Hyperspectral and sophisticated multispectral imagery are increasingly used to obtain detailed information on species composition, condition, biomass, and other characteristics of coastal marshes. However, how differing levels of tidal inundation affect the reflectance characteristics of emergent marsh vegetation remains not well documented. In 1994–1996, general reflectance spectra were collected for three common brackish marsh species with different canopy architectures (Schoenoplectus americanus, Spartina patens, and Spartina cynosuroides) in field experiments in which changing levels of tidal inundation were simulated in specially nonreflected enclosures. Reprocessing the data with software not then available has allowed greater delineation of variations in the data, especially in the red–near-infrared boundary, that previously could not be differentiated. Spectra for all three species showed significant reductions in near-infrared reflectance (900–1100 nm) with progressive substrate inundation, the sharpest decline occurring for S. americanus, for which the narrow, tapering culms allowed substantial submergence of total aboveground biomass (and greatly decreased leaf area index [LAI]) after water depths on substrates reached 15 cm. Increasing inundation produced a particularly significant change in the 700–825-nm band of the spectral curve. Maximum peak percent reflectance shifted as much as 40 nm in these wavelengths, with two maxima over 100 nm apart in wavelength appearing in both the S. americanus and S. patens curves at water depths >30 cm. Simulations of Landsat Thematic Mapper bands show that the Normalized Difference Vegetation Index (NDVI) is highly correlated with LAI and suggest that NDVI-based estimates for marsh biomass can be strongly influenced by the effects of marsh canopy submergence on LAI.

Harmonic analysis of the observed and simulated tides in the Mandovi and Zuari estuaries along the west coast of India was carried out. Tidal constituents derived from this process were analyzed to study the tidal asymmetry in these estuaries. Sea level observations during March–April 2003 at 13 stations in the Mandovi and Zuari estuaries were used for the harmonic analysis. Simulations of tides were carried out using a hybrid network numerical model. The model could well simulate the amplitude and phase of five major tidal constituents (K₁, O₁, M₂, N₂, S₂) in almost all stations in the Mandovi and Zuari estuaries. Both observations and simulations show that the amplitude and phase of major diurnal and semidiurnal constituents increase toward the upstream regions. The increase of this predominant species toward the upstream regions shows that the Mandovi and Zuari estuaries are not frictionally dominated estuaries because amplification due to geometrical effects cancels the decay in amplitude due to friction.

The rapid increase of the first and second harmonics of M₂ and compound tides inside the estuaries shows the nonlinear response of the Mandovi and Zuari estuarine systems to tidal forcing. The M₄/M₂ amplitude ratio indicates that the tide is subjected to more asymmetry in the Zuari than that in the Mandovi estuary. The increase of the first harmonic of M₂ and decrease of relative surface phase (2M₂–M₄) inside the Mandovi and Zuari estuaries show that these estuaries are flood dominant estuaries.

Storm-induced flooding and other damage present a major problem as the coastal population continues to increase rapidly and sea level keeps rising. To predict the path and landfall of a hurricane or other coastal storm and assess the damage, emergency managers and scientists need continuous information on the storm's path, strength, predicted landfall, and expected damage over large areas. Satellite and airborne remote sensors can provide the required information in a timely and reliable way, as demonstrated by a case study of hurricane Katrina's impact on New Orleans and surrounding areas. Satellite images and hurricane hunter planes were used to track hurricane Katrina, with modelers predicting accurately its path, strength, surge level, and landfall location. Shore-based radars were used to confirm the data as the hurricane approached land. Medium- and high-resolution satellite sensors, helicopters, and aircraft were employed to assess damage to the city, including transportation, power, and communication infrastructures, and to adjacent wetlands and other coastal ecosystems. The lessons learned from hurricane Katrina are helping to optimize future approaches for tracking hurricanes and predicting their impact on coastal ecosystems and developed areas.

Three Tunisian lagoon and coast locations, diversely subjected to human activities and differing according to their degree of communication with the sea, were studied seasonally. Main environmental parameters and the trophic structure and biodiversity parameters of the benthic macrofauna were determined and analysed. Results show that the sites are quite different and each one has its own seasonal fluctuation linked certainly to environmental and anthropogenic factors. In the almost-enclosed lagoon of Ghar El-Melh with high salinity, selective deposit feeders dominate in spring and summer, and in the other seasons the trophic structure is rather balanced. In the southern lagoon of Tunis where environmental factors are more fluctuating and man-made activities of Tunis City and its suburbs are more important, the community is clearly more enriched because of the strong dominance of leader species. In this site, micrograzers dominate clearly all year, with a slight increase in winter. However, in the Bay of Tunis, which is a coastal area more open to the sea, the community is clearly less enriched and no dominance of the leader species was noted. In this site, the trophic structure seems to be clearly more balanced since most trophic groups are almost equally represented.

