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Water diversions that support agricultural and municipal use result in fish mortality through entrainment and impingement. Additionally, this infrastructure may attract both predators and prey fishes, thereby increasing predation rates and prey mortality near these anthropogenic contact points. The Sacramento–San Joaquin Delta (the Delta) in California's Central Valley is a tidal freshwater ecosystem that exports large volumes of water for municipal and agricultural use while at the same time providing valuable migratory and rearing habitat for imperilled fishes. Emigrating juvenile salmonids experience high mortality in the Delta, with predation by non‐native fishes contributing substantially. Therefore, this study had three main objectives. First, we determined if small water diversions aggregated piscivorous fishes like other similar structures in freshwater ecosystems. Second, we determined how small diversions may influence juvenile salmon predation risk in conjunction with other known predation risk factors (e.g. predator abundance, temperature and depth). Third, we assessed the predator assemblage, abundance and distribution to determine the likely predator composition in objectives one and two. Throughout the spring of 2021, we used ARIS (adaptive resolution imaging sonar; Sound Metrics) sonars to compare piscivore abundance at 30 water diversions in the north Delta to shorelines adjacent to diversions that did not contain these structures. We used predation event recorders (PERs) to assess the predation risk juvenile salmonids were exposed to, with linear distance (m) from diversions, and other predation risk factors in the north Delta. Finally, we used a boat electrofishing survey to determine the piscivore assemblage and compare spatial trends in black bass (Micropterus spp.) CPUE and relative abundance throughout these waterways. Piscivore abundance was greater near small water diversions than at adjacent shorelines and the predation risk of juvenile salmonids increased with diversion proximity. Additionally, predation risk increased with increasing piscivore abundance and decreasing water depth. The north Delta predator assemblage was dominated by black basses (Micropterus spp.), which likely drove the negative relationship of predation risk with water depth, given habitat requirements of these species. Furthermore, increasing smallmouth (Micropterus dolomieu) and spotted bass (Micropterus punctulatus) abundance in our northern study sites may have weakened temperature effects on predation, given metabolic requirements of these species. Our work demonstrated that small water diversions are likely to increase mortality of endangered salmonids, and that the north Delta predator assemblage was different than recorded by previous work in this system, changing predation risk factors. Although more work is needed to determine the population level impacts of diversions, the ubiquitous distribution of these structures warrants management solutions to reduce mortality from this source. These results indicate that in addition to entrainment and impingement, water diversions may increase mortality of small‐bodied fishes by attracting predators and elevating predation risk. Given the continual human demand for freshwater, predator–prey interactions should be considered along with entrainment and impingement when assessing intake infrastructure mitigation, especially when diversions co‐occur along migratory routes and essential habitat of imperilled fishes. [ABSTRACT FROM AUTHOR]

Sanmen Bay (SMB) is one of the important harbors in Zhejiang Province. It is a semi-enclosed shallow bay that has undergone large-scale land reclamation activities. Long-term reclamation has changed the hydrodynamic conditions of SMB, such as tide, residual current, tidal prism, water exchange capacity, and tidal asymmetry. In this study, three typical periods of numerical models, based on historical charts and remote sensing, were established to investigate the influence of reclamation activities on the hydrodynamic conditions of SMB from 1971 to 2020. These model results reveal that the amplitude and phase of M2, the main tidal components in SMB, decreased by ~0.1-0.3 m and ~ 5°-15°, respectively, over the last half-century. Additionally, under the influence of ~200 km2 reclamation, many hydrodynamic conditions in SMB also changed. This includes the reduction of a residual current and tidal prism, an increase in residence time, and a change in tidal asymmetry characteristics. The residence time in nearby Xiayangtu exhibited a downward trend from 2003 to 2020, because land reclamation squeezed, and thus, enhanced the residual current eddy. The water-exchange capacity of the bay became weaker with the reduction of tidal prism to one-third and an increase in residence time. The tidal asymmetry characteristic of SMB changed from half of flood dominant to fully flood dominant by the influence of shoreline and bathymetry, which raised the flood risk. Research on the response of the hydrodynamic environment to reclamation activities in SMB reminds the local government to reassess the impact of land reclamation on the hydrodynamic environment. [ABSTRACT FROM AUTHOR]

AbstractThe construction of an island airport on a coral reef will inevitably encounter wave, tidal and aircraft takeoff and landing loads. To study the dynamic response of the coral sand island airport under these loads, a 1:50 laboratory model test was conducted with Meiji Reef Airport as the engineering background. The model test studied the pore water pressure characteristics of the coral sand strata beneath the airport runway under wave loads with different wave heights, tidal loads with different tidal heights, and aircraft impact loads with different cyclic loading times. Additionally, the displacement characteristics of the coral sand strata beneath the airport runway under the aircraft impact loads with different cyclic loading times were also studied. The results show that the pore water pressure of coral sand strata under the airport runway decreases with the increasing offshore distance under the wave and tidal loads. The change of wave height has little influence on the pore water pressure of coral sand strata, while the change of tidal water level has a significant effect on it. As the number of aircraft impact load cycles increases, the cumulative excess pore pressure in the coral sand strata under the airport runway no longer increases and plastic deformation occurs. The research can provide a reference for the runway foundation treatment of the island airport under construction and planning. [ABSTRACT FROM AUTHOR]

Mangroves store significant amounts of carbon in both sediment and water. Methane (CH4) is often produced in anoxic, organic‐rich sediments during carbon degradation and released to overlying waters via porewater exchange. Yet, a portion of CH4 can be oxidized to CO2 before emission. Here, we investigate whether CH4 oxidation impacts its emissions using high‐temporal resolution CH4 concentration and stable isotope (δ13C‐CH4) observations collected over 14 tidal cycles in 2 Brazilian mangrove creeks with no river inputs. We found higher CH4 concentrations (~ 150 nM) more depleted in 13C (−75‰) during low tide than high tide at both creeks. Similar δ13C‐CH4 values between low tide surface waters and porewaters further suggest tidally driven porewater exchange as the main source of CH4. More 13C‐enriched CH4 in surface waters and surface sediments than deep sediments indicate partial CH4 oxidation prior to exchange with the atmosphere. A stable isotope mass balance revealed that 17–58% of CH4 was oxidized at rates of 3–25 μmol m−2 d−1 in the water column of tidal creeks. A larger portion of deep porewater CH4 (45–61%) was oxidized in sediments prior to porewater exchange with surface creek waters. The two mangrove creeks had average water–air CH4 fluxes of 51–109 μmol m−2 d−1 over spring‐neap tidal cycles. These aquatic CH4 emissions offset only < 3% of the mangroves' soil carbon sequestration. Overall, CH4 oxidation in both surface water and sediment attenuated CH4 emissions to the atmosphere. [ABSTRACT FROM AUTHOR]

Like many coastal lagoons in several countries, the "Navío Quebrado" lagoon (La Guajira, Colombia) is a very delicate and precious environment; indeed, it is a nationally recognized Flora and Fauna Sanctuary. Several factors, including climate change, are threatening its existence because of changes in the governing hydro-morphological and biological processes. Certainly, the first step to addressing this problem is to understand its hydrological behavior and to be able to replicate, via simulation, its recent history before inferring likely futures. These potential futures will be marked by changes in the water input by its tributary, the Camarones River, and by modified water exchange with the sea, according to a foreseen sea level rise pattern, as well as by a different evaporation rate from the free surface, according to temperature changes. In order to achieve the required ability to simulate future scenarios, data on the actual behavior have to be gathered, i.e., a monitoring system has to be set up, which to date is non-existent. Conceptually, designing a suitable monitoring system is not a complex issue and seems easy to implement. However, the environmental, socio-cultural, and socio-economic context makes every little step a hard climb. An extremely simple—almost "primitive"—monitoring system has been set up in this case, which is based on very basic measurements of river flow velocity and water levels (river, lagoon, and sea) and the direct participation of local stakeholders, the most important of which is the National Park unit of the Sanctuary. All this may clash with the latest groovy advances of science, such as in situ automatized sensors, remote sensing, machine learning, and digital twins, and several improvements are certainly possible and desirable. However, it has a strong positive point: it provides surprisingly reasonable data and operates at almost zero additional cost. Several technical difficulties made this exercise interesting and worthy of being shared. Its novelty lies in showing how old, simple methods may offer a working solution to new challenges. This humble experience may be of help in several other similar situations across the world. [ABSTRACT FROM AUTHOR]

