McLaren, P., 2016. The environmental implications of sediment transport in the waters of Prince Rupert, British Columbia, Canada: A comparison between kinematic and dynamic approaches.

A Sediment Trend Analysis (STA®) was performed on 2474 grain-size distributions taken from the Port of Prince Rupert, British Columbia, Canada. The analysis was commissioned by the Lax Kw'alaams First Nations Band because of environmental concerns associated with future large-scale development plans, including a proposed liquefied natural gas (LNG) terminal associated with Flora Bank. Located at the mouth of the Skeena River, Flora Bank has long been considered an important nursery area for juvenile salmon. STA is an empirical technique to determine patterns of net sediment transport, which may provide a qualitative assessment of the possible environmental changes that could be expected following port construction. The patterns of transport revealed that sediments throughout the study area are derived from underlying till which is exposed in areas of strong currents. Flora Bank, a roughly 4 km² area of intertidal sand, contained the coarsest and most well sorted sand, which was not found elsewhere throughout the study area. Although derived from till, the sand did not form transport pathways from the other sediment types; in addition, pathways could not be determined on the bank itself. It is concluded that the surficial sediments of Flora Bank are a lag derived from underlying glacial deposits caused as coastal processes became active during a lowering sea level that reached its present position about 8000 years ago. They are, therefore, relict sediments held in place by the processes surrounding the bank. This suggests that the design plan for the proposed LNG terminal could disrupt the processes in such a way that sand could be lost from the bank. This finding is contrary to that derived from numerical modeling, which concludes that no environmental harm will be done. Efforts are presently underway for future collaboration in an attempt to resolve the discrepancy and to more accurately understand the risks to Flora Bank.

Funderburk, W.R.; Carter, G.A., and Anderson C.P., 2016. Evaluating the Influence of elevation and impact of hurricane Katrina on radial growth in slash pine (Pinus elliottii var. elliottii Engelm) on Cat Island, Mississippi, U.S.A.

Hurricane Katrina heavily affected the Mississippi barrier islands, in the northern Gulf of Mexico, on 29 August 2005. On Cat Island, Mississippi, field observations of geographic patterns in poststorm survival of slash pine (Pinus elliottii var. elliottii Engelm) suggested that its growth and resiliency to storm impact may depend substantially on ground elevation. This hypothesis was tested by evaluating the lifetime mean radial growth rate (in millimeters per year), stem (trunk) diameter (in centimeters), the percentage of change in the radial growth rate for the initial 5-y period after the storm (2006–10) vs. the 5-y period before the storm (2001–05), and the yearly percentage increase in stem radius and basal area for 2001–10 with respect to high-accuracy GPS measurements of growth-site elevation. Radial growth declined after the storm and remained suppressed in 2006–10. However, simple regressions indicated no relationship between growth and elevation, either over the lifetime of the trees or on a yearly basis in 2001–10. Instead, radial growth was related to tree age and, most strongly, to reciprocal age. Notably, the relationship with age diminished while growth was suppressed in 2005–10. Although tree growth was not related to elevation, a future study will explore the mechanisms underlying an observed 0.5-m elevation threshold for slash pine existence on Cat Island.

Otsuka, A.Y.; Feitosa, F.A.N.; Flores-Montes, M.J., and Silva, A., 2016. Dynamics of chlorophyll a and oceanographic parameters in the coastal zone: Barra das Jangadas-Pernambuco, Brazil.

The Pernambuco shelf, inserted into the NE-E continental margin of Brazil, is about 187 km long and is characterized by reduced width, shallow depth, gentle slope, relatively warm water, and high salinity. It is influenced to some extent by translittoral rivers, the Jaboatão River being among these. This study aimed to analyze the dynamics of chlorophyll a and hydrological parameters on the Pernambuco inner continental shelf under the influence of the Jaboatão River plume. Bimonthly samplings were carried out during the rainy and dry seasons at one point in the estuarine area and four points along the adjacent inner continental shelf. The parameters evaluated were chlorophyll a, temperature, salinity, transparency, dissolved oxygen, suspended particulate matter, pH, depth, and inorganic nutrients. Most parameters had significant seasonal variation. In the dry period, chlorophyll-a ranged from 2.89 to 34.71 mg m⁻³ in the estuary and varied from 0.21 to 9.67 mg m⁻³ on the shelf. In the rainy period, it varied from 0.79 to 12.46 mg m⁻³ in the estuary and from 0.26 to 4.59 mg m⁻³ on the shelf. According to a principal components analysis, chlorophyll a showed a direct relationship with oxygen saturation rate and temperature and an inverse relationship with pH, salinity, and water transparency. Two points on the shelf (points 3 and 4) were most influenced by river outflow. The limiting factor for phytoplankton biomass was water turbidity due to the higher values reached in the dry period. The estuarine zone was in a stage of high eutrophication, thus sometimes affecting the waters of the inner shelf.

