Cabo Falso is located on the southern coast of the Baja California peninsula. The beach is broad and wide with a steep face and tall foredunes on the backshore. Landwards, an active, predominantly parabolic dune field has developed with average heights of 30 m. Part of the field is used by recreational all-terrain vehicles. The main goal of this study was to identify the principal morphodynamic characteristics of the deposits influenced by these recreational activities and affected by Hurricane Juliette in 2001. The morphology of the study area was monitored using seasonal topographic profiles, examination of aerial photographs from 1972 and 1993, and on-site photographs (November 1999 to April 2002). The topographic profiles indicated that the erosion period for both the beach and the dunes was June to December. Hurricane Juliette was the responsible for most of the observed erosion. The greatest sediment accumulation occurred between December 2001 and February 2002, associated with the onset of the natural recovery process of the beach–dune system. The photographs revealed that the dunes have lost vegetation cover because of the activities of all-terrain vehicles, which erode paths perpendicular to the dune crests. This in turn allows increased sediment movement, resulting in instability of the dune field system.

Although the dynamics and kinematics of various types of mean cross-shore current flows in the surf zone (undertow and rip currents) are fairly well understood, the causes for transitions occurring between these two types of mean circulation patterns remain obscure. On longshore barred beaches, such transitions involve the formation, degeneration, or both of rip channels. In this paper, field evidence is presented to suggest that transitions between undertow and rip current (cell) circulations could depend on the magnitude of the wave-induced onshore mass transport across a longshore bar, rip channel spacing, and trough cross-sectional area. The results are based on data obtained from four field experiments on the Danish and Dutch North Sea coasts, which encompassed a range of incident wave energy conditions. Two of the data sets demonstrate transitions between cell and undertow circulations. Calculated onshore-directed mass transports in the two circulation types were plotted against A_t/y_r, where A_t is trough cross-sectional area and y_r is longshore distance from the measurement position to a rip channel. The two types of circulation are separated in parameter space by a straight line with a slope of 1 (m/s). The observations support a model proposed previously, in which optimum rip spacings exist that depend on the balance between onshore discharge and longshore pressure gradients caused by irregular bar bathymetry. This simple morphodynamic model indicates that both hydrodynamic conditions and existing bathymetry are critical in determining the type of mean current circulation.

California beaches depend on rivers for the majority of their sand supply, but coastal dams, which prevent sand from getting to beaches and nourishing them naturally, have significantly reduced this supply. Cumulative sand impoundment volumes for each littoral cell provide insight into which littoral cells have been impacted by human activities and where there may be a potential need to augment the littoral budget. Suspended sediment rating curves were created for the 21 major coastal streams in the state to estimate present-day sand fluxes based on relationships between suspended load and bed load. We then compared the postdam sand fluxes to estimated sand fluxes under predam conditions to determine the effects that dams have had on fluvial sand delivery to the coast. The cumulative sand impounded by California's 66 major coastal dams was then calculated on a littoral cell basis.

Under predam conditions, California rivers delivered an average of about 10,000,000 m³/y of sand to the coast, but this flux has been reduced by about 2,300,000 m³/y due to dams. The reductions vary regionally: in northern California, the predam annual sand flux has been reduced by about 5%; in central California, the predam annual sand flux has been reduced by about 31%; and in southern California, the predam annual sand flux has been reduced by about 50%. Cumulatively, about 152,000,000 m³ of sand has been trapped by all of California's coastal dams since 1885.

