Sandy beaches at the brink

Sandy beaches line most of the world's oceans and are highly valued by society: more people use sandy beaches than any other type of shore. While the economic and social values of beaches are generally regarded as paramount, sandy shores also have special ecological features and contain a distinctive biodiversity that is generally not recognized. These unique ecosystems are facing escalating anthropogenic pressures, chiefly from rapacious coastal development, direct human uses — mainly associated with recreation — and rising sea levels. Beaches are increasingly becoming trapped in a 'coastal squeeze' between burgeoning human populations from the land and the effects of global climate change from the sea. Society's interventions (e.g. shoreline armouring, beach nourishment) to combat changes in beach environments, such as erosion and shoreline retreat, can result in severe ecological impacts and loss of biodiversity at local scales, but are predicted also to have cumulative large-scale consequences worldwide. Because of the scale of this problem, the continued existence of beaches as functional ecosystems is likely to depend on direct conservation efforts. Conservation, in turn, will have to increasingly draw on a consolidated body of ecological theory for these ecosystems. Although this body of theory has yet to be fully developed, we identify here a number of critical research directions that are required to progress coastal management and conservation of sandy beach ecosystems.     

Effects of Beach Nourishment on Sea Turtles: Review and Research Initiatives

Beach nourishment is an engineering solution to erosion of beaches. As in any restoration project, the goals of beach nourishment are the restoration of habitat to promote survival of plants and animals and to maintain aesthetically pleasing sites for humans. Unfortunately, beach nourishment sometimes alters parameters of the natural beach, decreasing the reproductive success of sea turtles. Engineers have recognized this problem and are working to improve nourishment practices. Biologists must specify problems incurred by sea turtles as a result of beach nourishment so that they may be addressed. A review of the literature on sea turtles and beach nourishment found certain problems repeatedly identified. For nesting females, characteristics induced by nourishment can cause (1) beach compaction, which can decrease nesting success, alter nest-chamber geometry, and alter nest concealment, and (2) escarpments, which can block turtles from reaching nesting areas. For eggs and hatchlings, nourishment can decrease survivorship and affect development by altering beach characteristics such as sand compaction, gaseous environment, hydric environment, contaminant levels, nutrient availability, and thermal environment. Also, nests can be covered with excess sand if nourishment is implemented in areas with incubating eggs. The extent and implication of each problem are discussed, and future research initiatives are proposed.     

Responses of Dune Plant Communities to Continental Uplift from a Major Earthquake: Sudden Releases from Coastal Squeeze

Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5º S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems.     

An integrated model of real estate market responses to coastal flooding

Understanding and improving how humans adapt to climate change are priorities in our research community, and coastal settlements are good places to study adaptation. Severe storm events and sea‐level rise are threatening coastal communities with increasing levels of flood damage. Because ownership of coastal assets is distributed among many private and public actors, both individual property owners and public officials must take adaptive actions. This paper introduces an integrated agent‐based and hedonic pricing modeling system to simulate coastal real estate market performance under non‐equilibrium conditions that reflect the effects of storm events. The modeling system, which is used for policy analysis, is calibrated to conditions in two towns in Monmouth County, New Jersey, USA, which were badly damaged by Hurricane Sandy in 2012. The key findings are that (a) coastal real estate markets capitalize flood risk into property values but this discount diminishes rapidly as time passes between storm events, and (b) there is a distinct equity versus efficiency tradeoff in designing public policies to reduce the cost to society of coastal flooding. Stringent regulation of building practices reduces flood damage but drives away poorer home buyers and owners, whereas informational and incentive‐based policies are fairer but less effective. Hands‐off, market‐based retreat from risky areas is socially costly but allows less wealthy people to remain at the shore, albeit in vulnerable situations. Managed retreat should emphasize improved recreational access to coastal amenities while discouraging people from living there.     

Estimating the Effect of Beach Nourishment on Caretta caretta (Loggerhead Sea Turtle) Nesting

Caretta caretta (loggerhead sea turtle) nesting activity was recorded daily during three seasons prior to and two seasons immediately following a beach nourishment (replenishment) project in Palm Beach County, Florida. Surveys were done at the nourished beach (Jupiter/Carlin) and at two natural beaches (Juno and Tequesta). The size of the nourishment effect on nesting activity was estimated using Before‐After‐Control‐Impact Paired Series (BACIPS) models. Nesting declined by 4.4 to 5.4 nests km ^{? 1} day ^{? 1} on the nourished beach compared to the two natural beaches in the first season after nourishment. At the same time, false crawls (FC, non‐nesting crawls) increased by 5.0 to 5.6 FC km ^{? 1} day ^{? 1} on the nourished beach. In the second season following nourishment, nesting was reduced by 0.5 to 1.6 nests km ^{? 1} day ^{? 1} on the nourished beach compared to the two natural beaches. The increase in false crawl frequency in the second season following nourishment was 0.7 to 0.9 FC km ^{? 1} day ^{? 1}.These results suggest that beach nourishment significantly decreased loggerhead sea turtle nesting during the first season following the project. However, the size of the effect, in terms of nesting frequency and false crawl frequency, was much reduced by the second season following nourishment.     

