Coastal Environmental Changes Research Articles

Low-molecular-weight organic acids as important factors impacting seawater acidification: A case study in the Jiaozhou Bay, China

Low-molecular-weight organic acids (LMWOAs) are ubiquitous water-soluble organic compounds with mass production worldwide, but their influence on coastal marine environments is still lack of consideration. In this study, we select a typical nearshore bay - the Jiaozhou Bay, which is surrounded by Qingdao — a city with modern manufacture, agriculture, aquaculture and service industry, as study area, to investigate the effect of LMWOAs on the nearshore marine environment, and their impact on seawater acidification in coastal areas. During Sep. 2016 to Aug. 2017, we identified three different LMWOAs – acetic acid (AA), formic acid (FA) and lactic acid (LA), with average concentrations of 46.7, 13.9 and 1.4 μmol·L−1 in the seawater of the bay, respectively. Due to the establishment of the Jiaozhou Bay Bridge, the seawater exchange capacity was weakened and thereby the concentration and stocks of AA and FA increased. As weak acids in seawater, the influence of LMWOAs on the seawater acidification of the Jiaozhou Bay was investigated. LMWOAs had significant impact on seawater pH and every 10 μmol·L−1 LMWOA caused an average of 0.02 pH unit decrease. From 2010 to 2017, pH value in the seawater of the bay decreased by about 0.103 and LMWOAs contributed about 83% of its decrease. Besides, two models were established to estimate the influence of LMWOAs on the seawater pH by applying the data set of dissolved inorganic carbon (DIC), total alkalinity (TA) and LMWOAs. The results showed that LMWOAs could enhance acidification of coastal seawater. Considering the importance of LMWOAs in seawater, it is necessary to evaluate their future changes in coastal marine environments. This study initiated a way to identify the source of LMWOAs in seawater and to evaluate their contribution to seawater acidification, and also provided a series of dataset for future study on LMWOAs in coastal environment.

Assessing and managing design storm variability and projection uncertainty in a changing coastal environment

Coastal urban infrastructure and water management programs are vulnerable to the impacts of long-term hydroclimatic changes and to the flooding and physical destruction of disruptive hurricanes and storm surge. Water resilience or, inversely, vulnerability depends on design specifications of the storm and inundation, against which water infrastructure and environmental assets are planned and operated. These design attributes are commonly derived from statistical modeling of historical measurements. Here we argue for the need to carefully examine the approach and associated design vulnerability in coastal areas because of the future hydroclimatic changes and large variability at local coastal watersheds. This study first shows significant spatiotemporal variations of design storm in the Chesapeake Bay of the eastern U.S. Atlantic coast, where the low-frequency high-intensity precipitations vary differently to the tropical cyclones and local orographic effects. Average and gust wind speed exhibited much greater spatial but far less temporal variability than the precipitation. It is noteworthy that these local variabilities are not fully described by the regional gridded precipitation used in CMIP5 climate downscaling and by NOAA's regional design guide Atlas-14. Up to 46.4% error in the gridded precipitation for the calibration period 1950–1999 is further exacerbated in the future design values by the ensemble of 132 CMIP5 projections. The total model projection error (δM) up to −61.8% primarily comes from the precipitation regionalization (δ1), climate downscaling (δ2), and a fraction from empirical data modeling (δE). Thus, a post-bias correction technique is necessary. The bias-corrected design wind speed for 10-yr to 30-yr storms has small changes <20% by the year 2100, but contains large spatial variations even for stations of close proximity. Bias-corrected design precipitations are characteristic of large spatial variability and a notable increase of 2–5 year precipitation in the future along western shores of the Lower and Middle Chesapeake Bay. All these accounts point to the potential vulnerability of water infrastructure and water program in coastal areas, when the hydrological design basis using regional values fails to account for significant spatiotemporal precipitation variations in local coastal watersheds.

