Luz Clara, M.; Simionato, C.G.; D'Onofrio, E., and Moreira, D., 2015. Future sea level rise and changes on tides in the Patagonian Continental Shelf.

We investigate the effect of the future sea level rise (SLR) on the propagation of tides in the Patagonian Shelf by means of numerical simulations. Using a barotropic implementation of the Model for Applications at Regional Scales (MARS), we obtain solutions for scenarios which represent the present condition and potential future SLRs of 1, 2, and 10 m. The effect of flooding of low-lying areas is studied, and its influence on the propagation of tides in the region is discussed. Due to the coastal morphological features and the sense of tidal wave propagation in the Southern Hemisphere, inundation does not significantly modify the solution in the Patagonian Shelf; nevertheless, results are substantially changed in the much lower Northern Argentinean Shelf, north of 40° S, where dissipation is increased. The amplitude of M₂ responds to SLR in a spatially nonuniform manner. The response is nonlinear, particularly in regions close to the amphidromic points. Tidal dissipation by bottom friction increases consistently by 16% for the more extreme scenario with a generalized increment of tidal amplitudes, and therefore currents, over the Patagonian Shelf. Changes in the extension and position of tidal fronts are also explored. The results suggest that changes will be significant, with a reduction of the mixed areas in Cabo Blanco and San Sebastián and an increment of them in the vicinity of Península Valdés. Physical mechanisms that explain the observed modifications in the tidal regime are the changes with SLR of the speed of the tidal wave, the Rossby radius of deformation, the energy dissipation by bottom friction, and the resonant properties of the basin. Similarly to numerical studies performed for other coastal areas of the world, results indicate that important changes in the characteristics of tides can occur if SLR is large.

Carobene, L., 2015. Marine notches and sea-cave bioerosional grooves in microtidal areas: Examples from the Tyrrhenian and Ligurian coasts—Italy.

Modern and ancient marine notches are present along the cliffs and inside the sea caves of the Gulf of Orosei in Sardinia, the Gulf of Gaeta in Lazio, and in Western Liguria. A morphological quantitative study was undertaken to define the shape and size of notches and their altimetric correlation with the sea-level highstands that created them. The geometrical aspects of the notches along cliffs and the relationship between the mean sea level and the shape of the notch have allowed us to deduce that the main erosion process giving rise to the marine notches is wave action. Conversely, the bioerosive process is the most important cause leading to notch formation inside sea caves. These two types of notch differ in terms of their shape and size and while the former mainly develops above mean sea level, the latter extends below the mean high tide level. For the latter, we have proposed the term “sea-cave bioerosional groove.” The identification of the ancient grooves in the caves studied has provided a contribution to the understanding of the interglacial eustatic peak MIS 5.5. In the submarine part of limestone cliffs, the process of bioerosion attributable to marine borers has also been documented. This brings about the formation of underwater notches similar to the bioerosional grooves encountered in the caves. Analyses of the shape of marine notches have led to the identification of three stages of development, which in this paper are called “embryonic notch,” “complete notch,” and “mature notch.”

Ortiz Royero, J.C.; Plazas Moreno, J.M., and Lizano, O., 2015. Evaluation of extreme waves associated with cyclonic activity on San Andrés Island in the Caribbean Sea since 1900.

