challenge that calls for an array of various and complementary approaches.     

甘肃定西华家岭土壤纤毛虫群落对生态恢复的响应

为了解土壤纤毛虫群落对生态恢复下的土壤环境的响应,于2007年9月—2008年8月用活体观察法和"三级十倍环式稀释法"对甘肃定西华家岭5个不同恢复阶段的人工云杉林和1个荒草坡对照点的土壤纤毛虫群落以及季节动态进行了研究,探讨了土壤纤毛虫群落组成对生态恢复下土壤环境的相关性。共鉴定到127种纤毛虫,隶属于3纲9目34科50属。研究发现,各不同恢复年限土样中土壤纤毛虫的物种分布存在明显差异,并随恢复时间的延长,样点间物种相似性减小,群落组成复杂化,丰度、物种数和物种多样性指数均呈上升趋势。优势类群也发生了响应,由I号对照样点和恢复初期II号样点的肾形目变为恢复后期样点的下毛目。结果显示,土壤纤毛虫群落动态很好地响应了生态恢复过程中土壤环境条件的变化。土壤纤毛虫群落可用于陆地生态恢复评价,但要建立有效可行的、具有普遍意义的评价指标体系,尚需大量的和系统的工作。     

Stratification and dynamics of microbial loop communities in Lake Fryxell, Antarctica

1. Lake Fryxell, situated in the McMurdo Dry Valleys, Antarctica, offers the opportunity to study microbial loop processes in the absence of crustacean zooplankton and other higher organisms. This is the first study of Lake Fryxell to provide detailed temporal and vertical variations of microbial loop organisms.
2. Protozoan communities are concentrated around the chemocline (9–10 m) in Lake Fryxell. Phototrophic nanoflagellates (PNAN), heterotrophic nanoflagellates (HNAN) and ciliates formed deep maxima of 14 580, 694 and 58 cells mL−1 respectively. Although abundance and biomass at the chemocline was high, diversity of protozoa was low, Plagiocampa accounting for> 80% of the total ciliate biomass.
3. In the mixolimnion (4.5–8 m), protozoa were less abundant, but more diverse, with 24 ciliate morphotypes being identified within this region of the water column. Inter-annual variability of protozoan biomass and abundance was greater in the mixolimnion than at the chemocline due to more variable nutrient and prey concentrations.
4. Physicochemical gradients in Lake Fryxell were very stable because the perennial ice cover reduced wind driven currents. As a consequence, ciliate species occurred in distinct depth strata, Monodinium being most abundant directly beneath the ice cover, Askenasia having maximum abundance at 8 m and Plagiocampa dominating ciliate biomass at the chemocline. The lack of vertical mixing reduced seasonal successions of PNAN and ciliate species. Three cryptophyte species dominated the PNAN community at all times (>79% of total biomass).     

Community structure and seasonal dynamics of planktonic ciliates along salinity gradients

The ciliate community structure and seasonal dynamics in a solar saltern of the Yellow Sea were studied based on 4 sampling dates and 8 stations with salinities from 27.7‰ to 311.0‰. The effects of the type and concentration of the fixative used (Lugol's and Bouin's) were tested at the first sampling date. Fixative type and fixative concentration had significant effects on ciliate abundance and biovolume, with 1% Lugol's giving the best results. A detailed investigation using live observations and protargol staining techniques revealed a total of 98 morphospecies from 8 sampling stations. There was obvious seasonal variation in species composition at most of the stations, but this tended to be less distinct with increasing salinity, as the dominant ciliate group shifted from oligotrichs to heterotrichs. Ciliate abundance varied from 4.40×10¹ to 2.11×10⁵ cells l^?1 and biomass ranged between 2.39 and 9.87×10³ μg C l^?1 (at a salinity of 147.6‰). Both abundance and biomass decreased abruptly when salinity exceeded 100–150‰. Statistical analyses suggested that the dynamics of ciliate abundance and biomass were regulated by both salinity and by season, but those of diversity and species richness were mainly controlled by salinity and both significantly decreased with increasing salinity.     

