The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Kevin Murphy - One of the best experts on this subject based on the ideXlab platform.
-
invertebrate hydraulic microhabitat and community structure in Callitriche stagnalis scop patches
Hydrobiologia, 1999Co-Authors: Matthew T. Ó. Hare, Kevin MurphyAbstract:In this paper, we report the structure of the benthic invertebrate community in submerged Callitriche stagnalis Scop. stands in relation to velocity, in a Scottish river, the Blane Water. We compared the community within the macrophyte beds to that of adjacent unvegetated substrate. Callitriche stagnalis stands supported different taxa richness (no. of taxa) and abundances (no. of individuals) of benthic invertebrates than the unvegetated riffle substrate (Wilcoxon Matched-Pairs test: p<0.01, n = 10). To see if different sections of the stands supported different invertebrate communities, samples were taken from the outer, mid and root sections of the stands. The sections were separated by Detrended Correspondence Analysis (DCA) using their macroinvertebrate communities (eigenvalues: axis 1 = 0.6, axis 2 = 0.136). Abundance and taxa richness were different between the outer and mid sections, and between outer and root sections (Wilcoxon Matched-Pairs test: respectively p<0.05, p<0.01, n = 10). Community structure also differed between sections. The outer section community had a structure similar to that of an extreme environment where Simuliidae were dominant. Ephemerella ignita dominated in the mid and root sections. Differing combinations of plant structure and velocity appear to be a major factor influencing habitat structure, creating a range of stability conditions in the stands, which support the observed diversity of invertebrate assemblages present.
-
Invertebrate hydraulic microhabitat and community structure in Callitriche stagnalis Scop. patches
Biology Ecology and Management of Aquatic Plants, 1999Co-Authors: Matthew T. Ó. Hare, Kevin MurphyAbstract:In this paper, we report the structure of the benthic invertebrate community in submerged Callitriche stagnalis Scop. stands in relation to velocity, in a Scottish river, the Blane Water. We compared the community within the macrophyte beds to that of adjacent unvegetated substrate. Callitriche stagnalis stands supported different taxa richness (no. of taxa) and abundances (no. of individuals) of benthic invertebrates than the unvegetated riffle substrate (Wilcoxon Matched-Pairs test: p
Vlasta Jarolimova - One of the best experts on this subject based on the ideXlab platform.
-
genome size as a key to evolutionary complex aquatic plants polyploidy and hybridization in Callitriche plantaginaceae
PLOS ONE, 2014Co-Authors: Jan Prancl, Zdeněk Kaplan, P Travnicek, Vlasta JarolimovaAbstract:Despite their complex evolutionary histories, aquatic plants are highly underrepresented in contemporary biosystematic studies. Of them, the genus Callitriche is particularly interesting because of such evolutionary features as wide variation in chromosome numbers and pollination systems. However, taxonomic difficulties have prevented broader investigation of this genus. In this study we applied flow cytometry to Callitriche for the first time in order to gain an insight into evolutionary processes and genome size differentiation in the genus. Flow cytometry complemented by confirmation of chromosome counts was applied to an extensive dataset of 1077 Callitriche individuals from 495 localities in 11 European countries and the USA. Genome size was determined for 12 taxa. The results suggest that many important processes have interacted in the evolution of the genus, including polyploidization and hybridization. Incongruence between genome size and ploidy level, intraspecific variation in genome size, formation of autotriploid and hybridization between species with different pollination systems were also detected. Hybridization takes place particularly in the diploid – tetraploid complex C. cophocarpa – C. platycarpa, for which the triploid hybrids were frequently recorded in the area of co-occurrence of its parents. A hitherto unknown hybrid (probably C. hamulata × C. cophocarpa) with a unique chromosome number was discovered in the Czech Republic. However, hybridization occurs very rarely among most of the studied species. The main ecological preferences were also compared among the taxa collected. Although Callitriche taxa often grow in mixed populations, the ecological preferences of individual species are distinctly different in some cases. Anyway, flow cytometry is a very efficient method for taxonomic delimitation, determination and investigation of Callitriche species, and is even able to distinguish homoploid taxa and identify introduced species.
-
Flow cytometric results for 178 individuals of 12 Callitriche taxa, for which the genome size was determined using propidium iodide staining.
2014Co-Authors: Jan Prancl, Zdeněk Kaplan, Pavel Trávníček, Vlasta JarolimovaAbstract:* B = Bellis perennis (2C = 3.96 pg); G = Glycine max ‘Polanka’ (2C = 2.50 pg).** 1Cx-value cannot be meaningfully calculated due to aneuploid chromosome counts of these taxa.*** Callitriche hamulata has recently been assigned to C. brutia, as C. brutia var. hamulata (Kütz. ex W.D.J. Koch) Lansdown [39], [40]. Both taxa are closely related and can be distinguished morphologically perhaps only in their fertile terrestrial forms. Nevertheless, a thorough study of the entire C. brutia complex on a large geographic scale, supported by statistical and analytical methods, is not yet available. Callitriche brutia and C. hamulata possess distinct chromosome numbers and apparently have different evolutionary histories (although the histories of both species are completely unknown and perhaps complex). In addition, their distribution and habitat requirements are partially different. For these reasons, we retain separate taxonomic treatments of these species, at least until the complex is subjected to a critical review using appropriate genetic markers and the mechanism of its origin elucidated.Flow cytometric results for 178 individuals of 12 Callitriche taxa, for which the genome size was determined using propidium iodide staining.
