A practical look at the variable area transect

The variable area transect (VAT) is a plotless density estimator that has received little attention in the ecological literature despite having potentially robust estimation properties. VAT allows for density estimations without the lengthy search times associated with other plotless density estimators. In spite of this, little has been written about the effect of varying transect widths on its density estimation properties or on the practical implementation of the VAT in field settings. An artificial population sampler was used to examine the effect of transect width on density estimates obtained using the VAT. Three transect widths were chosen corresponding to the mean object size, the largest object size, and twice the size of the largest object. Transect width had a marked effect on the quality of the density estimation, with the largest transect width resulting in significant negative biases in estimation. For the narrowest width, most estimates were within 10% of the true value for a nonrandomly distributed population. The practical considerations of choosing a VAT transect width are enumerated.     

Economic and employment impacts of offshore wind for Ireland: A value chain analysis

ABSTRACT

The imminent development of a number of offshore wind farms in the Republic of Ireland presents a sizable opportunity to stimulate the Irish economy through the growth of an indigenous and globally competitive offshore wind supply chain. This study uses a value chain analysis to evaluate the economic and employment potential of the offshore wind sector for Ireland. The analysis is based on the expenditure on products and services required to develop an offshore wind farm, the planned capacity of projects in the pipeline, and the ability of Irish companies to supply the sector. Results suggest that by 2030, 2.5–4.5GW of domestic offshore wind development could create between 11,424 and 20,563 supply chain jobs and generate between €763 m and €1.4bn in gross value added. This is the first study to estimate domestic GVA potential for the sector.     

English county councils and their agenda for waste minimisation

Minimisation is the top priority of the waste management hierarchy, which is one of the guiding principals for national solid waste management planning throughout the developed world. As such it should be encouraged as a means for reducing wastes which require treatment and disposal, whether they be household, commercial or industrial in source. This paper suggests that minimisation is not being given the necessary policy frameworks or legislation within which to develop in the UK, and questions whether minimisation is being afforded the respect and attention, from all levels, that is due the most preferable waste option according to the hierarchy. This theme is investigated by surveying the county councils of England as a representative sample of waste disposal authorities in England, and former waste regulation authorities. They are responsible for guiding local and district waste policy and are the regional waste planners in the UK. If they are not seriously taking on board the message of minimisation, then there is little chance that it will succeed without further legislative developments. Some 59% of English counties have a minimisation policy, whilst only 47% have participated in and supported a minimisation programme or trial within their region. The majority of these developments have occurred within the last three years, and 78% of counties who have participated in a programme have found it a successful venture. By 1999 79% of English counties will have been actively involved in a minimisation programme in their region, which is a positive scenario. This trend must continue if waste minimisation is to become the key theme of future sustainable waste management in the UK as was intended by declarations at the Rio '92 conference and in subsequent UK Government policy and strategy.     

Evaluation of alternatives for extending the life of landfills

Given the difficulty, as well as the high cost, of siting and constructing municipal solid waste (MSW) landfills it is incumbent on landfill managers to evaluate all practical measures to extend the useful life of existing landfills. This necessitates not only identifying potential methods to extend their life, but also the means to assess at what time horizons in the landfill's life such measures are cost effective. Some typical examples of methods to extend their life include: size reduction of incoming waste, improved in-place compaction density, use of alternative daily cover, waste diversion, and accelerating the degradation to enhance attendant settlement on the MSW. Most, if not all, of these methods incur capital/operating costs that must be evaluated. The methodology for this analysis is presented using the existing landfill at Andersen Air Force Base (AAFB), Guam, as a model for the procedure. The Landfill Extension Model (LEM) computer program was written to model the AAFB landfill and to analyze various extension alternatives to include compaction, shredding, alternative daily cover and operation outsourcing (contracting). The LEM computer program may be used to evaluate any landfill operation and is consequently useful for evaluating any existing landfill. It was found that by utilizing all of the proposed alternatives the life of AAFB landfill could be extended from 10 years to 48 years.     

The Route to Best Science in Implementation of the Endangered Species Act’s Consultation Mandate: The Benefits of Structured Effects Analysis

The Endangered Species Act is intended to conserve at-risk species and the ecosystems upon which they depend, and it is premised on the notion that if the wildlife agencies that are charged with implementing the statute use the best available scientific information, they can successfully carry out this intention. We assess effects analysis as a tool for using best science to guide agency decisions under the Act. After introducing effects analysis, we propose a framework that facilitates identification and use of the best available information in the development of agency determinations. The framework includes three essential steps—the collection of reliable scientific information, the critical assessment and synthesis of available data and analyses derived from those data, and the analysis of the effects of actions on listed species and their habitats. We warn of likely obstacles to rigorous, structured effect analyses and describe the extent to which independent scientific review may assist in overcoming these obstacles. We conclude by describing eight essential elements that are required for a successful effects analysis.     

Genetic structure of the southeastern United States loggerhead turtle nesting aggregation: evidence of additional structure within the peninsular Florida recovery unit

The southeastern United States supports one of two large loggerhead turtle (Caretta caretta) nesting aggregations worldwide and is therefore critical to global conservation and recovery efforts for the species. Previous studies have established the presence of four demographically distinct nesting populations (management units) corresponding to beaches from (1) North Carolina through northeastern Florida, (2) peninsular Florida, (3) the Dry Tortugas, and (4) northwest Florida. Temporal and geographic genetic structure of the nesting aggregation was examined utilizing partial mitochondrial control region haplotype frequencies from 834 samples collected over the 2002 through 2008 nesting seasons from 19 beaches as well as previously published haplotype data. Most rookeries did not exhibit interannual genetic variation. However, the interannual variation detected did significantly impact the interpretation of spatial genetic structure in northeastern Florida. Based on pairwise F _ST comparisons, exact tests of population differentiation, and analysis of molecular variance, the present study upholds the distinctiveness of the four currently recognized management units and further supports recognition of discrete central eastern, southern (southeastern and southwestern), and central western Florida management units. Further subdivision may be warranted, but more intensive genetic sampling is required. In addition, tools such as telemetry and mark-recapture are needed to complement genetic data and overcome limitations of genetic markers in resolving loggerhead turtle rookery connectivity in the southeastern USA.