of some cultivation systems would provide refuges from visual predators (Jacob et al., 2008; Jackson et al., 2009). Fewer mosquito species can tolerate saline conditions than fresh water (Patrick and Bradley, 2000), but some species can tolerate salinities of 100 percent sea water (Grueber and Bradley, 1994).

Providing habitat for mosquitoes could be a concern for human health and the acceptability of algal biofuel production for several reasons including:

•   Mosquitoes are considered a pest and a nuisance that may not be tolerated by people living near a cultivation facility. Communities near proposed constructed wetland sites sometimes object to siting based on the anticipation of a mosquito problem (Anderson et al., 2007).

•   Mosquitoes are vectors for numerous human infectious diseases in the United States, such as Eastern equine encephalitis, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, Western equine encephalitis, and Dengue fever (recently reported in Florida). West Nile virus is also hypothesized to be a factor in the decline of sage grouse (Naugle et al., 2004).

•   If the ponds for algae cultivation become breeding grounds for mosquitoes, there is a risk that the larvae will become a pest, reducing algal population densities below economically productive levels through predation.

5.11.2 Opportunities for Mitigation

Measures could be taken to control mosquito and other pest populations in and around algae cultivation ponds. The extensive use of agitators, aerators, and fountains decrease the suitability of open ponds for mosquito habitat (Jackson et al., 2009) and distribute nutrients and algae in the system. If standing water at cultivation facilities is minimized, mosquitoes and associated health effects should not be a problem.

Other mitigation options include site-specific surveys that can inform mosquito management agencies regarding the timing, species, and abundance of mosquitoes to develop disease-reduction plans (Anderson et al., 2007). Control options include chemical treatments like insecticides and biological methods such as the introduction of natural predators such as mosquitofish that consume mosquito larvae. If some of these measures are used without prior consultation and acceptance by the public, or if it is perceived that a population control method poses a threat to the human health or well-being, local communities might not accept algae production as a viable source of energy.

5.11.3 Sustainability Indicators

The sustainability indicators for mosquito-borne diseases are density of mosquito larvae in ponds and changes in incidence of mosquito-borne diseases attributable to cultivation ponds.

5.12 CONCLUSIONS

Reducing GHG emissions from the transportation sector has been one of the primary motivations for using alternative liquid transportation fuels. Therefore, the life-cycle GHG emissions are key factors in considering the sustainable development of algal biofuels. Published estimates of GHG emissions span a wide range, with some studies suggesting that algal biofuel production has high GHG emissions. The utility of these LCAs is that they point out key drivers of CO2 emissions in the algal biofuel supply chains and indicate



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