Natural Wetlands Research Articles

Driving Force Analysis of Natural Wetland in Northeast Plain Based on SSA-XGBoost Model.

Globally, natural wetlands have suffered severe ecological degradation (vegetation, soil, and biotic community) due to multiple factors. Understanding the spatiotemporal dynamics and driving forces of natural wetlands is the key to natural wetlands' protection and regional restoration. In this study, we first investigated the spatiotemporal evolutionary trends and shifting characteristics of natural wetlands in the Northeast Plain of China from 1990 to 2020. A dataset of driving-force evaluation indicators was constructed with nine indirect (elevation, temperature, road network, etc.) and four direct influencing factors (dryland, paddy field, woodland, grassland). Finally, we built the driving force analysis model of natural wetlands changes to quantitatively refine the contribution of different driving factors for natural wetlands' dynamic change by introducing the sparrow search algorithm (SSA) and extreme gradient boosting algorithm (XGBoost). The results showed that the total area of natural wetlands in the Northeast Plain of China increased by 32% from 1990 to 2020, mainly showing a first decline and then an increasing trend. Combined with the results of transfer intensity, we found that the substantial turn-out phenomenon of natural wetlands occurred in 2000-2005 and was mainly concentrated in the central and eastern parts of the Northeast Plain, while the substantial turn-in phenomenon of 2005-2010 was mainly located in the northeast of the study area. Compared with a traditional regression model, the SSA-XGBoost model not only weakened the multicollinearity of each driver but also significantly improved the generalization ability and interpretability of the model. The coefficient of determination (R2) of the SSA-XGBoost model exceeded 0.6 in both the natural wetland decline and rise cycles, which could effectively quantify the contribution of each driving factor. From the results of the model calculations, agricultural activities consisting of dryland and paddy fields during the entire cycle of natural wetland change were the main driving factors, with relative contributions of 18.59% and 15.40%, respectively. Both meteorological (temperature, precipitation) and topographic factors (elevation, slope) had a driving role in the spatiotemporal variation of natural wetlands. The gross domestic product (GDP) had the lowest contribution to natural wetlands' variation. This study provides a new method of quantitative analysis based on machine learning theory for determining the causes of natural wetland changes; it can be applied to large spatial scale areas, which is essential for a rapid monitoring of natural wetlands' resources and an accurate decision-making on the ecological environment's security.

A review of climate change mitigation and agriculture sustainability through soil carbon sequestration

As a result of human activities such as burning fossil fuels, organic materials, and engaging in unsustainable land practices, atmospheric carbon dioxide (CO2) levels have been steadily rising, heightening worldwide concerns about climate change. It is expected concentrations to grow and changes in CO2 sequestration in agricultural soils as a result of the industrial revolution's acceleration of CO2 emissions. These emissions have been intensified by changes in land use, such as cutting down trees, burning biomass, altering farming operations, draining natural wetlands, and using the wrong methods for managing soil. The present study utilized the systematic literature review method to investigate soil carbon sequestration options as a possible means of reducing the impact of climate change and improving agriculture sustainability. As a result of soil degradation and poor management, soil organic carbon (SOC) levels have decreased, which in turn has increased atmospheric CO2 levels. But cutting-edge land application and modern agricultural management methods have the ability to reduce CO2 emissions. Several methods exist for replenishing depleted SOC, such as repurposing marginal lands for restoration purposes, advocating for reduced or zero-tillage methods in conjunction with cover as well as residue crops, and introducing nutrient cycling through composting, manure usage, and other environmentally friendly approaches to managing soil and water. One holistic approach to fighting climate change is long-term soil carbon sequestration. Soil carbon sequestration offers a comprehensive and efficient strategy for reducing the impact of climate change by recharging depleted soils, increasing biomass production, cleaning surface and underground water sources, and compensating for CO2 emissions through fossil fuels. Soil carbon sequestration presents an exciting opportunity for management of the problems caused by contemporary changes in the environment, and the adoption of these novel approaches is essential for meeting these issues.

