Integral strategy for evaluation of fecal indicator performance in bird-influenced saline inland waters

Wild birds are an important nonpoint source of fecal contamination of surface waters, but their contribution to fecal pollution is mostly difficult to estimate. Thus, to evaluate the relation between feces production and input of fecal indicator bacteria (FIB) into aquatic environments by wild waterfowl, we introduced a new holistic approach for evaluating the performance of FIB in six shallow saline habitats. For this, we monitored bird abundance, fecal pellet production, and the abundance of FIB concomitantly with a set of environmental variables over a 9-month period. For estimating fecal pellet production, a new protocol of fecal pellet counting was introduced, which was called fecal taxation (FTX). We could show that, over the whole range of investigated habitats, bird abundance, FTX values, and FIB abundance were highly significantly correlated and could demonstrate the good applicability of the FTX as a meaningful surrogate parameter for recent bird abundances and fecal contamination by birds in shallow aquatic ecosystems. Presumptive enterococci (ENT) were an excellent surrogate parameter of recent fecal contamination in these saline environments for samples collected at biweekly to monthly sampling intervals while presumptive Escherichia coli and fecal coliforms (FC) were often undetectable. Significant negative correlations with salinity indicated that E. coli and FC survival was hampered by osmotic stress. Statistical analyses further revealed that fecal pollution-associated parameters represented one system component independent from other environmental variables and that, besides feces production, rainfall, total suspended solids (direct), and trophy (indirect) had significant positive effects on ENT concentrations. Our holistic approach of linking bird abundance, feces production, and FIB detection with environmental variables may serve as a powerful model for application to other aquatic ecosystems.     

In shallow water ecosytems the abiotic environment is more important than prey abundance for foraging terns

Shallow freshwater aquatic ecosystems are discrete feeding patches for fish eating birds. A unique feature of these ecosystems is that their physical conditions can change dramatically in a short period of time, particularly temperature, turbidity, and dissolved oxygen. Based on previous research we predicted that increasing turbidity will reduce the availability of fish to birds due to reduced visibility, while increasing temperature and decreasing dissolved oxygen will increase their availability through increases in activity and movement towards the more oxygenated surface areas, respectively. We also predicted that overall abundance of fish should increase feeding activity by terns. We measured these environmental variables, bird activity, and fish abundance from May to August from 2006 to 2008 in a marsh in southern Manitoba, Canada. Our results showed that only variation in dissolved oxygen levels affected feeding activity by terns. Since there was no relationship between bird and fish abundance either within or among years, these results suggest that it is the availability of prey (i.e. the upward movement of fish into the water column) and not their abundance per se that influences the number of avian predators present and hence the risk of predation to fish. These data demonstrate how the physical environment of aquatic ecosystems can impact terrestrial avian predators, and the link that exists between the physical environment and predator-prey interactions.     

Enterococci in the Environment

Summary: Enterococci are common, commensal members of gut communities in mammals and birds, yet they are also opportunistic pathogens that cause millions of human and animal infections annually. Because they are shed in human and animal feces, are readily culturable, and predict human health risks from exposure to polluted recreational waters, they are used as surrogates for waterborne pathogens and as fecal indicator bacteria (FIB) in research and in water quality testing throughout the world. Evidence from several decades of research demonstrates, however, that enterococci may be present in high densities in the absence of obvious fecal sources and that environmental reservoirs of these FIB are important sources and sinks, with the potential to impact water quality. This review focuses on the distribution and microbial ecology of enterococci in environmental (secondary) habitats, including the effect of environmental stressors; an outline of their known and apparent sources, sinks, and fluxes; and an overview of the use of enterococci as FIB. Finally, the significance of emerging methodologies, such as microbial source tracking (MST) and empirical predictive models, as tools in water quality monitoring is addressed. The mounting evidence for widespread extraenteric sources and reservoirs of enterococci demonstrates the versatility of the genus Enterococcus and argues for the necessity of a better understanding of their ecology in natural environments, as well as their roles as opportunistic pathogens and indicators of human pathogens.     