San Andrés Island is one of the most important tourist destinations in the Caribbean Sea. The extreme waves associated with storms and hurricanes since 1900 were studied. A total of 17 important events was identified in the last 100 years. During seven of these events, the eye of the storm was located less than 150 km from the coast: hurricanes Hattie (1961), Alma (1970), Irene (1971), Joan (1988), Cesar (1996), Katrina (1999), and, the most recent, Beta (2005). Most commonly, the storms approached from the SE; these storms affected the northern and southern portions of the island. Using the parametric hurricane wind model and simulating waves nearshore wave model, the wind and wave fields were modeled for the aforementioned hurricanes. The results showed that the western area of the island was unaffected by extreme waves, except for the waves caused by Beta in 2005, which were less than 2 m in height (on the 50-m isobath). However, the situation is different in the east. The wide insular shelf and coral reefs located along the northeastern coast act as a natural barrier dissipating the extreme waves so that most of the wave energy is dispersed before reaching the coastline. The southeastern coast is totally exposed to wave energy because of its narrow insular shelf and the limited presence of coral reefs. The maximum estimated significant heights were as much as 5 m on the 50-m isobath and occurred during Hurricane Joan (1988); the peak wave period was 12 seconds, and most of the hurricanes came from the SE. The present paper establishes a fundamental basis for implementing management plans during emergencies related to hurricanes, considering that the island has been affected by at least one hurricane every 10 years for the last 50 years.

Carle, M.V.; Sasser, C.E., and Roberts, H.H., 2015. Accretion and vegetation community change in the Wax Lake Delta following the historic 2011 Mississippi River flood.

During the 2011 Mississippi River flood, discharge to the lower river exceeded that of the 1927 and 1937 floods and the lower river remained above flood stage for nearly 2 months. A combination of WorldView-2 and Land Satellite 5 Thematic Mapper (Landsat 5 TM) imagery was used to assess the impact of this flood event on the Wax Lake Delta, one of few areas where the river is building new land. Vegetation community change was mapped from 2010 to 2011 and related to elevation change using plant species elevation distributions calculated from light detection and ranging (LIDAR) data. Changes in the land area in the delta were also assessed by regressing land area against water level for a series of pre- and postflood Landsat 5 TM images. The results indicate a net growth of 6.5 km² at mean water level and 4.90 km² at mean sea level. Areal gains were greatest at high water levels, indicating substantial vertical accretion across the subaerial delta. At least 8.7 km², or 31.8%, of the area studied converted to a higher-elevation species. The most change occurred at low elevations with conversion from fully submerged aquatic vegetation to Potamogeton nodosus and Nelumbo lutea. Conversion to lower-elevation species occurred across 3.4 km², or 12.8% of the study area, while 55.5% remained unchanged. The results highlight the importance of infrequent, large flood events in the maintenance of river deltas and provide a reference for estimating the impact of proposed large-scale river diversions on the Mississippi River Delta.

Landi, M. and Angiolini, C., 2015. Soil-plant relationships in Mediterranean salt marshes across dune-cultivated land gradient

The relationships between soil factors and plant species were investigated in salt marshes on the west coast of central Italy along a dune-cultivated land gradient with similar topographic elevations. Plant community composition was quantified in three zones (marsh-dune border, central marsh, and marsh-cultivated land border) identified across the gradient. The results suggest that the distribution and variation in abundance “performance” of plant species is mainly ruled by salinity and soil texture gradients (from sandy to silt-clay). Texture seemed to affect vegetation zonation in the marshes near sand dunes, since at the marsh-dune border the percentage of wind-blown sand increases. Variations in field capacity, total organic carbon, pH, and calcium carbonate did not appear to control the performance of plant species. Indications on the performance of six species are provided. Limbarda crithmoides increased with the amount of sand and was often located at the marsh-dune border. Elymus repens and Phragmites australis increased with decreasing salinity and were frequently found at marsh borders, however E. repens also increased with the amount of silt-clay. Sarcocornia fruticosa increased with salinity and silt-clay, while Halimione portulacoides increased with salinity and seemed less subject to changes in soil texture. Elymus pycnanthus increased with salinity and decreased with the amount of silt-clay, however, the ordination suggested that other factors may be determinant for this species. These species could be useful to map saline environments and to reconstruct an appropriate scenario in restoration projects of Mediterranean salt marshes.

Pu, R.; Bell, S., and English, D., 2015. Developing hyperspectral vegetation indices for identifying seagrass species and cover classes.