Soil temperature regulates biogeochemical processes and is a key environmental factor affecting salt marsh ecosystems. Previous studies on soil temperature and heat transport in intertidal marshes predominantly focused on short‐term changes, leaving seasonal variations unclear. This study conducted a yearlong field and modeling investigation to examine temporal and spatial temperature variations in a creek‐marsh section under estuarine and meteorological influences. The results showed that inundating tidal water propagated the seasonal water temperature signal to marsh soils, especially at low elevations, thereby modulating air temperature‐induced soil temperature variations and distributions. The response of soil temperature to air and tidal water temperatures exhibited a damped and delayed pattern. In contrast, tide‐induced porewater circulations near the creek facilitated the temperature responses. A regression model incorporating a Gamma distribution function was developed to quantify the delayed and cumulative thermal effects of tidal water and air on shallow soil temperatures. The model coefficients varied along the creek‐marsh section, capturing the seasonal regulation of periodic tidal inundation on soil temperature in the low‐elevation marsh and near the creek. Sensitivity analyses indicated that relative sea level rise lowered yearly‐averaged temperatures for the marsh platform by enhancing latent heat export. Surface water warming increased the marsh temperatures at lower elevations. This study demonstrates that the creek‐marsh topography, warming, and relative sea level rise jointly affect soil temperature dynamics, advancing our understanding of temperature‐dependent biogeochemical processes in marsh ecosystems. Key Points: Seasonal temperature distributions along a creek‐marsh section were identifiedShallow soil temperature dynamics were predominated by seasonal tidal water and air temperaturesRelative sea level rise decreased the yearly‐averaged temperature in the high‐elevation marsh [ABSTRACT FROM AUTHOR]

The Doñana Protected Area, Western Europe's largest protected wetland and UNESCO World Heritage Site, is of great importance for the Spanish biodiversity. Despite its ecological value, there is a noticeable scarcity of scientific and technical information about its hydrology and expected climate change effects, as highlighted by several authors. This article reviews the existing research on the Guadalquivir River and Doñana National Park, examining the interplay between hydrodynamics, climate change scenarios, and the potential impact of the removal of the current dike which was built to limit tidal flooding. In this context, the hydrodynamic changes predicted by a hydrodynamic model were examined under both present (including the current mean sea level and the presence of the dike) and predicted future conditions (encompassing a mean sea level rise of 0.84 m and the removal of the dike). These hydrodynamic changes were assessed in terms of the maximum predicted water levels, mean velocity, amplitude, and phase of M2 and M4 tidal constituents, tidal asymmetry, and tidal prims. The results reveal that the removal of the dike and a sea level rise will have a significant impact on the protected area, resulting in the complete flooding of the Doñana national marshes during spring tides. Such changes could have negative impacts, as increased environmental alterations would require more demanding adaptation measures. [ABSTRACT FROM AUTHOR]

Since 1958, there have been significant changes in the Yangtze River estuary. Due to extensive reclamation and construction of ports and channels, the water area has drastically decreased, resulting in corresponding changes in hydrodynamics and riverbeds at the mouth of the river. According to the analysis of measured topographic data and Delft3D-FLOW model for seven typical historical periods since 1958 at the Yangtze River Estuary, this study investigates the characteristics of riverbed evolution and tidal flow dynamics. From 1958 to 2019, driven by strong human activities, the total area of the Yangtze River Estuary decreased from 2084 km2 to 1403 km2, with a decrease of 32.7%, while the total volume of the corresponding river channel changed slightly and remained stable. Compared with 1958, the volume of the Yangtze River Estuary in 2019 only increased by 345 million m3, with an increase of about 4.1%. The tidal dynamic change of the Yangtze Estuary is closely related to the riverbed evolution of each reach, which not only shapes the estuary landform, but also is affected by the riverbed evolution. Tidal level, tidal range and water area change are closely related. With the decrease of water area in the Yangtze River Estuary, tidal range tends to increase. Tidal prism change is closely related to channel volume. In the past 60 years, the tidal volume at the mouth of the Yangtze River has decreased by 8%. The research findings will provide technical support for enhancing flood control and tide resistance measures at the Yangtze River Estuary, as well as formulating comprehensive management plans for estuaries, contributing to the protection and sustainable development of the Yangtze River Estuary. [ABSTRACT FROM AUTHOR]

A new calving algorithm is developed in the glacier model Elmer/Ice that allows unrestricted calving and terminus advance in 3D. The algorithm uses the meshing software Mmg to implement anisotropic remeshing and allow mesh adaptation at each time step. The development of the algorithm, along with the implementation of the crevasse depth law, produces a new full-Stokes calving model capable of simulating calving and terminus advance across an array of complex geometries. Using a synthetic tidewater glacier geometry, the model is tested to highlight the numerical model parameters that can alter calving when using the crevasse depth law. For a system with no clear attractor at a pinning point, the model time step and mesh resolution are shown to alter the simulated calving. In particular, the vertical mesh resolution has a large impact, increasing calving, as the frontal bending stresses are better resolved. However, when the system has a strong attractor, provided by basal pinning points, numerical model parameters have a limited effect on the terminus evolution. Conversely, transient systems with no clear attractors are highly influenced by the choice of numerical model parameters. The new algorithm is capable of implementing unlimited terminus advance and retreat, as well as unrestricted calving geometries, applying any vertically varying melt distribution to the front for use in conjunction with any calving law or potentially advecting variables downstream. In overcoming previous technical hurdles, the algorithm opens up the opportunity to improve both our understanding of the physical processes and our ability to predict calving. [ABSTRACT FROM AUTHOR]

Homestead windbreaks are used on the Ryukyu Islands to protect houses from the tidal water blowing from the sea, strong typhoons in the summer, and monsoonal winds in the winter. The homestead windbreak landscape is believed to have been established approximately 300 years ago in the Ryukyu Kingdom. Garcinia subelliptica (Fukugi in Japanese) was dominant in this windbreak landscape. These windbreaks vanished on several islands soon after World War II. Many trees were burned during the war and removed to extend village roads in rural and recent resort development projects. This study surveyed the present spatial distribution of the remaining homestead windbreaks and conducted a tree inventory survey. We recorded the location and characteristics of trees damaged by the powerful typhoon and tentatively explored the causes of tree and house damage through a case study of Yonaguni Island, where one of the world's biggest typhoons occurred. Homestead windbreaks facing the wind direction, tree characters of cavities, unsound branching, and combined tree trunks were the significant factors contributing to tree damage. The remnant homestead windbreak belts in Yonaguni Island were fragmented and not continuous and may not offer consistent wind protection since there are open gaps between the sections. It suggests windbreaks should be replanted in the direction of the wind, and regular checks of tree health and tree structure are needed to reduce typhoon damage. The results are used to propose guidelines for windbreak management and conservation. [ABSTRACT FROM AUTHOR]

A shallow water equations-based model with an improved local time-stepping (LTS) scheme is developed for modeling coastal hydrodynamics across multiple scales, from large areas to detailed local regions. To enhance the stability of the shallow water model for long-duration simulations and at larger LTS gradings, a prediction-correction method using a single-layer interface that couples coarse and fine time discretizations is adopted. The proposed scheme improves computational efficiency with an acceptable additional computational burden and ensures accurate conservation of time truncation errors in a discrete sense. The model performance is verified with respect to conservation and computational efficiency through two idealized tests: the spreading of a drop of shallow water and a tidal flat/channel system. The results of both tests demonstrate that the improved LTS scheme maintains precision as the LTS grading increases, preserves conservation properties, and significantly improves computational efficiency with a speedup ratio of up to 2.615. Furthermore, we applied the LTS scheme to simulate tides at grid scales of 40,000 m to 200 m for a portion of the Northwest Pacific. The proposed model shows promise for modeling cross-scale hydrodynamics in complex coastal and ocean engineering problems. [ABSTRACT FROM AUTHOR]