Time-lag effects of flood stimulation on methane emissions in the Dongting Lake floodplain, China

Natural wetlands are the primary sources of CH4 emissions in the natural environment. However, the understanding of CH4 fluxes in floodplain wetlands remains limited. This study employed eddy covariance methods to observe CH4 fluxes over a three-year period in a subtropical wetland floodplain, specifically the Miscanthus sacchariflorus (M. sacchariflorus) ecosystem in Dongting Lake wetland. Our analysis focused on exploring the impact of flooding frequency on CH4 emissions, flood stimulation effect, time-lag effects, and the environmental factors influencing CH4 fluxes. The M. sacchariflorus ecosystem exhibited an annual CH4 emission rate of 14.54 g CH4C m−2 y−1. During the flood period, the average daily CH4 emissions reached 0.155 g CH4C m−2 d−1, contrasting with the pre-flood period's average of 0.014 g CH4C m−2 d−1. Moreover, the time-lag effect of flooding on CH4 emissions was found to be 10 days, representing the period between inundation and a substantial increase in CH4 emissions. Comparatively, in 2021, following three fluctuations in floodwaters, the average CH4 emission intensity during the flood period decreased by 46.2% and 48.9% when compared to the years 2019 and 2020 which both following one fluctuation, respectively. CH4 emissions during flooding are predominantly influenced by water depth (WD), wherein shallow WD corresponds to higher CH4 emissions. This correlation can be attributed to factors such as vegetation type, water-column pressure, and soil oxygen content. Therefore, increasing frequency of inundation and a higher WD hold promise as effective measures for mitigating CH4 emissions in floodplain wetlands.

Using water sources extent during inundation as a reliable predictor for vegetation zonation in a natural wetland floodplain

Distinctive zones of inundation water during floods were shown to originate from different sources in some major floodplains around the world. Recent research showed that the zonation of water in rivers and floodplains is related to vegetation patterns. In spite of this, water source zones were not used for vegetation modeling due to difficulties in their delineation. In this study, we used simulation results of a fully-coupled groundwater-surface water integrated hydrological model (IHM) HydroGeoSphere and the Hydraulic Mixing-Cell method to provide standard hydrological predictors (e.g. water depth, inundation length, groundwater depth, exchange flux) and the extent of inundation zones having a certain water source (discharged groundwater, river, rainfall, and snowmelt). These variables were used to train a vegetation model for the lower Biebrza floodplain (about 290 km2) using vegetation maps from 1960, 1980, and 2000. We used a one-at-a-time (OAT) approach, where each map was validated based on a model trained on the remaining two maps to obtain realistic error estimates. We also used a fractional approach in which a fraction of each map was used for training and validation. The single model from the fractional approach was used to assess the importance of predictors and to predict vegetation for the 20th century and for the 21st century using IHM simulation forced by the Twentieth Century Reanalysis data and EURO-CORDEX RCP 2.6, 4.5, and 8.5 model ensembles. The model which used both water sources extent and standard predictors performed the best overall and was sensitive to the future trends. The extent of river water within the inundation area was by far the most important vegetation predictor. The models that neither used the water sources extent predictors nor the exchange flux were not able to predict the trends of areas covered by certain vegetation types under future climate. The advantage of the water sources extent predictors was their ability to represent the spatial effect of local hydrological phenomena. This was not possible with the standard predictors, because they show only the source of the phenomena (e.g. groundwater discharge zone), but do not indicate the actual area affected by its physical and chemical properties, which is more relevant for vegetation development. Our results highlight the relevance of using water extent predictors due to their ability to explain spatiotemporal ecological processes, such as vegetation development. We suggest to use water extent predictors in modelling for developing more accurate decision support for wetland floodplains.

Nitrogen loss through anaerobic ammonium oxidation coupled with ferric iron reduction in the Yellow River Wetland, Sanmenxia, China

