Green algae as a structural element of phytoperiphyton communities in streams of NW Russia

Observations were made on the development and distribution of phytoperiphyton communities in 66 lake-river systems in NW Russia from Lake Ladoga to the Barents Sea. In total, 130 genera and 648 species were identified from different substrates, belonging to Cyanophyta (19.1%), Bacillariophyta (59.6%), Chlorophyta (18.7%), and algae from other orders (2.6%). In all streams diatoms dominated by species richness, but they were surpassed by green algae in terms of biomass. The green algae ranged from small planktonic forms to large filamentous species and produced easily visible algal communities. Among the planktonic forms the desmids were the most diverse group. They occurred in attached communities of all rivers and, while never abundant, were widespread. The attached community’s biomass was dominated by green algae. Among these, the filamentous algae Mougeotia sp., Oedogonium sp., Zygnema sp., Spirogyra sp. and Ulothrix zonata exhibited mass development in streams. Their distribution was patchy in the basin, with a total cover varying from less than 1% to 90% of the stream bottom. In some river stretches the diversity and predominance of green algae could be due, in part, to poorly developed riparian canopies. The term periphyton adopted here follows the definition of Odum (1971): “Assemblages which include both plant and animal organisms growing attached to submerged objects”. The prefix phyto- is added to indicate that of the whole biocoenoses only phototrophs are considered in this study. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

THE SEASONAL DISTRIBUTION,ABUNDANCE AND DIVERSITY OF DESMIDS (CHLOROPHYTA) IN A SOFTWATER,NORTH TEMPERATE STREAM1

Suspended and benthic algal communities from a mildly acidic, third-order Rhode Island stream were examined to determine the seasonal distribution, abundance and diversity of the lotic desmids. Within a one-year sampling period, 148 species and 202 subspecific taxa of desmids were identified, representing 23 genera. Species of Cosmarium and Closterium accounted for approximately 70% of the desmids present, and were the most diverse and abundant taxa during all seasons except spring, when Hyalotheca dissiliens was the dominant desmid species. Average abundance and species richness generally were greatest during summer for both suspended and benthic desmids. Most desmids occurred in benthic habitats, and were randomly distributed among substrata. Average seasonal abundance was 7.4 × 10⁴ cells·g^?1 dry wt substratum, among 13 types of substrata. Highest desmid abundance was measured among substrata with intricate morphologies, such as Fontinalis spp., which was associated with 1.2 × 10⁶ desmid cells·g^?1 dry wt substratum, or 1.7 × 10³ cells·cm^?2 substratum. Cell division was observed for 70 desmid taxa, and average seasonal reproduction (based on cell numbers) among all substrata ranged from 4% in winter to 20% during summer. In addition, sexually produced zygospores were found occasionally for H. dissiliens. Desmids were distributed among most substrata examined in this stream, with abundance comparable to reported estimates from softwater lakes and acid bogs. In contrast to established dogma, lotic desmids are not incidental drift organisms, but rather comprise a viable and persistent component of the stream periphyton.     

Preface: New challenges in anostracan research,a tribute to Graziella Mura

Although conjugating algae are considered to have a cosmopolitan freshwater distribution, numerous ecological and taxonomic investigations revealed that many desmid taxa (at the level of genus, species and variety) are capable of occupying specific geographic zones, characterized by particular climatic attributes. Earlier studies have dealt with influences of temperature and irradiation (photosynthetically active radiation and ultraviolet radiation) on the physiology and ultrastructure of desmids. Yet, recent investigations demonstrated a clear relationship between these climatic factors and the distributional potential of conjugating algae, taking into account their photosynthetic, physiological and ultrastructural adaptations which had been revealed during and after certain temperature and irradiation treatments. Despite the fact that desmids can be considered as high-light-adapted algae, various species- and strain-specific characteristics and adaptations appeared in accordance with the light intensities predominating at their source localities, as estimated by their photosynthetic performance (obtained from PAM fluorometry and oxygen evolution measurements), pigment composition and morpho-anatomical characteristics. Interestingly, the high-light adaptation of photosynthesis as well as the relatively high growth temperature optima for majority of the desmid species investigated may provide some support for Coesel’s hypothesis on the origin of desmids in the tropical zone.     

