Large animals including waterbirds are traditionally considered passengers in wetland ecosystems and used as indicator, flagship or umbrella species in wetland conservation, but whether they are ...drivers of wetland ecosystem patterns and dynamics is poorly understood. Combining a field experiment in a tidal flat in the Yangtze estuary and a global meta-analysis, we tested the hypothesis that waterbirds exert top-down control on wetland macrofauna. Waterbird exclusion more than doubled the abundance of grazing crabs in our field experiment but did not affect other macrofauna. Conversely, excluding grazing crabs to simulate above-current levels of waterbird predation increased macrofauna abundance and biomass and decreased their diversity, ostensibly by allowing the establishment of habitat-engineering plants otherwise eliminated by crab grazing. Meta-analysis of 135 tests revealed that waterbirds had negative, positive, or neutral effects on macrofauna, with an overall significantly negative effect. This finding was evident across different seasons, wetland types and macrofauna classes and was largely based on tests from coastal rather than inland wetlands in Europe and Americas and none in Asia and Australasia. Our results suggest that the roles of waterbirds in wetlands are more diverse and profound than currently recognized and that their driver roles in shaping wetland ecosystems warrant incorporation into conservation decisions.
Plastic pollution constitutes an environmental problem in the Canary Islands nowadays. Nevertheless, studies evaluating the impact of plastics on its avifauna are still scarce. Gastrointestinal ...tracts of 88 birds belonging to 14 species were studied for the presence of plastics. Moreover, their livers were analyzed for the determination of bromodiphenyl ethers (BDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). Among Cory's shearwaters (n = 45), the frequency of occurrence of plastic ingestion was considerably high (88.89 %). This species had the highest mean value of items (7.22 ± 5.66) and most of them were compatible with lines derived from fishing gear. PCBs and PAHs were detected in all of the samples and OCPs in the great majority of them (98.86 %). Our results highlight the problems that plastic debris (mainly for seabirds) and organic pollutants pose to these species.
•Plastic ingestion and hepatic chemical pollutants were studied in 88 birds of 14 species.•High frequency of plastic ingestion in Calonectris borealis and Oceanodroma castro and lower in Larus michahellis.•High proportion of plastics derived from fishing gear.•Detection of PCBs and PAHs in all birds.
Dabbling ducks (Anatinae) are omnivorous birds that are widespread, numerous, highly mobile and often migratory, and therefore have great potential for (long distance) dispersal of other organisms, ...including plants. However, their ability to act as plant dispersal vectors has received little attention compared to frugivores and is often assumed to be relevant only for wetland species. To evaluate the potential for plant dispersal by dabbling ducks, we collated and analysed existing data. We identified all plant species whose seeds have been recorded in the diets of the seven dabbling duck (Anas) species in the Western Palaearctic, as reported from gut content analyses. We then analysed the habitats and traits of these plant species to identify general patterns, and related these to data on gut passage survival and duck movements. A large number of plant species (> 445 species of 189 genera and 57 families) have been recorded in the diet of dabbling ducks. These plant species represent a very wide range of habitats, including almost the full range of site fertility, moisture and light conditions, excluding only very dry and deeply shaded habitats. The ducks prefer seeds of intermediate sizes (1–10 mm³), which have good chances to survive gut passage, but also ingest smaller and larger seeds. Ingested seeds represent a wide range of dispersal syndromes, including fleshy fruits. Many species (62%) were not previously considered animal‐dispersed in plant data bases, and 66% were not identified as bird‐dispersed. Rarefaction analyses suggest that our analysis still greatly underestimates the total number of plant species ingested. Synthesis. Dabbling ducks do not exclusively ingest seeds of wetland plants, which make up only 40% of the ingested species. Rather, they feed opportunistically on a wide cross‐section of plant species available across the landscapes they inhabit. Given the millions of ducks, the hundreds to thousands of seeds ingested per individual on a daily basis, and known gut passage survival rates, this results in vast numbers of seeds dispersed by ducks per day. Internal seed dispersal by dabbling ducks appears to be a major dispersal pathway for a far broader spectrum of plant species than previously considered.
Summary
We present new models and methods for the posterior drift problem where the regression function in the target domain is modelled as a linear adjustment, on an appropriate scale, of that in ...the source domain, and study the theoretical properties of our proposed estimators in the binary classification problem. The core idea of our model inherits the simplicity and the usefulness of generalized linear models and accelerated failure time models from the classical statistics literature. Our approach is shown to be flexible and applicable in a variety of statistical settings, and can be adopted for transfer learning problems in various domains including epidemiology, genetics and biomedicine. As concrete applications, we illustrate the power of our approach (i) through mortality prediction for British Asians by borrowing strength from similar data from the larger pool of British Caucasians, using the UK Biobank data, and (ii) in overcoming a spurious correlation present in the source domain of the Waterbirds dataset.
•A process-based dynamic model has been developed to understand the impact of guanotrophy on the dynamics of a freshwater lake considering phosphorous as model currency.•Phosphorus content in ...zooplankton found as the most sensitive state variable for changes in all parameters. Parameters affecting the sediment-water exchange were found as the highly sensitive to the overall system.•Nutrient budget analysis shows that waterbirds are main nutrient importer to the ecosystem.•Internal cycling via sediment-water exchange of phosphorus appears to be the most important process to regulate the nutrient dynamics in this shallow lake. The lake is found to be a phosphorous sink.