Seagrass habitats are characteristic features of shallow waters worldwide and provide a variety of ecosystem functions. To date, few studies have evaluated the efficiency of spectral vegetation indices (VIs) for characterizing aquatic plants. Here we evaluate the use of in situ hyperspectral data and hyperspectral VIs for distinguishing among seagrass species and levels of percentage submerged aquatic vegetation (%SAV) cover in a subtropical shallow water setting. Analysis procedures include (1) retrieving bottom reflectance, (2) calculating correlation matrices of VIs with %SAV cover and F value matrices from analysis of variance among species, (3) testing the difference of VIs between levels of %SAV cover and between species, and (4) discriminating levels of %SAV cover and species by using linear discriminant analysis (LDA) and classification and regression trees (CART) classifiers with selected VIs as input. The experimental results indicated that (1) the best VIs for discriminating the four levels of %SAV cover were simple ratio (SR) VI, normalized difference VI (NDVI), modified simple ratio VI, and NDVI × SR, whereas the best VIs for distinguishing the three seagrass species included the weighted difference VI, soil-adjusted VI (SAVI), SAVI × SR and transformed SAVI; (2) the optimal central wavelengths for constructing the best VIs were 460, 500, 610, 640, 660, and 690 nm with spectral regions ranging from 3 to 20 nm at band width 3 nm, most of which were associated with absorption bands by photosynthetic and other accessory pigments in the visible spectral range. Compared with LDA, CART performed better in discriminating the four levels of %SAV cover and identifying the three seagrass species.

Mashhadi, L.; Zaker, N.H.; Soltanpour, M., and Moghimi, S., 2015. Study of the Gonu tropical cyclone in the Arabian Sea.

The waves created in the Arabian Sea by the Gonu tropical cyclone have been simulated in this paper by employing the Simulating Waves Nearshore (SWAN) third-generation spectral wave model. The model was established in a nonstationary mode. The linear and exponential growth from the wind input, the wave–wave nonlinear interaction, the whitecapping, and the bottom friction were considered in the simulation. The model results are compared with data measured at three stations on the Chahbahar Bay, which is located in the south of Iran. The significant wave height, the peak wave period, and the mean wave direction are the three key peak features taken into account. The results show that the significant wave height and the mean wave direction can be reasonably predicted. However, the simulated peak wave period is underestimated. The distribution of the wave fields is obtained to assess the critical wave in the given area. The results show that the SWAN procedure can produce accurate-enough results when simulating open ocean.

Leung, J.Y.S., 2015. Habitat heterogeneity determining the macrobenthic infaunal community in a mangrove swamp in South China: Implication for plantation and plant invasion.

Mangroves have been severely disturbed by human exploitation over the last few decades, and mangrove plantation programs have been launched to restore degraded mangroves worldwide. However, mangrove plantations can change habitat heterogeneity, potentially altering the macrobenthic infaunal community, an important constituent in mangrove ecosystems. The Tai O mangrove swamp in Hong Kong was chosen as the study site for evaluation of the significance of habitat heterogeneity on the macrobenthic infaunal community by interpreting infaunal and environmental data through univariate and multivariate analyses. Infauna and sediment samples were collected by sediment cores in habitats with an increasing order of habitat heterogeneity (mudflat < seedling < Kandelia < Kandelia with algal mats < pneumatophore). Compared with other areas, a higher Shannon-Weaver index was found in the seedling area and higher abundance was found in the mudflat area. Spearman correlation analysis revealed that abundance, Margalef's species richness, and the Shannon-Weaver index were negatively correlated with root biomass, particle size in phi value, and redox potential. Analysis of similarities revealed that different habitats had different macrobenthic infaunal communities. Biota–environment analysis and a distance-based linear model both showed unequivocally that root biomass was the paramount factor in determining the macrobenthic infaunal community. The findings signified the importance of habitat heterogeneity, largely depending on root biomass, in determining the macrobenthic infaunal community and implied that plantation or plant invasion in open areas poses far-reaching consequences in mangrove ecosystems.

Weymer, B.A.; Houser, C., and Giardino, J.R., 2015. Poststorm evolution of beach-dune morphology: Padre Island National Seashore, Texas.

