On the use of multicriteria decision analysis to formally integrate community values into ecosystem‐based freshwater management

Freshwater ecosystems are essential to peoples' economic, cultural, and social well-being, yet are still among the most threatened ecosystems on the planet. Consequently, a plethora of recent regulations and policies seek to halt the loss of restore or safeguard freshwaters, their biodiversity, and the ecosystem services they provide. Ecosystem-based management (EBM), an approach that considers human society as an integral part of ecosystems, is increasingly being promoted to help meet this challenge. EBM involves an overarching regulatory framework and local solutions with trade-offs and compromises factors that not only make decision processes complex but also provide the means for combining top down regulation with bottom-up priorities into collaborative management strategies. Although stakeholder participation is encouraged in most modern freshwater management, community values are often largely neglected. Here, we introduce a well-known participatory decision support framework based on multicriteria decision analysis (MCDA) to operationalize EBM and promote community-inclusive decision making in freshwater management. We explain the different steps that this approach comprises, which lead to the prioritization of a management strategy in a collaborative way. We also show how cultural values that inherently embed strong links between the environment and people can be used together with typical ecological and socio-economic values. We illustrate the MCDA-based EBM-approach for New Zealand, one of the few countries in which regional freshwater management is mandated to uphold environmental quality standards, while safeguarding local community values and ecosystem services. Finally, we discuss some of the challenges, which are increasingly emerging as a result of mandated community collaboration in environmental management. © 2018 John Wiley & Sons, Ltd.Simone Langhans has received funding from the European Unio

The role of timing, duration, and frequency of inundation in controlling leaf litter decomposition in a river-floodplain ecosystem (Tagliamento, northeastern Italy)

Despite growing recognition of the importance of a natural flow regime in river-floodplain systems, researchers struggle to quantify ecosystem responses to altered hydrological regimes. How do frequency, timing, and duration of inundation affect fundamental ecosystem processes such as leaf litter decomposition? Along the semi-natural Tagliamento River corridor, located in northeastern Italy, we employed in situ experiments to separate effects of different inundation components on breakdown rates of black poplar (Populus nigra). We used a litter-bag method with two different mesh sizes to investigate how fungi and macroinvertebrates influence leaf breakdown rates. Ten treatments, each representing a specific combination of duration and frequency of inundation, were deployed in two seasons (summer, winter) to mimic complex inundation patterns. After 30days of exposure, mean percentage of remaining leaf litter (ash free dry mass) ranged between 51% (permanent wet) and 88% (permanent dry). Leaf breakdown was significantly faster in winter than in summer. Duration of inundation was the main inundation component that controlled leaf breakdown rates. Leaf-shredding macroinvertebrates played only a role in the permanent wet treatment. Fungal parameters explained the faster leaf breakdown in winter. Our study suggests that modifications of the inundation regime will directly modify established decomposition processes. Factors reducing duration of inundation will decelerate leaf breakdown rates, whereas a decrease in flow variation will reduce leaf breakdown heterogeneit

Edge Effects Are Important in Supporting Beetle Biodiversity in a Gravel-Bed River Floodplain

Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge effects. In this study, we investigated the abundance, composition, richness, and conservation status of beetle assemblages at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60–100 m, and 5 m within the riparian forest), and time of the year (February–November) across a 200 m-wide gravel bar at the near-natural Tagliamento River (Italy), to detect edge effects in four floodplain ecotones: aquatic-terrestrial, forest-active floodplain, sediment-air, and sediment- groundwater. We used conventional pitfall traps and novel tube traps to sample beetles comparably on the sediment surface and within the unsaturated sediments. We found a total of 308 beetle species (including 87 of conservation concern) that showed multiple, significant positive edge effects across the floodplain ecotones, mainly driven by spatial heterogeneity: Total and red list beetle abundance and richness peaked on the sediment surface, at channel margins, and at the edge of the riparian forest. All ecotones possessed edge/habitat specialists. Most red list species occurred on the sediment surface, including five species previously considered extinct – yet two of these species occurred in higher densities in the unsaturated sediments. Conservation and management efforts along gravel-bed rivers must therefore promote a dynamic flow and sediment regime to create and maintain habitat heterogeneity and ecotone diversity, which support a unique and high biodiversity

Is the unsaturated sediment a neglected habitat for riparian arthropods? Evidence from a large gravel-bed river