Natural Shorelines Promote the Stability of Fish Communities in an Urbanized Coastal System

Habitat loss and fragmentation are leading causes of species extinctions in terrestrial, aquatic and marine systems. Along coastlines, natural habitats support high biodiversity and valuable ecosystem services but are often replaced with engineered structures for coastal protection or erosion control. We coupled high-resolution shoreline condition data with an eleven-year time series of fish community structure to examine how coastal protection structures impact community stability. Our analyses revealed that the most stable fish communities were nearest natural shorelines. Structurally complex engineered shorelines appeared to promote greater stability than simpler alternatives as communities nearest vertical walls, which are among the most prevalent structures, were most dissimilar from natural shorelines and had the lowest stability. We conclude that conserving and restoring natural habitats is essential for promoting ecological stability. However, in scenarios when natural habitats are not viable, engineered landscapes designed to mimic the complexity of natural habitats may provide similar ecological functions.     

Multi-level assessment of ecological coastal restoration in South Texas

Adaptive management can be a very useful tool for assessing and improving coastal ecological engineering restoration projects. A shoreline restoration project using ecological engineering approaches to mitigate coastal erosion was developed and implemented in 2003 at Loyola Beach, Baffin Bay, TX. The project incorporated riprap, fiber matting, geotextile, and vegetation as an alternative to conventional hard structures for erosion control. As part of the restoration expansion, a detailed evaluation of the previous project was completed at several levels, including the landscape, geotechnical design, environmental and ecological considerations, and social and economic factors. The findings indicated that the vegetation and its underlying geotechnical integrity have played an important role in erosion mitigation. Overall the project was successful in the protection of the shoreline and was shown to be more ecologically beneficial than other hard structures. Based on the preliminary success of the initial project, the restoration techniques were adapted for another beach extension to the west. The assessment did reveal some weaknesses in the original project design including the need for more substantial toe protection and periodic maintenance requirements. Based on these assessments, some additional new methods for the restoration extension were proposed and implemented. The broader applicability of this restoration approach outside the local region has been presented through several outreach activities and delivered to coastal planners and land owners throughout the Texas Coastal Bend and Northern Mexico.     

海岸线变化研究综述

受全球及海岸带区域环境过程与人类活动的综合影响,海岸线发生剧烈的变化,对生态、环境及经济社会的影响不容忽视,海岸线变化相关研究因此得到普遍的关注。在讨论海岸线的定义和分类的基础上,介绍岸线信息提取的方法与技术,总结国内外海岸线变化的特征、机制与影响方面研究的进展,并指出未来研究的趋势,包括:对海岸线变化过程进行动态监测仍将是普遍关注的研究重点之一;对海岸线变化特征、规律与机理的认识已经日益深化,基于大量高精度数据和机理模型的研究已成为热点和前沿问题;针对不同的海岸带区域,聚焦海岸线变化的原因和机制及其对环境和生态的影响,以及不同区域之间的相互联系与影响特征,这将是未来研究的重点之一;中国海岸线变化的独特性、复杂性突出,促进和支撑中国的海岸带综合管理实践,提高决策者与管理者对岸线变化所带来的灾害风险的重视,为中国海岸带的科学规划与发展提供依据,这应该是我国海岸线变化研究的重要目标。     

183 The Environmental Impacts of Harvesting Beach‐Cast Seaweeds

Until recently the commercial collection of beach‐cast seaweeds in New Zealand was prohibited but the legislation has recently been amended to allow permitting of this activity. This review collates existing information on the role of beach‐cast seaweed in coastal ecosystems to describe the nature and extent of the effects that commercial removals of beach cast seaweed may have on the marine environment. It outlines the amount of beach‐cast seaweed available for harvest in New Zealand and the fate of seaweed when not collected; reviewing current information on the importance of beach‐cast seaweeds and its inhabitants on: feeding and nesting shorebirds, and nutritional contribution of seaweed inhabitants to nearshore coastal ecosystems when seaweed is washed back into the sea It also identifies key research gaps related to any environmental impacts that the removal of beach cast seaweed might have.     

