Droughts or extended periods of low flow are but one example of extreme events that are expected to become more frequent and intense in the future due to climate change. Although each drought is unique because of its duration and magnitude as well as the type of hydrologic regime that it is interrupting, our current understanding of hydrologic, ecosystem, and species responses to drought could be improved. The intent of this session is to explore long-standing, yet unresolved questions, and work towards developing a better understanding of the drivers and responses to stream drying. We invite observational and modeling studies of the mechanisms involved in turning a stream from perennial to intermittent, as well as studies of ecological and hydrological responses to drought. Are there stream or catchment characteristics that would allow one to predict which stream segments or catchments might become intermittent, and just as importantly, which ones will recover from drought or undergo a permanent shift, as has been seen recently in south-eastern Australia? What are the consequences of stream drying and drought on ecosystem and species responses? Although many species and ecosystems have evolved to be resilient to a broad range of stressors including droughts, there is high variability in tolerance, responses, and recovery from drought. Recovery over the short and long-term will be influenced by the ongoing stressors, the legacy of prior stressors, the resiliency of the ecosystem, the adaptive capacity of biota to seasonal water stress, the connectivity of freshwater network, and the extent to which humans have created other stressors in these ecosystems. Predictions of ecological and hydrological responses to drought across stream networks and regions will be informative for anticipating responses to climate change.
For over a decade eDNA-based approaches such as DNA metabarcoding have been transforming the way we examine and assess aquatic systems. In addition to providing more comprehensive taxonomic coverage than that can be achieved by traditional, morphological methods, metabarcoding can also be used to glean information on functional processes driven by microbial communities and the stability of these communities via tools such as co-occurrence network analysis. However, eDNA-based aquatic monitoring approaches, like all other assessment methods, are not void of limitations and constraints. These range from the challenges of confidently assigning taxonomy to biases in abundance and composition. The rapidly falling costs of high-throughput sequencing and computing now makes it viable to perform eDNA surveys from hundreds of replicates targeting a range of genes and or loci. Yet to date, assessment studies for the most part have been study-specific (e.g. factorial design, or focusing correlative patterns between abiotic and biotic variables), and lack the capacity to compare the ecological integrity eDNA derived communities from different studies or across wider biogeographical zones. In contrast to traditionally obtained metrics, such as IBIs for macrofauna and fish, determining what constitutes a community of ‘good’ or ‘bad’ ecological condition or how a community should be structured as a response to a specific type of stressor (e.g. metals) remains challenging. This session will focus on methods, approaches, community ecology, and the challenges associated with upscaling eDNA based approaches for the routine monitoring of aquatic ecosystems. Presenters will discuss the latest advances, such as machine learning approaches, laboratory techniques, data analyses and bioinformatics, and ecological end-points and interpretations, with the goal of assisting and expediting the transition to both routine and broader geographical scale monitoring programs. Ultimately, this will assist in providing better approaches to improve conservation and restoration efforts and attenuate the declining global health of aquatic habitats.
Freshwater scientists and managers face a growing number of large scale ecological challenges, such as climate change, habitat fragmentation, species introductions and extirpations, and nutrient pollution, and they are addressing them using the riverscape perspective of streams and rivers (e.g., spatial and temporal hierarchies, patch dynamics and disturbance, and connectivity) and place-based approaches which integrate environmental and social perspectives (e.g., social-ecological-systems). Ecologists have laid the groundwork for spatially extensive and place-based applications of community ecology to riverscapes through developing meta-foodweb and meta-community conceptual frameworks, and advances in techniques such as eDNA, stable isotope analysis, and ‘brute force’ sampling have made such studies possible. Though there is a growing body of work characterizing food webs and communities both in relation to habitat mosaics and networks and the ways in which they shift through time, empirical studies testing meta-foodweb and community frameworks remain limited.
Through this special session we will bring together freshwater scientists who 1) develop and model theories, 2) develop and test new techniques, and 3) empirically study the foodweb and community ecology of riverscapes. Our aim is to synthesize the current and future trends of riverscape community ecology which in turn enable place-based approaches to solving large scale ecological challenges.
Panel Discussion
The magnitude, timing, and duration of flows are critical drivers of river and floodplain ecosystem structure and function. However, the flow regimes of rivers worldwide have undergone substantial changes because of water resource development, threatening the ecological integrity of river ecosystems and the services they provide to humans. Hundreds of flow experiments and monitoring programs have advanced our understanding of flow-ecology relationships but have largely been focussed on a subset of taxa (most often fish) and at small spatial scales (10s-100s metres). This creates a challenging mismatch when applying adaptive flow management to complex ecosystems at a catchment or regional scale (10s-100s kilometres). Consequently, decision makers are acting with only partial knowledge of the potential outcomes. This session aims to showcase research on the frontier of flow-ecology research that is filling these gaps in understanding for adaptive flow management. We invite work based on holistic monitoring, experimental, or modelling approaches that builds links among taxa (e.g., food webs) or examines movement of common currencies (e.g., carbon, nutrients) between ecosystems. We are also interested in research using landscape ecology concepts and/or novel technologies (e.g., drones, tagging approaches) to form an ability to predict the effects of environmental watering actions at large spatial scales and/or long temporal scales. Further, we invite work that aims to disentangle the multiple facets of current and antecedent flow patterns on physical and biological processes in rivers and floodplains. We anticipate this session will generate synthesis on the approaches that are emerging to confront the most pertinent challenges of adaptive flow management.
Panel Discussion
Panel Discussion
Panel Discussion
Panel Discussion with all Special Session Presenters
All delegates are invited to attend.
There will be a cash bar available.