The response and recovery of barrier islands to extreme storms and ultimately to relative sea-level rise depends on the height and extent of the foredunes relative to storm surge. The impact of storms is complicated by the tendency of dune morphology to vary alongshore at a range of spatial scales, and it is reasonable to assume that this variable response will be preserved within subsurface stratigraphy. We used ground-penetrating radar (GPR) and vibracores to investigate subsurface structures for foredunes of different heights within a 2.5-km section of beach at Padre Island National Seashore, Texas. Identical, laterally continuous radar reflectors were observed at each site at a depth of ~1.2 m and interpreted as a storm surface. Results from the smallest dune suggest that the dune experienced little net erosion during the storm but also exhibited the least recovery. The intermediate dune was completely eroded by the storm but also exhibited the greatest recovery through the migration of accretionary mounds driven by aeolian transport, leading to the development of embryo dunes forming the modern dune core. The largest dune was scoured at the base and experienced little poststorm recovery, except for beachface recovery. Thus, the response and recovery of adjacent, but morphologically distinct, dunes is quite different over the same sequence of storm activity. We suggest that the extent and form of beach-dune recovery is dependent on the impact scale of the storm and may represent a reinforced process once alongshore variations in dune height are initialized.

Andrade, L.S.; Fransozo, V.; Bertini, G.; Negreiros-Fransozo, M.L., and López-Greco, L.S., 2015. Reproductive plasticity in the speckled crab Arenaeus cribarius (Decapoda, Brachyura, Portunidae) associated with a population decline.

Reproductive strategies are responsible for population maintenance, and when equilibrium is achieved, the selected strategy may become a pattern. The shaping of these patterns is an important resource for a species' conservation and should receive special attention. The population biology of Arenaeus cribrarius was evaluated, focusing on recruitment, sexual maturity, and reproductive period, and the results were compared with available information about this species from previous catches. Crabs were collected monthly for 3 years, and for each specimen the sex, gonadal development, breeding condition, and carapace width (CW) were recorded. Seawater temperatures (from bottom and surface) were also recorded. Reproduction and recruitment only occurred during the warmer months of the year, and size at sexual maturity was smaller (50.1 mm CW) in males than in females (56.3 mm CW). These features differed from previous studies of the same species in the same sampling area, suggesting the plasticity of the reproductive strategy to optimize reproductive success and survival of the larvae.

Diversas estratégias reprodutivas podem ser utilizadas para manutenção de uma população e, quando o equilíbrio é atingido, a estratégia escolhida passa a ser padrão. A modelagem desses padrões representa um importante recurso para a conservação da espécie e deve receber atenção especial. A biologia populacional de Arenaeus cribrarius foi avaliada com ênfase aos aspectos: recrutamento juvenil, maturidade sexual e período reprodutivo; os resultados discutidos e comparados com informações disponíveis sobre a espécie na literatura. Os siris foram coletados, mensalmente, por um período de três anos. Informações biológicas foram registradas para cada espécime: sexo, desenvolvimento gonadal, condição de ovígera e largura da carapaça. Em relação aos parâmetros ambientais, analisou-se a temperatura da água do mar (de fundo e superfície). Constatou-se períodos de reprodução e recrutamento sazonais, ocorrendo nos meses mais quentes do ano. Ao estimar a maturidade sexual, foi observado que o tamanho atingido pelos machos nessa fase (50,1 mm), é menor que aquele atingido pelas fêmeas (56,3 mm). As diferenças verificadas nas características reprodutivas de A. cribrarius, quando confrontadas com estudos anteriores, permitem sugerir que a espécie tenha modelado sua estratégia reprodutiva a fim de garantir o máximo sucesso reprodutivo e sobrevivência das larvas.

Calegario, G.; Salomão, M.S.M.B.; de Rezende, C.E., and Bernini, E., 2015. Mangrove forest structure in the São João River estuary, Rio de Janeiro, Brazil.