Alnus glutinosa L. Gaertn. as potential tree for brackish and saline habitats

Over 800 million hectares of land worldwide are affected by salinity. Predicted scenarios of global climate change include a rise in sea level, which may severely affect coastal forest areas. Black alder (Alnus glutinosa) is a tree species known to tolerate heavily waterlogged soils, but its salt resistance is still unclear. The aim of our study was to assess A. glutinosa growth under soil salinity as a possible tree for wet, salt-affected sites in a changing coastal environment due to climate change. We hypothesised that: a) growth parameters are directly related to soil conditions; and b) salinity and waterlogging can limit black alder growth. For our research, we evaluated 9-11-year-old black alder plantations in Poland, one in a saline area and two reference sites on non-saline soils (one with higher moisture content). The growth of trees at each site was characterised by calculating the growth success, mean diameter at breast height, the mean height and the standard deviations from the means. We also calculated the distribution of diameters in each population, regression models for growth as the relationship between diameter and height, and coefficients of variance. The means between sites were compared by one-way ANOVA with Scheffe’s post-hoc comparisons. To characterise soil conditions we took soil samples for each site and compared their properties by the same statistical tests.Under saline conditions, black alder growth was limited in terms of height, diameter at breast height and growth success. Salinity also affected the trees’ variability, growth form and growth pattern. However, these effects were comparable to those observed in the non-saline waterlogged site. The models of growth described by regression demonstrated similar reduction of growth dynamics in these two sites. Moreover, the coefficients of variation in diameter and height of trees in these sites were similar and higher than in non-stressed site. In addition, at the saline and waterlogged sites black alder trees had relatively large number of root suckers, whereas in non-stressed site this was not the case. On the plantations in stressed environments there had been losses in the A. glutinosa stand, which had been spontaneously settled by other species of trees and shrubs, which increased species richness. Therefore, regarding climate change, in our opinion black alder can be considered as an option for planting in brackish coastal areas, where nature conservation and watershed management are at least as important as wood production.

Don't get too attached: Property–place relations on contested coastlines

Societies are now squarely facing the risks of environmental and climatic change, and developed coastlines are ground zero. Climate change will cause damage to, or loss of, coastal property – property that, in most Western societies, is considered a high net value asset. This paper examines cultural ideas about private property and the complexities of using land use planning law as an enabler of climate change adaptation. It reports the findings of qualitative research that explores how residents living in coastal Australia respond to the risks to their property and to the places they live that are posed by sea level rise and other coastal climate change‐related risks. By reporting how residents experience their material coastal environment, and how they relate with and to ideas of “property” in a coastal environmental change context, this paper contributes to both coastal policy and to legal geography scholarship.

Wetland expansion on the continental shelf of the northern South China Sea during deglacial sea level rise

To identify environmental causes for past changes in vegetation in subtropical East Asia, we present carbon isotope compositions of plant-wax n-alkanes and provide estimates of the C4-plant contribution across the past four glacial terminations and interglacials, based on cores recovered from the northern South China Sea. Our results show a comparable C4-plant contribution between the Last Glacial Maximum (LGM) and the Holocene. An increase of the C4-plant contribution by 15–20% is found for Terminations IV, II and I relative to subsequent interglacial peaks, coeval with an expansion of Cyperaceae and Poaceae. In contrast, Termination V reveals a lower C4-plant contribution than Marine Isotope Stage (MIS) 11c. The data exhibit a long-term trend, with a stepwise increase of the C4-plant contribution across interglacials MIS 11c, 9e, 7e and 1. We suggest that no substantial changes in humidity levels over glacial-interglacial cycles occurred facilitating a similar C3/C4-plant ratio for the LGM and the Holocene. Instead, deglacial sea-level rises caused an extensive development of floodplains and wetlands on the exposed continental shelf, providing habitats for the spread of C4 sedges and grasses. The progressive subsidence of Chinese coastal areas and the broadening of the continental shelf over the late Quaternary explains the nearly absence of C4 plant occurrence during Termination V and a gradual increase of the C4-plant contribution across interglacial peaks. Taken together, changes in coastal environments should be considered when interpreting marine-based vegetation reconstructions from subtropical Asia.