Shoreline changes in a rising sea level context: The example of Grande Glorieuse,Scattered Islands,Western Indian Ocean

This paper provides baseline data on absolute and relative sea level variations and shoreline changes in the Scattered Islands region of the Indian Ocean, based on aerial image analysis, satellite altimetry and field observations and in situ measurements from the 2009 and 2011 TAAF scientific expeditions. The analysis shows the importance of regular observations and monitoring of these islands to better understand reef island responses to climate stressors. We show that Grande Glorieuse Island has increased in area by 7.5 ha between 1989 and 2003, predominantly as a result of shoreline accretion: accretion occurred over 47% of shoreline length, whereas 26% was stable and 28% was eroded. Topographic transects and field observations show that the accretion is due to sediment transfer from the reef outer slopes to the reef flat and then to the beach. This accretion occurred in a context of sea level rise: sea level has risen by about 6 cm in the last twenty years and the island height is probably stable or very slowly subsiding. This island expansion during a period of rising sea level demonstrates that sea level rise is not the primary factor controlling the shoreline changes. This paper highlights the key role of non-climate factors in changes in island area, especially sediment availability and transport. We also evidence rotation of the island, underscoring the highly dynamic nature of reef islands.     

Coastal dynamics and wetlands stability. The Ebro delta case

Coastal wetland stability and structure can be significantly affected by littoral processes when they are close to the shoreline. Thus, under certain conditions, the combination of shoreline dynamics and direct wave action during storms can influence the stability of marshes and vegetation community composition. This interaction between littoral dynamics and coastal wetlands is illustrated by analysing processes taking place in the Buda Island (Ebro delta, NW Spain), where a coastal lagoon very close to a retreating shoreline exists. Two main time scales have been found to be relevant for interaction of coastal processes with ecosystem dynamics, the decadal and episodic scales. The decadal scale determines the average trend in beach width and directly controls the potential loss of wetland surface. The episodic scale is linked to the occurrence of wave and storm surge events and it determines a pulsing stress in the ecosystem through flooding, being key parameters to determine their direct influence the intensity and repetition of these events.     

Comparative study of two largely infilled estuaries: The Eden Estuary (Scotland) and the Ria de Foz (Spain)

Two small estuaries, the Eden Estuary of eastern Scotland and the Ria de Foz of north west Spain, are compared. The former was glaciated during the Pleistocene, the latter was not. These water bodies are macrotidal, of similar size, entrance morphology and advanced state of sedimentary infill. There are, however, major differences in their sedimentary dynamics partly as a result of anthropogenic interference. A training wall partially confines the main channel of the Ria de Foz, whereas the Eden Estuary lacks comparable structures. Prior to the extension of the Foz wall, the rate of migration of a spit at the mouth of the ria was up to one order of magnitude greater than that of a similar spit in the Eden Estuary. Following completion of the wall, the rate of spit erosion in the Ria de Foz increased to two orders of magnitude greater than that of natural processes in the Eden. A beach nourishment scheme at Foz, relocating sediment deposited within the Ria, has succeeded in stabilising the spit and substantially reducing erosion. Relative stability of land and sea may have existed over the last 5,000 years at Foz but not at the mouth of the Eden, where isostatic uplift has exceeded sea level rise. The requisite stability for complete sedimentary infill at Foz may not exist owing to the predicted worldwide rise of sea level due to global warming. The rise of sea and land levels around the Eden Estuary are now believed to be counterbalanced, providing the necessary geological conditions for complete sedimentary infill.     

From grey to green: Efficacy of eco‐engineering solutions for nature‐based coastal defence

Climate change is increasing the threat of erosion and flooding along coastlines globally. Engineering solutions (e.g. seawalls and breakwaters) in response to protecting coastal communities and associated infrastructure are increasingly becoming economically and ecologically unsustainable. This has led to recommendations to create or restore natural habitats, such as sand dunes, saltmarsh, mangroves, seagrass and kelp beds, and coral and shellfish reefs, to provide coastal protection in place of (or to complement) artificial structures. Coastal managers are frequently faced with the problem of an eroding coastline, which requires a decision on what mitigation options are most appropriate to implement. A barrier to uptake of nature‐based coastal defence is stringent evaluation of the effectiveness in comparison to artificial protection structures. Here, we assess the current evidence for the efficacy of nature‐based vs. artificial coastal protection and discuss future research needs. Future projects should evaluate habitats created or restored for coastal defence for cost‐effectiveness in comparison to an artificial structure under the same environmental conditions. Cost‐benefit analyses should take into consideration all ecosystem services provided by nature‐based or artificial structures in addition to coastal protection. Interdisciplinary research among scientists, coastal managers and engineers is required to facilitate the experimental trials needed to test the value of these shoreline protection schemes, in order to support their use as alternatives to artificial structures. This research needs to happen now as our rapidly changing climate requires new and innovative solutions to reduce the vulnerability of coastal communities to an increasingly uncertain future.     

