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Coastal tidal wetlands are crucial for environmental and economic health, but facing threats from various environmental changes. Detecting changes of tidal wetlands is essential for promoting sustainable development in coastal areas. Despite extensive researches on tidal wetland changes, persistent challenges still exist. Firstly, the high similarity among tidal wetland types hinders the effectiveness of existing common indices. Secondly, many current methods, relying on hand-crafted features, are time-consuming and subject to personal biases. Thirdly, few studies effectively integrate multi-temporal and semantic information, leading to misinterpretations from environmental noise and tidal variations. In view of the abovementioned issues, we proposed a novel temporal-spectral-semantic-aware convolutional transformer network (TSSA-CTNet) for multi-class tidal wetland change detection. Firstly, to address spectral similarity among different tidal wetlands, we proposed a sparse second order feature construction (SSFC) module to construct more separable spectral representations. Secondly, to get more separable features automatically, we constructed temporal-spatial feature extractor (TSFE) and siamese semantic sharing (SiamSS) blocks to extract temporal-spatial-semantic features. Thirdly, to fully utilize semantic information, we proposed a center comparative label smoothing (CCLS) module to generate semantic-aware labels. Experiments in the Greater Bay Area, using Landsat data from 2000 to 2019, demonstrated that TSSA-CTNet achieved 89.20% overall accuracy, outperforming other methods by 3.75%–16.39%. The study revealed significant area losses in tidal flats, mangroves, and tidal marshes, decreased by 3148 hectares, 35 hectares, and 240 hectares, respectively. Among the cities in GBA, Zhuhai shows the most significant area loss with a total of 1626 hectares. TSSA-CTNet proves effective for multi-class tidal wetland change detection, offering valuable insights for tidal wetland protection. [ABSTRACT FROM AUTHOR]

Spartina alterniflora has rapidly and extensively encroached on China's coastline over the past decades. Among the coastal areas invaded by S. alterniflora , at most 93% are mudflats. However, the effect of S. alterniflora invasion on soil organic carbon (SOC) stocks of coastal mudflats has not been systematically studied on a national scale. Here, we quantified the nationwide changes in SOC stocks in coastal mudflats associated with S. alterniflora invasion between 1990 and 2020. We found that S. alterniflora invasion significantly enhanced SOC stocks in coastal China. Nonetheless, the benefit of S. alterniflora invasion of coastal SOC stock may be weakened by continuing human intervention. We found that S. alterniflora invading mudflats added 2.3 Tg SOC stocks to China's coastal blue carbon, while 1.78 Tg SOC stocks were lost mainly due to human activities, resulted in a net SOC stock gain of 0.52 Tg C. These findings overturned the traditionally thought that S. alterniflora invasion would reduce ecosystem services by highlighting that the historical invasion of S. alterniflora has broadly and consistently enhanced blue carbon stock in coastal China. [ABSTRACT FROM AUTHOR]

• A Suaeda Salsa spectral index (SSSI) is proposed. • SSSI can be used for both S. salsa mapping and fractional cover (FC) estimation. • S. salsa with FC as low as 20% can be accurately detected. • SSSI performs better than NDVI and SAVI for S. salsa FC estimation. • SSSI alleviates the impact of heterogeneous soil backgrounds in intertidal wetlands. Suaeda Salsa (S. salsa), with short and red-purplish plants, is a typical pioneer saltmarsh species in the intertidal wetlands of temperate East Asia. It has important ecological, economic, and recreational values. In the past few decades, S. salsa has severely degraded in coastal China, which has brought widespread attention from regional and local governments. As a result, extensive S. salsa restoration projects have been initiated in recent years. It is urgently needed to develop satellite-based methods for both S. salsa mapping and fractional cover (FC) estimation because degradation and recovery of S. salsa are manifested by changes in both area and plant cover. However, accurate mapping and FC estimation of S. salsa are challenging because (1) S. salsa in intertidal areas have low FC and (2) heterogeneous soil backgrounds in wetlands greatly impact the spectral reflectance observed by satellites. To address these issues, this study proposed a new Suaeda Salsa Spectral Index (SSSI) to support accurate detection and FC estimation of S. salsa. The SSSI was designed based on the laboratory spectral measurements by considering variations in wetland soil moisture and by taking advantage of the reddish color of S. salsa. It consists of two components, one of which utilized blue, green and red bands to separate S. salsa from green vegetation, and the other component utilized a modification of the Soil Adjusted Vegetation Index (SAVI) to reduce the impact of soil background and maintain a linear relationship with S. salsa FC. SSSI was then applied on Sentinel-2/GF-1 images over the Yellow River Delta (YRD) and Liao River Delta (LRD), China. Based on SSSI, a simple thresholding approach was used to identify S. salsa, and a linear regression model was used to estimate FC. With reference datasets provided from field investigations, Unmanned Aerial Vehicle multispectral images and high-spatial resolution satellite images, our results show that the SSSI was able to detect low-coverage S. salsa (FC > 20 % in YRD and FC > 10 % in LRD), and the S. salsa maps had an overall accuracy over 94%. The SSSI-FC models achieved good estimation accuracies (R2 = 0.77 ∼ 0.86, RMSE = 7.55 % ∼ 9.79 %). Compared to the Normalized Difference Vegetation Index (NDVI) and SAVI, SSSI alleviated the impacts from soil backgrounds and provided better S. salsa FC estimations, particularly for low-coverage S. salsa. SSSI has great potential in supporting continuous monitoring of S. salsa dynamics and evaluating the effectiveness of S. salsa restoration projects. [ABSTRACT FROM AUTHOR]

Cities worldwide face resilience challenges as climate risks interact with rapid urbanization, loss of biodiversity and ecosystem services, poverty, and Socioeconomic inequality. This leads to the social, physical, and economic collapse of cities and their systems. Over time, urban resilience challenges are expected to increase, driven by urbanization, land use, and climate change. It is for this reason that the concept of urban resilience is increasingly attracting the attention of governments, and urban planners. Gray infrastructure is not always suitable for profitability, resilience, or sustainability. Now more than ever, green infrastructure is recognized as a nature-based solution (NBS) that plays a significant role in addressing resilience challenges in urban areas. These solutions can be applied through spatial measurements and parameters in and around the city. Constructed wetlands (Cws) are artificial imitations of natural wetlands, one of the most biologically diverse natural ecosystems, and in addition to aesthetics, It provides an effective model for resilient environmental engineering solutions as a low-cost and easy-to-operate alternative to traditional urban management systems. Consequently, the main objective of this research was to define criteria for integrating constructed wetlands (Cws) into the urban landscape as nature-based solutions (NBS) and address the limitations and maximize advantages as well as contribute to replicate best practices of constructed wetlands (Cws) in different Zones (Desert, River's floodplain, coastal) in Egyptian cities for enhancing the urban resilience. [ABSTRACT FROM AUTHOR]

Wetlands are one of the most important ecosystems on the Earth, and using hyperspectral remote sensing (RS) technology for fine wetland mapping is important for restoring and protecting the natural resources of coastal wetlands. However, the high cost in collecting labeled samples and inconsistent acquisition conditions across different geographic regions or scenes lead to difficulties in wetland mapping and classification. To mitigate these difficulties, a spatial–spectral weighted adversarial domain adaptation (SSWADA) network is proposed for the cross-scene wetland mapping using hyperspectral image (HSI). The proposed SSWADA employs an idea of weighted adversarial discrimination to align the feature distribution of source and target scenes, where a generator or feature extractor with joint 2D–3D convolution is used to extract spatial–spectral features of HSI, a weighted discriminator is constructed to perform source instance weighting and a multi-classifier structure is designed to improve the classification performance on target samples. Experimental results on four different tasks show that our SSWADA outperforms existing domain adaptation methods for cross-scene wetland mapping. [ABSTRACT FROM AUTHOR]

• The risk of toxic metals in sediments were assessed at different depths. • Pb and cd binding to surface sediments is mainly mediated by organic functional groups. • Mineral components were mainly bound to toxic metals in the bottom sediments. • Mineral compounds (Fe, Mn), Pb, and c functional groups were unevenly distributed. • The type and sequence of toxic metal binding changed with sediment depth. The excessive accumulation of potentially toxic metals (Pb and Cd) in coastal wetlands is among the main factors threatening wetland ecosystems. However, the effects of water table depth (WTD) on the risk and binding mechanisms of potentially toxic metals in sediments remain unclear. Here, sediments from different WTD obtained from a typical coastal wetland were evaluated using a newly developed strategy based on chemical extraction methods coupled with high-resolution spectroscopy. Our findings indicated that the WTD of the coastal wetland fluctuates frequently and the average enrichment factor for Pb was categorized as minor, whereas Cd enrichment was categorized as moderate. High-resolution spectroscopy techniques also demonstrated that organic functional groups and partly inorganic compounds (e.g., Fe-O/Si-O) played a vital role in the binding of Pb and Cd to surface sediments. Additionally, mineral components rather than organic groups were mainly bound to these metals in the bottom sediments. Collectively, our findings provide key insights into the potential health effects and binding characteristics of potentially toxic metals in sediments, as well as their dynamic behavior under varying sediment depths at a microscale. [Display omitted] [ABSTRACT FROM AUTHOR]

Great Lakes coastal wetlands serve as mediation zones between the land and the lake, regulating the fate of materials received from tributaries prior to discharge to the lake nearshore zone. To improve our understanding of water quality processing and nutrient fate in coastal wetlands, we evaluated within- and across-wetland water quality as a function of environmental drivers over a decade (2009–2018) in three drowned river mouth (Carruthers, Duffin's, and Rouge) and one barrier lagoon (Frenchman's Bay) wetlands on the north shore of Lake Ontario. Overall, land-use had a weak relative association with most water quality parameters, reflecting no appreciable changes in land-use across the study years. The barrier lagoon wetland Frenchman's Bay had a distinctly different water quality pattern from the drowned river mouth wetlands, where water quality followed a high to low concentration gradient from near the tributary confluences (high) to the lake-wetland confluence (low) (permutational analysis of variance p-value < 0.001). Notably, we observed significant differences among celled (i.e., natural ponds in wetlands) and non-celled sites in Duffin's and Rouge marshes, primarily attributed to strong covariation among phosphorus, phosphate, and organic nitrogen concentrations (permutational analysis of variance p-value < 0.001). This water-quality signature seemed to be driven by solar radiation and lake level variability (i.e., seiche inundation), inferring that wetlands may be important sites for the mobilization of legacy phosphorus in sediments under certain climatic conditions, and following seiche events. [ABSTRACT FROM AUTHOR]

