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Mark Stolt, Michael Bradley, Jim Turenne, Maggie Payne, Eric Scherer, Giancarlo Cicchetti, Emily Shumchenia, Marisa Guarinello, John King, Jon Boothroyd, Bryan Oakley, Carol Thornber, Peter August
In order to effectively study, manage, conserve, and sustain shallow-subtidal ecosystems, a spatial inventory of the basic resources and habitats is essential. Because of the complexities of shallow-subtidal substrates, benthic communities, geology, geomorphology, and water column attributes, few standard protocols are fully articulated and tested that describe the mapping and inventory processes and accompanying interpretations. In this paper, we describe a systematic approach to map Rhode Island's shallow-subtidal coastal lagoon ecosystems, by using, integrating, and reconciling multiple data sets to identify the geology, soils, biological communities, and environments that, collectively, define each shallow-subtidal habitat. We constructed maps for these lagoons via a deliberate, step by step approach. Acoustics and geostatistical modeling were used to create a bathymetric map. These data were analyzed to identify submerged landforms and geologic boundaries. Geologic interpretations were verified with video and grab samples. Soils were sampled, characterized, and mapped within the context of the landscape and geologic boundaries. Biological components and distributions were investigated using acoustics, grab samples, video, and sediment profile images. Data sets were cross-referenced and ground-truthed to test for inconsistencies. Maps and geospatial data, with Federal Geographic Data Committee (FGDC)-compliant metadata, were finalized after reconciling data set inconsistencies and made available on the Internet. These data allow for classification in the revised Coastal and Marine Ecological Classification Standard (CMECS). With these maps, we explored potential relationships among and between physical and biological parameters. In some cases, we discovered a clear match between habitat measures; in others, however, relationships were more difficult to distinguish and require further investigation.
This paper introduces the recently developed resource “Characteristics of the Shoreline Change along the Sandy Beaches of the State of Florida: An Atlas” (available on the web). The shoreline positions on which the Atlas is based encompass 25 coastal counties extending over 1162 km of shoreline and averages over almost 140 years. The data were analyzed over three different periods (early, recent, and total) to distinguish mainly beach nourishment and sand bypassing projects, primarily in the recent period. The east and west coastlines of Florida have advanced significantly in the recent period relative to the early period, with the recent and early period average shoreline change rates being 23 cm/y and 18 cm/y on the east coast and 27 cm/y and −7 cm/y on the west coast, respectively. This improvement is attributable to, in part, the large quantities of sand placed during nourishment and sand bypass projects. Shoreline changes in the vicinity of the 58 inlets were examined, and it was found that shoreline fluctuations decreased significantly with increasing distance from the inlets, and that sand bypass and nourishment projects reduced the shoreline variability during the recent period.
Temporally and spatially repeated patterns of wetland erosion, deformation, and deposition are observed on remotely sensed images and in the field after hurricanes cross the coast of Louisiana. The diagnostic morphological wetland features are products of the coupling of high-velocity wind and storm-surge water and their interaction with the underlying, variably resistant, wetland vegetation and soils. Erosional signatures include construction of orthogonal-elongate ponds and amorphous ponds, pond expansion, plucked marsh, marsh denudation, and shoreline erosion. Post-storm gravity reflux of floodwater draining from the wetlands forms dendritic incisions around the pond margins and locally integrates drainage pathways forming braided channels. Depositional signatures include emplacement of broad zones of organic wrack on topographic highs and inorganic deposits of variable thicknesses and lateral extents in the form of shore-parallel sandy washover terraces and interior-marsh mud blankets. Deformational signatures primarily involve laterally compressed marsh and displaced marsh mats and balls. Prolonged water impoundment and marsh salinization also are common impacts associated with wetland flooding by extreme storms. Many of the wetland features become legacies that record prior storm impacts and locally influence subsequent storm-induced morphological changes. Wetland losses caused by hurricane impacts depend directly on impact duration, which is controlled by the diameter of hurricane-force winds, forward speed of the storm, and wetland distance over which the storm passes. Distinguishing between wetland losses caused by storm impacts and losses associated with long-term delta-plain processes is critical for accurate modeling and prediction of future conversion of land to open water.
