Coastal Ecosystem Health Research Articles

Place-Based Conservation in Coastal and Marine Ecosystems: The Importance of Engagement with Underrepresented Communities

Through the years, research has described the importance of community-based approaches in the management of coastal and marine ecosystems. Coastal and marine issues are multifaceted and require place-specific approaches developed in partnership with vulnerable communities who are impacted by environmental stressors. Place-based conservation, a management approach that focuses on unique, place-specific characteristics, and other similar methods. It considers the need to integrate human dimensions and location-centered approaches, which are often lacking in typical natural resource management. Meaningful engagement with underrepresented communities can holistically account for socioeconomic factors and cultural knowledge that inform best management practices. As the health of marine and coastal ecosystems is linked with environmental quality and local livelihoods, engaging practitioners with knowledge of these systems can support science and trust in environmental management. This article discusses the importance of community-based research, local insight, various examples of successful management, and culturally relevant knowledge to advance sustainable place-based conservation.

Rapid diagnosis of the geospatial distribution of intertidal macroalgae using large-scale UAVs

Macroalgae have been used as indicators of the health of coastal ecosystems, they function as sinks of CO2 and are essential contributors to primary production. With the increase in anthropogenic activities, it is crucial to assess the impact of such activities on these ecosystems. As traditional surveying techniques, although accurate, are time-consuming and their area coverage is limited, novel techniques are required to monitor the coverage and diversity of intertidal macroalgae. We propose a methodology using the free-source Semi-Automatic Classification Plugin from QGIS to use UAV and multispectral cameras for the spatiotemporal monitoring of intertidal macroalgae. We also compared the performance of six classifiers: Minimum Distance (MD), Maximum Likelihood (ML), Spectral Angle Mapping (SAM), Multi-Layer Perceptron (MLP), Random Forest (RF) and Support Vector Machine (SVM), for three types of macroalgae classification: general, taxonomical groups and species. As proof of concept, an intertidal rocky shore in a marine protected area (NW Spain) was studied for four months. RF and SVM achieved similar results, with both being recommended for the general (OASVM = 97.4±1.7 and OARF = 98.3±1.7) and taxonomical groups (OASVM = 91.6±1.9 and OARF = 89.2±4.5). SVM and ML were found to be more suitable for species classification (OASVM = 77.4±11.4 and OAML = 74.2±9.7). SAM and MLP provided the least performant species classifiers because of the overlap in the macroalgae spectral signatures. The plugin showed limitations when tuning the input parameters of the MLP classifier and did not let to add a validation dataset. Additionally, we present an open-access GIS web application, Alganat 2000 GIS web, to facilitate the monitoring and management of coastal areas. We conclude that the proposed methodology using the SVM or ML classifiers is an effective tool for assessing intertidal macroalgal assemblages. Its easy and rapid implementation is beneficial for researchers who are not very familiar with coding and machine learning frameworks and reduces the time and cost of fieldwork. As future work, we propose the combination of the multispectral bands with topographic and spectral indices and to research the application of deep learning models to the classification of intertidal macroalgae.

Anthropogenic and climate change-driven coastline dynamics will erode future nesting habitats of the kentish plover on the central adriatic coast

Shorebirds play a crucial role in assessing the health of coastal ecosystems due to their life history, behaviour, migratory patterns, and feeding preferences. Many shorebird species are experiencing population declines worldwide, driven by habitat loss and climate change. Understanding these challenges requires extensive data on their distribution and breeding ecology. The Kentish Plover (Anarhynchus alexandrinus) is a small shorebird that constructs its nests on sandy beaches. However, there is a scarcity of data regarding the reproductive ecology of this species in many areas, including the Molise region of Southern Italy. This study aimed at assessing the potential role of environmental variables derived from remote sensing to model current and future Kentish Plover nesting habitat suitability accounting for future scenarios of coastal dynamics in 2040. Data on Kentish Plover nests were collected along the Molise coast over several years and used to calibrate ecological niche models (ENMs) relying on environmental variables derived from coastal images. Kentish Plover nesting habitat suitability was mostly affected by distance from open sand, artificial surfaces, shoreline, and herbaceous vegetation and forested areas. The study predicts an average decline of more than 22% in suitable nesting environments for the Kentish Plover within the next two decades. Results indicated that our modelling approach can offer valuable insights for the conservation strategy of Kentish Plover in the region. In conclusion, we assert that preserving the nesting habitat of the Kentish Plover will not only safeguard this species, but also other species that inhabit similar environments, along with providing protection for coastal landscapes and associated ecosystem services.