In the context of the REVIZEE programme, an extensive sampling cruise was carried out in the northern section of the Brazilian Exclusive Economic Zone on board O.V. Antares (Operation North III). Several parameters were surveyed along the Amazon continental shelf during this cruise, such as horizontal and vertical distributions of temperature, salinity, dissolved oxygen, pH, dissolved inorganic nutrients, and phytoplankton biomass. Water with salinity below 33 psu and high silicate content was observed throughout the shelf, indicating the influence of the Amazon River plume up to a distance of 147 km from the coast; pH always remained alkaline. Water temperature was relatively homogeneous at the surface, with an average of 28°C. A permanent thermocline was detected in oceanic regions. Coastal waters were eutrophic, well oxygenated (maximum of 6.54 mL O₂ L⁻¹), and presented high chlorophyll a (maximum of 9.8 mg chlorophyll a m⁻³) and nutrient concentrations (up to 9.54 μmol L⁻¹ NO₃⁻, 0.89 μmol L⁻¹ PO₄²⁻, and 108.59 μmol L⁻¹ Si0₄⁴⁻). Oceanic waters adjacent to the Amazon shelf presented high transparency (Secchi depth up to 35 m) and chlorophyll a (mean: 0.1 mg m⁻³) and low nutrient concentrations (maximum of 1.58 μmol L⁻¹ NO₃⁻, 0.18 μmol L⁻¹ PO₄²⁻, and 5.92 μmol L⁻¹ Si0₄⁴⁻). Cluster analysis performed with all data showed a clear separation between coastal and oceanic waters at the surface layer and at 1% light penetration layers. This separation into two groups of stations clearly represents areas with different degrees of influence from the discharges of the Amazon Basin. The Amazon River is very important to the nutrient budgets of the shelf.

A 5-year artificial-tracer study was used to mimic bioturbation of foraminifera in the back-barrier marshes of Folly and Rat Islands, South Carolina. Mixing rates decrease with subenvironment elevation, and decadal- to centennial-scale ecological signals and smaller hurricane deposits would not survive passage through the low-marsh mixing zone. However, the lower mixing rates in the high-marsh subenvironment allows for the preservation of such signals in the stratigraphic record. Bioturbation rates correlate poorly with plant density (primarily Spartina alterniflora). The Pearson correlation coefficient between mixing rate (I_m in centimeters) and halophyte density (stems per square meter) is only 0.46, while the correlation between mixing and burrow density (apertures per square meter) is a much stronger 0.83. This corroborates earlier reports that spatiolateral variability in bioturbation is primarily a result of bioturbator (Uca spp.) preference for the low marsh and not halophyte distribution.

Two factors contribute to the preservation of storm layers in the marshes behind Folly Island: (1) Hurricane deposits are laterally continuous and deposited across both low and high marsh, and (2) the coarser grain size of the washover sediments and the thickness of the larger storm deposits inhibit crab burrowing. Although the extensive paleostorm record from Folly Island appears to show a decrease in category 4 and 5 hurricanes through time, this record may reflect change in marsh paleosubenvironment. In a transgressive setting, where a formerly high marsh is submerged into low marsh, the preservation potential of storm deposits decreases through time.

A cyclone known as Gudrun in the Nordic countries developed above the North Atlantic and traveled over the British Isles, Scandinavia, and Finland on January 7–9, 2005. As a result of high initial levels of the Baltic Sea, the fast-traveling cyclone with a favorable trajectory and strong SW–W winds created a record high storm surge (275 cm) in Pärnu, as well as in many other locations along the west Estonian coast. The January storm induced clearly visible changes in the development of shores and the dynamics of beach sediments over almost all of Estonia. The precondition for the profound changes observed from this storm—which has been observed in connection with some previous major storms—was a combination of the absence of protecting ice cover in the sea, relatively high sea level for a long period before the storm, and a very intensive storm surge taking place over the background of the already elevated sea level. Strong storm waves combined with the high sea level caused substantial changes in the coastal geomorphology of depositional shores on Saaremaa Island, Estonia. The most exceptional changes occurred in the areas that were well exposed to the storm winds and wave activity—for instance, in Kelba, where the high rate of erosion (<3000 m³) resulted in the elongation of a spit by 75 m. Our conclusion is that the January 2005 storm caused significantly larger changes to the depositional shores in west Estonia than the cumulative effects of ordinary storms over the preceding 10–15-year period.

