Responses Of Functional Groups Research Articles

The effects of grazing on flowering and fruiting phenology in South Brazilian subtropical grasslands

In subtropical grasslands, characterized by the coexistence of species with different physiology, for example C3 and C4 grasses, studies on the reproductive patterns of plants at the community level are scarce. Most available studies are limited to plant-pollinator interactions, and do not include grasses, even though knowledge on phenology of this species group is highly relevant, e.g., for grazing management or ecological restoration. In this study, we monthly evaluated flowering and fruiting in Brazilian subtropical grasslands under different grazing intensities (high, moderate, low, very low, ungrazed) over one year. To estimate the effect of the seasonal variation on the phenology of functional groups (C3 grass, C4 grass, monocots, dicots, shrubs) we used circular statistics. The highest flowering activity occurred in October and November, while fruiting peaked in March and April. Shrubs had the highest number of flowers and fruits, and C4 grasses contributed the largest number of fruiting species. The flowering peak of most functional groups occurred in October, except for C4 grasses and shrubs that peaked in February and November, respectively. Fruiting of C3 grasses peaked in December, C4 grasses and shrubs were most abundant in April and dicots, and monocots peaked in October. Grazing treatments differed considerably in flowering and fruiting patterns for all species groups. Monocots and dicots herbs showed high flowering activity under intense grazing. C3 grasses presented highest peaks in moderate and low grazing intensities, while C4 grasses peaked in very low grazing, and shrubs showed the highest peaks in ungrazed plots. Flowering and fruiting occurred throughout the year in our study system, with clear variation among functional groups in response to climatic and management patterns. Our results can guide seed collection in the field or vegetation cutting for hay transfer, and thus should lead to improvements in the ecological restoration of subtropical grasslands.

Response groups of plants from deciduous and semi-deciduous forests based on dynamic rates: evaluating impacts imposed by dams

The functional plant response groups can be useful to comprehend vegetation's reaction to an impact. The responses of tree species in seasonal forests under the influence of artificial damming were evaluated considering the hypothesis that deciduous forests may have more response groups due to their possession of species with higher tolerance to water deficit during the dry season than semi-deciduous forests, as it is an environment with greater water deficit during the dry season and possesses more species specialized in dry conditions. The hypothesis states that (1) increased water availability can hinder the maintenance and establishment of species adapted to dry environments, as they exhibit high tolerance to water deficit during dry seasons, and (2) deciduous forests will have more response groups with high demographic rates (recruitment, mortality, decrement, and increment) due to more dramatic changes in soil moisture. Response groups were detected by comparing dynamic rates of tree species near and far from the artificial lake's shore using Euclidean distance between species' dynamic rates and the Ward method. Few groups were formed away from the dams, and many groups emerged after the impact in both forests, indicating that changes resulting from damming were more prominent near the dam. More negative responses and groups affected by damming were formed in deciduous forests compared to semi-deciduous forests. Predicting the stabilization of these forests remains uncertain, necessitating long-term monitoring for obtaining robust data and additional explanations

Correction to: Dynamic changes in soil fungal communities and functional groups in response to sugarcane/soybean intercropping with reduced nitrogen fertilizer application

Correction to: Dynamic changes in soil fungal communities and functional groups in response to sugarcane/soybean intercropping with reduced nitrogen fertilizer application

Dynamic changes in soil fungal communities and functional groups in response to sugarcane/soybean intercropping with reduced nitrogen fertilizer application

Dynamic changes in soil fungal communities and functional groups in response to sugarcane/soybean intercropping with reduced nitrogen fertilizer application

A comparison of the measurement properties of the PROMIS Fatigue (MS) 8a against legacy fatigue questionnaires

