1,720,972 research outputs found
The effect of nematodes on activity and abundance of bacteria in a profundal freshwater sediment
No full textTraunspurger W, Bergtold M, Goedkoop W. The effect of nematodes on activity and abundance of bacteria in a profundal freshwater sediment. Oecologia. 1997;112:118-122
Production of freshwater nematodes
No full textBergtold M, Traunspurger W. Production of freshwater nematodes. In: Abebe E, Andrassy I, Traunspurger W, eds. Freshwater Nematodes: Ecology and taxonomy. Wallingford: CAB International; 2006: 752
Refractory dissolved organic matter can influence the reproduction of Caenorhabditis elegans (Nematoda.
No full textHoess S, Bergtold M, Haitzer M, Steinberg CEW, Traunspurger W. Refractory dissolved organic matter can influence the reproduction of Caenorhabditis elegans (Nematoda. Freshwater Biology. 2001;46:1-10
The share of benthic production by micro-, meio-, and macrobenthos in the profundal of an oligotrophic lake
No full textBergtold M, Traunspurger W. The share of benthic production by micro-, meio-, and macrobenthos in the profundal of an oligotrophic lake. Journal of North American Benthological Society. 2005;24(2):321-329
Feeding ecology of free-living benthic nematodes
No full textMoens T, Bergtold M, Traunspurger W. Feeding ecology of free-living benthic nematodes. In: Abebe E, Andrassy I, Traunspurger W, eds. Freshwater Nematodes: Ecology and taxonomy. Wallingford: CAB International; 2006: 752
Patterns in the size structure of freshwater nematode communities: The cases of lakes Königssee and Brunnsee, Germany
No full textTraunspurger W, Bergtold M. Patterns in the size structure of freshwater nematode communities: The cases of lakes Königssee and Brunnsee, Germany. In: Abebe E, Andrassy I, Traunspurger W, eds. Freshwater nematodes ecology and taxonomy. Wallingford: CAB International; 2006: 132-143
The effect of sedimentation on the benthic community of Lake Brunnsee
No full textBergtold M, Traunspurger W. The effect of sedimentation on the benthic community of Lake Brunnsee. Archiv für Hydrobiologie. 2005;163(3):287-305.The flux of settling particles to the sediment was manipulated in a field and laboratory experiment. In the field, sedimentation rate was reduced in experimental areas by a factor of 2.3 by covering the bottom of the lake. Sedimentation rate, bacterial parameters, as well as protozoan and metazoan abundance were recorded over a period of 8 month. The benthic community showed strong seasonal variation but did not respond to the reduced sedimentation rate in the field. In autumn, undisturbed sediment cores from the study site were transferred to the laboratory. Material from the lake was collected in sedimentation traps and continuously added to half of the cores over a period of 3 months. Controls received no material. The abundance of flagellates, ciliates and nematodes was higher in the treatments receiving material from the lake, though the effect was restricted to the uppermost sediment layer (0-0.5 cm). This study shows that sedimentation was of minor importance for the population dynamics of the organisms in the field, but turned out to be an important factor for a specific part of the benthic community under controlled laboratory conditions
The benthic community in the profundal of Lake Brunnsee: seasonal and spatial patterns
No full textBergtold M, Traunspurger W. The benthic community in the profundal of Lake Brunnsee: seasonal and spatial patterns. Archiv für Hydrobiologie. 2004;160(4):527-554.The seasonal distribution of bacteria, flagellates, ciliates, and selected metazoan organisms was investigated in the profundal sediment (18 m depth) of oligotrophic Lake Brunnsee (Germany) over a period of one year (April 1997 to April 1998). Most of the organisms displayed seasonal fluctuation with high abundance in summer and lower spring and autumn densities. Bacteria reached densities up to 2.1 x 10(10) cells/ml, with highest production values in July. Flagellates and ciliates had densities up to 151000 and 4100 cells/ml, respectively. Metazoan organisms were dominated by nematodes with a relative proportion of 76.4%, followed by rotifers with 6.5%. Other benthic taxa contributed less than 5% to overall abundance. Biotic and abiotic variables were tested for their ability to explain the variance in abundance of benthic organisms by means of multiple regression analyses. Vertical distribution of the metazoan organisms was recorded to a sediment depth of 4 cm. Most organisms preferred the uppermost centimetre. Rotifers and gastrotrichs have rarely been found (<15%) below 1 cm depth, while copepods and mites penetrate deeper (more than 60% have been found between 1 and 4 cm sediment depth). Spatial variation in abundance was recorded at a single sampling occasion by taking 16 sediment cores from the profundal of the lake. The spatial variation (differences between the cores) was highest for ciliates and bacteria and low for organic carbon, bacterial production, and bacterial extracellular activity
Nematodes in wastewater biofilms - Appearance and density of species in three biofilter reactors
No full textBergtold M, Mayr G, Traunspurger W. Nematodes in wastewater biofilms - Appearance and density of species in three biofilter reactors. WATER RESEARCH. 2007;41(1):145-151.Population dynamics of nematode species in biofilms of three different biofilter reactors, differing in size (pilot/laboratory scale), operation mode and biofilm carrier, were studied over a period of 1 year. In the biofilm. suspension of the pilot system mean nematode density was 118 individuals/ml and average biomass 15 mu g wet weight/ml. Higher mean abundance was found in the two laboratory systems with 2380 and 4411 individuals/ml. Mean biomass in the laboratory systems ranged from 209 to 330 mu g wet weight/ml. There were marked temporal differences in appearance and density of nematode species in all three biofilters. Number of species observed was 3 in the laboratory systems and 5 in the pilot system. The fastest growing species (Paroigolaimella bernensis and Diplogasteritus nudicapitatus) were observed in the pilot reactor in contrast to the more slowly growing species (Diploscapter coronatus and Acrostichus sp.), which dominated in the laboratory reactors. Sexual reproduction was found for all species but of Diploscapter coronatus. When comparing life history traits of the different species with the environmental conditions in the reactors, it seems that the unstable conditions in the pilot reactor favor the fast growing species whereas the stable environment in the laboratory systems allows the growth of species with longer generation times. (c) 2006 Elsevier Ltd. All rights reserved
Is there competition among ciliates and nematodes?
No full textBergtold M, Gunther V, Traunspurger W. Is there competition among ciliates and nematodes? FRESHWATER BIOLOGY. 2005;50(8):1351-1359.1. Biotic interaction between the ciliate Cyclidium glaucoma and the nematode Caenorhabditis elegans was investigated by manipulating the densities of the organisms in microcosms with and without sediment. 2. After 11 days the abundance of ciliates, nematodes and bacteria as well as extracellular enzyme activity were determined. Ciliates had a negative effect on nematode abundance in microcosms without sediment and in microcosms with sandy sediment, whereas in muddy sediment the effect was less distinctive. An effect of nematodes on ciliates was not observed. 3. The common resource bacteria were not affected negatively by the activity of the grazers. Overall grazer biomass increased with the addition of sediment to the microcosms, suggesting a rise of the carrying capacity in the experimental system. Especially in muddy sediment the abundance of bacteria and extracellular enzyme activity was higher compared to the microcosms without sediment. 4. The results of the experiment suggest a strong interspecific competition between nematodes and ciliates, where nematodes are, at least temporary, strongly affected
- …
