Coastal Environmental Changes Research Articles

Methodological limitations of CLC to assess land cover changes in coastal environments

CORINE land cover (CLC) is used to analyze the state and evolution of land covers in the coastal zone, which is recognized as one of the most important ecosystems providing a wide range of services to human societies. CLC data were processed and spatially analyzed using GIS to study land cover changes in an area of 10 km landwards from the coastline along the Iberian Peninsula, including contrasted coastal zones in Portugal and Spain. A series of methodological limitations arising from the results of this study were investigated. In particular, we concentrated on the effect that spatial definition, delimitation of the coastline, characterization and delimitation of wetlands and water bodies, and the coherence in land cover changes exerted on the pattern and magnitude of land cover temporal changes. For example, in Galicia, “water courses” apparently increased by 520% whereas “intertidal flats” were reduced by 77% between 2000 and 2006. In Northern Portugal, “salt marshes” increased by 40% and “coastal lagoons” decreased by 90% over the same period. The effect of these different delimitations would represent a 30% increase in the Galician coastline length. Some ancillary data such as topographic maps, orthophotographs or satellite imagery are presented as a necessary complement to accurately estimate land cover changes and some methodological cautions are discussed.

Hypothetical Influence of Bacterial Communities on the Transfer of 14C-Depleted Carbon to Infaunal Foraminifera: Implications for Radiocarbon Dating in Coastal Environments

ABSTRACTLittle is known about the potential complications that may arise from the use of coastal foraminifera for radiocarbon (14C) dating. The aim of this study is to report the fortuitous finding of 14C-dated Haynesina germanica individuals picked from two sediment cores (Pertuis Charentais, France), which appeared 2500–2000 years older than their expected age of deposition. Stratigraphical and micropaleontogical evidence have ruled out the possible effect of reworking of calcareous tests from previous strata. Similar anomalous 14C ages were obtained on abundant lignocellulose debris recovered from the cores, which are supplied by rivers flowing into the study area. Given that H. germanica is an infaunal species, we hypothesize that in-situ living individuals acquired the 14C-depleted isotopic signature of lignocellulose debris within the sediment prior to definitive burial, following an unexplored pathway of carbon transfer between the two compartments. Based on the literature, we propose a plausible explanation, which involves bacterial communities living in the study area. This putative role of bacteria may have considerable importance for past and future studies of Holocene environmental changes in coastal environments. Further work is now needed to explore this hypothesis with more robust, direct evidence based on comprehensive geochemical, geochronological and microbiological studies.

The submarine landscape of the ‘Jurassic Coast’ World Heritage Site, Dorset, UK and its Setting

This paper reviews recent studies of the seabed offshore from the Jurassic Coast and discusses their significance for understanding landforms of the World Heritage Site’s Setting as well as adding to understanding of the structures exposed in the cliffs. The processes of coastal formation as sea-levels rose and fell during the Pleistocene and in the recent post-glacial period are critical for this as they reveal the landforms which preserve former shorelines. Detailed surveys of the seabed provide evidence of the low slope of much of this seabed and so enhance the potential to interpret older terrestrial landforms which have been attributed to uplift of former sea beds. Considering both the seabed and the coast from the Pleistocene to the Anthropocene means that it is possible to assess the human impact on these landforms and processes, as well as the natural timescale within which changes occur. The paper describes the seabed geomorphology, relating this, where appropriate, to both the coastal landforms and the exposed structures. Current interpretations of the seabed features and their implications for our understanding of the recent evolution of the Site and Setting are explored. The features of the coast and adjacent sea bed at different phases of the changing coastal environment are discussed to the extent that the available evidence makes this possible, but for much of the area this remains speculative.

