While there is an increasing recognition of the need to engage Indigenous perspectives to generate sustainable and resilient management and policy decisions, there remains a substantive gap between intent and implementation. There is an urgent need in Australia for robust approaches to engaging Indigenous knowledge to inform water management. Including Indigenous perspectives and actively engaging Indigenous people in water management is critical to generating resilient models of management and governance that provide sufficient certainty to manage agricultural and natural landscapes. Over the past two decades Indigenous people have sought greater access to water entitlements and a shift to co-design of research, informed by Indigenous research methodologies and led by Indigenous scientists. The research presented here develops and applies a methodology derived from Indigenous (Kamilaroi) ways of knowing and being to engage with Kamilaroi people to inform water management. A framework is proposed for engaging effectively with Kamilaroi specifically but is also likely to provide insights which are more generally applicable for Indigenous engagement in Australia and internationally. This methodology provides a way forward in resilient water management and planning which incorporates Indigenous knowledge, values and perspectives.

This systematic review aims at mapping current state of knowledge on the impacts of natural, anthropogenic, and climate change-induced flow variability on riverine fish and macroinvertebrates in Europe. Particular focus was placed on the effects of extreme low and high discharges, as these rare events regulate population size and taxonomic diversity. The review was conducted according to the guidelines of Collaboration for Environmental Evidence. First, evidence was searched for in 1) academic repositories, 2) specialist websites (e.g. limnological associations), 3) Google Scholar, as well as through 4) direct contact with specialists and 5) open call for evidence. Thus, the search covered both primary and grey literature. No date, language, or document type restrictions were applied. All studies were screened in two steps: title and abstract, and full-text. The eligibility criteria included: geographical scope, population, exposure/intervention, outcome and comparator. Geographically, the map covered freshwater ecoregion of Central and Western Europe. Eligible populations included fish and macroinvertebrates (both native and introduced) of temperate floodplain rivers. Flow variability included (1) anthropogenic causes; (2) natural causes; or (3) climate change. Outcome metrics such as abundance, richness, diversity, growth, migration, reproduction, survival, or biomonitoring indices, were considered relevant. The comparators of BACI (Before/After, Control/Impact) design, or temporal or spatial trends were considered eligible. The included studies were carefully scrutinized to extract such details as location, timespan, sampling methods, etc. and to create a searchable database on flow-biota studies in the region. The resulting dataset was further analysed to identify knowledge clusters and knowledge gaps.

In the European Union, river managers and authorities are facing the challenge of the transition from minimum flows to ecological flows, i.e., from flows sufficient to maintain aquatic species during crucial low-flow periods to flows consistent with the achievement of the good ecological status sensu Water Framework Directive. In order to evaluate the suitability of the current management practices and protection measures, we investigated a river reach of the lowland Ticino River, the second Italian river in terms of average flow. The study reach is located downstream of an intake structure, capable of maximum diversion of approximately 60% of the river mean annual discharge, for agriculture and hydropower. We first monitored benthic macroinvertebrate community during low-flow periods and quantified the ecological status based on this biological quality element. Then, we applied eco-hydraulic modelling to assess habitat availability for different aquatic organisms at the currently adopted ecological flows. We selected two fish species, marble trout (Salmo marmoratus), the only salmonid species of this river even if locally extinct in recent years, and Padanian barbel (Barbus plebejus), a cyprinid species sensitive to environmental pressures and currently threatened also by the invasion by the congeneric European barbel (Barbus barbus). Moreover, we set-up habitat suitability curves for benthic macroinvertebrate taxa representative of the Ticino community, and used them for modelling their habitat. The results of the two approaches support a thorough assessment of the efficacy of ecological flows for the protection of freshwater ecosystems in regulated rivers.

Human activities have had unprecedented effects on diversity, productivity, and their relationships in rivers over the past decades. While numerous studies have examined the alteration of diversity and productivity independently, less is known about the extent and direction of change in the diversity-productivity relationships and the key drivers that influence them. One of the unique study on this issue suggests that this relationship highly depends on the disturbance regime of the ecosystem. Therefore, considering the homogenization of seasonal and inter-annual streamflow caused by dams, we hypothesize that dams will disrupt the diversity-productivity relationship downstream by causing significant changes in the composition of freshwater communities. In this study, we used a control-impact design that covered 19 sites in northern Spain to test our hypothesis.
The results showed consistent patterns of change in the composition of all taxonomic groups, from prokaryotes and primary producers to secondary producers. Primary productivity exhibited a direct and positive relationship with the diversity of primary producers in control sites, which were characterized by high variability and unpredictable streamflow. In contrast, this relationship was non-existent or negative in altered reaches, which were characterized by homogenized and more stable flow conditions. This pattern observed for primary producers was consistent in different biological groups throughout the food web, as an increase in primary productivity also increased the diversity of the other eukaryotic groups. Our study also revealed that inter-annual variability (hydrological year or precipitation related events) has substantial impacts on stream ecosystem metabolism rates.

