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Popular Features. New Releases. Description This book bridges the gap between ecotoxicology and limnology, offering an ecotoxicological perspective on lake management. The text describes eutrophication of shallow, temperate lakes, and examines the influence of toxic substances on the aquatic ecosystem, and proposes that nutrients like phosphorus are not the only important factor in explaining and managing eutrophication. Draws on a range of studies and experiments, some presented here for the first time. Product details Format Paperback pages Dimensions x x 7. Other books in this series.

Add to basket. Mercury Contaminated Sites Ralf Ebinghaus. Nature Conservation Dan Gafta. Photobiogeochemistry of Organic Matter Khan M.

Novel Biomaterials Shalini Srivastava. Artificial Neuronal Networks Sovan Lek. Drying processes may produce coarse and fine particulates, including algae and lysed algae. The concentrations of particulates in air will depend on the technologies used; for example, belt dryers and convective systems will lead to greater local emissions than passive solar drying. Whether emissions move beyond the facility will depend on the level of containment. Particulates could be an occupational hazard even in closed facilities. In confined areas, dust could be an explosion hazard.

Poor drying methods also can give rise to decomposition of biomass and release of VOCs, amines, methane, and other compounds. Most proposed algal biofuel processing methods involve extraction of lipids or other compounds from cells using organic solvents. Extraction with organic chemicals, by necessity, results in some solvent emissions, and the quantities emitted depend on the technology applied.

The most common solvent that is openly discussed by manufacturers is hexane Demirbas, ; Lardon et al. In an environmental assessment, Sapphire Energy, Inc. Desirable properties of these solvents are low cost, recoverability, low toxicity, nonpolar structure, and poor extractor of non-lipid cell components Rawat et al.

Hexane is used as an extractant of vegetable oils in biodiesel production with fugitive hexane emissions Hess et al. Compliance with regulatory standards likely would minimize release of solvents. Technologies to convert total biomass to drop-in liquid fuels are being tested.

These processes may have additional feed inputs and will have different air emissions from those from production of esterified or green diesels. Pyrolysis of biomass yields three energy products—solids char , liquids bio-oils , and gases—in various proportions depending on the temperature, pressure, residence time, and other factors. The gases are recycled to provide energy for the system and thus do not contribute directly to air emissions except for any fugitive emissions that might escape the system.

The heating of the pyrolysis units might contribute a small amount of NOx and carbon monoxide CO. Additional energy, likely supplied by natural gas may be required to sufficiently dry the algal biomass prior to pyrolysis. Particulate emissions, acid gases, and hydrocarbon emissions from pyrolysis are not characterized in the literature. The bio-oil produced from whole-cell pyrolysis will require additional upgrading to produce transportation fuels.

The upgrading can be done with a separate hydrotreating step or a process similar to the Integrated Hydropyrolysis and Hydroconversion process. In either case, input of hydrogen is required. The production of hydrogen produces low levels of NOx Spath and Mann, and makes a CO 2 stream that could be used to supply the algae cultivation.

Anaerobic digestion for processing wastewater from algal biofuel production facilities is described in Chapter 2. NH 3 has been observed to be present in biogas from anaerobic digestion at concentrations up to ppm Schomaker, The concentration of NH 3 in biogas would depend on the nitrogen content of the particular feed material.

Early work by Golueke et al. NH 3 would not be released to air around the facility because of the desire to recycle nutrients required for cultivation. The primary categories of environmental effects associated with the end use of biofuels in vehicles are evaporative emissions and tailpipe emissions from fuel combustion. Fischer-Tropsch F-T synthesis converts a mixture of CO and hydrogen which may be derived from biomass into liquid hydrocarbons. Generally, the type and quantities of emissions vary depending on fuel characteristics for example, chemical properties and blends , age of the vehicle or other equipment, power output of engine, operating condition of engine, how the vehicle or other equipment is operated, and ambient temperature Graham et al.

