Coastal Environmental Changes Research Articles

Landcover-based detection of rapid impacts of extreme storm on coastal landscape

On September 24, 2022, Post-Tropical Hurricane Fiona made landfall in Atlantic Canada and caused unprecedented damages to the coastal communities and ecosystems therein. The aftermath triggered local government and communities in Prince Edward Island (PEI), Canada to rethink current policies and practices for coastal protection in the context of climate change. This historic hazard represents the escalating frequency and intensity of extreme weather events that globally threaten coastal regions, accelerating coastal erosion and endangering communities. This study employs landcover-based detection to assess rapid storm impact of Fiona on coastline of PEI using Sentinel-2 satellite images, to gauge the efficacy of landcover-based detection and quantify storm-induced coastal environmental changes. Our results indicate that, following Fiona, over 51 km2 coastal land loss due to the erosion at beach foreshore and inundation at tidal flat, and over 11 km2 sand dune loss mainly on the PEI north shore. This constitutes a 3.5 % loss of coastal land resources within the 1798 km2 PEI coastal zone. Fiona also caused over 194 km2 area in coastal buffer zone showed temporal fluid-mud from the eroded sediments of sand dunes, cliffs, and tidal flats, suggesting the significant sediment loss from vertical structures in addition to the direct retreat. The landcover-based method can be regarded as a valuable tool for the storm impacts on coastal environments. Based on the coastal change pattern, more sustainable coastal protection and adaptation measures should be developed, focusing on reducing hydrodynamic intensity and improving erosion capacity, with consideration of the increasing likelihood of more intense and frequent storm events in a warming climate.

The Shore as a Politicized Space for Community Heritage: The Case of Pra’, Genoa

Changes in coastal and maritime environments, increasingly caused by the climate crisis and large infrastructural projects such as global port construction, significantly impact community identity. When a community’s terraqueous space – a space that transcends the land-sea binary distinction – suffers a shock, long-term sociability within the community and relationships with nature are altered. This article connects the challenges of coastal community spaces and the community’s cultural heritage by articulating a critical ontology of the shore. The connection is illustrated using the example of Pra’ in Genoa, where constructing a large port terminal has detached the local maritime community from the sea.

MAXIMUM LIKELIHOOD ALGORITHM DETECTS COASTAL WETLAND CHANGES IN TWO CONTRASTING COASTAL WETLANDS IN LOUISIANA

Abstract. Louisiana coastal wetlands contain about 37 percent of the estuarine herbaceous marshes in the conterminous United States. However, the combined effect of sea level rise and other anthropogenic factors have altered land use land cover over the last few years. This is true for two wetlands in coastal Louisiana, Barataria bay and Wax Lake delta. Barataria Bay, Louisiana, USA has experienced significant land loss. Updated information on the dynamics of change in these wetlands is limited and poorly documented. This information is necessary to develop strategies that will contribute to reversing and halting degradation. Thus, this study employed the Maximum Likelihood classifier on Landsat satellite imagery to assess land use and land cover changes in Barataria Bay and Wax Lake Delta, southeastern Louisiana, USA. The analysis revealed notable alterations in the land cover patterns over the study period. In Barataria Bay, there was a decrease in salt marsh areas with a corresponding increase in open water and Built-up area. In contrast, Wax Lake Delta demonstrated substantial land/wetland growth, with significant expansion of vegetation cover. The Maximum Likelihood classifier demonstrated high accuracy in classifying the land cover types, with an overall accuracy of 86% for Barataria Bay and 92% for Wax Lake Delta. These results highlight the effectiveness of the classifier in accurately identifying and mapping land cover changes in coastal environments. The findings contribute valuable insights for understanding the dynamics of coastal ecosystems and can inform decision-making processes for coastal management and conservation efforts.