沙坡头地区沙冬青AM真菌的时空分布

2007年5月、8月和10月分别从宁夏沙坡头地区豆科植物沙冬青(Ammopiptanthus mongolicus)根围分0-10cm,10-20cm,20-30cm,30-40cm和40-50cm5个土层采集土壤样品。研究了AM真菌时空分布及与土壤因子的相关性,在分离的3属12种AM真菌中,球囊霉属(Glomus)6种,无梗囊霉属(Acaulospora)4种,盾巨孢囊霉属(Scutellospora)2种,3属12种AM真菌在3个时期均有分布。AM真菌定殖率与孢子密度有明显的时空分布规律,并与土壤因子关系密切。孢子密度和泡囊定殖率在8月份最高,丛枝、菌丝和总定殖率10月份最高。土壤采样深度对孢子密度和定殖率有显著影响,AM真菌最高定殖率和最大孢子密度均出现在0-30cm浅土层。孢子密度与土壤有机质、碱解N极显著正相关,与pH显著正相关;菌丝、总定殖率与pH、碱解N和速效P极显著正相关。在评估荒漠生态系统和沙冬青形成菌根的能力时,AM真菌孢子密度、菌根不同结构的定殖程度是十分有用的指标。     

Winter Ciliates in a British Columbian Fjord: Six New Species and an Analysis of Ciliate Putative Prey

ABSTRACT. This work provides the first study of North Pacific planktonic ciliates by quantitative protargol staining. Triplicate water bottle samples were collected at a depth of 2 m (above the shallow pycnocline) at six stations in Indian Arm, British Columbia, on February 15, 1990, and February 26, 1991. Thirty-six ciliate species were observed. Six new species are described from protargolstained specimens: Strombidium lynni n. sp., Strombidium taylori n. sp., Strombidium basimorphum n. sp., Slrombidiurn ventropinnum n. sp., Strobilidium undinum n. sp., and Urotricha cyrtonucleata n. sp.
Ciliate abundance varied significantly (ANOVA, α= 0.05) between sampling sites, ranging from 550 to 6,800 cells/liter in 1990 and from 1,800 to 7,900 cells/liter in 1991. Biomass also varied significantly (ANOVA, α= 0.05) ranging from 3.7 × 10⁵ to 3.3 × 10⁶ pg carbon/liter in 1990 and 3.04 × 10⁶− 6.97 × 10⁶ pg carbon/liter in 1991. Putative prey were enumerated in three size fractions (1.5–5 μm, 5–10 μm and 10–25 μm). The source of variation in ciliate abundance and biomass was not identified. Parameters of salinity, temperature, putative prey, chlorophyll a and pycnocline depth did not significantly correlate with ciliate biomass or abundance (α= 0.05).     

Breeding birds on small islands: island biogeography or optimal foraging?

1. We test MacArthur and Wilson's theory about the biogeography of communities on isolated habitat patches using bird breeding records from 16 small islands off the coasts of Britain and Ireland. 2. A traditional examination of patterns of species richness on these islands suggests that area and habitat diversity are important predictors, but that isolation and latitude have a negligible impact in this system. 3. Unlike traditional studies, we directly examine the fundamental processes of colonization and local extinction (cessation of breeding), rather than higher-order phenomena such as species richness. 4. We find that many of MacArthur and Wilson's predictions hold: colonization probability is lower on more isolated islands, and extinction probability is lower on larger islands and those with a greater diversity of habitats. 5. We also find an unexpected pattern: extinction probability is much lower on more isolated islands. This is the strongest relationship in these data, and isolation is the best single predictor of colonization and extinction. 6. Our results show that examination of species richness alone is misleading. Isolation has a strong effect on both of the dynamic processes that underlie richness, and in this system, the reductions in both colonization and extinction probability seen on more distant islands have opposing influences on species richness, and largely cancel each other out. 7. We suggest that an appropriate model for this system might be optimal foraging theory, which predicts that organisms will stay longer in a resource patch if the distance to a neighbouring patch is large. If nest sites and food are the resources in this system, then optimal foraging theory predicts the pattern we observe. 8. We advance the hypothesis that there is a class of spatial systems, defined by their scale and by the taxon under consideration, at which decision-making processes are a key driver of the spatiotemporal dynamics. The appropriate theory for such systems will be a hybrid of concepts from biogeography/metapopulation theory and behavioural ecology.     

