长江口附近海域春季浮游硅藻的种类组成和生态分布

2002年春季,在长江口附近海域典型赤潮高发区28个大面站位采集了53个样品,从中共鉴定出隶属于31个硅藻属的80个种和变种;其中种类多样性较高的属为圆筛藻属(Coscinodiscus),有17个种,斜纹藻属(Pleurosigma),有8个种和变种;数量上较优势的种为柔弱拟菱形藻(pseudo-nitzschia delicatissma),为3．48×10^3cells·L-1,占28．54％;具槽直链藻(Melosira sulcata),为1．43×10^3cells·L-1,占16．98％;尖刺拟菱形藻(Pseudo-nitzschia pungens),为0．71×10^3cells·L-1,占9．85％．它们在大部分站位中都有出现;柔弱拟菱形藻和尖刺拟菱形藻的高细胞密度区主要出现在1230E断面的站位,而具槽直链藻则主要出现在长江口的31～32°N断面的站位．浮游硅藻总细胞丰度变化于0．43×10^3～23．3×10^3cells·L-1,平均4．61×10^3cells·L-1;在123°E、30．5°N的DDl5站位,无论表层还是中层,浮游硅藻总细胞丰度均最高(表层,1．85×10^4cells·L-1;中层,2．33×10^4cells·L-1)．从水平分布看,浮游硅藻呈不均匀分布态势,从垂直分布看,大部分站位的表层浮游硅藻丰度高于中层．     

Influence of small-scale gold mining on French Guiana streams: Are diatom assemblages valid disturbance sensors?

The ongoing gold-rush in French Guiana could cause severe disturbance to ecosystems. Although illegal, small gold mining sites are rapidly expanding. Few studies have attempted to measure the consequences of the increased gold mining on the biota of small forest streams, and to date no study has dealt with primary producers. Here we measured the response of diatom assemblages to gold mining in ten sites differently affected by the mining activity (i.e., reference, formerly gold-mined and currently exploited). Our results showed that both taxonomic and functional structure of the diatom assemblages were influenced by the intensity of gold mining activity. A significant relationship between soil erosion and diatom motility ability has been demonstrated. These findings show that diatom assemblages are sensitive to gold mining disturbance and suggest that diatom communities may be used as sensors of the environmental stress caused by small-scale gold mining activities.     

兴凯湖湿地中国新记录硅藻

正兴凯湖是黑龙江流域最大的湖泊,由大、小两湖组成,均为造山运动地壳陷落而形成的构造湖。位于黑龙江省东南部,黑龙江垦区的兴凯湖农场和八五一零农场区域,距密山市35 km。大兴凯湖,北部三分之一面积属中国,南部属俄罗斯,是中俄界湖(中国境内,45°04′–45°31′N,132°01′–132°52′E)。小兴凯湖全部位于中国境内,东西长约36 km,南北宽约4.5 km~([1])。兴凯湖流域属寒温带大陆季风气候,湿地湖泊河流众多,藻类资源丰富~([2])。最早对该区域进行硅藻分类学研究的人是俄罗斯硅藻学家Skvortzow和德国硅藻学家     

光质对中华盒形藻生长及生化组成的影响

中华盒形藻的增殖率在白光下最大,蓝光下次之,红光下最小。叶绿素、蛋白质的合成明显受蓝光促进,而红光下碳经合物含量增加。脂类含量在蓝光、红光下均有所下降。     

Species temporal variability: epigaeic ant assemblages and management for abundance and scarcity

Summary Ant assemblages in five closely-spaced point habitats were studied over a three-year period in a subtropical area of South Africa. A total of 20,746 individuals in 56 species were sampled with pitfall traps. Rapid species turnover occurred during short periods after longer intervals of relatively constant species composition. There was annual cycling of total numbers of individuals. The temporal variance for total number of individuals within each habitat increased significantly with mean population size by a logarithmic regression. This indicates that population fluctuations are dependent upon the mean, with a distinctive relationship. The total number of species was cyclical, with annual and approximately half-yearly cycles. Each habitat nevertheless carried a characteristic mean number of species. The temporal variance of species richness showed a highly significant positive logarithmic relationship with the mean number of species. Pheidole megacephala (F.) accounted for 45% of all individuals. Its overall population showed annual cycles. Ph. megacephala population trend was the main determinant for seasonal variation of the whole assemblage in most habitats. Percentage dominance was positively linearly correlated with the variance and with mean population level. Although Ph. megacephala population variance increased with the mean, proportionate variability did not, indicating that high populations are no more variable than low populations. Five variability measures were compared with each other on ant assemblages containing only the common species (1st quartile) and then including the increasingly rare species (1st and 2nd, 1st, 2nd and 3rd, and all quartiles). Williamson's Variability Measure, using logarithmic or inverse sine transformations, gave variable results depending whether or not the rarer species were included in the analysis. The Coefficient of Fluctuation also gave variable results depending on assemblage size. The Coefficient of Variation and Proportionate Variability Measure gave similar and consistent results, indicating that common species are not more variable than rare ones. The rarer species are stenotopic and tend always to be rare, whereas the common species are eurytopic, highly competitive and demographically volatile. Control measures for common ants, and conservation of rare ants, should take cognizance of these trends.     