Microsporidian Species Known To Infect Humans Are Present in Aquatic Birds: Implications for Transmission via Water?

Human microsporidiosis, a serious disease of immunocompetent and immunosuppressed people, can be due to zoonotic and environmental transmission of microsporidian spores. A survey utilizing conventional and molecular techniques for examining feces from 570 free-ranging, captive, and livestock birds demonstrated that 21 animals shed microsporidian spores of species known to infect humans, including Encephalitozoon hellem (20 birds; 3.5%) and Encephalitozoon intestinalis (1 bird; 0.2%). Of 11 avian species that shed E. hellem and E. intestinalis, 8 were aquatic birds (i.e., common waterfowl). The prevalence of microsporidian infections in waterfowl (8.6%) was significantly higher than the prevalence of microsporidian infections in other birds (1.1%) (P < 0.03); waterfowl fecal droppings contained significantly more spores (mean, 3.6 × 10⁵ spores/g) than nonaquatic bird droppings contained (mean, 4.4 × 10⁴ spores/g) (P < 0.003); and the presence of microsporidian spores of species known to infect humans in fecal samples was statistically associated with the aquatic status of the avian host (P < 0.001). We demonstrated that a single visit of a waterfowl flock can introduce into the surface water approximately 9.1 × 10⁸ microsporidian spores of species known to infect humans. Our findings demonstrate that waterborne microsporidian spores of species that infect people can originate from common waterfowl, which usually occur in large numbers and have unlimited access to surface waters, including waters used for production of drinking water.     

Microsporidian species known to infect humans are present in aquatic birds: implications for transmission via water?

Human microsporidiosis, a serious disease of immunocompetent and immunosuppressed people, can be due to zoonotic and environmental transmission of microsporidian spores. A survey utilizing conventional and molecular techniques for examining feces from 570 free-ranging, captive, and livestock birds demonstrated that 21 animals shed microsporidian spores of species known to infect humans, including Encephalitozoon hellem (20 birds; 3.5%) and Encephalitozoon intestinalis (1 bird; 0.2%). Of 11 avian species that shed E. hellem and E. intestinalis, 8 were aquatic birds (i.e., common waterfowl). The prevalence of microsporidian infections in waterfowl (8.6%) was significantly higher than the prevalence of microsporidian infections in other birds (1.1%) (P < 0.03); waterfowl fecal droppings contained significantly more spores (mean, 3.6 x 10(5) spores/g) than nonaquatic bird droppings contained (mean, 4.4 x 10(4) spores/g) (P < 0.003); and the presence of microsporidian spores of species known to infect humans in fecal samples was statistically associated with the aquatic status of the avian host (P < 0.001). We demonstrated that a single visit of a waterfowl flock can introduce into the surface water approximately 9.1 x 10(8) microsporidian spores of species known to infect humans. Our findings demonstrate that waterborne microsporidian spores of species that infect people can originate from common waterfowl, which usually occur in large numbers and have unlimited access to surface waters, including waters used for production of drinking water.     

An effective method for ecosystem‐scale manipulation of bird abundance and species richness

Manipulation experiments are a cornerstone of ecological research, but can be logistically challenging to execute—particularly when they are intended to isolate the ecological role of large, vagile species, like birds. Despite indirect evidence that birds are influential in many ecosystems, large‐scale, multi‐year bird manipulation experiments are rare. When these studies are conducted, they are typically realized with caged or netted exclosures, an approach that can be expensive, risky for wildlife, and difficult to maintain. In cases where caged exclosures are not appropriate, alternate approaches are needed to allow rigorous empirical studies on the ecological role of birds. Here, we present and validate a method for experimentally increasing the abundance and richness of birds at the scale of entire aquatic ecosystems. Unlike bird exclusion, this approach is experimentally tractable, appealing to land managers, and possible to deploy over large spatial scales. We tested the efficacy of our approach for increasing bird abundance and species richness at 16 central California ponds. Based on bird visitation data obtained by summer camera trapping, our approach significantly increased bird species richness and abundance at manipulated ponds compared to control ponds. Attractant treatments mitigated the negative effects of a major drought on bird species richness and generated a near doubling of bird abundance in the presence of attractants. Treatments had no effect on most mammal species, with the exception of ground squirrels, which increased in abundance in the presence of attractants. These results suggest that attractants are effective in increasing bird abundance and richness. We encourage researchers to consider this approach for experimentally isolating the ecological role of birds in aquatic and open terrestrial ecosystems, especially in cases where cost or logistical constraints preclude the use of caged or netted exclosures.     