MONTE CARLO SIMULATION OF BARRIER-ISLAND SYSTEMS AND TSUNAMI HAZARDS

Robust characterization of the future tsunami hazard is critically important for resilient planning and engineering in coastal communities prone to tsunami inundation. The hazard from earthquake-generated tsunami waves is not only determined by the earthquake's characteristics and distance to the earthquake area, but also by the geomorphology of the nearshore and onshore areas, which can change over time. In coastal hazard assessments, a changing coastal environment is commonly taken into account by increasing the sea-level to projected values (static). However, sea-level changes and other climate-change impacts influence the entire coastal system causing morphological change (dynamic). Here, we present the modeling framework and results initially published in Weiss et al. (2022), which employs within a Monte Carlo framework the barrier island-marsh, lagoon- marsh evolution model of Lorenzo-Trueba and Mariotti (2017) and the tsunami model Geoclaw (e.g., LeVeque et al. 2011). We compare the runup of the same suite of earthquake-generated tsunamis to a barrier system for statically adjusted and dynamically adjusted sea level and bathymetry over the period from 2000 to 2100. We employ Representative Concentration Pathways 2.6 and 8.5 without and with treatment of Antarctic ice-sheet processes (e.g., Kopp et al. 2017) as different sea-level projections.

Drivers of suspended sediment dynamics along the shorelines of the Yellow River Delta detected from satellite data

AbstractTotal suspended solids (TSS) can be a useful indicator of environmental change in nearshore coastal environments. Understanding the mechanisms of TSS variations in response to environmental drivers is of broad interest for ecology and geomorphology. The Yellow River Delta (YRD) in China is a fragile coastal region that has been affected by human activities and climate change. Here, we investigated TSS along the YRD shoreline over two decades with time‐series satellite data (2002–2020). We observed that TSS concentration decreased significantly in nearshore waters (5‐m isobath) surrounding the YRD, especially in the LaiZhou Bay. During the same time period, wave height (WH) along the deltaic shoreline and sediment load from the Yellow River have decreased, while sea surface height (SSH) has displayed a positive trend. Our results indicate that WH and SSH play a major role in sediment resuspension and dispersion, while the YSD mildly affected TSS variability along the coast. Monthly bed shear stress triggered by waves was then computed using WH, wave period (WP), and SSH. Bed shear stress and TSS displayed a positive correlation. We concluded that seasonal oscillations in SSH in conjunction with wind waves are responsible for TSS variability in the shallow waters in front of the YRD.

Benthic foraminifera as proxies for assessing the effects of a pier marina construction: A case study in the naturally stressed environment of the Saco da Ribeira (Flamengo Bay, SE Brazil)

Brazilian coastal areas have been exposed to various anthropic influences including physical alteration such as marina construction. To assess the impact of the pier marina construction in the Saco da Ribeira cove (Flamengo Bay, SE Brazil), sedimentological (grain size), geochemical (organic and trace elements) parameters and benthic foraminifera were analyzed on a 50-cm-long dated sediment core covering the last century. The multiproxy approach applied to a numerical hydrodynamic model shows that the circulation in the study area underwent an overall reduction (ca. 30 %) after the pier marina construction in the 1970s, promoting an increase of mud accumulation and higher concentrations of total organic carbon and trace elements (i.e., Enrichment Factor Cu from 0.80 to 1.4) as well as a shift in the benthic foraminiferal assemblages (i.e., foraminiferal density from 63 to 23.20 specimens per 10 cm3 and dominance from 0.13 to 0.73). On the basis of these integrated data, better environmental conditions occurred before the 1970s, then an overall increase in environmental stress took place after the pier's marina construction. Our results provide a baseline for future biomonitoring projects in a stressed region and exemplify the strong capability and reliability of benthic foraminifera as bioindicators of paleoenvironmental changes in coastal environments and for understanding how human pressure might induce such changes.