BackgroundAmidst the growing number of patient-reported outcome (PRO) measures of fatigue being used in multiple sclerosis (MS) clinical trials and clinics, evidence-based consensus on the most appropriate and generalizable measures across different settings would be beneficial for clinical research and patient care. The objective of this research was to compare the validity and responsiveness of scores from the PROMIS Fatigue (MS) 8a with those of the Fatigue Severity Scale (FSS) and the Modified Fatigue Impact Scale (MFIS), across US and UK MS populations. MethodsTwo observational studies were performed in MS populations as part of a PRO measure development project, including a cross-sectional study in two tertiary US MS centers (n = 340) and a 96-week longitudinal study in the UK MS Register cohort (n = 352). In post-hoc analyses, we examined relative validity, based on ability to discriminate across patient groups with different fatigue levels or functional status at baseline (i.e., ANOVA-F PROX ÷ ANOVA-F PROMIS (MS) 8a), and relative responsiveness, based on baseline-to-Week-52 score change (effect sizes) across fatigue or functional status response groups . ResultsMean ± standard deviation (SD) age was 44.6 ± 11.3/50.0 ± 9.7; and 72.9%/77.3% were female (US/UK samples). The mean PROMIS Fatigue (MS) 8a T-score ± SD at baseline was 57.7 ± 10.5/58.9 ± 9.3 (US/UK samples). Compared with the PROMIS Fatigue (MS) 8a, relative validity (anchor: Global Health Score [GHS] fatigue global question) was 85% for MFIS symptom score, 48% for MFIS total score, and 44% for the FSS. Relative to the FSS, PROMIS Fatigue (MS) 8a scores were more sensitive to worsening (effect size = -0.43 versus -0.18) as well as improvement (effect size = 0.5 versus 0.2) in fatigue (≥1-point increase/decrease in GHS fatigue global question) over 52 weeks of follow-up. A similar pattern of score changes was observed based on a second anchor. ConclusionThe PROMIS Fatigue (MS) 8a scores showed higher responsiveness to fatigue changes than those of the FSS. The PROMIS measure also had higher precision in differentiating levels of fatigue compared to the FSS, the MFIS physical, and MFIS total scores. These differences have practical implications for the application of these questionnaires in both clinical practice and research settings (e.g., sample size estimation in clinical trials).

Plant richness, land use and temperature differently shape invertebrate leaf-chewing herbivory on plant functional groups

Higher temperatures can increase metabolic rates and carbon demands of invertebrate herbivores, which may shift leaf-chewing herbivory among plant functional groups differing in C:N (carbon:nitrogen) ratios. Biotic factors influencing herbivore species richness may modulate these temperature effects. Yet, systematic studies comparing leaf-chewing herbivory among plant functional groups in different habitats and landscapes along temperature gradients are lacking. This study was conducted on 80 plots covering large gradients of temperature, plant richness and land use in Bavaria, Germany. We investigated proportional leaf area loss by chewing invertebrates (‘herbivory’) in three plant functional groups on open herbaceous vegetation. As potential drivers, we considered local mean temperature (range 8.4–18.8 °C), multi-annual mean temperature (range 6.5–10.0 °C), local plant richness (species and family level, ranges 10–51 species, 5–25 families), adjacent habitat type (forest, grassland, arable field, settlement), proportion of grassland and landscape diversity (0.2–3 km scale). We observed differential responses of leaf-chewing herbivory among plant functional groups in response to plant richness (family level only) and habitat type, but not to grassland proportion, landscape diversity and temperature—except for multi-annual mean temperature influencing herbivory on grassland plots. Three-way interactions of plant functional group, temperature and predictors of plant richness or land use did not substantially impact herbivory. We conclude that abiotic and biotic factors can assert different effects on leaf-chewing herbivory among plant functional groups. At present, effects of plant richness and habitat type outweigh effects of temperature and landscape-scale land use on herbivory among legumes, forbs and grasses.

Effect of fire on the palatability of plants in an African woodland savanna: varying impacts depending on plant functional groups.