A plataforma de Pernambuco está inserida na margem continental nordeste-leste do Brasil, possui cerca de 187 Km de extensão e se caracteriza por ter uma reduzida largura, pouca profundidade, declive suave, águas relativamente quentes, elevada salinidade. Recebe influência de alguns rios translitorâneos, dentre eles, o rio Jaboatão. O presente trabalho apresentou como objetivo analisar a dinâmica da clorofila a e parâmetros hidrológicos na plataforma continental de Pernambuco sob o efeito da pluma do rio Jaboatão. Foram realizadas coletas bimestrais, no período chuvoso e estiagem, em um ponto na zona estuarina e quatro ao longo plataforma continental adjacente. Os parâmetros avaliados foram: clorofila a, salinidade, oxigênio dissolvido, material particulado em suspensão e nutrientes inorgânicos dissolvidos. A maioria dos parâmetros apresentou variação sazonal significativa. A clorofila a no estuário variou de 2,89 à 34,71 mg.m⁻³ e na plataforma continental de 0,21 à 9,67 mg.m⁻³ no período de estiagem e, no período chuvoso, apresentou uma variação no estuário de 0,79 à 12,46 mg.m⁻³ e na plataforma de 0,26 à 4,59 mg.m⁻³. De acordo com ACP, a clorofila a apresentou uma relação direta com a temperatura e taxa de saturação do oxigênio e inversa com pH, salinidade e transparência da água. Os pontos da plataforma que mais sofreram influência do deságüe fluvial foram os pontos centrais P3 e P4. O fator limitante para a biomassa fitoplanctônica foi a turbidez da água e os maiores teores foram observados no período de estiagem. A zona estuarina encontra-se em um elevado processo de eutrofização antrópica e, desta forma, vem interferindo na qualidade das águas da plataforma continental.

Mann, T.; Bayliss-Smith, T., and Westphal, H., 2016. A geomorphic interpretation of shoreline change rates on reef islands.

Recent-past shoreline changes on reef islands are now subject to intensified monitoring via remote sensing data. Based on these data, rates of shoreline change calculated from long-term measurements (decadal) are often markedly lower than recent short-term rates (over a number of years). This observation has raised speculations about the growing influence of sea-level rise on reef island stability. This observation, however, can also be explained if we consider two basic principles of geomorphology and sedimentology. For Takú Atoll, Papua New Guinea, we show that natural shoreline fluctuations of dynamic reef islands have a crucial influence on the calculation of short-term rates of change. We analyze an extensive dataset of multitemporal shoreline change rates from 1943 to 2012 and find that differing rates between long- and short-term measurements consistently reflect the length of the observation interval. This relationship appears independent from the study era and indicates that reef islands were equally dynamic during the early periods of analysis, i.e. before the recent acceleration of sea-level rise. Consequently, we suggest that high rates of shoreline change calculated from recent short-term observations may simply result from a change in temporal scale and a shift from geomorphic equilibrium achieved over cyclic time toward an apparent disequilibrium during shorter periods of graded time. This new interpretation of short- and long-term shoreline change rates has important implications for the ongoing discussion about reef island vulnerability, showing that an observed jump from low to high rates of change may be independent from external influences, including but not limited to sea-level rise.

An, S. and Takewaka, S., 2016. A study on the morphological characteristics around artificial headlands in Kashima Coast, Japan.

Field observations with X-band marine radars of spatiotemporal variations of morphology around three artificial headlands were done along a well-developed 16-km-long sandy beach in 2010. The radar images were time averaged and stacked to identify water- and breaker lines around the headlands. Various characteristics of the shoreline variations were analyzed by the empirical orthogonal function method. Seasonal characteristics were discussed with seasonal incident waves and were attributed to seasonal wave conditions. Spatial variations were categorized into an asynchronous or synchronous pattern and were associated with a surf zone extension. Locations of breaker lines relative to the tips of the headlands were categorized into four types and related to the shoreline variabilities, revealing that the surf zone extension was the dominant influence on the synchronization of the shoreline variability. Shoreline positions relative to the tips of the headlands were inferred as the main cause of the surf zone extension, and frequencies of surf zone extension were understood in terms of intertidal foreshore slopes around the headlands.