Using biofuels in place of petroleum-based fuels decreases emissions of some air pollutants while increasing others Table ; NRC, EPA established emission standards for tailpipe emissions of CO, hydrocarbons, NOx, and particulate matter to which vehicle manufacturers and refiners have to comply EPA, a. Emissions of air pollutants need to be assessed over the life cycle of algal biofuels and compared to petroleum-based fuels and other alternatives. The Hill et al. They found that although the uses of gasoline and terrestrial-plant biofuels corn-grain ethanol and cellulosic ethanol release similar amounts of VOC, PM, NO x , SO x , and NH 3 , emissions from the production stages are significantly different between petroleum-based fuels and biofuels.

The committee is not aware of any LCA of such air pollutants for algal biofuels. Such analysis is critical in assessing whether biofuel production and use result in air quality improvement compared to fossil fuel and it provides information on stages in the supply chain that are key contributors to air pollutants.

Particulate emissions, hydrocarbon slip, and acid gases all possible from combustion of off-gas. With respect to air quality, the differences in expected effects among the pathways in Chapter 3 depend on the type of culture system open versus closed , the drying process, and whether or not extraction and pyrolysis steps are present in the pathway Table Algae produce a number of aerosols and secondary metabolites, some of which may be noxious for example, malodorous or harmful to humans.

Similarly, some supply-chain processes, such as extraction and drying, may emit solvents or particulates that could affect local air quality if not contained. If an algal biofuel facility is located near human populations, measures likely will be taken to contain or limit the release of any products that negatively affect local air quality or are perceived to be a risk to public health.

The health costs of some types of air emissions were discussed in Hill et al. Depending on the quantity of these outputs, and the proximity of population centers to a production facility, the reduction in air quality and perceived health and quality-of-life risks may impact the. If the public is not made aware of these potential effects prior to the siting and permitting of a facility, there is a risk that the production of undesirable compounds will be viewed as unacceptable after the construction of the facility has been completed.

If this is the case, litigation or protests may slow or shut down operations, resulting in financial losses for the developer and negative attention for the industry at large. The more contained a process is, whether it is the biomass cultivation process, drying, solvent extraction, pyrolysis, or digestion, the lower the emissions to air will be. Therefore, photobioreactors could have reduced air-quality impacts compared to open-pond systems. However, full LCA of the air pollutant emissions associated with the production of the bioreactor materials and system operation also would be needed to assess whether photobioreactors represent a small or negligible impact on air quality.

Although passive processes for example, solar drying reduce air quality impacts compared to active processes that generate dust or increase volatilization rates, they are not practical solutions at large scale. Siting facilities at a distance from human population centers and ecological species of concern would mitigate potential adverse effects of air pollution on humans. Appropriate sustainability metrics for air quality would depend on the processes used in algal biofuel production.

Concentrations would have to be measured or modeled at scales appropriate to bound regulatory levels or potential human health or annoyance effects. These may include:. Measuring air emissions from large open ponds can provide information for occupational and other environmental exposure estimates that can be compared to thresholds for human health or environmental effects. Information and data gaps include the relationship between particular drying technologies and the types and concentrations of particulates released, releases of solvents during extraction, likely concentrations of NH 3 in air during anaerobic digestion, and chemicals potentially released during pyrolysis.

That information would be submitted when the biorefineries seek air-quality permits. Species invasiveness is a concern unique to biofuels produced from algae and vascular plants. In addition, changing land use or altering landscapes to produce algal biofuel feedstocks can affect biodiversity. Effects of many biofuel feedstocks on biodiversity and mechanisms leading to those effects are beginning to be understood.