Investigation of Coastal Environment Change Using Wave Measurement Sensors and Geographical Laser Scanner

The construction of large-scale coastal structures in any coastal area may not only have direct effects on the coastal environment in that vicinity but also cause severe property damage. In order to prevent this problem, probable effects should be appreciated before any construction and the mechanism that may cause any probable damage must be accurately analyzed along with the plans to minimize damage. This study sought to analyze the cause and mechanism of damage inflicted on coasts by artificial structures through reviewing beach erosions that have occurred on beaches on the east coast of Korea after the large-scale construction of artificial structures, for which wave heights were measured in the vicinity of those structures, and the correlation between the measurements and the analysis data of waves and coastal erosion on the surrounding beach was analyzed. In addition, the correlation between coastal erosion and wave data was applied in order to understand what impact large waves have in relation to sand loss. Accordingly, a movable-bed physical model test was employed to appraise the factors that cause coastal erosion to take place.

Spatial and temporal trends of melamine and its derivatives in sediment from Lake Shihwa, South Korea.

Occurrence, spatial distribution, and temporal trends of melamine and its derivatives (ammeline, ammelide, and cyanuric acid) were investigated in surface sediment and two sediment cores collected from Lake Shihwa, South Korea. ∑Melamine (sum of melamine and its three derivatives) was found in all surface sediment samples at concentrations that ranged from 16.6 to 4390 ng/g dry weight (dw), with an average value of 202 ng/g dw. ∑Melamine concentrations exhibited a clear spatial gradient, in decreasing order, as: creeks (mean: 577 ng/g dw) > inshore locations (41.9 ng/g dw) > offshore locations (24.3 ng/g dw). ∑Melamine concentrations were notably high in sediment collected near wastewater treatment plant (WWTP) outfalls. Melamine was the most prevalent compound in sediment collected from creeks (87%) and WWTP outfall locations (48%), whereas cyanuric acid was the dominant compound in sediment from inshore (51%) and offshore (63%) locations. The historical profiles of ∑Melamine in sediment cores corresponded with coastal development and environmental changes in this region. This is the first study to document the occurrence and temporal distribution of melamine in sediment cores, and this information is useful in understanding the fate of these relatively less-studied chemicals in the environment.

The perception of climate-related coastal risks and environmental changes on the Rangiroa and Tikehau atolls, French Polynesia: The role of sensitive and intellectual drivers

French coastal policies have recently put greater emphasis on the need to better inform coastal populations about coastal risks in the context of climate change, in particular in French overseas territories that are nationally recognized as hotspots. It is therefore critical to further assess local populations' knowledge and perceptions of climate-related coastal risks. In this respect, we ran a social survey among inhabitants of two atolls of French Polynesia in the Pacific Ocean, using a questionnaire and semi-structured interviews largely based on images of landscapes. The results show that (1) coastal risks are not considered as a danger but only as a problem, and that (2) inhabitants have a very clear perception of the changes that have occurred locally over the last 70 years with respect to weather, climate, corals and beaches. (3) Interviewees generally show some knowledge about the notion of global climate change and its potential local impacts. (4) However, a multiple correspondence analysis distinguishes four groups (the ‘informed’, ’poorly informed, ‘uninformed’ and ‘distant’ groups) separated by age and gender, but also by levels of education and urbanization. The discussion therefore focuses on the most important drivers of climate change perception, showing a disconnection between atolls and generations: rural and older inhabitants present more sensitive mechanisms of risk perception and urban and younger interviewees more intellectual ones. A major challenge consists in bringing these dimensions closer by better integrating, on an intellectual level, local climate-related coastal risks into school programs, and by defining, on a more sensitive level, an ambitious cultural and environmental policy to allow young generations to keep contact with their original living environment. Highlighting the interest of this survey, risk management and adaptation policies now support the reactivation of local knowledge and practices.

