Wildlife corridors as a connected subgraph problem

Wildlife corridors connect areas of biological significance to mitigate the negative ecological impacts of habitat fragmentation. In this article we formalize the optimal corridor design as a connected subgraph problem, which maximizes the amount of suitable habitat in a fully connected parcel network linking core habitat areas, subject to a constraint on the funds available for land acquisition. To solve this challenging computational problem, we propose a hybrid approach that combines graph algorithms with Mixed Integer Programming-based optimization. We apply this technique to the design of corridors for grizzly bears in the U.S. Northern Rockies, illustrating the underlying computational complexities by varying the granularity of the parcels available for acquisition. The approach that is introduced is general and can be applied to other species or other similar problems, such as those occurring in social networks.     

Microbial indicators of heavy metal contamination in urban and rural soils

Urban soils and especially their microbiology have been a neglected area of study. In this paper, we report on microbial properties of urban soils compared to rural soils of similar lithogenic origin in the vicinity of Aberdeen city. Significant differences in basal respiration rates, microbial biomass and ecophysiological parameters were found in urban soils compared to rural soils. Analysis of community level physiological profiles (CLPP) of micro-organisms showed they consumed C sources faster in urban soils to maintain the same level activity as those in rural soils. Cu, Pb, Zn and Ni were the principal elements that had accumulated in urban soils compared with their rural counterparts with Pb being the most significant metal to distinguish urban soils from rural soils. Sequential extraction showed the final residue after extraction was normally the highest proportion except for Pb, for which the hydroxylamine-hydrochloride extractable Pb was the largest part. Acetic acid extractable fraction of Cd, Cu, Ni, Pb and Zn were higher in urban soils and aqua regia extractable fraction were lower suggesting an elevated availability of heavy metals in urban soils. Correlation analyses between different microbial indicators (basal respiration, biomass-C, and sole C source tests) and heavy metal fractions indicated that basal respiration was negatively correlated with soil Cd, Cu, Ni and Zn inputs while soil microbial biomass was only significantly correlated with Pb. However, both exchangeable and iron- and manganese-bound Ni fractions were mostly responsible for shift of the soil microbial community level physiological profiles (sole C source tests). These data suggest soil microbial indicators can be useful indicators of pollutant heavy metal stress on the health of urban soils.     

Assessment of the environmental contamination with long-lived radionuclides around an operating RBMK reactor station

The presence of man-made gamma emitting radionuclides in the region within 32km radius of the Ignalina NPP/Lithuania has been investigated during the period 2001-2004, prior to the closure of the first of the two operating RBMK 1500-type reactors. Gamma spectrometric measurements of various terrestrial and aquatic plants as well as of soil samples showed moderate environmental contamination with the fission product (137)Cs and with the neutron activation products (60)Co and (54)Mn. Traces of the activation products (65)Zn and (110m)Ag were found in the nearest vicinity of the NPP. Activity concentrations were inhomogeneously distributed in the area of interest. Moss and algae samples showed the highest uptake of radionuclides. In addition to the gamma spectrometric measurements, the levels of (14)C were determined in the same bio-indicator samples using accelerator mass spectrometry.     

Work-related deaths in Washington State, 1998-2002

INTRODUCTION: In Washington State, 87 workers are killed each year, on average, while in work status. To understand these incidents and to assist in focusing on and development of potential prevention measures, they must be well characterized. METHODS: Work-related fatalities between the years 1998 and 2002 are described by the demographics of the victims, types of incidents, the victims' occupations, and industries and location in which they worked. RESULTS: Motor vehicle- and machinery-related incidents accounted for nearly 33% and 14% of the incidents, respectively. Agriculture, forestry, fishing, hunting, and mining (n=87), and construction (n=83) had the most fatalities. Fatality rates per 100,000 workers for these industries were 25.7 and 8.7, respectively, compared to the state-wide average of 3.1 fatalities/100,000 workers. DISCUSSION: These data indicate numerous areas for prevention of work-related traumatic injuries and fatalities.     

Community‐based preparedness programmes and the 2009 Australian bushfires: policy implications derived from applying theory

The Victorian Country Fire Authority in Australia runs the Community Fireguard (CFG) programme to assist individuals and communities in preparing for fire. The objective of this qualitative research was to understand the impact of CFG groups on their members' fire preparedness and response during the 2009 Australian bushfires. Social connectedness emerged as a strong theme, leading to an analysis of data using social capital theory. The main strength of the CFG programme was that it was driven by innovative community members; however, concerns arose regarding the extent to which the programme covered all vulnerable areas, which led the research team to explore the theory of diffusion of innovation. The article concludes by stepping back from the evaluation and using both applied theories to reflect on broad options for community fire preparedness programmes in general. The exercise produced two contrasting options for principles underlying community fire preparedness programmes.     

Temporal, spatial, and body size effects on growth rates of loggerhead sea turtles (Caretta caretta) in the Northwest Atlantic

In response to a call from the US National Research Council for research programs to combine their data to improve sea turtle population assessments, we analyzed somatic growth data for Northwest Atlantic (NWA) loggerhead sea turtles (Caretta caretta) from 10 research programs. We assessed growth dynamics over wide ranges of geography (9–33°N latitude), time (1978–2012), and body size (35.4–103.3 cm carapace length). Generalized additive models revealed significant spatial and temporal variation in growth rates and a significant decline in growth rates with increasing body size. Growth was more rapid in waters south of the USA (<24°N) than in USA waters. Growth dynamics in southern waters in the NWA need more study because sample size was small. Within USA waters, the significant spatial effect in growth rates of immature loggerheads did not exhibit a consistent latitudinal trend. Growth rates declined significantly from 1997 through 2007 and then leveled off or increased. During this same interval, annual nest counts in Florida declined by 43 % (Witherington et al. in Ecol Appl 19:30–54, 2009) before rebounding. Whether these simultaneous declines reflect responses in productivity to a common environmental change should be explored to determine whether somatic growth rates can help interpret population trends based on annual counts of nests or nesting females. Because of the significant spatial and temporal variation in growth rates, population models of NWA loggerheads should avoid employing growth data from restricted spatial or temporal coverage to calculate demographic metrics such as age at sexual maturity.     

Evacuation, escape, and rescue experiences from offshore accidents including the Deepwater Horizon

When a major hazard occurs on an installation, evacuation, escape, and rescue (EER) operations play a vital role in safeguarding the lives of personnel. There have been several major offshore accidents where most of the crew has been killed during EER operations. The major hazards and EER operations can be divided into three categories; depending on the hazard, time pressure and the risk influencing factors (RIFs). The RIFs are categorized into human elements, the installation and hazards. A step by step evacuation sequence is illustrated. The escape and evacuation sequence from the Deepwater Horizon offshore drilling platform is reviewed based on testimonies from the survivors. Although no casualties were reported as a result of the EER operations from the Deepwater Horizon, the number of survivors offers a limited insight into the level of success of the EER operations. Several technical and non-technical improvements are suggested to improve EER operations. There is need for a comprehensive analysis of the systems used for the rescue of personnel at sea, life rafts and lifeboats in the Gulf of Mexico.