Anaerobic ammonium oxidation coupled with iron(III) reduction (Feammox) is a recently discovered pathway of nitrogen removal. However, little is known about the pathways of N transformation via Feammox in the Yellow River wetland. In this study, the difference between Feammox in a natural wetland (site YJW) and a crop rotation wetland (site TEH) was researched using isotope tracing and metagenome techniques. The results revealed that Feammox occurred in TEH but not in YJW. The Feammox rates in the TEH samples were 0.02–0.13 mg N kg−1 d−1 in different depth intervals (0–5 cm, 5–10 cm, 10–20 cm, and 20–30 cm), and the maximum value for TEH occurred in the 5–10 cm depth interval. Iron reducing bacteria play an essential role in Feammox. Rotational tillage reduced the microbial diversity of the iron-reducing bacteria, but it increased the abundance of iron-reducing bacteria at the genus level, and the dominate iron-reducing bacteria responsible for the Feammox process were Anaeromyxobacter and Geobacter. The Feammox rate was less than the denitrification rate (0.55–1.09 mg N kg−1 d−1), an estimated nitrogen loss of 1.1–7.1 t N km−2 a−1 was associated with the Feammox in the wetland. However, the correlation between the functional genes of the iron-reducing bacteria and the rate remains unclear.

Use of High-Resolution Land Cover Maps to Support the Maintenance of the NWI Geospatial Dataset: A Case Study in a Coastal New Orleans Region

The National Wetlands Inventory (NWI) is the most comprehensive wetland geospatial dataset in the United States. However, it can be time-consuming and costly to maintain. This study introduces automated algorithms and methods to support NWI maintenance. Through a wall-to-wall comparison between NWI and Coastal Change Analysis Program (C-CAP) datasets, a pixel-level difference product was generated at 1 m resolution. Building upon this, supplementary attributes describing wetland changes were incorporated into each NWI polygon. Additionally, new water polygons were extracted from C-CAP data, and regional statistics regarding wetland changes were computed for HUC12 watersheds. The 1 m difference product can indicate specific wetland change locations, such as wetland loss to impervious surfaces, the gain of open water bodies from uplands, and the conversion of drier vegetated wetlands to open water. The supplementary attributes can indicate the amount and percentage of wetland loss or water regime change for NWI polygons. Extracted new water polygons can serve as preliminary materials for generating NWI standard-compliant products, expediating NWI maintenance processes while reducing costs. Regional statistics of wetland change can help target watersheds with the most significant changes for maintenance, thereby reducing work areas. The approaches we present hold significant value in supporting NWI maintenance.

Assessment of contaminants, health and survival of migratory shorebirds in natural versus artificial wetlands – The potential of wastewater treatment plants as alternative habitats

The rapid destruction of natural wetland habitats over past decades has been partially offset by an increase in artificial wetlands. However, these also include wastewater treatment plants, which may pose a pollution risk to the wildlife using them. We studied two long-distance Arctic-breeding migratory shorebird species, curlew sandpiper (Calidris ferruginea, n = 69) and red-necked stint (Calidris ruficollis, n = 103), while on their Australian non-breeding grounds using an artificial wetland at a wastewater treatment plant (WTP) and a natural coastal wetland. We compared pollutant exposure (elements and per- and poly-fluoroalkyl substances/PFASs), disease (avian influenza), physiological status (oxidative stress) of the birds at the two locations from 2011 to 2020, and population survival from 1978 to 2019. Our results indicated no significant differences in blood pellet pollutant concentrations between the habitats except mercury (WTP median: 224 ng/g, range: 19–873 ng/g; natural wetland: 160 ng/g, 22–998 ng/g) and PFASs (total PFASs WTP median: 85.1 ng/g, range: <0.01–836 ng/g; natural wetland: 8.02 ng/g, <0.01–85.3 ng/g) which were higher at the WTP, and selenium which was lower at the WTP (WTP median: 5000 ng/g, range: 1950–34,400 ng/g; natural wetland: 19,200 ng/g, 4130–65,200 ng/g). We also measured higher blood o,o′-dityrosine (an indicator of protein damage) at the WTP. No significant differences were found for adult survival, but survival of immature birds at the WTP appeared to be lower which could be due to higher dispersal to other wetlands. Interestingly, we found active avian influenza infections were higher in the natural habitat, while seropositivity was higher in the WTP, seemingly not directly related to pollutant exposure. Overall, we found limited differences in pollutant exposure, health and survival of the shorebirds in the two habitats. Our findings suggest that appropriately managed wastewater treatment wetlands could provide a suitable alternative habitat to these migratory species, which may aid in curbing the decline of shorebird populations from widespread habitat loss.

