An unusual trophic subsidy and species dominance in a tropical stream

In classical theory, species are assumed to achieve dominance through competitive exclusion, but if food resources are limiting, cross-habitat trophic subsidies could also underpin dominance. The impact of dominant species on community dynamics may depend on the energy base of population size. We report on an unusual, spatially subsidized population of a tropical, stream-dwelling crab that dominates the benthic fauna of a Kenyan stream. Diet and stable isotope analyses indicated that this crab is a true omnivore, with terrestrial subsidies dominating both plant and animal resources. Unusually, the animal prey included almost no aquatic invertebrates. Instead, a single species of ant constituted approximately 35% of the annual diet (stomach contents analysis) and up to 90% of assimilated nitrogen (estimates from stable isotope analysis). Ants may be pivotal to enabling crab dominance, and this crab may be largely disconnected from the local trophic network for its dietary needs. The paucity of other invertebrates in the stream community suggests that this super-dominant crab is a strong interactor that suppresses aquatic invertebrate populations. Common stabilizing attributes of spatially subsidized food webs (e.g., asynchronous prey availability, wide feeding niche, consumer migration) were absent from this system, and although apparently stable, it may be vulnerable to disturbance in the donor habitat.     

Strategic alignment with organizational priorities and work engagement: A multi‐wave analysis

This study advances the limited research on work alignment and work engagement by investigating how perceived alignment of job tasks and organizational strategic priorities (strategic alignment) influences work engagement. Measures of job control and work social support were also included to enable comparisons between strategic alignment and other well‐established job resources. A total of 1011 employees of an Australian state police service responded to three electronic, self‐report surveys. A reciprocal model was assessed over three waves of data, with varying time lags: 18 (Time 1 to Time 2), 12 (Time 2 to Time 3), and 30 months (Time 1 to Time 3). Longitudinal, reciprocal relationships were observed for work engagement and job control, strategic alignment, and colleague support. Work engagement also predicted supervisor support over time (reverse effect). This study demonstrated that, in addition to job resources, perceived alignment of job tasks and organizational priorities plays an important role in maintaining high levels of work engagement over time. Copyright © 2013 John Wiley & Sons, Ltd.     

Are soils beneath coniferous tree stands more acidic than soils beneath deciduous tree stands?

Environmental Science and Pollution Research - In 2008, the Mulberry River, a National Wild and Scenic River, was listed as impaired due to low pH (below pH 6.0). Over the last...     

Policy diffusion in arid Basin water management: a Q method approach in the Murray–Darling Basin,Australia

The Murray–Darling Basin is Australia’s national food bowl, home to almost half of the national income from food production, as well as internationally significant wetlands, iconic red gum forests, endangered flora and fauna, and approximately 40 autonomous indigenous nations. Persistent severe drought and extreme flooding episodes have presented new challenges in the region. Chief among these challenges is the establishment of a legitimate framework to sustainably manage water resources that finds common ground between environmental, indigenous and commercial interests. A powerful approach to examine these processes is through the theory of diffusion and adaptation of policy innovations. Here, we describe an approach to place this theory on empirical ground using Q methodology. We elucidate patterns of subjectivity, to explore the perceptions of expert advice, subsidiarity and local knowledge to better understand the interests in play. We find that respect is held for local practitioners (water managers and farmers) and indigenous knowledge, but while policy innovations are being generated, the diffusion of policy is contested. We identify the potential, though limited, for common ground through substantive and respectful consultation.     

Compatibility of booster seats and vehicles in the U.S. market

Objective: The objective of this study was to analyze booster and rear vehicle seat dimensions to identify the most frequent compatibility problems.

Methods: Measurements were collected from 40 high-back and backless boosters and 95 left rear and center rear row seating positions in 50 modern vehicles. Dimensions were compared for 3,800 booster/vehicle seat combinations. For validation and estimation of tolerance and correction factors, 72 booster installations were physically completed and compared with measurement-based compatibility predictions. Dimensions were also compared to the International Organization for Standardization (ISO) volumetric envelopes of forward-facing child restraints and boosters.

Results: Seat belt buckles in outboard positions accommodated the width of boosters better than center positions (success rates of 85.4 and 34.7%, respectively). Adequate head restraint clearance occurred in 71.9 to 77.2% of combinations, depending on the booster's head support setting. Booster recline angles aligned properly with vehicle seat cushion angles in 71.5% of combinations. In cases of poor angle alignment, booster angles were more obtuse than the vehicle seat angles 97.7% of the time. Head restraint interference exacerbated angle alignment issues. Data indicate success rates above 90% for boosters being fully supported by the length of the seat cushion and for adequate height clearance with the vehicle roofline. Comparison to ISO envelopes indicates that most boosters on the U.S. market are taller and angled more obtusely than ISO target envelopes.