Coastal Environmental Change and the Salt Farmer Marginalization in Kusamba, Bali

The coastal environment in Klungkung Regency is undergoing rapid change as a result of the pace of development to serve the demands of the tourism industry, especially in the Nusa Penida islands, which has been designated as a Strategic Tourism Area. Changes in the coastal environment has led to the marginalization of some coastal residents, especially palung salt farmers on the Kusamba beach. This traditional salt production technology highly depends on the stability of the coastal environment, especially the availability of land on the coast. The development of community ports on the Kusamba coast and surrounding areas to support tourism development easily creates pressure for palung salt farmers. This is because the entire production process in the traditional salt is carried out on the coastline. By relying on literature studies and documents as well as experience doing fieldwork in the Kusamba pesisri, this article shows that the development of the people's port and the arrangement of the Kusamba coastal area has marginalized palung salt farmers. Marginalization that can be identified includes restrictions on access to land on the coast border, leading to increasingly limited production areas.

High-resolution records of growth temperature and life history of two Nacella limpet species, Tierra del Fuego, Argentina

Stable isotope ratios in patelloid limpets of the genus Patella have been established as proxies for coastal environmental change at sub-monthly resolution along the eastern North Atlantic and Mediterranean Sea. Nacella deaurata (Gmelin 1791) and N. magellanica (Gmelin 1791) are common intertidal species of patelloid limpets inhabiting the coast of Tierra del Fuego, Argentina/Chile and are commonly found in Holocene archaeological deposits. Here, we examine oxygen and carbon isotope ratios (δ18Oshell and δ13Cshell, respectively) of modern specimens of N. deaurata and N. magellanica to test the hypotheses that: 1) they form their shells in isotopic equilibrium with ambient water; and 2) prominent growth lines form annually. Based on growth margin analysis of δ18Oshell values, we identified a positive offset of 1.3 ± 0.4‰ (N. deaurata) and 1.3 ± 0.3‰ (N. magellanica) from expected equilibrium, similar to other patelloid limpets. Because the offset is relatively consistent between observed and expected values, it can be taken into account to reliably reconstruct growth temperature. Seawater temperature estimated from oxygen isotope time series data falls within the observed range. Thus, N. deaurata and N. magellenica shells serve as reliable proxy archives of seasonal variation in coastal seawater temperature. Time series of δ13Cshell values do not vary seasonally in all shells; hence, the influence on its variation requires further study. The timing of prominent growth lines contextualized by the δ18Oshell time series form twice a year and therefore cannot be used to estimate lifespan. Future isotopic analysis of archaeological Nacella shells can potentially provide much needed information about Holocene climate change at sub-monthly resolution from high-latitude South American locations, and contribute to our understanding of human behavior and human-climate interactions.

Observing Geomorphological Change on an Evolving Coastal Sand Dune Using SLAM-Based UAV LiDAR

Following over 20 years of manned airborne LiDAR in the remote sensing of geomorphological change in coastal environments, rapid advancements in unmanned aerial vehicle (UAV) technologies have expanded the possibilities of acquiring very high-resolution data efficiently over spatial-temporal scales not previously feasible. This study employed a new Simultaneous Localisation and Mapping (SLAM)–based LiDAR system (“Hovermap”) across a segment of coastal sand dune of Bribie Island, Queensland, Australia. The study area was identified by the local council as an area of interest over concern that continued erosion at an existing blowout could result in cutting off northern Bribie Island and adversely affect hydrodynamic processes of Pumicestone Passage, its shoreline, and its associated infrastructure. Here, we employed the Hovermap within a multi-temporal design in which four, quarterly, surveys undertaken over a 9-month period from July 2017 to April 2018. On the first survey, a Leica P40 (P40) terrestrial laser scanner (TLS) was also deployed across the study area to facilitate a performance comparison. Hovermap reported a mean point cloud density of 2532 ± 170 pts.·m-2, ground sample distance (GSD) of 0.02 ± 0.001 m, and RMSE of 0.050 ± 0.31 m relative to ground control points (GCPs). Three-dimensional mesh objects were derived from all point clouds obtained and evaluated in terms of elevation and slope with mesh-to-mesh deviations and volumetric change (cubature) analysis examined over consecutive surveys. The Hovermap closely matched results of the P40 with measures of elevation and slope differing by approximately 2% and 7%, respectively. Mean vertical deviation (0.01 ± 0.03 m) and cubature (~ 2.5 m3 net difference) results also showed close agreement. Due to stable wave conditions between the first three surveys, minimal changes in beach topography were observed, whilst pronounced erosion and scarping of the foredune were measured during the final survey. This erosion was evidenced from changes in mean elevation (− 16%), slope (+ 25%), and deviation (+ 86%) relative to the mean measurements over the first three survey dates. In addition, a net loss of approximately -1295 m3 of sand was measured between the final two survey dates (January–April 2018). This is supported by local marine weather data in which a significant increase in local wind speeds (ANOVA, F(1,180) = 6.257, p = 0.013) and wave heights (ANOVA F(1,180) = 41.769, p ≤ 0.001) were recorded over the same interval. The results presented here are first to demonstrate that UAV LiDAR performance was robust in a typical, moderate-energy, sandy beach and is suited for the detection and evaluation of coastal morphologic change at microspatial and temporal scales.