Antillean manatees (Trichechus manatus manatus) are endangered coastal, marine, and riverine megaherbivores with high environmental plasticity, constrained by tidal and seasonal water level cycles that affect access to food and fresh water. Accurate quantification of the species' habitat requirements, typically achieved through home range (HR) estimation, is required to implement area‐based conservation initiatives. In this study, we used GPS tracking data from 38 wild and captive‐rehabilitated released manatees to estimate HR using autocorrelated kernel density estimators (AKDE) and average time speed. We investigated whether body size, habitat type, sex and behavioural group influence home range size due to energy requirements, resources availability, a scramble‐competitive polygyny mating system, and adaptation to the wild. Eighteen manatees exhibited range‐resident behaviour, with a mean 95% home range of 72.96 km2 (± 218.52) and a median of 10.69 km2. The mean daily speed was estimated to be 13.47 km/day (± 4.16). Home range and body size were positively correlated, consistent with HR allometry theory. Long‐term tracked individuals showed a trend of increasing HR over time. Only four released animals (17.4%) were range‐resident, suggesting that they may need additional time to establish a home range. Individuals using only the marine environment had larger home ranges compared to mixed (marine and estuarine) and estuarine environments, probably due to freshwater availability. Our study contributes to the understanding of the factors driving manatee movement and provides more accurate estimates of area requirements, which can inform the establishment and zoning of marine protected areas. [ABSTRACT FROM AUTHOR]

The Greenland Ice Sheet is losing mass at increasing rates. Substantial amounts of this mass loss occur by ice discharge which is influenced by ocean thermal forcing. The ice sheet is surrounded by thousands of peripheral, dynamically decoupled glaciers. The mass loss from these glaciers is disproportionately high considering their negligible share in Greenland' overall ice mass. We study the relevance of ocean thermal forcing for ice discharge evolution in the context of this contrasting behaviour. Our estimate of ice discharge from the peripheral tidewater glaciers yields a rather stable Greenland-wide mean of 5.40 ± 3.54 Gt a−1 over 2000–2021. The evolutions of ice discharge and ocean thermal forcing are heterogeneous around Greenland. We observe a significant sector-wide increase of ice discharge in the East and a significant sector-wide decrease in the Northeast. Ocean thermal forcing shows significant increases along the northern/eastern coast, while otherwise unchanged conditions or decreases prevail. For East Greenland, this implies a clear influence of ocean thermal forcing on ice discharge. Similarly, we find clear influences at peripheral tidewater glaciers with thick termini that are similar to ice sheet outlet glaciers. At the peripheral glaciers in Northeast Greenland ice discharge evolution opposes ocean thermal forcing for unknown reasons. [ABSTRACT FROM AUTHOR]

Salinity dynamics in the Delaware Bay estuary are a critical water quality concern as elevated salinity can damage infrastructure and threaten drinking water supplies. Current state‐of‐the‐art modeling approaches use hydrodynamic models, which can produce accurate results but are limited by significant computational costs. We developed a machine learning (ML) model to predict the 250 mg L−1 Cl− isochlor, also known as the "salt front," using daily river discharge, meteorological drivers, and tidal water level data. We use the ML model to predict the location of the salt front, measured in river miles (RM) along the Delaware River, during the period 2001–2020, and we compare predictions of the ML model to the hydrodynamic Coupled Ocean–Atmosphere‐Wave‐Sediment Transport (COAWST) model. The ML model predicts the location of the salt front with greater accuracy (root mean squared error [RMSE] = 2.52 RM) than the COAWST model does (RMSE = 5.36); however, the ML model struggles to predict extreme events. Furthermore, we use functional performance and expected gradients, tools from information theory and explainable artificial intelligence, to show that the ML model learns physically realistic relationships between the salt front location and drivers (particularly discharge and tidal water level). These results demonstrate how an ML modeling approach can provide predictive and functional accuracy at a significantly reduced computational cost compared to process‐based models. In addition, these results provide support for using ML models in operational forecasting, scenario testing, management decisions, hindcasting, and resulting opportunities to understand past behavior and develop hypotheses. [ABSTRACT FROM AUTHOR]

Ecological disturbances such as fish kills can negatively impact ecosystem processes in coastal lagoons. To gain an understanding of factors causing fish kills, we examined conditions associated with a summertime fish kill in a northeastern Pacific coastal lagoon (Rodeo Lagoon, CA, USA). Examination of available data indicated the fish kill was likely caused by hypoxia involving the following etiology: (1) strong onshore winds (up to 12 m/s) mixed a stratified water column, (2) water column mixing transported nutrients from near the bed into the photic zone, (3) increased nutrient concentrations in the photic zone (> 200%) together with high solar irradiance fueled a phytoplankton bloom, (4) death and decomposition of phytoplankton (72% decrease in abundance) contributed to biological oxygen demand that led to (5) hypoxic conditions (as low as 0.6 mg/L) that caused the fish kill. The event resulted in the death of an estimated 3677 Tidewater Goby (Eucyclogobius newberryi), a species listed as endangered under the US Endangered Species Act, and numerous (but not enumerated) Threespine Stickleback (Gasterosteus aculeatus), unidentified sculpins (Cottidae), and macroinvertebrates (primarily Amphipoda). The processes contributing to the event are likely re-occurring phenomena responsible for observed periodic fish kills. Coastal lagoons with limited freshwater inflows and connection to the Pacific Ocean may retain nutrients and be susceptible to similar events. [ABSTRACT FROM AUTHOR]

The tidal section of the Feiyun River is affected by the dual effects of the upstream flood discharge and downstream tidal uplift, resulting in complex water level changes. To determine the extreme water levels of the tidal section, the methods of the statistical analysis, harmonic calculation and joint probability analysis are utilized to study the correlation between the water level changes and the downstream estuarine tides and upstream floods based on the observation data and explore the extreme water level characteristics caused by flood-tide encounters. The study results indicate that the interannual water level correlation between Rui'an Hydrological Station and the up-downstream is not significant, but the correlation of their monthly water levels is enhanced. During the rainy season, there is a positive correlation between the daily average water levels of the upstream and Rui'an Hydrological Station. The water levels at Feiyun River (Rui'an section) are more affected by the combined influence of the astronomical tides and storm surges than by the upstream runoffs and water levels. The main contributing factor to the extreme skew surges at Rui'an Hydrological Station is the offshore storm surges. There is a significant time difference between the upstream flood peaks and the skew surge peaks at Rui'an Hydrological Station. The skew surge peaks at Rui'an Hydrological Station are at the forefront of the flood peaks superimposed by the extreme skew surges of the storm surges. The combined maximum total water levels for 1 year, 5 years, 10 years and 50 years calculated by the joint probability analysis method are 4.16 m, 4.44 m, 4.59 m and 4.90 m, respectively, which are basically consistent with the analysis results of measured data in the past 50 years. According to the joint probability distribution of the storm surges and astronomical tides, the reliability of short period calculation results is relatively high. [ABSTRACT FROM AUTHOR]

Salt marshes play a critical role in supporting water quality, erosion control, flood protection, and carbon sequestration. Threats from climate change and human activities have prompted global restoration initiatives. We analyzed restoration efforts worldwide from 1978 to 2022, using the Web of Science database and SciMAT mapping tool. After a PRISMA screening to identify methodologies, success rates, and key indicators, a total of 62 publications underwent detailed analysis, to increase knowledge on the best practices to employ in future restoration interventions and evaluation of their effectiveness. The research reveals a growing interest in ecosystem dynamics, biodiversity, anthropogenic impacts, and ecosystem services. Assisted interventions emerged as the predominant restoration method, employing 15 indicators across vegetation, sediment, fauna, and water, each one using different metrics for the intervention evaluation based on how good the outcome of the interventions described in the reviewed studies met the desired result. Our analysis suggests that combining natural interventions such as managed realignment with reconnection to tidal waters, along with long-term monitoring of vegetation, fauna, and water indicators such as sedimentation and erosion rates, plant cover and biomass, as well as fauna diversity and density, leads to the most successful outcomes. We provide valuable insights into best practices for future restoration interventions, offering guidance to future practitioners and policymakers based on a comprehensive review of the scientific literature, contributing to the resilience of these vital ecosystems, and ensuring effective restoration actions in the coming years. [ABSTRACT FROM AUTHOR]