AbstractDespite exposed surface sediments of braided, gravel-bed rivers host a diverse and endangered arthropod fauna, the ecology of the unsaturated layers below the surface but above the groundwater is mostly unexplored. Even if only parts of this zone are accessible to arthropods, this could be the most extensive habitat along braided rivers with likely important functions for arthropods’ population dynamics. Across a 200 m-wide gravel bar at the Tagliamento River (Italy), we investigated the abundance, taxon richness, and composition of arthropods at varying sediment depth (0, 0.1, 0.6 and 1.1 m), distance from the channel (1, 5, 20, and 60–100 m), and time of the year (February–November). We used conventional pitfall traps and novel tube traps to sample surface and subsurface sediments comparably. Although abundance and diversity hotspots were located at the sediment surface at the edge of the gravel bar, the subsurface sediments supported an abundant arthropod fauna with similar richness to the sediment surface. We demonstrate that arthropods inhabit unsaturated sediments throughout the year, and speculate on the zone’s role as refugium and/or partial habitat. To ensure the future of this dynamic and diverse habitat we urge science, conservation, and management to include it in future programmes

Leaf-decomposition heterogeneity across a riverine floodplain mosaic

Abstract.: Riverine floodplains are a mosaic of aquatic, semi-aquatic and terrestrial habitats. While spatially distinct, these habitats are well connected by flows of carbon and nutrients, often in the form of leaf litter, and thus the ecological processes occurring in one habitat have ramifications for others. The aim of this study was to compare leaf decomposition, a key process in riverine ecosystems, across diverse floodplain-habitat types and to assess the role of leaf-shredding detritivores and fungi. Black poplar, Populus nigra L., leaves were exposed in seven contrasting habitat types (total of 28 sites) on the floodplain of the Tagliamento River (NE-Italy). Three distinct classes of decomposition rates emerged, corresponding to sites in the river channel (fast), terrestrial sites (slow), and ponds (intermediate). In the river channel and in ponds, leaf decomposition was driven by both microbial and detritivore activity, as evidenced by differences in coarse- and fine-mesh bags, which respectively allowed and prevented access to the leaves by leaf-consuming detritivores. Additionally, we cannot rule out that decomposition in the channel was also promoted by physical abrasion and/or fragmentation. In terrestrial floodplain habitats, very little plant litter was utilized, and leaching of soluble compounds appeared to be the primary process responsible for leaf-mass loss. Our results demonstrate that the wide range of habitats of braided floodplain rivers can have diverse decomposition potentials, creating spatial variability in both the rates of decomposition and its causes. Alterations to the natural flow regime (e.g., water abstraction, or retention by dams) and morphological changes (e.g., channelization) strongly reduce habitat diversity. These impacts will likely reduce the heterogeneity in decomposition rates across floodplains of braided rivers, with unknown consequences for overall functioning of floodplain ecosystem

The terrestrial and semi-aquatic invertebrates of intermittent rivers and ephemeral streams

Intermittent rivers and ephemeral streams (IRES), which cease flow and/or dry at some point, are the most abundant waterways on earth, and are found on every continent. They can support a diverse, and often abundant, terrestrial and semi‐aquatic invertebrate (TSAI) fauna, which has been poorly explored due to its position at the fringe between aquatic and terrestrial disciplines. TSAIs can inhabit a variety of habitat types, including the shoreline, the surface of exposed gravel bars, unsaturated gravels, dry riverbeds, riparian zones, and floodplains. Much less is known about the species composition and ecological roles of TSAIs of IRES than their aquatic counterparts, with TSAIs being largely overlooked in conceptual models, legislation, policy, and ecological monitoring. Herein we review the TSAI literature that has increased substantially over the last decade and present conceptual models describing how TSAIs respond to hydrological changes in IRES. Then, we test these models with data collected during wet and dry phases in IRES from Australia and France. These generic models can be utilised by water managers and policy makers, ensuring that both wet and dry phases are considered in the management and protection of IRES. IRES should be viewed as a habitat continuum through time, with taxa from a pool of aquatic, semi‐aquatic and terrestrial invertebrates inhabiting at any hydrological stage. We call for collaboration among terrestrial and aquatic ecologists to explore these invertebrates and ecosystems further