La Peyre, M.K.; Geaghan, J.; Decossas, G., and La Peyre, J.F., 2016. Analysis of environmental factors influencing salinity patterns, oyster growth, and mortality in lower Breton Sound Estuary, Louisiana, using 20 years of data.

Freshwater inflow characteristics define estuarine functioning by delivering nutrients, sediments, and freshwater, which affect biological resources and ultimately system production. Using 20 years of water quality, weather, and oyster growth and mortality data from Breton Sound Estuary (BSE), Louisiana, we examined the relationship of riverine, weather, and tidal influence on estuarine salinity, and the relationship of salinity to oyster growth and mortality. Mississippi River discharge was found to be the most important factor determining salinity patterns over oyster grounds within lower portions of BSE, with increased river flow associated with lowered salinities, while easterly winds associated with increased salinity were less influential. These patterns were consistent throughout the year. Salinity and temperature (season) were found to critically control oyster growth and mortality, suggesting that seasonal changes to river discharge affecting water quality over the oyster grounds have profound impacts on oyster populations. The management of oyster reefs in estuaries (such as BSE) requires an understanding of how estuarine hydrodynamics and salinity are influenced by forcing factors such as winds, river flow, and by the volume, timing, and location of controlled releases of riverine water.

Reisinezhad, A.; Mazaheri, S.; Hejazi, K., and Jabbari, M.H., 2016. A novel finite element scheme of Nwogu extended Boussinesq equations to predict free surface elevation over different bathymetry of beaches.

In this study, free surface elevation is predicted by using a new finite element scheme. This numerical method solves a Nwogu Boussinesq equation system to simulate wave propagation in the complicated bathymetry of coastal regions. The numerical approach is based on a Galerkin finite element approach for spatial discretization and Adam-Bashforth-Moulton predictor-corrector strategy for time integration. Governing equations are rewritten in lower-order forms by introducing a novel form of auxiliary variable in order to make the application of the linear finite element method possible. Then, the stability of the suggested finite element schemes is studied using a theoretical analysis. For the validation of the present numerical method, five test cases are considered to show the capability of the numerical model for simulating the free surface elevation of wave propagation over different beach profiles where the nonlinear and dispersive effects are so important. The simulated results agree well with experimental observations.

Bracs, M.A.; Turner, I.L.; Splinter, K.D.; Short, A.D.; Lane, C.; Davidson, M.A.; Goodwin, I.D.; Pritchard, T., and Cameron, D., 2016. Evaluation of opportunistic shoreline monitoring capability utilizing existing “surfcam” infrastructure.

This paper investigates the opportunistic repurposing of existing low-elevation recreational surf cameras (“surfcams”) to provide quantitative shoreline position data. Shoreline data are of fundamental importance in coastal management; however, intensive effort is required to routinely sample this dynamic environmental parameter. Established (and generally research-oriented) coastal imaging systems provide shoreline data in higher temporal resolution across broader spatial scales than is achievable by traditional survey techniques. The key benefits of adopting surfcams for shoreline monitoring are the wide availability of existing stations and their relatively low cost. In addition to the known challenges of optical remote sensing, there are further constraints associated with the typically low elevations of surfcams (9 to 22 m in this study) and the common use of dynamic pan-tilt-zoom positioning. This study used surfcams at nine diverse sites along the SE Australian coastline. Surfcam-derived shorelines were evaluated against monthly real time kinematic global navigation satellite system (RTK-GNSS) surveys. Standard deviations (SDs) of error of 4 to 14 m (horizontal) were observed in data provided by the commercial surfcam operator. After consideration of image geometry, camera stability, shoreline visibility, and shoreline elevation, SDs of error within 1 to 4 m were achieved. At one site, daily surfcam-derived shorelines were evaluated against video-derived shorelines obtained by a state-of-the-art Argus coastal imaging system. Data provided by the surfcam operator had a SD of error of 6 m (horizontal) when compared to the Argus-derived shoreline dataset, and improved methodology reduced this to below 2 m. Generic methods for identifying and addressing issues resulting from surfcam movement and low viewing angle of the beach are presented, as well as data processing options and recommendations for the potential wider adoption of this largely untapped coastal monitoring resource.

Frihy, O.E.; Deabes, E.A., and Helmy, E-El.D.F., 2016. Compatibility analysis of dredged sediments from routine pathways and maintenance of harbor's channels for reuse in nearshore nourishment in the Nile Delta, Egypt.