Diversity and ecology of desmids of peat bogs in the Jizerské hory Mts

The present study focuses on diversity and ecological preferences of desmids in peat bogs in the Jizerské hory Mts (Czech Republic). Altogether 76 desmid algae taxa have been recorded at 18 sites of the study area during our investigation in 2003–2006. Taxa Actinotaenium crassiusculum (De Bary) Teiling, Hyalotheca dissiliens var. tatrica Racib., Staurastrum avicula var. subarcuatum (Wolle) West & G. S. West, S. borgeanum Schmidle, S. simonyi var. semicirculare Coesel, Staurodesmus extensus var. isthmosus (Heimerl) Coesel, S. extensus var. vulgaris (Eichler & Racib.) Croasdale and S. spencerianus (Mask.) Teiling are new for the Czech Republic. In addition, several rare and remarkable taxa were also encountered. The species richness was relatively high in comparison to similar localities in the Czech Republic. Desmid distribution was influenced by pH and conductivity. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

世界自然遗产地陆生藻类物种多样性比较研究

藻类是真核生物进化、植物起源与进化、生物地理学研究的良好材料,研究藻类物种多样性对理解生命起源与早期进化,探明地球地质地貌演化有着非常重要的意义。以两世界自然遗产地施秉云台山白云岩喀斯特、赤水丹霞的陆生藻类为研究对象,通过G-F多样性指数、Jaccard相似性系数、Bray-Curtis矩阵比较分析了不同地质地貌的两世界自然遗产地陆生藻类的物种多样性及种组特征,结果如下：（1）两地陆生藻类丰富,均以蓝藻为优势,共有优势科为色球藻科Chroococcaceae、颤藻科Oscillatoriaceae,施秉云台山还具伪枝藻科Scytonemataceae、念珠藻科Nostocaceae优势,优势属为粘球藻属Gloeocapsa、色球藻属Chroococcus,赤水丹霞仅以粘球藻属Gloeocapsa为优势。（2）施秉云台山G-F多样性指数高于赤水丹霞。（3）两地陆生藻类泛热带成分明显,施秉云台山中国特有成分较赤水丹霞丰富;两地科、属、种相似性系数依次为：56.25%、44.05%、37.62%,科的相似性达到中度水平,与同纬度范围其它地区的Bray-Curtis矩阵聚类结果显示不同地质地貌的两地首先聚为一类。从陆生藻类多样性组成上,初步反映两世界自然遗产地的地质历史、地层岩性及地理位置的异同。     

Investigating seed bank potential of crustose coralline algae using DNA metabarcoding

To examine the potential for the autogenic ecosystem engineers, crustose coralline algae (CCA), to serve as seed banks or refugia for life stages of other species, it is critical to develop sampling protocols that reflect the diversity of life present. In this pilot study on two shallow water species of CCA collected from Raoul Island (Kermadec Islands; Rangitāhua) New Zealand, we investigated two preservation methods (ethanol vs. silica gel), sampled inner and outer regions of the crusts, and used DNA metabarcoding and seven genes/gene regions (16S rRNA, 18S rRNA, 23S rRNA, cox1, rbcL, and tufA genes and the ITS rRNA region) to develop a protocol for taxa identification. The results revealed immense diversity, with typically more taxa identified within the inner layers than the outer layers. As highlighted in other metabarcoding studies and in earlier work on rhodoliths (nodose coralline algae), reference databases are incomplete, and to some extent, the use of multiple markers mitigates this issue. Specifically, the 23S rRNA and rbcL genes are currently more suitable for identifying algae, while the cox1 gene fares better at capturing the diversity present inclusive of algae. Further investigation of these autogenic ecosystem engineers that likely act as marine seed banks is needed.     

Intertidal meiofaunal biodiversity with respect to different algal habitats: a test using phytal ostracodes from Southern California

Rocky intertidal algae harbor a diverse invertebrate meiofauna of arthropods, nematodes and other invertebrates. Despite its ecological importance, relatively little is known about the diversity and composition of this important component of intertidal biodiversity. In this study, we quantified species composition, abundance and distribution of ostracodes, an important group of phytal meiofauna, at two different intertidal areas in southern California. In total, we recovered 22 ostracode species from three different orders (16 podocopids, five myodocopids and one platycopid), nearly a quarter of which could not be assigned to existing taxa. The abundance of ostracodes differed significantly among algal types, with structurally complex algae bearing many more ostracodes per gram of algae than simple forms (blade-like algae and the surfgrass Phyllospadix). Although most ostracode species were recovered from multiple kinds of algae, different algae harbored distinct assemblages that could be discriminated statistically on the basis of relative abundances of ostracode species. This segregation of the ostracode fauna according to algal species is evident even over very short spatial scales (<1 m). Finally, ostracode samples from turf-forming algae were more species rich than samples from other kinds of macroalgae. Since turf-forming algae are easily damaged by human trampling, this component of ostracode biodiversity may be particularly vulnerable to anthropogenic impacts on the intertidal habitat. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: K. Martens     