A likely consequence of sea level rise during the next century will be progressive inundation of seawater through the current unsaturated zone in coastal-margin soils. It is unclear how this will change the biogeochemical cycling of iron, sulfur and carbon over different time scales and soil types. A long-term (540 day) laboratory experiment, slowly inundating intact coastal soil cores with seawater from the 'bottom up', was conducted to observe how coupled iron and sulfur dynamics change in different soil types. Pore water was extracted from the 60 cm cores at 10 cm depth intervals every 90 days and analysed for pH, electrical conductivity (EC), Fe2+, HS − and dissolved metals (Fe, Mn, As, Cd, Cu, Ni, Pb, Co, Zn) as well as stable sulfur (34S/32S) and radiogenic strontium (87Sr/86Sr) isotopes. Destructive solid phase analyses (for reactive Fe, acid volatile and chromium reducible sulfur (AVS and CRS) and total organic carbon (TOC)) were made at the start and end of the experiment. Iron and sulfate reduction was induced in soils with readily available TOC as anoxic conditions established, evidenced by statistically significant increases (P < 0.001) in dissolved Fe2+ and sulfide concentrations in porewaters, as well as simultaneous and progressive increase in the sulfur isotope (34S/32S) ratios. An increase in AVS indicated formation of metastable iron sulfide (FeS) minerals resulting from Fe2+ and sulfide in porewaters post inundation. This was supported by PHREEQC modelling of local mineral saturation states/indices in the system. Overall, the Fe2+ concentration increased to a peak at between 270 and 360 days, and then began decreasing at some depths, indicating slowing iron reduction, presumably because reactive iron (oxyhydro)oxides became progressively consumed by microbially driven reductive processes. However, microbially mediated sulfate reduction continued as abundant sulfate was still available from seawater. In the absence of free Fe2+, sulfide accumulated in the porewater, but only in those soils inundated the longest (>360 days), and with greater than 5% TOC. The combined use of sulfur (34S/32S) and strontium (87Sr/86Sr) isotopes supported the observed results, and represents a new and robust technique to quantify progressive sulfate reduction and seawater mixing phenomena in coastal soils. This study gives new insights into the biogeochemical cycling of sulfur and iron in soils experiencing seawater inundation from sea level rise over longer timescales. It is likely that sulfidisation (due to in-situ sulfate reduction) will begin to affect coastal wetland soils, especially in areas where TOC is high and where reactive iron depletes over time. This has potential consequences for sulfide toxicity in coastal soils and environments globally. [ABSTRACT FROM AUTHOR]

The ability of microbial communities to respond to and degrade crude oil in marine environments is well understood, yet fewer studies have examined freshwater environments. The Laurentian Great Lakes are one of the world's largest surface freshwater sources. A pipeline that transports light synthetic crude oil crosses between two of the Great Lakes (the Straits of Mackinac, connecting Lakes Michigan and Huron, U.S.A.), and there is uncertainty on how the various habitats within this region would respond to accidental crude oil exposure. In this study, sediment microbial communities from three distinct habitats (coastal beach, freshwater coastal wetland, and Lake Michigan deep sediments) were used in microcosm experiments to document their community response (16S rRNA gene sequencing) to light synthetic crude oil (headspace gas chromatography). Microbial community structure (beta diversity) was impacted after exposure to crude oil in each of the habitats examined, with each habitat showing a different level of resistance to crude oil. Additionally, within each habitat, beta diversity distinguished sub-communities that increased in abundance in experimental treatments. Specifically, an increase in total abundance of Alphaproteobacteria , Betaproteobacteria , or Gammaproteobacteria was observed in microcosms exposed to crude oil regardless of habitat type. Methane, a potential hydrocarbon degradation byproduct, was observed in the headspace of the microcosms after exposure to crude oil, which may indicate methanogenic hydrocarbon degradation. These data suggest Great Lakes freshwater microbial communities will respond differently to crude oil exposure but may have shared community members involved in resisting and degrading light synthetic crude oil. [ABSTRACT FROM AUTHOR]

The ecosystem services concept has been slow to integrate into written law and policy in Australia. We sought to examine whether the concept has permeated deeper into practice, focusing on the coastal wetland protection, management and restoration context. We conducted a Delphi study involving 16 key informants. Over two rounds of interviews we found confirmation that the ecosystem services concept is not a central part of practice, and a strong consensus support for integrating and mainstreaming ecosystem services into law and policy through law reform. Our informants also provided additional new insights on how reform should proceed: (1) integration may occur through consolidated or interconnected law and policy instruments, (2) decision-maker discretion should be retained but subject to constraints, especially regarding (3) trade-offs between different ecosystem services and ecosystem services and other land uses. Our informants also called for (4) more effective and targeted policy to facilitate restoration projects, (5) incentivised protection and restoration across land tenure types, especially on privately-owned land and (6) caution in dealing with trade-offs and financial valuations of ecosystem services. The insights provided through this Delphi study will be instructive for law and policy reform in Australia and other jurisdictions grappling with fragmented management, protection and restoration of coastal wetlands. • Practice shows that the ecosystem services concept is not central to law, policy or decision-making about coastal wetlands. • There is strong consensus support for incorporating the ecosystem services concept into law and policy. • However care should be taken when dealing with trade-offs and financial valuations of ecosystem services. [ABSTRACT FROM AUTHOR]

Seagrass beds offer unique and vital ecological services as an important blue carbon ecosystem in coastal wetlands. Zostera japonica is an intertidal seagrass species native to eastern Asia and is one of the most widely distributed seagrass species in China. However, little is known on the long-term variations of Z. japonica extents. Automatic mapping method for Z. japonica seagrass beds is in urgent need to fill this knowledge gap. In this study, we proposed a new SeaGrass Index (SGI) for automatic and rapid mapping of Z. japonica based on time-series Landsat satellite imagery, aiming to alleviate the influence of tidal inundation and enhance the separability from other coastal cover types. The SGI considers both spectral and phenological characteristics of Z. japonica , as well as the spatial location of Z. japonica. We took the Yellow River Delta (YRD), China as our study area, where Z. japonica was first discovered and reported in 2015. Based on SGI, Z. japonica extents during 1985–2018 were extracted using multi-Otsu thresholding algorithm. Accuracy assessments based on field investigations and high-resolution imagery showed that SGI successfully separated seagrass beds from other cover types, especially intertidal salt marshes, with overall accuracies > 95%, producer's accuracies > 90% and user's accuracies > 94%. Our study provides the first long-term maps of seagrass beds in YRD. The area of Z. japonica showed large variations during 1985–2018, ranging from 149 ha in 2005–2006 to 1302.9 ha in 2011–2012. The spatial distribution of Z. japonica varied with the morphological change of the estuary caused by river channel shifts. Since 2011, Z. japonica seagrass beds have undergone area degradation due to the invasion of S. alterniflora. The area was only 332.3 ha in 2017–2018. Coastal erosion and extreme climate events such as drought and typhoon might also explain degradation of seagrass beds in YRD. We expect that the SGI will advance automatic and rapid mapping methods for intertidal seagrass beds, and the Z. japonica maps will provide a baseline data for restoration and management of seagrasses at regional scale. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) pollution has gained significant attention in mangrove sediments due to its high toxicity and mobility. However, the sources of Cd and the factors influencing its accumulation in these sediments have remained elusive. In this study, we utilized lead (Pb) isotopic signatures for the first time to assess Cd contamination in mangrove sediments from the northern region of the Beibu Gulf. A strong correlation was observed between Cd and Pb concentrations in the mangrove sediments, suggesting a shared source that can be estimated using Pb isotopic signatures. By employing a Bayesian mixing model, we determined that 70.1 ± 8.2 % of Cd originated from natural sources, while 12.9 ± 4.9 %, 9.8 ± 3.7 %, and 7.1 ± 3.4 % were attributed to agricultural activities, non-ferrous metal smelting, and coal combustion, respectively. Our study clearly suggests that natural Cd could also dominate the high Cd content. Agricultural activities were the most important anthropogenic Cd sources, and the increased anthropogenic Cd accumulation in mangrove sediment was related to organic matter. This study introduces a novel approach for assessing Cd contamination in mangrove sediment, providing useful insights into Cd pollution in coastal wetlands. [Display omitted] • Cd and Pb concentrations in mangrove sediment were significantly correlated. • Source contribution of Cd was estimated by Pb isotopic signatures. • Natural source can dominate the Cd content in the mangrove sediment. • Elevated anthropogenic Cd accumulation in mangrove sediment was related to organic matter. [ABSTRACT FROM AUTHOR]

• Total nitrogen was a key driver in soil CH 4 and CO 2 production in tidal marshes. • Nitrate enrichments tended to decrease CH 4 and CO 2 production. • Nitrate but not ammonium addition decreased mcr A gene abundance. • Salinity was not a mitigating factor in either nitrogen eutrophication scenarios. Eutrophication is an important environmental stressor in coastal wetlands that alters ecosystem processes including primary production and the carbon cycle. However, how different nitrogen eutrophication scenarios may affect CH 4 and CO 2 production along a salinity gradient in coastal wetlands is poorly known. We collected the surface soil samples from both tidal freshwater and mesohaline Phragmites australis marshes in six main estuaries in China and conducted inorganic nitrogen enrichment anaerobic incubation experiments. Background soil CH 4 and CO 2 production rates were strongly correlated with total nitrogen but not salinity. On average, nitrate enrichment decreased soil CH 4 and CO 2 production rates by ca. 20 % in freshwater marsh and 16–43 % in mesohaline marshes, whereas ammonium enrichment decreased CO 2 production by ca. 26–30 % but had no effect on CH 4 production. Salinity was not an important mitigating factor in either eutrophication scenario. In most cases, nitrogen addition decreased the extracellular enzyme activities of β-1,4-glucosidase and cellobiohydrolase, but increased the activity of β-N-acetyl glucosaminidase, phenol oxidase and peroxidase. Nitrate addition decreased the mcr A gene abundance on average by 34–35 % but ammonium addition had insignificant effect. Total nitrogen availability was an important driver of CH 4 and CO 2 production rates in these tidally influenced coastal wetlands. Our results showed that tidal marshes with salinity < 15 ppt had similar soil CH 4 production rates, and increasing inorganic nitrogen eutrophication might lower soil microbial carbon gas production in both tidal freshwater and mesohaline marshes. [ABSTRACT FROM AUTHOR]