Fire and herbivores are two important drivers of changes in vegetation composition, quality and dynamics and both are highly related to each other. Herbivores are known to respond to fire both in terms of foraging decisions and distribution. However, little is known about the actual changes in plant chemistry following a fire event and how long these changes will last. We investigated the effect of fire on two different plant functional groups (grasses and woody species) in a woodland savanna of southern Africa. We studied chemical compounds known to be important for palatability of five perennial grass and seven woody species (trees and shrubs) common in the woodland savanna and known to be utilized by herbivores. We wanted to know if plant chemistry differs between a recently burned site (burned 2 years ago) and a control site, burned 16 years ago, and if grasses and woody species show similar relative differences between sites (i.e., the plants’ response to fire). We found a clear difference in chemical composition patterns between the plant functional groups, with an almost homogenous response to fire among woody species, but higher variability in response among grass species. Furthermore, we found that woody species maintained a higher nutritional value even 2 years after burning, whereas grasses did not show clear differences among the two investigated sites. Hence, few years after burning, woody plants might still serve as an attraction for herbivores, especially browsers, in contrast to grasses. The knowledge about these differences between the two functional groups in response to fire is beneficial for the development of management strategies for large herbivores whether domestic or wild.

Latent Variable Models Reconstruct Diversity of Neuronal Response to Drifting Gratings in Murine Visual Cortex

Decades of experimentation in visual neuroscience have been conducted with limited sample sizes of simultaneously recorded neurons. Past experiments have characterized the visual system based on statistical properties of individual neurons. Yet, no neuron functions in isolation: neural networks code information through their coordinated behavior. Calcium imaging can now simultaneously record larger populations than electrophysiological techniques could previously, allowing single-neuron analyses to be expanded to the network level. Larger datasets demand the development of computational approaches for network-level analysis. Our work validates a population modelling approach, utilizing two latent variable models and a large dataset of simultaneously recorded neurons. Rectified Latent Variable Model (RLVM) and Non-Negative Matrix Factorization (NNMF) were able to be fit to a large calcium imaging dataset without deconvolving the fluorescence signal into action potentials. These models show high reconstruction accuracy, with the RLVM outperforming NNMF. Both models’ reconstruction performance can be predicted via regression with node density and cell behavior metrics as predictors, showing that RLVM and NNMF are more effective on networks with high node density. Neurons and estimated latent variables show a spectrum of functional groups in response to simple stimulus features, with groups ranging from orientation and frequency specific, or orientation specific frequency agnostic, to orientation specific frequency modulated. Clustering of behavior profiles reveals some similar response profile groups between neurons and estimated latent variables in response to drifting gratings stimuli.

Post-synthetic 'Click' Synthesis of RAFT Polymers with Pendant Self-immolative Triazoles.

Self-immolative linkers offer efficient mechanisms for deprotecting 'caged' functional groups in response to specific stimuli. Herein we describe a convenient 'click' chemistry method for introducing pendant self-immolative linkers to a polymer backbone through post-polymerization modification. The introduced triazole rings serve both to anchor the stimuli-cleavable trigger groups to the polymer backbone, while also forming a functional part of the self-immolation cascade. We investigate the polymerization kinetics, post-synthetic modification, and self-immolation mechanism of a model polymer system, and discuss avenues for future studies on poly-pendant self-immolative triazoles as a modular, stimuli-responsive macromolecule platform.

Practical Implications of Different Phenotypic and Molecular Responses of Evergreen Conifer and Broadleaf Deciduous Forest Tree Species to Regulated Water Deficit in a Container Nursery

