中国淡水中心纲硅藻研究

本文仅报道属于中心纲硅藻的二新种和一新变种以及对菱形小环藻Cyclotella rhomboideo—elliptica Skuja(1937)特征的补充和修改。     

九寨沟长海中心纲硅藻的分类学研究及报道1个新种

研究报道了采自中国四川九寨沟自然保护区长海的4种中心类硅藻种类, 其中新种1个: 长海小环藻(Cyclotella changhai sp. nov.), 中国新记录种1个: 克里特小环藻(C. cretica)和2种较少报道的种类: 可辨小环藻(C. distinguenda)和辐纹琳达藻(Lindavia radiosa)。通过光学显微镜和扫描电子显微镜对这4个种类形态学的特征进行观察, 并与相似种类进行比较。与长海小环藻相似的种类包括C. comensis Grunow, C. pseudocomensis Scheffler和C. costei Druart & Straub, 主要通过壳面中央区的不同形态进行区分-长海小环藻的中央区近平滑且具有不规则的凹陷。     

中国淡水中心纲硅藻研究

本文仅报道属于中心纲硅藻的二新种和一新变种以及对菱形小环藻Cyclotella rhomboideo-elliptica Skuja(1937)特征的补充和修改。 1.罗兹直链藻西藏变种 (新变种) Melosira roeseana var.xizangensis     

福建金门岛的淡水硅藻初报

报道了2004年11月采自福建省金门岛的淡水硅藻共126个分类单位,包括81种40变种5变型,隶属于2纲6目11科26属,其中瓦尔斯布纹藻Gyrosigma wansbeckii(Donk in)C l.、华美舟形藻Navicula elegansW.Sm ith、扁羽纹藻Pinnularia fasciata(Lagerst.)Hust.、近缘桥弯藻埃法变种Cym bella affinisvar.afarensisGasse、澳大利亚桥弯藻Cym bella australica(A.Schm idt)C leve、多西诺桥弯藻Cym bella dorsenotata strup、近极菱形藻Nitzschia polarisG run.、近粘连菱形藻斯科舍变种Nitzschia subcohaerensvar.scotica(G run.)Van Heurck、具脐菱形藻Nitzschia um bili-cataHust.为中国新纪录。     

硅藻分子生物学研究的一些进展

介绍分子生物学技术在硅藻基因组结构、基因克隆与定序、基因定位与遗传图谱构建、基因表达与调控以及系统发生学等方面的研究中取得的一些进展。     

海南岛淡水单壳缝类硅藻的分类学研究

对采自海南岛的淡水硅藻进行了分类学研究,共观察到曲壳类硅藻40个分类单位。其中11个分类单位为中国新记录,分别为岛曲壳藻Achnanthes islandica、阿奇长曲壳藻Achnanthidium archibaldianum、高尔夫长曲壳藻Achnanthidium caledonicum、弯曲长曲壳藻Achnanthidium deflexum、河流长曲壳藻Achnanthidium rivulare、极常见平面藻Planothidium frequentissimum、皮亚夫平面藻Planothidium piaficum、短肋片状藻Platessa brevicostata、胡斯特片状藻Platessa hustedtii、山地片状藻热带变种Platessa montana var.tropica、扁圆卵形藻尖细变种Cocconeis placentula var.acuta。文章对这11个分类单位的形态特征及生境分布特点进行了描述,讨论了同相近种类的区别特征。对片状藻属Platessa的分类特征进行了中文描述。     

华山的硅藻

华山是我国名山之一。这里的植物以前很少有人研究,藻类方面,至今未见有人报道。1976年至1982年作者对该地区进行了多次调查采集,现将研究结果报道如下。     

光滑侧链藻——中国淡水硅藻新记录

2004-2006年,对武汉东湖的底栖藻类进行了生态学调查研究.在对底栖硅藻的定性和定量研究中,发现了一种中心纲种类为中国新记录,它具有一些海洋角盘藻科种类的特征,如眼纹斑(Ocellus)等.经鉴定为光滑侧链藻Pleurosira laevis(Ehrenberg)Compere.参考Compere 1982年的研究,我们同意他的看法,即以前在我国台湾发现的台湾多变筒藻Proteucylindrus taiwanensis Li et Chiang和广东发现的Cerataulus laevis var.?chinensis Grunow也应归于侧链藻属(Pleurosira),名称为索科特拉侧链藻Pleurosira socotrensis(Kitton)Compere.     

我国几种新记录的硅藻

本文报道了采自安徽的我国分布新记录的硅藻有3种及3变种。     

A METHOD FOR THE QUANTITATIVE AND QUALITATIVE DETERMINATION OF PLANKTONIC DIATOMS

SUMMARY

A method for the quantitative and qualitative determination of planktonic diatoms was developed. The method uses the Utermöhl counting technique (in which an inverted microscope is employed) as a basis but also involves the calculation of the relative density of each species in the association (as determined with the ordinary light microscope). A combination of the results thus obtained ensures that even the smallest diatoms (2,5 μm) are accounted for. These often constitute a significant proportion of the population, but are often overlooked or may not even be resolved using Utermöhl's method.     