Major Role of Natural Wetland Loss in the Decline of Wetland Habitat Quality—Spatio-Temporal Monitoring and Predictive Analysis

Land use change significantly affects habitat quality, and the long time series exploration of dynamic variations in wetland habitat quality is of great significance to wetland conservation and management practices. Jingxin Wetland is located in the lower reaches of the Tumen River Basin, an important ecological function area in China. In recent years, under the influence of human activities and climate change, Jingxin Wetland has faced the threat of degradation and reclamation. This study investigated the dynamic evolution of habitat quality in Jingxin Wetland based on the CA-Markov model and the InVEST model at a long time scale and analyzed the drivers of habitat quality changes. Furthermore, habitat statuses under different policy orientations were explored using a multi-scenario development model. The results show that the total area of Jingxin Wetland exhibited a shrinking trend from 1964 to 2019, the wetland landscape was more fragmented, and the loss of natural wetland (marsh wetland) was serious. Consequently, wetland habitat quality has declined. According to scenario analysis, the study area should firmly follow the ecological conservation route in the future, through which the encroachment of human activities on wetlands can be effectively reduced and habitat conditions can be effectively improved. Both natural and economic development scenarios would result in the shrinkage of wetlands, which will extend the trend of declining habitat quality. It is noteworthy that the loss of wetland can be effectively reduced by implementing ecological conservation policies, which would reduce the degradation of wetland habitat quality. The results of this study can provide valuable references for wetland ecological conservation and ecological management practices.

Traits for transport: Alien wetland plants gain an advantage during endozoochorous seed dispersal by waterfowl

Abstract The expansion of alien plant species is of global concern, yet our understanding of their dispersal mechanisms is limited. Here we address the potential of alien plant seeds to disperse via ingestion, transport and egestion in waterfowl (endozoochory). Based on their general rapid expansions, we expected alien plant species to have several advantages for endozoochory compared to native plant species. We hypothesised that seeds of alien species would have higher passage rate, longer gut retention times, higher germinability after gut passage and shorter time‐to‐germination after egestion by waterfowl. In order to test our hypotheses, we compared the endozoochorous dispersal ability of six pairs of congeneric alien and native wetland plant species in a feeding experiment with mallards (Anas platyrhynchos). We focused on differences in seed survival, gut retention time, germinability and time‐to‐germination. In the analyses we corrected for seed shape and volume as these seed traits are known to have important effects. With gut passage, alien species had higher passage rates and germinated slower, whereas native species had shorter retention times and greater germinability. Controlling for seed traits did not alter these conclusions, but seed traits affected all aspects of the endozoochory process. This suggests that alien species may have particular traits correlated with a higher endozoochory potential. Among control seeds, alien seeds germinated faster and their germinability was higher than natives. Seed traits explained differences in germinability and time‐to‐germination in control seeds. Seeds of alien plant species have traits that correlate with successful endozoochory. This may provide alien species with a competitive advantage over native plant species by ensuring higher endozoochory rates in new environments, potentially enabling their rapid expansions. Our study underlines the important role of seed traits in the endozoochory potential of alien and native plant species, notably through their influence on retention time and germination.

Aboveground Biomass Dynamics of a Coastal Wetland Ecosystem Driven by Land Use/Land Cover Transformation

Accurately estimating aboveground biomass (AGB) is essential for assessing the ecological functions of coastal wetlands, and AGB of coastal wetlands is affected by Land use/land cover (LULC) types of conversion. To address this issue, in the current study, we used the Boreal Ecosystem Productivity Simulator (BEPS) model to simulate the AGB of the Yellow River Delta during 2000–2015. Based on the LULC types transform, we analyzed the spatiotemporal dynamics of the AGB simulation results and their relationship with the human-nature driving process. At the same time, combined with the actual situation of LULC transformation in the Yellow River Delta, a new driving process (Replace) is introduced. The results show that from 2000 to 2015, 755 km2 of natural wetlands in the Yellow River Delta were converted into constructed wetlands, and AGB increased by 386,121 Mg. Both single and multiple driving processes contributed to the decrease in AGB, with 72.6% of the increase in AGB associated with single artificial (such as Restore) or natural (such as Accretion) driving processes and 27.4% of the increase in AGB associated with multiple driving processes. Naturally driven processes bring much more AGB gain than loss, and human-driven processes bring the largest AGB gain. LULC conversion brought on by anthropogenic and natural driving processes has a large impact on AGB in coastal wetlands, and exploring this impact has a significant role in planning coastal wetland land use and protecting blue carbon ecosystems.