Dredged seabed sediments from Nile Delta pathways and maintenance of harbor channels were analyzed for compatibility with samples from five eroding beaches as potential borrow material for nearshore nourishment. Dredging sites were essentially centered at Abu Qir bay, Rosetta estuary, Burullus harbor, the Damietta approach channel, and El Gamil inlet near Port Said. Compatibility analysis of core and seabed samples collected from the dredging areas with the native eroding beaches was performed using multiple methods, including graphical comparison of grain size distributions (scatter plots, cumulative curves, and frequency curves), overfill (R_A), and renourishment (R_J) factor models, the “half-life time” of the specified beach fills, and the volume of borrow sediment required to maintain equilibrium in the beach/littoral system. Results indicate that the compatibility of the dredged borrow sediments to the native material varies locally from fairly compatible (Rosetta estuary, Burullus harbor, Damietta approach channel, and El Gamil inlet) to incompatible (Abu Qir bay). Because of the wide range of grain-size distribution of dredged sediment, only 18–51% of the sand fractions evaluated were compatible with native beaches. However, excessive volumes of dredged sediment can compensate for dredging sites with low proportions of sand, estimated between 2.5 and 4.7 times the volume required using compatible materials to maintain the equilibrium profile. Furthermore, the frequency of nourishment operations would be 0.33 to 3.0 times more often than would be required with a fully compatible borrow material. For economic, environmental, and technical considerations, engineering procedures for nearshore nourishment (underwater nourishment) are recommended as an appropriate mitigation to eroding coastlines in the Nile Delta.

Curtiss, D. and Pierce, A.R., 2016. Evaluation of wintering waterbird habitats on Louisiana barrier islands.

Louisiana's barrier islands provide unique habitats for waterbirds throughout the year. Unfortunately, barrier islands such as those within the Isles Dernieres Barrier Island Refuge (IDBIR) are rapidly degrading, and critical waterbird habitats are disappearing. The majority of waterbird research projects in the northern Gulf of Mexico have focused on important breeding habitats, but little information exists on preferred habitats during the nonbreeding wintering period. The goal of this study was to identify important waterbird habitats on barrier islands during the nonbreeding period to enhance barrier island management for year-round use by waterbirds. Biweekly surveys were conducted at the IDBIR during the 2010–2011 and 2011–2012 nonbreeding seasons to determine waterbird use of beach habitats. Habitat maps of the IDBIR were also created to calculate bird densities and species richness among habitat types, including bayside intertidal, flats, gulfside intertidal, nonintertidal, and rock structures. This study also quantified availability of food resources by collecting benthic core samples from substrates at each habitat type. Forty-seven waterbird species were observed during waterbird surveys. Wine Island had the greatest species richness and bird density (5.5 species/ha and 325.6 birds/ha) among the islands, as well as the greatest density of foraging waterbirds. Rock structures and gulfside intertidal habitats had the greatest species richness and bird densities among habitat types. East and West Raccoon islands and intertidal habitats had the greatest availability of invertebrate prey. There was a moderate correlation (r² = 0.32) between invertebrate biomass and abundance of foraging shorebirds. It is recommended that future restoration projects provide wide, expansive intertidal habitats to enhance critical wintering habitats for waterbirds.

Restrepo, J.C.; Schrottke, K.; Traini, C.; Ortiz, J.C.; Orejarena, A.; Otero, L.; Higgins, A., and Marriaga, L., 2016. Sediment transport and geomorphological change in a high-discharge tropical delta (Magdalena River, Colombia): Insights from a period of intense change and human intervention (1990–2010).

There is strong indication that environmental changes and human interventions have affected freshwater discharge and sediment flux in the Magdalena River (northwestern South America) within the period from 1990 to 2010. Thus, stream flow, suspended sediment load (SSL), and riverbed dynamics were analysed in this study for estimating changes in the suspended sediment transport regime as well as of erosional/depositional patterns in different zones of the delta. It can be shown that stream flow increased at a higher rate than suspended sediment transport, promoting changes in the sediment transport regime. Erosion appeared at the mouth/frontal bar and the outlet zones and modified the sedimentary balance within the prodelta in the early 2000s. There is indication that cycles of erosion and accretion were controlled by the magnitude of fluvial discharge and riverbed scouring in the river outlet, whereas effluent diffusion and sediment dispersion were dominant in the delta front. High freshwater discharge, as buoyancy inputs, promoted the transfer of sediments from the river channel to the outer prodelta through the upper layers of the water column. Total sediment accumulation in the delta corresponded to <5% of the annual mean SSL of the Magdalena River. Overall, delta morphology remained relatively stable, experiencing a slow progradational state with highest sedimentation rates (≤1430 mm y⁻¹) in the deepest zones.