-
Chromosome numbers of 8 Callitriche species counted in this study.
2014Co-Authors: Jan Prancl, Zdeněk Kaplan, Pavel Trávníček, Vlasta JarolimovaAbstract:*For samples details, see Table S2.Chromosome numbers of 8 Callitriche species counted in this study.
-
Flow cytometric analysis of Callitriche lenisulca with Bellis perennis as an internal standard, using propidium iodide staining.
2014Co-Authors: Jan Prancl, Zdeněk Kaplan, Pavel Trávníček, Vlasta JarolimovaAbstract:Flow cytometric analysis of Callitriche lenisulca with Bellis perennis as an internal standard, using propidium iodide staining.
-
Ecological preferences of 594 Callitriche samples of 9 species and 2 hybrids and co-ocurrence of particular taxa in mixed populations.
2014Co-Authors: Jan Prancl, Zdeněk Kaplan, Pavel Trávníček, Vlasta JarolimovaAbstract:* For details, see Materials and Methods.Ecological preferences of 594 Callitriche samples of 9 species and 2 hybrids and co-ocurrence of particular taxa in mixed populations.
Tjeerd Bouma - One of the best experts on this subject based on the ideXlab platform.
-
Turbulence‐mediated facilitation of resource uptake in patchy stream macrophytes
Limnology and Oceanography, 2019Co-Authors: Loreta Cornacchia, Sofia Licci, Heidi Nepf, Andrew Folkard, Daphne Wal, Johan Koppel, Sara Puijalon, Tjeerd BoumaAbstract:Many landscapes are characterized by a patchy, rather than homogeneous, distribution of vegetation. Often this patchiness is composed of single-species patches with contrasting traits, interacting with each other. To date, it is unknown whether patches of different species affect each other’s uptake of resources by altering hydrodynamic conditions, and how this depends on their spatial patch configuration. Patches of two contrasting aquatic macrophyte species (i.e., dense canopy-forming Callitriche and sparse canopy-forming Groenlandia) were grown together in a racetrack flume and placed in different patch configurations. We measured 15NH4+ uptake rates and hydrodynamic properties along the centerline and the lateral edge of both patches. When the species with a taller, denser canopy (Callitriche) was located upstream of the shorter, sparser species (Groenlandia), it generated turbulence in its wake that enhanced nutrient uptake for the sparser Groenlandia. At the same time, Callitriche benefited from being located at a leading edge where it was exposed to higher mean velocity, as its canopy was too dense for turbulence to penetrate from upstream. Consistent with this, we found that ammonium uptake rates depended on turbulence level for the sparse Groenlandia and on mean flow velocity for the dense Callitriche, but Total Kinetic Energy was the best descriptor of uptake rates for both species. By influencing turbulence, macrophyte species interact with each other through facilitation of resource uptake. Hence, heterogeneity due to multi-specific spatial patchiness has crucial implications for both species interactions and aquatic ecosystem functions, such as nitrogen retention.
Kaj Sand-jensen - One of the best experts on this subject based on the ideXlab platform.
-
Plant communities in lowland Danish streams: species composition and environmental factors
Aquatic Botany, 2000Co-Authors: Tenna Riis, Kaj Sand-jensen, Ole VestergaardAbstract:We studied the quantitative composition of the vegetation at 208 stream sites distributed throughout Denmark with the purpose of identifying distinct plant communities, using cluster analysis, and their relationship to environmental conditions using indirect gradient analysis. Six plant communities were defined in the analysis, although the differences in species composition among them were small. The plant communities were mainly related to differences in water alkalinity with a Potamogeton-community being associated with high alkalinities, Sparganium-, Callitriche- and Batrachium-communities with medium alkalinities and a Myriophyllum alterniflorum-community associated with low alkalinity. Also stream size turned out to be an important variable to the separation of plant communities, with the Callitriche-community mainly found in small streams and the Potamogeton-community and a community of amphibious helophytes mainly found in larger streams. The most common species were Sparganium emersum and Elodea canadensis forming the widespread Sparganium-community at half of the stream sites throughout Denmark, a pattern most likely stimulated by the common practice of weed cutting. Though communities of stream plants could be defined, the overlap of species among them was very substantial. Communities are less distinct in Danish streams compared to streams in other regions including wider environmental gradients of temperature, current velocity, substratum, alkalinity and nutrient richness.