Special collection: Coastal Environmental Changes under Increasing Anthropogenic Impacts

Special collection: Coastal Environmental Changes under Increasing Anthropogenic Impacts

Coastal environmental changes under increasing anthropogenic impacts: an introduction

Coastal environmental changes under increasing anthropogenic impacts: an introduction

Special collection: Coastal Environmental Changes under Increasing Anthropogenic Impacts

Special collection: Coastal Environmental Changes under Increasing Anthropogenic Impacts

Dynamic land use and its policy in response to environmental and social-economic changes in China: A case study of the Jiangsu coast (1750–2015)

With the rapid industrialization and urbanization, China’s mainland coasts have witnessed an increasing challenge of sustainable development. Policy-making and management in coastal development also need an in-depth understanding of long term land use changes. Historically, coastal land use and its policy in China experienced a complex and tortuous evolution from the preindustrial era to modern times. However, there is a lack of detailed treatment in previous studies, about the issues of the policy response to environmental and social-economic conditions. Using an approach of historical document analysis and multidisciplinary synthesis, based on the case from the Jiangsu coast, we explore the land use changes and its policy response for China’s mainland coasts on a centennial time scale. The results show that the land use policy had different performances in response to the changes of environment and social-economy at different stages, with a dynamic shift from passive to active response. During the 18–19th centuries, the management framework was associated with the monopolized land use policy that was dominated by the government's interests of salt industry; there were few initiatives to take into account the environment changes and stakeholder conflicts. Yet, during the 20th century, the emphasis of the policy was placed on reclamation and diversified industry, reflecting the pressure from the coastal environment change and social-economic situation. At the same time, the adjustment of land use policy became more frequent. Population growth and physical environment change are the two major driving forces for the observed shifts. The study on the long term change of land use and policy response for China’s mainland coasts may provide a reference frame to be considered for future sustainable development and adaptation.

Palaeoenvironmental reconstructions during the Meso- to Neolithic transition (9.2–5.3 cal. ka BP) in Northwestern France: Palynological evidences

Sedimentological, palynological, and micropalaeontological studies carried out throughout the first half of the Holocene, during the Mesolithic/Neolithic transition in the Bay of Brest (i.e. 9200–9000 and 6600–5300 cal. BP) and in the Bay of Douarnenez (i.e. 9200–8400 cal. BP), allowed characterizing coastal environmental changes under the increasing influence of the relative sea-level rise. The gradual flooding of the two studied sites implied a transition from river valleys to oceanic bays as revealed by the gradual retreat of salt marsh environments, as detected through palynological analysis. In addition, these high-resolution studies highlight the regional imprint of the North Atlantic millennial climate variability in north-western coastal environments. Two cold climate events are indeed suggested to have been locally marked by a moisture increase, mainly detected by increases in Lingulodinium machaerophorum, Corylus, and Alnus percentages at 8550 cal. BP in the Bay of Douarnenez and at 6250 cal. BP in the Bay of Brest. Moreover, regarding the Neolithic transition timing in the Bay of Douarnenez, large pollen grains of Poaceae (i.e. Cerealia-type pollen grains) have been detected at around 8600 cal. BP, that is, 1500 years before the general accepted cereal cropping appearance in Western France. These results, consistent with other palynological studies conducted in the French Atlantic coast, could underline a Mesolithic ‘proto-agriculture’ in Brittany.

Human settlement and Mid-Late Holocene coastal environmental change at Cape Krusenstern, Northwest Alaska

Archaeologists hypothesize that mid-late Holocene environmental variability played a role in several significant western Arctic cultural developments including population fluctuations, the evolution of Arctic maritime adaptations, and Arctic-wide migrations. Further evaluation of these hypotheses requires higher resolution archaeological and paleoecological datasets than are currently available. In response, we undertook an interdisciplinary study at Cape Krusenstern, a large coastal site complex in northwest Alaska, which was occupied over the last ca. 5000–6000 years. Our goals were to refine local cultural and paleoenvironmental chronologies and to explore the question of how local environmental change may have influenced local settlement history. The resulting revised chronology and depositional units confirm and refine prior interpretation of the local archaeological settlement history. New geomorphological data on coastal environmental change and post-depositional modification of the Cape Krusenstern beach ridge system also provide information about patterns of archaeological site preservation, indicating periods of potentially poorer site preservation around 3990 cal BP; this informs interpretation of forager settlement data. Furthermore, our findings suggest that climate-driven changes in the coastal environment at Cape Krusenstern may not be as determinative in terms of landscape evolution as previously thought. Future work should focus on further investigating the relationship between beach ridge development and regional climatic patterns on a regional scale, as this has implications for use of beach ridges as a mid-late Holocene climate proxy. Continued efforts to build paleoenvironmental reconstructions of higher temporal and spatial resolution for the region will help address remaining questions about the relationship between local coastal environmental changes and regional patterns, and the impacts of these environmental shifts on local residents.