湿地生态系统设计的一些基本问题探讨

湿地生态系统设计是恢复、调整湿地的重要手段,本文3从湿地生态系统设计概念入手,阐述了设计的基本原则。较详细地讨论了设计中的指标（水文指标、化学指标、基质指标和生物指标）要求,根据湿地生态系统设计的用途不同,探讨了3种主要的湿地生态系统设计类型,即作为废水处理湿地的设计,作为调整湿地的系统设计和作为洪水及非点源污染控制的湿地设计。     

Changes in coral reef communities among the Florida Keys, 1996–2003

Hard coral (Scleractinia and Milleporina) cover data were examined from 37 sites surveyed annually from 1996 to 2003 in the Florida reef tract, USA. Analyses of species numbers and total cover showed that site-to-site differences were generally very much greater than differences among times within sites. There were no significant differences among different geographical areas within the reef tract (Upper, Middle and Lower Keys). Large-scale changes documented included a reduction in species numbers and total cover on both deep and shallow offshore reefs between 1997 and 1999 followed by no recovery in cover, and only scant evidence of any recovery in species numbers by 2003. These changes coincided with bleaching events in 1997 and 1998, and the passage of Hurricane Georges through the Lower Keys in 1998. The lack of recovery among offshore reefs suggests that they were no longer resilient. Multivariate analyses revealed that some sites showed relatively little temporal variation in community composition, essentially random in direction, while others showed relatively large year-on-year changes. There was little evidence of any major region-wide changes affecting assemblage composition, or of any events that had impacted all of the sampling sites in any single year. Instead, different sites exhibited differing patterns of temporal variation, with certain sites displaying greater variation than others. Changes in community composition at some sites are interpreted in the light of knowledge of events at those sites and the relative sensitivities of species to various stressors, such as changes in cover of Acropora palmata and Millepora complanata at Sand Key following the bleaching events and hurricane in 1998, and declines in Montastraea annularis at Smith Shoal following a harmful algal bloom in 2002. For most sites, however, it is impossible to determine the causes of observed variation.     

Allium ampeloprasum var. babingtonii (Alliaceae): an isoclonal plant found across a range of habitats in S.W. England

Despite the widespread distribution and common habitat dominance of clonal plant species the mechanisms for their ecological success often remain uncertain. Allium ampeloprasum var. babingtonii is a sterile plant that reproduces with physiologically independent asexual propagules. The variety is found mainly in the S.W. of England over a wide habitat range including sea cliffs and open woodlands and displays an autumn-spring phenology in common with its close Mediterranean relatives. The role of population genetic structure in the remarkable habitat distribution of the variety is not known. Genetic variation in A. ampeloprasum var. babingtonii was analysed using RAPD markers in single individuals of var. babingtonii from 16 distinct populations and five further individuals from a single population. This analysis revealed no polymorphism suggesting that all sampled individuals are part of a single clone. We offer the conjecture that in the absence of genetic variation an ecological release, due to temporal separation from competing species, may contribute to the ability of var. babingtonii to exploit heterogeneous environmental conditions.     

Effects of temporal variability of disturbance on the succession in marine fouling communities in northern-central Chile

We investigated the effects of temporal variability in a disturbance regime on fouling communities at two study sites in a northern-central Chilean bay. Fouling assemblages grown on artificial settlement substrata were disturbed by mechanical removal of biomass at different time intervals. Using one single disturbance frequency (10 disturbance events over 5 months) we applied 7 different temporal disturbance treatments: a constant disturbance regime (identical intervals between disturbance events), and 6 variable treatments where both variableness and sequences of intervals between disturbance events were manipulated. Two levels of temporal variableness (low and high, i.e. disturbance events were either dispersed or highly clumped in time) in the disturbance regime were applied by modifying the time intervals between subsequent disturbance events. To investigate the temporal coupling between disturbance events and other ecological processes (e.g. larval supply and recruitment intensity), three different sequences of disturbance intervals were nested in each of the two levels of temporal variableness. Species richness, evenness, total abundance, and structure of communities that experienced the various disturbance regimes were compared at the end of the experiment (15 days after the last disturbance event). Disturbance strongly influenced the community structure and led to a decrease in evenness and total abundance but not species richness. In undisturbed reference communities, the dominant competitor Pyura chilensis (Tunicata) occupied most available space while this species was suppressed in all disturbed treatments. Surprisingly, neither temporal variableness in the disturbance regime nor the sequence of intervals between disturbance events had an effect on community structure. Temporal variability in high disturbance regimes may be of minor importance for fouling communities, because they are dominated by opportunistic species that are adapted to rapidly exploit available space.     