• Organic carbon (OC) distribution and sources were evaluated in estuarine mangrove wetlands. • OC contents and storage decreased from upstream to downstream. • Mangrove-derived OC contribution increased with tidal level, while marine and terrestrial OC contributions decreased. • Mangrove leaves and roots infiltration led to the dominance and preservation of mangrove OC in soils. Coastal wetlands are increasingly recognized for their role in climate change mitigation, particularly through the sequestration of soil organic carbon (SOC). Despite widespread acknowledgement of their importance, the variation in organic carbon (OC) sources among different estuarine mangrove wetlands, and how these sources interact with environmental factors, is not fully elucidated. This research focuses on the role of estuarine mangrove wetlands in climate change mitigation through SOC sequestration. It explores the distribution, sources, and decomposition of SOC in a wetland with four mangrove communities along a tidal gradient. These include a tidal flat, a Sonneratia apetala forest, a mixed S. apetala and Kandelia obovata forest, and a K. obovata forest. The study employs biogenic element analysis (C, N, lignin phenols) and natural stable carbon isotope ratios (δ13C and δ15N) to assess SOC. Key findings show a decrease in SOC and total nitrogen (TN) from the upstream K. obovata forest to the downstream tidal flat. A stable isotope mixing model reveals a diminishing mangrove-derived OC contribution in topsoil (0–40 cm), estimated at 62 % in the K. obovata forest, 45 % in the central region, and 24 % in tidal flats. Soil profiles suggest microbial decomposition as the main isotope fractionation mechanism, with lignin analysis indicating woody angiosperms as the primary OC source. These findings enhance understanding of OC origins and decomposition in coastal wetlands and inform "blue carbon" management, highlighting the terrestrial-estuary continuum's significance. [ABSTRACT FROM AUTHOR]

• Hydrological export of the five main carbon components from a restored saltmarsh wetland were measured. • Groundwater-driven fluxes of alkalinity, DIC, DOC, CO 2 , and CH 4 were estimated using radon. • The contribution of groundwater to surface water carbon export was determined. • SW and GW carbon exports from the restored wetland were lower than those reported for natural wetlands. Coastal wetlands play a crucial role in the global carbon cycle, yet they have been extensively degraded over the past decade. Though restoration efforts are underway worldwide, there is limited understanding of the role groundwater plays in transporting dissolved carbon within restored wetlands. Here, we address this knowledge gap by investigating water and carbon fluxes in the restored Tomago Wetlands in coastal NSW, Australia. We aim to 1) quantify surface water exports of the main carbon components, 2) estimate greenhouse gas emissions from the aquatic parts of the wetland, and 3) determine the contribution of groundwater discharge to the surface water carbon export and greenhouse gas emissions from the wetland. Sampling took place following a wet period and a freshening event. A radon mass balance model estimated groundwater discharge contributing 10 % to the surface water flow in the restored wetland. The wetland was a source of four of the five main carbon components including DOC, DIC, alkalinity, and CO 2 , with most of the exported carbon being in the form of alkalinity. Surface water DOC, DIC, alkalinity, and CO 2 exports were, 1.3 ± 0.5, 35.5 ± 13.1, 39.4 ± 14.6 and 6.5 ± 2.1 mmol/m2/d, respectively. The average water to atmosphere flux of CO 2 and CH 4 were 104 ± 209 (mmol/m2/d) and 21 ± 42 (µmol/m2/d). Groundwater-driven carbon fluxes contributed 100 % of the surface water DOC, 30 % of the DIC, 15 % of the alkalinity exports, and 5 % of the overall CO 2 losses (lateral aqueous export + atmospheric emissions) from the wetland, with minor contributions to CH 4. Carbon exports from both the wetland and groundwater observed in this restored wetland were found to be lower than those reported in the literature for natural or mature wetlands. This would have important implications when developing carbon accounting methods. Overall, our findings highlight the importance of groundwater in carbon transport within restored wetlands and emphasise the need for inclusion of shallow groundwater dynamics in carbon budgets and inventories of coastal wetlands that have or will undergo restoration. [ABSTRACT FROM AUTHOR]

Restoration of coastal wetland vegetation faces hurdles from salinity and alkalinity, especially due to high total soil phosphorus (P) with low bioavailability. P-solubilizing bacteria (PSB) can aid by converting organic and inorganic P forms into bioavailable phosphate. However, PSB's impact on nutrient availability and plant growth in coastal soils remains unclear due to salinity-alkalinity interactions. Potted Experiments used Suaeda salsa inoculated with salt-alkaline-tolerant PSB strains, Bacillus sp. DYS211 and Exiguobacterium sp. DYS212. Bacterial solution was applied to the soil twice during plant growth. Microbial diversity and composition in rhizosphere bacteria and fungi were studied, alongside soil properties and plant growth. PSB affected rhizosphere microbial composition but not diversity in non-stressed conditions. Under alkalinity, the microbial composition varied more than under salinity stress or mixed stress, suggesting the alkalinity's stronger influence. This is crucial for wetland ecosystem resilience. Microbial sensitivity to pH was reflected in diversity indices, notably a 20 % and 100 % increase in Shannon and Chao indices, respectively, under alkaline compared to salinity. Saline/alkaline stress was the primary driver of rhizosphere microbial diversity and composition, overshadowing PSB addition. Without salts, PSB inoculation decreased plant biomass by 4 % (DYS211) and 13 % (DYS212) due to limited P-solubilization. Under saline and alkaline stress, PSB inoculation decreased soil pH and increased available P, which shift in soil nutrient content then drove the microbial diversity and composition of the rhizosphere, thereby increasing resistance and consequently raised plant height and biomass. Soil total nitrogen (N), P, and potassium (K) ratios mainly shaped fungal communities, while pH and the ratios of ammonium, available P, and K primarily governed bacterial diversity and composition. It reveals specific ecological niches and strategies of fungi and bacteria. Regulating soil pH and nutrient ratios optimizes rhizosphere microbiome, ultimately promoting plant growth. [Display omitted] • PSB altered rhizosphere microbial composition but not diversity without salinity. • Saline/alkaline stress had a greater effect on rhizo-microbe than PSB inoculation. • PSB increased soil nutrient, drove rhizo-microbe, raised plant resistance and growth. • Ratios of total soil N, P, K primarily drove rhizosphere fungal communities. • Soil pH and ratios of available N, P, K controlled rhizosphere bacterial communities. [ABSTRACT FROM AUTHOR]

Coastal wetlands are vital carbon repositories with a substantial soil carbon storage potential; as such, they play a crucial role in global carbon sequestration and climate regulation. The most invasive species in the global coastal zone, Spartina alterniflora , has significantly affected the ecosystem functions and nutrient cycling of coastal wetlands. However, it is uncertain how S. alterniflora invasion affects the driving mechanism of greenhouse gas (GHG) emissions by causing changes in the soil labile organic carbon (LOC) pool. Therefore, we investigated the mediating role of soil LOC in influencing the impact of Spartina alterniflora invasion on soil GHG emissions. Our study was conducted in the coastal wetlands of the Dongtai Tiaozini Wetland Reserve in Yancheng, China. The relationship between variations in soil LOC components and GHG emissions in coastal wetlands was analyzed by measuring these variables across areas with high, moderate, and no invasion of S. alterniflora. The results showed that as the degree of invasion intensified, emissions of carbon dioxide (CO 2), nitrous oxide (N 2 O), and the global warming potential (GWP) showed significant increasing trends, while methane (CH 4) emissions tended to increase first and then decrease. Compared with CO 2 emissions in the non-invasive plots of S. alterniflora , CO 2 emissions in moderately and highly invasive plots increased by 166.68 % and 403.35 %, respectively (P < 0.05). Similarly, N 2 O emissions increased by 34.67 % and 303.03 %, respectively (P < 0.01), and the GWP increased by 683.87 % and 947.32 %, respectively (P < 0.01). For CH 4 emissions, moderate invasion represented a carbon source, and high invasion represented a carbon sink. The findings indicated that S. alterniflora invasion alters GHG emissions by modifying the soil LOC components and the ratio of LOC to soil organic carbon. These results provide a robust data foundation for understanding changes in carbon cycling and predicting feedback mechanisms on climate change in the context of S. alterniflora invasions in coastal wetlands. [ABSTRACT FROM AUTHOR]

Understanding the long-term dynamics of saltmarsh vegetation and their driving factors is crucial for the restoration of degraded coastal wetlands. Reclamation and plant invasion, identified as the two most significant environmental contributors to saltmarsh vegetation degradation, profoundly influence the evolution of saltmarsh vegetation. However, the long-term impacts of reclamation and plant invasion on native saltmarsh vegetation remain unclear. This study utilized multi-source time series remote sensing data to quantify the long-term impacts of Spartina alterniflora invasion and reclamation on native saltmarsh vegetation in the Yangtze River estuary from 1985 to 2020. Unlike other studies, this study generated annual saltmarsh cover data using image composite, zoning classification, object-based phenology algorithm, and random forest algorithm, which largely addressed the problem that existing studies could not capture transient change and gradual change because of insufficient observation frequency. Results showed that: (1) Reclamation had resulted in a loss of 503.93 km2 of native saltmarsh vegetation from 1985 to 2020, including 286.16 km2 of Phragmites australis community and 217.77 km2 of Scirpus spp. community; Spartina alterniflora invasion had resulted in a loss of 78.96 km2 of native saltmarsh vegetation from 1985 to 2020, including 12.48 km2 of Phragmites australis community and 66.48 km2 of Scirpus spp. community; (2) Significant differences of spatial-temporal evolution patterns of native saltmarsh vegetation were observed under different degrees of Spartina alterniflora invasion and reclamation, including irrecoverable scenario under severe plant invasion and excessive reclamation, recoverable scenario under moderate degree of reclamation and plant invasion, and competitive scenario under plant invasion and without reclamation.; (3) From a long-term remote sensing perspective, spread limitation determined by reclamation intensity was a decisive factor in the evolution of Phragmites australis community in the study area, while interspecific competition between invasive Spartina alterniflora and Scirpus spp. determined the evolution of Scirpus spp. community. This study provides a theoretical basis and baseline for the protection strategies of native saltmarsh vegetation in the study area. [ABSTRACT FROM AUTHOR]