“The Languo of Flows”

Abstract“Flow” is a key concept in our era of liquid modernity, across a broad range of ecological, economic, and cultural discourses. In this essay, we examine the material flows integral to naturecultures through the specific case study of Seascale on the Cumbria coast in the UK. Through an analysis of cultural representations, we show the construction of Seascale as a seaside resort in the nineteenth and early twentieth centuries, and the rapid and irrevocable sinking of its cultural value since the commissioning of the nuclear power and reprocessing plant at Sellafield in 1947. By following the “flows” of pleasure, emotion, energy, and waste through Seascale, we explore the legacies of nuclear contamination for coastal communities, within a broader regime of the commodification of nature. This essay emerges from a transdisciplinary research project to investigate the cultural influences and impacts of ecosystem change in coastal environments around the Irish Sea. A collaboration between environmental humanities and ecological sciences, the project sought a materialist intervention in the conceptualization and practice of ecosystem assessment so as to capture and map a more inclusive and multidirectional sense of the flows that are integral to ecosystems, and to move beyond the limitations of dominant models of environmental stewardship. In contrast to the ways in which flow metaphors have been employed in contemporary economic and environmental discourse, the project attempts to analyze the material flows integral to naturecultures through particular places, perspectives, and agencies.

Coastal landscape evolution of Corsica island (W. Mediterranean): palaeoenvironments, vegetation history and human impacts since the early Neolithic period

A multi-proxy investigation of sediment cores has enabled us to reconstruct the coastal environmental evolution of East-Central Corsica (the sites of Saint Florent, Piantarella-Bonifacio and Palo-Solenzara) for the last 8000 years. The analytical methods comprise pollen (five original pollen diagrams), weight loss-on-ignition measurements, laser granulometry, and ostracod identification. In addition, 26 radiocarbon dates are used to provide a robust chronostratigraphy for the sedimentary sequences. The assessment of coastal landscape dynamics enables us to define the major morphological changes and to evaluate the complex interplay between climatic forcing and anthropogenic activity on the vegetation history of Corsica, within an archaeological context, since the early Neolithic period (∼7.4 cal kyr BP). The major findings are that the first farmers reached Corsica by sea, and they encountered a coastal environment mainly composed of freshwater ponds located close to the shoreline. This specific paleoenvironmental feature offered a favourable location for agriculture and for the development of permanent settlements where a subsistence economy was developed. Since the Middle Holocene, postglacial sea-level rise has caused major changes in local coastal environments, often characterized by salt intrusion into freshwater bodies. At the transition between the Mid and Late Holocene (∼4.0 cal kyr BP), an increase in both salinity and aridity caused substantial landscape changes, mainly characterized by a further expansion of saline marshland, mainly occupied by Chenopodiaceae. The results also provide new insights into the role of Erica in the original Holocene vegetation of Corsica. Our data clearly indicate that an Erica arborea - Quercus ilex forest transition occurred before 6.3 cal kyr BP, significantly earlier than previously proposed. Finally, the earliest evidence of cereal cultivation is at ∼7350 cal kyr BP, and in addition we are better able to constrain the role of humans in the landscape dynamics of Corsica since the early Neolithic.