Natural and anthropic factors contribute toward the formation of environmental gradients that act as selective forces that in turn determine the distribution of the mangrove species along these gradients. The aim of this study is to characterize the structure of two mangrove forests under different conditions of salinity and compare the structural parameters between the border and inside forests in the São João River estuary. One site 11 km from the ocean (upper estuary, site 1) and another 3 km from the ocean (lower estuary, site 2) were selected along the estuary. Within each site measurements of height and diameter breast height (DBH ) of individuals ≥1 m in height, and the pore-water salinity, granulometry, and organic matter of the sediment were analyzed. The average tree height varied from 3.1 to 6.1 m, the average DBH from 3.7 to 7.0 cm, the density from 5240 to 14,720 trunks ha⁻¹, and the basal area from 8.0 to 35.5 m² ha⁻¹. A pattern of zonation was observed along the estuary, with Laguncularia racemosa (L.) Gaertn. f. dominant in the upper estuary and Rhizophora mangle L. dominant in the lower estuary. We observed no zonation of species between border and inside forest, but L. racemosa exhibited higher density in the upper estuary, and R. mangle in the lower estuary, thus defining a pattern of spatial zonation along the estuary.

Qiu, C. and Zhu, J., 2015. Assessing the influence of sea level rise on salt transport processes and estuarine circulation in the Changjiang River estuary.

Global sea level rise has been greatly concerned by government and society with its effects on saltwater intrusion and material transport in estuaries, which threaten freshwater habitat and drinking water supplies. A semi-implicit estuarine, coastal, and ocean model (ECOM-si) was used to assess the influences of rising sea level on salt transport processes and estuarine circulation patterns in the Changjiang River estuary, China. The variations of intruding saltwater and residual salt transport were simulated according to the variations of several sea level rise scenarios, and results in typical year and dry year were demonstrated, respectively. The modeled results are in good agreement with the observed data, and statistics show good correlation coefficient and Skill Score values. Results from the numerical experiments show that the intensity of saltwater intrusion and stratifications both increase as sea level rises, while the increments are quite distinct between each channel. Furthermore, it shows obvious interannual changes following different river discharges. The residual transport of salt was used to analyze the changes in transport processes and estuarine circulation pattern. The computation results show that the Stokes drift transport is the major mechanism for up-estuary salt transport in each channel, whereas the seaward Eulerian transport is of the same order. The flux of saltwater spillover from the North Branch into the South Branch increases with stronger Stokes transport as sea level rises. The landward salt transport is strengthened in the North Channel and may further affect the upper reaches under strengthened tidal pumping and vertical shear transport with higher sea level. The overtopping flow affected by tidal pumping is the dominant mechanism for salt exchange between the North Passage and South Passage. This may increase the salt supply from the ocean into the South Channel.

Li, L.; Wu, H.; Liu, J. T., and Zhu, J., 2015. Sediment transport induced by the advection of a moving salt wedge in the Changjiang Estuary.

This study focused on the intratidal variations of suspended sediment concentration (SSC) and residual sediment transport near a moving salt wedge in the Changjiang Estuary. The stratification was controlled by the advection of the salt wedge and was strengthened during the flood tide and weakened during the ebb tide. This phenomenon is the opposite of systems that are dominated by tidal straining of salinity, which diminishes the stratification during the flood tide and enhances it during the ebb tide. The enhanced stratification during the flood tide restricts turbulent mixing; hence, the resuspended sediment is concentrated below the pycnocline. Because of the stronger turbulent mixing during the ebb tide, the suspended sediment can be elevated to the surface, decreasing the near-bottom SSC. Such tidal asymmetries of mixing and near-bottom SSC cause the net sediment flux to be directed landward in the lower layers after a tidal cycle.

Azhikodan, G. and Yokoyama, K., 2015. Temporal and spatial variation of mixing and movement of suspended sediment in the macrotidal Chikugo River estuary.