Spatial Distribution of Algal Assemblages in a Temperate Lowland Peat Bog

Samples of phytobenthos were collected during three different seasons in 2005 along a linear transect of a lowland peat bog at various spatial scales (10 cm, 1 m, 10 m) to investigate the seasonal dynamics, diversity, and factors influencing the spatial patterns of microalgal communities. Non‐metric multidimensional scaling (NMDS), similarity percentage (SIMPER) analyses, ANOSIM, Mantel tests and diversity indices were used to analyze the data. Seasonal dynamics were exhibited by an increase in diversity, and a decrease in dominance from May to October, with significant differences in species composition. Mantel tests showed the significant influence of distance, microhabitat type, and conductivity on maintaining the similarity of species composition on scales of 1 m and 10 m. The small‐scale processes (colonization and niche differentiation), microhabitat type, geographic distance and conductivity were found to be the main factors influencing the distribution of algal assemblages. We conclude that these factors are related to winter disturbance, and the consequent colonization and subsequent niche differentiation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

An approach to analyzing spatial patterns in annual dynamics of planktonic ciliate communities and their environmental drivers in marine ecosystems

The environmental drivers to shape the spatial patterns in annual dynamics of the planktonic ciliate communities were studied based on an annual dataset from a bay, northern Yellow Sea. Samples were biweekly collected at five stations with different environmental condition status during a 1-year period. The second-stage-analysis-based multivariate approaches were used to reveal the internal dynamics in annual patterns of the ciliate assemblages. Results showed that: (a) there was a clear spatial variability in annual dynamics among five stations; (b) the dominant species represented different succession dynamics among four samples stations during the 1-year cycle; and (c) the spatial variations in annual patterns of the ciliates were significantly correlated with nutrients, alone or in combination with salinity and dissolve oxygen (DO). Thus, it is suggested that the nutrients may be the main drivers to shape the spatial patterns in annual dynamics of planktonic ciliate communities in marine ecosystems.     

A new method for evaluating defense of microalgae against protozoan grazing

Body-size spectrum has proved to be a highly informative indicator to summarize the functional structure of a community at taxon-free resolution. In this study, an approach based on body-size spectrum of protozoan communities was used to detect the defense of microalgae against protozoan grazing. The biofilm-dwelling protozoan communities were used as a test predator system, and two algal species, Chlorella sp. and Nannochloropsis oceanica, were employed as test microalgae. A nine-day bioassay test was carried out by exposing biofilm-dwelling protozoan communities to a gradient of concentrations 10⁰ (control), 10⁴, 10⁵, 10⁶, and 10⁷ cell ml⁻¹ of both microalgae, respectively. Results showed that both algal species represented strong defense effects on the test predator system at different levels of concentration. The body-size distinctness of the protozoan assemblages showed a sharp decrease at high concentration level more than 10⁶ cell ml⁻¹ in both algal treatments. Based on the paired body-size distinctness indices of the protozoa, ellipse tests demonstrated that the body-size spectrum showed an increasing trend of departure from the expected pattern with increasing concentrations of both test algae. Thus, it is suggested that the body-size spectrum of protozoa may be used as a useful indicator to identify the defense of microalgae against protozoan grazing.     

土壤纤毛虫群落对退牧还草生态恢复的响应——以玛曲县为例

为研究退牧还草对土壤纤毛虫群落特征的影响、退牧还草后土壤环境变化以及如何利用原生动物纤毛虫群落特征来评价退还效果的可行性,于2015年5月至2016年3月在甘肃省甘南藏族自治州玛曲县选取3个不同恢复年限的草地样点和1个未经过退牧还草对照样点,采用"非淹没培养皿法"、活体观察法和培养直接计数法对土壤纤毛虫的物种数和密度进行测定,同时测定了土壤温度、pH值、含水量、土壤孔隙度、速效钾、速效氮、速效磷、全氮、全钾、全磷和有机质含量,并分析了在生态逐渐恢复条件下,土壤纤毛虫群落特征与土壤环境因子间的相关性。研究共鉴定到纤毛虫95种,隶属9纲15目21科28属。研究发现,退牧还草样地与未退牧还草样地的土壤纤毛虫的物种分布存在明显差异:退牧还草后的3个样点间的物种相似性减小,群落组成复杂化,纤毛虫丰度、丰富度指数、均匀度指数和物种多样性指数增高。相关性分析结果表明,退牧还草后,对纤毛虫群落结构稳定性影响最主要的是土壤有机质、含水量和土壤全氮、全磷和全钾的含量,不同恢复年限样点的土壤纤毛虫群落组成差异较大。土壤纤毛虫群落对退牧还草生态恢复过程中土壤环境条件的变化有较好的响应。     