Natural estuarine wetland shorelines play a crucial role in coastal stabilization and preserving ecological security patterns. The effectiveness of estuarine shoreline engineering in reducing coastal erosion and maintaining the stability of ecosystem structures and functions is tightly linked to their types and structures. Although the living estuarine shorelines have received increasing attention, there have been few systematic literature reviews on the development process, research hotspots and future trends in this field. Here we summarized the literatures, and analyzed them in terms of annual publications, subject categories, co-cited journals, countries, institutions, authors, references, and keywords based on OriginPro, VOSviewer, and CiteSpace softwares. Results showed that the studies on living estuarine shorelines have experienced a rapid development phase since 2004, which is mainly categorized into Environmental Sciences and Oceanography, and the research institutions and scholars are mainly from the USA and China. The effects of human activities and climate change on the structures and functions of estuarine ecosystems are the dominant topics. Furthermore, the nature-based management solutions have been proposed to improve the functions and services of estuarine ecosystems. Currently, the habitats of estuarine wetlands worldwide have undergone varying degrees of degradation, therefore, the ecological conservation and restoration of estuarine shorelines urgently require the active participation of the public. It is highly important to integrate multi-disciplinary and multi-technology approaches to construct nature-based, more resilient, multi-service synergistic, and composite living shorelines in coastal zones. The findings of this research can provide scientific guidelines for the adaptive management and conservation of estuarine wetlands. • Research of living estuarine shorelines has developed rapidly since 2004. • China and USA stand out in this field of research. • The effects of human activities and climate change on estuary are the main topics. • Building living shorelines based on NbS is beneficial for estuarine stabilization. [ABSTRACT FROM AUTHOR]

Coastal wetlands, being a multifaceted and crucial global ecosystem, are facing significant impacts from diverse environmental alterations, particularly soil salinization. Concurrently, the escalation of extreme climate events, such as global warming, presents complex challenges for the protection and restoration efforts. Previous researches concerning microbial communities in the context of climate with continous line numbering change have predominantly concentrated on their structural aspects, with limited attention given to establishing relationships between community structure and functional attributes. In this study, a two-year investigation was conducted on conventional coastal wetland ecosystems, considering variations in salinity and seasonal temperature. Utilizing high-throughput 16S rRNA sequencing, isotope technology, and other methods to explore the bacterial community, nitrogen cycling functional groups, and nitrogen reduction process. This research aims to assess the holistic impacts of significant global environmental changes on microbial communities. The results suggest that salinity, acting as an environmental filter, has a significant impact on the microbial community composition. It leads to a decrease in species abundance, an increase in deterministic processes and the nesting of community succession, while also reducing the stability of microbial ecological networks. The mechanism by which soil salinity impacts bacterial communities involves three main aspects: direct effects, positive climate regulation, and negative regulation of soil properties. Surprisingly, soil salinity exerts a mild inhibitory influence on microbial functional genes and metabolic activity. The primary factors involved in the nitrogen reduction process include electron donors/acceptors, types of nitrogen sources, and organic carbon. The three processes are interconnected due to the impact of environmental factors and signal transmission among microbial populations. This study offers a novel scientific framework for the rehabilitation and enhancement of saline-alkali coastal ecosystems in the face of impending global changes. It achieves this by investigating the varied response patterns exhibited by microbial communities and ecological functional metabolism under salinity-induced stress. [Display omitted] • We conducted large-scale study on coastal wetland ecosystems to evaluate the different impacts of salt stress, seasonal temperature changes, and other factors on microbial communities and ecological functions. • Salt stress, as the main factor, strongly affects the microbial community in coastal wetlands and makes them unable to resist complex and drastic environmental changes, but has a weak inhibitory effect on microbial functional genes and metabolic activity. • The process of nitrogen reduction is coupled with the interaction of environmental factors and signal transmission between microbial populations, and is more influenced by electron donors/acceptors, nitrogen source types, and organic matter. [ABSTRACT FROM AUTHOR]

• The 3SV soil removal algorithm for Sentinel-2 needs further adjustment. • Different 3SV modifications are needed for red green Suaeda salsa scenes. • MTCI, MRENDVI, MND, and MNDRE best combine with 3SV. • The PSO-RFR-based semi-empirical model achieves the highest chlorophyll accuracy. In recent years, China has gradually begun restoring native salt marsh vegetation such as Suaeda salsa (S. salsa) in coastal wetlands that were damaged by the long-term invasion of Spartina alterniflora. Chlorophyll content (C ab), an important indicator of vegetation health, necessitates extensive and long-term monitoring using Sentinel-2. However, due to the influence of betacyanin (Beta), S. salsa exhibits different phenotypes (red and green) under various stress conditions, making remote sensing mechanism studies of this unique vegetation more challenging. In particular, satellite multispectral images are significantly affected by soil background in mixed pixels, making it imperative to mitigate this influence. This study explores the applicability of a recently proposed spectral separation of soil and vegetation (3SV) in Sentinel-2 multispectral and S. salsa vegetation from a remote sensing mechanism perspective, and further improves it. Additionally, a comparative analysis was conducted on the effectiveness of combining 3SV with several mainstream chlorophyll-sensitive indices. The advantages of machine learning algorithms were leveraged to develop a high-precision hybrid semi-empirical model for estimating C ab in different S. salsa phenotypes. The research findings indicate that: (1) The 3SV algorithm, adjusted with slope compensation and B2 and B4 bands, is applicable to green S. salsa scenarios. For red S. salsa scenarios, further adjustment using B2 and B3 bands and coverage fraction is required. (2) The MTCI, MRENDVI, MND, and MNDRE indices combined best with the modified 3SV, significantly reducing the RMSE of the semi-empirical models, especially under wet soil conditions with soil fraction f soil < 0.5. (3) The highest accuracy (RMSE = 3.83 μg/cm2) for C ab estimation models for different S. salsa phenotypes was achieved by combining the modified 3SV soil-removed algorithm and the four indices with particle swarm optimization random forest regression (PSO-RFR). [ABSTRACT FROM AUTHOR]

• UAV-based carbon storage estimation in the world's oldest Heritiera littoralis community. • SHAP and MGWR were coupled to explore factors affecting carbon storage variation. • XGBoost and RF is optimal in community identification and carbon storage estimation, respectively. • UAV hyperspectral imaging provides advantages in monitoring rare mangrove communities. The Heritiera littoralis , an important rare semi-mangrove species found in coastal protective forests, plays a crucial role in carbon storage and cycling within mangrove wetland ecosystems. Despite its importance, previous studies have overlooked remote monitoring of its carbon storage. Taking the world's oldest and largest natural community of H. littoralis in Shenzhen, China, as the study area, this research pioneers the use of UAV hyperspectral imaging to identify the H. littoralis community and estimate its above-ground, below-ground, and total carbon storage. The impacts of five geo-environmental factors (elevation, slope, aspect, vegetation communities, and inland distance from the coastline) on the spatial variability of carbon storage using SHapley Additive exPlanations (SHAP) and multiscale geographically weighted regression (MGWR) methods were also investigated. The results demonstrate that the first derivative bands within the red edge and near-infrared regions, the anthocyanin reflectance index 2 (ARI2) and newly-developed three-band VIs, were sensitive features for community identification and carbon storage estimation within the H. littoralis community. Among the four machine learning models (eXtreme Gradient Boosting (XGBoost), Random Forest (RF), Support Vector Machine (SVM), and Logistic Regression (LR)), the best identification accuracy for the H. littoralis community was achieved by XGBoost. Among the four machine learning models (XGBoost, RF, SVM and kernel ridge regression (KRR)), RF model achieved the best performance in estimating above-ground (R2 = 0.749, RMSE=1.723 kg/m2, EV (explained variance) = 0.704), below-ground (R2 = 0.636, RMSE=0.6 kg/m2, EV=0.606) and total carbon storage (R2 = 0.613, RMSE=2.592 kg/m2, EV=0.597). SHAP and MGWR analysis showed that elevation and inland distance from the coastline were key factors influencing the spatial variability of carbon storage. In conclusion, this study showcases significant advantages in community identification and carbon storage monitoring of rare mangrove communities, providing valuable insights for biodiversity conservation efforts and management within the H. littoralis ecosystem. [ABSTRACT FROM AUTHOR]

Coastal wetlands are extremely vulnerable to both marine damage and human activities. In order to protect these wetlands, many artificial seawalls have been constructed. However, studies are required to understand how coastal wetlands will evolve under the influence of artificial seawalls. Therefore, to understand this succession process of plants and their adaptation to habitats divided by seawalls, two different habitats inside and outside the seawalls were selected in Laizhou Bay, China. The results showed that there were 5 plant species outside the seawalls that were lower than the 13 species inside. Additionally, the dominant plant species were varied between the two habitats, with mostly annual herbs observed outside the seawalls and perennial shrubs inside. Soil salinity was higher outside the seawalls, which was the key impact factor of soil nutrient differences. The distribution of annual and perennial species may be constrained by spatial differences in soil stoichiometry. Therefore, the plants in coastal wetlands vary significantly at a small scale in response to the disturbance of artificial seawalls. The differences in soil and plants between the two habitats divided by the artificial seawalls provide a new insight for evaluating the artificial coastal projects. The only way to reduce the effects of seawalls on natural coastal wetland vegetation and ecosystem functions is to restore connectivity of tidal flow inside and outside the seawalls. • The plant species in coastal wetlands significantly varied at a small scale in response to the disturbance of artificial tidal dyke. • Soil salinity at habitat outside the dykes were higher compared to inside the dyke caused by lack of tidal input. • The distribution of annuals and perennials species might be tightly constrained by spatial differences in soil stoichiometry. [ABSTRACT FROM AUTHOR]

Nature-based coastal protection that integrates vegetated wetlands for wave attenuation and erosion mitigation shows great potential. However, there is a lack of consensus on whether longer wave periods contribute to an increase or a reduction in the attenuation of waves in vegetated wetlands, which is primarily due to the disregard of vegetation submersion states. In the current study, we modified a classic model to pinpoint the conditional role of the period. Wave attenuation by vegetation is quantified as the product of two terms: wave decay rate and time of wave group travel through a unit length. By tracing the dynamics of these two terms, the model is in good agreement with the measurements and can well explain why wave attenuation increased with longer period (from 2 to 10 s) in submerged canopies (up to 10 times) but decreased in emergent canopies (by 75%). A maximum response period (2–10 s) was found, beyond which period has no effect on wave attenuation. Furthermore, we found that in field conditions, the variation in wave period can lead to a sharp reduction in wave dissipation. which is critical for coastal safety. For instance, a 62% decrease in wave period at Galveston Island corresponded to a 40% drop in wave dissipation. This work provides a comprehensive understanding on the role of wave period in wave dissipation by wetland vegetation, which would assist in safely implementing wetlands for coastal defence. • An analytical model was modified to simulate wave dissipation by vegetation. • The role of wave period is explained by combining wave decay rate and time of wave group travel through a unit length. • Period variation may sharply reduce the storm wave attenuation capacity of marshes. [ABSTRACT FROM AUTHOR]