Exposure to solar radiation and tidal inundation are important factors for a wide variety of chemical and ecological processes in coastal ecosystems. Accurate quantification of these factors is often difficult on a local scale. To address this research gap, a remote-sensing approach was developed to model inundation and radiation characteristics within an intertidal zone located in the Minas Basin (Bay of Fundy, Nova Scotia, Canada). A light detection and ranging (LIDAR)–derived elevation model was subjected to tidal modelling based on hourly sea level predictions and solar modelling based on sunrise and sunset times for 2009. Model results indicated an intertidal zone of 145.8 km2 with an elevation between −6.9 m and 6.8 m. The intertidal zone was determined to contain three unique wetland classes: (1) 4.4 km2 of high salt marsh, dominated by Spartina patens; (2) 5.0 km2 of low salt marsh, dominated by Spartina alterniflora; and (3) 63.1 km2 of nonvegetated marine flat (73.3 km2 unclassified intertidal). Detailed exposure characteristics were calculated for each of the classes within the intertidal zone at 10-cm vertical intervals. Exposure calculations for 2009 showed that an average of 4.2 km2 of salt marsh were exposed to solar radiation and 8.4 km2 were exposed to the atmosphere each hour. Similarly, 11.7 km2 of marine flat were exposed to solar radiation and 22.9 km2 were exposed to the atmosphere each hour. The developed remote-sensing techniques successfully established intertidal zones, uniquely identified wetland classes, and modelled inundation and solar exposure characteristics within the study area.
Hypoxia has become an overwhelming phenomenon in the coastal environment off the Changjiang (Yangtze River) estuary. Seasonal data were obtained in the Changjiang estuary during 2003, 2004, 2005, and 2009 and during an additional cruise between April and May in 2007 on the dissolved oxygen distribution of the bottom water, on hypoxic events, and on their potential causes. Dissolved oxygen was less than 3.0 mg L−1 in the summer and less than 5.0 mg L−1 in the spring and autumn in the topographic trough and was generally lower than that in the surrounding bottom water of the Changjiang estuary. In the summer, there was a positive correlation (r2 = 0.57) between dissolved oxygen concentration and temperature, contrary to the observations in the autumn and winter. A strong halocline and thermocline appeared in the spring and summer. A change in temperature structure was observed in an additional cruise in 2007; the vertical transport of dissolved oxygen flux, which was restricted by stratification, reached 2.77 g m−2 d−1. Large nutrient inputs and phytoplankton seem to contribute to hypoxia in the Changjiang estuary.
An emerged, Quaternary, marine terrace sequence has been investigated near Trabzon, Turkey, along a ∼20-km-long stretch of the coast of the southeastern Black Sea. The sequence includes seven principal marine terraces. The terraces are frequently compound and include up to three second-order marine terraces. The upper shoreline angles of the main terraces were found at the following maximum elevations above mean sea level: 3 ± 0.5 m (TH), 12 ± 3 m (T1), 36 ± 2 m (T2), 79 ± 9 m (T3), 120 ± 3 m (T4), 138 ± 10 m (T5), and 260 ± 25 m (T6). Fossil bivalves and gastropods from the TH, T1, T2, and T3 deposits have been dated by Electron Spin Resonance (ESR). The results show that the ages of the deposits from the TH, T1, T2, and T3 terraces are 5.141 ± 0.294 ka, 124.8 ± 26.0 ka, 292.5 ± 49.8 ka, and 407.998 ± 67.475 ka, respectively. Consequently, we correlate TH, T1, T2, and T3 to marine isotope stage (MIS) 1, 5e, 9, and 11, which correspond to ∼5, ∼123, ∼321, and ∼400 ka highstands, respectively. Estimated uplift rates deduced from the elevations of T1, T2, and T3 are 0.07 ± 0.05, 0.10 ± 0.02, 0.17 ± 0.03 mm/y or m/ka. These results show nonsteady, long-term uplift rates. Extrapolation of the oldest uplift rate (i.e., determined on the highest dated terrace) shows that in the region of Trabzon, Turkey, coastal, positive, vertical deformations are recorded at ∼2 Ma, which corresponds to the extrapolated age of the highest terrace in the sequence. Comparison with other sequences on the Black Sea coast reveals a rather weak uplift in this zone, which can be considered significative for the recent uplift of the Eastern Pontides.