Monitoring changes in glacial dynamics is essential for understanding the environmental response to accelerated climate warming in the Arctic. However, geodetic surveys in polar regions continue to present considerable challenges because of the harsh environmental conditions and the polar night. This study records a 14-year-long time series (2006–2019) of global navigation satellite system (GNSS) surveys of the positions of 16 ablation stakes distributed across Hansbreen, a tidewater glacier in southern Svalbard. The measurements were conducted with an exceptionally high temporal resolution, from about 1 week to about 1 month, and covering altitudes ranging from 20 to 490 m a.s.l. The position of one stake was surveyed every day. The primary data products consist of the stake coordinates and velocities. Time series of annual and seasonal velocities are also provided. This dataset may be a subject of further studies of glacier dynamics in relation to the long-term and seasonal impact of climate change on ice flow in the region. It also offers unique material for tuning numerical models of glacier dynamics and for validating satellite-derived products such as velocity and digital elevation models. The dataset described here has been made publicly available through the Zenodo repository: 10.5281/zenodo.8289380 (Błaszczyk et al., 2023). [ABSTRACT FROM AUTHOR]

In 2020, the Chesapeake Bay Program moved to offset impacts from climate change for the 30‐year period from 1995 through 2025 by having its seven watershed jurisdictions (Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia, and the District of Columbia) apply additional nutrient pollutant reduction practices. The climate change assessment was performed with integrated models of the Chesapeake watershed, airshed, and estuary. Scenarios run for the years 2025, 2035, 2045, and 2055 estimated effects from the different future climatic conditions. This article presents the results of that assessment and is intended to provide a guide to assist other modeling practitioners in assessing climate change impacts in coastal watersheds. Major influences of climate change that were quantified include increases in precipitation volume, potential evapotranspiration, watershed nutrient loads, tidal water temperature, and sea level. Minor influences quantified in the climate change analysis include changes in nutrient speciation and increases in wet deposition of nitrogen, CO2, rainfall intensity, tidal wetland loss, up‐estuary salt intrusion, and phytoplankton biomass. To offset climate change impacts from 1995 to 2025 on water quality, the scenarios indicate an additional 2.3 million and 0.3 million kg of nitrogen and phosphorus per annum, respectively, will need to be reduced beyond what is called for in the Chesapeake Total Maximum Daily Load. [ABSTRACT FROM AUTHOR]

The hundreds of tidewater glaciers found in the Canadian Arctic Archipelago have the potential to enhance delivery of nutrients and other material to the surface ocean. Despite this, their influence on marine ecosystems, specifically phytoplankton, is poorly characterized. Here we developed and applied a quantitative mass spectrometry‐based approach to measure phytoplankton ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) concentrations to examine differences in productivity in glacierized and non‐glacierized marine systems in Jones Sound, Nunavut, within Inuit Nunangat. Comparisons to chloroplast 16S rRNA gene amplicon sequencing data suggested that these measurements detect the majority of Rubisco produced in Jones Sound. Because Rubisco catalyzes carbon fixation, we used these measurements to estimate total and group‐specific primary production potential, which were within the range of historical primary production measurements made using classical methods in this region. Our measurements also revealed that up to 2% of total protein in the water column is Rubisco, and that Rubisco concentrations are correlated with chlorophyll fluorescence, with maxima near the nitracline. Rubisco produced by diatom genera Chaetoceros and Thalassiosira were higher in marine regions influenced by glaciers, while Rubisco from Micromonas (Chlorophyta) was greater in non‐glacierized regions. This suggests that future climate scenarios may favor smaller phytoplankton groups, like Micromonas, with consequences for food webs and carbon cycling. This study broadens our understanding of how tidewater glaciers will impact phytoplankton communities, now and in a warmer future, and lays the foundation for using this mass spectrometry‐based approach to quantify phytoplankton group‐specific carbon fixation potential in other marine regions. [ABSTRACT FROM AUTHOR]

Glacial fjords often contain ice mélange, a frozen conglomeration of icebergs, brash ice, and sea ice, that have been postulated to influence both glacier dynamics and fjord circulation through coupled mechanical and thermodynamic processes. Ice mélange meltwater can alter stratification of the water column by releasing cool, fresh water across a range of depths in the upper layer of the fjord. This meltwater input can subsequently modify the depth at which the subglacial discharge plume reaches neutral buoyancy and therefore the underlying buoyancy-driven fjord circulation and heat exchange with warm ocean shelf waters. Despite a spate of recent modelling studies exploring these proposed feedbacks, we lack in situ observations quantifying changes to the water column induced by ice mélange meltwater. Here we use a novel dataset collected before and after the melt, breakup, and down-fjord transport of an ephemeral ice mélange in front of Kangilliup Sermia (Rink Isbræ) to directly investigate the extent to which ice mélange meltwater can modify glacier-adjacent water properties. We find that even a short-lived ice mélange (4 days) can cause substantial cooling (0.18 °C) and freshening (0.25 g kg-1) of the water column that leads to stratification change down to the depth of the outflowing discharge plume. We compare our observations to an adjacent fjord, Kangerlussuup Sermia, where ice mélange seldom forms in the summertime, and show that the presence or absence of ice mélange melt creates fundamental differences in their upper layer hydrography. These observations provide critical constraints for recent modelling studies that have suggested ice mélange meltwater needs to be included in ocean circulation models for glaciers with deep grounding lines and high ice fluxes, which are precisely the glaciers exhibiting the largest magnitude terminus retreats at present. [ABSTRACT FROM AUTHOR]

Tide-surge interaction (TSI) plays a substantial role in determining the characteristics of surges over shallow regions. A variety of approaches have been used to study TSI globally, and TSI have been found to occur in Singapore and the east coast of Peninsular Malaysia. However, the characteristics of TSI in Singapore and the east coast of Peninsular Malaysia have yet to be studied in detail. We study the TSI at seven tide gauges along the east coast of Peninsular Malaysia and Singapore. Here, we propose a modified statistical framework that accounts for irregularity in the tidal cycle. We find evidence of TSI at all seven locations, with characteristics varying smoothly along the coastline: the highest non-tidal residuals are found to occur most frequently before tidal high water at the southern region of this coastline and in Singapore, both before and after tidal high water in the middle of the coastline, and after tidal high water at the northern region. We also propose a semi-empirical model to investigate the effects of tidal phase alteration, which is one the mechanisms of TSI. Results of our semi-empirical model reveal that tidal phase alteration caused by wind-driven surges is substantial enough to generate significant change in the timing of the largest surges. [ABSTRACT FROM AUTHOR]

Tide-surge interaction (TSI) plays a substantial role in determining the characteristics of surges over shallow regions. A variety of approaches have been used to study TSI globally, and TSI have been found to occur in Singapore and the east coast of Peninsular Malaysia. However, the characteristics of TSI in Singapore and the east coast of Peninsular Malaysia have yet to be studied in detail. We study the TSI at seven tide gauges along the east coast of Peninsular Malaysia and Singapore. Here, we propose a modified statistical framework that accounts for irregularity in the tidal cycle. We find evidence of TSI at all seven locations, with characteristics varying smoothly along the coastline: the highest non-tidal residuals are found to occur most frequently before tidal high water at the southern region of this coastline and in Singapore, both before and after tidal high water in the middle of the coastline, and after tidal high water at the northern region. We also propose a semi-empirical model to investigate the effects of tidal phase alteration, which is one the mechanisms of TSI. Results of our semi-empirical model reveal that tidal phase alteration caused by wind-driven surges is substantial enough to generate significant change in the timing of the largest surges. [ABSTRACT FROM AUTHOR]