Composition and assembly mechanisms of prokaryotic communities in wetlands, and their relationships with different vegetation and reclamation methods

Coastal wetlands are undergoing substantial transformations globally as a result of increased human activities. However, compared to other ecosystems, diversity and functional characteristics of microbial communities in reclaimed coastal wetlands are not well studied compared to other ecosystems. This is important because it is known that microorganisms can play a crucial role in biogeochemical cycling within coastal wetland ecosystems. Hence, this study utilized the high-throughput sequencing technique to investigate the structure and assembly processes of microbial communities in reclaimed coastal wetlands. The results revealed a substantial change in soil properties following coastal wetland reclamation. Remarkably, the reclaimed soil exhibited significantly lower pH, soil organic carbon (SOC), and total salinity (TS) values (p < 0.05). The dominant phyla included Proteobacteria, Chloroflexi, Bacteroidetes, Acidobacteria, and Planctomycetes among study sites. However, the relative abundance of Proteobacteria increased from un-reclaimed coastal wetlands to reclaimed ones. The Proteobacteria, Chloroflexi, and Acidobacteria showed higher relative abundance in vegetated soil compared to bare soil, while Bacteroidetes and Planctomycetes exhibited the opposite trend. Notably, vegetation types exerted the strongest influence on microbial diversity, surpassing the effects of soil types and depth (F = 34.49, p < 0.001; F = 25.49, p < 0.001; F = 3.173, p < 0.078, respectively). Stochastic assembly processes dominated in un-reclaimed soil, whereas deterministic processes governed the assembly in artificial sea embankment wetlands (SEW). The presence of Spartina alterniflora in all soil types (except SEW soils) indicated stochastic assembly, while Phragmites australis in reclaimed soils pointed toward deterministic microbial assembly. Furthermore, environmental factors such as pH, soil water content (SWC), SOC, total carbon (TC), total nitrogen (TN), total phosphorus (TP), NH4+-N, vegetation types, soil depth, and geographic distance exhibited significant effects on microbial beta diversity indices. Co-occurrence network analysis revealed a stronger association between taxa in SEW compared to land reclaimed from wetlands (LRW) and natural coastal wetlands (NCW). The bottom soil layer exhibited more complex network interactions than the topsoil layer. Besides soil parameters, reclamation and varieties of vegetation were also substantial factors influencing the composition, diversity, and assembly processes of microbial communities in coastal wetlands.

Coastal wetland degradation and ecosystem service value change in the Yellow River Delta, China

The characteristics of changes in wetlands in different coastal areas vary, so it is necessary to select representative experimental areas to research wetland degradation, ecosystem service values (ESVs) and differences in changes among various wetland types in different ecological service function fields. The goal of this study is to better realize the spatiotemporal characteristics of wetland degradation and ESV in order to balance economic advancement and wetland ecological protection. The evolution of the wetland ESVs was analyzed by using the ESV equivalent correction technique and ecological contribution degree. The random forest (RF) classification model was utilized to extract wetland information in the Yellow River Delta (YRD) in four years (1990, 2000, 2010, and 2020). Thoroughly exploring the mechanism of impact and proposing reasonable suggestions based on a close combination of wetland changes and ecological services are conducive to the healthy development of global wetlands. The results demonstrated that the total area of wetlands expanded from 1459.5 km2 in 1990–1975.5 km2 in 2020, an increase of 28.5 %, with artificial wetlands increasing from 151.4 km2 to 1059.1 km2 and natural wetlands decreasing from 1308.1 km2 to 916.5 km2. The wetland ESV increased from 18.4 billion USD in 1990–28.6 billion USD in 2020. The transformation between types of natural wetlands tended to increase the ESV, while the transformation from natural wetlands to constructed wetlands reduced the ESV. The tidal flats and herbaceous wetlands have great value in terms of not only hydrological regulation but also gene diversity and climate regulation. The significant changes in various wetlands cause changes in different ecological service functions and promote changes in the ESV. Wetland protection, restoration, reconstruction, and rational utilization must be incorporated into urban land planning, and wetland parks and wetland protection zones should be established according to local conditions. This above research can provide typical examples and references for global wetland protection and sustainable development.