Winter predation by insectivorous birds and consequences for arthropods and plants in summer

Top-down effects of predators can have important consequences for ecosystems. Insectivorous birds frequently have strong predation effects on herbivores and other arthropods, as well as indirect effects on herbivores’ host plants. Diet studies have shown that birds in temperate ecosystems consume arthropods in winter as well as in summer, but experimental studies of bird predation effects have not attempted to quantitatively separate winter predation impacts from those in summer. To understand if winter foraging by insectivorous birds has consequences for arthropods or plants, we performed a meta-analysis of published bird exclusion studies in temperate forest and shrubland habitats. We categorized 85 studies from 41 publications by whether birds were excluded year-round or only in summer, and analyzed arthropod and plant response variables. We also performed a manipulative field experiment in which we used a factorial design to exclude birds from Quercus velutina Lam. saplings in winter and summer, and censused arthropods and herbivore damage in the following growing season. In the meta-analysis, birds had stronger negative effects on herbivores in studies that included winter exclusion, and this effect was not due to study duration. However, this greater predation effect did not translate to a greater impact on plant damage or growth. In the field experiment, winter exclusion did not influence herbivore abundance or their impacts on plants. We have shown that winter feeding by temperate insectivorous birds can have important consequences for insect herbivore populations, but the strength of these effects may vary considerably among ecosystems. A full understanding of the ecological roles of insectivorous birds will require explicit consideration of their foraging in the non-growing season, and we make recommendations for how future studies can address this.     

Phylogenetic diversity and molecular detection of bacteria in gull feces

In spite of increasing public health concerns about the potential risks associated with swimming in waters contaminated with waterfowl feces, little is known about the composition of the gut microbial community of aquatic birds. To address this, a gull 16S rRNA gene clone library was developed and analyzed to determine the identities of fecal bacteria. Analysis of 282 16S rRNA gene clones demonstrated that the gull gut bacterial community is mostly composed of populations closely related to Bacilli (37%), Clostridia (17%), Gammaproteobacteria (11%), and Bacteriodetes (1%). Interestingly, a considerable number of sequences (i.e., 26%) were closely related to Catellicoccus marimammalium, a gram-positive, catalase-negative bacterium. To determine the occurrence of C. marimammalium in waterfowl, species-specific 16S rRNA gene PCR and real-time assays were developed and used to test fecal DNA extracts from different bird (n = 13) and mammal (n = 26) species. The results showed that both assays were specific to gull fecal DNA and that C. marimammalium was present in gull fecal samples collected from the five locations in North America (California, Georgia, Ohio, Wisconsin, and Toronto, Canada) tested. Additionally, 48 DNA extracts from waters collected from six sites in southern California, Great Lakes in Michigan, Lake Erie in Ohio, and Lake Ontario in Canada presumed to be impacted with gull feces were positive by the C. marimammalium assay. Due to the widespread presence of this species in gulls and environmental waters contaminated with gull feces, targeting this bacterial species might be useful for detecting gull fecal contamination in waterfowl-impacted waters.     