Assessment of anthropogenic particles in Holothuria sanctori from Tenerife (Canary Islands, Spain)

Sea cucumbers play a key role in maintaining the health of coastal marine ecosystems. The aim of this research was to evaluate the presence of anthropogenic particles in sea cucumbers of the species Holothuria sanctori in intertidal pools from Tenerife (Canary Islands, Spain) and in the surrounding seawater. In the case of sea cucumbers (n = 18), the gastrointestinal tract (particles ingested directly from the sediment) and Cuvierian tubules (particles presence as a result of gas exchange with seawater) were analysed separately. Anthropogenic particles were found in all samples, with an average concentration of 20.0 ± 4.4 items per litre in seawater and 11.8 ± 3.9 items per individual in the sea cucumbers, with a higher concentration of particles in the gastrointestinal tract (9.3 ± 3.4 items per gastrointestinal tract) than in the Cuvierian tubules (2.6 ± 3.3 items per Cuvierian tubules). Transparent and blue microfibres were predominant, accounting for over 90 % of the samples analysed. A significant proportion of these fibres were of cellulosic origin (either natural or semisynthetic, comprising 78.7 %), while fully synthetic polymers (microplastics), were also identified, including polyester and polyvinyl chloride (the latter exclusively detected in seawater).

Influence of Rivers, Tides, and Tidal Wetlands on Estuarine Carbonate System Dynamics

Variations in estuarine carbonate chemistry can have critical impacts on marine calcifying organisms, yet the drivers of this variability are difficult to quantify from observations alone, due to the strong spatiotemporal variability of these systems. Terrestrial runoff and wetland processes vary year to year based on local precipitation, and estuarine processes are often strongly modulated by tides. In this study, a 3D-coupled hydrodynamic-biogeochemical model is used to quantify the controls on the carbonate system of a coastal plain estuary, specifically the York River estuary. Experiments were conducted both with and without tidal wetlands. Results show that on average, wetlands account for 20–30% of total alkalinity (TA) and dissolved inorganic carbon (DIC) fluxes into the estuary, and double-estuarine CO2 outgassing. Strong quasi-monthly variability is driven by the tides and causes fluctuations between net heterotrophy and net autotrophy. On longer time scales, model results show that in wetter years, lower light availability decreases primary production relative to biological respiration (i.e., greater net heterotrophy) resulting in substantial increases in CO2 outgassing. Additionally, in wetter years, advective exports of DIC and TA to the Chesapeake Bay increase by a factor of three to four, resulting in lower concentrations of DIC and TA within the estuary. Quantifying the impacts of these complex drivers is not only essential for a better understanding of coastal carbon and alkalinity cycling, but also leads to an improved assessment of the health and functioning of coastal ecosystems both in the present day and under future climate change.

Inhibitory Effect of Combined Exposure to Copper Ions and Polystyrene Microplastics on the Growth of Skeletonema costatum

As two significant pollutants, the increased concentrations of copper ions and microplastics in coastal waters pose a substantial threat to the health of marine ecosystems. This study explored the individual and combined toxic effects of copper ions and microplastics on the marine diatom Skeletonema costatum. The results indicated that copper ions at a concentration of 0.05 mg/L exerted a negative impact on the growth of S. costatum; however, the influence of microplastics on algal cell growth was more complex: there was no significant inhibition of algal cell growth observed within the first 72 h of cultivation, but a pronounced negative effect on cell growth was noted between 72 and 96 h, with high concentrations (10.00 mg/L) of microplastics even causing a premature stagnation phase in algal cell growth. When both pollutants were present simultaneously, their impact on cell growth was similar to that of the microplastic pollution group, yet the growth condition was better than that of the copper ion pollution group. Through investigation of adsorption rates and toxicity mitigation rates, it was found that the adsorption of copper ions by microplastics was a significant reason for the improved growth condition of algal cells in the mixed pollution group compared to the copper ion pollution group. However, in the later stages of cultivation, the inhibitory effect of microspheres on algal cell growth counteracted their mitigating effect on copper ion toxicity. This study provides a reference for evaluating the impact of microplastics and heavy metals on coastal ecosystem health and for revealing the interactions between different pollutants.

