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Results for “ecosystem engineer”

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At least 145 records · Page 8Linked to original sources
PubMed1996

Use of green fluorescent protein to monitor survival of genetically engineered bacteria in aquatic environments.

Many methods for detecting model genetically engineered microorganisms (GEMs) in experimental ecosystems rely on cultivation of introduced cells. In this study, survival of Escherichia coli was monitored with the green fluorescent protein (GFP) gene. This approach allowed enumeration of GEMs by both plating and microscopy. Use of the GFP-marked GEMs revealed that E. coli persisted in stream water at higher densities as determined microscopically than as determined by CFU enumeration. The GFP gene did not negatively impact the fitness of the host strain.

Escherichia coli↗
PubMed2004

Risk assessment of heavy metal pollution for detritivores in floodplain soils in the Biesbosch, The Netherlands, taking bioavailability into account.

Floodplains of the European rivers Rhine and Meuse are heavily polluted. We investigated the risk of heavy metal pollution (Cd, Cu, Pb, Zn) for detritivores living in a floodplain area, the Biesbosch, the Netherlands, affected by these rivers. Total soil, pore water and 0.01 M CaCl(2) extractable concentrations and concentrations in plant leaves, earthworms, isopods and millipedes were measured in two sites and compared with literature data to assess possible risks. Based on total metal concentrations in soil, serious effects on detritivores were expected. However, 0.01 M CaCl(2) extractable, pore water and plant leaf concentrations were similar to metal concentrations found in unpolluted areas. Concentrations of Cu and Cd in earthworms and Cu in millipedes were higher in the Biesbosch than in animals from reference areas. All other measured concentrations of heavy metals in earthworms, isopods and millipedes were similar to the ones found in reference areas. Despite high total soil concentrations, effects of Zn, Cu, Pb and Cd pollution on isopods are therefore not expected, while millipedes may only be affected by Cu. Since Cu and Cd levels in earthworms were increased compared to animals in unpolluted soils, this faunal group seems to be most at risk. Given the engineering role of earthworms in ecosystems, effects on the ecological functioning of floodplain soils therefore cannot be excluded.

Animals↗
PubMed2001

[Discussion on some basic problems in design of wetland ecosystem].

The design of wetland ecosystem is the key and fundament in wetland restoration and mitigation. In recent years, it has been frequently applied to the proper construction of wetlands. The paper first reviews the concept of wetland ecosystem design, as well as the basis of ecological engineering, and then presented the basic principles in the design of wetland ecosystem. Some major ecological indicators including hydrology, chemical, substrate, soil and biotic indicators were also discussed, and some reference values for ecological indicators were presented. On the base of the designing purposes, three major types in the wetland design were analysed. They include constructing wetlands for wastewater treatment, for mitigation wetlands, and for controlling flooding and non-point source pollution.

Ecosystem↗
PubMed2001

"Living off the land": resource efficiency of wetland wastewater treatment.

Bioregenerative life support technologies for space application are advantageous if they can be constructed using locally available materials, and rely on renewable energy resources, lessening the need for launch and resupply of materials. These same characteristics are desirable in the global Earth environment because such technologies are more affordable by developing countries, and are more sustainable long-term since they utilize less non-renewable, imported resources. Subsurface flow wetlands (wastewater gardens(TM)) were developed and evaluated for wastewater recycling along the coast of Yucatan. Emergy evaluations, a measure of the environmental and human economic resource utilization, showed that compared to conventional sewage treatment, wetland wastewater treatment systems use far less imported and purchased materials. Wetland systems are also less energy-dependent, lessening dependence on electrical infrastructure, and require simpler maintenance since the system largely relies on the ecological action of microbes and plants for their efficacy. Detailed emergy evaluations showed that wetland systems use only about 15% the purchased emergy of conventional sewage systems, and that renewable resources contribute 60% of total emergy used (excluding the sewage itself) compared to less than 1% use of renewable resources in the high-tech systems. Applied on a larger scale for development in third world countries, wetland systems would require the electrical energy of conventional sewage treatment (package plants), and save of total capital and operating expenses over a 20-year timeframe. In addition, there are numerous secondary benefits from wetland systems including fiber/fodder/food from the wetland plants, creation of ecosystems of high biodiversity with animal habitat value, and aesthestic/landscape enhancement of the community. Wetland wastewater treatment is an exemplar of ecological engineering in that it creates an interface ecosystem to handle byproducts of the human economy, maximizing performance of the both the natural economy and natural ecosystems. Wetland systems accomplish this with far greater resource economy than other sewage treatment approaches, and thus offer benefits for both space and Earth applications.

Conservation of Natural Resources↗
PubMed2002

Neural network modeling of salinity variation in Apalachicola River.

Salinity is an important indicator for water quality and aquatic ecosystem in tidal rivers. The increase of salinity intrusion in a river may have an adverse effect on the aquatic environment system. This study presents an application of the artificial neural network (ANN) to assess salinity variation responding to the multiple forcing functions of freshwater input, tide, and wind in Apalachicola River, Florida. Parameters in the neural network model were trained until the model predictions of salinity matched well with the observations. Then, the trained model was validated by applying the model to another independent data set. The results indicate that the ANN model is capable of correlating the non-linear time series of salinity to the multiple forcing signals of wind, tides. and freshwater input in the Apalachicola River. This study suggests that the ANN model is an easy-to-use modeling tool for engineers and water resource managers to obtain a quick preliminary assessment of salinity variation in response to the engineering modifications to the river system.

Conservation of Natural Resources↗
PubMedDate not supplied

Brave new birds. The use of 'animal integrity' in animal ethics.

