Vegetation associated with different walking track types in the Kosciuszko alpine area, Australia

Tourism infrastructure such as walking tracks can have negative effects on vegetation including in mountain regions. In the alpine area around continental Australia's highest mountain, Mt Kosciuszko (2228 m), there is a range of walking tracks (paved, gravel and raised steel mesh surfaces) in addition to an extensive network of informal/non-hardened tracks. Vegetation characteristics were compared between track types on/under tracks, on the track verge, and in the adjacent native vegetation. For a raised steel mesh walkway there was no difference in vegetation under the walkway, on the verge, and 3m away. In contrast, for a non-hardened track there was 35% bare ground on the track surface but no other detectable impacts. Gravel and paved tracks had distinct verges largely comprising bare ground and exotic species. For non-hardened tracks there was an estimated 270 m2 of disturbance per km of track. For wide gravel tracks the combined area of bare ground, exotic plants and gravel was estimated as 4290 m2 per km, while for narrow gravel tracks it was estimated as 2940 m2 per km. For paved tracks there was around 2680 m2 per km of damage. In contrast, there was no detectable effect of raised steel mesh walkway on vegetation highlighting some of the benefits of this surface over other track types.     

A method to estimate pre-exploitation population size

Antarctic fur seals (Arctocephalus gazella) were commercially exploited on the subantarctic island of South Georgia for over 100 years and nearly driven to extinction. Since the cessation of harvesting, however, their populations have rebounded, and they are now often considered a nuisance species whose impact on the terrestrial landscape should be mitigated. Any evaluation of their current population requires the context provided by their historic, pre-exploitation abundance, lest ecologists fall prey to shifting baseline syndrome in which their perspective on current abundance is compared only with an altered state resulting from past anthropogenic disturbance. Estimating pre-exploitation abundance is critical to defining species recovery and setting recovery targets, both of which are needed for the International Union for the Conservation of Nature's recent efforts to develop a green list of recovering species. To address this issue, we reconstructed the South Georgia fur seal harvest from 1786 to 1908 from ship logbooks and other historical records and interpolated missing harvest data as necessary with a generalized linear model fit to the historical record. Using an approximate Bayesian computation framework, harvest data, and a stochastic age-structured population model, we estimated the pre-exploitation abundance of Antarctic fur seals on South Georgia was 2.5 million females (95% CI 1.5–3.5 million). This estimate is similar to recent abundance estimates, and suggests current populations, and the ecological consequences of so many fur seals on the island, may be similar to conditions prior to human harvest. Although the historic archive on the fur sealing era is unavoidably patchy, the use of archival records is essential for reconstructing the past and, correspondingly, to understanding the present. Article impact statement: Defining species recovery requires an understanding of baseline population state, which can be estimated through statistical methods.     

Laboratory and field estimates of the rate of faecal pellet production by Antarctic krill,Euphausia superba

The time course of faecal pellet production (egestion) was monitored in January 1985 for a population of Antarctic krill, Euphausia superba Dana, maintained in flowing seawater aquaria at Palmer Station, Antarctica. Following transfer to filtered seawater, krill produced faecal strings for roughly 40 min, after which time faecal egestion virtually ceased. Similar results were obtained for freshly-trawled krill at sea in February and March 1985. There were wide daily variations in total faecal egestion rate; mean rates varied from 0.54 to 1.66 mg dry wt h^-1 and individual rates from 0.25 to 2.35 mg h^-1 (all data corrected to a standard krill of 600 mg fresh weight). Despite these wide fluctuations in total faecal egestion, the loss of organic matter showed no significant daily variation, with a mean value of 0.13 mgh^-1. The relationship between faecal egestion rate and faecal organic content suggested that feeding rate was governed by food quality; when inorganic load was high, feeding rate increased to ensure sufficient energy intake. The data suggest that superfluous feeding does not occur in krill and that values of gut-clearance time calculated from time intervals greater than about 40 min will not be representative of previous feeding history. the rates of faecal egestion observed in this study indicate that the flux of faecal pellets from krill is substantial. They imply an energy intake in E. superba of 17 to 28% body weight per day, much higher than estimated previously for this species by summing known energy losses, but similar to estimates for other euphausiids.     

Comparative assessment of wet and dry garment cleaning Part 1. Environmental and human health assessment

Water-based cleaning of specialty garments is emerging as a potential alternative to dry cleaning. Perchloroethylene, the solvent used in dry cleaning, poses significant human and ecosystem health concerns. This paper is part 1 of a two part series that analyzes the key environmental, human health, performance, economic, and regulatory factors which influence the future of the garment cleaning industry. This paper inventories the environmental releases and wastes associated with the consumption of perchloroethylene in modern dry cleaning machines which ranges from 2.0 to 5.2 kg per 100 kg of clothing cleaned. In addition, water, electricity, and other inputs for both perchloroethylene-based and water-based garment cleaning are compared using data from previous demonstration projects. Toxicological and epidemiological studies provide evidence for the carcinogenicity of perchloroethylene although this classification is controversial. Cancer risks at low levels of exposure associated with modern dry cleaning equipment and good housekeeping practices are unknown and require further investigation. Regardless of these uncertainties, water-based cleaning is preferable to dry cleaning from a human and environmental health perspective.