KEYWORDS: hydrodynamic modeling, water quality, environmental hydraulics, monsoon wind–induced water transport, Hong Kong, Pearl River Estuary, wind mixing
In subtropical coastal waters around Hong Kong, a well-mixed water body is usually observed after typhoons or strong easterly wind events in summer. A calibrated three-dimensional (3-D) hydrodynamic model for the Pearl River Estuary (Delft3D) was applied to study the physical hydrography of Hong Kong waters and its relationship with wind events in the summer wet season. The general 3-D hydrodynamic circulation and salinity structure in the partially mixed estuary are presented here. The effect of wind on vertical mixing was studied for two representative wind directions (NE and SW) and three wind speeds (5, 7.5, and 10 m/s). The computations show that: (i) in general, in the summer wet season, the river plume moves into the western waters of Hong Kong due to the SW monsoon winds, and the current flow is mainly from W/SW to E/NE in the southern Hong Kong waters; the salinity vertical profile indicates that the water is strongly stratified; (ii) a strong SW wind pushes the river plume into a narrow band and decreases the salinity of the surface water in the estuary and its neighboring region; it may also enhance the mixing in the upper layer of water column, but the whole water body is still stratified; and (iii) a strong NE wind pushes the river plume westward away from Hong Kong waters, and more saline coastal waters enter Hong Kong waters; the water only becomes vertically well mixed after a 10 m/s NE wind blows for 5 d, but wind speeds of 5 and 7.5 m/s do not result in the same extent of mixing. We also examined the role of wind in an episodic storm event in August 2003. The strong SE wind from 23 to 26 August strongly mixed the water column. The moderate to weak NE wind during 16–20 August and the spring tide also contributed to the vertical mixing.
St. Augustine Inlet is located on the NE coast of Florida, connecting the Atlantic Ocean to the Tolomato and Matanzas rivers. The inlet is unique because it was relocated in the 1940s, resulting in considerable perturbations to the adjacent coastal system, especially the downdrift (southern) shoreline. The relatively low, permeable, and short north jetty has allowed sediment to move around, through, and over the jetty, resulting in deposits on the interior lagoon/bay and on the ebb shoal system. Since 2001, dredging has occurred on the ebb shoal and bypassed to the downdrift side of the inlet on St. Augustine Beach. At present, dredging and bypassing have occurred on an irregular schedule, although questions remain about what a reasonable schedule would be to prevent excessive problems on both the updrift and downdrift beaches. This article presents an evaluation of a potential approach for use in addressing the dredging and bypassing schedules to assess how various intervals of dredging/bypassing can affect an idealized downdrift beach having the same net sand transport as that near the St. Augustine Inlet.
Bedform (ripple) geometry is an important feature in the nearshore that can significantly enhance wave energy dissipation. Ripples regulate wave transformation and influence the sediment transport phenomenon. These issues are of particular importance when determining beach erosion and investigating other coastal processes. Although numerous studies have addressed the issue of bedform geometry under surface gravity waves, no single model is considered adequate. The relative roughness and subsequent wave energy dissipation are governed by attributes that include ripple height and wavelength. The comparatively large wave tank facility at Davidson Laboratory (Stevens Institute of Technology, Castle Point on the Hudson, Hoboken, New Jersey) provided an ideal opportunity for investigating bedform features for a flat bed, as well as the novel study of a sloped sediment bed. Our results provide new data that strengthen prior relationships and demonstrate that a sloped surface may be modeled in a similar fashion to a flat sediment bed. We have successfully compared irregular waves from the laboratory to field measurements and selected an existing model that is consistent with our data. Perhaps one of the most significant conclusions from this research is that the identified models for ripple dimensions on the flat surface predict values for bedform geometry on the sloped surface as well.