A simple and robust suspended load transport formula for noncohesive sediment is presented for application to river, estuarine, and coastal environments with the use of depth-averaged models. The formula is based on an exponential profile for the concentration and assumes a constant velocity over depth to simplify the calculations. These assumptions were validated with a large data set, including data with a steady current, wave and current interaction, and breaking waves. The formula has two parameters: the mean sediment diffusivity over depth and the bottom reference concentration. The sediment diffusivity is estimated assuming a linear combination of mixing because of breaking waves and the energy dissipation in the bottom boundary layer from the mean current, waves, or both. The bottom reference concentration is a function of the Shields parameter. Overall, the formula developed in this study yields the best agreement with the compiled data set compared with a number of existing formulas for estimating the suspended load.

A three-dimensional Princeton Ocean Model has been configured for the east coast of India to study the circulation and coastal upwelling during the pre-monsoon season of 2000. The model uses an orthogonal curvilinear grid and a terrain-following sigma coordinate in the vertical with monthly data fields of temperature and salinity from “Levitus94.” The model is applied to study the coastal ocean processes and its variability on weekly timescales off the east coast of India. The forcing in the model is the real-time weekly averaged wind stress obtained from Quik Scattero-meter/National Center for Environmental Prediction blended wind of May 2000.

The discernable variability in the winds of May 2000 over the weekly timescale influenced the surface layers reflected in the 3-day mean satellite images. To simulate this feature and to understand the dynamics, numerical experiments are carried out with the associated real-time winds. Both diagnostic and prognostic computations are used for this, and the model simulations off Paradip and Visakhapatnam are examined to study the variability of the processes on weekly timescales. he model-simulated sea surface temperatures in different experiments are in qualitative agreement with the available 3-day mean Tropical Rainfall Measuring Mission Microwave Imager satellite images.

Apart from simulating the typical characteristic features, the model also could simulate the observed intense coastal current leaving the coast to form an eastward jet in the pre-monsoon season. The associated anomalous weaker circulation in the head bay can be attributed to the built-in opposing density currents developed in that region. The simulations suggest that the head bay is delineated from the rest of the bay in terms of its physical properties as well as physical processes.

The optically stimulated luminescence (OSL) dating method was used to determine the geochronology of seven relict beach ridges that sit immediately behind the modern beach at Beachmere, a low-energy sandy coast within Moreton Bay, Queensland. Between 2600 ± 400 and 1700 ± 130 years ago, the shoreline eroded and foreshore sediment was deposited over the older beach deposit. Subsequently, there was a 1500-year period of shoreline progradation: the shoreline advanced 0.16 m/y between 1700 ± 130 and 1140 ± 80 years ago; and 0.41 m/y between 1140 ± 80 and around 200 years ago. Shortly after 690 ± 60 years ago, a series of well-developed regularly spaced beach ridges gave way to an intertidal flat and then deposition of a set of lower amplitude, closely spaced beach ridges. The younger ridges were deposited between 230 ± 40 and 140 ± 50 years ago, at a rate of around 1.06 m/y. During the last several decades, much of the Beachmere shoreline has eroded into these younger relict ridges. Drivers of these changes in shoreline sedimentary regime are yet to be accurately determined; however, it seems likely they are related to switches that occur in the nearshore sand transport pathway. Our results demonstrate the utility of the OSL method for providing insights into coastal change that occurred in the historical and recent geological period. Better understanding the tempo of shoreline change in the recent past is particularly relevant for assessments of vulnerability to erosion of rapidly developing, low-lying sandy coasts such as northern Moreton Bay.

The effects of stochastic events on estuarine water quality parameters are often difficult to quantify spatially due to the inherent variability in these systems. The use of geographic information systems to identify spatial patterns and trends can improve such efforts. This work describes the use of geographic information systems and the Mantel Test to determine the existence of trends and the persistence of spatial patterns in the relationships between nutrients and chlorophyll a in an urbanized lagoonal estuarine system, Murrells Inlet, South Carolina. Relatively dry and wet periods were compared, the latter following several substantial precipitation events related to tropical hurricane activity in the summer of 1999. Dissolved inorganic nitrogen concentrations were elevated following the passage of Hurricane Irene, and chlorophyll a did not increase concomitantly. Orthophosphate was found to have persistently higher concentrations in the more urbanized regions of Murrells Inlet that were consistent spatially during the two sampling periods. Strong spatial and temporal correlations between chlorophyll a and dissolved silicate : dissolved inorganic nitrogen suggest a relationship between the latter ratio and the phytoplankton growth. However, there appeared to be only a tenuous relationship between chlorophyll a and dissolved inorganic nitrogen and phosphorus, both spatially and temporally, suggesting that nutrient requirements for phytoplankton growth were met by internal estuarine processes, during this time period.