Altered rainfall distribution patterns resulting from climate change have substantial effects on soil carbon (C) cycling in terrestrial ecosystems particularly in water-limited regions. However, how rainfall redistribution affects soil C mineralization (CO 2 and CH 4 fluxes) in humid regions such as of the coastal saltmarshes remain unclear. We conducted mesocosm experiments in an estuarine saltmarsh in the Yellow River Delta of China, where we simulated three rainfall frequency scenarios (high-frequency, medium-frequency and low-frequency) with the same total rainfall amount in the dry and wet seasons, respectively. Soil CO 2 and CH 4 fluxes were measured before and after rain frequency treatment during a 40-day period for each season. The decrease in rainfall frequency significantly reduced the mean soil CO 2 and CH 4 fluxes during the dry season, but had no effect on either flux during the wet season. The seasonal variation in the response of soil C mineralization to rainfall frequency changes could be explained by the changes in antecedent soil water and salinity conditions, soil C substrate, microbial activities and diversity. Thus, the effects of changes in rainfall frequency on soil C mineralization are regulated by season, and should be considered when predicting the future C balance of coastal wetland ecosystems. Furthermore, the shift in precipitation frequency distribution towards increasing heavy rainfall events during the dry season in this region will have a great effect on soil C losses, potentially feeding back into the soil C budget and stability in this estuarine saltmarsh. • Response of soil C mineralization losses to rainfall frequency is season-dependent. • Decrease in rainfall frequency reduced soil CO 2 and CH 4 fluxes during dry season. • Rainfall frequency had no effect on mean values of both fluxes during wet season. • Soil moisture fluctuation and salinity explain variations in soil C loss response. [ABSTRACT FROM AUTHOR]

Wetlands are widely regarded as biogeochemical hotspots of mercury methylation but little is known regarding such roles of mangrove forests. Here, we examined the detailed depth profile of mercury, methylmercury, and organic matter in surface sediments within an estuarine pond at Mai Po Nature Reserve in Hong Kong, China. There is a progressive enrichment of organic matter in sites closer to mangrove forests, and methylmercury showed a significantly positive correlation with organic matter content (p < 0.001). Methylmercury in sediments is significantly (p < 0.05) higher in the summertime when the temperature is elevated but salinity is reduced. Further, sediments at or near the mangrove forest have lower carbon to nitrogen ratio, which may imply more labile organic matter in these organic-rich sediments that can promote microbial mercury methylation. In summary, mangrove forests can enhance net methylmercury production and increase the risk to the migratory birds overwintering in this internationally important wetland. [Display omitted] • Toxic methylmercury levels in a subtropical coastal wetland are correlated with organic matter content in sediments. • Mangrove forests can enhance the overall methylmercury production in coastal wetland ecosystems. • Increasing temperature and decrease salinity can enhance methylmercury production in sediments. [ABSTRACT FROM AUTHOR]

Denitrification, anammox, and DNRA are three important nitrogen (N) reduction pathways in estuarine sediments. Although salinity is an important variables controlling microbial growth and activities, knowledge about the effects of changing salinity on those three processes in estuarine and coastal wetland sediments are not well understood. Herein, we performed a 60-d microcosms experiment with different salinities (0, 5, 15, 25 and 35 ‰) to explore the vital role of salinity in controlling N-loss and N retention in estuarine wetland sediments. The results showed that sediment organic matter, sulfide, and nitrate (NO 3 −) were profoundly decreased with increasing salinity, while sediment ammonium (NH 4 +) and ferrous (Fe2+) varied in reverse patterns. Meanwhile, N-loss and N retention rates and associated gene abundances were differentially inhibited with increasing salinity, while the contributions of denitrification, anammox, and DNRA to total nitrate reduction were apparently unaffected. Moreover, denitrification rate was the most sensitive to salinity, and then followed by DNRA, while anammox was the weakest among these three processes. In other words, anammox bacteria showed a wide range of salinity tolerance, while both denitrification and DNRA reflected a relatively limited dynamic range of it. Our findings could provide insights into temporal interactive effects of salinity on sediment physico-chemical properties, N reduction rates and associated gene abundances. Our findings can improve understanding of the effects of saltwater incursion on the N fate and N balance in estuarine and coastal sediments. • Salinity plays a key role in regulating the nitrate reduction processes. • N-loss rates and N retention were both inhibited with increasing salinity. • Denitrification bacteria activity was the most sensitive to salinity. • Anammox bacteria activity showed a wide range of salinity tolerance. [ABSTRACT FROM AUTHOR]

The microorganism in rhizosphere systems has the potential to regulate the migration of arsenic (As) in coastal tidal flat wetlands. This study investigates the microbial community in the iron plaque and rhizosphere soils of Spartina alterniflora (S. alterniflora) and Suaeda salsa (S. salsa), as two common coastal tidal flat wetland plants in China, and determines the impact of the As and Fe redox bacteria on As mobility using field sampling and 16S rDNA high-throughput sequencing. The results indicated that As bound to crystalline Fe in the Fe plaque of S. salsa in high tidal flat. In the Fe plaque, there was a decrease in the presence of Fe redox bacteria, while the presence of As redox bacteria increased. Thus, the formation of Fe plaque proved advantageous in promoting the growth of As redox bacteria, thereby aiding in the mobility of As from rhizosphere soils to the Fe plaque. As content in the Fe plaque and rhizosphere soils of S. alterniflora was found to be higher than that of S. salsa. In the Fe plaque, As/Fe-reducing bacteria in S. alterniflora , and As/Fe-oxidizing bacteria in S. salsa significantly affected the distribution of As in rhizosphere systems. S. alterniflora has the potential to be utilized for wetland remediation purposes. [Display omitted] • As bound to crystalline Fe was the major As form in the Fe plaque of S. salsa. • As content in Fe plaque and rhizosphere soils of S. alterniflora was higher. • Fe plaque formation promoted the enrichment of As redox bacteria. • Bacillus, Desulfuromonas, and Halomonas played a predominant role in As behavior. [ABSTRACT FROM AUTHOR]

• This study developed a multi-feature decision approach for extraction of tidal flats based on the Landsat time series and GEE platform. • The spatial-temporal distribution of tidal flats in Zhoushan Archipelago, China is mapped. • The spatio-temporal characteristics of tidal flats in Zhoushan Archipelago, China are analyzed from 1985 to 2020. Tidal flats serve as vital spatial resources within coastal wetlands and play crucial roles in biological habitat preservation, environmental conservation, and human development. However, accurately delineating their extent from instantaneous remote sensing images poses challenges, owing to the dynamic interplay between seawater and land. Therefore, this study utilized the consistency of remote sensing satellites and developed a multi-feature decision approach based on the long-term remote sensing datasets and the Google Earth Engine (GEE) cloud platform for determining the spatial extent, classifying types, and mapping the spatial-temporal distribution of the tidal flats. Initially, a multi-temporal image stack was compiled from the filtered remote sensing images. Subsequently, the modified normalized difference water index (MNDWI) and automated water extraction index (AWEI) were calculated to establish the maximum and minimum water surfaces using the extreme value composite algorithm (EVCA). The Otsu algorithm and spatial overlay analysis method were then utilized to accurately delineate the spatial extent of the tidal flats. Additionally, the Normalized Difference Vegetation Index (NDVI) was utilized to accurately identify tidal flat types. Post-processing involves elevation data and mathematical morphological methods to mitigate the impact of permanent water bodies. Finally, the accuracy of the extracted spatial extent and types of tidal flats was evaluated. The efficacy and practicality of the proposed method were validated using the Zhoushan Archipelago and Landsat time series in China. The results revealed the following: (1) the acquired tidal flat information exhibited evident boundaries and accurate types, achieving an overall accuracy (OA) of 94.80 % and a Kappa coefficient of 0.89; (2) the area of tidal flats in the Zhoushan Archipelago increased from 2,182.19 ha in 1985 to 3,761.21 ha in 2020, with an average annual increase of 45.12 ha and an average annual increase rate of 1.57 %; and (3) over 35 periods, the area transformed from other land types to tidal flats amounted to 2,895.74 ha, while the area converted from tidal flats to other land types totaled 1,651.90 ha. The three islands with the most rapid growth in tidal flat area were Liuheng Island, Dachangtu Island, and Daishan Island, with changes of 675.68 ha, 380.47 ha, and 362.63 ha, respectively. This method can offer an automated, swift, and accurate approach for tidal flat extraction, demonstrating high precision and practical effectiveness, thereby providing robust technical support for coastal resource surveys. [ABSTRACT FROM AUTHOR]

Wetlands are crucial ecosystems that are increasingly threatened by anthropogenic activities. L'Albufera Natural Park, the second-largest coastal wetland in Spain, faces significant pressures from surrounding agricultural lands, industrial activities, human settlements, and associated infrastructures, including treated wastewater inputs. This study aimed at (i) establishing pathways of emerging pollutants entering the natural wetland using both target and non-target screening (NTS) for management purposes, (ii) distinguishing specific contamination hotspots through Geographic Information System (GIS) and (iii) performing basic ecological risk assessment to evaluate ecosystem health. Two sampling campaigns were conducted in the spring and summer of 2019, coinciding with the start and end of the rice cultivation season, the region's primary agricultural activity. Each campaign involved the collection of 51 samples. High-resolution mass spectrometry (HRMS) was employed, using a simultaneous NTS approach with optimized gradients for pesticides and moderately polar compounds, along with complementary NTS methods for polar compounds, to identify additional contaminants of emerging concern (CECs). Quantitative analysis revealed that fungicides comprised a substantial portion of detected CECs, constituting approximately 50% of the total quantified pesticides. Tebuconazole emerged as the predominant fungicide, with the highest mean concentration (>16.9 μg L−1), followed by azoxystrobin and tricyclazole. NTS tentatively identified 16 pesticides, 43 pharmaceuticals and personal care products (PPCPs), 24 industrial compounds, and 12 other CECs with high confidence levels. Spatial distribution analysis demonstrated significant contamination predominantly in the southwestern region of the park, gradually diminishing towards the north-eastern outlet. The composition of contaminants varied between water and sediment samples, with pharmaceuticals predominating in water and industrial compounds in sediments. Risk assessment, evaluated through risk quotient calculations based on parent compound concentrations, revealed a decreasing trend towards the outlet, suggesting wetland degradation capacity. However, significant risk levels persist throughout much of the Natural Park, highlighting the urgent need for mitigation measures to safeguard the integrity of this vital ecosystem. [Display omitted] • L'Albufera Natural Park is polluted by more than 159 synthetic organic substances. • Fungicides are the key pollutants in water and sediments both by target analysis and NTS. • Pharmaceuticals in water and industrial products in sediments are the other major pollutants by NTS. • Assessment only of target compounds showed important ecological risk. [ABSTRACT FROM AUTHOR]

