Enhanced dichloroethene biodegradation in fractured rock under biostimulated and bioaugmented conditions

Significant microbial reductive dechlorination of [1,2 ¹⁴C] cis‐dichloroethene (DCE) was observed in anoxic microcosms prepared with unamended, fractured rock aquifer materials, which were colonized in situ at multiple depths in two boreholes at the Naval Air Warfare Center (NAWC) in West Trenton, New Jersey. The lack of significant reductive dechlorination in corresponding water‐only treatments indicated that chlororespiration activity in unamended, fractured rock treatments was primarily associated with colonized core material. In these unamended fractured rock microcosms, activity was highest in the shallow zones and generally decreased with increasing depth. Electron‐donor amendment (biostimulation) enhanced chlororespiration in some but not all treatments. In contrast, combining electron‐donor amendment with KB1 amendment (bioaugmentation) enhanced chlororespiration in all treatments and substantially reduced the variability in chlororespiration activity both within and between treatments. These results indicate (1) that a potential for chlororespiration‐based bioremediation exists at NAWC Trenton but is limited under nonengineered conditions, (2) that the limitation on chlororespiration activity is not entirely due to electron‐donor availability, and (3) that a bioaugmentation approach can substantially enhance in situ bioremediation if the requisite amendments can be adequately distributed throughout the fractured rock matrix. © 2012 Wiley Periodicals, Inc.*     

Forest products and traditional peoples: Economic, biological, and cultural considerations

Conservationists and environmental economists have promoted the extraction of non–timber forest products (NTFP) as an alternative to forest conversion and as a means to benefit forest peoples. This article discusses the development of NTFP economic analyses and some economic, biological and socio–cultural constraints on the use of forest resources and methodological limitations of NTFP investigations. Several case studies document the importance of the forest in both North and South America. While studies differ in their conclusions regarding the sustainability of NTFP extraction, most researchers agree that sustainable harvesting is rare. The article argues for additional considerations that transcend the biological and economic concerns. While forests provide the basis of material culture for peoples that inhabit them, they are also linked intrinsically to the religion, mythology, and psyche of native peoples. Conservationists have an ethical obligation to consider the needs and desires of these people in conjunction with conservation and management plans.     

NARAC: an emergency response resource for predicting the atmospheric dispersion and assessing the consequences of airborne radionuclides

The National Atmospheric Release Advisory Center (NARAC) serves as a national resource for the United States, providing tools and services to quickly predict the environmental contamination and health effects caused by airborne radionuclides, and to provide scientifically based guidance to emergency managers for the protection of human life. NARAC's scientists have developed a diverse tool kit of numerical modeling capabilities to respond to different types of release events, distance scales (local, regional, continental, and global), and response times.     

Using design effects from previous cluster surveys to guide sample size calculation in emergency settings

A good estimate of the design effect is critical for calculating the most efficient sample size for cluster surveys. We reviewed the design effects for seven nutrition and health outcomes from nine population-based cluster surveys conducted in emergency settings. Most of the design effects for outcomes in children, and one-half of the design effects for crude mortality, were below two. A reassessment of mortality data from Kosovo and Badghis, Afghanistan revealed that, given the same number of clusters, changing sample size had a relatively small impact on the precision of the estimate of mortality. We concluded that, in most surveys, assuming a design effect of 1.5 for acute malnutrition in children and two or less for crude mortality would produce a more efficient sample size. In addition, enhancing the sample size in cluster surveys without increasing the number of clusters may not result in substantial improvements in precision.     

Exploited species impacts on trophic linkages along reef-seagrass interfaces in the Florida Keys

The removal of fish biomass by extensive commercial and recreational fishing has been hypothesized to drastically alter the strength of trophic linkages among adjacent habitats. We evaluated the effects of removing predatory fishes on trophic transfers between coral reefs and adjacent seagrass meadows by comparing fish community structure, grazing intensity, and invertebrate predation potential in predator-rich no-take sites and nearby predator-poor fished sites in the Florida Keys (USA). Exploited fishes were more abundant at the no-take sites than at the fished sites. Most of the exploited fishes were either omnivores or invertivores. More piscivores were recorded at no-take sites, but most (approximately 95%) were moderately fished and unexploited species (barracuda and bar jacks, respectively). Impacts of these consumers on lower trophic levels were modest. Herbivorous and smaller prey fish (< 10 cm total length) densities and seagrass grazing diminished with distance from reefs and were not negatively impacted by the elevated densities of exploited fishes at no-take sites. Predation by reef fishes on most tethered invertebrates was high, but exploited species impacts varied with prey type. The results of the study show that, even though abundances of reef-associated fishes have been reduced at fished sites, there is little evidence that this has produced cascading trophic effects or interrupted cross-habitat energy exchanges between coral reefs and seagrasses.     

Genus-specific associations of marine sponges with group I crenarchaeotes

Sponges have rich and diverse associated microbial communities, which may have important functions in their metabolism. A survey of the archaeal communities of 23 poriferan species, focusing on the family Axinellidae, was conducted over the period 2002–2004 using 16S rDNA gene libraries created with archaeal-specific primers. The 28S rDNA sequences of the sponge hosts were also obtained. Of 23 species, 19 showed evidence of archaeal communities from group C1a (marine group I; Crenarchaeota), with three of these also showing evidence of Archaea from group E2 (marine group II; Euryarchaeota). Within the Crenarchaeota, two strongly supported sponge-specific clades were identified corresponding to the sponge family Axinellidae, and a novel sponge clade denoted clade C. These findings suggest that these archaea have evolved closely with their sponge hosts and are likely to play an important role in their metabolism.

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Species diversity modulates predation

Predation occurs in a context defined by both prey and non-prey species. At present it is largely unknown how species diversity in general, and species that are not included in a predator's diet in particular, modify predator-prey interactions. Therefore we studied how both the density and diversity of non-prey species modified predation rates in experimental microcosms. We found that even a low density of a single nonprey species depressed the asymptote of a predator's functional response. Increases in the density and diversity of non-prey species further reduced predation rates to very low levels. Controls showed that this diversity effect was not due to the identity of any of the non-prey species. Our results establish that both the density and diversity of species outside a predator's diet can significantly weaken the strength of predator-prey interactions. These results have major implications for ecological theory on species interactions in simple vs. complex communities. We discuss our findings in terms of the relationship between diversity and stability.