Effects of intensive rice production practices on avian biodiversity in Southeast Asian managed wetlands

Rice fields are common throughout the agricultural landscape of Southeast Asia and sustain various bird species. These birds can provide ecosystem services, such as pest control, that improve agricultural yields whilst minimising the use of agrochemicals. This study quantified avian biodiversity in rice production landscapes during three farming stages in Peninsular Malaysia. In Malaysia, rice fields can be an important habitat for migrating birds due to Malaysia’s position on the East-Asian–Australasian Flyway. We determined bird abundance, species richness, and composition in rice field landscapes and compared these during different stages of rice growing. Wetland and terrestrial birds were counted in rice fields using the point-count method. Sixty sampling points were randomly established in three locations, from which 3447 individual birds of 46 species and 26 families were recorded. There was a significant difference in total bird abundance and species richness between the three different stages of rice growing. The growing stage supported greater bird abundance and species richness compared to the pre-harvest and post-harvest stages. Rice-growing provides temporary habitats to different bird species in this managed aquatic landscape. This implies the presence of abundant food, such as small fish and amphibians. The evidence from this study suggests that biodiversity-friendly agricultural practices should be implemented to improve habitat quality for birds in rice production landscapes.     

Large-scale features affect spatial variation in seed dispersal by birds in juniper woodlands

Fruit–frugivore interactions have received great attention from evolutionary, ecological and applied perspectives. However, despite the fact that large-scale approaches may offer new insights on fruit–frugivore interactions, little work has been devoted to exploring the factors shaping large-scale variation of seed dispersal. This paper studies the spatial variation in seeds regurgitated within pellets by wintering thrushes (genusTurdus) in a set of 26 Spanish juniper (Juniperus thurifera) woodlands scattered along a latitudinal gradient during two winters of contrasting cone and bird abundance. It explicitly explores whether pellet rain variation among woodlands was related to changes in vegetation cover, temperature, day length duration and bird abundance. Top regression models in the Akaike information criterion framework explained 34 % and 70 % of variance in pellet numbers in low and high crop and bird abundance years, respectively. In both winters, the spatial variation in pellets correlated to thrush abundance and day length duration. Pellet abundance linked to cone distribution only in the year of high crop, in which many migratory, extra-Iberian thrushes arrived to exploit the resource. Strong dependence of seed dispersion on large-scale features affecting bird numbers (e.g. the arrival of extra-Iberian migratory birds) and feeding behaviour (e.g. latitudinal variation in day length duration) suggests a primary role for variables acting at large scale on this mutualistic interaction.     

Intertidal habitat utilization patterns of birds in a Northeast Pacific estuary

A habitat-based framework is a practical method for developing models (or, ecological production functions, EPFs) to describe the spatial distribution of ecosystem services. To generate EPFs for Yaquina estuary, Oregon, USA, we compared bird use patterns among intertidal habitats. Visual censuses were used to quantify abundance of bird groups and general species richness in: Zostera marina (eelgrass), Upogebia (mud shrimp)/mudflat, Neotrypaea (ghost shrimp)/sandflat, Zostera japonica (Japanese eelgrass), and low marsh estuarine habitats. Also assessed were (1) spatial variation within a habitat along the estuary gradient and, (2) temporal variation based on bi-monthly samples over a year at five tidal ranges. Z. marina was an important estuarine habitat based on nearly all metrics of bird use, except for shorebird densities. This suggests that reductions in native eelgrass habitat may reduce the abundance and diversity of birds in Yaquina estuary. Our results suggest that a habitat based assessment approach is generally feasible for developing relative EPFs related to the presence of birds within estuarine systems.     

Identifying factors that influence bird richness and abundance on farms

Capsule: Farmers can influence species richness and abundance of typical farmland birds positively, even on rather small farms (20–50?ha) within intensively farmed areas.

Aims: To assess the impact of farm settings, farm characteristics and heterogeneity of habitats on bird species richness and abundance, and to indicate which actions and measures farmers can take to promote farmland birds at a farm level.