Postacchini, M.; Russo, A.; Carniel, S., and Brocchini, M., 2016. Assessing the hydro-morphodynamic response of a beach protected by detached, impermeable, submerged breakwaters: A numerical approach.

Coastal areas host a large fraction of the world's population and are exposed to natural extreme events, which are a serious threat to human life, as well as to economies. For this reason, sea storms are increasingly the object of studies, and the design of traditional coastal defenses is being carried out in conjunction with modeling analyses. Relying on numerical simulations performed by means of an innovative shallow-water hydro-morphodynamic model, the present work explores the overall response of a protected beach to sea storms. Numerical tests evaluate the effects of sea states extracted from realistic sea storms having different spectral characteristics, as well as the influence on beach morphology of positioning shore-parallel, impermeable, submerged breakwaters. Simulation results revealed that, while erosion/accretion patterns depend weakly on the different sea state conditions, the morphodynamics induced around the barriers is strongly influenced by the breakwaters' positioning. More specifically, at least for the forcing here analyzed, bed variations were shown to increase when the structures are progressively located offshore; on the other hand, the swash zone morphology seems to be only weakly influenced by the positioning of the breakwaters. We also observed that for an increasing extension of the volume over which dissipative breaking mechanisms occur, a decreasing inshore erosion is accompanied by an equally fast decrease of offshore erosion. Analysis of the vorticity fields shows that breakwaters placed far from the shoreline induce an evolution of the vortices generated by breaking waves rather different from the one due to breakwaters placed closer to the shoreline (which can induce seaward flows through the gap, like rip currents).

Nguyen, P. T.; Ruangchuay, R., and Lueangthuwapranit, C., 2016. Physical responses and growth on tissue culture of agarophytic seaweed, Gracilaria fisheri (Xia and Abbott) Abbott, Zhang, and Xia (Gracilariales, Rhodophyta).

This study on Gracilaria fisheri tissue culture was aimed at optimizing the growth conditions for strain maintenance. Tissue culture experiments were conducted in four selected influential factors: salinity, fragment length, growing zone, and propagule density. Each experiment was subsequently completed with three replications, and the best result was used in the next study. The experiment on fragment length was conducted from 1 to 5 cm of subapical segments. The study on different salinity levels was completed in the range of 15–35 ppt. Different zones of tissues were selected as apical, subapical, and basal fragments for the next study. The study on different propagule densities was conducted from 1 to 8 g L⁻¹. Each experiment was done for 40 days under 25 μmol m⁻² s⁻¹ of light intensity and 12L:12D of photoperiod at a temperature of 25 ± 2°C. The result showed that optimal conditions for G. fisheri tissues existed at 2 cm of segment length under 20 ppt salinity and were part of the tissue from the apical zone and 1 g L⁻¹ density. Under optimal conditions, the daily growth rate of G. fisheri tissues was 6.5% day⁻¹, and the final biomass was increased 12.4 times compared to the initial biomass. One finding of the study on physical performance of G. fisheri tissue was that only apical tissues grew with apicobasal polarity. The number and length of branches were seven branches per cm and 0.8 cm, respectively. Also, G. fisheri tissue that expressed as a stenohaline species was rather more affected by salinity than the other factors.

Sim, S.Y. and Huang, Z., 2016. An experimental study of tsunami amplification by a coastal cliff.

There is a general lack of understanding of the effects of coastal cliffs or other complex topography features on tsunami run-ups and tsunami heights onshore. We experimentally investigated several factors that might influence the amplification of onshore tsunami heights in the presence of a coastal cliff through a set of wave flume tests. The cross-shore bed profile used in the experiment was modeled using a composite slope made of three sections, with the gentlest section onshore to replicate the beach. A structure with an adjustable foreslope was mounted onto the beach section to model a coastal cliff. From our experimental results, a critical angle of about 45° was identified: the amplification factor increased with the cliff slope for cliffs gentler than 45°, and cliffs steeper than 45° gave more or less constant amplification factors for a given wave condition. The largest amplification factor found in this study is about 2.8; if water splashing was considered, the amplification factor would be even larger.

Cattani, P.E. and Lamour, M.R., 2016. Considerations regarding sedimentation rates along the E-W axis of the Paranaguá Estuarine Complex, Brazil: A bathymetric approach.

