Environmental controls on river assemblages at the regional scale : an application of the elements of metacommunity structure framework

Understanding factors that structure regional biodiversity is important for linking ecological and biogeographic processes. Our objective was to explore regional patterns in riverine benthic invertebrate assemblages in relation to their broad positioning along the river network and examine differences in composition, biodiversity (alpha and beta diversity), and environmental drivers. We up-scaled methods used to examine patterns in metacommunity structure (Elements of Metacommunity Structure framework) to examine faunal distribution patterns at the regional extent for 168 low-mountain stream invertebrate assemblages in central Germany. We then identified the most influential environmental factors using boosted regression trees. Faunal composition patterns were compartmentalised (Clementsian or quasi-Clementsian), with little difference from headwaters to large rivers, potentially reflecting the regional scale of the study, by crossing major catchment boundaries and incorporating different species pools. While idealised structures did not vary, environmental drivers of composition varied considerably between river sections and with alpha diversity. Prediction was substantially weaker, and the importance of space was greater, in large rivers compared to other sections suggesting a weakening in species sorting downstream. Further, there was a stronger transition in composition than for alpha diversity downstream. The stronger links with regional faunal composition than with richness further emphasises the importance of considering the alternative ways in which anthropogenic stressors are operating to affect biodiversity patterns. Our approach allowed bridging the gap between local (or metacommunity) and regional scales, providing key insights into drivers of regional biodiversity patterns

Relative influence of environmental variables in boosted regression tree models.

<p>Relative influence of each environmental variable from three categories (physical, land use and chemical) on the boosted regression tree models predicting taxonomic richness and the main axis of regional faunal composition (Metacom 1) in 168 low-mountain streams and rivers in central Germany categorised into all sites (N = 168), headwaters (N = 48), mid-sized (N = 69) and large rivers (N = 51). The top plot shows the relative influence of each individual variable and the bottom the combined influence of each category of variables. Note catchment size was removed from all size-based models (i.e. headwaters, mid-sized and large rivers). See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135450#pone.0135450.t001" target="_blank">Table 1</a> for a description of variables and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135450#pone.0135450.t003" target="_blank">Table 3</a> for the results of BRT analyses.</p

Map of study sites.

<p>Map of 168 low-mountain streams and rivers in the German state of Hessen, sampled between 2005 and 2008.</p

Results of Elements of Metacommunity Structure analysis.

<p>Results of Elements of Metacommunity Structure analysis testing for coherence, species range turnover and boundary clumping in 168 low-mountain streams in central Germany categorised into all sites (N = 168), headwaters (N = 48), mid-sized (N = 69) and large rivers (N = 51). <i>Abs</i> = number of embedded absences, <i>Re</i> = number of replacements, <i>MI</i> = Morista’s Index, SD = standard deviation. Both primary and secondary axes of organization are given. Mean and SD values are those calculated from the 1000 generated null matrices.</p><p>Results of Elements of Metacommunity Structure analysis.</p

Environmental controls on river assemblages at the regional scale: the importance of network position

<p>Talk for the 9th Symposium of European Freshwater Science, Geneva, Switzerland, 2015.</p

Diversity patterns between river sections.

<p>Diversity of benthic macroinvertebrates collected from 168 low-mountain streams and rivers in the German state of Hessen, sampled between 2005 and 2008. (a) Local taxonomic richness, (b) rarefied richness (corrected for 100 organisms), (c) Simpson’s diversity, and (d) beta diversity (beta dispersion, distance to group centroid), between headwaters (light; N = 48), mid-sized streams (medium; N = 69), and large rivers (dark; N = 51). Boxes represent the interquartile range (IQR), and whiskers are the furthest point within 1.5 x IQR above or below the IQR. Values beyond this range are plotted as individual points. Central line represents the median. Local taxonomic richness (<i>P</i> < 0.01), rarefied richness (<i>P</i> < 0.01), and Simpson’s diversity (<i>P</i> < 0.05), but not beta dispersion (<i>P</i> > 0.05) differed significantly between the three sections. See text for full results. Different letters on the plot indicate significant differences between stream sections according to Tukey’s HSD test.</p

Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro

Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO2) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO2 coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential

Expanding conservation culturomics and iEcology from terrestrial to aquatic realms