Glyphosate is a globally dominant herbicide. Here, we studied the degradation and microbial response to glyphosate application in a wetland soil in central Delaware for controlling invasive species (Phragmites australis). We applied a two-step solid-phase extraction method using molecularly imprinted polymers designed for the separation and enrichment of glyphosate and aminomethylphosphonic acid (AMPA) from soils before their analysis by ultra-high-performance liquid chromatography (UHPLC) and Q Exactive Orbitrap mass spectrometry methods. Our results showed that approximately 90 % of glyphosate degraded over 100 d after application, with AMPA being a minor (<10 %) product. Analysis of glyphosate-specific microbial genes to identify microbial response and function revealed that the expression of the phn J gene, which codes C-P lyase enzyme, was consistently dominant over the gox gene, which codes glyphosate oxidoreductase enzyme, after glyphosate application. Both gene and concentration data independently suggested that C-P bond cleavage—which forms sarcosine or glycine—was the dominant degradation pathway. This is significant because AMPA, a more toxic product, is reported to be the preferred pathway of glyphosate degradation in other soil and natural environments. The degradation through a safer pathway is encouraging for minimizing the detrimental impacts of glyphosate on the environment. [Display omitted] • Identified the occurrence of benign degradation pathways of glyphosate in soils. • Expression of the phnJ gene confirmed the dominance of C-P bond cleavage. • Suppressing AMPA production is most favored for protecting the environment. [ABSTRACT FROM AUTHOR]

Based on integrated geochemical, mineralogical and stratigraphic-sedimentological analyses of core section KB 4507/1001 Essen-Bedingrade from the Münsterland Cretaceous Basin (northern Germany), the geochemical and depositional environment of a Late Cretaceous greensand giant has been elucidated. The >100-m-thick Cretaceous succession comprises the Essen Greensand (Cenomanian), Büren (lower Turonian), Duisburg (middle Turonian to lower Coniacian) and Emscher formations (middle to upper Coniacian), essentially consisting of alternating greensand and marl lithofacies. X-ray diffraction analyses showed that the abundant green grains undoubtedly constitute glauconitic minerals with high-order, 1M-type layer stacking. The depositional environment can be characterized as a shallow-marine setting in which nearshore greensands interfingered with mid-shelf marls. Inorganic geochemical analyses normalized to Al and compared to average shale (AS) show that most element/Al (E/Al) ratios are higher than AS values, including the chemical index of alteration (CIX). This suggest that an intensely chemically weathered wet hinterland provided for a constant supply of essential elements required for nearshore glaucony authigenesis under variably reducing or oxidizing conditions and slightly increased palaeoproductivity. The leaching of paleosols and swamp-like coastal wetlands during transgressive phases related to eustatic early Late Cretaceous sea-level changes was an important source for trace metals and nutrients while the considerable influx of terrestrial organic matter suggests a significant input of K related to plant decay. In a nutshell, our new integrated data from the Münsterland Cretaceous Basin provide important novel insights into the formative processes of authigenic glauconitic minerals during warm-humid climate phases of Earth history. • An Upper Cretaceous greensand giant has been studied with an integrated approach. • XRD analyses proved glauconitic minerals with high-order, 1M-type layer stacking. • Bulk-rock element/Al ratios and CIX are mostly higher than average shale values. • Geochemical data proved an intensely chemically weathered, leached hinterland. • Fluvial input yielded crucial elements required for nearshore glaucony formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • ARGs abundance and diversity increased after coastal wetland conversion. • Large numbers of ARGs were shared among different land uses. • Land use conversion to upland increase ARG risk. • The distribution of ARGs was largely affected by bacteria but not MGEs. Land use conversion in estuary wetlands may affect the transmission of antibiotic resistance genes (ARGs), while the risk rank of the ARGs and the change of clinically relevant ARGs under various land-use types are not well understood. This study used metagenomics to reveal the diversity and abundance of ARGs across five distinct land uses: reed wetland, tidal flat, grassland, agricultural land and fallow land, as well as their distribution and potential health risks. Results showed that high numbers of ARG subtypes and classes were detected irrespective of land-use types, notably higher in agricultural land (144 ARG subtypes). The most shared ARG subtypes were multidrug resistance genes across all the land uses (29 subtypes, 4.7 × 10−2-1.5 × 10−1 copies per 16S rRNA gene copy). Proteobacteria and Actinobacteria were primary ARG hosts, with 18 and 15 ARGs were found in both of them, respectively. The ARG subtype mdtB was the most dominant clinical ARG detected with 90 % amino acid identity. The change of ARGs exhibited a consistent trend across land uses in terms of health risk ranks, with the highest observed in fallow land and the lowest in reed wetland. This study reveals the distribution pattern of ARGs across various land-use types, and enhances our understanding of the potential health risks associated with ARGs in the context of coastal wetland conversion in estuary areas. [ABSTRACT FROM AUTHOR]

[Display omitted] • A VI-integrated RF classifier enhances the LULC classification accuracy of >95 %. • EVI verifies its robustness in distinguishing between sparse and dense mangroves. • Changes in sparse and dense mangroves indicate the effects of disturbances. • Aquacultural land affects land cover outside the mangrove. • Accurate detection of mangroves promotes restoration and conservation measures. The coastal wetlands represented by mangroves are vulnerable to disturbances. To clarify the effects of disturbances quantitatively on mangroves, spatiotemporal changes in land use and land cover (LULC) were compared between the inside and outside of mangroves during 1988 and 2020 in Bangladesh by remote sensing. The mangrove region, which had diverse surface greenness due to natural and anthropogenic disturbances, were surveyed. Changes in greenness were estimated by five vegetation indices (VIs). To increase in the accuracy of land use classification, the five VIs were combined under a random forest (RF) classifier. The five VIs were: normalized difference vegetation index (NDVI), green NDVI (GNDVI), soil-adjusted VI (SAVI), green–red VI (GRVI) and enhanced VI (EVI), using data obtained from Landsat TM (30 m resolution) and Sentinel-2A (10 m) via Google Earth Engine. A Moran's I analysis showed a random pattern of training samples of LULC classes for integrated RF classification. The classification accuracy was evaluated using the reference point data with multiple comparisons of VIs and κ coefficient. The area was classified into eight LULC classes. Although the respective VIs depicted unique characteristics, the accuracies of them were less than 89 %. The integrated classifier improved the accuracy of 96–97 % with κ of 0.96 in 1988 and 0.97 in 2020. The VI-integrated RF was the most effective classifier for LULC, particularly for separating mangroves from homestead vegetation. The changes for 32 years showed that the dense mangrove occupied 42 % of surveyed area in 1988 but declined ca 622 km2 in 2020, whereas sparse mangrove and aquaculture increased by 487 km2 and 464 km2, respectively, out of the total area of 8,360 km2. The changes in LULC classes were mostly from dense mangroves to sparse mangroves, sparse mangroves to dense mangroves and from cropland to bare land and aquaculture. Inaccessible mangrove degradation should result from natural disturbances, i.e., tropical cyclones, while areas near forest boundaries were distorted by anthropogenic disturbances such as aquaculture development. The restoration of habitat quality, mangrove afforestation and sustainable aquaculture practices were effective indicators for improving the mangrove ecosystems. Since natural and anthropogenic disturbances induce substantial loss of mangrove vegetation, the VI-integrated RF classifier should be applied for monitoring LULC and for developing the sustainable management strategies. [ABSTRACT FROM AUTHOR]

Human activities including urbanization, construction of coastal infrastructure, and sand extraction, have altered the natural coastal dynamics. Joao Pessoa's coastline is also influenced by sea level rise and climatic variations, contributing to its geomorphic changes. Numerous natural hazards like cyclonic, erosional activities, and other moments happened in the region like Joao Pessoa from Brazil between 2000 and 2011. A comprehensive examination of several spatial data sources, such as the topographical map of the Geological Survey of Brazil, the Landsat 8–9 OLI/TIRS (30 m) image, the SRTM dataset, and the ASTER DEM dataset was carried out. Volumetric changes in coastal landforms between 2000 and 2011 were assessed using change detection techniques such as cross-shore profile analysis, topographical change detection, and geomorphic change detection using DEM of Difference (DoD). According to their evolutionary processes, the coastal landform features are mostly covered by the Younger Deltaic Plain (307.76 Sq.km) and Younger Coastal Plain (259 Sq.km). The topographical change research indicates that the beach landforms have fallen in elevation by −23 to 123 m from SRTM and −15 to 187 m from ASTER DEM. 8 profiles in all were polled for the assessment of topographical change. The volumetric change in sediment load calculated by the DoD model between 2000 and 2011 exhibits both an area loss of −60 to −1 m along the north portion of the study area and a gain of 1–92 m accretion towards the south region. In the Joao Pessoa coastal region, the overall volumetric study indicates that landform erosion is 388.22 m3km, while landform accretion is 853.78 m3km. Coastal managers will find the study valuable as it contributes to a database on coast vulnerability and provides insights into the decadal shift in coastal environments. • Analysis of Volumetric and Geomorphological changes mapping using Remote Sensing and GIS approaches. • Coastal landform changes respect to sea level rise and natural hazards. • DEM of Difference (DoD) analysis using Remote sensing techniques. [ABSTRACT FROM AUTHOR]

Severely degraded coastal salt marshes with impaired ecological functions urgently need to be restored to improve blue carbon sequestration. Although plant residues and biochar have been used to restore degraded wetlands, the dose-effects of these plant additives on soil organic carbon fractions in degraded coastal wetlands are still unclear. Here, we investigated the dynamic changes in DOC components and mineral-associated organic carbon, such as calcium-bound organic carbon (Ca-OC) and iron/aluminum-bound organic carbon (Fe/Al-OC), in a degraded coastal salt marsh in a 60-day incubation experiment with low (0.1%), medium (1%), and high (3%) doses of Phragmites australis straw (PS) and Phragmites australis -derived biochar (PB) addition treatments. The results showed that the medium and high doses of PB additives increased humus-like substances, with the maximum proportion occurring on day 60 of the incubation. The fluorescence index (FI) and biological index (BIX) were >1.9 and 0.8, respectively, and the humification index (HIX) was < 4 in most treatment groups. The mineral-associated organic carbon (Ca-OC and Fe/Al-OC) contents were higher in the 1% PS and 3% PS treatments (p < 0.05). The PS additives increased the soil Ca-OC/SOC and Fe/Al-OC/SOC ratios, whereas the PB additives decreased them. This study demonstrated that PS and PB are potential carbon-rich additives for enhancing soil organic carbon stability and carbon sequestration in coastal wetland restoration projects, contributing to regional carbon neutrality. • Carbon-rich additives regulated soil organic carbon fractions in salt marshes. • Phragmites australis straw increased soil mineral-associated organic carbon. • Carbon-rich additives improved soil humification degree and mineral protection. [ABSTRACT FROM AUTHOR]