Conclusions: This study quantifies some of the common interferences between boosters and vehicles that may complicate booster usage. Data are useful for design and to prioritize specific problem areas.     

The effects of elevated carbon dioxide levels on a Vibrio sp. isolated from the deep-sea

Introduction

The effect of oceanic CO₂ sequestration was examined exposing a deep-sea bacterium identified as Vibrio alginolyticus (9NA) to elevated levels of carbon dioxide and monitoring its growth at 2,750 psi (1,846 m depth).

Findings

The wild-type strain of 9NA could not grow in acidified marine broth below a pH of 5. The pH of marine broth did not drop below this level until at least 20.8 mM of CO₂ was injected into the medium. 9NA did not grow at this CO₂ concentration or higher concentrations (31.2 and 41.6 mM) for at least 72 h. Carbon dioxide at 10.4 mM also inhibited growth, but the bacterium was able to recover and grow. Exposure to CO₂ caused the cell to undergo a morphological change and form a dimple-like structure. The membrane was also damaged but with no protein leakage.     

Windsor, Ontario exposure assessment study: design and methods validation of personal, indoor, and outdoor air pollution monitoring

The Windsor, Ontario Exposure Assessment Study evaluated the contribution of ambient air pollutants to personal and indoor exposures of adults and asthmatic children living in Windsor, Ontario, Canada. In addition, the role of personal, indoor, and outdoor air pollution exposures upon asthmatic children's respiratory health was assessed. Several active and passive sampling methods were applied, or adapted, for personal, indoor, and outdoor residential monitoring of nitrogen dioxide, volatile organic compounds, particulate matter (PM; PM < or = 2.5 microm [PM2.5] and < or = 10 microm [PM10] in aerodynamic diameter), elemental carbon, ultrafine particles, ozone, air exchange rates, allergens in settled dust, and particulate-associated metals. Participants completed five consecutive days of monitoring during the winter and summer of 2005 and 2006. During 2006, in addition to undertaking the air pollution measurements, asthmatic children completed respiratory health measurements (including peak flow meter tests and exhaled breath condensate) and tracked respiratory symptoms in a diary. Extensive quality assurance and quality control steps were implemented, including the collocation of instruments at the National Air Pollution Surveillance site operated by Environment Canada and at the Michigan Department of Environmental Quality site in Allen Park, Detroit, MI. During field sampling, duplicate and blank samples were also completed and these data are reported. In total, 50 adults and 51 asthmatic children were recruited to participate, resulting in 922 participant days of data. When comparing the methods used in the study with standard reference methods, field blanks were low and bias was acceptable, with most methods being within 20% of reference methods. Duplicates were typically within less than 10% of each other, indicating that study results can be used with confidence. This paper covers study design, recruitment, methodology, time activity diary, surveys, and quality assurance and control results for the different methods used.     

Status and trends of terrestrial arthropod abundance and diversity in the North Atlantic region of the Arctic

Ambio - The Circumpolar Biodiversity Monitoring Programme (CBMP) provides an opportunity to improve our knowledge of Arctic arthropod diversity, but initial baseline studies are required to...     

Using cumulative human-impact models to reveal global threat patterns for seahorses

Understanding threats acting on marine organisms and their conservation status is vital but challenging given a paucity of data. We studied the cumulative human impact (CHI) on and conservation status of seahorses (Hippocampus spp.)—a genus of rare and data-poor marine fishes. With expert knowledge and relevant spatial data sets, we built linear-additive models to assess and map the CHI of 12 anthropogenic stressors on 42 seahorse species. We examined the utility of indices of estimated impact (impact of each stressor and CHI) in predicting conservation status for species with random forest (RF) models. The CHI values for threatened species were significantly higher than those for nonthreatened species (category based on International Union for Conservation of Nature Red List). We derived high-accuracy RF models (87% and 96%) that predicted that 5 of the 17 data-deficient species were threatened. Demersal fishing practices with high bycatch and pollution were the best predictors of threat category. Major threat epicenters were in China, Southeast Asia, and Europe. Our results and maps of CHI may help guide global seahorse conservation and indicate that modeling and mapping human impacts can reveal threat patterns and conservation status for data-poor species. We found that for exploring threat patterns of focal species, species-level CHI models are better than existing ecosystem-level CHI models.