This article addresses the problem of sedimentation at the entrance of a harbour by evaluating and understanding the sediment dynamics in the adjacent beaches. The results of the methodology applied to acknowledge the beaches' sediment dynamics were used to diagnose the problem's cause and to interpret its evolution. The methodology includes analysis of data from a monitoring programme and process-based mathematical modelling of the alongshore and cross-shore beach dynamics. The integration of both allowed the authors to investigate the hydromorphological behaviour of the harbour-adjacent beaches and to conclude that (i) the harbour and adjacent beaches are a single morphological system, and thus require integrated management; (ii) the study area is exposed to a seasonal wave regime, which induces a local sediment transport pattern and consequently the main seasonal morphological characteristics of the study area; and (iii) the process of sand accumulation at the harbour entrance is irreversible without human intervention. Because harbours should be designed and constructed based on two criteria—capacity of depth self-maintenance and integration, with minimum impact on the local morphodynamics—this study highlights the need for monitoring and identifying the total extension of the active beach, particularly in coastal environments with seasonal hydromorphological variations, before deciding on harbour layout relative to the sedimentary littoral transit.
Coastal marsh habitat and its associated vegetation are strongly linked to substrate elevation and local drainage patterns. As such, accurate representations of both the vegetation height and the surface elevations are requisite components for systematic analysis and temporal monitoring of the habitat. Topographic Light Detection and Ranging (LIDAR) data can provide high-resolution, high-accuracy elevation measurements of features both aboveground and at the surface. However, because of poor penetration of the laser pulse through the marsh vegetation, bare-earth LIDAR elevations can be markedly less accurate when compared with adjacent upland habitats. Consequently, LIDAR ground-elevation errors (i.e., standard deviation [SD] and bias) can vary significantly from the standard upland land-cover classes quoted in a typical data provider's quality-assurance report. Custom digital elevation model (DEM) generation techniques and point classification processes can be used to improve estimates of ground elevations in coastal marshes. The simplest of these methods is minimum bin gridding, which extracts the lowest elevation value included within a user-specified search window and assigns that value to the appropriate DEM grid cell. More complex point-to-point classification can be accomplished by enforcing stricter slope limits and increasing the level of smoothing. Despite lowering the spatial resolution of the DEM, the application of these techniques significantly improves the vertical accuracy of the LIDAR-derived bare-earth surfaces. By employing the minimum bin technique to the bare-earth classified LIDAR data, the overall bias in the resultant surface was reduced by 12 cm, and the vertical accuracy was improved by 8 cm when compared with the “as-received” data.
Glaciers have pronounced long- and short-term effects on nearshore marine ecosystems. Concerns exist about possible changes that may occur to nearshore habitats with the pronounced climatic alterations in subarctic and high-latitude environments. The present research studied the effects of glacial discharge on kelp bed community structure by comparing environmental conditions on one more exposed and one less exposed shore in a subarctic Alaskan estuary. Inorganic sedimentation, abrasion, and percent sand/silt substrate were significantly higher on the more exposed shore than the less exposed shore. Light intensity, salinity, nitrate concentrations, and hard substrate cover were significantly lower on the more exposed shore. Kelp bed communities on the more exposed shore contained only one kelp species, Saccharina latissima, versus five kelp species on the less exposed shore. Taxonomic richness and overall organism abundance were significantly lower on the more exposed shore. Salinity, nitrate, inorganic sedimentation, and abrasion were identified as important drivers of kelp communities that are dynamically influenced by glacial discharge. In contrast, other drivers, such as hard substrate and rugosity, reflect existing differences between the two shore environments that are not influenced on short timescales by glacial discharge. While it is currently difficult to separate the relative roles of these two types of drivers on kelp bed communities, increased rates of glacial discharge due to climate change may exacerbate specifically the effects of the dynamic drivers and further decrease species richness in kelp bed communities in high-latitude estuaries.