The effect of mixing on the movement of the estuarine turbidity maximum (ETM) was examined in the highly turbid Chikugo River estuary, Japan, in consideration of four significant issues: semidiurnal and semilunar tidal variations, spatial distribution, and synchronism of data acquisition. Vertical profiles of salinity and turbidity were measured for 2 weeks at 1 km intervals from the river mouth (0 km) to 17 km upstream, with a short duration for every cruise. Spring-neap transition and the spatial variation of mixing, and suspended sediment concentration (SSC) was found during the semilunar tidal cycle. The estuary gradually changed from a vertically well-mixed condition during spring tide to a stratified condition during the neap tide via a partially mixed condition during the intermediate half tides. The relationship between the flow ratio and the SSC showed that ETM growth was dominated by both tidal forcing and freshwater flow. SSC was high when the salinity was 0.5 practical salinity units (psu) in the upper estuary and 10 psu in the lower estuary. For the same mixing strength (MS), SSC in the lower estuary was greater than that in the upper estuary. Based on flow ratio, salinity, and MS, the occurrence of the ETM and its development at the macrotidal estuary was a consequence of three processes: bed-sediment erosion by seawater in the lower estuary, sediment transport in the estuarine channel by the tidal current and freshwater flow, and sediment accumulation at the salinity front in the upper estuary.

Marchese, C.; Lazzara, L.; Pieri, M.; Massi, L.; Nuccio, C.; Santini, C., and Maselli, F., 2015. Analysis of chlorophyll-a and primary production dynamics in north Tyrrhenian and Ligurian coastal–neritic and ocean waters.

Properly tuned algorithms based on optical remote sensing data can provide estimates of chlorophyll-a (as a proxy for phytoplankton biomass) concentration in near real time, allowing the monitoring of phytoplankton dynamics for both neritic and oceanic areas. The main objective of this study was, through the use of ocean color satellite images, to offer a description of the interannual variability of chlorophyll-a and primary production both in coastal–neritic and in oceanic areas of the North Tyrrhenian and Ligurian Seas (NW Mediterranean). The second objective was to highlight the possible influence of land runoff on phytoplankton biomass variability in coastal–neritic waters. The results indicate that seasonal cycles of phytoplankton biomass and production were quite different in neritic areas potentially affected by freshwater runoff compared to offshore waters. Neritic areas are characterized by an anticipated bloom (winter–spring) and by higher spatial variability that appears to be linked with the distance from shore. Meanwhile, oceanic areas are dominated by a marked seasonal cycle and the typical bloom occurs in spring (March–April) in relation with vertical mixing. Finally, linear regression analysis suggests the influence of freshwater runoff in modulating the variability of chlorophyll-a in coastal–neritic areas. Overall, the results confirm previous observations on the dynamics of phytoplankton biomass and contribute to more realistic and lower estimates of both chlorophyll-a concentration and annual primary production.

Yuan, S.; Li, L.; Amini, F., and Tang, H., 2015. Sensitivity of combined turbulent wave overtopping and storm surge overflow response to variations in levee geometry.

Overtopping of earthen levees produces fast-flowing, turbulent water velocities on the land-side slope that can damage the protective grass covering and expose the underlying soil to erosion. High-performance turf reinforcement mat (HPTRM) is one of the most advanced flexible armoring technologies for severe erosion challenges. Response to combined wave overtopping and storm surge overflow of an HPTRM-strengthened levee was studied in a three-dimension full-scale numerical flume. Little information is known about the role of levee geometry in the performance of an HPTRM-strengthened levee during turbulent overtopping conditions. The goal of this study was to investigate the sensitivity of combined wave overtopping and storm surge overflow response to variations in levee geometry. This is important since the geometry directly impacts the levee performance and levee design. Four conceptual models of different-morphology levees with different significant wave heights were simulated. The models included a total of 25 different combined overtopping cases with various hydrodynamic conditions. The impacts of crest widths, land-side and sea-side slopes, and an additional mild berm on the overtopping discharge, turbulent bottom shear stress, turbulent kinetic energy, and erosion rate at the toe of land-side slope were investigated. New empirical equations based on these structural parameters were developed.