Recent climatic changes have resulted in an increased frequency and prolonged periods of drought and strained water resources affecting plant production. We explored the possibility of reducing irrigation in a container nursery and studied the growth responses of seedlings of four economically important forest trees: broadleaf deciduous angiosperms Fagus sylvatica L., Quercus petraea (Matt.) Liebl., and evergreen conifers Abies alba Mill. and Pinus sylvestris L. We also studied markers of water stress including modifications of biomass allocation, leaf anatomy, proline accumulation, and expression of selected genes. Growth of the broadleaved deciduous species was more sensitive to the reduced water supply than that of conifers. Remarkably, growth of the shade tolerant Abies was not affected. Adjustment of biomass allocations was strongest in P. sylvestris, with a remarkable increase in allocation to roots. In response to water deficit both deciduous species accumulated proline in leaves and produced leaves with shorter palisade cells, reduced vascular tissues, and smaller conduit diameters. These responses did not occur in conifers. Relative transcript abundance of a gene encoding the Zn-finger protein in Q. petraea and a gene encoding the pore calcium channel protein 1 in A. alba increased as water deficit increased. Our study shows major differences between functional groups in response to irrigation, with seedlings of evergreen conifers having higher tolerance than the deciduous species. This suggests that major water savings could be achieved by adjusting irrigation regime to functional group or species requirements.

Magnetite and granular activated carbon improve methanogenesis via different metabolic routes

Although supplementation of conductive materials enhances methanogenesis performance by direct interspecies electron transfer (DIET), interplay among different functional microbial groups in response to different conductive materials remains unknown. To investigate the interplay in methanogenesis, acetate-fed batch-type reactors were operated with and without conductive materials (granular activated carbon [GAC] and magnetite), and microbial community analysis and functional gene quantification were performed. Although both GAC and magnetite supplementation improved methanogenic performance, magnetite supplementation was better than GAC supplementation. The reactors supplemented with magnetite showed 31.7% more reduced lag times, 18.3% more enhanced methane production rates, and 4.9% more increased cumulative methane production, compared to those supplemented with GAC. Microbial community analysis demonstrated that DIET-related Geobacter species and their functional genes were remarkably more abundant (~49.8%) on the GAC surface, while various syntrophic acetate-oxidizing bacteria predominated on magnetite. In the quantitative analysis of functional genes expression, magnetite activated the genes of both acetate decarboxylation and CO2 reduction pathways, while GAC activated only the latter. These results imply that GAC and magnetite differently affect the routes of methanogenesis, subsequently exerting different effects on methanogenesis performance.

Analysis of niche characteristics of phytoplankton functional groups in fluvial ecosystems

Abstract Assigning species to functional response groups in phytoplankton ecology reduces the number of functional units, which helps understand the processes that shape diversity and functioning of planktonic assemblages. Although the concept has become widespread in recent years, numerical characterization of the groups’ positions in the niche space remained a challenging task. Using a large river phytoplankton dataset, we characterized the functional groups (FGs) of phytoplankton by their niche position and niche breadth in the niche space defined by the relevant environmental variables using the Outlying Main Index approach. The niche space has been defined primarily by trophic-related (nutrients) and river size-related variables (water residence time, discharge). Although we hypothesized that FGs with central niche position would have wide, while those with marginal niche position have narrow niche breadth, these have not been corroborated by the results. Rather, FGs occurred both with central niche position and intermediate breadth, as well as with marginal niche position and wide breadth. Niche position of several FGs was different from that suggested by their known habitat templates in lakes. Furthermore, we found no significant relationship between niche position and niche breadth, suggesting that the occurrence of FGs in rivers is simultaneously influenced by both niche characteristics.

Response of foliar functional traits to experimental N and P addition among overstory and understory species in a tropical secondary forest

The plasticity of morphological, physiological and developmental traits can reflect the plant adaptation to diverse environmental changes. How the foliar morphological and physiological traits with different functional groups in response to N and P fertilization is still unclear in tropical forests. Here, we employed a nine-year manipulative field experiment with nitrogen (N) and phosphorus (P) addition to investigate the foliar morphological and physiological traits as well as the N and P stoichiometry within the overstory and understory species in a tropical secondary forest of southern China. Our results showed that the N and P addition did not significantly change leaf morphological traits (leaf length, width, and ratios of length:width, leaf mass per area, LMA) in most of the studied species. The effects of N and/or P addition on leaf photosynthetic pigments were species-specific variation regardless of the overstory and understory species. However, the leaf N:P ratios of two understory species were significantly influenced by P addition while leaf N:P ratios in all overstory plants were not affected by P fertilization. Combined with the change of leaf N:P ratios under nine-year fertilization experiment, the understory plants were primarily limited by P availability, while the overstroy trees were co-limited by N and P availability in this tropical forest. Given that, we recommend that the constant leaf morphological traits of overstory and understory species in response to exogenous long-term N and P addition may be an important mechanism for adapting to low-P availability soil.