Land use changes have been shown to alter the balance of nutrient and mineral sources and sinks to coastal systems. These shifts are often preserved in sediment records. In Apalachicola Bay, productivity is dependent on nutrient loading from the Apalachicola-Chattahoochee-Flint (ACF) river basin; alterations to ACF watershed flow by management activities coupled with increased marine water inundation associated with rising sea level threaten this productivity. The objective of this research was to evaluate past changes in nutrient loading to Apalachicola Bay as recorded in sediment history and determine if these changes could be associated with both anthropogenic and natural alterations in the system. Sediment cores from three sites in the bay were collected and analyzed for organic carbon (C), total nitrogen (N), and total phosphorus (P) concentrations and δ¹³C and δ¹⁵N stable isotopic abundances. The three sites are located at the river mouth (S1), mid-bay (S2), and in the northeastern region of the bay (S3). Carbon and nitrogen concentrations, ratios, and stable isotopes coupled with grain-size shifts for the bay suggest a decrease in river organic matter supply and a change in sediment clay content supply and/or distribution for the bay. Overall, the applied indicators suggest an increase in marine influence on the organic matter in the estuary. These shifts appear to be associated with Apalachicola River management practices coupled with sea-level rise in the Gulf of Mexico.

Konkan is the coastal lowland extending east–west from the Arabian Sea to the Western Ghat escarpment and north–south from north of Mumbai to north of Goa. The city Malvan is located in Sindhudurg district and bounded by three creeks viz., Karli, Kolamb, and Kalavli, of which Karli and Kalavli are the major rivers giving sediment input for this coast. The place is well known for the Sindhudurg Island Fort built by the Maratha King Shivaji during the 16th century and is crowded by tourists during the fair-weather season. The present study is a preliminary work and emerged while carrying out remote sensing application on the southern coast of Maharashtra. Hence, the present report does not have detailed in situ/field data. The remote sensing data provide significant information regarding physical setting, tectonic features, and coastal landforms, especially the large-scale morphological features such as beach ridges, spits, bars, islands, barrier beaches, and lagoons. In the present study, beach ridges and lineaments were observed along the Malvan coast and have been utilized to understand the evolution of the Malvan coast. Along with this, coastal erosion/accretion and landform/land cover classification have also been undertaken using remote sensing data.

The applicability of grain-size trend analysis for determining sediment transport pathways was investigated on two macrotidal shorefaces of the southern North Sea and Dover Strait where sediment transport is strongly controlled by well-defined, shore-parallel, tidal currents. Sediment transport directions were defined following the Gao and Collins (Sedimentary Geology, 80, 47–60) method, using surficial sediment samples collected from 0 to 8 m water depths. Grain-size trend analysis produced results in relatively good agreement with the directions of near-bottom currents measured in the vicinity of the sampling sites in some cases, but also yielded more confused patterns of calculated transport vectors in others. The best results were obtained when using discrete sets of samples collected during a distinct half tide–cycle. Comparison of threshold shear velocity for sediment motion with estimates of bed shear velocity obtained from near-bottom current data recorded simultaneously with sediment sampling indicates that sediment transport was most likely occurring when sediment samples were collected, suggesting that the grain-size trends observed in the surface sediments probably reflect the last transport event. Our results suggest that grain-size trend analysis can be efficient for determining the mean transport direction of the last sediment transport event when applied to small areas and when sampling is limited to the thickness of the active layer of sediment remobilisation. This method may be appropriate, however, for defining time-averaged residual transport directions when applied to larger areas over which progressive variations in surface sediment distribution reflect a longer term adjustment to hydraulic regime.