Frontal ablation has caused 32 %–66 % of Greenland Ice Sheet mass loss since 1972, and despite its importance in driving terminus change, ocean thermal forcing remains crudely incorporated into large-scale ice sheet models. In Greenland, local fjord-scale processes modify the magnitude of thermal forcing at the ice–ocean boundary but are too small scale to be resolved in current global climate models. For example, simulations used in the Ice Sheet Intercomparison Project for CMIP6 (ISMIP6) to predict future ice sheet change rely on the extrapolation of regional ocean water properties into fjords to drive terminus ablation. However, the accuracy of this approach has not previously been tested due to the scarcity of observations in Greenland fjords, as well as the inability of fjord-scale models to realistically incorporate icebergs. By employing the recently developed IceBerg package within the Massachusetts Institute of Technology general circulation model (MITgcm), we here evaluate the ability of ocean thermal forcing parameterizations to predict thermal forcing at tidewater glacier termini. This is accomplished through sensitivity experiments using a set of idealized Greenland fjords, each forced with equivalent ocean boundary conditions but with varying tidal amplitudes, subglacial discharge, iceberg coverage, and bathymetry. Our results indicate that the bathymetric obstruction of external water is the primary control on near-glacier thermal forcing, followed by iceberg submarine melting. Despite identical ocean boundary conditions, we find that the simulated fjord processes can modify grounding line thermal forcing by as much as 3 °C , the magnitude of which is largely controlled by the relative depth of bathymetric sills to the Polar Water–Atlantic Water thermocline. However, using a common adjustment for fjord bathymetry we can still predict grounding line thermal forcing within 0.2 °C in our simulations. Finally, we introduce new parameterizations that additionally account for iceberg-driven cooling that can accurately predict interior fjord thermal forcing profiles both in iceberg-laden simulations and in observations from Kangiata Sullua (Ilulissat Icefjord). [ABSTRACT FROM AUTHOR]

Many studies have shown that environmental DNA (eDNA) sampling can be more sensitive than traditional sampling. For instance, past studies found a specific qPCR probe of a water sample is better than a seine for detecting the endangered northern tidewater goby, Eucyclogobius newberryi. Furthermore, a metabarcoding sample often detects more fish species than a seine detects. Less consideration has been given to sampling costs. To help managers choose the best sampling method for their budget, I estimated detectability and costs per sample to compare the cost effectiveness of seining, qPCR and metabarcoding for detecting endangered tidewater gobies as well as the associated estuarine fish community in California. Five samples were enough for eDNA methods to confidently detect tidewater gobies, whereas seining took twice as many samples. Fixed program costs can be high for qPCR and seining, whereas metabarcoding had high per-sample costs, which led to changes in relative cost-effectiveness with the number of locations sampled. Under some circumstances (multiple locations visited or an already validated assay), qPCR was a bit more cost effective than metabarcoding for detecting tidewater gobies. Under all assumptions, seining was the least cost-effective method for detecting tidewater gobies or other fishes. Metabarcoding was the most cost-effective sampling method for multiple species detection. Despite its advantages, metabarcoding has gaps in sequence databases, can yield vague results for some species, and can lead novices to serious errors. Seining remains the only way to rapidly assess densities, size distributions, and fine-scale spatial distributions. [ABSTRACT FROM AUTHOR]

This study delves into the sedimentation mechanisms governing mud deposits in shallow marine and tidal environments, with a particular focus on elucidating the versatile therapeutic applications of these muds. This research provides valuable insights for optimizing the selection of mud as a cosmetic resource that can positively influence human health and well-being by utilizing a comprehensive analysis involving CaCO3, TOC, grain size, and statistical parameters across six outcrops situated on the Kefalonia and Corfu islands. The research reveals that the CaCO3 content of mud deposits on both islands is comparable. Despite the average value (26.71%) significantly exceeding the recommended value (10%) for optimal plasticity, no discernible impact on the mechanical behavior and plasticity of the clay was observed, rendering it a neutral quality criterion. Notably, the TOC content is higher on Corfu Island, suggesting its potential superiority for mud therapy. However, all samples exhibit a TOC content (<0.77%) considerably below the threshold required (2–5%) for material maturation in mud therapy. Consequently, an enrichment of samples with organic matter is imperative. The application of statistical parameters, analyzed through graphical methods, facilitated the creation of various bivariate diagrams, offering insights into the prevailing environmental conditions during deposition. Linear and multigroup discriminant analyses categorize two sediment types: a unimodal type, characterized by mud grain-size dominance, deposited in a shallow water environment, and a bi-modal type, featuring mud and sand content, deposited in a tidal-affected environment. This classification underscores the potential of shallow marine muds (Kefalonia Island) for therapeutic use, given their optimal grain size. In contrast, the tidal mud (Corfu Island), while also suitable for mud therapy, necessitates processing as a cosmetic product to minimize sand content, as coarser fractions may induce skin irritations or injuries. [ABSTRACT FROM AUTHOR]

Intertidal sediments are rich in biological resources, which are important for material circulation and energy exchange. Meanwhile, these areas can be treated as sinks as well as sources of coastal heavy metal pollutants. Due to the influence of the tide, the intertidal sediments are in a state of periodic flooding and exposure, and environmental factors such as dissolved oxygen, salinity and overlying water pressure are changeable. Heavy metals in sediments are prone to migration and transformation with the dynamic effects of tidal water and the changes in the environment factors, which increase the bioavailability of heavy metals. In this review, the characteristics of distribution and the bioavailability of heavy metals in intertidal sediments are described; the migration and transformation behavior of heavy metals and its influencing factors under tidal conditions are analyzed; and the mechanisms of heavy metal's migration and transformation in the intertidal zone are summarized. Moreover, the bioaccumulation of heavy metal by organisms and the remediation techniques are discussed. Therefore, this review systematically summarizes the states of existence, the transport mechanisms, and the fate of heavy metals in the intertidal sediment, fills in the research gap of the cycling of heavy metal in the intertidal zone, and provides a theoretical basis for the control of heavy metal pollution. [ABSTRACT FROM AUTHOR]

Dragonfly nymphs breathe water using tidal ventilation, a highly unusual strategy in water-breathing animals owing to the high viscosity, density and low oxygen (O2) concentration of water. This study examines how well these insects extract O2 from the surrounding water during progressive hypoxia. Nymphs were attached to a custom-designed respiro-spirometer to simultaneously measure tidal volume, ventilation frequency and metabolic rate. Oxygen extraction efficiencies (OEE) were calculated across four partial pressure of oxygen (pO2) treatments, from normoxia to severe hypoxia. While there was no significant change in tidal volume, ventilation frequency increased significantly from 9.4 ± 1.2 breaths per minute (BPM) at 21.3 kPa to 35.6 ± 2.9 BPM at 5.3 kPa. Metabolic rate increased significantly from 1.4 ± 0.3 µl O2 min−1 at 21.3 kPa to 2.1 ± 0.4 µl O2 min−1 at 16.0 kPa, but then returned to normoxic levels as O2 levels declined further. OEE of nymphs was 40.1 ± 6.1% at 21.3 kPa, and did not change significantly during hypoxia. Comparison to literature shows that nymphs maintain their OEE during hypoxia unlike other aquatic tidal-breathers and some unidirectional breathers. This result, and numerical models simulating experimental conditions, indicate that nymphs maintain these extraction efficiencies by increasing gill conductance and/or lowering internal pO2 to maintain a sufficient diffusion gradient across their respiratory surface. [ABSTRACT FROM AUTHOR]

