The goal of our proposed research is to understand how long-term warming of stream ecosystems influences their response (i.e., resistance and resilience) to increasing prevalence and intensity of hydrologic drought. Anthropogenic greenhouse gas emissions from human activities are generating both a rise in global temperatures and an increase in the frequency and intensity of extreme climatic events. While shifts in these drivers are known to affect the structure and function of running waters separately, few studies have investigated their combined or interactive effects. The prevailing view is that warming and drought will combine to produce more extreme ecological consequences than would result from either stressor alone. Yet, emerging evidence suggests that warming may trigger 'compensatory' responses - both adaptive and ecological - that may have the potential to lessen the impacts of extreme drought. Our collaborative NSFDEB-NERC project will combine laboratory measurements (University of Iceland), stream mesocosm manipulations of temperature and drought (University of Birmingham, U.K.), and whole-reach drought manipulations (Hengill geothermal catchment, Iceland) to test the overarching hypothesis that long-warming enhances stream ecosystem stability (both resistance and resilience) in response to drought events. Our first objective is focused at the individual level, investigating whether physiological adaptations to warming influence invertebrate carbon use efficiencies and their role in drought resilience and recovery. Our second objective seeks to quantify resistance and resilience of entire invertebrate communities and their biomass production in response to drought across natural and experimental thermal gradients. Our final objective will explore the potential for ecosystem-level compensatory responses by examining how warming-induced shifts in nutrient supply and primary producers influence stability of ecosystem metabolism and nitrogen uptake in response to drought.

IIn biology, stress is often a poorly defined concept, and one that is negatively associated with health in humans and animals. However, stress responses actually play an important positive role in maintaining viability and health. When challenged by a threat in the environment - perhaps a predator, disturbance, or adverse conditions - a set of neuroendocrine pathways trigger physiological and behavioural responses (e.g. fight or flight behaviours) that have evolved under natural selection to counter the threat. Nonetheless, while these acute stress responses are thought to be adaptive, it is also well documented that chronic stress exposure can reduce the health of individuals and sometimes - particularly when mothers are exposed - their offspring. Because chronic stress responses, also called "tertiary stress responses" (TSR) are typically bad for fitness (survival and/or reproduction), natural selection should act over evolutionary time to get rid of them. The fact that the TSR is widespread, being found in vertebrates ranging from fish to humans, therefore poses an important question- what constrains evolution of the stress response towards a state where these harmful, or maladaptive, effects do not occur? The goal of the proposed work is to answer this question by conducting a genetic study. We will use guppies as a model system, experimentally manipulating stressors in the environment, determining how different individuals and genotypes respond through behavioural and hormonal processes, and determining the long term consequences of this variation for fitness. In particular we will test two hypotheses about where the evolutionary constraint comes from that maintains the TSR. The first possibility is a trade-off between the effects of acute and chronic stress on fitness. In simple terms, genes that cause the TSR may persist in a population precisely because they are the ones that lead to the most appropriate acute stress responses. A second possibility is that, where mothers experience chronic stress, a trade-off occurs across the generations. Here, some maternal genotypes are better able than others to maintain the mother's own health, but do so at a cost to offspring (e.g. by reducing the amount of care she provides). Testing these hypotheses will shed light on the evolutionary processes that have shaped vertebrate stress responses in general. However, it is also expected that a better understanding of the genetics of chronic stress could yield tangible benefits for improving animal welfare in captive animal. For instance, if we understand how genes influencing aspects of the acute stress response contribute to the risk of developing disease under chronic stress, we might be able to select these traits so as to reduce health problems in livestock and aquaculture production in future.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