Sedimentary Environment Evolution in East China's Coastal Tidal Flats: The North Jiangsu Radial Sand Ridges

Xu, M.; Meng, K.; Zhao, Y., and Zhao, L., 2019. Sedimentary environment evolution in East China's coastal tidal flats: The North Jiangsu radial sand ridges. Journal of Coastal Research, 35(3), 524–533. Coconut Creek (Florida), ISSN 0749-0208.The North Jiangsu radial sand ridges (NJRSR) are a unique sedimentary system comprising the largest silt and mud coastal tidal flat in China. Many factors influence its tidal geomorphology sensitivity when responding to the marine environment and human activities. In this study, three typical core samples were collected from sampling points near Xinyang Gang (XYG), Chuandong Gang (CDG), and Xiaoyangkou Gang (XYK). 210Pb and 137Cs radionuclide dating was used to estimate the sedimentation rate of the tidal flat. On the basis of combined sediment grain size and reclamation history over the last 50 years, the evolution of the NJRSR coastal tidal flat sedimentary environment under the impact of human activities and the changing coastal environment was examine. The result indicated that the predominant type of sedimentary deposition is sandy silt; however, sediment composition varies because of coastal reclamation activities extending into the sea and with changes in sediment source and depositional forces. Average sedimentation rates of the three core samples were 1.27, 1.85, and 2.43–3.3 cm/y, respectively, reflecting increasing sedimentation rates from north to south. However, sedimentation rates over the past century have gradually declined in core XYG because of a reduced supply of materials from northern sources. Moreover, sand content has increased in the north since the 1980s, and grain size has become coarser. In the middle sample, a sudden change in sediment composition occurred in the 1950s–60s, exhibited by a significant reduction in sand content but an increase in silt content and finer grain sizes. In the south, grain size coarsened initially before becoming finer, likely because of a reduction of eroded material from the Yellow River in the north, increased coastal reclamation activities, and changes in sedimentary dynamics.

Quantification of cliff retreat in coastal Quaternary sediments using anatomical changes in exposed tree roots

AbstractSea cliffs represent 80% of the world's coasts and can be found virtually in all types of morphogenetic environments. Most studies on rocky environments focused on the impacts of modern sea level rise on cliff stability derived from sequential surveys, direct measurements or erosional features in anthropogenic structures. In this study, we explore the potential of dendrogeomorphic techniques to quantify multidecadal changes in coastal environments on Porquerolles Island (France). We sampled a total of 56 cross‐sections from 16 Pinus halepensis Mill. roots growing on former alluvial deposits and on sandy‐gravelly cliffs to quantify mean annual cliff retreat rates as well as changes in cliff geometry. Anatomical changes in roots have been used successfully in the past to quantify continuous denudation rates on slopes, channel incision and gullying processes but the approach has not been used so far in a coastal cliff context. At Porquerolles Island, reconstructed rates of cliff retreat cover 30–40 years and show average erosion rates between 0.6 and 3.9 cm yr−1 (average: 2.1 cm yr−1). Highest rates are observed at Pointe de la Tufière (2.6–3.9 cm yr−1), a small rock promontory that is more exposed to wave and storm surges than the remainder of the study area. By contrast, lower erosion rates are recorded at cliffs protected by the La Courtade pocket beach (0.6–1.9 cm yr−1). This contribution demonstrates that dendrogeomorphic analyses of roots clearly have a significant potential and that they are a powerful tool for the quantification of multidecadal rates of cliff retreat in areas where measurements of past erosion are lacking. More specifically, the approach also has clear advantages over the shorter time series obtained with repeat monitoring (e.g. terrestrial laser scanning, sensors, erosion pins) or over longer, but more coarsely resolved records obtained from aerial photographs or radio‐nuclides. © 2018 John Wiley & Sons, Ltd.