Using traditional ecological knowledge to understand and adapt to climate and biodiversity change on the Pacific coast of North America

We investigate the perceptions and impacts of climate change on 11 Indigenous communities in Northern British Columbia and Southeast Alaska. This coastal region constitutes an extremely dynamic and resilient social-ecological system where Indigenous Peoples have been adjusting to changing climate and biodiversity for millennia. The region is a bellwether for biodiversity changes in coastal, forest, and montane environments that link the arctic to more southerly latitudes on the Pacific coast. Ninety-six Elders and resource users were interviewed to record Traditional Ecological Knowledge (TEK) and observations regarding weather, landscape, and resource changes, especially as concerns what we term Cultural Keystone Indicator Species (CKIS), which provide a unique lens into the effects of environmental change. Our findings show that Indigenous residents of these communities are aware of significant environmental changes over their lifetimes, and an acceleration in changes over the last 15–20 years, not only in weather patterns, but also in the behaviour, distributions, and availability of important plants and animals. Within a broader ecological and social context of dwelling, we suggest ways this knowledge can assist communities in responding to future environmental changes using a range of place-based adaptation modes.

Socio-ecological Mobility: A Research Strategy for a New Coastline

Persistent development, population pressures, and increasing natural hazards are unequivocally changing socio-ecological systems in the coastal zone. This essay provides direction and initiates scientific dialog on the potential role of mobility in adapting to natural and social changes in coastal environments. The essay identifies four key research areas on information needed to develop coastal management actions and policies that support and recognize socio-ecological coupling in coastal areas. The proposed research includes: (1) modeling localized scenarios that illustrate the tradeoffs associated with various sea level rise adaptation, (2) assessing and consolidating mobility terminology for different applications and contexts, (3) developing solutions to synchronize the co-migration of natural environments and built infrastructure, and (4) evaluating existing or creating new transparent, equitable, and sustainable policies and incentives to support socio-ecological mobility by using case studies and social science methods to understand how people make mobility decisions in different contexts.

Holocene coastal environmental changes and human occupation of the lower Hérault River, southern France

Sea-level rise, human impacts and climate change have deeply affected coastal environments during the Holocene. These forcing factors are studied using the Lower Hérault valley, which constitutes a very representative Mediterranean case study because of (i) its very early, intense and continuous land use since Neolithic times, and (ii) its sensitivity to sea-level rise and Mediterranean climate changes over a relatively small watershed. 34 cores and 61 AMS radiocarbon dates, associated with biological and geochemical analyses, have allowed us to precisely reconstruct the Holocene evolution of the lower valley. Until 6500 cal yr BP, a wave-dominated morphology and retrogradational dynamics were reconstructed. During this phase, ephemeral channels and successive river mouths formed and were rapidly submerged by sea-level rise. The progradational phase began after 6500 cal yr BP, and the alluvial plain gradually built seawards with the formation of a beachridge system outside the valley. Growth of the fertile alluvial plain was coeval with the development of Neolithic agriculture. This alluvial progradation gradually filled the estuary with advances of the mouths, several shallow lagoons and sandbar. The high density of information collected allows us to recognize, for the first time, a pronounced fluvial-dominated deltaic morphology, especially 3000 years ago, during the Bronze Age. Lagoonal and coastal shores were continually inhabited. Human land use continually adapted to geomorphological and environmental changes. Around 300 years ago, the delta shifted to a wave-dominated system.

A Study on Changes in Coastal Erosion Environment by Time Series Coastal Detection Using GIS

Jeong, H.Y., 2019. A study on changes in coastal erosion environment by time series coastal detection using GIS. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 331-335. Coconut Creek (Florida), ISSN 0749-0208.This paper identifies major coastal erosion factors for Hupo beach of the east coast of Korea where coastal erosion is serious, and looks into how beach erosion environment has changed through time series analysis (1970 - 2015). Aerial photographs of the beach by each time period were used to calculate the area of the beach, and analysis of correlation with identified factors on top of trend analysis were done to find and analyze major factors that have an impact on long-term changes in the beach. This paper is expected to contribute to identification of future coastal erosion factors, building-up and application of database, and policy-making to respond to changes in coastal erosion environment.

