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Chen, L. and Wang, W., 2017. Ecophysiological responses of viviparous mangrove Rhizophora stylosa seedlings to simulated sea-level rise. As the only forests situated at the transition between land and sea, mangrove forests constitute one of the first ecosystems vulnerable to rising sea level. When sea-level rises, plants are exposed to increased salinity, as well as tidal flooding. The responses of mangrove forests to changing sea levels depend on the synergistic effects of tidal flooding and salinity on plants, especially plants at the seedling stage. Therefore, the aims of this paper were to assess the ability of viviparous mangrove Rhizophora stylosa Griff. seedlings to withstand tidal flooding given different seawater salinities, as well as to investigate the effects of tidal flooding and salinity on plant growth. To accomplish this, a mesocosm experiment was initiated to examine the synergistic effects of tidal flooding and salinity on the growth and physiology of R. stylosa samples subjected to seven tidal flooding times (0, 2, 4, 6, 8, 10, and 12 h simulated semidiurnal tide, twice daily) and two levels of water salinity (15 and 30 PSU [practical salinity units]) over the course of 100 days. Throughout the experimental period, R. stylosa seedlings exhibited the traits of flood-tolerant plants, including such mechanisms as high stem growth rate and leaf assimilation rate, as well as efficient utilization of carbohydrate reserves stored in hypocotyls of seedlings. The growth and physiological responses of R. stylosa seedlings were significantly affected by both salinity and flooding time. However, elevated salinity had less effect on growth and metabolism than simulated sea-level rise by the increase of flooding time. From these results, it can be concluded that R. stylosa at higher salinity exhibits competitive dominance and thus good adaptation of seedlings to future predicted rise in sea level, which could presumably result in niche shifting. [ABSTRACT FROM AUTHOR]

Strachan, K.L.; Hill, T.R.; Finch, J.M.; Barnett, R.L., and Frenzel, P., 2017. Distribution of salt-marsh foraminifera in two South African estuaries and the application as sea-level indicators. The global mean sea level is rising as a result of climate change and is likely to affect millions of people. It is essential to understand and quantify regional relative sea-level variability to be able to predict future changes. Proxy evidence is necessary for extending our understanding of past sea-level changes beyond the industrial era, and salt-marsh foraminifera have become an important tool for reconstructing late Holocene sea-level changes. In South Africa, little is known regarding the distribution of salt-marsh foraminifera and their use as sea-level indicators, thereby limiting their application in sea-level research. This study therefore describes the distribution of living and dead surface foraminifera from two study sites along the SE South African coastline. The full surface dataset has been compiled from 139 samples that are used to describe the contemporary distribution of salt-marsh foraminifera. Cluster analysis is used to define four biozones; high marsh, middle marsh, low marsh, and mudflats. In the high marsh, where environmental conditions reach the survival threshold, a greater abundance of agglutinated foraminifera occurs. In the low-marsh zone, where subaerial exposure is restricted and environmental conditions are usually stable, a greater diversity of calcareous species occurs. The tidal mudflats have the highest diversity of calcareous assemblages with some agglutinated taxa present. Distributions of living foraminiferal populations are similar to the population distributions of dead foraminifera at both sites in the low-marsh and mudflat zones. In the high-marsh zones, however, the living-to-dead ratio and distributions are different, which could be a result of different influences of environmental variables along with seasonal variations. This study provides insights into foraminiferal distributions along the SE coastline of South Africa, which will be useful for interpreting late Holocene sea-level changes. [ABSTRACT FROM AUTHOR]