The sediment dynamics in coastal regions are a result of the coexistence of fluvial, estuarine, deltaic, and shelf depositional environments, as well as the relation among the processes of sediment transport. The Paranaguá Estuarine Complex (PEC) presents different characteristics along its E-W axis, containing areas of port activity. The aim of this study was to identify critical areas of estuarine sedimentary infill and determine their rates and relationships regarding the estuarine environment features. This study employed 38 bathymetric surveys conducted between 1999 and 2008 arranged sequentially from the head of the estuary to the inner continental shelf. Initially, these surveys were grouped chronologically and according to their areas of overlap. Later, they were divided according to grain size and short-term hydrodynamic behavior in four sectors. The sedimentation rates in a portion of the estuary head were 0.60 cm·mo⁻¹·km⁻², whereas in the turbidity maximum zone (TMZ), they were approximately 0.06 cm·mo⁻¹·km⁻², and in the estuary mouth, they were 0.08 cm·mo⁻¹·km⁻². On the inner continental shelf (ICS), a critical area of silting on the terminal lobe of the ebb tidal delta was quantified as 0.56 cm·mo⁻¹·km⁻². The differences among silting rates along the PEC are related to the sediment supply for each sector of deposition, as well as the acting hydrodynamic forces. The higher rates found in the inner portion of the estuary may be the result of the advance of river deltas at the head of the estuary, associated with shallow depths and low energy in tidal currents. In the TMZ, silting occurs heterogeneously, with erosion areas associated with rock formations. On the ICS, the area of critical concern in sediment dynamics is the ebb tidal delta, located at the mouth of the PEC, where shallow areas amplify the power transport of the wave energy from the S-SE quadrant , and this energy decreases when entering the channel, allowing deposition.

Zapperi, G.; Pratolongo, P.; Piovan, M.J., and Marcovecchio, J.E., 2016. Benthic-pelagic coupling in an intertidal mudflat in the Bahía Blanca estuary (SW Atlantic).

Benthic-pelagic coupling was evaluated in a shallow, turbid, and nutrient-enriched estuary in the SW Atlantic. We analyzed the annual trends in turbidity, nutrients, and chlorophyll a (Chl a) concentration in the water column and related those changes to benthic fluxes of dissolved inorganic nutrients, estimated through microcosm incubation experiments, as well as seasonal variations in the abundance and composition of macrobenthic communities. The intertidal mudflats of the estuary are characterized by the presence of two subsystems defined by their macroecological features: crab beds, steep areas dominated by the burrowing crab, and Laeonereis flats, plain areas with low crab burrow density. Peak Chl a concentration in the water column occurred in July after turbidity reached its minimum value in June. Dissolved nutrients decreased after the peak of Chl a. Benthic fluxes of into the water column were very high after the diatom bloom in the Laeonereis flats, whereas the crab beds performed as sinks. Both subsystems were sinks of + before the bloom, and fluxes reversed in the postbloom period. The crab Neohelice granulata and the polychaete Laeonereis acuta were the most represented macrobenthic species in both subsystems. Density of L. acuta in Laeonereis flats was highest in June, whereas that of N. granulata in the crab beds was highest in December. These changes in abundance coincide with changes in benthic fluxes. These results suggest that benthic-pelagic coupling, mediated by biological activity, may play a significant role in creating the window of lower turbidity that allows phytoplankton blooms. As the bloom develops, dissolved nutrients in the water column are consumed, and organic matter is produced. As a counterpart, the local coupling between remineralization in the sediment surface and the benthic flux to the water column as dissolved nutrients allows the recovery of nutrient levels and supports primary production in the forthcoming cycle.

Reyes-Mendoza, O.; Mariño-Tapia, I.; Herrera-Silveira, J.; Ruiz-Martínez, G.; Enriquez, C., and Largier, J.L., 2016. The effects of wind on upwelling off Cabo Catoche.