Waterbird synchrony across Australia's highly variable dryland rivers – Risks and opportunities for conservation

Understanding the mechanisms which drive large scale population dynamics of highly mobile organisms, such as birds, is as challenging as it is important. For waterbirds depending on Australia's dryland rivers, little is known about the spatiotemporal dynamics and degree of population synchrony, despite its importance for conservation theory and practice. We examined spatial synchrony in 50 waterbird species using aerial survey data over the past three decades (1983–2016), across two of Australia's largest river basins, representing almost a third of the continent using state-space models. There was broad synchrony in the responses of Australian waterbird numbers in wetlands, varying among functional response groups, reflecting the spatiotemporal mosaic of flooded wetlands across multiple scales. Ducks, the most abundant functional response group, and herbivorous waterbirds displayed strong spatiotemporal synchrony within and between the Lake Eyre Basin and Murray-Darling Basin, while synchrony of piscivores was patchier. In contrast, large waders and particularly shorebirds had poor synchronicity. While rainfall among catchments within river basins was highly correlated, streamflow was correspondingly weakly correlated in the Murray-Darling Basin primarily because river regulation had separated rainfall from flow and inundation, potentially compromising waterbird response triggers. There are clear conservation implications for wetlands and their waterbird populations, principally the protection of natural flow regimes in the Lake Eyre Basin and where needed, restoration of environmental flows in the Murray-Darling Basin. Also, management of waterbirds needs to often extend beyond the boundaries of basins.

How effective is large landscape-scale planning for reducing local weed infestations? A landscape-scale modelling approach

Finding efficient and environmentally sustainable methods for arable weed management is a current challenge in agroecosystems. Weed species disperse over scales larger than the field. Landscape-scale management could, therefore, reinforce field-scale strategies for innovative cropping systems. In particular, the introduction of semi-natural habitats, such as permanent meadows, which are unsuitable habitats for annual arable weeds, could potentially reduce weed densities in crops. We developed a spatially explicit, landscape-scale model of annual arable weed population dynamics including the main components of weed management at cropping system level: crop rotation, tillage regime, intensity of herbicide use and mechanical weeding. The variability of responses to these factors for different weed species functional types was considered by modelling four functional response groups. We used this model to investigate the effects of increasing the proportion of permanent meadows in the landscape and of the spatial arrangement of meadows on weed density in crops. With this model, increasing the proportion of permanent meadows significantly decreased mean seed density of weeds in crops. Furthermore, weed density in crops was found to be lower for landscapes in which the meadows were scattered, rather than clustered together in large zones. However, these spatial and landscape-scale effects were much weaker than the local effect of cropping systems. Weed density in permanent meadows was more sensitive to the proportion of meadows and to their spatial arrangement than weed density in crops, although the absolute value of weed density remained low in this unfavourable habitat.

Quantitative proteome profile of water deficit stress responses in eastern cottonwood (Populus deltoides) leaves.