Stephenson, W.J. and Abazović, A. 2016. Measuring Coastal Boulder Movement Under Waves Using Tri-Axial Accelerometers. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 607-611. Coconut Creek (Florida), ISSN 0749-0208. Boulder entrainment under tsunami or storm wave conditions has been a topic of interest among coastal geomorphologists for the last 25 years. Efforts have been directed to understanding the dynamic conditions under which boulder entrainment occurs and in particular the energy levels required to move boulders of specific sizes. Recent focus on storm waves has highlighted the complexity of the process and that more energetic tsunami waves are not always needed to move larger boulders. Consequently attempts have been made to develop better empirical equations to predict wave height or flow velocity and differentiate between storm waves and tsunami. However, data collection methods are restricted to hindcasting flow conditions based on boulder size, the chosen empirical equations and assumptions regarding historical storm or tsunami events. Significant advances could be made using real time entrainment data of boulder movement alongside flow conditions. This is particularly true if movement type, e.g. suspension, rolling or sliding can be distinguished. This paper demonstrates the use of small and inexpensive tri-axial accelerometers manufactured by Gulf Coast Data Concepts. The accelerometers were placed in PVC water tight housing then located in holes cored into boulders and deployed in conjunction with wave pressure transducers on the shore platform. Movement of 4 boulders were observed by logging real-time accelerations during a 5 day deployment. Preliminary data demonstrated that boulders rolled and moved up to 3 m in a westerly direction, while wave heights were less than 0.7 m, demonstrating of the viability of this technique. [ABSTRACT FROM AUTHOR]

Poate, T.G.; Masselink, G; Austin, M.; Dickson, M.E., and Kench, P., 2016. Observations of Wave Transformation on Macro-Tidal Rocky Platforms. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 602-606. Coconut Creek (Florida), ISSN 0749-0208. Correctly predicting the transformation of ocean waves across rocky platforms has direct implications for cliff stability modelling, coastal defences and long-term coastal evolution. Wave transformation across rocky intertidal platforms is dependent on the morphological characteristics of the platform, including platform width, slope and roughness, and forcing characteristics, including wave and tide conditions. In this paper we present early observations from four field studies providing detailed measurements of wave processes across contrasting rocky platform sites with wave conditions between Hs = 0.5 m and Hs = 1.9 m, water depths between h = 0.5 m and h = 6.8 m and variable platform morphology. Results show that the relative wave height in the surf zone H/ h is generally larger than in previous studies ( H/ h is c. 0.6, instead of 0.3-0.5) and wave dissipation greater for sites with considerable roughness. [ABSTRACT FROM AUTHOR]

Swirad Z.M.; Rosser, N.J.; Brain, M.J., and Vann Jones, E.C., 2016. What controls the geometry of rocky coasts at the local scale? In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 612-616. Coconut Creek (Florida), ISSN 0749-0208. There is a need to understand the controls on rocky coastal form in order to predict the likely response to climate changes and sea-level rise. Spatial variations in coastal geometry result from inheritance and contemporary processes, notably erosive wave intensity and rock resistance. We studied a 4.2 km long section of coastline (Staithes, North Yorkshire, UK) using LiDAR point cloud data and ortho-photographs. We represented the coast as a series of densely-spaced (25 m) and resampled (0.2 m) 2D cross-sections. GIS-based statistical analysis allowed us to identify relationships between coastal morphology, geology (lithology and rock structure) and wave intensity. We found the following statistically-significant relationships: 1) more intensive waves and weaker rocks are associated with steeper shore platforms, 2) higher platforms and cliff toes are associated with weaker and more variable rocks, and 3) surface roughness increases with greater wave intensity, decreased density of discontinuities and decreased variability of intact rock hardness. However, these relationships are weak, which suggests the potential role of coastal inheritance and/or the need to better represent rock resistance in coastal models. [ABSTRACT FROM AUTHOR]

Burvingt, O.J.P.; Masselink, G., Russell, P., and Scott, T. 2016. Beach response to consecutive extreme storms using LiDAR along the SW coast of England. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1052 - 1056. Coconut Creek (Florida), ISSN 0749-0208. On the south west coast of England, the 2013/14 winter has been the most energetic period over the past 60 years, counting over 22 storms with recorded wave heights exceeding 10 meters. Pre- and post-storm aerial LiDAR surveys have been carried out by the Environmental Agency along the entire SW coastline. A total of 157 beaches have been selected from this dataset and morphological changes over the stormy period have been calculated and studied by processing the LiDAR data. This analysis shows the varying response of the beaches to the extreme storms and highlights two mechanisms involved in sediment transport. The results show that North coast beaches exposed to the main storm waves eroded, losing sediment offshore by cross-shore transport processes. Conversely, on the South coast beaches, where wave approach was more oblique, sediment was mainly transported along-shore resulting in beach rotation. [ABSTRACT FROM AUTHOR]