An approach to identifying potential surrogates of periphytic ciliate communities for monitoring water quality of coastal waters

For identifying the potential surrogate of periphytic ciliate communities for monitoring marine water quality, the different taxonomic resolutions/taxa as surrogates and different data transformations were studied based on two datasets of ciliate communities in Korean coastal waters. Multivariate analyses showed that: (1) a dominant Zoothamnium duplicatum significantly masked the temporal patterns of periphytic ciliate community; (2) the order level resolution maintained sufficient information to evaluate the efficient patterns of ciliate communities in response to environmental impacts; (3) the vagile-ciliate assemblage at species-level resolution was as costly as whole periphytic ciliate communities without Z. duplicatum at the order level; and (4) the severity of data transformations played a crucial role for effectiveness of surrogates, e.g., heavy transformation for species level and mild for higher. These results suggest that the use of lower taxonomic resolutions is time-efficient and would allow improving sampling strategies of large spatial/temporal scale monitoring researches in the marine ecosystem.     

Seasonal variations in colonization dynamics of periphytic protozoa in coastal waters of the Yellow Sea,northern China

The colonization features of periphytic protozoa have proved to be a useful tool for indicating water quality status in aquatic ecosystems. In order to reveal the seasonal variations in colonization dynamics of the protozoa, a 1-year baseline survey was carried out in coastal waters of the Yellow Sea, northern China. Using glass slides as artificial substrates, a total of 240 slides were collected at a depth of 1 m in four seasons after colonization periods of 3, 7, 10, 14, 21, and 28 days. A total of 122 ciliate species were identified with 21 dominant species. The colonization dynamics of the protozoa were well fitted to the MacArthur-Wilson and logistic models in all four seasons (P < 0.05). However, the equilibrium species numbers (S_eq), colonization rates (G), and the time to 90% S_eq (T_90%) represented a clear seasonal variability: (1) more or less similar levels in spring and autumn (S_eq = 29/23; G = 0.301/0.296; T_90%=7.650/7.779); (2) with a significant difference in summer and winter (S_eq = 32/121; G = 0.708/0.005; T_90% = 3.252/479.705). Multivariate approaches demonstrated that the exposure time for the species composition and community structure of the protozoa to an equilibrium period were 10–14 days in spring and autumn, but less and more time periods were needed in summer and winter, respectively. Based on the results, we suggest that the colonization dynamics of periphytic protozoa were different within four seasons, and an optimal sampling strategy for monitoring surveys should be modified during different seasons in marine ecosystems.     

Effects of Spilled Oil on Bacterial Communities of Mediterranean Coastal Anoxic Sediments Chronically Subjected to Oil Hydrocarbon Contamination

The effects of spilled oil on sedimentary bacterial communities were examined in situ at 20 m water depth in a Mediterranean coastal area. Sediment collected at an experimental site chronically subjected to hydrocarbon inputs was reworked into PVC cores with or without a massive addition of crude Arabian light oil (∼20 g kg⁻¹ dry weight). Cores were reinserted into the sediment and incubated in situ at the sampling site (20 m water depth) for 135 and 503 days. The massive oil contamination induced significant shifts in the structure of the indigenous bacterial communities as shown by ribosomal intergenic spacer analysis (RISA). The vertical heterogeneity of the bacterial communities within the sediment was more pronounced in the oiled sediments particularly after 503 days of incubation. Response to oil of the deeper depth communities (8–10 cm) was slower than that of superficial depth communities (0–1 and 2–4 cm). Analysis of the oil composition by gas chromatography revealed a typical microbial alteration of n-alkanes during the experiment. Predominant RISA bands in oiled sediments were affiliated to hydrocarbonoclastic bacteria sequences. In particular, a 395-bp RISA band, which was the dominant band in all the oiled sediments for both incubation times, was closely related to hydrocarbonoclastic sulfate-reducing bacteria (SRB). These bacteria may have contributed to the main fingerprint changes and to the observed biodegradation of n-alkanes. This study provides useful information on bacterial dynamics in anoxic contaminated infralittoral sediments and highlights the need to assess more precisely the contribution of SRB to bioremediation in oil anoxic contaminated areas.     