Techno-economic assessment and transient modeling of a solar-based multi-generation system for sustainable/clean coastal urban development

To ensure the health of vulnerable coastal ecosystems, a transition to sustainable energy solutions is essential. Environmentally friendly systems powered by renewable sources offer not only a reduction in pollution but also the adaptability needed for a flexible and resilient energy future. This study proposes and comprehensively evaluates an integrated solar-based system designed to meet the daily needs of coastal cities. The proposed system incorporates key components such as dual-loop power cycles, parabolic trough solar collectors, liquefied natural gas (LNG) regasification, reverse osmosis, and proton exchange membrane electrolysis. To optimize energy utilization, the inclusion of a thermoelectric generator (TEG) is considered, harnessing the thermal gradient among the LNG stream and the power cycle fluid. We conduct transient modeling, incorporating comprehensive scenarios that account for both thermal and economic aspects. The performance evaluation of the system focuses specifically on coastal regions, with San Francisco serving as a case study. The dynamic simulation results demonstrate the capability of the integrated system in fulfilling the urban needs for one year, delivering 1,134,207 cubic meters of potable water and generating 11,306 MWh of electricity. Financial analysis reveals that the solar unit accounts for over 46 % of the total cost, with an hourly cost rate of $69.61. The levelized cost of electricity is predicted at 4.61 cents/kWh, while the levelized cost of water is calculated at 30.54 cents/m3. These findings provide valuable insights into the cost-effectiveness and competitive advantage of the system in terms of energy and water production.

Assessment of Coastal Carbon Storage and Analysis of Its Driving Factors: A Case Study of Jiaozhou Bay, China

Global climate change and coastal urbanization have significantly impacted the health and carbon storage of coastal zone ecosystems. Investigating the spatial and temporal variations in coastal carbon storage is crucial for developing effective strategies for land management and ecological protection. Current methods for evaluating carbon storage are hindered by insufficient accuracy and data acquisition challenges, necessitating solutions to enhance both reliability and precision. This study aims to assess the variations in carbon storage and annual carbon sequestration in the Jiaozhou Bay coastal zone from 1990 to 2020 and to identify the driving factors by integrating the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) and Carnegie Ames Stanford Approach (CASA) models with remote sensing data and geographic detector methods. The findings suggest that Jiaozhou Bay has experienced a substantial decrease in carbon storage, declining by 17.4% from 1990 to 2020, and annual carbon sequestration, decreasing by 35.5% from 1990 to 2016, but has stabilized recently. Vegetation cover and water bodies play critical roles in regional carbon storage. Furthermore, the dynamics of carbon storage and land use patterns are significantly influenced by socioeconomic factors, including GDP and population density. A comparison of the InVEST and CASA models demonstrates consistency in their carbon storage and annual carbon sequestration assessments. Combining these models in future assessments can enhance the scientific rigor and accuracy of the research, providing more reliable evidence for ecosystem management and policy making.

Differential toxic effects of nano-titanium dioxide on clams (Meretrix meretrix) with various individuality

Nano-TiO2 is inevitably released into aquatic environment with increasing of nanotechnology industries. Study pointed that different individuality showed divergent behavioral and physiological response when facing environmental stress. However, the effects of nano-TiO2 on tolerance of bivalves with different individualities remain unknown. In the study, clams were divided into two types of individuality - proactive and reactive by post-stress recovery method. It turned out that proactive individuals had quicker shell opening level, stronger burrowing behavior, faster feeding recovery, higher standard metabolic rate and more rapid ammonia excretion ability than reactive individuals after exposed to air. Then, the survival rate, hemocytes response and oxidase activity of classified clams were evaluated after nano-TiO2 exposure. Results showed that after 30 d exposure, proactive individuals accelerated burrowing behavior with higher survival rate. Moreover, proactive clams had better adaptability and less hemocytes response and oxidative damage than reactive clams. The study highlights the individualities of marine shell fish determine individual capacity to adapt to environmental changes, play important roles in aquaculture and coastal ecosystem health.