Studies of benthic communities in tropical shelf waters are limited. In this study, we deal with the infaunal benthic community of soft bottom sediment of the tropical eastern Arabian Sea shelf. Benthic macroinfauna was sampled with a Smith–McIntyre grab at 30 stations on the continental shelf of the eastern Arabian Sea (northwest coast of India) during January–February (premonsoon) and November (postmonsoon) 2003 from 30 to 200 m depth. The faunal composition, abundance, and diversity of species together with environmental parameters are reported. The sites were clustered into “associations” on the basis mainly of sediment texture and depth. Mean benthic abundance was high in the shallow and intermediate depths and decreased toward deeper areas. Diversity increased with depths up to 100 m during both seasons and decreased beyond 100 m depth. The dominant benthic group was Polychaeta during both seasons. Species richness and diversity were higher during premonsoon compared with postmonsoon. Shallow depths were dominated by deposit-feeding polychaetes, and deeper depths were dominated by deposit and filter feeders such as crustaceans and molluscs. Diversity was high in the medium grain–sized sediment. In the sandy environment, a mollusc–Littorina–Cresis community that dominated during the premonsoon period changed to a Tellina–Mactra community during the postmonsoon period. In the fine sediment, in which the fauna was dominated by deposit feeders such as Prionospio pinnata, no obvious change in the community was observed during the two seasons. From this study, we deduced that the variations in the macrobenthic community were mainly controlled by sediment texture, depth, and dissolved oxygen.

Most migrant shorebirds require coastal and estuarine habitat in the nonbreeding season and their overwinter survival is contingent upon the composition and quality of these winter sites. The purpose of this study was to investigate the relationship between the distribution and abundance of the piping plover, a federally threatened and endangered shorebird, and its nonbreeding habitat along the Gulf of Mexico coastline. We identified sites consistently used by wintering piping plovers and quantified landscape and anthropogenic features within a subset of those locations. Using published literature, we documented that piping plovers consistently winter at 49 locations on the U.S. Gulf of Mexico coast (Marco Island, Florida to Padre Island, Texas). At 31 sites, we conducted a remote analysis of aerial photos for 11 features (e.g., intertidal area, urban area, beach). Linear regression was used to test correlations between plover abundance and landscape characteristics. We found that certain shoreline features (e.g., landform, intertidal area, total area) and measures of urbanization (e.g., urban area, length of roads) were significantly correlated, positively and negatively, respectively, with piping plover abundance across the Gulf of Mexico coastline. This information is critical to prevent or mitigate negative impacts of urbanization and subsequent coastal landscape change on shorebird populations.

The main purpose of this study is to estimate daily mean sea level heights using five different methods, namely the least squares estimation of sea level model, the multilinear regression (MLR) model, and three artificial neural network (ANN) algorithms. Feed forward back propagation (FFBP), radial basis function (RBF), and generalized regression neural network (GRNN) algorithms were used as ANN algorithms. Each method was applied to a data set to investigate the best method for the estimation of daily mean sea level. The measurements from a single tide gauge at Newlyn, obtained between January 1991 and December 2005, were used in the study. Daily mean sea level estimation was carried out considering the precedent 8-day mean sea level data of the same station, the average and standard deviation of each day for a 15-year period, and 6 monthly and yearly periodicities in tidal variations. Results of the study illustrated that the ANN and MLR models provided comparatively better results than the conventional model used for estimating sea level, least squares estimation. FFBP, RBF, and MLR algorithms produced significantly better results than the GRNN method, and the best performance was obtained using the FFBP algorithm. From the graphs and statistics, it is apparent that neural networks and MLR solution can provide reliable results for estimating daily mean sea level.