Fostering coastal community resilience: Mobilising people‐place relationships

There are new, and increasing, pressures facing coastal communities, including socio‐economic and environmental change, exploitation of resources, urban development and the predicted impacts of climate change. The cumulative and interacting effect of these challenges may result in socio‐economic and physical decline. This paper responds to calls for more detailed investigation into coastal regeneration by providing empirical evidence (interviews, observations, policy analysis) on specific coastal resorts on the island of Ireland. In doing so it builds on an emerging area of research that suggests coastal regeneration may be theoretically and practically informed by “resilience thinking”. The case study findings highlight differing, and sometimes competing values, perceptions and priorities at the local level and highlight the challenges facing striving resorts seeking to find their contemporary identity and enhance their resilience to future change.

Stable isotope analyses of manatee bones measure historical nitrogen pollution in Florida waters, 1975–2010

Nutrient pollution is a key driver of ecological change in coastal marine environments. Over the last 150 years, the dominant source of nitrogen in coastal waters has shifted from sewage to synthetic fertilizer in many regions including the Caribbean. Here, we use stable nitrogen isotope analyses of bones from manatees (Trichechus manatus latirostris) from along the coast of Florida, USA, to determine whether they record changes in coastal nitrogen pools over a 35-year period. Nitrogen isotopic composition (δ15N) of 172 manatee bones declined statewide at a rate of 0.07‰ year−1, from 9.8‰ in 1975 to 7.3‰ in 2010, suggesting a greater relative abundance of fertilizer, which has a lower δ15N value than that of sewage. Of the four coastal regions of Florida we examined, δ15N values declined significantly in two: the northeast and northwest coasts. The southeast coast, which includes some of the most densely populated counties and cities, had the highest mean δ15N values. In contrast, δ13C values did not vary over time or among coastal regions within the state, indicating that the source of the plant material in the manatee diets did not change substantively over the course of the study period. The general decline in δ15N values may be due to an increase in synthetic fertilizer nitrogen use by the agriculture industry in Florida, but that trend has now abated as overall fertilizer use has stabilized. It is also likely that the increased use of deep injection wells for treated wastewater disposal, which diverts sewage-derived nitrogen away from coastal waters, contributed to the long-term decline in δ15N values in spite of the state’s rising human population.

Geoinformatic analysis of vegetation and climate change on intertidal sedimentary landforms in southeastern Australian estuaries from 1975–2015

Vegetation canopies represent the main ecosystems on intertidal landforms and they clearly respond to changes in coastal environments. Climate change, including temperature, precipitation and sea level rise, are affecting the health and distribution of coastal vegetation, as well as the runoff and sedimentation rates that can impact coastal areas. This study has used the normalized difference vegetation index (NDVI) to investigate vegetation canopy dynamics on three different coastal sites in southeastern Australia over the past 47 years (1975–2015). NDVIs temporal-datasets have been built from satellite images derived from Landsat 1–8. These were then regressed to the climatic and geomorphic variables. Results show clear increases in NDVI at Towamba and Wandandian Estuaries, but a decline at Comerong Island (southeastern Australia). The sedimentation rate has the most significant positive impact on NDVI since it has the potential to provide additional space for vegetation. Temperature and sea level rise have positive effects, except on Comerong Island, but rainfall has no significant effect on the NDVI at any site. Different NDVI trends have been recorded at these three coastal sites reflecting different correlations between the vegetation, climatic and geomorphic (as independent) variables. The geomorphological characteristics of the highly-dynamic intertidal estuarine landforms, which are subject to active erosion and deposition processes, have the largest impact on vegetation cover and, hence, on NDVI. Assessing the vegetation canopy using NDVI as an evaluation tool has provided temporal-dynamic datasets that can be correlated to the main individual environmental controls. Such knowledge will allow resource managers to make more informed decisions for sustainable conservation plans following the evaluation the potential consequences of any environmental changes.