This study investigated the spatial and seasonal variations of nutrients, chlorophyll-a (Chl-a), particulate organic carbon, and dissolved oxygen at four stations around Masan Bay from February 2004 to February 2006. Nutrients showed large spatial and seasonal variations in the study area. Dissolved inorganic nitrogen and dissolved silicate concentrations were highest at inner Masan Bay, which was ascribed to the largest inputs of both nutrients from the lands among four stations. Dissolved inorganic phosphorus concentrations are highest at Hangam Bay, where a fertilizer plant caused serious soil pollution with the by-products of phosphate rocks. The extremely high Chl-a concentrations (>60 µg L−1) were observed at inner Masan Bay in July and attributed to the plentiful nutrients, high water stability, and longer residence time at this area during summer. Surface Chl-a concentrations displayed large seasonal variations at all stations, with high values in summer and low values in fall and winter. The lower Chl-a concentrations in fall and winter may be due to strong vertical mixing, which could transport phytoplankton below the euphotic depth, and as a result, constrained phytoplankton growth. Particulate organic carbon–to–Chl-a ratios varied from 59.8 to 121, with large spatial variation and small seasonal change. Hypoxia (<2 mg L−1) was observed at inner and outer Masan and Hangam bays during summer. Outer Masan Bay showed more severe hypoxia than inner Masan Bay in summer 2004 and 2005, which was probably because of the higher organic contents at the bottom sediments and deeper water depth. Despite construction of the Masan and Jinhae wastewater treatment plants, Masan and Hangam bays still received high loading of nutrients, and serious eutrophication was still observed at these bays.
Social, cultural, geographical, and ethical values are component parts of port heritage, but they are difficult to quantify and to encapsulate into the market system. To evaluate the economic value of ports, port heritage has to be regarded as an economic driver. This article suggests that tourist and historical patterns are one of the approaches that can encourage developers or investors to explore the potential business opportunities of port heritage. Because port heritage has a strong link to local character, the development of port heritage will, in turn, strengthen the local economy. Marketing and managing port heritage is a way to ensure the success of a tourist–historic scheme. Port heritage is a record of the human use of the sea in all its diversity over a range of timescales. Furthermore, the “maritime heritage image” itself has become a major economic resource, not only in what remains and continues to develop in specialist maritime communities but also in the museums, archives, restoration works, and elsewhere for educational and recreational purposes.
The vulnerability of a rocky cliff to direct wave attack is a function of its lithological, structural, and morphological characteristics. The intensity of wave attack at the cliff foot depends on incident wave characteristics, nearshore bathymetry, beach and shore platform topography, coastline orientation, storm surges, and tidal range. The main goal of this paper is to relate the role of wave action as a geomorphic process influencing coastal cliff erosion with the control imposed by lithological and structural characteristics. For that purpose, a numerical wave propagation model (STWAVE) was used to evaluate differences in breaking wave height and energy along the study area (Galé–Olhos de Água, South Portugal) for a set of representative wave conditions and compared with existing mass movement data. As the study area presents wide longshore variation in wave exposition and breaking wave energies, five sectors were defined with contrasting wave action. When the distribution of mass movements along the coast is analyzed without considering the lithological variation, there is no relationship between the number and displaced volumes of mass movements and wave energy for each sector, with the majority of the movements and the greater volumes occurring in the least energetic sector. Therefore, lithology represents the dominant control on mass movement occurrence. However, if lithological variation is controlled by analyzing only the most common lithology in the study area (Miocene carbonate rocks), spatial variations in nearshore wave energy driven by the interaction of wave conditions with coastline orientation are found to influence mass movement occurrence.
Os factores que condicionam a evolução de arribas rochosas são variados, incluindo processos continentais, marinhos e factores intrínsecos ao próprio substrato rochoso. Por exemplo, a vulnerabilidade das rochas ao ataque directo das ondas é igualmente função das suas características litológicas e estruturais. Por sua vez, a intensidade do ataque às arribas rochosas pelas ondas depende de características das ondas, da batimetria, da topografia das praias e plataformas de abrasão adjacentes, da orientação da linha de costa, da existência de sobreelevação do nível do mar e da amplitude das marés.