Conservation efforts mitigate effects of human disturbance on ghost crab (Ocypode macrocera) abundance and behavior on a sandy beach in Kuakata, Bangladesh

Protected areas play a crucial role in promoting and conserving species by providing a sanctuary for wildlife and natural habitats. In coastal regions, safeguarding measures become even more significant due to the unique challenges posed by anthropogenic activities. This study focuses on the impact of human activities on beach-dwelling biota, specifically the ghost crab (Ocypode macrocera), and highlights the importance of establishing protected areas to safeguard biodiversity and counteract negative impacts on coastal ecosystems. The study was conducted in Kuakata, the coastal region in Bangladesh, known for its ghost crab population. By comparing protected with non-protected beaches, the study examines the effects of protection status on ghost crab abundance and burrow characteristics. Field observations and data collection reveal that protected beaches harbor a greater abundance of ghost crabs compared to non-protected beaches. However, while protection status significantly improves crab abundance, it does not necessarily increase the mean burrow opening size. Interestingly, protected areas show a higher number of small burrow sizes, indicating that protected beaches not only act as feeding grounds but also serve as breeding and nursery grounds for ghost crabs. These findings illustrate the multifaceted role protected areas play in supporting the entire life cycle of ghost crabs, and underscore the importance of preserving these habitats for the species' long-term survival. It highlights the importance of effective management and conservation measures to preserve the health and integrity of coastal ecosystems. By establishing and managing protected areas appropriately, we can ensure the continued existence and viability of these invaluable habitats. Specific human activities that harm coastal biodiversity can be identified to develop targeted conservation strategies. Through this study, such strategies can be developed which may include measures like restricting beach access during breeding season or implementing sustainable tourism practices to lessen the impact.

Assessment of coastal pollutants and health status of Pacific oysters (Magallana gigas) in the Bahía Blanca Estuary and adjacent beaches (Argentina)

This study assessed the effects of pollutants on Magallana gigas along a coastal zone with different levels of human activity: a highly impacted zone in the Bahía Blanca Estuary and a less impacted zone on the adjacent sandy beaches. Oysters collected in 2021 were analyzed for various factors, including metals, polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, microplastics, oxidative stress and histology. Oysters of both environments exhibited detectable concentrations of all these pollutants in their tissues. However, the estuarine oysters showed higher concentrations of Zn, Cu and As and total PAHs than the beach oysters. Banned organochlorine pesticides were detected only in beach oysters. Estuarine oysters displayed morphological changes in their digestive gland including a reduction in the mean epithelial thickness of the tubule and elevated lipid peroxidation levels, indicating cellular damage. This study underscores the widespread presence of pollutants in M. gigas, indicating the need for effective strategies to safeguard coastal ecosystem health.

Exploring the Microbial Mosaic: Insights into Composition, Diversity, and Environmental Drivers in the Pearl River Estuary Sediments.

River estuaries are dynamic and complex ecosystems influenced by various natural processes, including climatic fluctuations and anthropogenic activities. The Pearl River Estuary (PRE), one of the largest in China, receives significant land-based pollutants due to its proximity to densely populated areas and urban development. This study aimed to characterize the composition, diversity, and distribution patterns of sediment microbial communities (bacteria, archaea, and eukaryotes) and investigated the connection with environmental parameters within the PRE and adjacent shelf. Physicochemical conditions, such as oxygen levels, nitrogen compounds, and carbon content, were analyzed. The study found that the microbial community structure was mainly influenced by site location and core depth, which explained approximately 67% of the variation in each kingdom. Sites and core depths varied in sediment properties such as organic matter content and redox conditions, leading to distinct microbial groups associated with specific chemical properties of the sediment, notably C/N ratio and NH4+ concentration. Despite these differences, certain dominant taxonomic groups were consistently present across all sites: Gammaproteobacteria in bacteria; Bathyarchaeia, Nitrososphaeria, and Thermoplasmata in archaea; and SAR in Eukaryota. The community diversity index was the highest in the bacteria kingdom, while the lowest values were observed at site P03 across the three kingdoms and were significantly different from all other sites. Overall, this study highlights the effect of depth, core depth, and chemical properties on sediment microbiota composition. The sensitivity and dynamism of the microbiota, along with the possibility of identifying specific markers for changes in environmental conditions, is valuable for managing and preserving the health of estuaries and coastal ecosystems.