Validation of ecological status concepts in UK rivers using historic diatom samples

We assessed the feasibility of using herbarium specimens to validate reference conditions in the UK by comparing diatom community composition of river sites with both recent and historic diatom samples. The question of substrate specificity was addressed by comparing epilithon (stone-derived) and epiphyton (plant-derived) samples from a number of rivers. No significant differences were found between the Trophic Diatom Index (TDI), species richness, species diversity, and percentage of motile valves between paired diatom samples (epilithic and epiphytic) from contemporary samples. Significant differences were recorded between a number of indices derived from analysis of the historic diatom samples on plant material sampled pre-1930 compared with diatoms from stones collected post-1990 from the same river location. The TDI, mean species richness, and species diversity and percentage of motile valves and nutrient tolerant valves were all significantly greater in the contemporary samples (p ≤ 0.05). The percentage of nutrient sensitive valves was significantly lower in the contemporary samples (p ≤ 0.05).The relative abundance of Achnanthidium minutissimum and Cocconeis placentula var. lineata was significantly greater on the herbarium material compared to matched contemporary samples. Calculated values for the TDI (43 ± 3) expected at reference conditions were similar to the observed TDI values derived from herbarium material (44 ± 12) showing no significant deviation in ecological status.     

Effects of ungulates on epigeal arthropods in Sierra Nevada National Park (southeast Spain)

This paper examines the effect of ungulates on epigeal arthropod communities in two common plant communities of the high mountains of the Sierra Nevada (southeast Spain). We have compared the abundance, biomass, diversity and specific composition of arthropod communities in grazed and ungrazed plots experimentally excluded from ungulates. In general, we found that arthropods were more abundant and diverse in grazed than in ungrazed plots. However, the effect of ungulates depended on the variable considered (diversity versus abundance versus biomass). Moreover, ungulates also affected species composition. This means that without affecting diversity, ungulates can still have a strong effect on arthropod communities by changing species composition. Also, the relationship between ungulates and arthropods differed depending on the year of study and the sampling period. In conclusion, our study indicates that to extrapolate the results obtained for a group of insects, a habitat or a sampling period is not appropriate for the conservation of arthropod communities.     

Inter-annual plasticity of squid life history and population structure: ecological and management implications

Population size and structure, as well as individual growth rates, condition, and reproductive output, respond to environmental factors, particularly in short-lived and fast-growing squid species. We need to understand the mechanisms through which populations respond to environmental conditions, to predict when or if established relationships, used as management tools to forecast recruitment strength, might break down completely. Identifying characteristics of successful recruits who have grown under different environmental scenarios may improve our understanding of the mechanistic connections between environmental conditions and the temporal variation in life history characteristics that ultimately affect recruitment. This 5-year study sought to determine the association between key life history characteristics of southern calamary Sepioteuthis australis (growth rate, body size, and patterns of repro-somatic energy allocation) and the environmental conditions experienced by individuals on the east coast of Tasmania, Australia. Among years, all population and individual parameters examined were highly variable, despite the environmental regime during the study not encompassing the extremes that may occur in this dynamic region. Temperature was not clearly associated with any of the individual or population differences observed. Populations of apparently similar abundance were composed of individuals with strikingly different biological characteristics, therefore seeking relationships between abundance and environmental parameters at gross levels did not shed light on the mechanisms responsible for population size. Importantly, inter-annual differences in squid size, condition, reproductive investment, and possibly growth rate, were sex-specific, indicating that males and females responded differently to similar factors. Among years differences in body size were extreme, both among the male component of the population and between genders. The relative importance of many size-based processes that contribute to population size and structure (e.g. predation, starvation, competition, and reproductive success) will therefore vary inter-annually.An erratum to this article can be found at     

中国河口湿地研究现状及展望

河口湿地由于其发育和形成过程较为特殊,加上其丰富的动植物资源以及重要的经济地位,已成为我国湿地研究领域的一个新热点.本文在分析中国河口湿地分布与特征的基础上,从河口湿地生物多样性、河口湿地生态过程及动态变化、河口湿地的形成和发育机制、河口湿地景观格局及动态演变、河口湿地恢复与重建、河口湿地的人地关系、河口湿地与全球变化、河口湿地评价以及数字河口湿地建设等方面总结了我国河口湿地研究现状.尽管中国河口湿地研究的方向和成果已经比较丰富,但与国外相比,在技术和理念上还存在一定差距.结合国外河口湿地研究的最新动态,提出了中国河口湿地未来研究的4个重要方向：河口湿地的人地关系、河口湿地的恢复和重建、河口湿地与全球变化以及河口湿地综合信息系统建设.