Distribution of epipelic diatoms in artificial fishponds along environmental and spatial gradients

Although epipelic diatoms play a key role in primary production of many ecosystems, many aspects of their biodiversity, ecology and geographical distribution are poorly understood. The present study is based on sampling of 45 man-made fishponds in the Czech Republic covering an environmental gradient from oligo/dystrophic highland ponds within protected areas to the eutrophic/hypertrophic lowland ponds used for intensive fish production. Diatom distribution patterns assessed using biomass and species composition variables were assessed along environmental and geographical gradients. In total, 185 epipelic diatom taxa were found in the investigated samples. The differences in species composition between sites were correlated with environmental parameters, but not with the geographic distance of the localities. This pattern might suggest that niche-based control, rather than the effect of dispersal limitation, is the main driving force in the species composition of epipelic diatoms in fishponds. The alpha-diversity of sites correlated with altitude, nitrogen and chlorophyll a concentrations but did not correlate with the area of the ponds. The significant relationships between local abundance of species and their regional occupancy were very similar to previous studies of diatoms in boreal streams. In addition, these data concur with patterns known for multicellular organisms suggesting that in this respect diatoms may not differ from groups of organisms with larger body sizes. Handling editor: J. Padisak     

Is diatom size selection by harpacticoid copepods related to grazer body size?

Copepods are known as important consumers of primary production and are eaten by larger animals. They therefore form a main link to higher trophic levels. While feeding pathways and specificity of planktonic copepods have been well studied, the selectivity of the benthic harpacticoid copepods is far less documented. A better knowledge of the functional ecology of harpacticoids as important grazers on primary producers may have consequences for the re-evaluation of basic energy flow in benthic ecosystems.We tested whether size selectivity for diatoms exists in harpacticoid copepods. We hypothesized that size selectivity of harpacticoid copepod species is strongly related to body size. Because of morphological constraints, we expected smaller copepods to prefer smaller diatoms while larger copepods should be able to consume both small and large diatoms. We tested this hypothesis in four harpacticoid copepod species of varied body size: Tigriopus brevicornis, Harpacticus obscurus, Amphiascus minutus and Paramphiascella fulvofasciata. As food source we used two ¹³C labelled strains of the benthic diatom Seminavis robusta with a four-fold difference in cell biovolume.Three out of four harpacticoid species showed size selectivity: H. obscurus and A. minutus preferred the larger Seminavis cells, while P. fulvofasciata selected the smaller Seminavis cells. Based on monoclonal treatments, there was no clear preference found for T. brevicornis although there was a small preference for large cells in the mixed treatments. Except for P. fulvofasciata, all species showed a lower uptake when offered the mixed diet (both small and large cells). Although most species showed a size selectivity, our results suggest that this selectivity was not related to their body size. However, the only species that ate significantly more of small diatoms was characterised by comparatively small mouthparts in relation to its body size.     

Vertical migration rhythm in freshwater diatoms

Epipelic diatoms of a pond undergo a vertical migration rhythm moving to the surface of the sediment in the morning and downwards again in the afternoon.In the laboratory the same rhythmicity was found with a maximum of cells on the surface at noon or in the afternoon. Under the experimental conditions employed there was no evidence of two or more peaks.As in some, but not all, unicellular algae of the tidal zone, this migration shows the characteristics of endogenous circadian rhythms, such as persistance in continous light or dark and reversal of the phase by shift of 12 hours in the Zeitgeber: light.     

Biogeography and ecology of freshwater diatoms in Subantarctica: a review

Subantarctica is situated between the Antarctic and the Subtropical Convergence and consists of the islands in the southern Atlantic, Indian and Pacific Oceans. Diatoms are an important component of all Subantarctic aquatic, moss and soil habitats. Taxonomic studies reveal a high diversity and species richness in both the present-day and the fossil diatom flora. Planktonic diatoms are almost completely absent. A similarity analysis of the diatom composition from different localities in the southern zone (below 40°S) resulted in a biogeographical zonation. Three regions could be formed, based on their diatom composition: Subantarctica, Maritime Antarctica and the Antarctic Continent. The diatom communities in the different regions are all characterized by a high proportion of cosmopolitan species. A second feature of the southern diatom floras is the decreasing diversity when moving southwards.     

Diatom distribution in the Southern Adriatic Coastal waters

Abstract

Data on the horizontal and vertical distribution of diatom species, collected between April 1995 and March 1996 in coastal waters of the Apulian Adriatic Sea are presented. A total number of 120 species belonging to 51 genera were identified. Diatoms were dominant in the major part of the examined samples, constituting up to 90% of the total cell numbers during the spring period.     

Cytoplasmic free calcium in single cells of centric diatoms. The use of fura-2

Summary Cytoplasmic free calcium concentration has been measured in centric diatoms using Fura-2. Cells hydrolysed Fura-2 acetoxymethyl ester and accumulated free Fura-2 in the cytoplasm. The [Ca²⁺] distribution in two species (Coccinodiscus concinnus andGuinardia flaccida) has been mapped using digital image analysis.Abbreviations [Ca_cyt²⁺] Cytoplasmic free calcium concentration - Quin-2/AM Quin-2 acetoxymethyl ester - Fura-2/AM Fura-2 acetoxymethyl ester DMSO dimethyl sulphoxide - CCTV closed circuit television