Rising water temperature in rivers: Ecological impacts and future resilience

Rising water temperatures in rivers due to climate change are already having observable impacts on river ecosystems. Warming water has both direct and indirect impacts on aquatic life, and further aggravates pervasive issues such as eutrophication, pollution, and the spread of disease. Animals can survive higher temperatures through physiological and/or genetic acclimation, behavioral and phenological change, and range shifts to more suitable locations. As such, those animals that are adapted to cool-water regions typically found in high altitudes and latitudes where there are fewer dispersal opportunities are most at risk of future extinction. However, sub-lethal impacts on animal physiology and phenology, body-size, and trophic interactions could have significant population-level effects elsewhere. Rivers are vulnerable to warming because historic management has typically left them exposed to solar radiation through the removal of riparian shade, and hydrologically disconnected longitudinally, laterally, and vertically. The resilience of riverine ecosystems is also limited by anthropogenic simplification of habitats, with implications for the dispersal and resource use of resident organisms. Due to the complex indirect impacts of warming on ecosystems, and the species-specific physiological and behavioral response of organisms to warming, predicting how river ecosystems will change in the future is challenging. Restoring rivers to provide connectivity and heterogeneity of conditions would provide resilience to a range of expected co-occurring pressures, including warming, and should be considered a priority as part of global strategies for climate adaptation and mitigation. This article is categorized under: Science of Water > Water and Environmental Change Water and Life > Nature of Freshwater Ecosystems Water and Life > Stresses and Pressures on Ecosystems

Modelling strain localization by cohesive (overlapping) zones in tension (compression): brittleness size effects and scaling in material properties

The present paper is a state-of-the-art review of the research carried out at the Politecnico di Torino during the last two decades on the modelling of strain localization. Introducing the elementary cohesive/overlapping models in tension/compression, it will be shown that it is possible to get a deep insight into the ductile-to-brittle transition and into the scaling of the material properties usually detected when testing quasi-brittle material specimens or structures at different size-scales