Anthropogenic alterations have paramount impacts on the alpha and beta diversity of aquatic resources, and fishes are predominantly susceptible to such impacts. Mahanadi River, one of the major peninsular rivers of India, has abundant fish resources, which play a significant role in supporting the fishers' livelihoods. The exploratory study in the river conducted for three consecutive years recorded 148 species under 53 families. Cyprinids dominated the fish diversity with 41 species, followed by Bagrids (9) and Sciaenids (7). One hundred-one species under 29 families were reported from the freshwater stretch. With a total of 111 species reported under 48 families, the estuarine and tidal freshwater stretch was more speciose, due to marine migrant species which advent the estuarine and tidal freshwaters stretch for breeding and feeding purposes. Tikarpara, a conserved site within a sanctuary, was the most species-diverse as well as a species-even site. The study also recorded the extension of the distributional range of 3 fish species and also 4 exotic species from the river. The seasonal variations in diversity indicated that the deviations were not prominent in freshwater sites, whereas in tidal brackish water sites, species richness was relatively higher in post-monsoon, and species evenness was higher during monsoon. Taxonomic distinctness test showed that the average taxonomic distinctness was high for tidal estuarine locations as they harbour taxonomically distant fishes. The hierarchical clustering of sites showed the inordinate effect of river gradient and fragmentation on the fish community structure. Analyzing the key drivers of the assemblage structure of the entire river, salinity was the major deterministic factor, and within the freshwater stretch, the major influences were depth, transparency, and specific conductivity. The study concluded that, despite all of its ecological stresses, Mahanadi still supports rich fish diversity, yet there is a notable shift in the fish community structure. There is a need for integrating molecular and morphological tools for the taxonomic revision of many genera and species for proper in situ and ex situ conservation measures and to formulate future biodiversity management plans addressing to reduce the impacts of the ecological threats. [ABSTRACT FROM AUTHOR]

The simple scaling relation for internal-tide generation proposed by Jayne and St. Laurent is widely used for parameterizing turbulent mixing induced by breaking of internal tides. Based on the internal-tide generation derived from a 0.1° ocean general circulation model, we show that depending on which stratification is used, this relation produces different vertical distributions of internal-tide generation. When using the buoyancy frequency at the seafloor, which is a common practice, the scaling relation produces, relative to the model, too-strong internal-tide generation in the upper 2000 m and too-weak internal-tide generation in the lower 2000 m. Moreover, the different vertical distributions in the different ocean basins, characterized by a generally decreasing internal tide generation with increasing depth in the Indo-Pacific but not-decreasing or even increasing internal tide generation with increasing depth in the upper 3000 m of the Atlantic, cannot be captured when using bottom stratification. These unsatisfactory features can be easily removed by replacing the buoyancy frequency at the seafloor by a buoyancy frequency averaged over a large part of the water column. To our knowledge, this sensitivity to stratification has not been explicitly quantified for the global ocean. Because of this sensitivity, the scaling relation of Jayne and St. Laurent should be used with an averaged stratification to ensure a more adequate representation of turbulent diffusivity due to tidal mixing and water mass transformation in the deep oceans. [ABSTRACT FROM AUTHOR]

The Salish Sea is a large, fjordal estuarine system opening onto the northeast Pacific Ocean. It develops a strong estuarine exchange flow that draws in nutrients from the ocean and flushes the system on timescales of several months. It is difficult to apply existing dynamical theories of estuarine circulation there because of the extreme bathymetric complexity. A realistic numerical model of the system was manipulated to have stronger and weaker tides to explore the sensitivity of the exchange flow to tides. This sensitivity was explored over two timescales: annual means and the spring‐neap. Two theories for the estuarine exchange flow are: (a) "gravitational circulation" where exchange is driven by the baroclinic pressure gradient due to along‐channel salinity variation, and (b) "tidal pumping" where tidal advection combined with flow separation forces the exchange. Past observations suggested gravitational circulation was of leading importance in the Salish Sea. We find here that the exchange flow increases with stronger tides, particularly in annual averages, suggesting it is controlled by tidal pumping. However, the landward salt transport due to the exchange flow decreases with stronger tides because greater mixing decreases the salinity difference between incoming and outgoing water. These results may be characteristic of estuarine systems that have rough topography and strong tides. Plain Language Summary: The circulation of water in Salish Sea flushes the system with ocean water over a few months, much faster than could be explained by rivers alone. This flushing, or "exchange flow," is important because it brings in ocean nutrients to grow phytoplankton, and because it removes pollution. To understand why the exchange flow is as big as it is we analyzed the results of a realistic computer simulation. We found that tidal currents were important, but in competing ways. Stronger tides generally enhanced the exchange of water by forcing tidal eddies at places like sills. However stronger tides also increased vertical mixing, so the water in the eddies was just stirring the same water back and forth, instead of systematically bringing in ocean water and sending out river water. Key Points: The volume transport of the estuarine exchange flow in the Salish Sea increases with stronger tidal transportHowever, the landward salt transport due to the estuarine exchange flow decreases with stronger tidal transport [ABSTRACT FROM AUTHOR]

Since the 1970s, extensive land reclamation has been carried out in the Bohai Sea. However, reclamation activities were prohibited in 2018. Using the MIKE3 numerical model, this study selected 1976 and 2018 as representative years before and after reclamation, respectively, and developed a highly accurate three‐dimensional hydrodynamic and sediment transport model for the Bohai Sea. The model was employed to access the effects of reclamation on tidal waves, tidal prism, residual current, tidal flux (TF), and suspended sediment flux (SSF). The results revealed that after reclamation, the amphidromic points of M2 and S2 shifted southward near Qinhuangdao, and eastward near the Yellow River estuary. The M2 amplitude in the Bohai Bay exhibited a maximum increase of 30 cm. In the Bohai Sea, the tidal prism decreased by 3.95%, suggesting a decrease in water exchange capacity. The TF in the Bohai Sea and Laizhou Bay decreased by 0.7% and 12%, respectively, while increasing by 16% in Bohai Bay and 12% in Liaodong Bay, primarily due to the variations in tidal waves. Furthermore, SSF decreased by 6% in the Bohai Sea, but increased by 125% in Bohai Bay and 114% in Laizhou Bay. The significant increase in SSF in Bohai Bay and Laizhou Bay was mainly attributed to the higher suspended sediment concentrations and the stronger residual current velocities near the Yellow River estuary. This study provides comprehensive insights into the impacts of reclamation on TF and SSF in the Bohai Sea, which could contribute to marine resource development and the planning of environmental restoration projects. Plain Language Summary: In the Bohai Sea, land reclamation has been accelerated since 1970s. Due to negative effects on aquaculture and channel, reclamation activities were prohibited in 2018. However, no research on annual tidal flux (TF) and suspend sediment flux (SSF) in the Bohai Sea has been reported. We have established high‐precision hydrodynamic and sediment transport model to analyze the impacts of reclamation on TF and SSF in the Bohai Sea. The findings revealed that reclamation led to a decrease in TF in the Bohai Sea and Laizhou Bay, while caused an increase in TF in Bohai Bay and Liaodong Bay. After reclamation, the SSF decreased in the Bohai Sea, while increased in Bohai Bay, Laizhou Bay and Liaodong Bay. After reclamation, the suspended sediment concentration and residual current velocity near the Yellow River estuary increased significantly, which was the main reason for the significant increase of SSF in Bohai Bay and Laizhou Bay. The Bohai Sea served as both the "source" of Yellow Sea muddy area and the "sink" of Yellow River which carried a large amount of sediment. The research on how reclamation affecting the TF and SSF in the Bohai Sea was essential for the sedimentation system of the East China Seas. Key Points: After reclamation, the area of Bohai Bay reduced, however, the tidal prism increased by nearly 10% due to the increase of tidal rangeAfter reclamation, tidal flux and water exchange capacity decreased in the Bohai Sea and Laizhou Bay, while increased in Bohai BayAfter reclamation, sediment flux decreased in the whole Bohai Sea and increased in three bays, particularly in Bohai Bay and Laizhou Bay [ABSTRACT FROM AUTHOR]

