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. (2011), within the land area potentially suitable for biofuels, land cover types consisted of 42 percent shrub or scrub, 19 percent herbaceous, 14 percent evergreen forest, 10 percent pastureland, 8 percent deciduous forest, and 7 percent other lands including mixed forest, barren, and low-intensity developed. 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, 2007). Development of large areas of shrub-scrub for ponds, up to 181,000 square kilometers (using figures from Wigmosta et al., 2011), could accelerate this decline.
18.104.22.168. Opportunities for Mitigation
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, 2010a). Landscape design could minimize potential effects on biodiversity. Dale et al. (2011) suggest that incorporating design considerations recommended for bioenergy could prevent or minimize adverse effects on terrestrial biodiversity, for example by maintaining corridors for movement of terrestrial wildlife. 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.
5.7.2 Wildlife Drinking
22.214.171.124 Potential Environmental Effects
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., 1997). However, the water for algae cultivation is not likely to be hypersaline. Coastal bird species have specialized organs to accommodate high salt levels (Hughes, 2003). Lethal and sublethal salinity concentrations for some species are summarized in a U.S. Department of the Interior report (1998), 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., 2006), but can be less important for some migratory species (Lynn et al., 2006) or animals that may have a strong fidelity for specific water sources (Dickens et al., 2009). If ponds are sited near wastewater treatment facilities and CO2 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