Mapping the impacts of coastal erosion on the heritage assets of Ynys Enlli (Bardsey Island), North Wales, UK

Coastal erosion and sea level rise has become a significant threat to coastal heritage due to climate change. Management bodies are monitoring the risks posed by undertaking studies, ranging from Rapid Coastal Zone Assessments to much larger government and research council funded studies. These studies have incorporated varying techniques and datasets such as environmental sampling, LiDAR, GPS, and UAV surveys. However, these approaches rarely combine study of historic shoreline change with physical susceptibility modeling. This paper presents a combined methodology, utilizing LiDAR and survey data collected by the Climate, Heritage, Environments of Reefs, Islands and Headlands (CHERISH) project, along with historic mapping and aerial photography to produce a risk assessment for the heritage assets located on Ynys Enlli (Bardsey Island), North Wales. By constructing an Historic Erosion Model and an Erosion Susceptibility Model using ESRI’s ArcGIS 10.5.1. with the DSAS Plugin and combining them with the LiDAR-derived spatial extents of archaeological features on the island, this project has shown that using both methodologies alongside each other can create a more complete overview of coastal environment change for the creation of vulnerability indexes.

Remote sensing approaches for land use/land cover change in coastal areas and oceanic islands: an open science-based systematic review

In the current climate change context, detecting and monitoring relevant land use/land cover (LULC) changes in insular and coastal areas is critical as soon as they occur. This research consists of a systematic literature review of 167 open-access articles from January 2010 to June 2022, based on several parameters, namely year of publication, journals, geographic location of the study area, time range of the studies, data source, data type, sensors, remote sensing-based approach, data processing algorithms, accuracy assessment approach, and spatial resolution, using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) declaration as a guideline. The results revealed that the years 2020 and 2021 showed the highest number of studies published, namely 33 for each year (20%). The continent with the most case studies was Asia (48%), with China being the most productive country in this field (23%). The most analyzed time range was superior to 20 years (37% of the studies). Satellite imagery was the most applied data source (77%), followed by relevant historical data (e.g., land cover maps). The multispectral data was used in 77% of the studies, and the Landsat Mission represents three of five of the most used sensors. Normalized Difference Vegetation Index was the most applied remote sensing-based approach (10%), and the Maximum Likelihood Classifier Algorithm was the most widely used data processing algorithm (10%). The Overall Accuracy is the most applied accuracy assessment approach used in 85 papers (51%). Many articles used a 30-meter spatial resolution (69%), and higher resolutions completed the top 5 approaches. This study contributes to perceiving the main current approaches for monitoring LULC changes in insular and coastal environments to identify research gaps for future developments.

Eco-morphological evolution of the Bolivar Peninsula (Texas, U.S.A.) during the last 2,000 years: A multi-proxy record of coastal environmental changes

In the face of rapidly changing climate and increasing natural and anthropogenic disturbances, the long-term dynamics of coastal ecosystems in relation to hurricanes and human activities has become a focus of research for ecologists and geomorphologists across the Gulf of Mexico. This study integrates diatom, remote sensing, geochemical, and hydrodynamic analyses to document the ecological and morphological development of the barrier-island and estuary-wetland complex bordering Galveston Bay, Texas, from the late Holocene to the Anthropocene. The multi-proxy dataset revealed two major ecological shifts between 1320 and 840 cal yr BP and between 230 cal yr BP and 2008 AD in Galveston Bay. The first shift was driven by the landfall of a backdoor hurricane at ∼1000 cal yr BP in combination with the aperiodic and intense long-shore current that caused the barrier complex to retreat over fluvial deposits while the Bolivar Peninsula was growing toward the west. These morphological changes resulted in a narrower inlet, hence, restricting the marine influence from entering the bay and converting Galveston Bay to a wave-dominated estuary that was shallower and fresher. The second shift was caused by increasing modification to the waterway and infrastructures since 1800 AD. As a result, rapid sediment accretion was induced near the North Jetty, forming the current Bolivar Flats and setting the stage for mangrove colonization. The warming climate and hurricanes in recent decades acted as catalysts that accelerated mangrove expansion on the Bolivar Peninsula. Our results imply that the proposed coastal barrier system will likely increase the sediment deficit, alter the biogeochemical environment, and impact the primary productivity in the bay. However, on a regional scale, more and more mangrove stands are expected to appear around estuaries and lagoons, and along man-made jetties and barriers along the Gulf.