O sector costeiro de arribas rochosas do Algarve central (Galé a Olhos de Água), proposto para estudo, expõe principalmente a Formação Carbonatada de Lagos-Portimão, do Miocénico. Constitui excepção o sector entre as praias de S. Rafael e da Baleeira, onde as arribas litorais expõem margas do Cretácico e calcários do Jurássico. O principal objectivo deste trabalho é definir o papel da acção das ondas, como um processo geomórfico, na erosão de arribas costeiras e comparar com o controlo imposto pelas características litológicas e estruturais das rochas. Para tal, foi utilizado um programa de modelação da agitação marítima (STWAVE) para determinar diferenças nas características das ondas na rebentação, ao longo do troço costeiro em estudo. A altura e energia das ondas na rebentação foram obtidas para cada condição testada e foram comparadas com os dados de movimentos de massa existentes. Uma vez que a linha de costa da área de estudo mostra uma forte variação longilitoral em relação à sua exposição às ondas, foram definidos cinco sectores com diferentes orientações. Dada a orientação diferenciada dos troços e a variabilidade longilitoral nas geoformas que os constituem, foi possível analisar a frequência de ocorrência de uma dada geoforma ao longo de troços com igual litologia mas com diferente orientação à ondulação dominante.
Os resultados deste trabalho apontam para uma clara diferenciação energética entre troços costeiros, em função da sua orientação e do rumo de agitação (ex. SW versus SE). Quando se faz uma análise dos movimentos de massa sem considerar as variações litológicas, não se observa nenhum
Like most harbors, the Port of Ensenada, Mexico, is vulnerable to the accumulation of pollutants. A wave-driven seawater pump (Sistema de Bombeo por Energía de Oleaje [SIBEO]) is proposed to inject clean and oxygen-rich water from outside the Port to promote flushing in its more stagnant areas. Three-dimensional, numerical simulations with the Estuary and Lake Computer Model (ELCOM) were used to investigate the behavior, extent, and effect of the SIBEO inflow. Conservative tracer experiments indicate that the effect of the pump would spread through the pycnocline and become noticeable throughout the harbor within a month. The tracer method yields a bulk estimate of the flushing time for the port of approximately 4 days, although the spatial variability of the flushing is significant. The least-flushed areas of the harbor are its NE and SE corners, where greater concentrations of pollutants have been observed.
Environmental control is widely accepted as the principal structuring force of the macrobenthos on sandy beaches: abundance, biomass, and species diversity of benthic assemblages are closely linked to variations in environmental conditions. Thus, disturbance events that modify habitat properties in these ecosystems are hypothesized to translate into strong and consistent community-wide responses; this is the central hypothesis of this study, which was tested by examining trajectories of macrobenthic assemblages in relation to the experimental introduction of a pulse disturbance event that consisted of concentrated vehicle traffic (600 passes over 3 days) applied to the intertidal zone in a multiple before–after control-impact design. Small-scale spatial heterogeneity and short-term temporal variability were pronounced for all composite descriptors of assemblages (i.e., total abundance, species richness, and diversity) as well as community structure. The experimental pulse disturbance in the form of increased off-road vehicle traffic lowered macrobenthic densities by 27–52% and resulted in significant temporal shifts of assemblage structure. These biological responses were, however, not always unequivocally linked to the disturbance event in all cases, because background variation in the absence of experimental manipulation of traffic could be of comparable magnitude. Thus, human pulse disturbance effects can operate against a matrix of considerable natural spatiotemporal variability over small scales on sandy beaches. This heterogeneity has traditionally not been sufficiently incorporated into our understanding of the dynamics of the macrobenthos on sandy beaches and emphasizes the need for more experimental approaches on sandy shores.
The growth response and photosynthetic activity of Taxodium distichum in relation to the leaf and root Na content was assessed with the use of 2-year-old seedlings submerged in saline. Seedlings were submerged in water containing 0, 4000, and 8000 ppm NaCl during May, July, and September, respectively. Submergence and soil flooding with fresh water (control) did not inhibit vertical or lateral seedling growth. No morphological changes were observed during submergence in salt water; however, in July and September, leaf injury and shoot dieback were observed in the drained seedlings. Saline submergence in July and September inhibited photosynthesis and decreased the leaf and stem biomass but did not affect the root biomass. The seedling Na and K ion contents increased with increases in salt concentration; however, in May, the ion contents did not increase significantly. Such seasonal differences in ion content might lead to variations in the extent of leaf damage and growth inhibition after saline submergence in T. distichum seedlings.
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