兰州五泉山的藻类及其分布

以兰州五泉山为该地藻种资源库,对其中水生、陆生生境中藻类的种类多样性、群落结构、分布特点进行了研究。结果发现该地藻类植物65种(含4变种),包括蓝藻、绿藻、硅藻和红藻,其中硅藻种类最多(29种),其它依次为蓝藻(24种)、绿藻(11种)和红藻(1种)。水体中共42种,硅藻最多,有26种,其次蓝藻8种,绿藻7种,红藻1种,不同水体中优势种和亚优势种不同。土壤生境中发现20种,蓝藻13种,绿藻4种,硅藻3种,且非洲席藻和小球藻分为优势种和亚优势种。7个种类在水、陆两大生境都有分布,而且它们主要是丝状蓝藻。     

Desmids of the Basrah District,South Iraq

79 taxa of desmids belongig to 17 genera were observed in 17 samples collected from several parts in Basrah district, South Iraq. 3 genera viz. Actinotaenium, Docidium and Spondylosum, and 41 taxa are new records for Iraqi waters. Distribution of taxa in the area studied as well as in the whole country (when available) are given. Some slight morphological variations in desmids were observed due to the alkaline nature of water.     

Upslope movements and large scale expansions: the taxonomy and biogeography of the Coenonympha arcania –C. d arwiniana –C. gardetta butterfly species complex

Sibling species groups are suitable models for the understanding of inter‐ and intraspecific processes in taxonomy and biogeography. We analysed 262 individuals from the Alps of the Coenonympha arcania/gardetta species complex by allozyme electrophoresis. These taxa showed high variance amongst populations (F_ST: 0.391) and strong intertaxon genetic differentiation (F_CT: 0.376). Although morphologically similar, Coenonympha gardetta and Coenonympha arcania clearly differ in their genetic characteristics; the morphologically intermediate taxa Coenonympha darwiniana darwiniana and Coenonympha darwiniana macromma are genetically well distinguished from each other and the two other taxa. Coenonympha arcania and C. d. macromma most probably share a common ancestor and evolved by cladogenesis, whereas the taxonomic situation of C. d. darwiniana is still unresolved: This taxon might be the result of hybridization between C. arcania and C. gardetta or it might have a common ancestor together with C. gardetta. We suggest species rank for all four taxa. The distribution of genetic diversity of these populations and the differentiation amongst populations suggest rather different biogeographical scenarios: C. arcania most probably is of Mediterranean origin with postglacial range expansion northwards; C. gardetta survived the last ice age in peripheral refugia of the Alps and has spread all over this high mountain system in the postglacial; C. darwiniana and C. macromma survived the Würm in geographic proximity to their actual distribution areas and only have performed moderate uphill translocations during postglacial warming. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 890–904.     

Putting incertae sedis taxa in their place: a proposal for ten new families and three new genera in Sphaeropleales (Chlorophyceae,Chlorophyta)

Best known for aquatic colonial algae such as Hydrodictyon, Pediastrum, or Scenedesmus, the order Sphaeropleales also contains numerous coccoid taxa from aquatic and terrestrial habitats. Recent findings indicate that coccoid lineages in this order are very diverse genetically and may be the prevalent form, although their diversity is often hidden morphologically. This study characterizes coccoid algae recently discovered from desert soil crusts that share morphological and ecological features with the genera Bracteacoccus, Pseudomuriella, and Chromochloris. Analyses of a multi‐gene data set that includes members from all sphaeroplealean families are used to examine the monophyly of these morphologically similar taxa, which are shown instead to be phylogenetically distinct and very divergent. We propose new generic names for these lineages: Bracteamorpha, Rotundella, and Tumidella. In addition, we propose an updated family‐level taxonomy within Sphaeropleales that includes ten new families of coccoid algae to accommodate the newly presented genera and many incertae sedis taxa in the order: Bracteamorphaceae, Chromochloridaceae, Dictyococcaceae, Dictyochloridaceae, Mychonastaceae, Pseudomuriellaceae, Rotundellaceae, Schizochlamydaceae, Schroederiaceae, and Tumidellaceae.     

4. Geographic distribution of freshwater blue-green algae

The analysis of the currently available data for morphologically unambiguously defined freshwater blue-green algae indicates that besides (sub-)cosmopolitan species, taxa with a more restricted distribution also exist. Many of these have a holarctic or pantropic distribution. It is hypothesized that, besides the distribution of ecological niches, temperature is one of the main controlling factors restricting species to particular latitudinal zones. Furthermore, the presence of species with a regional distribution (endemics) can not be ruled out, indicating that other factors must be considered. The possible role of dispersal capacities and of dispersal rates in relation to the earth history and to the speciation of blue-green algae is discussed.     

