Telomere dynamics in the Sydney rock oyster (<Emphasis Type="Italic">Saccostrea glomerata</Emphasis>): an investigation into the effects of age,tissue type,location and time of sampling

Telomere length has been purported as a biomarker for age and could offer a non-lethal method for determining the age of wild-caught individuals. Molluscs, including oysters and abalone, are the basis of important fisheries globally and have been problematic to accurately age. To determine whether telomere length could provide an alternative means of ageing molluscs, we evaluated the relationship between telomere length and age using the commercially important Sydney rock oyster (Saccostrea glomerata). Telomere lengths were estimated from tissues of known age individuals from different age classes, locations and at different sampling times. Telomere length tended to decrease with age only in young oysters less than 18 months old, but no decrease was observed in older oysters aged 2–4 years. Regional and temporal differences in telomere attrition rates were also observed. The relationship between telomere length and age was weak, however, with individuals of identical age varying significantly in their telomere length making it an imprecise age biomarker in oysters.     

The Green Village project: a rural community's journey towards sustainability

In the South West of the UK, a growing number of rural and urban communities are exploring various pathways to a more sustainable living. The village of Belstone is among these pioneers of change through its Green Village project. It is a relatively affluent community and it has been a major challenge to engage people that are reticent to change their lifestyle and suspicious of the motives of the initiators. Based on a process of action research, this paper explores the attitudes and perceptions towards sustainability and how they influenced the people's engagement. We demonstrate that the partnership was effective in enabling the villagers engaged in the project to take control over the process. Behaviour changes were reported by the villagers actively engaged with the initiative. The Green Village did not “snowball” to the entire community; however, many of those who chose not to engage associated the word “Green” with traits that they did not identify with.     

Radiation-induced adaptive response in fish cell lines

There is considerable interest at present in low-dose radiation effects in non-human species. In this study gamma radiation-induced adaptive response, a low-dose radiation effect, was examined in three fish cell lines, (CHSE-214 (Chinook salmon), RTG-2 (rainbow trout) and ZEB-2J (zebrafish)). Cell survival after exposure to direct radiation with or without a 0.1 Gy priming dose, was determined using the colony forming assay for each cell line. Additionally, the occurrence of a bystander effect was examined by measuring the effect of irradiated cell culture medium from the fish cell lines on unexposed reporter cells. A non-linear dose response was observed for all cell lines. ZEB-2J cells were very sensitive to low doses and a hyper-radiosensitive (HRS) response was observed for doses <0.5 Gy. A typical protective adaptive response was not detected in any of the three fish cell lines tested. Rather, it was found that pre-exposure of these cells to 0.1 Gy radiation sensitized the cells to subsequent high doses. In CHSE-214 cells, increased sensitivity to subsequent high doses of radiation was observed when the priming and challenge doses were separated by 4 h; however, this sensitizing effect was no longer present when the interval between doses was greater than 8 h. Additionally, a "protective" bystander response was observed in these cell lines; exposure to irradiated medium from fish cells caused increased cloning efficiency in unirradiated reporter cells. The data confirm previous conclusions for mammalian cells that the adaptive response and bystander effect are inversely correlated and contrary to expectations probably have different underlying mechanisms.     

Evaluating the sustainability potential of a white goods refurbishment program

A sustainable national policy on waste electronic and electrical equipment reuse has to ensure an integrated environmental economic and social approach. In this paper, a quantitative model is developed that permits a comparative analysis of re-use and non-re-use scenarios from an environmental and economic perspective. The model demonstrates the importance of considering user consumption profiles and the changing national electricity generation portfolio in determining the best end-of-life strategy, whether it should be reuse or recycling. A case study of Ireland is used to demonstrate the model. From a social perspective, qualitative aspects of reuse, such as the job creation potential and the impact on prosperity for low income families, are also considered. Reuse of white goods, if conducted through social enterprises, will create more employment than an equivalent amount of recycling for those most vulnerable to unemployment. Any environmental and social dividends from re-use can be realized only in the context of an economically sustainable system. This would include such factors as a secure supply of suitable equipment, a competitive cost base and sufficient revenues from sales and other sources in order for the business to survive. In an attempt to examine whether a white goods re-use program could possibly operate in a competitive manner with new appliances, this study has examined examples of comparable businesses operating in the EU as well as interpreting data on consumer demand.     

Herbivores enable plant survival under nutrient limited conditions in a model grazing system

We make a theoretical study of nitrogen cycling in a model of a grazing system with five compartments. The rates of uptake of nutrient by plants and herbivores are allowed nonlinear forms which involve no a priori assumptions about whether the system is subject to top-down or bottom-up control. We derive a method of piecewise linear approximation which allows analytical study of the system. We then use this method to investigate the properties of the equilibrium states of the system, and in particular whether the system favours donor- or recipient-control, the grazing optimization problem, and the potential benefits of herbivory to plant growth. We are able to generalise our results to all uptake functions of the same qualitative class as those considered, and to show that in general the system will tend to a stable equilibrium state of donor-controlled herbivory. In this model, the presence of the ‘right’ class of herbivore is not only beneficial to plant growth in certain circumstances, but can be essential to their survival, allowing plants to co-exist with herbivores under conditions in which they would be unable to survive alone.     

