Socio-economic and management implications of range-shifting species in marine systems

Climate change is leading to a redistribution of marine species, altering ecosystem dynamics as species extend or shift their geographic ranges polewards with warming waters. In marine systems, range shifts have been observed in a wide diversity of species and ecosystems and are predicted to become more prevalent as environmental conditions continue to change. Large-scale shifts in the ranges of marine species will likely have dramatic socio-economic and management implications. Australia provides a unique setting in which to examine the range of consequences of climate-induced range shifts because it encompasses a diverse range of ecosystems, spanning tropical to temperate systems, within a single nation and is home to global sea surface temperature change ‘hotspots’ (where range shifts are particularly likely to occur). We draw on global examples with a particular emphasis on Australian cases to evaluate these consequences. We show that in Australia, range shifts span a variety of ecosystem types, trophic levels, and perceived outcomes (i.e., negative versus positive). The effect(s) of range shifts on socio-economic change variables are rarely reviewed, yet have the potential to have positive and/or negative effects on economic activities, human health and ecosystem services. Even less information exists about potential management responses to range-shifting species. However, synthesis of these diverse examples provides some initial guidance for selecting effective adaptive response strategies and management tools in the face of continuing climate-mediated range shifts.     

Influence of frozen conditions on the oxygen diffusion coefficient in unsaturated porous materials

The efficiency of soil covers used as oxygen barriers to control the generation of acid drainage from sulfidic mine wastes can be evaluated in terms of the diffusive oxygen flux reaching the underlying wastes. Oxygen diffusion has been extensively investigated over the last few decades for unsaturated porous materials that are not frozen. However, little attention has been paid to materials that are fully or partially frozen, and thus, the diffusion of oxygen through soil covers during the winter freezing period has been generally neglected. This paper presents a laboratory method developed to evaluate the effective diffusion coefficient of oxygen (D_e) in frozen, inert materials. The method is a modified version of the conventional double-chamber cell in which the temperature and unfrozen volumetric water content of the sample are measured in addition to the more commonly monitored change in oxygen concentration. Several tests were conducted on non-reactive materials: that is, a sand at multiple degrees of saturation (S_r?=?20, 30, 39, and 42%), a silt (S_r?=?47%), and a mixture of the two (S_r?=?90%). Experimental data were interpreted using the POLLUTE code. Values of D_e for frozen materials were slightly lower than those obtained at ambient laboratory temperatures. In addition to the development of an empirical method for determining D_e, a preliminary model based on the model proposed by Aachib et al. (Water Air Soil Pollut 156:163–193, 2004) was created for the prediction of D_e in frozen materials by defining the involved parameters as temperature-dependent. The results indicate that predicated values of D_e are slightly higher than experimental values, suggesting that there remains room for improvement in the model.