Methods: Farmland bird species richness and abundance were modelled as a function of farm settings, farm characteristics and semi-natural habitats on 133 farms. The data were analysed at the farm scale, as this is the ‘operating range’ of a farmer, but also at the territory scale, which represents the range birds (mainly passerines) use during the breeding season. Additionally, effects of the farm variables on species abundance/occurrence were investigated for nine widespread species.

Results: Farmland bird species abundance (but not richness) was elevated on organic compared to non-organic farms. Farmland bird species richness and abundance increased with decreasing mean field size. Crop diversity had positive effects on five species at the territory scale. Several semi-natural habitats, especially hedgerows, were associated with higher bird species richness and abundance at both farm and territory scales. Settlement revealed rather negative effects at the farm scale, but several positive relations at the territory scale.

Conclusion: Birds, especially passerines, are restricted to a small area during the breeding season, and so even small farms can contribute to their protection by growing diverse crops, reducing field size and managing a diversity of semi-natural, uncropped habitats. These measures should ideally be accessible within the relatively small scale of a bird territory.     

A green design of city squares increases abundance and diversity of birds

Cities are designed for humans but are also highly dynamic ecosystems that provide habitats for wild animals. These habitats depend on a city's green infrastructure which is increasingly threatened by urban densification. A commonly studied model taxon for wild animals in cities are birds, and the importance of large green spaces for the diversity of birds in cities has been shown. However, how small-scale green spaces affect bird communities, which local characteristics are important, and whether there are seasonal differences remains unclear. We asked how and to what extent the characteristics of city squares in Munich affect the diversity and abundance of birds and if there are differences between bird communities in spring, autumn, and winter. We monitored birds on 103 city squares in Munich using a search-route method. Sampled squares spanned a spatial gradient from the center to the periphery of the city and differed in sealed surface proportion and vegetation structures, such as trees, shrubs, and lawns. The diversity and abundance of birds increased with a higher proportion of green characteristics on the square. Especially the proportion of grass cover and the density of trees had strong positive effects. Old trees had additional effects on birds beyond the effects of trees in general, while the mean number of people on a square negatively influenced bird abundance and diversity. Despite seasonal changes in bird composition, square characteristics showed consistent effects on bird abundance and diversity over seasons. These results underline that the green characteristics of city squares, and therefore of small-scale green spaces, affect their suitability as habitat for wildlife in cities. Integrating this knowledge into city planning can help to maintain or even increase urban biodiversity in the future.     

Evidence of endozoochory in upland geese Chloephaga picta and white‐bellied seedsnipes Attagis malouinus in sub‐Antarctic Chile

Birds are known to act as potential vectors for the exogenous dispersal of bryophyte diaspores. Given the totipotency of vegetative tissue of many bryophytes, birds could also contribute to endozoochorous bryophyte dispersal. Research has shown that fecal samples of the upland goose (Chloephaga picta) and white‐bellied seedsnipe (Attagis malouinus) contain bryophyte fragments. Although few fragments from bird feces have been known to regenerate, the evidence for the viability of diaspores following passage through the bird intestinal tract remains ambiguous. We evaluated the role of endozoochory in these same herbivorous and sympatric bird species in sub‐Antarctic Chile. We hypothesized that fragments of bryophyte gametophytes retrieved from their feces are viable and capable of regenerating new plant tissue. Eleven feces disk samples containing undetermined moss fragments from C. picta (N = 6) and A. malouinus (N = 5) and six moss fragment samples from wild‐collected mosses (Conostomum tetragonum, Syntrichia robusta, and Polytrichum strictum) were grown ex situ in peat soil and in vitro using a agar Gamborg medium. After 91 days, 20% of fragments from A. malouinus feces, 50% of fragments from C. picta feces, and 67% of propagules from wild mosses produced new growth. The fact that moss diaspores remained viable and can regenerate under experimental conditions following the passage through the intestinal tracts of these robust fliers and altitudinal and latitudinal migrants suggests that sub‐Antarctic birds might play a role in bryophyte dispersal. This relationship may have important implications in the way bryophytes disperse and colonize habitats facing climate change.     