However, existing studies Fargione et al. Many cyanobacteria and eukaryotic microalgae are cosmopolitan in their spatial biogeographical distributions and therefore could not be invasive if released in regions included in their broad habitat range. However, they are not necessarily found in every location where their habitat requirements for example, pH, salinity, temperature, moisture, and climate are met, so their distribution is often mosaic-like Hoffmann, Other algae may be endemic to particular regions, for example, some cyanobacteria in Swedish lakes Rott and Hernandez-Marine, and particular marine species Hoffman, Endemic species could become invasive if transported elsewhere, but these species could also exist in low numbers in other locations even though they have not been recorded there.

Algae may have broader distributions than what has been recorded because of the lack of sampling on some continents especially of benthic habitats and because of the lack of detection of organisms at low densities Hoffmann, Coastal marine macroalgae tend to be less cosmopolitan in their spatial distribution than phytoplanktonic cyanobacteria and microalgae. Macroalgae have narrower temperature, light, substratum, and nutrient preferences. The wide range of processes that could transport microalgae away from open water also could contribute to their dispersal and consequentially to a broad distribution.

Vectors of algae include aquatic insects Stewart et al. The most important vectors of algae are birds Atkinson, ; Kristiansen, In one study of 16 species of waterfowl, 86 species of algae were found on the feet, 25 species on the feathers, and 25 species on the bills. Most algae survived out of surface waters for four hours, but most did not survive for more than eight hours Schlichting, Some species of algae may appear to be rare.

Whitford explains that species of freshwater algae may appear to be rare for several reasons for example, infrequent historical collections, species with long-lived spores that do not easily germinate, and species that are highly specific in their habitat requirements , but that very few freshwater species are actually rare. This suggests that few rare species of algae could be displaced by invasive algae used to produce biofuel feedstocks.

Releases of improved nongenetically engineered or genetically engineered strains of algae from biofuel production cultures to natural environments can be expected to be common, especially from open ponds. Releases may occur during the feedstock production stage or possibly during the harvesting or drying stages.


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Releases probably will occur most often through aerosolization, although leakages from ponds or weather-related spillage for example, high tides and heavy storms also are possible. The probability of release from an open pond would be related to pond area and freeboard space that is, the distance between normal water level and the top of the cultivation pond , the direction and speed of prevailing winds, the frequency and quantity of. Humidity affects the survival of unicellular algae Ehresmann and Hatch, Survival rates differ among algal groups. In one study climatic characteristics such as temperature, relative humidity, rainfall, wind velocity, and hours of sunshine affected the release and vertical transport of algae Sharma and Singh, Atmospheric density of algae is affected by aerosolization rate Sharma and Singh, , wind speed, and rainfall, as well as survival rate.

The abundance of algae in the atmosphere also depends on taxonomy of the algae. In one study, cyanobacteria had the highest density, whereas chlorophytes and diatoms were much less common Sharma and Singh, ; Wilkinson et al. Dissemination to distant sites can occur through the air, through water, and by boats Alexander, or animal vectors.

The wide range of vectors that could remove algae from open ponds include aquatic insects Stewart et al. Closed photobioreactor systems would have a much lower risk of release and transport of algae. Harvesting operations from open or closed systems could be a major potential route for loss of microalgae to the surrounding environment. If algae require culture media with characteristics substantially different from the surrounding natural environment especially if the algae have narrow tolerance limits to nutrients concentrations, pH, or salinity , then releases to the local landscape likely would result in low survival rates.

Survival rate would be further reduced if the cultured species is not tolerant of desiccation Hoffmann, Environmental concerns associated with releasing algae from biofuel facilities into natural waters include the potential for species invasiveness, alteration of nutrient recycling and trophic relationships, and the displacement of rare algal species.

Although some researchers and producers are considering the use of regionally native species that are adapted to the local climate Odlare et al. Some of the nonnative or improved species may be invasive in some environments. Invasive algae can compete with native species for light, space, or nutrients, and have different tolerances for stressors, compared to native species White and Shurin, Thus, invasive species can affect community composition and ecosystem processes Strayer et al. Successful invasions are characterized by the invasive potential of the invader and the invasibility of the native community Lonsdale, Species that are not invasive in one environment may be invasive when introduced to a different habitat Raghu et al.