The breaking apart of a continent to form extended continental margins and ultimately ocean basins is a process that can last for 10s of millions of years. The start of this process of rifting is thought to contribute significantly to the structure and sedimentary layering of the continental margins that have formed by its end. Often the details of how rifting initiates and develops in the first few million years are lost in the complexities of deformation and thick sediment layers beneath the continent's edges. To understand the early phases, we have to study areas where rifting has only recently started, and the Gulf of Corinth, Greece, is a key example in its first few millions of years of history. Across the Gulf, the two sides of the rift are moving apart at up to 20 mm every year and this high rate of extension results in numerous earthquakes which historically have been very destructive. The rapid extension also results in a rapidly developing rift basin which is partially submerged beneath the sea and filling with sediments. Within the Gulf, a large volume of marine geophysical data has been collected, including detailed maps of the seabed, as well as seismic data that use sound sources to give cross-sections of material beneath the seabed. The seismic data allow us to directly image the accumulated sediment layers and to identify faults that offset the layers and create the basin. This project will integrate these data to make a very detailed interpretation of the sediment layers (and their likely age) and fault planes. Imaging and assigning ages to the layers, by comparing with models of climate and sea level change, allows us to determine how the basin has developed through time. The fault planes imaged by the data generate the extension and subsidence of the rift, and their history of activity controls how the basin develops. The results will be used to generate the first high resolution model of rift development over the initial few million years of a rift's history and will help to address some of the unanswered questions of how continents break apart. The model will be used by a range of scientists, including those trying to understand how tectonics, landscape morphology and climate all interact to cause sediments to move from one place to another: rift basins are one of the main sinks for sediments and we will calculate how the volume of sediment delivered to the Corinth basin has changed with time, as faults move and as climate changes. The majority of the world's petroleum resources are found in old rifts, but often details of how the rift developed and the detailed geometry of the rock units in which the oil is now found are masked by other geological processes and by shallower sediment layers. Understanding the early rift processes is important for determining where and what kind of sediments will be deposited in different parts of the basin with time. We will also analyse details of how individual faults grow and interact with other faults in the rift: this process affects where sediments enter a rift basin and is therefore also important for identifying petroleum reservoirs. The rift faults are responsible for the destructive earthquakes in central Greece, so this project's analysis of fault location and rate of slip will also help us to better understand the potential hazard, increasing the potential for reduction of associated risk. Ultimately, the project will be used to select sites for drilling and sampling the sediments of the rift zone, through the Integrated Ocean Drilling Program. These samples would provide: the actual age of sediment layers, and hence well resolved slip rates for each active fault and a test for the rift models generated here; and the types of sediments, that will tell us more about the regional climate of the last few millions of years and where sediments that typically form hydrocarbon reservoirs are located in this analogue for older rift systems like the North Sea.

Hundreds of millions of people live close to, and depend upon, the world's large rivers for water, food, transport and the maintenance of a thriving ecosystem. However, these rivers are increasingly vulnerable to the effects of a wide range of natural and human-induced disturbances, including climate change, construction of large dams, river engineering works, deforestation, agricultural intensification, and mining activity. Over the past 20 years, climate change and deforestation have impacted on the hydrology and sediment fluxes within the Amazon River Basin. However, the Amazon has remained one of the few large river systems that has been largely unaffected by dams. This situation is changing rapidly, because widespread hydropower dam construction in Brazil, Bolivia, Peru and Ecuador now threatens the basin, with >300 dams planned or under construction. These dams are expected to trigger severe hydro-physical and ecological disturbances throughout the basin, including massive reductions in sediment and nutrient delivery to the lowland Amazon and its floodplains, substantial degradation of river beds and banks, significant changes in river water levels and flooding, and adverse impacts on river and floodplain ecosystems, on which the human population depends. Recent high profile studies highlight the need for international action to assess and mitigate these impacts, both in the Amazon and elsewhere. However, our capacity to do this is severely restricted by an absence of quantitative models that can predict how environmental disturbances propagate through large rivers and floodplains, over continental distances, and decadal to centennial time periods. Critically, environmental disturbances driven by dams, climate and land cover change promote dynamic river responses (e.g., changes in river width, depth, slope, sediment size, degree of branching and rate of floodplain reworking), which in turn control changes in flood conveyance and downstream sediment delivery. Despite advances in modelling of river dynamics over short distances (<100 km), hydrological models that are applied to continental-scale drainage basins treat rivers and floodplains as static conduits. Consequently, such models are unable to represent or predict the future impacts of environmental change on flooding, sediment fluxes or river and floodplain functioning. This project will deliver a step-change in our ability to model, predict and understand how the world's large rivers are impacted by, and respond to, environmental change. We will achieve this by implementing a research strategy that involves six elements: First, we will develop a new multi-scale numerical modelling approach that enables the effects of river dynamics on environmental disturbance propagation through continental-scale drainage basins to be simulated. Second, we will develop a suite of environmental scenarios representing climate and land cover changes and dam construction throughout the Amazon Basin for the recent past (1985-2015) and future (up to 2200). Third, we will collect new field datasets at sites on the Amazon River that are required to test key components of the model. Fourth, we will work with an international team of project partners to assemble high-resolution field, satellite and model datasets that quantify channel and floodplain processes, and river morphology and dynamics throughout the Amazon Basin. Fifth, we will use these data to carry out rigorous testing of our new model. Sixth, we will apply the model to predict the future evolution of the Amazon River and its tributaries for a wide range of environmental change scenarios, and quantify the controls on hydro-geomorphic disturbance propagation within large drainage basins. We will work with our project partners to disseminate our model code, datasets and project outcomes to non-academic stakeholders, both nationally and internationally.