Chicken- and duck-associated Bacteroides–Prevotella genetic markers for detecting fecal contamination in environmental water

Bacteroides–Prevotella group is one of the most promising targets for detecting fecal contamination in water environments, principally due to its host-specific distributions and high concentrations in feces of warm-blooded animals. We developed real-time PCR assays for quantifying chicken/duck-, chicken-, and duck-associated Bacteroides–Prevotella 16S rRNA genetic markers (Chicken/Duck-Bac, Chicken-Bac, and Duck-Bac). A reference collection of DNA extracts from 143 individual fecal samples and wastewater treatment plant influent was tested by the newly established markers. The quantification limits of Chicken/Duck-Bac, Chicken-Bac, and Duck-Bac markers in environmental water were 54, 57, and 12 copies/reaction, respectively. It was possible to detect possible fecal contaminations from wild ducks in environmental water with the constructed genetic marker assays, even though the density of total coliforms in the identical water samples was below the detection limit. Chicken/Duck-Bac marker was amplified from feces of wild duck and chicken with the positive ratio of 96 and 61 %, respectively, and no cross-reaction was observed for the other animal feces. Chicken-Bac marker was detected from 70 % of chicken feces, while detected from 39 % of cow feces, 8.3 % of pig feces, and 12 % of swan feces. Duck-Bac marker was detected from 85 % of wild duck feces and cross-reacted with 31 % of cow feces. These levels of detection specificity are common in avian-associated genetic markers previously proposed, which implies that there is a practical limitation in the independent application of avian-associated Bacteroides–Prevotella 16S rRNA genetic markers and a combination with other fecal contamination markers is preferable for detecting fecal contamination in water environments.     

Discrimination Efficacy of Fecal Pollution Detection in Different Aquatic Habitats of a High-Altitude Tropical Country, Using Presumptive Coliforms, Escherichia coli, and Clostridium perfringens Spores

The performance of rapid and practicable techniques that presumptively identify total coliforms (TC), fecal coliforms (FC), Escherichia coli, and Clostridium perfringens spores (CP) by testing them on a pollution gradient in differing aquatic habitats in a high-altitude tropical country was evaluated during a 12-month period. Site selection was based on high and low anthropogenic influence criteria of paired sites including six spring, six stream, and four lakeshore sites spread over central and eastern parts of Uganda. Unlike the chemophysical water quality, which was water source type dependent (i.e., spring, lake, or stream), fecal indicators were associated with the anthropogenic influence status of the respective sites. A total of 79% of the total variability, including all the determined four bacteriological and five chemophysical parameters, could be assigned to either a pollution, a habitat, or a metabolic activity component by principal-component analysis. Bacteriological indicators revealed significant correlations to the pollution component, reflecting that anthropogenic contamination gradients were followed. Discrimination sensitivity analysis revealed high ability of E. coli to differentiate between high and low levels of anthropogenic influence. CP also showed a reasonable level of discrimination, although FC and TC were found to have worse discrimination efficacy. Nonpoint influence by soil erosion could not be detected during the study period by correlation analysis, although a theoretical contamination potential existed, as investigated soils in the immediate surroundings often contained relevant concentrations of fecal indicators. The outcome of this study indicates that rapid techniques for presumptive E. coli and CP determination may be reliable for fecal pollution monitoring in high-altitude tropical developing countries such as those of Eastern Africa.     