The silent threat of plastics along the coastal frontiers of Bangladesh: Are we concerned enough?

Globally plastic pollution is posing a significant threat to the health and integrity of coastal ecosystems. This study aimed to provide a comprehensive overview of plastic pollution in the coastal areas of Bangladesh by examining land-based macroplastic distribution, exploring microplastic (MP) contamination in the coastal aquatic ecosystem and enhancing our understanding of the potential risks associated with MP contamination. Citizen science based monitoring approach using the android application was applied to understand the land-based plastic pollution in the coastal area of Bangladesh. From December 2022 to December 2023, a total of about 3600 photographs of plastic items from 215 citizen scientists were received from the coastal area of Bangladesh covering 580 km long coast line. Polymer Hazard Index (PHI) and Pollution Load Index (PLI) were also calculated to understand the risk of plastic pollution in sediment, water, aquatic organism, dried fish and sea salt. A total of 43 land-based plastic items reported from the coastal area of Bangladesh. Among these plastic items single use items contributed 58.2 % while disposable plastic items contributed 41.8 %. A strong spatial variability in the distribution of these plastic items was observed. PHI and PLI values suggested hazard category-I for MP contamination in sediment, sea salt, water, commercial fishery resources and dry fish. This study highlighted that coastal land area, sea salt, dried fish, water, sediment and organisms are contaminated with plastics which might have the potential threats to human health. Findings from this study will serve as reference data and also baseline for future research to combat the plastic pollution.

Integration of socio-ecological data to prioritize biodiversity hot-spots for Marine Protected Area (MPA) delineation in the coastal zone of Bangladesh

Marine Protected Areas (MPAs) are widely used tools for conserving coastal and marine biodiversity and ecosystem health. However, the goal of declaring and managing at least 10 % of coastal and marine waters as MPAs has not been achieved in Bangladesh and many other countries. This study aimed at prioritizing the potential areas for MPA delineation in the south-west coastal zone of Bangladesh. The study also examined the socio-economic status, environmental and ecological characteristics of the study areas. Data on socio-economic, environmental, ecological, and management variables were collected through intensive field surveys from August 2023 to December 2023. The data were integrated using a multi-criteria analytical technique. Fishing was identified as the primary occupation for all fishermen surveyed, with secondary occupations including fish selling, marketing, and drying activities. The fishing areas for fishermen from the three survey sites were mainly concentrated in the offshore area. All three areas were identified as biodiversity hotspots, with Kuakata coast showing the highest species diversity, followed by Salimpur and Sandwip coasts. The study revealed that the Kuakata coast has the highest conservation importance, especially for IUCN red-listed species, juvenile fisheries species, and megafauna species. Salimpur coast is important for the conservation of saltmarshes, mangroves, and their dependent communities, while Sandwip is crucial for juvenile fish species conservation. Based on socio-ecological criteria, Kuakata was recommended as the most potential site for MPA delineation, followed by Salimpur and Sandwip. Implementing these recommendations can improve the management and execution of existing MPAs by focusing conservation efforts on areas with the highest biodiversity and ecological importance, ensuring better protection for vulnerable species, and enhancing the sustainability of local fishing communities. This, in turn, will ultimately enhance biodiversity conservation and ecosystem health in the southwest coastal area of Bangladesh.

Biomass distribution patterns of salt marshes: A detailed spatial analysis in central China's coastal wetlands

Wetland vegetation plays a critical role in the health of coastal ecosystems, serving pivotal roles in disaster mitigation and blue carbon sequestration. While extensive research on the effects of sea-level rise on the aboveground biomass of salt marsh vegetation, the spatial patterns of biomass distribution related to surface elevation remain less explored. This study investigates the growth patterns and spatial distribution of Spartina alterniflora in central coast of China through field surveys and the analysis of remote sensing data via Google Earth Engine. We have found a significant parabolic relationship between vegetation biomass and distance from the sea, with the optimal biomass influenced by the location of the marsh front edge. Further, we observe that biomass distribution varies with surface elevation and is influenced by geomorphological features notably creeks, which introduce significant elevation differences and local biomass fluctuations. These findings offer new insights into the spatial distribution of tidal flat vegetation, which are vital for effective coastal management and for modeling the evolution of tidal flats.