Sediment deposition in coastal wetlands is key to maintaining marsh elevation during periods of sea level rise. Deposition occurs naturally during storms to increase marsh elevation or when dredged sediments are intentionally introduced during restoration to build elevation capital. The deposition of sediments containing iron sulfide compounds (FeS and FeS 2) under natural or managed scenarios alters biogeochemical cycles, including the potential to induce dramatic declines in soil pH under prolonged oxidizing conditions. This 20-week mesocosm study investigated FeS and FeS 2 dynamics under continuously flooded, tidal, and drought treatments following a simulated natural or restoration deposition event by placing hyposulfidic sediment onto the marsh soil surface. The introduced FeS and FeS 2 rapidly oxidized (< 21 days) after sediment deposition across all treatments, followed by declining oxidation reduction potentials, increasing dissolved Fe concentrations, and subsequent FeS and FeS 2 re-precipitation in flooded and tidal treatments. Nominal pH declines occurred in flooded and tidal treatments due to re-precipitation of FeS and FeS 2 minerals. Conversely, pH decreased 1–2 units under simulated drought conditions. Observational and modeling results indicate that S−2 generation limited the rate of FeS and FeS 2 formation following sediment deposition in alignment with previous field studies. Results suggest that the deposition of hyposulfidic sediments during storms and restoration events pose minimal risk of acidification when prolonged saturated conditions are present. However, short term FeS and FeS 2 oxidation and re-precipitation likely occur following both natural (over wash) and managed (restoration) scenarios as the deposited sediments achieve new dynamic biogeochemical equilibria. Coastal resource managers can use these results to ensure restoration projects maximize positive restoration outcomes while minimizing the risk of soil acidification through the informed management of FeS and FeS 2 minerals. • Hyposulfidic sediment deposition induced wetland soil biogeochemical changes, including pH change under simulated drought • Iron sulfide compounds oxidized when deposited, then re-precipitated under saturated conditions • Hyposulfidic sediment deposition poses low acidification risk under saturated conditions • Soil morphology provided a useful proxy measure of sediment Fe & S biogeochemistry • Results inform wetland management following storm driven deposition and deliberate sediment introduction during restoration [ABSTRACT FROM AUTHOR]

Coastal wetlands are significant sources of nitrous oxide (N 2 O), a potent greenhouse gas and ozone depleting agent. Land reclamation is known to change N 2 O emissions from coastal wetlands, but the long-term impacts on N 2 O sources and emissions are not well-understood. Here, we performed respiration inhibition and molecular techniques to dissect the long-term effects of coastal reclamation on bacterial, fungal and overall N 2 O emissions across a 53-year chronosequence of paddy soils reclaimed from coastal wetlands. Our findings showed that reclamation of coastal wetlands to paddy soils generally promoted N 2 O emissions in the chronosequences, despite a significant reduction in uncultivated paddy soils. The observed increase in N 2 O emissions was primarily attributed to an imbalance between N 2 O production and consumption driven by bacterial denitrifiers. Additionally, reclamation of coastal wetlands to paddy soils shifted N 2 O emissions from fungal to bacterial predominance in the chronosequences, with denitrification mediated by bacterial denitrifiers dominating bacterial N 2 O emissions. By integrating the analysis of N 2 O emission rates with soil physicochemical and microbiological properties, we demonstrated that the reduced salinity following coastal reclamation diminished the relative abundance of key fungal denitrifiers (e.g., Paraconiothyrium, Penicillium and Trichoderma), thus lowering the fungal contribution to N 2 O emissions. This study provides novel insights into the long-term influences of coastal reclamation on the sources and emissions of N 2 O, and enhance our knowledge of the underlying mechanisms driving these impacts, thereby contributing to improving future models of N 2 O emissions from coastal ecosystems under global change. [Display omitted] • Long-term impacts of coastal reclamation on N 2 O source and emission were explored. • Influences of coastal reclamation on N 2 O emission depend on reclamation types. • Coastal reclamation shifted N 2 O emission from fungal to bacterial dominance. • Bacterial denitrifiers mediated denitrification dominated bacterial N 2 O emission. • Reduction in the abundance of key fungal denitrifiers led to shift in N 2 O source. [ABSTRACT FROM AUTHOR]

To elucidate the spatial-temporal impact of invasive saltmarsh plant Spartina anglica on the biogeochemical processes in coastal wetlands, we investigated the rates and partitioning of organic carbon (C org) mineralization in three representative benthic habitats: (1) vegetated sediments inhabited by invasive S. anglica (SA); vegetated sediments by indigenous Suaeda japonica ; and (3) unvegetated mud flats. Microbial metabolic rates were greatly stimulated at the SA site during the active growing seasons of Spartina , indicating that a substantial amount of organic substrates was supplied from the high below-ground biomass of Spartina. At the SA site, sulfate reduction dominated the C org mineralization pathways during the plant growing season, whereas iron reduction dominated during the non-growing season. Overall, due to its greater biomass and longer growing season than native Suaeda , the expansion of invasive Spartina is likely to greatly alter the C org -Fe-S cycles and carbon storage capacity in the coastal wetlands. [Display omitted] • Invasive Spartina anglica enhanced microbial metabolic activity in coastal wetlands. • Labile organic substrates from the Spartina stimulated microbial activity. • Dense root systems of the Spartina remarkably enhanced iron cycling. • Spartina altered the C-Fe-S cycle while stimulating organic carbon mineralization. • Invasion of Spartina likely increases the carbon storage capacity of coastal sediment. [ABSTRACT FROM AUTHOR]

Clarifying the interaction between aboveground plant communities and soil seed banks is conducive to predicting community potential regeneration direction. However, the spatial structure of invasive clonal plants should be reasonably quantified. We assumed that the selection effect of Spartina alterniflora community spatial structure on soil seed bank species composition would affect the seed reproduction invasion intensity. Taking the native species of Phragmites australis in Dongtan wetland as a reference, we explored the nitrogen regulation on the soil seed bank formation process after S. alterniflora became the dominant species. The results showed that S. alterniflora growth tended to be stable in summer and autumn, and its height change trend and peak height under different coverage were relatively consistent. The seasonal variation of P. australis height was opposite to that of S. alterniflora. At community mature stage in the autumn, the dominance index of S. alterniflora and P. australis showed a downward trend from low to high aboveground coverage after the soil seed bank germination, and the dominance index of S. alterniflora was higher than that of P. australis. The overlapping resistance structure of S. alterniflora community was synergistically affected by soil ammonium nitrogen, leaf total nitrogen and soil microbial biomass nitrogen, and the effect of structure on the soil seed bank formation under different soil depth showed an opposite trend. Our results suggested that the overlapping complementarity between S. alterniflora would play a positive regulatory role between functional trait plasticity and sexual reproduction advantage. [ABSTRACT FROM AUTHOR]

Governance plays an important role in coastal wetland protection and restoration. Through a review of the literature on the governance of coastal wetlands, we assessed the drivers influencing the governance of coastal wetlands. We found 66 cases addressing seven governance themes: politics, institutions, land tenure, economy, policies, resources, and behavior. The literature was dominated by studies focused on the protection of mangrove areas in lower-middle-income countries and at the local scale. We found 61 drivers that influence the governance of coastal wetlands. The literature highlighted the participation of local communities as a critical driver of protection and restoration practices and identified a range of challenges. Local communities' participation in governance depends on the implementation of multilevel, decentralized, and integrated practices that promote equitable distribution of power between actors. Solutions to enhance local community rights and land tenure, compensation for alternative livelihoods, and unequal power dynamics are significant knowledge gaps that need to be addressed in future research. • The governance literature focuses on mangrove protection. • Most studies are from lower-middle-income countries, at local scales. • Participation of local communities forms the central narrative. • Decentralized, integrated, multilevel practices could improve governance of wetlands. [ABSTRACT FROM AUTHOR]

Coastal wetlands have the capacity to trap and store large amounts of carbon and function as efficient blue carbon sinks—an essential nature-based approach for climate change mitigation. Owing to anthropogenic activities and sea level rise (SLR), coastal wetlands located at the land–sea interface are subject to severe deterioration, transformation, and loss. Assessing coastal wetland vulnerability to SLR serves as the foundation for developing climate change adaptation solutions and is critical for maintaining the stability and sustainability of coastal ecosystems. In this paper, we provide an overview of approaches for assessing coastal wetland vulnerability and find the following: (1) The Rod Surface Elevation Table–Marker Horizon (RSET–MH) method can provide accurate and repeatable measurements of local surface elevation changes; however, contrary to Relative Sea Level Rise (RSLR) recorded by long-term tide gauges, RSETs recording the current surface elevation changes of coastal wetlands provide short-period monitoring with uneven coverage. Hence, RSET monitoring needs to be further extended to obtain long-term broad-coverage data for more accurately assessing coastal wetland vulnerability. (2) Existing vertical accretion models for coastal wetlands account for important feedback mechanisms between SLR and sediment accretion; however, they do not account for the relationship between vertical accretion and climate change, i.e., elevated atmospheric carbon dioxide concentration. This omission may lead to a shift in the SLR threshold for the survival of coastal wetlands. (3) Human activities affect the stability of wetlands, and current studies on coastal wetland vulnerability do not consider the potential impacts of human activities on these areas, resulting in an incomplete assessment of wetland risk. Incorporating the effects of human activities into biophysical models of coastal wetland evolution is a major challenge that must be addressed. [ABSTRACT FROM AUTHOR]

