Coastal dune conservation on an Irish commonage: community-based management or tragedy of the commons?

In Ireland 'commonage' refers to lands jointly owned by several individuals who have grazing rights. Commonage can provide the low-intensity grazing regime regarded as optimal for habitat conservation, and it is also unlikely to suffer the negative impacts of building development or coastal engineering. Today, however, the traditional control systems of coastal commonage are generally moribund, leading to habitat degradation. The only viable future management model is likely to be one based on local community control. Community management would have the legitimacy to counter the negative perceptions of external authority that generate environmental degradation.     

A preliminary investigation of boundary layer effects on daytime atmospheric CO<Subscript>2</Subscript> concentrations at a mountaintop location in the Rocky Mountains

Observations of CO₂ concentration at a mountaintop in the Colorado Rockies in summer show a large diurnal variability with minimum CO₂ concentrations found between 10:00 and 18:00 MST. Simulations are performed with a mesoscale model to examine the effects of atmospheric structure and large-scale flows on the diurnal variability. In the simulations initialized without large-scale winds, the CO₂ minimum occurs earlier compared to the observations. Upslope flows play an important role in the presence of this early (pre-noon) minimum while the timing and magnitude of the minimum depend only weakly on the temperature structure. An increase in large-scale flow has a noticeable impact on the diurnal variability with a more gradual decrease in daytime CO₂ concentration, similar to summer-averaged observations. From the idealized simulations and a case study, it is concluded that multi-scale flows and their interactions have a large influence on the observed diurnal variability.     

Geo-politics and freshwater fish introductions: How the Cold War shaped Europe's fish allodiversity

Activities that manipulate ecosystems to support economic activities provide major introduction pathways for non-native species. As such, substantial differences in the socioeconomic conditions between countries could influence how ecosystems are manipulated and thus impact the composition of their communities of non-native species. Here, we compared the influence of freshwater fish aquaculture production and macro-socioeconomic drivers on the freshwater fish allodiversity of Europe between 1970 and 2009. A divergence in the socio-economic conditions of Europe prevailed during much of the latter half of the 20th Century as a result of the Cold War. For example, GDP and GDP per capita were significantly higher in Western bloc countries compared to the Eastern bloc. In this 39 year period, aquaculture production in Eastern bloc countries was dominated by Asian cyprinid fish whereas in Western bloc countries it was dominated by the North American rainbow trout Oncorhynchus mykiss. Analysis of a European database on introduced fish into the wild from aquaculture revealed that in entirety, there were 279 separate freshwater fish introductions in Europe associated with aquaculture (Eastern bloc 118, Western bloc 161), involving 117 species from 32 families. There was relatively low homogeneity in these introduced fishes between the two blocs; only 28 species were introduced into both. Western bloc countries also had significantly more introduced fishes and more introduction events, and less similarity in the introduced fishes between their countries. Aquaculture production was a significant predictor of the number of non-native freshwater fish across all the countries, although additional factors, especially human population size and GDP per capita, were also significant predictors. Thus, aquaculture has been a strong introduction pressure in Europe and provides a reliable predictor of fish allodiversity.     

The effect of photoionization on the cooling rates of enriched, astrophysical plasmas

Radiative cooling is central to a wide range of astrophysical problems. Despite its importance, cooling rates are generally computed using very restrictive assumptions, such as collisional ionization equilibrium and solar relative abundances. We simultaneously relax both assumptions and investigate the effects of photoionization of heavy elements by the metagalactic ultraviolet (UV)/X-ray background and of variations in relative abundances on the cooling rates of optically thin gas in ionization equilibrium. We find that photoionization by the metagalactic background radiation reduces the net cooling rates by up to an order of magnitude for gas densities and temperatures typical of the shock-heated intergalactic medium and proto-galaxies  (10⁴ K ≲ T ≲ 10⁶ K, ρ/〈ρ〉≲ 100)  . In addition, photoionization changes the relative contributions of different elements to the cooling rates. We conclude that photoionization by both the ionizing background and heavy elements needs to be taken into account in order for the cooling rates to be correct to an order of magnitude. Moreover, if the rates need to be known to better than a factor of a few, then departures of the relative abundances from solar need to be taken into account. We propose a method to compute cooling rates on an element-by-element basis by interpolating pre-computed tables that take photoionization into account. We provide such tables for a popular model of the evolving UV/X-ray background radiation, computed using the photoionization package cloudy .