Impact of host community composition on Lyme disease risk

The drivers of variable disease risk in complex multi-host disease systems have proved very difficult to identify. Here we test a model that explains the entomological risk of Lyme disease (LD) in terms of host community composition. The model was parameterized in a continuous forest tract at the Cary Institute of Ecosystem Studies (formerly the Institute of Ecosystem Studies) in New York State, U.S.A. We report the results of continuing longitudinal observations (10 years) at the Cary Institute, and of a shorter-term study conducted in forest fragments in LD endemic areas of Connecticut, New Jersey, and New York, USA. Model predictions were significantly correlated with the observed nymphal infection prevalence (NIP) in both studies, although the relationship was stronger in the longer-term Cary Institute study. Species richness was negatively, albeit weakly, correlated with NIP (logistic regression), and there was no relationship between the Shannon diversity index (H') and NIP. Although these results suggest that LD risk is in fact dependent on host diversity, the relationship relies explicitly on the identities and frequencies of host species such that conventional uses of the term biodiversity (i.e., richness, evenness, H') are less appropriate than are metrics that include species identity. This underscores the importance of constructing interaction webs for vertebrates and exploring the direct and indirect effects of anthropogenic stressors on host community composition.     

What’s Wrong with the Tap? Examining Perceptions of Tap Water and Bottled Water at Purdue University

The environmental impacts of bottled water prompted us to explore drinking water choices at Purdue University, located in West Lafayette, IN. A random sample of 2,045 Purdue University students, staff, and faculty was invited to participate in an online survey. The survey assessed current behaviors as well as perceived barriers and benefits to drinking tap water versus bottled water. 677 surveys were completed for a response rate of 33.1%. We then conducted qualitative interviews with a purposive sample of university undergraduates (n = 21) to obtain contextual insights into the survey results and the beliefs of individuals with a variety of drinking water preferences. This study revealed that women drink disproportionately more bottled water then men while undergraduate students drink more than graduate students, staff and faculty. The study also uncovered a widespread belief that recycling eliminates the environmental impacts of bottled water. Important barriers to drinking tap water at Purdue include: perceived risks from tap water and the perceived safety of bottled water, preferring the taste of bottled water, and the convenience of drinking bottled water. The qualitative interviews revealed that drinking water choices can be influenced by several factors—especially whether individuals trust tap water to be clean—but involve varying levels of complexity. The implications of these results for social marketing strategies to promote tap water are discussed.     

Range-wide effects of breeding- and nonbreeding-season climate on the abundance of a Neotropical migrant songbird

Geographic variation in the population dynamics of a species can result from regional variability in climate and how it affects reproduction and survival. Identifying such effects for migratory birds requires the integration of population models with knowledge of migratory connectivity between breeding and nonbreeding areas. We used Bayesian hierarchical models with 26 years of Breeding Bird Survey data (1982-2007) to investigate the impacts of breeding- and nonbreeding-season climate on abundance of American Redstarts (Setophaga ruticilla) across the species range. We focused on 15 populations defined by Bird Conservation Regions, and we included variation across routes and observers as well as temporal trends and climate effects. American Redstart populations that breed in eastern North America showed increased abundance following winters with higher plant productivity in the Caribbean where they are expected to overwinter. In contrast, western breeding populations showed little response to conditions in their expected wintering areas in west Mexico, perhaps reflecting lower migratory connectivity or differential effects of winter rainfall on individuals across the species range. Unlike the case with winter climate, we found few effects of temperature prior to arrival in spring (March-April) or during the nesting period (May-June) on abundance the following year. Eight populations showed significant changes in abundance, with the steepest declines in the Atlantic Northern Forest (-3.4%/yr) and the greatest increases in the Prairie Hardwood Transition (4%/yr). This study emphasizes how the effects of climate on populations of migratory birds are context dependent and can vary depending on geographic location and the period of the annual cycle. Such knowledge is essential for predicting regional variation in how populations of a species might vary in their response to climate change.     

Corrections for measurements of tritium in subterranean vapor using silica gel

Hazardous contaminants buried within vadose zones can accumulate in soil gas. The concentrations and spatial extent of these contaminants are measured to evaluate potential transport to groundwater for public risk evaluation. Tritium is an important contaminant found and monitored for in vadose zones across numerous sites within the US nuclear weapons complex, including Los Alamos National Laboratory. The extraction, collection, and laboratory analysis of tritium from subterranean soil gas presents numerous technical challenges that have not been fully studied. Particularly, the lack of moisture in the soil gas in the vadose zone makes it difficult to obtain enough sample (e.g., >5 g) to provide for the required measurement sensitivity, and often, only small amounts of moisture can be collected. Further, although silica gel has high affinity for water vapor and is prebaked prior to sampling, there is still sufficient residual moisture in the prebaked gel to dilute the relatively small amount of sampled moisture; thereby, significantly lowering the ??true?? tritium concentration in the soil gas. This paper provides an evaluation of the magnitude of the bias from dilution, provides methods to correct past measurements by applying a correction factor (CF), and evaluates the uncertainty of the CF values. For this, 10,000 Monte Carlo calculations were performed, and distribution parameters of CF values were determined and evaluated. The mean and standard deviation of the distribution of CF values were 1.53 ± 0.36, and the minimum, median, and maximum values were 1.14, 1.43, and 5.27, respectively.     

Sustainable local land use policy: rhetoric and reality

Abstract

This study examined trends in population redistribution and residential land use changes in northeast Scotland during 1988 to 2003. We utilised a geographical information system (GIS) tool to bring together data from interrelated sources and to analyse population settlement and land use changes at detailed spatial scale. This analysis revealed that substantial land conversion had taken place in the region; particularly conversion of agricultural lands to built-up and residential areas. It also drew attention to policy conflicts, discrepancies between policy rhetoric and policy implementations. More specifically, it was shown that substantial farm land conversion had taken place in suburban areas and rural Aberdeenshire with little change in the size of derelict land in Aberdeen City. The reason given for this was that it was costly to rehabilitate and reuse derelict lands and this conflicted with the objective of providing affordable housing in the City region. The implication of this study is that if the declared policy objectives of integrated and sustainable land use and transport policies are to be achieved, then local authorities may need to cooperate to minimise conflicts between economic and environmental objectives.