Accelerating climate change from the thermal expansion of oceans and losses from terrestrial glaciers and ice sheets causes sea level rise (SLR), damaging coastal ecosystems and generating non-market value losses. Using an innovative Artificial Intelligence (AI) projection method and 18 existing geographical SLR projections, we project future sea level rise and storm surge (SLR/S) for the 1600 km coastline of the Kimberley Region, Western Australia, a region with a larger surface area than Great Britain, Ireland, and Portugal combined and with a permanent population of 40,000 people of which more than 16,000 identify as Indigenous. Using our projected coastal area inundation from future SLR, we estimated the non-market value losses of the Kimberley's coastal ecosystem and wetlands with projected SLR/S to 2050 and 2100 for Representative Concentration Pathway (RCPs) 4.5 and 8.5. Average annual non-market losses from SLR/S in 2050 and 2100 in the Kimberley are large relative to the size of the regional economy and are estimated to range from A$2.7 to A$4.3 billion (2050) and A$8.1 to A$15.8 billion (2100), depending on the RCP and temperature pathway. Our findings highlight the need for adequately resourced community-based approaches to climate adaptation. [ABSTRACT FROM AUTHOR]

The Philippines has rich mangrove biodiversity, yet synthesis of existing knowledge and conservation caveats relevant to developing critical priorities remains deficient. Here, we aimed to identify knowledge shortfalls and conservation challenges, and recommend future research priorities to advance mangrove conservation in this country. We examined research trends and priorities for the mangroves in the Philippines. We also analyzed the species and spatial trends of research from 2000 to 2023 using the Species Research Effort Allocation (SREA) index. Over two decades, four taxa (viz., Rhizophora apiculata, R. mucronata, Sonneratia alba, and Avicennia marina) have dominated mangrove-related research in the Philippines. In contrast, other species, such as Kandelia candel and R. × lamarckii received minimal attention. We found an increasing trend in mangrove research in the Philippines; however, crucial information on the biology of the mangroves remains unclear and requires careful consideration. Our spatial analysis revealed variations in mangrove species richness across the country and disproportional species research efforts between geographical areas within the country. The disparities in research efforts across species and areas, and the decline in mangrove populations emphasize the need for a comprehensive and prioritized approach. The knowledge gaps and conservation challenges for Philippine mangroves highlighted in our synthesis provide valuable insights into the importance of developing targeted solutions to address them. Our study stresses the need for innovative conservation strategies, appropriate species selection for rehabilitation, and enhanced collaboration and data sharing among research institutions to ensure sustainability and conservation of vital mangrove ecosystems in the Philippines. • Research effort remains limited across species and coastal areas in the Philippines. • Studies on species ecology and environmental responses are needed. • Extent of threats for mangroves needs more understanding. • Mangrove ecosystem services require more mainstreaming. • Equitable partnership among institutions is important to conserve mangrove species in the Philippines. [ABSTRACT FROM AUTHOR]

Wetlands provide numerous ecosystem services essential for biodiversity conservation, climate change mitigation, and human well-being. Nevertheless, there are still no complete and uniform wetland maps providing information on the location, distribution, size, and changing status of wetlands in Africa. In this study, we used 130,000 Landsat satellite images and 270,000 sampling points evenly distributed across Africa to classify wetlands with a random forest classifier based on the Google Earth Engine (GEE) cloud platform. This resulted in the first systematic and comprehensive map of existing wetlands in Africa that quantified the area and distribution of these wetlands at a spatial resolution of 30 m, with an overall wetland producer accuracy of 90.22 % and user accuracy of 95.74 %. To address the seasonal variation in African wetlands, we used a dynamic threshold segmentation method based on the Otsu method, which can extract the extent of wetlands under different periods more accurately based on Landsat time series and African phenology data. Our results show that the total African existing wetlands extent from 2019 to 2021 (here in 2020), was approximately 1,341,500 km2, excluding shallow marine waters, comprises 3.98 % of Africa's total land area. Of these wetlands, inland wetlands account for 81 %, and coastal wetlands account for 19 %. The wetlands in Africa were symmetrically distributed around the equator and decreased with increasing latitude, accounting for 97 % of the total wetland area being within the 20°N and 20°S latitudes. African marshes were highly dynamic, expanding by 92.22 % from the dry to wet season. Our study demonstrates the substantial potential of large data samples, multiple wetland classification features (spectral-temporal, topographic, and hydrological features), and random forest classification in GEE for large-scale wetland mapping. The resulting wetland maps provide new baseline data for large-scale monitoring of seasonal dynamics and long-term trends in African wetlands. [ABSTRACT FROM AUTHOR]

Coastal wetlands of the Laurentian Great Lakes are diverse and productive ecosystems that provide many ecosystem services, but are threatened by anthropogenic factors, including nutrient input, land-use change, invasive species, and climate change. In this study, we examined one component of wetland ecosystem structure – phytoplankton biomass – using the proxy metric of water column chlorophyll- a measured in 514 coastal wetlands across all five Great Lakes as part of the Great Lakes Coastal Wetland Monitoring Program. Mean chlorophyll- a concentrations increased from north-to-south from Lake Superior to Lake Erie, but concentrations varied among sites within lakes. To predict chlorophyll- a concentrations, we developed two random forest models for each lake – one using variables that may directly relate to phytoplankton biomass ("proximate" variables; e.g., dissolved nutrients, temperature, pH) and another using variables with potentially indirect effects on phytoplankton growth ("distal" variables; e.g., land use, fetch). Proximate and distal variable models explained 16–43% and 19–48% of variation in chlorophyll- a , respectively, with models developed for lakes Erie and Michigan having the highest amount of explanatory power and models developed for lakes Ontario, Superior, and Huron having the lowest. Land-use variables were important distal predictors of chlorophyll- a concentrations across all lakes. We found multiple proximate predictors of chlorophyll- a , but there was little consistency among lakes, suggesting that, while chlorophyll- a may be broadly influenced by distal factors such as land use, individual lakes and wetlands have unique characteristics that affect chlorophyll- a concentrations. Our results highlight the importance of responsible land-use planning and watershed-level management for protecting coastal wetlands. [ABSTRACT FROM AUTHOR]

The four typical wetlands of Phragmites australis wetland (TPa), Tamarix chinensis wetland (Tc), Suaeda salsa wetland (Ss) and Spartina alterniflora wetland (Sa) in the Yellow River Delta were selected to clarify the spatial heterogeneity of soil nutrients and their ecological stoichiometric characteristics under fiddler crab activities. The results showed that soil particle size, soil salinity and pH in Tc, TPa and Ss were greatly changed by fiddler crab activities. The averaged contents of TOC and TN in wetlands with fiddler crab activities (FC) were higher than those in wetlands without fiddler crab activities (CK). The averaged NH 4 +-N contents of FC group in Tc, Ss and Sa were 93.42%, 52.14% and 20.05% higher than those of CK group (p <0.05), respectively. The averaged NO 3 −-N contents of Tc and Sa in FC group were 89.79% and 167.70% higher than those of CK group (p <0.01), respectively. The variation tendency of C/N and C/P in four wetland types were greatly similar with the TOC, and N/P was similar with TN. Multi-ANOVA results showed that soil carbon and nitrogen were significantly influenced by fiddler crab activities and wetland types (p <0.05). The PCA and RDA analysis results indicated that the bioturbation from fiddler crab made the influencing factors of nutrient elements diversified. The fiddler crab activities were favorable to the soil nutrients accumulation and could reduce the nitrogen limitation of coastal ecosystem. Our results should be of importance to insight the biogeochemical process of soil nutrient elements differentiation by fiddler crab activities in coastal wetlands. [ABSTRACT FROM AUTHOR]

Here we present findings from a natural experiment to better understand coastal wetland plant community responses to rising water levels. Plant communities were monitored in three vegetation zones (submergent, emergent, and wet meadow) at Allouez Bay, a lacustrine coastal marsh, six times over years 2011–2020. Lake Superior water levels reached record-highs in 2017, and again in 2019. During our six sampling campaigns, we encountered eighty-four vascular plant species, seven of which were non-native. Except for reductions in total plant cover in the wet meadow zone, emergent and wet meadow plant communities were only marginally affected by rising water. Percent cover of non-native species did not increase in a clear pattern. Temporal changes in floristic quality were non-significant at the whole site level, and mean coefficient of conservatism values ranged from 5.3 to 6.0. Aquatic vegetation in the submergent zone was most affected by rising water. Submergent zone richness declined from sixteen plant species in 2011 to zero in 2020. Multivariate PERMANOVA analysis showed significant effects of year on site-wide plant composition. Temporal composition changes were predominately driven by species turnover in the submergent vegetation zone, whereby floating aquatic species were replaced by non-floating species from 2011 to 2017, and an absence of aquatic vegetation along research transects in 2020. Tracking regeneration of aquatic vegetation is a focus of future research as unknown effects from prolonged exposure to record-high water levels may affect natural regenerative processes at Allouez Bay, and potentially at other lacustrine Great Lakes wetlands throughout the basin. [ABSTRACT FROM AUTHOR]

• Shoreline landscapes are important yet understudied social-ecological systems. • Social valuation of shoreline habitat ecosystem services in Gulf of Mexico, USA. • Surveyed 530 waterfront residents on relative performance of mangroves vs. marshes. • Geography, local environment, individual attitudes, and behaviors drove perceptions. • Social data needed to predict coastal landscape shifts under climate change. Coastal landscapes are rapidly changing due to both climate change and the decisions of waterfront landowners. For instance, the climate-driven encroachment of woody mangrove species into grassy marshland areas is predicted to impact coastal ecosystems, with consequences for the ecosystem services these landscapes provide to people. However, there is a dearth of knowledge concerning coastal resident perceptions of the effects of mangrove expansion on wetlands and their ecosystem services, which may impact residents' behavior around shorelines and landscape-level patterns. We surveyed waterfront residents in the northern Gulf of Mexico (USA) to understand perceptions of the relative performance of marshes and mangroves to deliver fisheries ecosystem services. Residential-scale shoreline condition and preference, recreational fishing activity, geography, and demographics were evaluated as potential predictors of resident perceptions through non-parametric comparisons across groups and ordered logit modeling. Significant predictors included area of residence, marsh shoreline condition, marsh shoreline preference, fishing frequency, and household income. Florida residents (where mangroves are most prevalent) and frequent recreational fishing participants exhibited stronger preference for mangroves. Unexpectedly, residents with marsh currently present on their shoreline also perceived that mangroves were better at delivering fisheries ecosystem services than marshes. Considering the important role that coastal residents play in shoreline management decisions, these results demonstrate how coastal resident attitudes may drive or mediate climate-driven processes in ways that are not evident by examining environmental conditions alone. Understanding social-ecological shifts due to climate change will be important to inform effective landscape management that promotes resilience in coastal ecosystems and societies. [ABSTRACT FROM AUTHOR]