The ongoing digital revolution in the age of big data is opening new research opportunities. Culturomics and iEcology, two emerging research areas based on the analysis of online data resources, can provide novel scientific insights and inform conservation and management efforts. To date, culturomics and iEcology have been applied primarily in the terrestrial realm. Here, we advocate for expanding such applications to the aquatic realm by providing a brief overview of these new approaches and outlining key areas in which culturomics and iEcology are likely to have the highest impact, including the management of protected areas; fisheries; flagship species identification; detection and distribution of threatened, rare, and alien species; assessment of ecosystem status and anthropogenic impacts; and social impact assessment. When deployed in the right context with awareness of potential biases, culturomics and iEcology are ripe for rapid development as low-cost research approaches based on data available from digital sources, with increasingly diverse applications for aquatic ecosystems.Peer reviewe

Social equity shapes zone-selection: Balancing aquatic biodiversity conservation and ecosystem services delivery in the transboundary Danube River Basin

Freshwater biodiversity is declining, despite national and international efforts to manage and protect freshwater ecosystems. Ecosystem-based management (EBM) has been proposed as an approach that could more efficiently and adaptively balance ecological and societal needs. However, this raises the question of how social and ecological objectives can be included in an integrated management plan. Here, we present a generic model-coupling framework tailored to address this question for freshwater ecosystems, using three components: biodiversity, ecosystem services (ESS), and a spatial prioritisation that aims to balance the spatial representation of biodiversity and ESS supply and demand. We illustrate this model-coupling approach within the Danube River Basin using the spatially explicit, potential distribution of (i) 85 fish species as a surrogate for biodiversity as modelled using hierarchical Bayesian models, and (ii) four estimated ESS layers produced by the Artificial Intelligence for Ecosystem Services (ARIES) platform (with ESS supply defined as carbon storage and flood regulation, and demand specified as recreation and water use). These are then used for (iii) a joint spatial prioritisation of biodiversity and ESS employing Marxan with Zones, laying out the spatial representation of multiple management zones. Given the transboundary setting of the Danube River Basin, we also run comparative analyses including the country-level purchasing power parity (PPP)-adjusted gross domestic product (GDP) and each country's percent cover of the total basin area as potential cost factors, illustrating a scheme for balancing the share of establishing specific zones among countries. We demonstrate how emphasizing various biodiversity or ESS targets in an EBM model-coupling framework can be used to cost-effectively test various spatially explicit management options across a multi-national case study. We further discuss possible limitations, future developments, and requirements for effectively managing a balance between biodiversity and ESS supply and demand in freshwater ecosystems

Reviving Europe's rivers: Seven challenges in the implementation of the Nature Restoration Law to restore free-flowing rivers

The EU Nature Restoration Law represents an important opportunity for freshwater habitat restoration and, consequently, freshwater biodiversity protection. However, a number of challenges must be anticipated in its implementation, which may compromise its success. Some aspects, particularly those relating to freshwater ecosystems, require more clarification. We use riverine ecosystems to illustrate existing ambiguities in the proposed legislation and the potential consequences of leaving these aspects open to interpretation during the implementation process. We also discuss potential solutions to these problems which could help ensure that the law's objectives are met. We argue that river network structure and connectivity dimensions, which result into river meta-ecosystems, must be explicitly considered. For that purpose, we ask for clear definitions of the critical terms “free-flowing rivers,” “barriers,” and “reference areas.” In addition, we recommend developing methods for integrated assessment of connectivity across river networks. As a key property of river ecosystems, this must be used to prioritize actions to increase the length and number of free-flowing rivers. Adequate restoration planning at larger spatial scales will benefit from a meta-ecosystem perspective and accurate representation of aquatic-terrestrial linkages, which will significantly improve the efficacy of restoration efforts. Furthermore, stakeholder and citizen engagement offer important opportunities at local, national, and European scales, and should be fostered to ensure inclusive decision-making. The conservation challenges outlined here are particularly important for rivers, but they also have implications for other ecosystems. These considerations are useful for policymakers, conservationists, and other stakeholders involved in the Nature Restoration Law and related policy initiatives.This study was supported by the following funding sources: the MERLIN project funded under the European Commission's Horizon 2020 programme, Grant agreement No. 101036337; the DANUBE4ALL project funded by the European Union's Horizon Europe Research and Innovation Programme under grant agreement no. 101093985; the BioAgora project funded by the European Union's Horizon Europe Research and Innovation Programme under grant agreement No. 101059438; the Austrian Federal Ministry for Digital and Economic Affairs and the Christian Doppler Research Association (CD Laboratory MERI); the Austrian Science Fund (FWF) project RIMECO (I 5006); a Hungarian ANN-OTKA 141884 grant; project FLUFLUX (ERC-STG 716196); and the Leibniz Competition project “Freshwater Megafauna Futures” (P74/2018).info:eu-repo/semantics/publishedVersio