At 20 UK beaches, 1844 respondents were interviewed, 421 on the southern shore of the Bristol Channel, England, 660 in north and middle Wales, and 763 in south Wales. The modal group was female aged 30–39, whilst professionals, retired people, and housewives were the main socioeconomic groupings. The research goal was to determine: how important the beach was to the user, the state of the beach with respect to litter aspects, and the offensiveness of various beach pollution types. The modal response to beach importance was that the beach was “very important” for holidays. Respondents generally perceived the beach grade to be in line with the actual beach litter grade assigned according to an official litter protocol. The exception was for results obtained from the southern shore of the Bristol Channel, where frequent occurrences of cotton buds (Q-tips) were often ignored by the public as being representative of a sewage transport system. At every beach, sewage-related debris (SRD) was rated as the most offensive pollution type followed by oil on both water and beach.

The present study attempts to delineate the late Quaternary morphotectonic evolution of the coastal zone of Kachchh on the basis of detailed field mapping of the various coastal and fluvial landforms and lithostratigraphic studies of the associated sediments. The entire coastline has been divided into five morphologically distinct segments from west to east—Narayan Sarovar–Jakhau, Jakhau–Khuada, Khuada–Bhada, Bhada–Mundra, and Mundra–Surajbari segments. Major geomorphic features of interest are the variable width of the intertidal zone; development of beaches, bars, and spits; width of active and stabilised coastal dunes; raised mudflats; raised beaches; uplifted estuarine tidal terraces; and the development of a coastal alluvial plain in the Jakhau–Khuada and Bhada–Mundra segments. The coastal alluvial plain was formed by deposition of fluvial sediments over the peneplained Tertiary rocks during upper late Pleistocene in two separate tectonically created basins. Deeply incised fluvial valleys were formed in response to tectonic uplift of the coast due to movements along E-W trending faults further north during the early Holocene. The sea level was higher than present during 6–2 ka, which led to the deposition of coastal sediments, fluvial terraces along incised fluvial valleys, and formation of a cliffy coast in the Narayan–Sarovar–Jakhau segment. Emergent coastal features consisting of raised beaches, raised mudflats, abandoned coastal cliffs, uplifted estuarine tidal to fluvial terraces, and stabilised coastal dunes developed because of uplift during the last 2 ka. The various morphotectonic divisions of the coast are attributed to the role played by the inherent structural fabric, the subsurface Median high, and general uplift of the coast due to tectonic activity along the E-W trending faults to the north of the study area during the early Holocene and the last 2 ka.

Eighty-Mile Beach is one of the 10 most populous sites for migratory birds in the Asian–Australasian Flyway. The birds come to Eighty-Mile Beach's tidal mudflats to feed on benthic organisms during their nonbreeding period prior to embarking on a 10,000–15,000-km migration to their breeding grounds in the Arctic. To better understand migratory birds' preferences for areas on the beach, satellite imagery was used to predict grain size and benthic invertebrate distributions. These data were statistically compared with data collected in the field to determine the accuracy of the predictions. Relationships were apparent between compared data, especially in respect to the actual benthic invertebrate distribution. Finally, feeding areas for different bird species were mapped according to where their favored foods would be found. Knowing where the birds should be feeding will help prioritize research and conservation efforts on Eighty-Mile Beach.

Because of the myriad of environmental concerns related to critically eroded shoreline areas, recycled glass (cullet) has been postulated as a potential alternative source material for beach fill. However, the newly proposed cullet beach material must uphold the nesting incubation properties of endangered species such as sea turtles. This study is the first in which the abiotic parameters of recycled glass cullet is investigated as an alternative beach fill material in relation to the nesting habitat requirements of marine turtles. By constructing a simulated sea turtle nesting hatchery and with the use of thermal/moisture logging sensors and extracted gas probe samples, we determined that recycled cullet maintains the abiotic nesting chamber properties to allow for successful sea turtle embryo development. Simulated nests containing recycled glass cullet recorded average temperatures (27.0–31.4°C) that fell within the acceptable incubation range for sea turtles and moisture content readings that showed no significant differences from the beach sand controls (p > 0.05). Similarly, gas probe samples analyzed from all the experimental cullet nests recorded high concentrations of oxygen (≥20.0%) with no significant variations from the beach sand controls (p > 0.05). Overall, this study showed that nests constructed with a portion of recycled glass cullet offered a nesting environment equal to the developmental conditions of the native beach sand. Worldwide, the nesting beaches of sea turtles are under the constant threat of erosion, which ultimately results in the loss of nesting habitat. With this research, we document that recycled glass cullet can provide a sea turtle–friendly alternative for beach protection.