Mahgoub, M.; Hinkelmann, R., and La Rocca, M., 2015. Understanding the behaviour of gravity currents in tideless estuaries and considering the impact of sea level rise within the Nile Estuary.

Gravity currents are complex phenomena that occur in estuaries, and the complexity of these phenomena is even higher for tideless estuaries. To improve the process of understanding such phenomena, the three-dimensional TELEMAC3D modelling system was used to model the Nile estuary as an example of tideless estuaries. The nonhydrostatic simulation and the use of a complex turbulence model were necessary. The current mean flow conditions were modelled first; the results were then compared with three scenarios of sea level rise to study its impact. According to the model results, the salt wedge was not stagnant but fluctuated in cycle-like variations; the fluctuations were higher at the surface and smaller near the bottom, and at the end of the salt wedge, no fluctuations were noticed. The salt concentration and hence the density differs significantly throughout the salt wedge in the longitudinal direction as well as in the vertical direction. Changes in density in the lateral direction were also noticed; greater concentrations were at greater water depths for the same transverse section. The sea level rise caused greater saltwater intrusion inside the Nile and the greater the sea level rise, the more the intrusion increased. To maintain the current saltwater intrusion length without any increase, discharging additional water from the Edfina Barrage (the last barrage on Rosetta branch) could be used as a direct mitigation option; however, doing so, could have negative consequences on the water budget of the country.

Cheng, T.K.; Hill, D.F., and Read, W., 2015. The contributions to storm tides in Pacific Northwest estuaries: Tillamook Bay, Oregon, and the December 2007 storm.

The December 2007 storm, otherwise known as the Great Coastal Gale of 2007, was a series of extratropical cyclones that brought highly unprecedented wind speeds and precipitation to the Oregon and Washington coasts of the United States. A storm hindcast using the coupled Advanced Circulation (ADCIRC) and Simulating Waves Nearshore (SWAN) models was conducted within Tillamook Bay, Oregon, from 28 November to 5 December 2007. ADCIRC computes two-dimensional circulation forced by astronomic tides, streamflow, and storm surge, while SWAN solves the wave action density equations for radiation stresses. Modeled nontidal residuals were compared to observed data collected by the National Oceanic and Atmospheric Administration at the Garibaldi, Oregon, tide gauge station. The relative contributions of meteorological forcing, offshore waves, and streamflow to storm tides were next assessed at four locations of interest within and outside the estuary by conducting a set of model runs where each major process was omitted in turn. The dominant mechanism for storm tides in the estuary was offshore wave breaking. Streamflow, locally (in estuary) generated waves, and locally generated surge led to minor variations in storm tides in the estuary.

Xu, Y.; Zhang, W.; Chen, X.; Zheng, J.; Chen, X., and Wu, H., 2015. Comparison of analytical solutions for salt intrusion applied to the Modaomen Estuary.

Salt intrusion in estuaries is an urgent environmental challenge across the world, because salinity influences water quality. The Modaomen Estuary is the main source of freshwater supply in the economically advanced Pearl River Delta, and it is experiencing a salt intrusion problem. Analytical models of salinity variation offer a simple and efficient approach to studying salt intrusion in estuaries. In this paper, two analytical models used worldwide to assess salinity variation in alluvial estuaries are applied to the Modaomen Estuary. The models are derived from salt convection-dispersion equations, with different assumptions for the dispersion coefficient. The performance of these two models was evaluated by comparing their results with field measurements; this revealed that both analytical models apply well to both the estimation of salinity distribution and the prediction of salt intrusion in the Modaomen Estuary. One model agrees more with the field measurements of salinity distribution along the estuary; the second better predicts salt intrusion length.

Savoya, V.; Gómez Otero, J., and Schwindt, E., 2015. Toward a better understanding of the native–nonnative status of Mytilus mussels in the southwestern Atlantic: comparing pre-European middens and modern populations.

