Climate change adaptation strategies in the Mekong and Orange-Senqu basins: What determines the state-of-play?

The challenge of governing transboundary water resources is expected to increase with climate change and the resulting need to adapt to its impacts such as temperature increase, more precipitation in the wet season and less in the dry season. In a number of transboundary basins, international regimes, and in particular river basin commissions, are emerging to account for this and other challenges. Some basins are, however, rather advanced in terms of developing climate change adaptation strategies, while others are in a more nascent stage. For the two case studies of the Orange-Senqu and Mekong river basins, this paper attempts to explain the different degrees of progress towards climate change adaptation by applying regime effectiveness analysis. First, we analyze, using the Activity Diagram (AD) of the Management and Transition Framework (MTF), at which stage in the climate change adaptation policy formation process each of the two basins is. Then we attempt to explain the different degrees of progress towards adaptation by means of regime effectiveness theory. Variables indicating regime effectiveness are taken from the literature and further developed to suit the context of climate change adaptation. We find that the different degrees of progress can partially be explained by some variables of regime effectiveness such as the characteristics of rules and procedures, organizational structure, the role of riparian countries as well as international context. At the same time, the analysis points to the need for an analysis of additional factors that potentially shape decision-making and policy processes for climate change adaptation in international river basins such as (a) the hydrological, political and socio-economic setting, (b) underlying principles of regional cooperation (or conflict), (c) interests and values of the various actors in the negotiation process and (d) the possible linkages and trade-offs with other policy fields.     

Reproductive division of labour coevolves with gall size in Australian thrips with soldiers

An analysis of multiple species of Australian gall-inducing thrips with soldiers reveals a significant negative correlation between the size of gall produced and the reproductive division of labour. This correlation suggests that the evolution of smaller galls limited the available space and feeding sites for the offspring of female soldiers, and was a major factor that led to the evolution of an altruistic caste in the gall-inducers. We argue that high levels of inbreeding by singly mated foundresses and incestuous mating by her soldier offspring are key to this evolutionary relationship because they make the relatedness of a female soldier to her daughters and sisters approximately equal. Evidence that relatedness plays an important role is strengthened by the observation of outbred multiply mated foundresses and unbiased sex ratio of dispersers in Oncothrips waterhousei, and the inference that both gall volume and skew decreased along this lineage.     

Reproduction of the estuarine and marine amphipod Corophium volutator (Pallas) in laboratory for toxicity testing

The acute whole sediment bioassay with the estuarine and marine amphipod Corophium volutator (Pallas) is broadly used within Europe. Hitherto, the test is carried out with field-collected animals. In order to provide a more standardized and continuously available test organism reproduction and growth experiments were performed for a period of one year in laboratory under simulated summer conditions (light/dark 16:8 at 15, 19, and 23 degrees C). C. volutator was the first time reproduced successfully in laboratory for several generations and independent from its natural life cycle also in winter. The females produced two to three broods with a mean number of 96 offspring. A mean growth rate of 0.07 mm per day was determined at 15 degrees C. The reproduction and growth experiments provide consequently the essential base for the development of a chronic toxicity test with C. volutator.     

Influence of compost amendment rate and level of compaction on the hydraulic functioning of soils

There has been widespread interest in using compost to improve the hydrologic functions of degraded soils at construction sites for reducing runoff and increasing infiltration. The objective of this study was to determine the effects of compost amendment rate on saturated hydraulic conductivity (K_s) and water retention in order to identify target compost rates for enhancing soil hydrologic functions. Samples were prepared with three soil textures (sandy loam, silt loam, and sandy clay loam), amended with compost at 0%, 10%, 20%, 30%, 40%, and 50%. All soils were tested at a porosity of 0.5 m³/m³, and the sandy loam was further tested at high (0.55 m³/m³) and low (0.4 m³/m³) porosities. The K_s and water retention data were then used to model infiltration with HYDRUS-1D. With increasing compost amendment rate, K_s and water retention of the mixtures generally increased at the medium porosity level, with more compost needed in heavier soils. As porosity decreased in the sandy loam soil, the amount of compost needed to improve K_s rose from 20% to 50%. Water distribution in pore fractions (gravitational, plant-available, and unavailable water) depended on texture, with only the highest compost rates increasing plant-available water in one soil. Results suggest soil texture should be taken into consideration when choosing a compost rate in order to achieve soil improvement goals. Hydrologic benefits may be limited even at a high rate of compost amendment if soil is compacted.