Kakroodi, A.A.; Kroonenberg, S.B.; Goorabi, A., and Yamani, M., 2014. Shoreline response to rapid 20th century sea-level change along the Iranian Caspian Coast. The Caspian Sea, the largest lake in the world, is characterized by rapid sea-level changes. This provides a real physical model of coastal response to rapid sea-level change in a period of just a few years, which might take a millennium along oceanic coasts. Between 1929 and 1995, the Caspian sea level experienced the last cycle, with a range of ±3 m. This caused disastrous effects along the coast and destroyed many buildings, roads, farms, and other human property. During the preceding 48 years of sea-level fall, a large area of the sea bottom emerged, which was then used for the development of residential zones. That area had to be abandoned when sea level rose by almost 3 m in a period of 18 years. With the use of LANDSAT data, we calculated total shoreline shifts in 22 littoral cells, each cell containing three transects over a 3-km distance. Both landward and seaward shifts occur during rapid sea-level rise between 1977 and 2001. [ABSTRACT FROM AUTHOR]

Kakroodi, A.A.; Kroonenberg, S.B., and Naderi Bonab, M. 2014. Short- and long-term development of the Miankaleh Spit, southeast Caspian Sea, Iran. The development of the 60-km-long Miankaleh Spit in the southeastern corner of the Caspian Sea has been studied in two different timescales. At the start of the twentieth century 3 m sea-level cycle, the spit already existed, but it emerged prominently during the lowstand in the late 1970s, and drowned and fell apart into several islands during the following highstand that culminated in 1995. The analysis of core data and sedimentological analyses (grain size, biofacies, carbonate content, heavy mineral, and magnetic susceptibility) show that the Miankaleh Spit and the Gorgan Bay did not yet exist during the well-known 2600-2300 cal. YBP highstand, and at that time waves and longshore currents deposited barrier systems along the mainland coast. During the lowstand, deltas from rivers draining the eastern Alborz Mountains extended much more westward than at present. It was only during the last major highstand in the Little Ice Age that the present-day Miankaleh Spit was formed by eastward progradation caused by strong longshore currents. [ABSTRACT FROM AUTHOR]

Silva, R.; Martínez, M.L.; Hesp, P.; Catalan, P.; Osorio, A. F.; Martell, R.; Fossati, M.; Miot da Silva, G.; Mariño-Tapia, I.; Pereira, P.; Cienfuegos, R.; Klein, A., and Govaere, G., 2014. Present and future challenges of coastal erosion in Latin America. The coastal zones of Latin America have many landforms and environments, including sedimentary cliffs, deeply incised estuaries, headlands, barrier coasts and low lying, muddy coastal plains. These forms will respond differently to the expected changes in climate and associated sea level rise, which may produce coastal erosion in the future. Considering the coasts of Latin America overall, erosion is not yet a serious threat, although it is widespread and it is severe in some parts. Major erosion problems are frequently associated with human intervention in sediment supply, with poor planning or with the morphodynamic nature of the coast. Permanent erosional processes, locally or regionally, are caused by tectonic subsidence, deforestation and the fragmentation of coastal ecosystems, land use changes and sediment deficits because of infrastructure built along the coast. In this article we analyse coastal erosion in Latin America and the challenges it presents to the region. We first highlight the relevance of Latin America in terms of its biodiversity; then we describe the population at risk, demographic trends and economic growth throughout the low lying coastal zones. We also examine the vulnerability of the region by analyzing the resilience of key coastal ecosystems after exposure to the most frequent hazards that affect coastal zones in Latin America, namely tropical cyclones, sea level rise, ocean acidification, earthquakes and tsunamis. Finally, we discuss seven case studies of coastal erosion across Latin America. We close the study by pinpointing the main areas of concern in Latin America and explore possible strategies to overcome erosion and thus sustain economic growth, minimize population risk and maintain biodiversity. [ABSTRACT FROM AUTHOR]

