Desmid Communities Research Articles

Spatial variation of periphytic desmid community structure on emergent macrophytes in a tropical urban watershed

Spatial variation of periphytic desmid community structure on emergent macrophytes in a tropical urban watershed

Taxonomy and ecology of Sphagnum-associated Desmids from the New England Tablelands, New South Wales, Australia

Desmids associated with Sphagnum L. from terrestrial and aquatic habitats were investigated in the New England Tableland Bioregion. Descriptions and figures for 80 taxa are presented herein, nine of which are newly recorded for Australia, and a further seven are newly recorded for New South Wales. Two novel species of desmid, Micrasterias bicoronata A.Kenins and Cosmarium phymatodeum A.Kenins, are described. The floristic composition of desmids at Basket Swamp and Ebor Common, were compared to assess their conservation value based on an existing and modified scheme better suited to desmids from Australia. Basket Swamp received a relatively high score based on greater species richness and numerous endemics present. In contrast, Ebor Common scored lower due to less diversity and few regionally endemic species. This study also highlights that the desmid community found amongst Sphagnum in Australia is highly diverse (βSOR = 0.82) and can differ markedly among the four assessed sites due to spatial turnover (βRATIO = 0.15). While there are species in common with the much more extensively studied Sphagnum habitats in central and western Europe, Australia has its own distinctive desmid floral elements.

Biomass distribution in desmid communities

Biomass distribution in desmid communities

Ecological and biogeographical drivers of freshwater green algae biodiversity: from local communities to large-scale species pools of desmids.

Dispersal limitation, niche-based processes as well as historical legacies shape microbial biodiversity, but their respective influences remain unknown for many groups of microbes. We analysed metacommunity structure and functional trait variation in 148 communities of desmids, freshwater green algae, distributed throughout Europe. We delineated biogeographic modules for both taxa and sites using bipartite network analysis given that the taxa of a module co-occurred more often than expected by chance in sites of the same module. The network analysis distinguished two main acidic and neutral habitats, reflecting environmental filtering, and within each habitat separated species pools with distinct geographic locations, representing a plausible influence of historical biogeography. The geographic differentiation was consistent with a hypothesis of glacial refugia on Atlantic coast. Distance decay in community composition in addition to environmental influence further suggested a role of dispersal limitation. Next, we quantified the variation in cell volume and surface-to-volume of taxa within and among communities, to examine morphological and physiological adaptations of desmids in varying environments. Communities from continental climate contained larger desmids. Conversely, we found a functional convergence of smaller, fast-growing, desmids in oceanic regions. Overall, our findings suggest that niche-based processes, dispersal limitation, and historical legacy together drive the distribution and structure of desmid communities. Combining trait- and network-based analyses can resolve long-lasting questions in microbial ecology and biogeography, and could be successfully used in macrobial ecology too.

Diversity and ecology of desmids of peat bogs in the Jeseníky Mts: spatial distribution, remarkable finds.

Diversity and ecology of desmids (Zygnematophyceae) were studied within eight peat bog sites in the Jeseniky Mts during the years 2006-2009. Altogether, 51 taxa were found in the course of our investigation. A detailed study of spatial distribution of desmids in relation to environmental characteristics was performed. The composition of desmid communities was influenced especially by water table elevation and pH. Among all chemical substances measured and statistically tested, Mg, Ca and Pb concentrations appeared to have a considerable effect. Several remarkable desmid taxa were found and discussed in terms of their occurrence and broad morphological variability.

The desmids of the Swamp Nature Reserve and a small neighbouring bog: species composition and ecological condition of both sites.

The present study is a summary of recent findings concerning the desmid flora of the Swamp Nature Reserve and a small neighbouring bog. A total of 203 desmid taxa belonging to 22 genera were found, including 39 taxa that are considered very rare in the Czech Republic. Of this number, 46 taxa were found in the Swamp and 203 taxa in the neighbouring bog. The ecological condition of both localities was assessed on the basis of the species composition of the desmid communities encountered. The results indicate that the present overall ecological situation of the Swamp is favourable for the development of a characteristic, acidophilous desmid community. They also document quite an exceptional natural value of the second site studied, fully justifying its recent designation as part of the Swamp Nature Reserve. The results presented here may also be used in the future as a basis for comparative ecological studies tracing the development of both these sites.

Some new and interesting ecological observations on desmids from the Province of Vojvodina (Northern Serbia)

A detailed qualitative investigation of the desmid community in the territory of the Province of Vojvodina (Northern Serbia, part of the Pannonian Plain) revealed a surprisingly high number of desmid taxa. Although most of the desmids were marked as rare, according to the results of physico-chemical analyses of water samples, several taxa were frequently recorded in habitats that are generally deemed unsuitable for desmids. The ecological characteristics of 18 desmid taxa, some of which known as acidophilic and/or oligotrophic, are briefly discussed. The unexpected presence of many desmid taxa is explained by assuming that their tolerance threshold to various physico-chemical parameters has changed considerably.