For example, an algal species that thrives in saline waters may not survive or may invade freshwater ecosystems, even if released in a large quantity. Whether the ecological niches of invaders and the invaded community overlap is a predictor of success as well Mehnert et al. Whether a particular cultured algal species poses a threat as an invasive species to the surrounding aquatic environments needs to be considered. Some of the same characteristics that can make a species desirable as a biofuel feedstock, for example, rapid growth, vegetative propagation, pest resistance, and robustness in culture, also are those associated with invasiveness.

Possible but unlikely with appropriate controls Possible for nontarget species in cultures; low likelihood of blooms of nontarget species released to natural environments. Impossible unless accidental breach of photobioreactor Impossible unless accidental breach of photobioreactor.

Eutrophication Management and Ecotoxicology

Releases of some exotic algal species, particularly from open-pond cultures, could threaten the integrity of local and regional ecosystems Ryan, Blooms of exotic species could displace native species, with adverse impacts on organisms that feed on those species propagating through aquatic food webs. An example is the diatom Didymosphenia geminata also known as Didymo or Rock Snot that can cause dense algal blooms.

The blooms block sunlight and cause a local decline in native plant and animal life. Historically, D. The primary variable that is different among the pathways in Chapter 3 and would influence the likelihood of species invasions and changes in biodiversity is whether the pond system is open or closed Table Algal species known to be noninvasive or unlikely to cause harmful blooms could be selected for large-scale cultivation for fuels.

Invasiveness varies in different natural environments, and site-specific assessments might be necessary to reduce risks of invasion.

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Moreover, species that are intolerant of conditions in natural waters for example, salinity in the vicinity of the biofuel facility may be selected to minimize the risk of invasion if released. Landscape design also may be considered to limit any potential impacts of releases of algae from pond systems. Placing systems well away from waterways and wetlands where pond algae may thrive could reduce or minimize the likelihood of blooms of released species.

When considering the factors that affect the probability of release and the abundance of released organisms above, then mitigation measures might include shields from wind and mechanisms to discourage vectors.

1. Introduction

Indicators of sustainable ecological communities include metrics of aquatic diversity and invasiveness of algae. One category of such metrics would be diagnostic traits for invasiveness. Qualitative metrics that are related to invasiveness, but not necessarily diagnostic, include:. More direct metrics of aquatic biodiversity that relate to the sustainability of biofuels are recommended by McBride et al. These may include rare fish, aquatic invertebrates, or macrophytes. Additional sustainability indicators for aquatic biodiversity might include the types of metrics found in recovery plans for species protected under the Endangered Species Act Table Fish and Wildlife Service Recovery Plans.

Total population size Number of subpopulations Number of individuals in each subpopulation Trends in total population size Trends in number of subpopulations Trends in number of individuals in each subpopulation. The pattern of landscape conversion for any new infrastructure could affect terrestrial species and community diversity through at least three distinct mechanisms that also apply to algal biofuel production or other energy production McCabe, ; DOE, , a; Garvin et al.

The magnitude of land requirements discussed in Chapter 4 and the types of conversions discussed in section Land-Use Change in this chapter influence the magnitude of potential effects on ecological populations and communities. Displacement of native vegetation and individual vertebrates usually is limited to the area of the facility, but some species are sensitive to human infrastructure and tend to be displaced to distances beyond the boundaries of the facility, for example, female sage grouse avoiding nesting within meters of infrastructure associated with natural gas fields Holloran et al.

Extensive infrastructure, especially from multiple facilities, could fragment habitat for some wide-ranging vertebrates. Fragmentation of habitat is determined less by the area of a facility than by the dimensions compared to significant habitat types or corridors. One measure of fragmentation is the ratio of the perimeter patch edge length to the area of a habitat patch Dale and Pearson, Thus, a linear facility would tend to be fragmenting in more environments than one that is closer to square.