Olea, R.A. and Coleman, J.L., Jr., 2014. A synoptic examination of causes of land loss in southern Louisiana as related to the exploitation of subsurface geologic resources. During the last 80 years, Louisiana has been losing wetlands at an average rate of 62 km2/y (24 mi2/y) for an accumulated loss of approximately 4900 km2 (1900 mi2). The loss seems to be the combined result of natural and anthropogenic causes that are behind primarily land subsidence averaging about 10 mm/y (0.4 in/y) coinciding with a sea level rise now at 3 mm/y (0.1 in/y), both contributing to coastal inundation. Upon completing extensive review of often controversial and conflicting views only synoptically reported here, conclusions reached by applying Monte Carlo simulation include: (1) geodetic measurements are consistent with independently postulated causes of regional subsidence; (2) ranking of subsidence factors shows that the main contributor to the regional subsidence is adjustment to sediment load in the form of lithosphere flexure followed by normal faulting dipping basinward, which combined, account on average for 70% of the subsidence, with compaction accounting for another 23%; and (3) production of oil and gas plays a tertiary role. The literature supports the historical view that before experiencing engineering modifications across the catchment area, sedimentation from the Mississippi River system was able to build a prograding coastline by overcoming subsidence rates of similar magnitude with more generous sediment loads of coarser particle size. Sea level rise will become an increasingly dominant factor in land loss only if the acceleration predicted by simulation model scenarios materializes. Wetland losses most likely will continue for as long as there is no compensation to counterbalance the negative effects of land subsidence and sea level rise, with the latter determining the pace of future losses. [ABSTRACT FROM AUTHOR]

Cline, M.D.; Feagin, R.A., and Yeager, K.M., 2014. Modeling salt marsh cover response to relative water level: Local fault motion versus global eustatic rise. The movement of growth faults on subsiding coastlines contributes to wetland losses, yet it has been unclear whether they can provide a point of reference for understanding the impacts of climate-induced relative sea level rise (RSLR) on wetland habitat. The objective of this study was to simulate land cover conversion as a function of RSLR within a wetland and to compare and contrast fault-induced elevation change with Intergovernmental Panel on Climate Change (IPCC) 2007 sea level rise projections. For an area surrounding a growth fault in Matagorda, Texas, aerial images were draped over a digital elevation model (DEM) to identify the dependent elevations of land cover classes and, subsequently, to model potential future outcomes based on variable RSLR rates. Modeling results show that rapid water-level rise can force wetland land-cover class conversion regardless of whether the rise is caused by vertical fault displacement or eustatic sea level rise. The model findings point to an RSLR rate of approximately 0.36 cm/y for complete loss of the Matagorda wetlands by 2100, although the sustainability of the wetlands in their current configuration and coverage will likely require rates well below the IPCC 2007 low rise rate. Current and historical record conditions of sea level rise, along the Texas Gulf Coast, greatly exceed the rates discussed, leaving a grim outlook for the coast in this region. [ABSTRACT FROM AUTHOR]

Kriebel, D.L. and Geiman, J.D., 2014. A coastal flood stage to define existing and future sea-level hazards. This paper explores the possible definition of a generic coastal flood stage (FS), an elevation at which significant flooding of local infrastructure is initiated, for regional or nationwide use in flood hazard analysis. By using monthly National Oceanic and Atmospheric Administration tidal gauge data from several coastal locations, a coastal FS based on the statistics of extreme high water events is proposed. This statistical FS is then compared to moderate and major FSs established by the National Weather Service with good agreement. Once adopted, the FS serves as a less ambiguous reference elevation or threshold to which the flooding potential of future storm events and sea-level rise can be compared and allows for consistent comparison between different sites. [ABSTRACT FROM AUTHOR]