Abating eutrophication on urban lakes: a case study of Kabaka's Lake, Uganda

Abstract Eutrophication of water bodies is a challenge in many urban areas. This study measured and modelled quantitatively the pollutant nutrient load of an urban lake (80,596 m2), and assessed both external (constructed wetland) and internal (dredging) eutrophication extenuation measures. For the past 25 years, there has been redistribution (p &amp;lt; 0.005) of the lake's catchment land use, with built-up area increasing by 78.5%, and a reduction in vegetated (37.2%) and water surface (1.8%) areas. A 92.2% reduction in the lakes receiving wetland footprint (p = 0.000003) was noted, with increased nutrient load. The lake's light attenuation was found to be dominated by algae, limited by nitrogen and classified under the oligotrophic class (Trophic State Index &amp;lt; 40), with a threat of eutrophication in an estimated 25 years. Scenario analyses show that the construction of a wetland in the remaining 0.54 hectares of natural wetland will reduce total phosphorus by 35% and total nitrate by 45% (p = 0.05), whereas dredging the lake could reduce them by 80% each (p = 0.0005). Watershed management is the only sustainable solution to control nutrient flow into the lake and enable self-cleansing, factoring in the design of the receiving wetland and groundwater sources.

Road salt intrusion dynamics in an ex-urban native wetland complex

Inland freshwater wetlands throughout the northern U.S. and Canada are experiencing an increase in salinity due to road salt runoff during winter months. Salinization affects soil texture, contaminant transport, microbial activity, and plant growth in wetlands. Therefore, there is a pressing need to understand the dynamics of road salt intrusion in urbanized freshwater ecosystems. We used distributed high-resolution sensors to evaluate the dynamics of road salt intrusion into a wetland complex, Gensburg Markham Prairie (GMP), located in the ex-urban area outside Chicago, Illinois (USA). The in situ sensors measure electrical conductivity (EC), surface and groundwater level, precipitation, water temperature, and air temperature at 30-minute intervals. Water samples were collected monthly from 13 shallow groundwater wells and eight surface water locations and analyzed for Cl-, Mg2+, Na+, Ca2+, and K+. Two-years of continuous data show periodic spikes in EC during winter months, generally by an order-of-magnitude, due to intrusion of road salt applied on nearby roads. However, this behavior was not evident from monthly water samples, indicating that traditional water quality sampling methods likely miss such abrupt salt intrusion dynamics caused by rapid snowmelt runoff events. Higher levels of EC and Cl- occurred at the periphery of GMP near roadways, as well as in a preferential flow path to the interior of the wetland. Spectral analysis of EC time-series in ditches suggests that there is no correlation between salinity dynamics at super-annual timescales. This indicates that the salinity dynamics at GMP are event-driven, and the introduced solutes are rapidly exported from the site. This research supports development of improved de-icing strategies by local agencies and informs site-specific management of wetland ecosystems under anthropogenic stressors.

The effects of environmental empathy and sustainable intelligence on wetland tourists’ revisit intention using an extended model of goal-directed behavior

Although environmental empathy and sustainable intelligence have been identified as important concepts, relatively few researches have been conducted to explore their roles in wetland park tourists' decision-making process. Hence, in order to address this gap, the present study develops an extended model of goal-directed behavior, and then conducted a sequential and mixed research approach based on a quantitative survey(n = 353) and qualitative interviews(n = 60) to explore the formation of tourists' intention of revisiting a wetland park. Specifically, three critical constructs (i.e., environmental empathy, sustainable intelligence, and pro-environmental tourism behavior) were incorporated into the extended model of goal-directed behavior (MGB). And an onsite survey was conducted for tourists (n = 353) who visited six national wetland parks in Chongqing province of China. The proposed model was examined using structural equation modeling. Quantitative analysis reveals that the three critical constructs formed positive and significant causal relationships with the constructs in original MGB, and all the constructs in the original MGB were significant predictors of revisit intention. Quantitative and qualitative analysis have revealed that both environmental empathy and sustainable intelligence positively influence tourists’ revisit intention while sustainable intelligence (0.043) has a greater impact on this process than environmental empathy(0.029). Desire acted an important mediating role between antecedents of MGB and behavioral intention. Understanding tourists' psychology and Behavior is beneficial for park practitioners' marketing strategies improvement and sustainable tourism development. The findings of this study will not only enrich the theory of traveler behavioral intention, but also expand the model of goal-directed behavior under natural-based destination sites.