Many freshwater ecosystems throughout the world support a high number of waterbirds. Nutrient from droppings of these waterbirds may serve as an important source of nutrients to those systems. Previous works suggest that excess nutrients from waterbirds may lead to eutrophication. The excess nutrients also may induce nuisance growth of aquatic weeds in shallow lakes. However, the aquatic weeds serve as an important food for some avian species. The main objective of this work is to study how the waterbirds affect the dynamics of the aquatic ecosystem through a process-based modelling approach.
To understand this, a lake with negligible anthropogenic nutrient influx and the high winter-avian congregation is taken as study site. A process-based dynamic ecological model with six state variables has been developed. Phosphorus (P) is taken as model currency since it is the limiting nutrient in most shallow and present in high concentration in the dropping of waterbirds. Before the model calibration, sensitivity analysis is performed with the data collected during the first year of study. Model is validated with the data collected during the second year of study.
As per the model, P from the waterbird guano comprises 98.32% of P input to the lake. Parameters affecting the water-sediment exchange of P are most sensitive. P content in zooplankton is the most sensitive state variable. Nutrient budget analysis reveals that internal cycling of the nutrient is the main pathway to sustain productivity in the system. So far, no process-based modelling has been done on the impact of dropping of waterbird on nutrient dynamics of the aquatic system. This kind of model will be helpful to handle problems like eutrophication and macrophyte overgrowth due to eutrophication.
Waterbirds are vital to coastal wetland ecosystem, and play significant roles in global biodiversity maintenance, cultural and educational services, etc. Waterbirds are particularly vulnerable to ...environmental change, particularly land-cover change, which has severely degraded their ecological niches. Accordingly, this study developed a waterbird-habitat preference index to quantify waterbird dependence on Xiamen Bay's habitats and a subsidiary waterbird-specific habitat suitability index to predict potential effects of future land-cover change on waterbirds. Results showed that the waterbird-habitat preference index ranged from −9.8 to 18.71, indicating that habitat selection varied greatly among different waterbird species, where tidal flats were the most popular waterbird habitat. Additionally, most waterbird species showed a preference for more than one habitat, which could be indicative of their diverse ecological demands. Effects on waterbirds varied greatly among the three different land-cover scenarios, where positive benefits were predicted under the ecological protection scenario (EPS), while the greatest negative effects were observed under the development and utilization scenario (DUS). Effects also varied among different waterbirds species. Those under the current trend scenario (CTS) (e.g., Tringa brevipes and Calidris ruficollis) could be at risk for species abundance loss (i.e., losers) while others (i.e., Egretta garzetta and Saundersilarus saundersi) could benefit from increased abundance (i.e., winners). Generally, migratory and traveling birds were much more vulnerable than resident birds. Spatially, conservation priority should be given to the Dadeng Waters and those waters adjacent to it (i.e., Tongan Bay and Anhai Bay) because of the highest waterbird loss risk in these areas under a conflict between an urgent need to protect waterbird biodiversity and intense present and future land-cover development. The intent of this study is to provide a useful tool to explore land-cover effects on waterbirds in similar coastal regions, which can provide important information on protection and restoration strategies.
•A waterbird-habitat preference index was developed to quantify waterbird dependence on a specific habitat.•Potential effects of future land-cover change on waterbirds was predicted.•Effects on waterbirds varied greatly among different land-cover scenarios.•Migratory and traveling birds were at the greater risk of regional loss than resident birds.
•Plastic waste contamination is a major emerging problem in aquatic ecosystems.•Gulls egest pellets carrying plastics into wetlands after feeding at landfills.•Plastic biovectoring was quantified ...using GPS and FTIR techniques.•Gulls transported 400 kg of plastic per year into a closed-basin lake.•Polyethylene was the most common plastic type.
Gulls ingest plastic and other litter while foraging in open landfills, because organic matter is mixed with other debris. Therefore, gulls are potential biovectors of plastic pollution into natural habitats, especially when they concentrate in wetlands for roosting.
We quantified, for the first time, the flow of plastic and other anthropogenic debris from open landfills to a natural lake via the movement of gulls. We focused on Fuente de Piedra, an inland closed-basin lake in Spain that is internationally important for biodiversity.
In 2022, we sampled gull pellets regurgitated in the lake by lesser black-backed gulls Larus fuscus that feed on landfills, as well as their faeces, then characterized and quantified debris particles of ≥0.5 mm. By combining GPS and census data from 2010 to 2022, together with plastic quantification based on FTIR-ATR analysis, we estimated the average annual deposition of plastic and other debris by the wintering gull population into the lake.
86 % of pellets contained plastics, and 94 % contained other debris such as glass and textiles. Polyethylene (54 %), polypropylene (11.5 %) and polystyrene (11.5 %) were the main plastic polymers. An estimated annual mean of 400 kg of plastics were moved by gulls into the lake. Only 1 % of plastic mass was imported in faeces.
Incorporating the biovectoring role of birds can provide a more holistic view of the plastic cycle and waste management. Biovectoring is predictable in sites worldwide where gulls and other waterbirds feed in landfills and roost in wetlands. We discuss bird deterrence and other ways of mitigating debris leakage into aquatic ecosystems.
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