Holocene coastal environmental change and ENSO-driven hydroclimatic variability in East Asia

Understanding the past natural behavior of coastal hydroclimates at multi-centennial time scales is essential for planning coastal strategies in preparation for anticipated climate change. We investigated the elemental and isotopic features of 10-m-long coastal sedimentary cores from Goheung Bay located on the southern coast of Korea to extract such natural variability. Based on the relationships among total organic carbon (TOC), total sulfur (TS) content, and their isotopic values (δ13CTOC and δ34STS), we reconstructed the long-term coastal evolution in the area and compared this with the reported Holocene sea level change. Time series data of the titanium (Ti)/aluminum (Al) ratio, as a proxy for riverine terrigenous input, revealed a strong link to terrestrial plant contribution, as indicated by δ13CTOC variability, suggesting past hydroclimatic change in the study area. The short-term variability of Ti/Al ratios correlated well with flooding events reconstructed for the Nakdong River in Korea. Moreover, periods in which the Ti/Al ratio was higher corresponded to those of stronger El Niño Southern Oscillation (ENSO) activity, suggesting ENSO-driven hydroclimatic changes in southern Korea. Especially, the periods of higher Ti/Al ratios during the late Holocene corresponded to a higher frequency of typhoon-driven overwash events along the southwestern coast of Japan. These similarities suggest that past freshwater input events along the southern coast of Korea were influenced considerably by typhoon-driven heavy rains during stronger ENSO activity. Spectral analysis of the Ti/Al ratios revealed significant periodicities of 1550, 780, 140, 120 and 105 years, suggesting centennial to millennial-timescale variability in hydroclimatic change and typhoon activity over East Asia.

The order is rapidly fadin’

Purpose This paper reviews the relationship between property and the changing coastal environment. It looks at issues around the mismatch between the protection of private property rights implicit in our property law, which assumes stability and permanence, and the protection of public rights and environmental values expected of coastal land, which is increasingly vulnerable to climate change hazard. Issues of retreat from the coast, perhaps with compensation and incentives, will need to be dealt with. Design/methodology/approach New Zealand situations and examples are used to illustrate the conflicts between secure property rights and changing coastal land. Findings The effects of climate change on coastal land will be significant. This era of environmental degradation and climate change will require a significant re-ordering of property law. Changes in coastal land will require property owners to adapt their use and occupation of the coastal zone, if necessary by retreating. Similarly, local authorities will need to be proactive in planning for coastal land changes. Social implications Property will need to be re-imagined to support public and environmental goals for the coast. Originality/value This paper extends other discussions about how property law and the protection of property rights is a barrier to implementing climate change responses.

Validating an Operational Flood Forecast Model Using Citizen Science in Hampton Roads, VA, USA

Changes in the eustatic sea level have enhanced the impact of inundation events in the coastal zone, ranging in significance from tropical storm surges to pervasive nuisance flooding events. The increased frequency of these inundation events has stimulated the production of interactive web-map tracking tools to cope with changes in our changing coastal environment. Tidewatch Maps, developed by the Virginia Institute of Marine Science (VIMS), is an effective example of an emerging street-level inundation mapping tool. Leveraging the Semi-implicit Cross-scale Hydro-science Integrated System Model (SCHISM) as the engine, Tidewatch operationally disseminates 36-h inundation forecast maps with a 12-h update frequency. SCHISM’s storm tide forecasts provide surge guidance for the legacy VIMS Tidewatch Charts sensor-based tidal prediction platform, while simultaneously providing an interactive and operationally functional forecast mapping tool with hourly temporal resolution and a 5 m spatial resolution throughout the coastal plain of Virginia, USA. This manuscript delves into the hydrodynamic modeling and geospatial methods used at VIMS to automate the 36-h street-level flood forecasts currently available via Tidewatch Maps, and the paradigm-altering efforts involved in validating the spatial, vertical, and temporal accuracy of the model.