Invasional meltdown: invader-invader mutualism facilitates a secondary invasion

In multiply invaded ecosystems, introduced species should interact with each other as well as with native species. Invader-invader interactions may affect the success of further invaders by altering attributes of recipient communities and propagule pressure. The invasional meltdown hypothesis (IMH) posits that positive interactions among invaders initiate positive population-level feedback that intensifies impacts and promotes secondary invasions. IMH remains controversial: few studies show feedback between invaders that amplifies their effects, and none yet demonstrate facilitation of entry and spread of secondary invaders. Our results show that supercolonies of an alien ant, promoted by mutualism with introduced honeydew-secreting scale insects, permitted invasion by an exotic land snail on Christmas Island, Indian Ocean. Modeling of land snail spread over 750 sites across 135 km2 over seven years showed that the probability of land snail invasion was facilitated 253-fold in ant supercolonies but impeded in intact forest where predaceous native land crabs remained abundant. Land snail occurrence at neighboring sites, a measure of propagule pressure, also promoted land snail spread. Site comparisons and experiments revealed that ant supercolonies, by killing land crabs but not land snails, disrupted biotic resistance and provided enemy-free space. Predation pressure on land snails was lower (28.6%), survival 115 times longer, and abundance 20-fold greater in supercolonies than in intact forest. Whole-ecosystem suppression of supercolonies reversed the probability of land snail invasion by allowing recolonization of land crabs; land snails were much less likely (0.79%) to invade sites where supercolonies were suppressed than where they remained intact. Our results provide strong empirical evidence for IMH by demonstrating that mutualism between invaders reconfigures key interactions in the recipient community. This facilitates entry of secondary invaders and elevates propagule pressure, propagating their spread at the whole-ecosystem level. We show that identification and management of key facilitative interactions in invaded ecosystems can be used to reverse impacts and restore resistance to further invasions.     

Acute and reproductive toxicity of nano-sized metal oxides (ZnO and TiO₂) to earthworms (Eisenia fetida)

An increase in nanomaterial applications will likely lead to an increased probability of environmental exposures, raising concerns regarding the safety of these materials. Recent studies have indicated that manufactured nanomaterials, such as metal oxides, have the potential to be harmful to aquatic and terrestrial organisms. The majority of nano-metal oxide research addressing potential toxicological issues has been focused in aquatic environments with very little terrestrial data. This study characterized the acute and reproductive toxicity of zinc oxide (ZnO) and titanium dioxide (TiO(2)) to earthworms (Eisenia fetida) in a terrestrial system. Following a 14 d exposure, nano-sized ZnO on filter paper was acutely toxic to E. fetida, while nano-sized TiO(2) did not exhibit acute toxicity. In contrast, neither nano-sized ZnO nor TiO(2) exhibited acute toxicity to earthworms in sand. Both nano-sized ZnO and TiO(2), following a 4 week exposure, caused reproductive effects in earthworms in artificial soil. Overall, nano-sized ZnO exhibited greater toxicity than nano-sized TiO(2) in Eisenia fetida.     

Behavior of potentially toxic elements from stoker-boiler fly ash in Interior Alaska: paired batch leaching and solid-phase characterization

Environmental Science and Pollution Research - Despite significant investigation of fly ash spills and mineralogical controls on the release of potentially toxic elements (PTEs) from fly ash,...     

On estimating the exponent of power-law frequency distributions

Power-law frequency distributions characterize a wide array of natural phenomena. In ecology, biology, and many physical and social sciences, the exponents of these power laws are estimated to draw inference about the processes underlying the phenomenon, to test theoretical models, and to scale up from local observations to global patterns. Therefore, it is essential that these exponents be estimated accurately. Unfortunately, the binning-based methods traditionally used in ecology and other disciplines perform quite poorly. Here we discuss more sophisticated methods for fitting these exponents based on cumulative distribution functions and maximum likelihood estimation. We illustrate their superior performance at estimating known exponents and provide details on how and when ecologists should use them. Our results confirm that maximum likelihood estimation outperforms other methods in both accuracy and precision. Because of the use of biased statistical methods for estimating the exponent, the conclusions of several recently published papers should be revisited.     

Fine-scale chemical fingerprinting of an open coast crustacean for the assessment of population connectivity

Chemical fingerprinting techniques recently have been used to track larval dispersal of estuarine species that bear calcified structures, but the applicability of this important approach may be limited on the open coast where chemical signatures may be less distinctive and for the many species that do not retain calcified structures throughout development. Externally brooded embryos of the porcelain crab, Petrolisthes cinctipes, and inductively coupled plasma mass spectrometry were used to determine whether fine-scale variation in trace-elemental composition occurred along an open coast. Embryos were collected from 16 sites from 37.8° to 39.5° north latitude along the Pacific Coast of California, USA during late January and early February 2003. Discriminant function analysis revealed that collection sites, many separated by only a few kilometers along an open coast, could be differentiated with an overall accuracy of 73%, and combining the sites into three regions increased the accuracy to 88%. Thus, distinctive elemental signatures can be detected in open coast species even at a fine scale raising the possibility that larval tags can be developed for many more species than previously thought possible.