Desmids from ephemeral pools and aerophytic habitats from the Czech Republic

The distribution and ecology of desmids in wetland habitats in the Czech Republic were studied during 2003–2007. Samples were taken also from various aerophytic habitats and temporary pools thet had not been sufficiently studied before. Altogether 110 desmids taxa were found in 31 samples which were ordinated on the basis of their desmid species composition using a multivariate statistic method. The discussion focuses on the most interesting findings and on the factors that influence the distribution of desmids in different types of aerophytic habitats. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

A novel,combined approach to assessing species delimitation and biogeography within the well-known desmid species <Emphasis Type="Italic">Micrasterias fimbriata</Emphasis> and <Emphasis Type="Italic">M. rotata</Emphasis> (Desmidiales,Steptophyta)

Morphological species of freshwater microalgae often have broad geographic distribution. However, traditional species concepts have been challenged by the results of molecular phylogenetic analyses that mostly indicate higher diversity than was previously recognized by purely morphological approaches. A degree of phenotypic differentiation or different geographic distribution of species defined by molecular data remains largely unknown. In this study, we analyzed a pair of well-known and widely distributed desmid species (Micrasterias fimbriata and M. rotata) and tested for their phylogenetic and morphological homogeneity as well as their geographic distribution. Geometric morphometric and morphological attributes of cells were used in combination with genetic analysis of the trnG ^ucc sequences of 30 strains isolated from a variety of European locations and obtained from culture collections. Micrasterias rotata proved to be phylogenetically homogenous across Europe while M. fimbriata turned out to be composed of two firmly delimited lineages, differing by molecular as well as by morphometric and morphological data. Published records of traditional M. fimbriata were also included in the classification discrimination analysis and were placed into the newly identified lineages upon comparison to the morphometric data collected from living material. Largely disparate geographic patterns were revealed within traditional M. fimbriata. One phylogenetic lineage is frequent in central and eastern Europe, but occurs also in the British Isles. A second lineage has been recorded in North America and in Western Europe, where its distribution is possibly limited to the west of the Rhine River. Interestingly, the morphometric analyses of the published records illustrated that the geographic differences have remained largely unchanged since the 1850s indicating a previously unknown distributional stability among microalgal species groups such as the desmids.     

Flow cytometry sorting of freshwater phytoplankton

We used the flow sorting capacities of a benchtop FACSCalibur flow cytometer to analyze the phytoplankton community of four different aquatic ecosystems. We show that despite the high optical, mechanistic, and hydrodynamic stress for the cells while sorted, most of the targeted populations could be isolated and grew in mixed culture media subsequent to sorting. Forty-five phytoplankton taxa were isolated, including green algae (29 species), cyanobacteria (eight), diatoms (seven), and cryptomonads (one). The isolation success average was high since 80% of the total sorted populations grew successfully and 47% constituted monocultures. It is noteworthy, however, that some groups could not be isolated, as for example colonial cyanobacteria, chrysophytes, euglenophytes, desmids, or dinoflagellates, and some species such as Cryptomonas sp. were very sensitive to the sorting process. It is proposed that flow cytometric analysis of freshwater phytoplankton might be a relevant tool for water managers and could be applied in some specific cases, such as early monitoring of blooming taxa or basic bio-monitorings of key species. The higher isolation average obtained from the flow sorting can also be powerful for the physiological or molecular study of some taxa after their cultivation.     

5. Biogeography of desmids

Compared with other groups of unicellular freshwater algae, desmids lend themselves well to biogeographical studies since, at species level, identification is often relatively easy, whereas high ecological demands use to curtain their geographical distribution. Considering some ten desmid floral regions as distinguished in the beginning of this century, Indo-Malaysia/Northern Australia, tropical America, and equatorial Africa come to the fore as most pronounced. Also well typified are Eastern Asia, New Zealand/Southern Australia, and North America. Less endemic species are met with in Southern Africa and extratropical South America, whereas temperate Eurasia, with respect to the other continents, is mainly negatively characterized. The so-called arctic-alpine desmid flora may be encountered on all continents, provided that adequate minimum temperatures occur. Its distribution seems to be determined microclimatologically rather than macroclimatologically. Arguments for a tropical origin of the desmids as an algal group are adduced.     