Comparative analysis of the gut microbiota of wild wintering whooper swans (Cygnus Cygnus), captive black swans (Cygnus Atratus), and mute swans (Cygnus Olor) in Sanmenxia Swan National Wetland Park of China.

The gastrointestinal microbiota, a complex ecosystem, is involved in the physiological activities of hosts and the development of diseases. Birds occupy a critical ecological niche in the ecosystem, performing a variety of ecological functions and possessing a complex gut microbiota composition. However, the gut microbiota of wild and captive birds has received less attention in the same region. We profiled the fecal gut microbiome of wild wintering whooper swans (Cygnus Cygnus; Cyg group, n = 25), captive black swans (Cygnus Atratus; Atr group, n = 20), and mute swans (Cygnus Olor;Olor group, n = 30) using 16S rRNA gene sequencing to reveal differences in the gut microbial ecology. The results revealed that the three species of swans differed significantly in terms of the alpha and beta diversity of their gut microbiota, as measured by ACE, Chao1, Simpson and Shannon indices, principal coordinates analysis (PCoA) and non-metricmulti-dimensional scaling (NMDS) respectively. Based on the results of the linear discriminant analysis effect size (LEfSe) and random forest analysis, we found that there were substantial differences in the relative abundance of Gottschalkia, Trichococcus, Enterococcus, and Kurthia among the three groups. Furthermore, an advantageous pattern of interactions between microorganisms was shown by the association network analysis. Among these, Gottschalkia had the higher area under curve (AUC), which was 0.939 (CI = 0.879-0.999), indicating that it might be used as a biomarker to distinguish between wild and captive black swans. Additionally, PICRUSt2 predictions indicated significant differences in gut microbiota functions between wild and captive trumpeter swans, with the gut microbiota functions of Cyg group focusing on carbohydrate metabolism, membrane transport, cofactor, and vitamin metabolism pathways, the Atr group on lipid metabolism, and the Olor group on cell motility, amino acid metabolism, and replication and repair pathways. These findings showed that the gut microbiota of wild and captive swans differed, which is beneficial to understand the gut microecology of swans and to improve regional wildlife conservation strategies.

Non-Negligible Ecological Risks of Urban Wetlands Caused by Cd and Hg on the Qinghai-Tibet Plateau, China.

The Huangshui National Wetland Park (HNWP) is a unique national wetland park in a city on the Qinghai-Tibetan Plateau, containing three zones: Haihu, Beichuan, and Ninghu. In this study, a total of 54 soil samples (18 sampling points with depths of 0-10 cm, 10-20 cm, and 20-30 cm) were collected in these three zones, and the contents of heavy metals (Cr, Cd, Cu, Hg, Ni, Pb, Zn, and As) of each sample were determined. The ecological risk of eight kinds of heavy metals was evaluated by using the geo-accumulation index (Igeo), and the ecological risk-controlling effect of the Xining urban wetlands on heavy metals was explored by comparative analysis, and the possible sources of heavy metals in the soil were analyzed via correlation analysis and principal component analysis (PCA). The results revealed that the total heavy metal concentration order was Haihu > Beichuan > Ninghu zone. As and Cu presented vertical accumulation characteristics in the surface and lower horizon, respectively. Cr, Cd, Hg, Ni, Pb, and Zn accumulated downwards along the depth. On the spatial scale, the enrichments of Cd and Hg brought non-negligible ecological risks in plateau urban wetlands. The results of PCA indicated that soil heavy metals mainly came from compound sources of domestic and atmospheric influences, traffic pollution sources, and industrial pollution sources. The study has revealed that human activities have inevitable negative impacts on wetland ecosystems, while the HNWP provides a significant weakening effect on heavy metal pollution.