The distributions of a variety of variables were used to characterise the physicochemical structure of inner bay waters in a reefal bay with a central channel. The aim was to describe emanations of the bay waters and the effectiveness of particular variables in depicting these emanations. In Wreck Bay—a semienclosed reefal bay located along the Hellshire south-east coast of Jamaica—distribution in temperature, salinity, dissolved oxygen, pH, and specific conductivity were used as potential indicators of the inner bay waters and their emanations. Variable profiles and contours showed that salinity and specific conductivity were found to be unreliable in characterising the bay waters because of the interruptions from numerous submarine seeps found inside and outside of the bay. However, temperature, pH, and dissolved oxygen were more robust in characterising bay waters with continuity from the inner bay, past the reef, and out to sea, even with the presence of the seeps. Surface emanations of bay waters beyond the reef were pronounced with the land-breeze regime but retarded by the entrainment of the sea breeze. Using these variables, it was evident that the reef was not effective in cutting off bay water and that inner bay waters and their characteristics persisted beyond the reef.

Salt marshes form part of the widely distributed intertidal landscape. The salt marshes of the East Frisian barrier island Langeoog (NW Germany) belong to the barrier-connected salt marsh type and were protected by a summer dike that was removed in 2004. In this study, pore water and sediment data were combined to investigate the effects of the de-embankment along a transect including sites on seawater-influenced grassland, high and low salt marsh, and transition zone tidal flat–low salt marsh. Pore waters were sampled with in situ pore water samplers for 13 mo and analysed for trace metals (Fe, Mn), nutrients (NH₄ , PO₄³⁻), dissolved organic carbon, and sulphate. Additionally, on site measurements of pH and salinity were carried out. Pore water ultrafiltration experiments with 5000 Da MWCO (molecular weight cut off) complemented the water analyses. Sediment samples were taken from hammer corings and were analysed for bulk parameters (total carbon [TC], total inorganic carbon [TIC], total organic carbon [TOC], total sulphur [TS]) and selected major elements (Si, Al, Fe, Mn). Additionally, reactive iron and manganese were analysed.

Sediments along the study transect are characterised by quartz dominance and very low TC (TOC and TIC) and TS contents. The iron content is comparable to other salt marsh sediments. The high percentage of reactive iron (up to 40%) indicates that salt marsh sediments form an important iron source for pore waters, as confirmed by high pore water concentrations of dissolved iron (up to 583 μM). Dissolved iron in pore waters most likely results from reduction and dissolution of oxidised iron minerals by organic ligands or Fe(II) organic complexes. Iron complexation by humic substances and siderophores in combination with circum-neutral pH values keep iron in solution. Therefore, the studied salt marshes presumably form an important iron reservoir, which may account for elevated pyrite contents frequently observed in Holocene coastal peats.

Flooding of the salt marsh during a storm surge resulted in a considerable increase in pore water iron (8-fold), manganese (21-fold), phosphate (5-fold), and ammonia (7-fold) concentrations. These results show that seawater restoration (de-embankment) should be handled very carefully, especially with regard to nutrient release and subsequent changes in pore water quality.

Here we present shoreline change rates for the beaches of southeast Oahu, Hawaii, calculated using recently developed polynomial methods to assist coastal managers in planning for erosion hazards and to provide an example for interpreting results from these new rate calculation methods. The polynomial methods use data from all transects (shoreline measurement locations) on a beach to calculate a rate at any one location along the beach. These methods utilize a polynomial to model alongshore variation in the rates. Models that are linear in time best characterize the trend of the entire time series of historical shorelines. Models that include acceleration (both increasing and decreasing) in their rates provide additional information about shoreline trends and indicate how rates vary with time. The ability to detect accelerating shoreline change is an important advance because beaches may not erode or accrete in a constant (linear) manner. Because they use all the data from a beach, polynomial models calculate rates with reduced uncertainty compared with the previously used single-transect method. An information criterion, a type of model optimization equation, identifies the best shoreline change model for a beach. Polynomial models that use eigenvectors as their basis functions are most often identified as the best shoreline change models.

The present work is an observational analysis of the small-scale variations induced by Chesapeake Bay outflow on coastal surface circulation off Virginia. The variation in freshwater discharge into Chesapeake Bay is investigated as a triggering mechanism for local coastal jets. While it is known that an extra amount of freshwater received from the tributaries will lead to an increased total outflow, the effect on the outflow surface signature (the upper meter) has not been extensively explored.

Our analysis is based on surface currents, wind data, and freshwater discharge records. The surface currents were derived from two high-frequency Doppler radars deployed on the Virginia coast during September and October 1996 and 1997. The wind data were obtained from a nearby weather Coastal-Marine Automated Network station, and the freshwater discharge data were from the U.S. Geological Survey stations located at the mouth of each tributary. The freshwater discharge into the bay observed during 1996 decreased from 4200 to 1000 m³/s in 10 days, while for the 1997 period it varied between 500 and 5500 m³/s in 1 week.

The present analysis shows that sudden variations of freshwater flux will drive the plume further offshore before its normal southward turning, in the same way upwelling-favorable winds do as reported in all the available literature of the area. Strong freshwater variations on weekly scales are then shown to be an important factor in determining the extent of the surface plume displacement and the fate of the shelf currents or jets.