Desmid flora (Chlorophyta, Zygnematophyceae) of the Danube in the province of Vojvodina (Northern Serbia)

This paper presents results of a detailed investigation into the qualitative composition of the desmid flora of the Danube performed from April of 2002 to May of 2003. A total of 70 desmid taxa belonging to four genera were recorded. Forty-seven taxa are new to the Vojvodina stretch of the Danube, while Cosmarium kjellmanii, Staurastrum bloklandiae, and S. smithii are taxa new to the algal flora of Serbia. Qualitative dominance of desmid taxa typical of alkaline and eutrophic ecosystems was observed. The qualitative composition of planktonic taxa, their quantitative composition, and regular seasonal dynamics of the desmid community were analyzed in the relation to physico-chemical characteristics of the water. Water quality was analyzed on the basis of desmids, which are bioindicators. The partly unexpected presence of certain desmid taxa, i.e., several typical acidophilous species, alpine forms, and/or taxa characteristic of oligotrophic water was recorded.

Substrate specificity of periphytic desmids in shallow softwater lakes in Belgium

At 6 sites in 5 mesotrophic softwater lakes in the wetland Zwart Water (Belgium), periphyton samples were collected on different substrates ranging from macrophytes to mosses and sandy sediment. Significant differences between substrates were observed at 5 out of 6 sites studied. The differences between the substrates, however, could not be related to known effects of these substrates on their chemical environment (e.g., excretion of H+ ions, CO2 or allelopatic substances) nor to their morphology. Therefore, differences between substrates were probably related to differences in local environmental conditions associated with these substrates. Differences in desmid community composition between substrates within a lake were always smaller than differences with samples from other lakes.

Ecological remarks on the desmid communities from the Lower Uruguay River System (Argentina)

Ecological remarks on the desmid communities from the Lower Uruguay River System (Argentina)

Structural Characteristics and Adaptations of Desmid Communities

SUMMARY (1) Nearly 400 samples containing desmids, previously referred to three groups by the application of a classification program, were ordinated on the basis of their desmid species composition. (2) In alkaline, open water habitats, as eutrophication increased, there was a decrease in desmid diversity, and an increase in the proportion of planktonic forms. (3) Submerged fen-hollows were dominated, in relatively eutrophic sites, by small desmids with short generation times, whereas in relatively oligotrophic sites, larger desmids with longer generation times prevailed. The greatest desmid diversity occurred in the middle part of the trophic range; this is explained by a greater niche differentiation resulting from frequent fluctuations in nutrient concentrations in the habitat. (4) In emergent fen habitats, the desmid diversity decreased with decreasing moisture content and rising acidity. The relative contribution of omniradiate forms with a small surface: volume ratio increased. (5) The ecological significance of these characteristics, and the relationship between genera: species ratio and habitat are discussed.

Wisconsin desmids. III. Desmid community composition and distribution in relation to lake type and water chemistry

This investigation summarizes quantitative data on the generic composition of the euplankton and aufwuchs desmid communities of 61 Wisconsin lakes, and analyzes the information with respect to 1) the role of the various genera in terms of frequency, density, and relative importance, 2) the suitability of various lake types for harboring desmid communities, and 3) the relationships between chemical parameters and desmid distribution. The generaStaurastrum, Cosmarium, andClosterium are of wide occurrence, appear to play major roles in the communities of all lake types, and are the most tolerant of varying chemical conditions. Most euplankton genera are of importance only in acid bogs, but aufwuchs genera generally are more widely distributed. Both the euplankton and the aufwuchs communities appear to be composed of 1–4 desmid assemblages, each with a differing range of importance values. Based on biological criteria, acid bogs appear to be the most suitable lake type for harboring desmid communities and calcareous spring ponds the least suitable type. High generic diversity of desmids appears to be correlated with low conductivity, calcium and alkalinity levels, pH values of 5.1–7.0, and the presence of free CO2. The evidence attending various hypotheses concerning water chemistry and desmid distribution appears contradictory, and further studies are needed to help clarify the situation.

Wisconsin desmids. I. Aufwuchs and plankton communities of selected acid bogs, alkaline bogs, and closed bogs

Data are presented for 28 acid bogs, five alkaline bogs, and 12 closed bogs in Wisconsin with respect to the summer composition of the aufwuchs and plankton ccommunities, the relative importance of desmids in these communities, and the structure of aufwuchs communities associated with different macrophyte hosts. Generic diversity of desmids is highest in acid bogs and lowest in alkaline bogs and generally is greater in the aufwuchs community than in the plankton community at a given site. Whenever it was present, the greatest diversity occurred in association with the macrophyte host Utricularia. Among lakes of a given type, relationships between the occurrence of desmid genera and parameters of the chemical environment were not apparent for either the aufwuchs or plankton communities. Similarly, no clear-cut distinctions occur in the desmid communities of the three lake types in terms of population densities and percentage contribution to the total population, but acid bogs tend to have a somewhat more prominent flora quantitatively. Statistically significant differences in desmid population densities from one host to another within a given lake did occur in lakes of all three types, and this suggests that the nature of the substrate can definitely influence community size and composition. Data for other algal groups are similarly treated, and brief comparisons of the mat and open water communities of alkaline bogs are included.