Vegetation History and Estuarine Ecology of the Texas Gulf Coastal Plain in Relation to Climate and Sea-Level Changes According to Three Pollen Cores

The vegetation history of the Texas Gulf Coastal Plain in the Holocene is considered according to pollen evidence from three coring sites where both terrestrial and marine ecology are reconstructed. These pollen sites record oscillations in the limit of the Southeastern US Forest zone in relation to climate changes, with a major, southward migration of the forest limit and expansion of the range limit of Betula nigra being recorded in the 6th millennium BP and a northward migration in the 4th millennium BP. The appearance of Rhizophora pollen also indicates increased tropical influence in the Middle Holocene. Moreover, changes in the salinity profiles of estuaries are reconstructed in relation to broader coastal environmental changes, such as sea-level oscillations and the formation of barrier islands, with a major sea-level transgression phase being recorded in the 4th millennium BP and still-stand conditions after the 3rd millennium BP. These vegetation changes are finally compared to occupational evidence of prehistoric humans in the Central Texas Gulf Coastal Plain region in relation to ecological factors. Here, human occupation of the coastal zone is correlated with afforestation, the proliferation of pecan and the emergence of low-salinity estuaries.

Impact of Waterfront City Development on Coastal Environmental Change and Local Wisdom in an Archipelago City

Impact of Waterfront City Development on Coastal Environmental Change and Local Wisdom in an Archipelago City

Fungal Diversity and Its Relationship with Environmental Factors in Coastal Sediments from Guangdong, China.

As one core of the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), Guangdong is facing some serious coastal environmental problems. Fungi are more vulnerable to changes in coastal environments than bacteria and archaea. This study investigated the fungal diversity and composition by high-throughput sequencing and detected basic parameters of seven environmental factors (temperature, dissolved oxygen, pH, salinity, total organic carbon, total nitrogen, and total phosphorus) at 11 sites. A total of 2056 fungal operational taxonomic units (OTUs) belonging to 147 genera in 6 phyla were recovered; Archaeorhizomyces (17.5%) and Aspergillus (14.19%) were the most dominant genera. Interestingly, a total of 14 genera represented the first reports of coastal fungi in this study. Furthermore, there were nine genera of fungi that were significantly correlated with environmental factors. FUNGuild analysis indicated that saprotrophs and pathogens were the two trophic types with the highest proportions. Saprotrophs were significantly correlated with total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP), while pathogens were significantly correlated with pH. This study provides new scientific data for the study of the diversity and composition of fungal communities in coastal ecosystems.

Coastal futures: New framings, many questions, some ways forward

Abstract Although coasts are frequently seen as at the frontline of near-future environmental risk, there is more to the understanding of the future of coastal environments than a simple interaction between increasing hazards (particularly related to global sea level rise) and increasing exposure and vulnerability of coastal populations. The environment is both multi-hazard and regionally differentiated, and coastal populations, in what should be seen as a coupled social–ecological–physical system, are both affected by, and themselves modify, the impact of coastal dynamics. As the coupled dance between human decisions and coastal environmental change unfolds over the coming decades, transdisciplinary approaches will be required to come to better decisions on identifying and following sustainable coastal management pathways, including the promotion of innovative restoration activities. Inputs from indigenous knowledge systems and local communities will be particularly important as these stakeholders are crucial actors in the implementation of ecosystem-based mitigation and adaptation strategies.

Historical changes in mollusc communities from a temperate chenier ridge system (Mont-Saint-Michel Bay, France)

Abstract Coarse-grained chenier ridges contain abundant mollusc shells that help to reconstruct the evolution of marine ecosystems throughout the Holocene, but few temperate environments have been studied. Historical surveys of the mollusc death assemblages sampled in a chenier ridge system from the southern English Channel were compared. Present-day active ridges provide a regional-scale, time-averaged signal of the subtidal mollusc diversity. Back-barrier fossil ridges dated to the Early Medieval Period document pre-industrial baseline conditions. Shellfish farming and invasive species had little impact on mollusc death assemblages recovered from active ridges so far. However, detection of these recent changes is delayed due to taphonomic inertia as shell ages can span more than 1000 years, even in active ridges. Differences in taxonomic and functional composition between fossil and present-day ridges show a decline in grazing and carnivorous species related to macrophytobenthic habitats (seagrass beds and macroalgal belts) and a shift towards a suspensivore-dominated community. The study confirms water temperature as a major driver of ecological change in the English Channel, as warm-water species are more common in present-day ridges. Shelly chenier ridges are useful records of ecological changes in coastal environments that offer a temporal coverage far exceeding that of long-term ecosystem monitoring studies.