Adaptation Decision Support: An Application of System Dynamics Modeling in Coastal Communities

This research develops and applies a system dynamics (SD) model for the strategic evaluation of environmental adaptation options for coastal communities. The article defines and estimates asset-based measures for community vulnerability, resilience, and adaptive capacity with respect to the environmental, economic, social, and cultural pillars of the coastal community under threat. The SD model simulates the annual multidimensional dynamic impacts of severe coastal storms and storm surges on the community pillars under alternative adaptation strategies. The calculation of the quantitative measures provides valuable information for decision makers for evaluating the alternative strategies. The adaptation strategies are designed model results illustrated for the specific context of the coastal community of Charlottetown, Prince Edward Island, Canada. The dynamic trend of the measures and model sensitivity analyses for Charlottetown—facing increased frequency of severe storms, storm surges, and sea-level rise—provide impetus for enhanced community strategic planning for the changing coastal environment. This research is presented as part of the International Community-University Research Alliance C-Change project “Managing Adaptation to Environmental Change in Coastal Communities: Canada and the Caribbean” sponsored by the Social Science and Humanities Research Council of Canada and the International Development Resource Centre.

A spatial dynamic model of population changes in a vulnerable coastal environment

ABSTRACTThis study developed a spatial dynamic model to examine the coupled natural–human responses in the form of changes in population and associated developed land area in the Lower Mississippi River Basin region. The goal was to identify key socioeconomic factors (utility) and environmental factors (hazard damages, elevation, and subsidence rate) that affected population changes, as well as to examine how population changes affected the local utility and the local environment reciprocally. We first applied areal interpolation techniques with the volume-preserving property to transform all the data at Year 2000 into a unified 3 km by 3 km cellular space. We then built an Elastic Net model to extract 12 variables from a set of 33 for the spatial dynamic model. Afterward, we calibrated the neighborhood effects with a genetic algorithm and use the spatial dynamic model to simulate population and developed land area in 2010. Furthermore, we took a Monte Carlo approach for analyzing the uncertainty of the model outcome. Our accuracy assessment shows that the model on average slightly overpredicts the number of population and the developed land percentage at 2010, as indicated by the low values of mean absolute deviation (MAD) due to quantity. On the other hand, the MADs due to allocation are larger than the MADs due to quantity, with most outliers found in the New Orleans region where population and urban development declined significantly during 2000–2010 after Hurricane Katrina. The proposed model sheds light on the complex relationships between coastal hazards and human responses and provides useful insights to strategic development for coastal sustainability.

Large-scale climatic effects on traditional Hawaiian fishpond aquaculture.

Aquaculture accounts for almost one-half of global fish consumption. Understanding the regional impact of climate fluctuations on aquaculture production thus is critical for the sustainability of this crucial food resource. The objective of this work was to understand the role of climate fluctuations and climate change in subtropical coastal estuarine environments within the context of aquaculture practices in Heʻeia Fishpond, Oʻahu Island, Hawaiʻi. To the best of our knowledge, this was the first study of climate effects on traditional aquaculture systems in the Hawaiian Islands. Data from adjacent weather stations were analyzed together with in situ water quality instrument deployments spanning a 12-year period (November 2004 –November 2016). We found correlations between two periods with extremely high fish mortality at Heʻeia Fishpond (May and October 2009) and slackening trade winds in the week preceding each mortality event, as well as surface water temperatures elevated 2–3°C higher than the background periods (March-December 2009). We posit that the lack of trade wind-driven surface water mixing enhanced surface heating and stratification of the water column, leading to hypoxic conditions and stress on fish populations, which had limited ability to move within net pen enclosures. Elevated water temperature and interruption of trade winds previously have been linked to the onset of El Niño in Hawaiʻi. Our results provide empirical evidence regarding El Niño effects on the coastal ocean, which can inform resource management efforts about potential impact of climate variation on aquaculture production. Finally, we provide recommendations for reducing the impact of warming events on fishponds, as these events are predicted to increase in magnitude and frequency as a consequence of global warming.