Drought stress is a recurring feature of world climate and the single most important factor influencing agricultural yield worldwide. Plants display highly variable, species-specific responses to drought and these responses are multifaceted, requiring physiological and morphological changes influenced by genetic and molecular mechanisms. Moreover, the reproducibility of water deficit studies is very cumbersome, which significantly impedes research on drought tolerance, because how a plant responds is highly influenced by the timing, duration, and intensity of the water deficit. Despite progress in the identification of drought-related mechanisms in many plants, the molecular basis of drought resistance remains to be fully understood in trees, particularly in poplar species because their wide geographic distribution results in varying tolerances to drought. Herein, we aimed to better understand this complex phenomenon in eastern cottonwood (Populus deltoides) by performing a detailed contrast of the proteome changes between two different water deficit experiments to identify functional intersections and divergences in proteome responses. We investigated plants subjected to cyclic water deficit and compared these responses to plants subjected to prolonged acute water deficit. In total, we identified 108,012 peptide sequences across both experiments that provided insight into the quantitative state of 22,737 Populus gene models and 8,199 functional protein groups in response to drought. Together, these datasets provide the most comprehensive insight into proteome drought responses in poplar to date and a direct proteome comparison between short period dehydration shock and cyclic, post-drought re-watering. Overall, this investigation provides novel insights into drought avoidance mechanisms that are distinct from progressive drought stress. Additionally, we identified proteins that have been associated as drought-relevant in previous studies. Importantly, we highlight the RD26 transcription factor as a gene regulated at both the transcript and protein level, regardless of species and drought condition, and, thus, represents a key, universal drought marker for Populus species.

Functional richness outperforms taxonomic richness in predicting ecosystem functioning in natural phytoplankton communities

Abstract Recent studies clearly support a positive biodiversity–ecosystem functioning (BEF) relationship in phytoplankton. As taxon richness does not quantify functional diversity, functional approaches have been developed to link community functioning to diversity. Compared to terrestrial plant communities, only a few studies have validated phytoplankton functional approaches in BEF relationships. Furthermore, the ability of functional and taxonomic richness measures in predicting ecosystem functioning of natural phytoplankton communities has not been compared yet. Here, we analysed the BEF relationship using taxonomic and functional (trait categories and response groups sensu Reynolds) approaches in a broad‐scale phytoplankton dataset from Fennoscandia. First, we analysed how taxonomic and functional compositions were related to local environmental predictors. We then compared how taxonomic and functional richness performed in predicting resource‐use efficiency (the yield in phytoplankton biomass standardised by total phosphorus) as an ecosystem functioning measure. Finally, we tested whether the relationship between ecosystem functioning and taxonomic richness is further enhanced once each of the functional richness measure is also considered. Among the approaches, phytoplankton functional trait categories as community matrix showed the best correspondence with the local environment. The richness of phytoplankton response groups predicted ecosystem functioning significantly better than the taxonomic and the functional trait category richness—both in the full dataset and in almost all Fennoscandian countries. On top of taxonomic richness, only the residual variation in response group richness predicted ecosystem functioning positively in the entire dataset and in all individual countries. Applying functional approaches, reduced complexity of data should come along with reduced ecological information. We showed, however, that both functional approaches represented some functional redundancy among taxa in a meaningful way, and enhanced our ability in predicting community composition from environmental predictors. Moreover, phytoplankton response group richness sensu Reynolds summarises information on ecosystem functioning contained in the taxonomic data in a way that represents functional diversity better than the richness of functional trait categories. Interestingly, the response group approach, which is exclusively derived from field observations rather than from quantified phytoplankton traits, outperforms taxonomic richness and trait category richness in predicting ecosystem functioning in our dataset. This may highlight that our ability to quantify phytoplankton traits is still limited. Existing phytoplankton functional approaches, however, can translate the taxonomic information into a reduced but reliable functional matrix already and predict ecosystem functioning better than taxonomic data.

