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Ecology Studies (ecology + studies)
Selected AbstractsOn the reproducibility of microcosm experiments , different community composition in parallel phototrophic biofilm microcosmsFEMS MICROBIOLOGY ECOLOGY, Issue 2 2006Guus Roeselers Abstract Phototrophic biofilms were cultivated simultaneously using the same inoculum in three identical flow-lane microcosms located in different laboratories. The growth rates of the biofilms were similar in the different microcosms, but denaturing gradient gel electrophoresis (DGGE) analysis of both 16S and 18S rRNA gene fragments showed that the communities developed differently in terms of species richness and community composition. One microcosm was dominated by Microcoleus and Phormidium species, the second microcosm was dominated by Synechocystis and Phormidium species, and the third microcosm was dominated by Microcoleus- and Planktothrix -affiliated species. No clear effect of light intensity on the cyanobacterial community composition was observed. In addition, DGGE profiles obtained from the cultivated biofilms showed a low resemblance with the profiles derived from the inoculum. These findings demonstrate that validation of reproducibility is essential for the use of microcosm systems in microbial ecology studies. [source] Influence of Environmental Heterogeneity on the Structure of Testate Amoebae (Protozoa, Rhizopoda) Assemblages in the Plankton of the Upper Paraná River Floodplain, BrazilINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2003Luiz Felipe Machado Velho Abstract In freshwater environments, testate amoebae are usually found associated with macrophytes and sediments and many studies have suggested that their occurrence in plankton samples is accidental. This implies that predictable patterns detected in planktonic assemblages should not be observed in testate amoebae assemblages. This hypothesis was tested in this study. Plankton samples were collected from different environments in the Upper Paraná River floodplain. Results show that patterns in species composition and abundance of testate amoebae are predictable, and that dominant species tend to present characteristic shell morphology in hydrologically different environments. We suggest that testate amoebae must be routinely included in plankton ecology studies, at least in floodplain environments. [source] Changes in the rRNA levels of specific microbial groups in activated sludge during sample handling and storageLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2005J.E. Keith Abstract Aims:, To quantitatively analyse the changes in group-specific rRNA levels in activated sludge as a function of sample handling and storage procedure. Methods and Results:, Quantitative membrane hybridizations with 32P-labelled oligonucleotide probes were used to analyse the effects of different sample handling and storage conditions on the relative rRNA levels of the alpha, beta, and gamma-Proteobacteria, the Cytophaga-Flavobacteria group, and the mycolic acid-containing actinomycetes in activated sludge. Group-specific rRNA levels, expressed as percentages of total 16S rRNA detected with a universal probe, in samples maintained at room temperature significantly changed after 48 h. Group-specific rRNA levels in samples treated with chloramphenicol showed significant change after 72 h. Conclusions:, Sample storage at room temperature is a viable option if freezing or analysis can be performed within 24 h, while treatment with chlorampenicol can extend that time to at least 48 h. Significance and Impact of the Study:, Handling, shipping, and storage of environmental samples under several conditions may result in inaccurate determination of the microbial populations in microbial ecology studies. [source] Food mechanical properties in three sympatric species of Hapalemur in Ranomafana National Park, MadagascarAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009Nayuta Yamashita Abstract We investigated mechanical dietary properties of sympatric bamboo lemurs, Hapalemur g. griseus, H. aureus, and H. (Prolemur) simus, in Ranomafana National Park, Madagascar. Each lemur species relies on bamboo, though previous behavioral observations found that they specialize on different parts of a common resource (Tan: Int J Primatol 20 1999 547,566; Tan: PhD dissertation 2000 State University of New York, Stony Brook). On the basis of these earlier behavioral ecology studies, we hypothesized that specialization on bamboo is related to differences in mechanical properties of specific parts. We quantified mechanical properties of individual plant parts from the diets of the bamboo lemur species using a portable tester. The diets of the Hapalemur spp. exhibited high levels of mechanical heterogeneity. The lemurs, however, could be segregated based on the most challenging (i.e., mechanically demanding) foods. Giant bamboo culm pith was the toughest and stiffest food eaten, and its sole lemur consumer, H. simus, had the most challenging diet. However, the mechanical dietary properties of H. simus and H. aureus overlapped considerably. In the cases where lemur species converged on the same bamboo part, the size of the part eaten increased with body size. Plant parts that were harvested orally but not necessarily masticated were the most demanding, indicating that food preparation may place significant loads on the masticatory apparatus. Finally, we describe how mechanical properties can influence feeding behavior. The elaborate procurement processes of H. simus feeding on culm pith and H. griseus and H. aureus feeding on young leaf bases are related to the toughnesses of protective coverings and the lemurs' exploitation of mechanical vulnerabilities in these plants. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] |