Upwelling of cold, nutrient-rich waters at the NE corner of the Yucatan Peninsula is known to enhance productivity over the Yucatan Shelf, fueling fisheries and harboring the largest global aggregation of whale sharks. Nevertheless, the physical processes that control this upwelling and the spreading of upwelled waters onto the Yucatan Shelf are not well known, particularly near the coast. In this study, upwelling behavior close to the coast was characterized, and the contribution of wind was assessed. Time series of wind, air and ocean temperatures, sea level, and current velocities from two moorings were analyzed. Wavelet transforms showed cold-water pulses with timescales that vary across the seasons and also between the shallower site (8 m) and the deeper site (12 m), with a broader range of periodicities observed further offshore. These upwelling pulses do not correlate simply with wind-driven Ekman transport, suggesting that the process is not locally controlled. Temperature covaried with horizontal currents, suggesting an advective mechanism, which is related to the wind. Although local winds may at times enhance the nearshore intrusion of upwelled waters along the northern shore of the Yucatan Peninsula, more important in these data was the disappearance of cold waters during northerly winds. This appears as an interruption of upwelling, which was highly coherent at periods of 7 to 16 days. These northerly winds are typical from October to February, but can occur at other times as well, for example during an intensive field campaign in April 2012.

Ruiz-Martínez, G.; Mariño-Tapia, I.; Mendoza Baldwin, E.G.; Silva Casarín, R., and Enríquez Ortiz, C.E., 2016. Identifying coastal defence schemes through morphodynamic numerical simulations along the northern coast of Yucatan, Mexico.

A beach segment on the northern coast of the Yucatan Peninsula, where sandy beaches have widespread erosion problems, was studied with morphodynamic numerical simulations to identify the most appropriate protection scheme for mitigating coastal erosion in the region. The numerical model Delft3D was used to model hydro-morphodynamic patterns. Three types of solution were simulated: (1) beach nourishment only, (2) beach nourishment and groynes (linear, Y- and T-shaped), and (3) beach nourishment and offshore breakwaters. Measured time series of wind, sea level, and shelf currents were fed into the numerical model. Morphodynamic simulations were validated by comparing the modelled volumetric changes with those observed from beach profiles. The morphodynamic evolution was evaluated using bottom depth contour maps, and a volumetric sand balance and sand flux analysis identified which scheme retained more sand in the littoral system. The protection scheme with linear groynes showed greater sand retention in the short term, but in the medium term, this solution enhanced beach erosion. The numerical simulations showed that beach nourishment performs better than linear groynes in the long term and have beneficial downdrift effects. Nevertheless, T groynes had the smallest loss of sand nourishment in the short and long terms, suggesting that this scheme could best retain sand, although exacerbating erosion in downdrift beaches. From a cost analysis perspective, T groynes show a lower maintenance cost than beach nourishment and linear groynes.

Charlier, R. H. and Charlier, C. P., 2016. Lowlands sixteenth century cartography: Mercator's birth pentecentennial.

The 500th anniversary of Mercator's birth ought to be celebrated as a milestone in the history of cartography and navigation. Not because he is one of the mapmakers of the 16th century, but because he contributed perhaps most significantly to the progress of navigation. Although he was born in a small Flandrian town, his name remains associated with Antwerp. His studies at the famed university of Louvain (Leuven-Lovanium) were financed by a clerical relative, and his work was buttressed by that of Ortelius, his associate. The Mercator projection proved to be a priceless gift to ship captains. Earlier in the same century a painter of renown, Peter Pourbus, in the service of the Sire of Moerbeke and of Holy Roman Emperor Charles V, engaged in mapmaking using an approach worthy of modern cartographers. In the northern Lowlands, mapmaking had already made great steps forward in earlier times.

Kearney, M.S. and Turner, R.E., 2016. Microtidal marshes: Can these widespread and fragile marshes survive increasing climate–sea level variability and human action?

Microtidal organic marshes, where mineral inputs are low to negligible and the dominant organic inputs to vertical accretion are subject to substantial losses from decomposition, may be particularly at risk from future environmental change. Generally occurring along coasts with small tidal frames (<2-m tidal range, or microtidal), these marshes are characterized by average flood velocities too low to import appreciable mineral sediment into marsh interiors. Their reliance on organic accumulation makes them vulnerable to any factor that affects annual biomass inputs, whether by animal (e.g., waterfowl or snails) overgrazing, damage to physiological functioning (substrate anoxia, excess hydrogen sulfide, and nutrient concentrations), or erosion from coastal storms. The sudden dieback phenomenon highlights differences between microtidal marshes and those in larger tidal frames. Despite a number of proposed causes, dieback in microtidal systems can resemble classic interior pond formation from rapid sea level rise. By comparison, in marshes where tidal ranges exceed 2 m, it commonly involves wholesale plant loss across a wide area, whether in shoreline areas only or across the breadth of the marsh. Increasing sea level variability, with more frequent accelerations and decelerations, along with exceptional high and low stands, could add a critical element to the matrix of stressors (many of human origin) to fragile microtidal marshes. These marshes, therefore, could be lost at faster rates than expected from future sea level rise scenarios. Society should be rightly concerned about whether microtidal marshes can endure future sea level rise, as well as whether they can survive our stewardship now.