We conducted a 2-year study (2020-2021) on the aquatic foodweb in the Glen Canyon reach of the Colorado River, the sixth-longest US river with a drainage area of 673,000 km2. One of the nation’s largest hydroelectric dams is situated in Glen Canyon and until recently was run as a hydropeaking facility, creating turbulent flow similar to mountain rivers in the region. In 2014, flow was reduced to produce power while protecting the Grand Canyon downstream, creating a relatively stable flow in tailwaters. The macrophyte assemblage during turbulent flow (1970s-1990s) was dominated by the green alga Cladophora glomerata colonizing cobbles and boulders, with epiphytic diatoms as the primary foodbase for invertebrate consumers and fish. Under present flow conditions, we document major biotic shifts on sand and rock substrata: a dense aquatic meadow of Fontinalis hypnoides, Chara vulgaris, Potamogeton spp., Zanichellia palustris, and Cladophora. Significantly different physical conditions may also have led a change in the epiphytic diatom flora. Of 218 subgeneric taxa identified in 2020, approximately 53% had not previously been recorded during turbulent-flow conditions, including extensive mucilage-producing species Cymbella mexicana and Didymosphenia geminata. Benthic algal production in 2021 peaked early in spring and declined sharply by summer, corresponding with algal nutrient stoichiometry (C:P ratios) shifting rapidly from phosphorus-sufficient (120 +/- 15) in May to P-limited (630 to 680) ratios in June-July. Algal production may also have been limited by a summer peak of New Zealand mudsnails (Potamopyrgus antipodarum). Efforts are underway to examine invertebrate gut contents to assess grazing impacts.

Accelerating the design and implementation of environmental flows (e-flows) is essential to curb the rapid, ongoing loss of freshwater biodiversity and the benefits it provides to people. E-flow assessments have historically relied on ensuring minimum instream flows for individual rivers below dams, but recent decades have witnessed a shift to e-flow standards encompassing multiple aspects of the flow regime and developed at the regional scale rather than on a river-by-river basis. Nonetheless, regional e-flow planning remains focused on species’ responses to the local flow regime. This singular focus overlooks recent advances in metasystem ecology which demonstrate that biodiversity and ecosystem functioning in river networks result from the interplay of local (abiotic conditions and biotic interactions) and regional (dispersal) processes. E-flow prescriptions may thus be less effective, for example, when the population and community dynamics within a river are strongly driven by species dispersal. No guidelines currently exist to account for these processes in designing e-flows. We address this gap by first illustrating how metasystem processes mediate ecological responses to flow. We then provide a step-by-step operational framework of how e-flows can be designed to conserve or restore metasystem dynamics, from defining the ecological targets of the e-flows program to designing, implementing, and monitoring e-flows. Our recommendations are relevant to diverse regulatory contexts and can improve e-flow outcomes even in basins with limited in-situ data.

Environmental flows methods and implementation have continued to actively evolve through researchers and practitioners alike in the direction of whole systems thinking and trans-disciplinarity. In particular, the gradual meaningful inclusion of social, cultural, and spiritual considerations to the extent that the current internationally accepted definition of environmental flows now makes explicit reference to such factors and their critical links to the sustainability and health of freshwater ecosystems. This is also reflected in the increasing research emphasis within the field on social and cultural connections and interdependencies from different perspectives and worldviews. Viewing space and connections across different knowledge systems can build a stronger foundation through exchanging stories, perspectives and ideas and can lead to connections with communities and strengthen our understanding of a system. Despite this trend towards working with broader perspectives across different knowledge systems, there is still a strong Western science focus, practice and thinking, both methodologically and in terms of implementation. Braiding and weaving of knowledge systems are increasingly used as ways to bridge different our understanding while maintaining the integrity of each respective knowledge system and enabling the reciprocal exchange of understanding for mutual learning. Here we explore a potential pathway for change through ongoing dialogue with examples of environmental flows studies from across Canada.