Use of Protozoan Communities to Predict Environmental Effects of Pollutants1

ABSTRACT. This study compared the response of protozoan communities colonizing artificial substrates to complex effluents in laboratory microecosystems and validated laboratory predictions using similar sampling methods in the field. Sampling stations were established on a small stream receiving heavy metal and sewage treatment plant effluents. Water from each station was used as a test medium to test the colonization of polyurethane foam artificial substrates in laboratory microecosystems. The heterotrophic index (HI), the ratio of total community biomass to chlorophyll biomass, was also measured. Field colonization trials and HI determinations were carried out at each sampling station. There was a strong negative relationship between the number of species colonizing artificial substrates and the total metal concentration of the water at each station; protozoan colonization was severely depressed at the highest metal concentrations (>400 μg/liter) and recovered at downstream stations where dilution had taken place. The HI differentiated stations receiving high heavy metal concentrations in the field from those recovering from heavy metal influences. Effect concentrations based on laboratory experiments predicted that the concentration of total heavy metal that would produce a 5% decrease in species number (EC5) was 18 μg/liter, approximately the background concentration found in the stream studied. These experiments demonstrated that laboratory microecosystems or microcosms can be used to predict effects in the field accurately.     

Ciliate communities in shallow groundwater: seasonal and spatial characteristics

1. Ciliated protozoans (Phylum Ciliophora) were collected from five sites in a shallow groundwater system in southern Ontario, Canada over a 13‐month period: one at the spring source, two along the channel banks, and two in the stream channel. Ciliates and environmental data were collected from surface water and at five depths into the sediment, located at 20, 40, 60, 80 and 100 cm. 2. Species richness was high (170 ciliate species belonging to 89 genera were identified) and variable, both spatially and temporally. Highest species richness (86) occurred between 20 and 60 cm, and typically decreased below 60 cm. 3. Ciliate densities were also seasonally and spatially variable. Densities peaked in March between 40 cm (as high as 69 900 cells L⁻¹) and 60 cm, and again in May and June at 80 and 100 cm. Densities were lowest in winter. The surface‐water ciliate community had a different species composition and lower population densities. 4. At all depths, small (<50 μm) bacterivorous ciliates typically dominated, but omnivorous and predatory species were also present (combined, up to 30% of the average density). 5. Several ciliate genera, traditionally considered planktonic, occurred at low densities from 40 cm down to 100 cm. 6. Ordination analysis indicated that the main factors influencing the shallow groundwater ciliate communities were depth and temperature. 7. Dissolved oxygen also appeared to influence these communities in that they typically comprised genera that preferred either low‐oxygen or anaerobic conditions.     

Ecological,Dynamic and Taxonomic Problems Due to <Emphasis Type="Italic">Ludwigia</Emphasis> (Onagraceae) in France

We analyzed meta-community structure of bdelloid rotifers colonizing mosses along an 80 meter section of Rio Valnava in NW Italy. Bdelloid rotifers are small animals living associated with a substratum; colonization in bdelloids can be produced by active animals moving along the riverbed, or by passive dormant propagules, moved by wind. To detect which kind of colonization might be stronger at different spatial scales, we designed a spatially nested sampling experiment at three hierarchical levels: (1) single sample, (2) 10 communities inside each pool, (3) complete section of 10 pools. Assessing species richness and species similarity of communities, and coherence and nestedness of bdelloid meta-communities, we found that different forces may drive species composition at different spatial scales: at the largest scale, colonization of propagules may over-ride direct dispersal between pools, while at the scale of the single pool, differential movements of species give a nested structure to the meta-communities. The number of species increased as the level of analysis increased, even though this study was carried out along only a small stream section.