Palalane, J.; Larson, M.; Hanson, H., and Juízo, D., 2016. Coastal erosion in Mozambique: Governing processes and remedial measures.

Mozambique's 2800-km-long coastline comes with associated vulnerability to coastal erosion, their processes, and resulting evolution. In fact, coastal erosion has been identified as a dominant phenomenon in the Mozambican coastal system. It is driven by a combination of natural processes and anthropogenic actions. Despite the significant vulnerability and the implications to national economic development, very few technical or scientific studies are available about the country. This paper contributes with insights about the erosion of the vast Mozambican coast by analysing the dominant threats to the coast. The analysis is based upon a detailed review of the situation at five locations on the Mozambican coast already experiencing shoreline recession. The study also analyses the existing legal framework and institutional arrangement for coastal planning and management, as well as critical aspects for effective implementation of coastal protection initiatives. Further, historical and current practices in coastal protection are evaluated. In conclusion, coastal erosion due to natural causes will continue to challenge coastal planners and managers in Mozambique, compounded by a lack of planning or poor planning for coastal developments and resulting anthropogenic impacts. Strong coastal retreat rates exceeding 1 m/y have been observed in some places, as compared to 0.4 m/y due to natural causes. To manage coastal erosion in a more integrated way, there is a need to focus on improving the existing legal instruments and the coordination among all the stakeholders, and to increase the knowledge base. There is also a need to disseminate information among decision makers and coastal planners, specifically, that soft coastlines demand soft protection measures, as hard and semihard structures have been prioritised in coastal protection interventions. In addition, the planning for coastal developments should ensure a better integration of environmental, social, and financial components, and always consider the impact of local solutions at wider temporal and spatial scales.

Sommerfield, C.K., 2016. Qualities and limitations of fluvial suspended sediment data published by the United States Geological Survey.

Fluvial suspended sediment concentration (SSC) data published by the United States Geological Survey (USGS) are frequently used to address questions of sediment delivery to estuaries and coasts. Despite the availability of USGS reports detailing methods of sample collection and data processing, many end users remain misinformed about the characteristics and limitations of these data. Two types of USGS-SSC data are available for stream gauging stations: (1) discrete samples and (2) daily record. Discrete samples are laboratory measurements of SSC from water collected at a stream gauging station. In contrast, daily-record data are interpolations of SSC from a smaller number of discrete samples available for a station. A potential source of confusion arises because both types of USGS-SSC data are given the identical description (suspended sediment concentration, mg/L) and parameter code (80154) in the national database. Although the daily-record series for a station is derived from actual samples, discrete and daily SSC values for the same date of record are not always strongly correlated because of factors related to sampling and data processing. As shown in this paper, discrete-sample SSC data series for some stations are inhomogeneous and biased because of changes in USGS sampling practices over the decades, thereby limiting the possible end uses of the data. Ultimately it is up to users to determine which type of SSC data are best suited for a particular application and whether the statistical properties of a data set are conducive to applications such as trend analysis.

Zhao, Z.; Zhao, J.; Xin, P.; Jin, G.; Hua, G., and Li, L., 2016. A hybrid sampling method for the fuzzy stochastic uncertainty analysis of seawater intrusion simulations.

The traditional fuzzy stochastic hybrid method requires hundreds or even thousands of simulations to obtain a statistically stable result, which is a significant challenge for some nonlinear problems, such as simulating seawater intrusion. A hybrid sampling (HS) method was developed based on the Monte Carlo (MC) uncertainty analysis whose input parameters are characterized by both stochastic variables and fuzzy numbers. The HS method is a restricted sampling method that fully captures statistical information on the stochastic variables and the fuzzy memberships provided by fuzzy numbers. In HS, samples of stochastic variables and fuzzy numbers are generated using Latin hypercube sampling and restricted stratified sampling, respectively. After they have been generated, samples of different variables are paired to form inputs in a restricted manner for the simulations. This ensures that the samples are distributed across each variable's range of uncertainty. The correlations between different variables are also controlled during the restricted sampling process. The simulations of seawater intrusions show that the means and variances of the samples generated using the HS method converge more quickly compared with those generated using a random sampling method. The number of MC simulations required was significantly reduced by using the HS method, which improves the effectiveness of predicting seawater intrusion for the management of coastal aquifers.