Modelling Actual and Future Seawater Intrusion in the Variconi Coastal Wetland (Italy) Due to Climate and Landscape Changes

Coastal freshwater resources are commonly under high risk of being contaminated from seawater. The main processes that affect seawater intrusion are groundwater overexploitation, land use change, and climate change effects. In this context coastal lagoons represent the more sensitive environments prone to seawater intrusion. Numerical modelling is a useful tool to understand and predict seawater intrusion. In this study, a three-dimensional SEAWAT model is employed to simulate the seawater intrusion to coastal aquifers of Variconi Oasis (Italy). The present simulation was divided into a calibration and a validation model, then the model was used to predict the salinization trend up to 2050. Results show the role of the sea in salinizing the beach front, while the retrodunal environment is characterized by transitional environments. Future seawater intrusion scenarios considering only climate data showed no significative differences in respect to the actual situation. The same happens considering also a low sea level rise prediction. On the contrary, the worst scenario (high sea level rise prediction), depicts a quite different situation, with a saline intrusion in the Variconi oasis that will severely affect the fragile transitional ecosystem. This modelling framework can be used to quantify the effects of climate changes in similar coastal environments.

Effects of Seawater Acidification on Early Development of Clam Cyclina sinensis

Anthropogenic emission of atmospheric carbon dioxide (CO2) has led to a rapid increase in atmospheric CO2 concentration. Increasing atmospheric CO2 can reduce seawater pH and carbonate ions, which may adversely affect the survival of the larvae of calcareous animals. Cyclina sinensis is a commercially and ecologically important species in several Asian countries. Living in coast shallow waters, this species has experienced the coastal environmental changes frequently throughout its life cycle. In this study, we simulated possible future seawater pH values including 8.2, 7.8 and 7.4 and examined the effects of ocean acidification on the early development of C. sinensis. Clam embryos were incubated for 48 h (2 d) in control and high-CO2 seawater to compare embryogenesis, larval growth and swimming behavior. Fertilization rate was quite sensitive to pH, and moderate acidification could induce a significant decrease in fertilization rate. However, only extreme acidification could bring significant negative effect to hatching rate, body size, and average path velocity of trochophora. Moreover, with seawater acidification, C. sinensis needs much more time to reach the same developmental stage, which increases the risk of larva survival. Together with recent studies demonstrating negative impacts of high CO2 on fertilization and larva swimming behavior, the results imply a future decrease of C. sinensis populations in oceans if its acclimation to the predicted environmental alteration does not occur.

Changes in mangrove vegetation, aquaculture and paddy cultivation in the Mekong Delta: A study from Ben Tre Province, southern Vietnam

In this paper, we analyzed the changes in mangrove forests along the coastal districts of Ben Tre Province in Mekong Delta, in southern Vietnam from 1998 to 2015 using Landsat image series (TM and OLI) using vegetation and water indices, and field data. Decadal changes in aquaculture ponds and area of rice crops were also estimated using satellite and field data in order to understand the influence of intensive aquaculture on mangrove deforestation and agriculture in this region. Furthermore, predictions have been made on the changes in mangrove forests, rice crops and aquaculture ponds in case of 1 m and 2 m sea level rise. About 52.5% of the mangrove forests were cleared between 1998 and 2015 for aquaculture and infrastructure developments in Ben Tre during the study period. Thanh Phu District showed highest loss of mangrove forests (59.3%) and increase in the area covered by aquaculture ponds (120%) during this period. Overall reduction in the rice crops areas in Ben Tre was 23.4% whereas this was 31.5% in the coastal districts due to the conversion of freshwater rice fields into brackish shrimp ponds. It is estimated that a 1 m rise in the current sea level would clear 45.2% of the remaining mangrove forests, 60.9% of the current areas planted with rice, 65% of the aquaculture ponds and 46% of the entire province would be under the water. This study shows a clear picture of the coastal environmental changes going on in the Mekong Delta of Vietnam.