Source Ecosystem Research Articles

Open source business models: ready for prime time

Open source software was ready for any enterprise by putting its full corporate support behind Linux, the open source ecosystem has matured into a shoulder-to-shoulder companion for commercial proprietary software. A new tapestry of community resources, venture capital, and informal networks of open source veterans championing new applications is being woven through industries and academia. What open source software really does is open up the low end of the market, and it certainly changes dynamics on the global stage.

Ecological scaling of aerobiological dispersal processes

A variety of organisms change their geographic locations during their life history, and many use the atmosphere to accomplish this shift. Biota that flow in the atmosphere range from very small (viruses, bacteria, pollen, and spores) to quite large (weed seeds, aphids, butterflies and moths, songbirds, and waterfowl). As these organisms move, they experience meteorological and ecological conditions that occur at a wide range of spatial and temporal scales. We present an ecological scaling approach that integrates concepts and elements of spatial and temporal scaling to understanding aerobiology and provide examples of the ecological scales important to the long-distance aerial movement of organisms and associated biological events and processes. An operational framework for ecological scaling of long distance biota movement is achieved by linking spatially-static ecoregion classification systems with temporally-dynamic measures of vegetation phenology. The ecoregions provide ecological boundaries for the phenological dynamics of plants. Operationally, this approach integrates the bi-weekly vegetation greening indices (NDVI) derived from AVHRR or TM satellite data (representing temporal scaling) with the less dynamic land cover–land use classification (IGBP) and the relatively static ecoregion boundaries (representing the spatial scaling). We argue that the correlation of the life histories of species, especially the timing of take-off, to ecosystem phenology through meteorological-based variables and indices (e.g., degree days and moisture indices), allows for dynamic characterization of source ecosystems and can be used to parameterize atmospheric models to forecast the flow of biota in the air. The scale of these processes, the diversity of the types of biota involved in long-distance movement, and the complexity of the processes require systems thinking. We anticipate that this paper will stimulate studies to enhance our understanding of the flow of organisms in the biosphere.

Validation of microbial community structure and ecological functional parameters in an aquatic microcosm designed for testing genetically engineered microorganisms

Microcosms were designed to facilitate studies of the fate, functioning, and ecological effects of microorganisms released into the aquatic environment. The microcosms were three-phase systems (sediment/water/air) with three compartments (a primary producer component, a herbivore grazer component, and intact sediment cores). The microcosms were validated by comparing gross ecological parameters and microbial community structure between the microcosms and the eutrophic Lake Bagsværd, which was simulated in the model. The photosynthetic potential and chlorophyll a concentrations were significantly lower in the microcosms than in the lake, which apparently was due to inorganic nutrient limitation. In the microcosms, total bacterial numbers and metabolic activity by [(3)H]thymidine incorporation were unaffected by the reduced algal biomass and primary production, simulating field conditions closely, with a strong dependence on temperature. Two days after filling the microcosms, the percentage of similarity of the microbial communities in the microcosm and Lake Bagsværd was 40%, measured by hybridizations of total microbial DNA. The similarity increased during the 10-day experimental period to 63-76%. In two experiments, Alcaligenes eutrophus AEO106(pRO101) was released into the microcosms. The release reduced the similarity between microcosms and lake to 2% and 27%, depending on the number of introduced cells. Concomitant to a decline in the A. eutrophus AEO106(pRO101) population, the similarity gradually recovered. It is concluded that the microcosms can simulate a freshwater lake ecosystem, but care has to be taken when extrapolating microcosm results to the source ecosystem because of the possible different selective conditions in the microcosm.

Evaluation of aquatic sediment microcosms and their use in assessing possible effects of introduced microorganisms on ecosystem parameters.

In this paper we describe a sediment microcosm system consisting of 20 undisturbed, layered sediment cores with overlying site water which are incubated under identical conditions of temperature, light, stirring rate of overlying water, and water exchange rate. Ecosystem parameters (nutrient level, photosynthetic potential, community structure of heterotrophic bacteria, thymidine incorporation rate, and oxygen microgradients) of the laboratory microcosms and the source ecosystem were compared and shown to be indistinguishable for the first 2 weeks. In weeks 3 and 4, small differences were detectable in the nutrient level, community structure of heterotrophic bacteria, and thymidine incorporation rate. However, the photosynthetic potential, depth profiles of heterotrophic bacterial community structure, and oxygen microgradients were maintained throughout the incubation period and did not differ between laboratory microcosms and the source ecosystem. The microcosm system described here would thus appear to be a valid model of aquatic sediments for up to 4 weeks; the actual period would depend on the sediment source and incubation temperature. The validated systems were used with Rhine river sediment to assess possible effects on ecosystem parameters of Pseudomonas sp. strain B13 FR1(pFRC20P), a genetically engineered microorganism (GEM) that had been constructed to degrade mixtures of halo- and alkylbenzoates and -phenols. The GEM survived in the surface sediment at densities of 5 x 10(4) to 5 x 10(5)/g (dry weight) for 4 weeks and degraded added chloro- and methylaromatics. The GEM did not measurably influence ecosystem parameters such as photosynthesis, densities of selected heterotrophic bacteria, thymidine incorporation rate, and oxygen microgradients. Thus, the microcosm system described here would seem to be useful for the study of the ecology of biodegradation and the fate and effect of microorganisms introduced into the environment.

Ecosystem contrasts in interaction with the planetary boundary layer 1)1)1)

In many climatic regions the interface between the earth and the atmosphere consists of a mosaic of ecosystems, each possessing specific properties of absorbing and storing energy and matter. Large contrasts in these properties create differences in interface temperature and moisture, which, in combination with contrasts in roughness, produce differences in sensible and latent heat fluxes injected into the atmosphere, so that the boundary layer experiences rapid alterations to its structure and transport of energy and matter. In consequence, good data on fluxes from individual ecosystems and their contrasts are essential both to understanding the functioning of the boundary layer and energy/mass accounting at source and sink ecosystems.