However, the latter configuration is more practical for system maintenance, so extensive linear facilities are not considered. Other potential measures of fragmentation include the percent of the landscape occupied by a given habitat, the number or density of habitat patches within a given area more patches means greater fragmentation , and the degree of connectedness or isolation among habitats McGarigal et al.

Even where habitat is not fragmented, human infrastructure and associated disturbance could reduce the habitat area beyond minimum levels required by certain species. Carlsen et al. They found that few studies examined behavioral or population dynamics associated with large areas of contiguous habitat, which also contained smaller patches of unsuitable or disturbed lands as in algal biofuel development or oil and gas development. An exception is a theoretical study of American badger at an oil production site that investigated the effects of increasing areas of patches of disturbance on an otherwise highly suitable matrix of tallgrass prairie in Oklahoma Jager et al.

Critical disturbance areas would depend on the species of concern, the habitat type, habitat suitability, and type of infrastructure. Impacts on terrestrial vegetation and wildlife could vary widely, depending on the specific sites chosen and the land-use baseline and dynamics prevailing in the absence of algae cultivation and algal biofuel refineries.

According to Wigmosta et al. As discussed in Chapter 4 , the most favorable conditions in terms of land and water requirements were in the Gulf Coast region. Shrub-scrub habitat in the United States is widely distributed but is threatened by changes in land-use patterns; numerous bird species dependent on this habitat type are in decline NRCS and WHC, Development of large areas of shrub-scrub for ponds, up to , square kilometers using figures from Wigmosta et al. The presence and abundance of wildlife need to be assessed prior to construction, as is done for facilities that are subject to environmental assessment DOE, a.

Landscape design could minimize potential effects on biodiversity. Dale et al. In planning the size of individual ponds, their density on the landscape, and associated production facilities, managers would have to consider potential environmental impacts on biodiversity. Open algal ponds may be sources of water to wildlife that may prove beneficial in arid conditions or harmful if toxic to certain species. The risks of animals being exposed to salinity or chemicals in water from algae cultivation ponds and having adverse effects from drinking or dermal exposures are unknown.

Toxicity from salt exposure is possible. This occurs when salt or chloride are accumulated in blood at toxic levels and, in the case of birds, at rates too high to be excreted by salt glands. For example, mortality from sodium toxicity has been observed at hypersaline playa lakes of southeast New Mexico Meteyer et al. However, the water for algae cultivation is not likely to be hypersaline.

Coastal bird species have specialized organs to accommodate high salt levels Hughes, Lethal and sublethal salinity concentrations for some species are summarized in a U. Department of the Interior report , with toxicity threshold values for ducks ranging from 9 to 20 parts per thousand compared to the salinity of most seawater at 35 parts per thousand. Many chemical and behavioral factors could influence exposure of wildlife to salt and other chemicals in open-pond systems.

For example, artificial water developments in desert environments are sometimes an important water source for local bird populations Lynn et al. If ponds are sited near wastewater treatment facilities and CO 2 sources that is, near population centers , then water is unlikely to be rare in the landscape and wildlife will have many options for water sources.

Ponds with dense algae might not be as attractive to wildlife as more pristine. Similarly, the effect of dense algae on the attractiveness of ponds for wildlife drinking is unknown. For oil-field wastewater evaporation ponds, bird exposures appear to be episodic, coinciding with migration behavior Ramirez, To consider potential exposures of wildlife to toxicants in culture water from algal biofuel facilities and their potential effects, analogies may be made to agricultural evaporation ponds and oil-field wastewater evaporation ponds.