The assessment of chlorophyll-a retrieval algorithm and its spatial-temporal distribution using sentinel-2 MSI off the Banjir Kanal Timur River, Semarang, Indonesia

In aquatic ecology, Chlorophyll-a (Chl-a) plays a pivotal role in biogeochemical cycles, as well as a key indicator for the trophic state in the environment. Coastal area of Semarang is known as eutrophic waters. Thus continuous monitoring of Chl-a will be beneficial for the management of the impact of the trophic dynamic in the coastal waters of Semarang. Taking the benefit of the continuous monitoring of satellite measurement, the present study provides the assessment of Chl-a off the Banjir Kanal Timur (BKT) River, Semarang, using the proper remote sensing approach. In this study, algorithms were generated according to bands sensitive to Chl-a scattering properties, using multiple regression between in-situ Chl-a and Bottom of Atmospheric (BoA) reflectance from Sentinel-2 with 10 m resolution. A total of 43 water samples were collected to build the algorithm and 43 of the water samples were used for validation during the passing time of Sentinel-2 at the equator i.e., on 21 August 2021 at 9.00–11.00 local time. The results show that the performance of the algorithm generated in this study has high accuracy as denoted by the low RMSE, and MAPE, respectively. For the seasonal variation, the highest (lowest) concentration of Chl-a is observed in December (September), with values reaching 11.92 µg/L (7.06 µg/L). The seasonal fluctuation of Chl-a depends on air temperature and sunshine duration. High (low) air temperature and long (short) duration of solar exposure result in increased (decreased) Chl-a off the BKT River. Conversely, the elevated wind velocity only impacts the rise of Chl-a in the region far from the river estuary, which is associated with the mixing process. BKT waters are categorized as eutrophic conditions, with a concentration exceeding 6 µg/L. These algorithms can provide valuable insights into the health and productivity of coastal ecosystems, aiding in their monitoring and management.

Differential effects of warming on the complexity and stability of the microbial network in Phragmites australis and Spartina alterniflora wetlands in Yancheng, Jiangsu Province, China.

The impact of climate warming on soil microbial communities can significantly influence the global carbon cycle. Coastal wetlands, in particular, are susceptible to changes in soil microbial community structure due to climate warming and the presence of invasive plant species. However, there is limited knowledge about how native and invasive plant wetland soil microbes differ in their response to warming. In this study, we investigated the temporal dynamics of soil microbes (prokaryotes and fungi) under experimental warming in two coastal wetlands dominated by native Phragmites australis (P. australis) and invasive Spartina alterniflora (S. alterniflora). Our research indicated that short-term warming had minimal effects on microbial abundance, diversity, and composition. However, it did accelerate the succession of soil microbial communities, with potentially greater impacts on fungi than prokaryotes. Furthermore, in the S. alterniflora wetland, experimental warming notably increased the complexity and connectivity of the microbial networks. While in the P. australis wetland, it decreased these factors. Analysis of robustness showed that experimental warming stabilized the co-occurrence network of the microbial community in the P. australis wetland, but destabilized it in the S. alterniflora wetland. Additionally, the functional prediction analysis using the Faprotax and FunGuild databases revealed that the S. alterniflora wetland had a higher proportion of saprotrophic fungi and prokaryotic OTUs involved in carbon degradation (p < 0.05). With warming treatments, there was an increasing trend in the proportion of prokaryotic OTUs involved in carbon degradation, particularly in the S. alterniflora wetland. Therefore, it is crucial to protect native P. australis wetlands from S. alterniflora invasion to mitigate carbon emissions and preserve the health of coastal wetland ecosystems under future climate warming in China.

Growing coastal tourism: Can biomonitoring provide insights into the health of coastal ecosystems?