-
Dynamic Properties of Recruitment, Expansion and Mortality of Macrophyte Patches in Streams
International Review of Hydrobiology, 1999Co-Authors: Kaj Sand-jensen, Karsten Wiber Andersen, Tine AndersenAbstract:Streams are physically perturbed habitats with high demands on the dispersal and recruitment to maintain plant populations. Yet, little is known about these important demographic processes for stream plants. Therefore, we studied the monospecific vegetation of Callitriche cophocarpa in a small Danish lowland stream to determine: 1) the importance of drifting shoots and seeds for recruitment of plants, and 2) the influence of water flow, light availability and patch size on recruitment, growth and mortality processes. We found that the majority (about 90%) of new colonising patches of plant stands derived from drifting shoots being caught around protruding stones, while few developed from seeds. Many new patches were lost in the flowing water before roots became well established. Flow exposure of the patches resulted in the main growth taking place in the downstream direction. Combined areal cover of Callitriche patches on the stream bottom reached an upper limit of about 70%, probably because areal expansion above this threshold was constrained by strong shear forces and coarse substrata developing in the flow channels between the patches. We discuss why efficient shoot dispersal and vegetative growth documented here for Callitriche is an optimal plant strategy in flow-perturbed streams in contrast to the production of numerous small seeds but limited vegetative spread among ruderal plants in perturbed habitats on land.
-
The interactive effects of light and inorganic carbon on aquatic plant growth
Plant Cell and Environment, 1994Co-Authors: Tom Vindbæk Madsen, Kaj Sand-jensenAbstract:Submerged aquatic macrophytes grow across a wide, often coupled, range of light and inorganic carbon availabilities, and each single factor influences photosynthesis and acclimation. Here we examine the interactive effects of light and inorganic carbon on the growth of Elodea canadensis and Callitriche cophocarpa. The plants were grown in the laboratory at a range of light intensities (0–108 μmol m−2s−1) and four inorganic carbon regimes in a crossed factorial design. Plant growth rates, measured over 3–4 weeks of incubation, increased in response to increasing light intensity and inorganic carbon availability, and significant interactive effects were observed. The light-use efficiency for growth at low light increased 2-fold for Callitriche and 6-fold for Elodea between the lowest and highest inorganic carbon concentrations applied. Also, the growth rate at the highest light intensity increased with inorganic carbon availability, but the relative increase was smaller than at low light. Both species acclimated to the light and carbon regime such that the chlorophyll content declined at low and high light intensities and the initial slopes of the photosynthetic CO2 and HCO3− response curves declined at high levels of CO2. Callitriche responded less markedly than Elodea to changing inorganic carbon availability during growth, and the initial slope of the photosynthetic HCO3− response curve, in particular, was greatly reduced (>90%) in Elodea by high CO2. It is suggested that the coupled responses of aquatic macrophytes to light and inorganic carbon influence their ability to develop dense stands at high light in shallow water and to extend to greater depths in waters rich in inorganic carbon.
Matthew T. Ó. Hare - One of the best experts on this subject based on the ideXlab platform.
-
invertebrate hydraulic microhabitat and community structure in Callitriche stagnalis scop patches
Hydrobiologia, 1999Co-Authors: Matthew T. Ó. Hare, Kevin MurphyAbstract:In this paper, we report the structure of the benthic invertebrate community in submerged Callitriche stagnalis Scop. stands in relation to velocity, in a Scottish river, the Blane Water. We compared the community within the macrophyte beds to that of adjacent unvegetated substrate. Callitriche stagnalis stands supported different taxa richness (no. of taxa) and abundances (no. of individuals) of benthic invertebrates than the unvegetated riffle substrate (Wilcoxon Matched-Pairs test: p<0.01, n = 10). To see if different sections of the stands supported different invertebrate communities, samples were taken from the outer, mid and root sections of the stands. The sections were separated by Detrended Correspondence Analysis (DCA) using their macroinvertebrate communities (eigenvalues: axis 1 = 0.6, axis 2 = 0.136). Abundance and taxa richness were different between the outer and mid sections, and between outer and root sections (Wilcoxon Matched-Pairs test: respectively p<0.05, p<0.01, n = 10). Community structure also differed between sections. The outer section community had a structure similar to that of an extreme environment where Simuliidae were dominant. Ephemerella ignita dominated in the mid and root sections. Differing combinations of plant structure and velocity appear to be a major factor influencing habitat structure, creating a range of stability conditions in the stands, which support the observed diversity of invertebrate assemblages present.
-
Invertebrate hydraulic microhabitat and community structure in Callitriche stagnalis Scop. patches
Biology Ecology and Management of Aquatic Plants, 1999Co-Authors: Matthew T. Ó. Hare, Kevin MurphyAbstract:In this paper, we report the structure of the benthic invertebrate community in submerged Callitriche stagnalis Scop. stands in relation to velocity, in a Scottish river, the Blane Water. We compared the community within the macrophyte beds to that of adjacent unvegetated substrate. Callitriche stagnalis stands supported different taxa richness (no. of taxa) and abundances (no. of individuals) of benthic invertebrates than the unvegetated riffle substrate (Wilcoxon Matched-Pairs test: p