In the western part of the San Joaquin Valley, California, agricultural evaporation ponds have been developed where other options for disposal of drainage water are limited. Birds use evaporation ponds for resting, foraging, and nesting Evaporation Ponds Technical Committee, In another study, northern pintails Anas acuta wintering in Tulare Basin, CA, were found not to use or select agricultural drain-water evaporation ponds or sewage treatment ponds which might appear similar to some algal biofuel ponds and to prefer flooded fields and marshes Fleskes et al. For agricultural evaporation ponds, the primary wildlife concern has been the concentration of selenium Evaporation Ponds Technical Committee, ; its environmental transformations and accumulation have been studied Gao et al.

Whether selenium might represent a significant exposure in algal ponds depends on the availability of selenium in source water and in underlying soils if pond water seeps out. Some investigators suggest that waterfowl exposed to waters from agricultural evaporation ponds might be at risk from uranium toxicity Duff et al. Uranium accumulation in pond sediments was attributed in part to decaying algae. Arsenic dynamics also have been studied as a potential concern Ryu et al.

In another potentially analogous example, birds Ramirez, , as well as bats, amphibians, reptiles, small mammals, game species, and insects Ramirez, , have been observed to be attracted to large 0. Bird fatalities from those ponds generally are attributed to oil, but sodium toxicity and surfactants have been implicated in some cases Ramirez, Attraction to algal ponds could be a major problem if they contain toxic chemicals or pathogens at harmful concentrations.

Fish injuries ada, and bird fatalities Osborn et al. Adaptive management can play a role in mitigating any adverse effects on wildlife through exposure via drinking. The committee is not aware of any reports of wildlife drinking being a concern in existing open-pond algae cultivation facilities. As the number and size of facilities increase, concentrations of potential toxicants in water and wildlife drinking exposure needs to be monitored to ensure that the latter is not a concern. The fail-safe mitigation for wildlife exposure to salinity or any toxicants in culture waters is to use closed photobioreactor systems.

Moreover, salinity concerns would be eliminated through the use of fresh water, though Chapter 4 discusses resource constraints for fresh water at commercial scales of development. Mitigations for open-pond systems might include netting to prevent exposure as in the oilfield wastewater evaporation ponds , but this would be expensive and only necessary if wildlife exposure proves to be a problem. Rapid stirring could make ponds less suitable as wildlife drinking habitat than still water.

Other wildlife deterrents may be. Displacement of vegetation and vertebrates habitat loss , possible fragmentation of habitat. Displacement of vegetation and vertebrates habitat loss , possible fragmentation of habitat, probably at a smaller spatial scale than for other pathways. Some of the mitigations used for oilfield wastewater evaporation ponds, such as covering the surface with plastic balls to make the ponds less attractive to birds Ramirez, , are not options for photosynthetic fuel sources.

Similarly, mitigation strategies used in agricultural evaporation ponds, such as steepening pond slopes or maintaining deep water levels that reduce suitability of bird feeding habitat, are not practical for algae cultivation that requires shallow ponds Evaporation Ponds Technical Committee, As open ponds are monitored for chemical contaminants, toxicity thresholds for these chemicals will help determine when culture waters need to be disposed and renewed.

As with land-use change, regarding the landscape pattern of development, the primary relevant difference among the pathways in Chapter 3 is the difference between the land required for open-pond and photobioreactor systems see Chapter 4. For wildlife drinking, the primary variable of interest is closed versus open systems Table Metrics of terrestrial biodiversity for the sustainability of biofuels that are recommended by McBride et al.

Habitat area can be a proxy for population size Turlure et al. As with aquatic diversity metrics, additional sustainability indicators for terrestrial biodiversity might be obtained from recovery plans for species listed under the Endangered Species Act Table For wildlife exposures to salinity and contaminants in drinking water, sustainability indicators would include:.

Patterns of development of algal biofuel facilities in relation to wildlife corridors have not been studied because locations for future development are uncertain. The spatial scale and landscape pattern of these developments needs to be understood to simulate the effects on wildlife populations. As algae cultivation expands in number and scale, the potential for wildlife drinking needs to be assessed at sites.