Simulation on TN and TP Distribution of Sediment in Liaohe Estuary National Wetland Park Using MIKE21-Coupling Model

A hydrodynamic-water quality model was established using MIKE21 to analyze the distribution of total nitrogen (TN) and total phosphorus (TP) in the wetland sediments of Liaohe Estuary National Wetland Park. The purpose of this model is to investigate the spatial and temporal variation patterns in wetland sediments and the distribution of pollutant contents. The research determines the applicability of this model in accurately predicting these patterns. The simulated contour map of the water quality concentration displays significant variation characteristics and reflects the actual concentration of pollutants in the wetland sediment of the Liaohe Estuary, proving the coupled model to be reasonable and accurate. The water quality simulation results indicate that water flowing through the wetland aids in purifying pollutants in the sediment, and the purification effect is more significant during the flood season. The MIKE21 model’s treatment reveals that the content of TN in wetland sediments decreases from southwest to northeast in the surface layer, following the flow direction of surface water. As the depth increases, the content of TN also decreases, with the bottom layer showing a decrease from southwest to northeast. The TP in wetland sediments receives surface water runoff and diffuses from upstream to downstream. The content of TP gradually decreases with increasing depth.

Numerical modeling of wave attenuation: implications of representing vegetation found in coastal saltmarshes in the Chesapeake Bay.

Coastal communities are vulnerable to wave and storm surges during extreme events, highlighting the need to increase community resilience. The effectiveness of natural wetlands in attenuating waves is vital to designing strategies for protecting public safety. This study aimed to understand how vegetation attenuates waves and determine the best method for modeling vegetation's impact on wave dynamics. The researchers compared two different vegetation representations in numerical models, implicit and explicit, using SWAN and XBeach at varying spatial resolutions. The study focused on two marshes in the Chesapeake Bay, using field measurements to investigate the accuracy of each method in representing wave attenuation by vegetation and the implications of explicitly representing average characteristics of one vegetation species on a regional level. Results showed that explicit modeling using average vegetation characteristics provided more accurate results than the implicit model, which only showed wave attenuation due to topography. The finer scale resolution and site-specific vegetation characteristics further improved the accuracy of wave attenuation observed. Understanding the trade-offs between different vegetation representations in numerical models is essential to accurately represent wave attenuation and design effective protection strategies for coastal communities.

Effect of a natural wetland on the removal of antibiotics and antibiotic resistant bacteria in a treated sewage treatment effluent

Antibiotics are often released into the environment via disposal or excretion. A selection pressure is then initiated that leads to the acquisition of antibiotic resistance genes (ARGs) in environmental bacteria, thus encouraging the environmental spread of antibiotic resistance. The purpose of this study was to examine the nutrient and antibiotic reducing capacity of the Point au Chene assimilation wetland that receives the city of Thibodaux, Louisiana, USA treated sewage wastewater. Water samples were collected from four sampling sites along the wetland every month from May 2022 to April 2023. Water quality was assessed at each stage of flow within the wetland including the direct discharge (input) site, wetland midpoint, wetland endpoint, and a control site adjacent to the Thibodaux Sewage Plant, but separated by a hardwood ridge that prevents the intrusion of treated effluent. Standard water quality parameters, coliform bacteria, and antibiotic concentrations were determined. Results indicated antibiotic, coliform, nitrate, sulfate, and ammonia concentrations were significantly higher at the input site than other wetland sites. The antibiotics, tetracycline and sulfamethoxazole were reduced by 75 % in the wetlands. More than 80 % of penicillin and bacitracin were removed throughout the wetland. The input site additionally expressed the highest amount of multi-drug resistance and bacterial diversity of all sites. ARGs have been identified throughout the wetland system, with bacterial isolates testing positive for the ARGs bacA, sul2, and tetA, coding for resistance to bacitracin, sulfonamide, and tetracycline antibiotics respectively. The wetland has a positive impact of reducing the nutrients, antibiotics, and ARB in the treated sewage prior to release to adjacent waterbodies.