Genetic diversity,distributional barriers and rafting continents — more thoughts on the evolution of mangroves

Without continental drift, the diversity and distribution of many species, including mangrove plants, would be very different today. First, there would be fewer pantropic genera and many more endemics. Second, their characteristics would not be as common and widespread as some are today. Continental drift has brought about the massive mixing and dispersal of genes in geologically recent times, greatly enhancing the evolutionary process; particularly for flowering plants — the angiosperms, which evolved during the period.Mangrove plants are comprised of approximately 70 species from 20 quite different angiosperm families. Most taxa are characterized by special physiological abilities and structural forms, enabling them to live in both seasonally fluctuating saline conditions, and water-saturated soils. Their occurrence is mostly tropical, perhaps because of harsh physiological conditions of intertidal habitats; but distributions of specific taxa do not fully concur with the idea of a completely tropical evolution, at least for some important species.At least one genus of mangrove tree, Avicennia, occurs around the world, chiefly in tropical estuarine habitats, although they also range into temperate latitudes, especially in the south. Around the world, there are no more than ten species of Avicennia recognised today, but their diagnostic determinants were inadequate prior to recent studies using both numerical analyses of morphological parameters and isozymes. Such analyses significantly reduced the number of apparent species, notably around Australia, and provided a basis for the revision of distributional records throughout the Indo West Pacific region. One species, A. marina, was found to be widespread and morphologically variable with genes divided into characteristic groupings of at least three geographic areas in the region. Based on these findings, there are several novel inferences to be made regarding the evolution of this genus. A western Gondwanan origin is proposed, with subsequent radiation of several taxa facilitated via the tectonic dispersal of southern continental fragments.     

Different speciation for bromine in brown and red algae,revealed by in vivo X‐ray absorption spectroscopic studies

Members of various algal lineages are known to be strong producers of atmospherically relevant halogen emissions, that is a consequence of their capability to store and metabolize halogens. This study uses a noninvasive, synchrotron‐based technique, X‐ray absorption spectroscopy, for addressing in vivo bromine speciation in the brown algae Ectocarpus siliculosus, Ascophyllum nodosum, and Fucus serratus, the red algae Gracilaria dura, G. gracilis, Chondrus crispus, Osmundea pinnatifida, Asparagopsis armata, Polysiphonia elongata, and Corallina officinalis, the diatom Thalassiosira rotula, the dinoflagellate Lingulodinium polyedrum and a natural phytoplankton sample. The results highlight a diversity of fundamentally different bromine storage modes: while most of the stramenopile representatives and the dinoflagellate store mostly bromide, there is evidence for Br incorporated in nonaromatic hydrocarbons in Thalassiosira. Red algae operate various organic bromine stores – including a possible precursor (by the haloform reaction) for bromoform in Asparagopsis and aromatically bound Br in Polysiphonia and Corallina. Large fractions of the bromine in the red algae G. dura and C. crispus and the brown alga F. serratus are present as Br^? defects in solid KCl, similar to what was reported earlier for Laminaria parts. These results are discussed according to different defensive strategies that are used within algal taxa to cope with biotic or abiotic stresses.     

Some algae from the Red Sea Hills in north-eastern Sudan

The algae contained in some plankton samples from several localities on four wadi in N.E. Sudan were examined. The observed algae amount to 260 taxa, of which the diatoms, representing 50% of the algal flora, are the most numerous. Other large groups are the blue-green algae (17%) and the green algae (24%) among which the desmids (6%) are rather unimportant.     

Evidence for sexual isolation as a prezygotic barrier to gene flow between morphologically divergent species of Rhagoletis fruit flies

1. Certain groups of fruit flies in the genus Rhagoletis (Diptera: Tephritidae) are exemplars for sympatric speciation via host plant shifting. Flies in these species groups are morphologically similar and overlap in their geographic ranges, yet attack different, non‐overlapping sets of host plants. Ecological adaptations related to differences in host choice and preference have been shown to be important prezygotic barriers to gene flow between these taxa, as Rhagoletis flies mate on or near the fruit of their respective host plants. Non‐host‐related assortative mating is generally absent or present at low levels between these sympatrically diverging fly populations. 2. However, some Rhagoletis taxa occasionally migrate to ‘non‐natal’ plants that are the primary hosts of other, morphologically differentiated fly species in the genus. These observations raise the question of whether sexual isolation may reduce courtship and copulation between morphologically divergent species of Rhagoletis flies, contributing to their prezygotic isolation along with host‐specific mating. 3. Using reciprocal multiple‐choice mating trials, we measured sexual isolation among nine species pairs of morphologically differentiated Rhagoletis flies. Complete sexual isolation was observed in eight of the nine comparisons, while partial sexual isolation was observed in the remaining comparison. 4. We conclude that sexual isolation can be an effective prezygotic barrier to gene flow contributing to substantial reproductive isolation between many morphologically distinct Rhagoletis species, even in the absence of differential host plant choice and host‐associated mating.