The future of the northeast Atlantic benthic flora in a high CO2 world

Seaweed and seagrass communities in the northeast Atlantic have been profoundly impacted by humans, and the rate of change is accelerating rapidly due to runaway CO₂ emissions and mounting pressures on coastlines associated with human population growth and increased consumption of finite resources. Here, we predict how rapid warming and acidification are likely to affect benthic flora and coastal ecosystems of the northeast Atlantic in this century, based on global evidence from the literature as interpreted by the collective knowledge of the authorship. We predict that warming will kill off kelp forests in the south and that ocean acidification will remove maerl habitat in the north. Seagrasses will proliferate, and associated epiphytes switch from calcified algae to diatoms and filamentous species. Invasive species will thrive in niches liberated by loss of native species and spread via exponential development of artificial marine structures. Combined impacts of seawater warming, ocean acidification, and increased storminess may replace structurally diverse seaweed canopies, with associated calcified and noncalcified flora, with simple habitats dominated by noncalcified, turf‐forming seaweeds.     

Picturing beach erosion and deposition trends using PSInSAR: an example from the non-barred southern west coast of India

Coastal dynamics can rapidly alter beach morphology. In some places, such as the non-barred southern west coast of India, studying changes to beach morphology is a relatively arduous task. Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR), a remote sensing technique that utilizes stacks of radar images for accurate long-term monitoring of ground features, allows for detailed observations of coastal morphodynamics. Twenty-two single look complex (SLC) synthetic aperture radar (SAR) Sentinel-1A images, acquired from 4 March 2016 to 3 June 2017, are used to monitor geomorphological processes such as coastal erosion and deposition. Ground deformation measurements from PSInSAR processing shows the coast stretching?~?70 km between Thaickal and Munambam is highly dynamic, characterized by phases of erosion and deposition. The highest negative displacement of ? 24.9 mm at Thaickal versus the?+?7.6 mm at Chellanam in the north show the co-existing milieus of erosion and deposition. PSInSAR results concur with corresponding Google Earth images. In addition, beach sediment texture and scanning electron microscope grain micro-texture in the beach segment further corroborate temporal phases of erosion and deposition. Two locations are identified as typical erosional sites, while one location typified deposition. Erosion and deposition or rebuilding of beaches, usually correspond respectively with the onset and offset of SW monsoon wave climate in the Arabian Sea. When zones of deposition are mainly located in the proximity of river and/or lake inlets, stretches characterized by erosion are distal to inlets. Linear regression analyses of displacement–time series plots were used to identify general erosion or depositional regimes along beach segments. Results from this study illustrate how PSInSAR is a capable and reliable processing tool for monitoring temporal phases of coastal morpho-dynamics.

     

185 Phytate Utilization by Tetrahymena

Until recently the commercial collection of beach-cast seaweeds in New Zealand was prohibited but the legislation has recently been amended to allow permitting of this activity. This review collates existing information on the role of beach-cast seaweed in coastal ecosystems to describe the nature and extent of the effects that commercial removals of beach cast seaweed may have on the marine environment. It outlines the amount of beach-cast seaweed available for harvest in New Zealand and the fate of seaweed when not collected; reviewing current information on the importance of beach-cast seaweeds and its inhabitants on: feeding and nesting shorebirds, and nutritional contribution of seaweed inhabitants to nearshore coastal ecosystems when seaweed is washed back into the sea It also identifies key research gaps related to any environmental impacts that the removal of beach cast seaweed might have.     

Non‐native mangroves support carbon storage,sediment carbon burial,and accretion of coastal ecosystems