Livestock grazing constrains bird abundance and species richness: A global meta-analysis

Balancing food production and biodiversity conservation is a global challenge today. Livestock grazing is one of the main activities triggering habitat degradation and land-use change around the world. Its effects on biodiversity have been widely explored, with birds being the most studied vertebrates. However, its impact seems to be contradictory given the disparity of the results. To understand the influence of livestock grazing on birds, we conducted a meta-analysis exploring the effects of several grazing characteristics on bird abundance and species richness. Our results showed that livestock grazing has a significant negative effect on bird abundance (mean effect size -0.422 ± 0.140), and species richness (mean effect size -0.391 ± 0.141). Livestock grazing affected negatively the bird abundance in riparian habitats in contrast to the other habitat types. Species richness was negatively affected by grazing in woody habitats and Afrotropical and Neotropical regions. Grazing by cattle was more detrimental for both bird richness and abundance than sheep grazing or a mixture of domestic livestock. Moreover, intermediate grazing intensity seems appropriate to maintain bird abundance and richness, as high grazing intensity dropped both bird abundance and species richness substantially, and low grazing intensity reduced bird species richness. This pattern supposes a non-linear effect of grazing intensity on birds. Therefore, the management of grazing intensity and type of livestock could help to reduce the negative effect on bird abundance and richness, as moderate grazing intensities and mix of livestock types appear to have a minor or null impact on bird abundance and richness. Future studies should explore in-depth the effect of moderate grazing intensities on bird diversity and composition to provide better management recommendations to enhance avian conservation in rangelands.     

Ecosystem recharge by volcanic dust drives broad‐scale variation in bird abundance

Across the globe, deserts and volcanic eruptions produce large volumes of atmospheric dust, and the amount of dust is predicted to increase with global warming. The effects of long‐distance airborne dust inputs on ecosystem productivity are potentially far‐reaching but have primarily been measured in soil and plants. Airborne dust could also drive distribution and abundance at higher trophic levels, but opportunities to explore these relationships are rare. Here we use Iceland's steep dust deposition gradients to assess the influence of dust on the distribution and abundance of internationally important ground‐nesting bird populations. Surveys of the abundance of breeding birds at 729 locations throughout lowland Iceland were used to explore the influence of dust deposition on bird abundance in agricultural, dry, and wet habitats. Dust deposition had a strong positive effect on bird abundance across Iceland in dry and wet habitats, but not in agricultural land where nutrient levels are managed. The abundance of breeding waders, the dominant group of terrestrial birds in Iceland, tripled on average between the lowest and highest dust deposition classes in both wet and dry habitats. The deposition and redistribution of volcanic materials can have powerful impacts in terrestrial ecosystems and can be a major driver of the abundance of higher trophic‐level organisms at broad spatial scales. The impacts of volcanic ash deposition during eruptions and subsequent redistribution of unstable volcanic materials are strong enough to override effects of underlying variation in organic matter and clay content on ecosystem fertility. Global rates of atmospheric dust deposition are likely to increase with increasing desertification and glacier retreat, and this study demonstrates that the effects on ecosystems are likely to be far‐reaching, both in terms of spatial scales and ecosystem components.     

Biodiversity in the floodplain of Saône: a global approach

Biodiversity of European floodplains is seriously threatened mainly due to (1) modifications of river courses such as channelisation or embankments, and (2) changes in traditional agricultural practices (i.e. usually pastures), into intensive production using drainage and fertilisation. A upstream-downstream survey of the Saône floodplain (France) has been done to identify the contribution of habitats to the floodplain biodiversity. Selected taxa were aquatic and terrestrial vegetation, Odonata, Coleoptera, Amphibians, and birds. The taxa were sampled in different habitat types that were: forests, grasslands and aquatic habitats. Tributary confluences with the river and cut-off channels contributed greatly to the floodplain diversity according to their invertebrates and aquatic vegetation communities. The abundance of rare species (benefitting of a national or regional protection status) was the highest in hygrophilous grasslands. Moreover, we demonstrated that diversity of breeding bird communities was correlated with the size of these habitats. We demonstrated also that alluvial forests contributed to maintain some particular species as Middle-spotted Woodpecker (Dendrocopus medius), while new plantations were colonized by openland bird communities sensible to the edge effect. Grassland fragmentation for agriculture appeared to be a major cause in biodiversity loss. Any alteration of the floodplain dynamics must be avoided to preserve the present diversity of riverine wetlands.