The aim of this study is to determine the degree of similarity of the Mytilus mussels currently found along the Patagonian coast of Argentina to those found in pre-European colonization middens, in order to approach an understanding of whether the former are native or not. An elliptic Fourier analysis between pre-European archaeological (native) and modern mussels (cryptogenic) was performed, and the resulting data were analyzed with multivariate approaches (principal component analysis, discriminant function analysis, and cluster analysis). Our results showed that when all samples belonging to the Patagonian coast were included on a single analysis, modern and archaeological mussels were clustered in two major groups, matching the macroregional marine biogeographic scheme. In addition, morphometric differences were detected when modern and archaeological mussels from similar latitudes were compared. We discuss these results in light of the natural and anthropogenic changes that occurred along the Argentinean coast together with the environmental changes occurring between the biogeographic provinces along the SW Atlantic coast.

El objetivo del presente trabajo es realizar un estudio morfológico entre valvas de mejillones Mytilus actuales y arqueológicos de la costa patagónica de Argentina, a fin de brindar una nueva perspectiva que permita mejorar el conocimiento sobre el origen nativo o invasor de los mejillones Mytilus actuales. Valvas arqueológicas (nativas) y actuales (criptogénicas) se estudiaron mediante el análisis elíptico de Fourier, y los datos obtenidos se analizaron con análisis multivariados (análisis de componentes principales, análisis de función discriminante, análisis de conglomerados y MANOVAs). Por un lado, los resultados muestran que en un análisis conjunto de todas las muestras (i.e. actuales y arqueológicas) éstas se agruparon siguiendo el esquema biogeográfico del mar argentino. Por otro lado, las valvas actuales y arqueológicas procedentes de latitudes similares de la costa patagónica se diferenciaron morfométricamente. Los resultados se discuten a la luz de los cambios naturales y antropogénicos ocurridos a lo largo de la costa argentina, y considerando además las diferencias ambientales entre ambas provincias biogeográficas del mar argentino.

Lonard, R.I.; Judd, F.W., and Stalter, R., 2015. Biological flora of coastal dunes and wetlands: Borrichia frutescens (L.) DC.

Borrichia frutescens (L.) DC. is a New World warm-temperate, subtropical, and tropical zone, perennial subshrub that is an important species in hypersaline coastal sites. Also known as sea ox-eye, it tolerates salinities ranging from less than 20 ppt to 130 ppt. It occurs in substrates low in organic matter and deficient in nitrogen, phosphorus, and potassium. Nearly all reproduction is vegetative from an extensive rhizome system. Populations of this species recover quickly after coverage by wrack. Stands of B. frutescens often dominate the landward border of salt marshes.

Watson, P.J., 2015. Development of a unique synthetic data set to improve sea-level research and understanding.

One of the most fundamental, critical environmental issues confronting mankind into the foreseeable future remains the ominous spectre of climate change, in particular the pace at which impacts will occur and our capacity to adapt. Sea-level rise is one of the key artefacts of climate change that will have profound effects on global coastal populations. Although extensive research has been undertaken into this issue, there remains considerable conjecture and scientific debate about the temporal changes in mean sea level and the climatic and associated physical forcings responsible for them. In particular, over recent years, significant debate has centred around the issue of a measurable acceleration in ocean water-level records, a feature central to projections based on the current knowledge of climate science. The complexity of the dynamic influences and noise embedded within ocean water-level data sets has led sea-level research toward successively more sophisticated time series analytical techniques to estimate the trend. In the absence of an absolute knowledge of the mean sea-level signal (or trend) for a particular record, the accuracy of the trend has increasingly been inferred from the assumed sophistication of the underpinning analytical approach applied to the data record. An innovative and transparent process by which to identify the most efficient analytical technique for isolating the mean sea-level signal is to test such approaches against “synthetic” (or custom built) data sets with a known mean sea-level signal. This paper details the development of a monthly average data set to meet the aforementioned objective.