Soil bacteria show different tolerance ranges to an unprecedented disturbance

Soil microbial communities have remarkable capacities to cope with ceaseless environmental changes, but little is known about their adaptation potential when facing an unprecedented disturbance. We tested the effect of incremental dose of microwaving on soil bacteria as a model of unprecedented stress. 16S rRNA gene qPCR at both the DNA and cDNA levels was used to characterize the total (DNA) and transcriptionally active (cDNA) fractions of the bacterial community. Amplicon sequencing of 16S rRNA gene transcripts was performed to decipher tolerance ranges within the community using the concept of functional response groups (FRGs). Increasing microwaving doses resulted in 90% loss in total and transcriptionally active bacterial communities after 6.8 and 4.7 min, respectively. Four distinct FRGs with peculiar phylogenetic signatures were identified, revealing a link between taxonomy and increasing stress doses. FRG1, the most sensitive group, was dominated by Actinobacteria. FRG2 and FRG3, with intermediate tolerance, displayed prevalence of Proteobacteria, while FRG4, the most resistant group, was driven by Firmicutes. While the most sensitive FRGs showed predictable responses linked to changes in temperature and soil water content associated with microwaving, more tolerant FRG4 members exhibited a stochastic response nested within the Firmicutes phylum, potentially revealing bet-hedging strategists. The concept of FRGs based on 16S rRNA gene transcripts stood as an efficient tool for unraveling bacterial survival strategies and tolerance ranges triggered by incremental doses of an unprecedented stress, with regard to phylogeny linkages.

Long-term industrial metal contamination unexpectedly shaped diversity and activity response of sediment microbiome

Metal contamination poses serious biotoxicity and bioaccumulation issues, affecting both abiotic conditions and biological activity in ecosystem trophic levels, especially sediments. The MetalEurop foundry released metals directly into the French river “la Deûle” during a century, contaminating sediments with a 30-fold increase compared to upstream unpolluted areas (Férin, Sensée canal). Previous metaproteogenomic work revealed phylogenetically analogous, but functionally different microbial communities between the two locations. However, their potential activity status in situ remains unknown. The present study respectively compares the structures of both total and active fractions of sediment prokaryotic microbiomes by coupling DNA and RNA-based sequencing approaches at the polluted MetalEurop site and its upstream control. We applied the innovative ecological concept of Functional Response Groups (FRGs) to decipher the adaptive tolerance range of the communities through characterization of microbial lifestyles and strategists. The complementing use of DNA and RNA sequencing revealed indications that metals selected for mechanisms such as microbial facilitation via “public-good” providing bacteria, Horizontal Gene Transfer (HGT) and community coalescence, overall resulting in an unexpected higher microbial diversity at the polluted site.

Continental impacts of water development on waterbirds, contrasting two Australian river basins: Global implications for sustainable water use.

The world's freshwater biotas are declining in diversity, range and abundance, more than in other realms, with human appropriation of water. Despite considerable data on the distribution of dams and their hydrological effects on river systems, there are few expansive and long analyses of impacts on freshwater biota. We investigated trends in waterbird communities over 32years, (1983-2014), at three spatial scales in two similarly sized large river basins, with contrasting levels of water resource development, representing almost a third (29%) of Australia: the Murray-Darling Basin and the Lake Eyre Basin. The Murray-Darling Basin is Australia's most developed river basin (240 dams storing 29,893GL) while the Lake Eyre Basin is one of the less developed basins (1 dam storing 14GL). We compared the long-term responses of waterbird communities in the two river basins at river basin, catchment and major wetland scales. Waterbird abundances were strongly related to river flows and rainfall. For the developed Murray-Darling Basin, we identified significant long-term declines in total abundances, functional response groups (e.g., piscivores) and individual species of waterbird (n=50), associated with reductions in cumulative annual flow. These trends indicated ecosystem level changes. Contrastingly, we found no evidence of waterbird declines in the undeveloped Lake Eyre Basin. We also modelled the effects of the Australian Government buying up water rights and returning these to the riverine environment, at a substantial cost (>3.1AUD billion) which were projected to partly (18% improvement) restore waterbird abundances, but projected climate change effects could reduce these benefits considerably to only a 1% or 4% improvement, with respective annual recovery of environmental flows of 2,800GL or 3,200GL. Our unique large temporal and spatial scale analyses demonstrated severe long-term ecological impact of water resource development on prominent freshwater animals, with implications for global management of water resources.