Suppose "chicken" eggs could be produced by quasi-chickens--genetically engineered humps of living chicken-flesh that do nothing but lay eggs. Would there be anything amiss with that? Animal ethicists invoke the notion of animal integrity in order to give intellectual content to the intuition that there would be. On inspection, 'integrity' isn't everything its proponents want it to be. Yet there's enough in it to make reasoned argument possible.

Animal Rights↗
PubMed1997

Genetically engineered plants producing opines alter their biological environment.

Little is known about the consequences of releasing genetically engineered plants (GEP) into the environment. Using opine-producing GEP, we show that transgenic plants alter their biological environment, more precisely the root-associated bacterial populations. The alterations were both transgene-specific and target population-specific. Therefore, assessment studies on the introduction of a given transgene into a GEP will be valid on the given transgene. Evidence of any transgene-associated biological effect will depend on the determination of the pertinent target populations, the identification of which is a key step of such studies.

Bacteria↗
PubMed2002

Ecophysiology and breeding of mycoparasitic Trichoderma strains (a review).

Losses due to plant diseases may be as high as 10-20% of the total worldwide food production every year, resulting in economic losses amounting to many billions of dollars and diminished food supplies. Chemical control involves the use of chemical pesticides to eradicate or reduce the populations of pathogens or to protect the plants from infection by pathogens. For some diseases chemical control is very effective, but it is often non-specific in its effects, killing beneficial organisms as well as pathogens, and it may have undesirable health, safety, and environmental risks. Biological control involves the use of one or more biological organisms to control the pathogens or diseases. Biological control is more specialized and uses specific microorganisms that attack or interfere with the pathogens. The members of the genus Trichoderma are very promising against soil-born plant parasitic fungi. These filamentous fungi are very widespread in nature, with high population densities in soils and plant litters [1]. They are saprophytic, quickly growing and easy to culture and they can produce large amounts of conidia with long lifetime.

Antibiosis↗
PubMed1999

Conjugative plasmid transfer between Pseudomonas strains within alginate bead microcosms: effect of the internal gel structure.

Because microorganisms frequently live in an immobilized state in natural habitats, a cell-confined system was used to study bacterial conjugation. Two Pseudomonas putida strains were introduced together within calcium alginate gels. Different alginate beads were designed by varying the polysaccharide and the gelation solution concentrations. Microscopic examinations showed that 2% gels were quite homogeneous, but that 1.5% and 1% gels were rather heterogeneous. In these two last cases, shaft-shaped macrostructures were present. They were colonized during the culture by great densities of highly motile bacteria. Gene transfers due to conjugation were investigated in such alginate gel bead microcosms, in batch and continuous cultures. High-initial transfer frequencies were detected whatever the gel, but no conjugation events seemed to occur with further growth in the beads. Transfer frequency values were roughly similar in the different tested systems. Alginate gels used as artificial microcosms may be valuable to study the effect of cell microenvironment on genetic transfers in complex systems.

Alginates↗
PubMed2006

Soil uptake of carbon monoxide emitted in the exhaust of a gasoline-powered engine.

Carbon monoxide (CO) poses dangers to both human and environmental health, sickening thousands of people annually in the United States and decreasing the capacity of the atmosphere to oxidize greenhouse gases. Globally, soil ecosystems with their populations of bacteria, fungi, and algae are estimated to remove 9-36% of total CO emissions, which makes them the second largest CO sink after hydroxyl oxidation. Our aim was determine whether soil ecosystems could remove CO from an atmosphere mixed with gasoline-powered engine exhaust. Sealed microcosms containing no soil (NoSoil), nonvegetated soil (Soil), or vegetated soil (Soil+Veg), were exposed to 800, 100, and 50 ppm of CO for 1 hr. The uptake rate of CO was found to be higher at the 800 ppm level suggesting first-order rate kinetics. Soil+Veg exhibited a significantly higher CO uptake rate than either Soil or NoSoil (P<0.05), and Soil exhibited significantly higher uptake than NoSoil (P<0.05). As a free ecosystem service, the uptake of CO by soil ecosystems needs to be properly valued and ecologically engineered into the urban traffic network in a manner analogous to how wetlands, vegetated swales, and other ecologically based storm water treatment systems have improved urban runoff.

Air Pollutants↗
PubMed1991

Biosphere II: engineering of manned, closed ecological systems.

Space Biospheres and Ventures, a private, for-profit firm, has undertaken a major research and development project in the study of biospheres, with the objective of creating and producing biospheres. Biosphere II-scheduled for completion in March 1991-will be essentially isolated from the existing biosphere by a closed structure, composed of components derived from the existing biosphere. Like the biosphere of the Earth, Biosphere II will be essentially closed to exchanges of material or living organisms with the surrounding environment and open to energy and information exchanges. Also, like the biosphere of the Earth, Biosphere II will contain five kingdoms of life, a variety of ecosystems, plus humankind, culture, and technics. The system is designed to be complex, stable and evolving throughout its intended 100-year lifespan, rather than static. Biosphere II will cover approximately 1.3 hectare and contain 200,000 m3 in volume, with seven major biomes: tropical rainforest, tropical savannah, marsh, marine, desert, intensive agriculture, and human habitat. An interdisciplinary team of leading scientific, ecological, management, architectural, and engineering consultants have been contracted by Space Biospheres Ventures for the project. Potential applications for biospheric systems include scientific and ecological management research, refuges for endangered species, and life habitats for manned stations on spacecraft or other planets.

Agriculture↗