The vast majority of boundaries within the littoral zone are based on one of the many possible tidal lines. These tidal lines are defined by the line of intersection between a particular tidal datum and the land mass. The difficulty with boundaries defined on the basis of a tidal datum is that the rigorous and consistent realisation of the line of intersection between a nominated tidal datum and the land mass is notoriously difficult, creating spatial uncertainty and the potential for conflict and dispute.

This paper describes and discusses some fundamental issues in defining and realising tidal lines, with particular interest in their relevance and application to the development of a marine cadastre. A technical solution for realising the line of intersection between any given tidal datum and the foreshore terrain is presented. Particular attention is paid to the modelling of the water and terrain surfaces as the two fundamental datasets required for the intersection computations. The methodology and results of a case study in New South Wales, Australia, are presented, along with some initial findings.

Several studies have demonstrated that areas of seagrass show significantly greater density, richness, and diversity of fauna than adjacent unvegetated areas. Most investigations have dealt with midsized and larger seagrass species that usually form dense, highly structured meadows. Similar studies of smaller seagrasses have rarely been carried out. The objective of this study was to investigate whether the small, low biomass Halophila decipiens Ostenfeld confirms the paradigm observed in larger seagrass species by showing a greater macrofaunal density and diversity than adjacent bare, soft-bottom areas. Plant mean biomass at Urca inlet was 1.83 g m⁻². Crustacea were the most abundant, frequent, and constant group in both habitats. Six taxa were significantly more abundant in the vegetated habitat, while only one taxon was enhanced in the habitat without H. decipiens. Total mean density, richness, and diversity of macrofauna were significantly higher in vegetated areas. Habitat complexity, higher productivity, or both associated with the seagrass were responsible for the differences found. Our results confirm and reinforce the paradigm that seagrass habitats have a greater density and diversity of macrofauna than adjacent unvegetated areas. However, adjacent unvegetated areas can present different sets of species that, even though less diverse, contribute to enhance local diversity.

A selected record of the measured wind wave data, which contained the maximum wave height during a mistral event, was divided into five segments, and computations of wavelet bicoherence were conducted for the whole record and for all divided segments in order to analyze the details of nonlinear wave-wave interactions.

In computing wavelet bicoherence, both sum and difference rules of frequencies were considered. A close inspection of the computed wavelet bicoherence for the whole record of wave height and the divided segments reveals that the details of wave-wave interactions are better explored by considering five-minute segments of wave height. Averaging over the whole record of wave height causes loss of important temporal characteristics in nonlinear wave-wave interactions.

Hydrological coupling between watersheds and estuaries is an important element in establishing eutrophic conditions in coastal waters. In coupled systems, nutrients derived on land enter estuaries through groundwater flow or stream runoff, resulting in increased rates of primary production. The extent of coupling is determined by precipitation, evapotransporation, and water use practices. We use stable nitrogen isotopes, salinity, and nutrient data to assess coupling in two temperate and two tropical ecosystems. In each region, we selected two estuaries, one pristine and one with considerable agricultural or urban development. In pristine systems freshwater entering estuaries had low nitrogen concentrations and low nitrogen isotopic signatures. In receiving waters of the pristine systems, there were similarly low nutrient concentrations, and the isotopic signatures in the estuary were similar to the signatures of incoming groundwater. In both disturbed sites freshwater on the watershed had high nitrogen concentrations and enriched nitrogen isotopic signatures. In the temperate system, the estuarine water had high nitrate concentrations and nitrogen isotopic signatures that were similar to that of the incoming freshwater, indicating that the watershed and estuary were tightly coupled. In contrast, in the disturbed tropical site the estuary had extremely low nitrogen concentrations, and the isotopic signatures were unrelated to the signatures found in freshwater on the adjoining watershed. These results demonstrate that under sufficiently dry conditions, watersheds and estuaries may be uncoupled.