Holocene coastal evolution and environmental changes in the lower Río Guadiaro valley, with particular focus on the Bronze to Iron Age harbour ‘Montilla’ of Los Castillejos de Alcorrín (Málaga, Andalusia, Spain)

AbstractPhoenicians were the first to systematically develop the area surrounding the Strait of Gibraltar at the end of the 9th century B.C. Following pioneering studies in the Río Guadiaro estuary (Málaga/Cádiz) in the 1980s, a German‐Spanish cooperation project focussed on the role of indigenous people in the Phoenician colonisation trading networks at Los Castillejos de Alcorrín (Manilva, Málaga), one of the most important Early Iron Age settlements in southwestern Iberia. In the recent past, combined with systematic archaeological surveys, geoarchaeological research embedded in the interdisciplinary project ‘Archeostraits’ aimed at (i) deciphering palaeoenvironmental and coastal changes in the surroundings of Los Castillejos de Alcorrín throughout the mid‐ to late Holocene; (ii) constraining palaeoenvironmental conditions during early Phoenician colonisation; and (iii) better understanding human–environment interactions during the Final Bronze and Early Iron Age (i.e., end of 9th and 8th centuries B.C.). Coring transects along the Río Guadiaro allowed for differentiating successive palaeoenvironments and for establishing a chrono‐stratigraphy for the Holocene sedimentary infill of the valley. Based on these results, the deposition of shallow marine sands, overlying deltaic deposits of alternating sand and mud, and the subsequent development of lagoonal conditions in the lower Guadiaro valley took place before the Phoenicians established the first settlements along the coast.

Coastal erosion narratives in the Gulf of Mexico: implications for climate change governance

This article presents a study of coastal erosion narratives by the Mexican government, scientists, and local fishers in coastal communities in the Gulf of Mexico. It shows how plans to enroll fishing communities into programs to adapt to or to slow coastal erosion are based on simplified environmental narratives that rely on global climate change as the main cause of coastal erosion. They discount local processes and local explanations, as well as scientific studies that outline complex multi-scalar explanations for coastal erosion. Government narratives frame global climate change, as manifested in increased frequency and intensity of hurricanes and other hydrometereological extreme events and sea level rise, as the main causes of changes in coastal environments, including coastal erosion They fail to acknowledge other causes including the environmental degradation caused by the influential oil industry. In contrast, fishers' more complex and locally-embedded narratives are shaped by their long-term struggles against the state-owned oil company, whom they hold primarily responsible for coastal erosion in their communities. Scientists similarly emphasize the importance of local and regional processes, with climate change understood primarily as having significant impacts in the future, but less so in the recent past. Differences in temporal and geographical scaling among these narratives highlight the importance of considering how the translation of climate change adaptation programming from the global to diverse local situations would ideally consider site-specific power relations as well as community-based perspectives.

Climate Change Impacts to Coastal Communities in Kudat, Sabah, Malaysia

Climate change is the among major threats to marine ecosystems, representing both a challenge and an opportunity for researchers and the government. Impacts are not experienced uniformly, and the existing unbalanced ecosystems will be further exacerbated without urgent action to mitigate climate change and enhance community resilience. The objective of this study is to draw insights on the impact of climate change based on the coastal community input and environment change at Kimihang, Kelambu Beach and Bavang Jamal, Kudat, Sabah. Interviews and fieldwork were carried out in March and August 2020. The unstructured questionnaire was applied to 15 respondents to know in-depth experiences on the impacts of climate change. The data were presented as timeline narration before and after the year 2000. Results show that the respondents addressed climate change through the reduction of natural resources yields, and change of surrounding environment, career paths of the young generation, and the existence of structural management. The coastal communities were found to have lacked the know-how and awareness to manage and maximized the use of their coastal resources sustainably. This is to suggest that constructing the best adaptation strategies requires attention in this region.