Coastal tourism's surge raises concerns for Morocco's Agadir marine environment, notably with Taghazout Bay's impact. Our study assesses Taghazout's health, employing a comprehensive approach. Our study evaluates Taghazout's health, adopting a comprehensive approach covering physicochemical, microbiological aspects, macrobenthic fauna, metal pollution, and biomarkers in D. trunculus mollusks. Seawater quality aligns with Moroccan standards, indicating good bathing water. The intertidal zone hosts ten species, dominated by D. trunculus. Biomarker responses in D. trunculus suggest chemical stress. Land-use maps expose significant changes driven by the Taghazout Bay project, impacting approximately 37.99 % of the landscape. Construction activities notably encroached upon the Arganeraie and the coastal zone, creating a stark contrast from 2003. These findings form a crucial database for future studies, contributing significantly to environmental management and sustainable development, aiding informed decision-making and effective coastal ecosystem preservation strategies.

Human intervention caused massive destruction of the second largest mangrove forest, Chakaria Sundarbans, Bangladesh.

Mangroves provide essential ecosystem services including coastal protection by acting as coastal greenbelts; however, human-driven anthropogenic activities altered their existence and ecosystem functions worldwide. In this study, the successive degradation of the second largest mangrove forest, Chakaria Sundarbans situated at the northern Bay of Bengal part of Bangladesh was assessed using remote sensing approaches. A total of five multi-temporal Landsat satellite imageries were collected and used to observe the land use land cover (LULC) changes over the time periods for the years 1972, 1990, 2000, 2010, and 2020. Further, the supervised classification technique with the help of support vector machine (SVM) algorithm in ArcGIS 10.8 was used to process images. Our results revealed a drastic change of Chakaria Sundarbans mangrove forest, that the images of 1972 were comprised of mudflat, waterbody, and mangroves, while the images of 1990, 2000, 2010, and 2020 were classified as waterbody, mangrove, saltpan, and shrimp farm. Most importantly, mangrove forest was the largest covering areaa total of 64.2% in 1972, but gradually decreased to 12.7%, 6.4%, 1.9%, and 4.6% for the years 1990, 2000, 2010, and 2020, respectively. Interestingly, the rate of mangrove forest areadegradation was similar to the net increase of saltpan and shrimp farms. The kappa coefficients of classified images were 0.83, 0.87, 0.80, 0.87, and 0.91 with the overall accuracy of 88.9%, 90%, 85%, 90%, and 93.3% for the years 1972, 1990, 2000, 2010, and 2020, respectively. By analyzing normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), and transformed difference vegetation index (TDVI), our results validated that green vegetated area was decreased alarmingly with time in this study area. This destruction was mainly related to active human-driven anthropogenic activities, particularly creating embankments for fish farms or salt productions, and cutting for collection of wood as well. Together all, our results provide clear evidence of active anthropogenic stress on coastal ecosystem health by altering mangrove forest to saltpan and shrimp farm saying goodbye to the second largest mangrove forest in one of the coastal areas of the Bay of Bengal, Bangladesh.

Characterizing longshore transport potential and divergence of drift to inform beach loss trends

Beach loss is a growing global challenge that threatens the safety of coastal communities, the health of coastal ecosystems, recreational amenities, and regional economies dependent on tourism. Spatial gradients in longshore sediment transport, or divergence of drift (DoD), is a primary driver of beach width change over multi-annual time scales, but the response of any particular beach can be challenging to characterize and predict. Here we present a new method to characterize DoD using a non-uniform segmentation of the coastline informed by the spatial distribution of longshore transport potential, including the location of physical barriers identified using satellite imagery, and both maxima and reversals in longshore transport potential derived from nearshore wave data. The method demonstrates improved capacity to predict beach width trends at sandy beaches compared to methods that rely on a uniform segmentation of the coastline. In an application to southern California where satellite data documents two decades of beach width change, the non-uniform segmentation method correctly predicts the sign of beach trends at 93% of transects within a littoral cell and achieves a linear correlation between DoD and beach width trends exceeding 0.8. Moreover, we find that a minimum of five years of data are required to establish consistently strong correlations between DoD and beach width changes. Conversely, use of a uniform segmentation is shown to be unreliable for estimating beach width trends due to strong sensitivities to shoreline segment size. This work shows the potential to leverage nearshore wave data and satellite-based beach width data for improved characterization of shoreline dynamics relevant to beach erosion management.