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If wildlife drinking is observed, then concentrations of toxicants in source waters and culture waters need to be measured to ensure that there is no threat to wildlife health. Alternatively, measures to deter wildlife drinking can be implemented. The environmental sustainability of genetically engineered feedstocks for bioenergy Wolt, ; Moon et al. Some algal biofuel companies, such as Algenol and Synthetic Genomics, are conducting research on genetically engineered organisms for algal biofuel production Gressel, In a hypothetical, worst-case scenario, genetically engineered algae that have been introduced to natural environments might persist and become so abundant that they create harmful algal blooms Snow and Smith, Clearly, any adverse effects of released genetically engineered algae, if observed, would affect the sustainable development of algal biofuel technologies.

The evaluation of potential effects of genetically engineered algae will be a complex undertaking, given the diversity of organisms, range of engineered functions, and range of environments potentially receiving the engineered organisms Tiedje et al. This section of the report addresses the novel traits and genetic structure of genetically engineered cyanobacteria and microalgae for biofuels and whether they have unique or more uncertain risks. Potential genetic manipulation methods are discussed in Chapter 2. Past broad assessments of the risks of genetically engineered organisms have concluded that the product novel traits is more important than the process genetic engineering techniques for evaluating risk NRC, ; Tiedje et al.

However, novel traits may be more common when the process for creating new algae involves direct genetic manipulation than when horizontal gene transfer occurs in evolutionary time. Several traits of algae for biofuels may be modified through genetic engineering methods.

Most are intended to increase biomass or oil productivity, though some could be designed to minimize survival or reproduction following release. Increasing productivity could involve objectives such as enhancing lipid content as a precursor to biodiesel which could involve growing cells in nitrogen-deficient or silicon-deficient media , introducing biological pathways that permit direct production of fuels that need minimal processing prior to distribution and use, modifying cells to secrete feedstock or fuel directly into the culture medium, modifying carbohydrate metabolism in cells increasing glucan storage, decreasing starch degradation , increasing tolerance to stressors such as salt, light, pH, temperature, glyphosate Radakovits et al.

Some of these engineered traits and intended or unintended accompanying traits could affect either the suitability of algae for biofuel production purposes or their survival and physiology when released into natural systems. Predictors of potential adverse effects of genetically engineered algae include probability of release, abundance of organisms released predictor of establishment , survival rate and fitness, reproduction rate, probability of dissemination to distant sites, interactions with other organisms, probability of genetic exchange, and probability of an adverse effect Alexander, New traits potentially can influence these factors, but few of these relationships are understood.

Cell density in the culture medium could be affected by engineered traits. The scale and frequency of releases might determine whether the release leads to a self-sustaining established population Tiedje et al. The survival rate of a genetically engineered microalga or cyanobacterium will be determined by a combination of the species identity, the genetic modification s , and the environment to which it is released.

Algae with high lipid content probably will be more attractive to predators. Some researchers suggest that most genetically engineered organisms will have lower fitness in receiving environments than unmodified organisms Tiedje et al. Algae could be cross-bred or engineered to have high growth rates under specific culture conditions, and some of these might have high growth rates under specific natural conditions.

New traits conferred on algae by genetic modifications would determine whether and how community interactions might be altered. Radakovits et al. Genetic exchange might lead to unexpected effects. Snow et al. The three types of horizontal transfer are transformation of free deoxyribonucleic acid DNA , conjugation, and transduction.

The transfer of genes between microorganisms is common in some species Snow et al. About 1 to 20 percent of the genomes of bacteria consist of DNA acquired recently in an evolutionary context , predominantly from other prokaryotes but also from eukaryotes, for example, metazoa Ochman et al. Research keywords: Aboriginal land management; wildlife conservation and management; disease ecology; protected areas; linking local and traditional knowledge with science; human-wildlife conflicts; youth experiential education; vegetation-permafrost interactions.

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