More exposure opportunities for promoting freshwater conservation

Freshwater ecosystems have a higher percentage of threatened and extinct species than terrestrial or marine realms, but remain under‐represented in conservation research and actions arguably as a consequence of less popularity and promotion. Cover images of conservation journals were used as a proxy of exposure and potential promotion opportunities provided for different ecosystems and species. To examine whether articles related to cover images received more attention, citations and Altmetric scores of cover‐featured articles were compared with non‐featured ones within the same host journal issue. Freshwater ecosystems (10.4%) were featured less often than marine (15.2%) or terrestrial (74.4%) ecosystems on covers of 18 conservation journals from 1997 to 2016. All 15 most featured species are from terrestrial or marine ecosystems. In addition, cover‐featured studies showed higher citations and Altmetric scores than non‐featured ones within the same host journal issue, indicating that cover‐featured articles received more attention. Further investigations are needed to examine the relationship (i.e. whether there is a true causality) between being featured on the cover, and citations and Altmetric scores received by articles, as well as potentially resulting in greater conservation efforts. Nevertheless, we believe that providing exposure opportunities is likely to better inform the public about the continuing degradation of freshwater ecosystems and its impacts on human well‐being, including economic loss and danger to public health. Journal editors can contribute by balancing their selection of featured ecosystems and species when opportunities arise. Increasing exposure opportunities for freshwater ecosystems through various channels seems a promising approach to raise public awareness and appreciation of freshwater biodiversity. Scientists can play an active role and form an alliance with journal editors, conservation organizations, and media, to increase momentum in society for fresh waters to be experienced as essential ecosystems and prevent further degradation of freshwater habitats and biodiversity loss.Education, Audiovisual and Culture Executive Agency of the European Union: Erasmus Mundus Joint Doctorate SMART http://dx.doi.org/10.13039/501100000785Leibniz Association: Freshwater Megafauna Futures http://dx.doi.org/10.13039/501100001664Spanish Government’s María de Maeztu excellence accreditation 2018‐2022German Federal Ministry of Education and Research (BMBF)Peer Reviewe

More exposure opportunities for promoting freshwater conservation

1. Freshwater ecosystems have a higher percentage of threatened and extinct species than terrestrial or marine realms, but remain under-represented in conservation research and actions arguably as a consequence of less popularity and promotion. 2. Cover images of conservation journals were used as a proxy of exposure and potential promotion opportunities provided for different ecosystems and species. To examine whether articles related to cover images received more attention, citations and Altmetric scores of cover-featured articles were compared with non-featured ones within the same host journal issue. 3. Freshwater ecosystems (10.4%) were featured less often than marine (15.2%) or terrestrial (74.4%) ecosystems on covers of 18 conservation journals from 1997 to 2016. All 15 most featured species are from terrestrial or marine ecosystems. 4. In addition, cover-featured studies showed higher citations and Altmetric scores than non-featured ones within the same host journal issue, indicating that cover-featured articles received more attention. Further investigations are needed to examine the relationship (i.e. whether there is a true causality) between being featured on the cover, and citations and Altmetric scores received by articles, as well as potentially resulting in greater conservation efforts. Nevertheless, we believe that providing exposure opportunities is likely to better inform the public about the continuing degradation of freshwater ecosystems and its impacts on human well-being, including economic loss and danger to public health. Journal editors can contribute by balancing their selection of featured ecosystems and species when opportunities arise. 5. Increasing exposure opportunities for freshwater ecosystems through various channels seems a promising approach to raise public awareness and appreciation of freshwater biodiversity. Scientists can play an active role and form an alliance with journal editors, conservation organizations, and media, to increase momentum in society for fresh waters to be experienced as essential ecosystems and prevent further degradation of freshwater habitats and biodiversity loss

Environmental heterogeneity affects input, storage, and transformation of coarse particulate organic matter in a floodplain mosaic

Quantifying spatial and temporal dynamics of organic matter (OM) is critical both for understanding ecosystem functioning and for predicting impacts of landscape change. To determine the influence of different habitats and coarse particulate OM (CPOM) types upon floodplain OM dynamics, we quantified aerial input, lateral surface transfer, and surface storage of CPOM over an annual cycle on the near-natural floodplain of the River Tagliamento in NE-Italy. Using these data, we modelled floodplain leaf dynamics, taking account of the spatial distribution and hydrologic connectivity of habitats, and using leaf storage as a response variable. Mean aerial CPOM input to the floodplain was similar from riparian forest and islands, but surface transfer was greater from islands, supporting the suggestion that these habitats act as "islands of fertility” along braided rivers. Leaves were the lateral conveyor of energy to more open parts of the floodplain, whereas CPOM was mainly stored as small wood in vegetated islands and riparian forest. Simulating the loss of habitat diversity (islands, ponds) decreased leaf storage on the whole floodplain, on exposed gravel and in large wood accumulations. In contrast, damming (loss of islands, ponds and floods plus floodplain overgrowth) greatly increased storage on exposed gravel. A random shuffle of habitats led to a storage increase on exposed gravel, while that in large wood accumulations and ponds declined. These results disentangle some of the complexities of CPOM dynamics in floodplain ecosystems, illustrate the value of models in understanding ecosystem functioning at a landscape level, and directly inform river management practic