Water Diversion Projects have become increasingly popular in improving water quality in various water ecosystems. However, these projects also require a more comprehensive evaluation. In this study, we introduced a digital stable marker tracing module and proposed a continuation-dynamic constitution analysis approach. We applied this approach to analyze the ecological tidal water diversion in Changshu town, China. The results showed that the mean diversion water age of the Yangtze River water source was 10.80 h, the residence time of the background water source in Baimaotang was approximately 4.0 h, and the contribution of inflow water sources from tributaries accounted for 15% of discharges. The results can demonstrate practicality of our approach in quantitatively evaluating water diversion impacts and optimizing cooperative diversion projects. Furthermore, our discussion led to the design of an ecological tidal water diversion based on optimized cooperative diversion, which showed element-complementary and whole-comprehensive effects. This indicates that the ecological tidal water diversion can extend the impact of cooperative diversion. The continuation-dynamic constitution analysis approach enhances the tracing capacity of inflow constitution and enables the distinction of different time-varying distributions of each inflow constitution. Therefore, this approach holds promise as an embedded "Digital stable marker tracing" module in the model. [ABSTRACT FROM AUTHOR]

Frontal ablation at tidewater glaciers, which comprises iceberg calving, submarine and subaerial melting, is a key boundary condition for numerical ice sheet models but remains difficult to measure directly in-situ. Many previous studies have quantified frontal ablation over varying spatio-temporal scales, however most use ice discharge as an approximation for frontal ablation, thereby neglecting the influence of terminus location change. Frontal ablation estimates that do account for terminus location change are spatio-temporally limited by the availability of observational data. Here, we present a processing chain to quantify frontal ablation using open-source observational data. We apply the processing chain to 49 tidewater glaciers in Greenland with reliable near-terminus bathymetry data in the BedMachine V4 dataset. Nearterminus volume change over the time period 1987 - 2020 is determined using a previously published dataset of terminus positions (TermPicks), ice thicknesses from ArcticDEM and AeroDEM, adjusted for surface elevation change over time, and bathymetry data from BedMachine v4. Assuming a vertical terminus geometry and uniform ice density, we estimate frontal ablation as the difference between mass flux towards the terminus (Mankoff et al., 2020) and mass change between consecutive observation. The frontal ablation dataset offers exciting opportunities for developing new insights into ice dynamics, including helping to improve numerical model hindcasting and projections. Lastly, we provide a processing chain that may serve as a community standard for determining frontal ablation from observational data for any tidewater glacier. [ABSTRACT FROM AUTHOR]

Tremendous amounts of materials and energy are transported from the East China Sea (ECS) to the East/Japan Sea (EJS) through the Korea/Tsushima Strait (KTS). Tides undoubtedly play an important role in regulating ocean circulation on the broad continental shelf of the ECS, while the effects of tides on the water exchange between the ECS and EJS remain unclear. Using a three-dimensional Regional Oceanic Modeling System (ROMS) circulation model, we conducted numerical experiments with tides, without tides, and only barotropic tides. The results showed that the water flux across the KTS can increase by up to 13% (in summer) when excluding tides from the numerical simulation. To understand how tidal forcing regulates the KTS water flux, we performed a dynamic diagnostic analysis and revealed that the variation in sea surface height under tidal effect is the main reason for the water flux variation across the KTS. The tidal effect can adjust the sea surface height, weaken the pressure gradient and reduce the water flux across the KTS, which affect the intensity of water exchange between the ECS and EJS. The tidal effect can alter sea level difference between the Taiwan Strait and the KTS, which influences the KTS water flux. Tides can also influence the KTS water flux by altering the sea surface height through interaction with topography and stratification. We also found that tidal effect weakens the northward intrusion of the Yellow Sea Warm Current in winter and in turn enhances the water flux across the KTS according to volume conservation. These modeling results imply that tides must be considered when simulating the ocean environment of the northwestern Pacific Ocean. [ABSTRACT FROM AUTHOR]

Transplanted (T) Aman rice covers most of the arable land in the south coastal region of Bangladesh, where nitrogen fertilizer requirement in the Ganges tidal water flooded ecosystem yet not determined. The on-farm experiment was conducted at Dumki Upazila, Patuakhali district of Bangladesh, during T. Aman rice season 2020. The three replicated randomized complete block design was used in the experiment. There were eight treatments with different rates of nitrogen, e.g., control (no nitrogen fertilizer), 18, 36, 54, 72, 90, 108, and 126 kg N ha-1, which was equivalent to 0, 20, 40, 60, 80, 100, 120 and 140% of the current recommended rate, respectively. The test variety of rice was BR23. An increase in nitrogen rates progressively increased the grain yield of rice. The highest yield of 5.04 t ha-1 was found in 54 kg N ha-1 rate. However, using a quadratic equation, the most optimum rate was 75 kg N ha-1, 17% lower than the current recommendation. Nitrogen amendment could increase T. Aman rice grain yield by only 35% over control under tidal water flooded conditions. The agronomic efficiency, recovery efficiency, and physiological efficiency of nitrogen were higher in lower rates of N and gradually decreased with the increase of the rate of N application. The present study recommends 75 kg N ha-1 for cultivating T. Aman rice (BR23) in tidal water flooded the south coastal ecosystem of Bangladesh. [ABSTRACT FROM AUTHOR]

Mangrove wetlands are vulnerable coastal ecosystems that provide critical habitats for aquatic life. Tai O is a popular tourist village on Lantau Island, Hong Kong, which is surrounded by mangrove wetlands with rich biodiversity; and this village is also famous for its traditional stilt houses. However, the untreated municipal sewage from some stilt houses is directly discharged into nearby tidal channels, potentially threatening health of the adjacent mangrove wetlands. In order to evaluate the anthropogenic impact on these wetlands and identify the potential sources of their pollution, this study aimed to evaluate spatial (at the sampling points) and temporal (during weekdays and weekends) differences in the quality of their tidal water, and examine relationships between the water quality and the density of the stilt houses. The results indicated that the water quality was worse during weekends. The ammonia concentrations in most samples exceeded the limits of the Hong Kong Water Quality Objectives, China's Sea Water Quality Standards, and even the U.S. EPA criterion for fish reproduction. This high ammonia input could potentially adversely affect the mangrove ecosystem, underscoring the need for further comprehensive studies. Moreover, some of the weekend water samples had lower dissolved oxygen levels and were polluted by phosphate. Our Principal Component Analysis revealed that water quality was correlated with stilt house density, suggesting that anthropogenic inputs of untreated sewage was the major source of pollution. These findings highlight that nutrients released from human activities, particularly ammonia and phosphate, must be controlled for a better protection of mangrove wetland ecosystems. [ABSTRACT FROM AUTHOR]

Monitoring changes in glacial dynamics is essential for understanding the environmental response to a ccelerated climate warming in the Arctic. However, geodetic surveys in polar regions continue to present considerable challenges because of the harsh environmental condit ions and the polar night. This study records a 14--year--long time series (2006-2019) of GNSS surveys of the positions of 16 ablat ion stakes distributed across Hansbreen, a tidewater glacier in southern Svalbard. The measurements were conducted with an exceptionally high temporal resolution, from about one week to about one month, and covering altitudes ranging from 0 to 490 m asl. The position of one stake was surveyed every day. The primary data products consist of the stake coordinates and velocities. Time series of annual and seasonal velocities are also provided. This dataset may be a subject of further studies of glacier dynamics in relation to the long--term and seasonal impact of climate change on ice flow in the region. It also offers unique material for tuning numerical models of glacier dynamics and for validating satellite--derived products such as velocity and digital elevation models. The dataset described here has been made publicly available through the Zenodo repository: https://doi.org/10.5281/zenodo.8289380 (Błaszczyk et al., 2023). [ABSTRACT FROM AUTHOR]

The city has also been variously termed "Southeastern Virginia", and its Census Metropolitan Statistical Area (MSA) remains "Virginia Beach-Norfolk-Newport News, VA-NC, MSA." In recent decades, various institutions have increasingly adopted the "Hampton Roads" name, including those that span the individual cities, such as Hampton Roads Planning District Commission, Hampton Roads Transportation Planning Organization, and the Hampton Roads Sanitation District. In 1680, the town of Norfolk was officially named (after Norfolk, England) when the Virginia Assembly established a trading center. Norfolk, Virginia, is the host city of the 78th annual meeting of the Southeastern Division of the American Association of Geographers (SEDAAG). [Extracted from the article]