Mangrove forests play an important role in climate change adaptation and mitigation by maintaining coastline elevations relative to sea level rise, protecting coastal infrastructure from storm damage, and storing substantial quantities of carbon (C) in live and detrital pools. Determining the efficacy of mangroves in achieving climate goals can be complicated by difficulty in quantifying C inputs (i.e., differentiating newer inputs from younger trees from older residual C pools), and mitigation assessments rarely consider potential offsets to CO₂ storage by methane (CH₄) production in mangrove sediments. The establishment of non‐native Rhizophora mangle along Hawaiian coastlines over the last century offers an opportunity to examine the role mangroves play in climate mitigation and adaptation both globally and locally as novel ecosystems. We quantified total ecosystem C storage, sedimentation, accretion, sediment organic C burial and CH₄ emissions from ~70 year old R. mangle stands and adjacent uninvaded mudflats. Ecosystem C stocks of mangrove stands exceeded mudflats by 434 ± 33 Mg C/ha, and mangrove establishment increased average coastal accretion by 460%. Sediment organic C burial increased 10‐fold (to 4.5 Mg C ha^?1 year^?1), double the global mean for old growth mangrove forests, suggesting that C accumulation from younger trees may occur faster than previously thought, with implications for mangrove restoration. Simulations indicate that increased CH₄ emissions from sediments offset ecosystem CO₂ storage by only 2%–4%, equivalent to 30–60 Mg CO₂‐eq/ha over mangrove lifetime (100 year sustained global warming potential). Results highlight the importance of mangroves as novel systems that can rapidly accumulate C, have a net positive atmospheric greenhouse gas removal effect, and support shoreline accretion rates that outpace current sea level rise. Sequestration potential of novel mangrove forests should be taken into account when considering their removal or management, especially in the context of climate mitigation goals.     

Oyster reefs as natural breakwaters mitigate shoreline loss and facilitate fisheries

Shorelines at the interface of marine, estuarine and terrestrial biomes are among the most degraded and threatened habitats in the coastal zone because of their sensitivity to sea level rise, storms and increased human utilization. Previous efforts to protect shorelines have largely involved constructing bulkheads and seawalls which can detrimentally affect nearshore habitats. Recently, efforts have shifted towards "living shoreline" approaches that include biogenic breakwater reefs. Our study experimentally tested the efficacy of breakwater reefs constructed of oyster shell for protecting eroding coastal shorelines and their effect on nearshore fish and shellfish communities. Along two different stretches of eroding shoreline, we created replicated pairs of subtidal breakwater reefs and established unaltered reference areas as controls. At both sites we measured shoreline and bathymetric change and quantified oyster recruitment, fish and mobile macro-invertebrate abundances. Breakwater reef treatments mitigated shoreline retreat by more than 40% at one site, but overall vegetation retreat and erosion rates were high across all treatments and at both sites. Oyster settlement and subsequent survival were observed at both sites, with mean adult densities reaching more than eighty oysters m(-2) at one site. We found the corridor between intertidal marsh and oyster reef breakwaters supported higher abundances and different communities of fishes than control plots without oyster reef habitat. Among the fishes and mobile invertebrates that appeared to be strongly enhanced were several economically-important species. Blue crabs (Callinectes sapidus) were the most clearly enhanced (+297%) by the presence of breakwater reefs, while red drum (Sciaenops ocellatus) (+108%), spotted seatrout (Cynoscion nebulosus) (+88%) and flounder (Paralichthys sp.) (+79%) also benefited. Although the vertical relief of the breakwater reefs was reduced over the course of our study and this compromised the shoreline protection capacity, the observed habitat value demonstrates ecological justification for future, more robust shoreline protection projects.     

Assess the human and environmental vulnerability for coastal hazard by using a multi-criteria decision analysis

This study provides an integrated approach using geographical information system (GIS) based on a multi-criteria approach (MCDA) to assess coastal vulnerability, resulting from human activity, population density, erosion, and climate change-induced sea level rise. A coastal vulnerability index (CVI) for erosion and floods was calculated and mapped (～24 km in length; ～400 m in width, and 11.47 km² in surface) for the lagoon barrier of Nador located on the Mediterranean coast of Morocco. Results suggest that 54% (～13 km) of the shoreline is moderately vulnerable, while 42% (～10 km) is highly vulnerable and only 4% (1 km) present a low vulnerability. The vulnerability map of the socio-economic activities indicates that most wetlands and forest areas 83% (～31 ha) and 50% (～440 ha) respectively, present low vulnerability. 52% percent of artificial areas (～23 ha), 73% of agricultural land (～128 ha), and 41% of natural areas (～363 ha) present moderate vulnerability. However, the level of vulnerability of the remaining artificial and agricultural areas classifies from high to very high. The north-western sector was classified as the most vulnerable area, characterized by an erosion (?0.6 m/yr to ?1.20 m/yr) for 70% of this area, while the south-eastern part shows a low to moderate vulnerability marked by an erosion (?0.1 m/yr to ?1m/yr) for 40% of this area. Coastal vulnerability maps have potential as decision tools to prepare and respond to sea level rise, and identify exposed coastal zones, as such contributing to national climate action and disaster risk reduction sustainable development goals (goals 13 and 11, respectively).