Selective grazing of burned patches can be intense if animal distribution is not controlled and may compound the independent effects of fire and grazing on soil characteristics. Our objectives were to quantify the effects of patch burning and grazing on wind erosion, soil water content, and soil temperature in sand sagebrush (Artemisia filifolia Torr.) mixed prairie. We selected 24, 4-ha plots ...

Top-down grazer control of cyanobacteria is a controversial topic due to conflicting reports of success and failure as well as a bias toward studies in temperate climates with large generalist grazers like Daphnia. In the tropical lowland lakes of Brazil, calanoid copepods of the Notodiaptomus complex dominate zooplankton and co-exist in high abundance with permanent blooms of toxic cyanobacter...

Livestock have been a key factor in the development of civiliiation, hut what will their role be in the future and how should the science of rangeland management change to meet the challenges of the future? In this paper I look at current grazing management in the contest of paradigm shifts and scientific revolution. The impact of livestock on rangelands occurs primarily because livestock selec...

We examined whether virus infection of Emiliania huxleyi with the lytic E. huxleyi-specific virus, EhV-86, influenced it’s palatability to the heterotrophic dinoflagellate Oxyrrhis marina. E. huxleyi mortality was assessed by comparing changes in the algae’s concentration between four different incubations: (1) Grazer O. marina plus an equal concentration of infected and healthy E. huxleyi prey...

Selective grazing by protists can profoundly influence bacterial community structure, and yet direct, quantitative observation of grazing selectivity has been difficult to achieve. In this investigation, flow cytometry was used to study grazing by the marine heterotrophic flagellate Paraphysomonas imperforata on live bacterial cells genetically modified to express the fluorescent protein marker...

We analyzed changes in bacterioplankton morphology and composition during enhanced protozoan grazing by image analysis and fluorescent in situ hybridization with group-specific rRNA-targeted oligonucleotide probes. Enclosure experiments were conducted in a small, fishless freshwater pond which was dominated by the cladoceran Daphnia magna. The removal of metazooplankton enhanced protozoan grazi...

We tested the impact of bacterial swimming speed on the survival of planktonic bacteria in the presence of protozoan grazers. Grazing experiments with three common bacterivorous nanoflagellates revealed low clearance rates for highly motile bacteria. High-resolution video microscopy demonstrated that the number of predator-prey contacts increased with bacterial swimming speed, but ingestion rat...

To many pathogenic bacteria, human hosts are an evolutionary dead end. This begs the question what evolutionary forces have shaped their virulence traits. Why are these bacteria so virulent? The coincidental evolution hypothesis suggests that such virulence factors result from adaptation to other ecological niches. In particular, virulence traits in bacteria might result from selective pressure...

Herbivory and bacterivory by phagotrophic protists were estimated in the southern basin of the oligotrophic Lake Tanganyika at different seasons (in the rainy season in February–March 2007 and in the dry season in July–August 2006 and September 2007), using two independent methods: the selective inhibitor technique for assessing community grazing on picocyanobacteria (PCya) and fluorescently la...