Anthropogenic influences on coastal environmental changes in the Mekong Delta: a study from Ben Tre Province, Southern Vietnam.

Low-lying coastal environments are highly dynamic and sensitive to natural as well as anthropogenic perturbations. Climate change, sea level rise, storms and tsunamis are the natural phenomena that affect the deltaic coasts in Southeast Asia in general and Vietnam in particular. The effects of these phenomena can be exacerbated by human activities such as mangrove deforestation, aquaculture and infrastructure development. Conversely, the low-lying coastal areas are important in the economic development of Southeast Asian countries. In the Vietnamese Mekong Delta, coastal areas have been affected by a number of factors, such as climate change, sea level rise, aquaculture, pollution and tourism-related activities in recent decades. The present study investigated shoreline changes, expansion of aquaculture ponds, soil salinity changes and salinity intrusion in the river systems along the coastal areas of Ben Tre Province in the Vietnamese Mekong Delta between 1998 and 2020 using satellite imagery and field data. Variations in erosion and accretion were found to be not unique along the coast of Ben Tre. There was a rapid expansion of aquaculture ponds between 1998 and 2015 and a slight decline since then. Soil salinity has been increased between 1998 and 2020; it is seen from recent satellite data that soil is becoming more saline in the inland areas of Ben Tre. Saltwater intrusion into the rivers of Ben Tre is considered associated with El Niño-La Niña conditions. It is suggested that reforestation of abandoned shrimp ponds in Ben Tre by mangrove vegetation can be effective as a bioshield against coastal hazards, such as sea level rise and shoreline erosion.

Coastal Landscapes, Environmental Change, and Maritime Cultural Heritage Resources in Morocco: The Case Study of Essaouira

Coastal Landscapes, Environmental Change, and Maritime Cultural Heritage Resources in Morocco: The Case Study of Essaouira

Investigation of coastal environmental change at Ruddons Point, Fife, SE Scotland

Ruddons Point, on the Firth of Forth coastline, Scotland, is a laterally extensive terrace of glacial and marine sediment deposits raised above current sea-level, situated near to Kincraig Point, a key site that records a series of stepped erosional platforms carved into the local bedrock, interpreted as post Last Glacial Maximum palaeoshorelines. The deposits at Ruddons Point continue inland, with exposures of the raised sands and gravels cut by the local river, the Cocklemill Burn. The site provides an opportunity to examine the depositional history through the Late Devensian and Holocene. Geophysical survey aided in interpreting characteristics of subsurface sediments such as the transition between the younger saltmarsh sediments and older underlying sands and clays below, which slope in a northerly direction. A chronology obtained through optically stimulated luminescence (OSL) dating spans from c. 29 ka for sands and clays at an elevation of −0.66 mOD to surface windblown sands at <300 years, at an elevation of 8.45 mOD. A basal peat, dated by radiocarbon dating to the early Holocene at c. 9.2 ka, formed prior to the Main Postglacial Transgression. Dating of inland raised marine deposits along the Cocklemill Burn records dates ranging from c. 8.9 to c. 4.3 ka. The raised marine deposits of Ruddons Point range from c. 8.1 to c. 2.9 ka, deposited unconformably on glacial tills and clays. This multidisciplinary field study builds depositional scenarios utilizing two dating methods, spanning the last c. 29 ka, to better understand coastal evolution for a region which has experienced complex relative sea-level variations. Supplementary material : Supplementary data related to this research article is available at https://doi.org/10.6084/m9.figshare.c.6080999 Thematic collection: This article is part of the Early Career Research collection available at: https://www.lyellcollection.org/topic/collections/early-career-research