We present a novel thickness inversion approach that leverages satellite products and state-of-the-art ice flow models to produce distributed maps of sub-glacial topography consistent with the dynamic state of a given glacier. While the method can use any complexity of ice flow physics as represented in ice dynamical models, it is computationally cheap and does not require bed observations as input, enabling applications on both local and large scales. Using the mismatch between observed and modelled rates of surface elevation change (dh/dt) as the misfit functional, iterative point-wise updates to an initial guess of bed topography are made, while mismatches between observed and modelled velocities are used to simultaneously infer basal friction. The final product of the inversion is not only a map of ice thickness, but is also a fully spun-up glacier model that can be run forward without requiring any further model relaxation. Here we present the method and use an artificial ice cap built inside a numerical model to test it and conduct sensitivity experiments. Even under a range of perturbations, the method is stable and fast. We also apply the approach to the tidewater glacier Kronebreen on Svalbard and finally benchmark it on glaciers from the Ice Thickness Models Intercomparison eXperiment ITMIX, , where we find excellent performance. Ultimately, our method shown here represents a fast way of inferring ice thickness where the final output forms a consistent picture of model physics, input observations and bed topography. [ABSTRACT FROM AUTHOR]

Mangrove ecosystems in the Caribbean are frequently exposed to hurricanes, leading to structural and regenerative change that elicit calls for recovery action. For those mangroves unaffected by human modifications, recovery can occur naturally. Indeed, observable natural recovery after hurricanes is the genesis of the "disturbance adaptation" classification for mangroves; while structural legacies exist, unaltered stands often regenerate and persist. However, among the >7,000 islands, islets, and cays that make up the Caribbean archipelago, coastal alterations to support development affect mechanisms for regeneration, sediment distribution, tidal water conveyance, and intertidal mangrove transgression, imposing sometimes insurmountable barriers to natural post‐hurricane recovery. We use a case study approach to suggest that actions to facilitate recovery of mangroves on Caribbean islands (and similar settings globally) may be more effective when focusing on ameliorating pre‐existing anthropogenic stressors. Actions to clean debris, collect mangrove propagules, and plant seedlings are noble endeavors, but can be costly and fall short of achieving recovery goals in isolation without careful consideration of pre‐hurricane stress. We update a procedural framework that considers six steps to implementing "Ecological Mangrove Restoration" (EMR), and we apply them specifically to hurricane recovery. If followed, EMR may expedite actions by suggesting immediate damage assessment focused on hydrogeomorphic mangrove type, hydrology, and previous anthropogenic (or natural) influence. Application of EMR may help to improve mangrove recovery success following catastrophic storms, and reduce guesswork, delays, and monetary inefficiencies. [ABSTRACT FROM AUTHOR]

We revise and evaluate frontal ablation fluxes obtained by the Open Global Glacier Model (OGGM) for Greenland's tidewater peripheral glaciers de-coupled from the ice sheet. By making use of new region-wide ice thickness and solid ice discharge data, we re-evaluate model performance and suggest future research directions to improve the ice thickness estimation of glacier models. OGGM is unable to predict individual tidewater glacier dynamics well if it has to rely only on surface mass balance estimates and the assumption of a closed budget to constrain the calving parameterization. Velocity observations are essential to constrain the model and estimate the dynamic mass loss of Greenland's tidewater peripheral glaciers. [ABSTRACT FROM AUTHOR]

Tidewater glaciers are an important and difficult part of the cryosphere to study owing to their complex nature and often inaccessible and physically challenging environments. The interaction of glacier and fjord processes furthermore presents particular observational challenges. Modelling provides a possible solution to these issues, but, at the glacier scale, the processual complexities require a 3-D full-Stokes approach that is computationally expensive. Additionally, the lack of data for model validation or constraints imposes further obstacles. Despite this, progress on modelling such glaciers with explicit inclusion of all relevant processes is being made. The key remaining challenges are including more realistic representations of calving and coupling 3-D glacier modelling with 3-D fjord circulation modelling to allow inclusion of the effect of cross-fjord circulation. We are confident, however, that these issues can be resolved and will be resolved over the next decade. [ABSTRACT FROM AUTHOR]

Existing analyses of salt marsh carbon budgets rarely quantify carbon loss as CO2 through the air–water interface in inundated marshes. This study estimates the variability of partial pressure of CO2 (pCO2) and air–water CO2 fluxes over summer and fall of 2014 and 2015 using high‐frequency measurements of tidal water pCO2 in a salt marsh of the U.S. northeast region. Monthly mean CO2 effluxes varied in the range of 5.4–25.6 mmol m−2 marsh d−1 (monthly median: 4.8–24.7 mmol m−2 marsh d−1) during July to November from the tidal creek and tidally‐inundated vegetated platform. The source of CO2 effluxes was partitioned between the marsh and estuary using a mixing model. The monthly mean marsh‐contributed CO2 effluxes accounted for a dominant portion (69%) of total CO2 effluxes in the inundated marsh, which was 3–23% (mean 13%) of the corresponding lateral flux rate of dissolved inorganic carbon (DIC) from marsh to estuary. Photosynthesis in tidal water substantially reduced the CO2 evasion, accounting for 1–86% (mean 31%) of potential CO2 evasion and 2–26% (mean 11%) of corresponding lateral transport DIC fluxes, indicating the important role of photosynthesis in controlling the air–water CO2 evasion in the inundated salt marsh. This study demonstrates that CO2 evasion from inundated salt marshes is a significant loss term for carbon that is fixed within marshes. [ABSTRACT FROM AUTHOR]

We used a numerical model to investigate the effects of sea‐level rise (SLR) on the biogeochemical processes in the York River Estuary with extensive tidal marshes. The fully‐coupled hydrodynamic‐water quality‐marsh model accounts for the spatial and temporal variations of physical‐biogeochemical interactions between the tidal marshes and surrounding waters. This study focuses on an SLR scenario where the vertical accretion of tidal marshes keeps pace with the rising sea levels. Results show that SLR amplifies the tidal range and prolongs flooding duration, which results in enhanced porewater exchanges of materials between the tidal marshes and the surrounding waters. The increased availability of shallow‐water habitats and enhanced light utilization in the shallow areas under SLR promote phytoplankton production (PP) in the shallow‐water regions of the York River. Consequently, the organic carbon in the open water is fueled by the contributions from shallow waters and the enhanced export of organic carbon from the marshes. The change in the dissolved oxygen (DO) budget in the York River Estuary is attributed to changes in water column respiration, net metabolism of the benthic layer, reaeration, PP, and increased stratification under SLR. The net DO flux out of the York River increases at the York River mouth. Diel DO variation, especially in the marshes in the upper estuary, promotes phosphorus release from the sediment. The changes in dissolved nitrogen under SLR are relatively minimal. Plain Language Summary: As one of the consequences of climate change, sea‐level rise (SLR) has a wide‐ranging impact on the estuarine environment. SLR has a significant impact on tidal marshes, which are located at the interface between estuarine water and inner land. Despite the possibility of marsh retreat, many tidal marshes will keep up with the SLR through vertical accretion if sufficient sediment sources are available. SLR will result in deeper water and elevated tidal marshes in the estuary. The biogeochemical processes under this condition were predicted using a numerical modeling approach in this study. The tidal range is estimated to increase, encouraging more material exchange between marshes and estuarine water. More organic carbon is produced in this system, resulting in increased oxygen consumption. In this condition, there is a greater likelihood of low‐DO events occurring during the diel cycle, which will further affect nutrient dynamics. Key Points: A coupled tidal marsh and eutrophication model is applied to study the impacts of sea‐level rise (SLR) on estuarine biogeochemical processesThe tidal marshes that keep up with SLR are predicted to have more porewater‐surface water exchange and dissolved material exportsThe York River Estuary is predicted to have lower bottom dissolved oxygen and more hypoxia events under SLR [ABSTRACT FROM AUTHOR]