Geologic and geomorphic data on 42 world deltas were compiled for a NASA-sponsored research project. Satellite images from 14 of these deltas (Danube, Ganges, Brahmaputra, Indus, Mahanadi, Mangoky, McKenzie, Mississippi, Niger, Nile, Shatt el Arab, Volga, Huang He [Yellow], Yukon, and Zambezi) were analyzed for delta plain wetland loss caused by natural causes and conversion of wetlands for agricultural and industrial use. These analyses indicated that a total of 15,845 km² of wetlands have been irreversibly lost during the past 14 years and the average rate of loss is 95 km²/y. If a similar trend is present in the other deltas, a total wetland loss in the delta plains of the 42 deltas would be on the order 364,000 km² over the past 15 to 20 years.

A multidisciplinary approach was taken to assess the potential importance of groundwater seepage to nutrient inputs into Manila Bay, Philippines. Three lines of seepage meters were installed in transects along the coast at Mariveles, Bataan Province, during the period 8–10 January 2005. The overall average seepage flux was 5.1 ± 5.4 cm d⁻¹ (n = 73) with a range of 0–26 cm d⁻¹ and a calculated integrated shoreline flux of 12.4 m³ m⁻¹ d⁻¹. Additional methodologies employed included automatic seepage meters, resistivity measurements, sampling for nutrient analyses in both seepage meters and ambient seawater, and use of natural radon as a groundwater tracer. Seepage meter and tracer results provided consistent results of estimates of submarine groundwater discharge into Manila Bay. Many lines of evidence suggest that seepage fluxes are not steady state but are modulated by the tides. Resistivity profiles show that the saline-freshwater interface moves on a tidal timescale, consistent with the observed drop in salinity of the seepage waters as low tide approaches. Our results show that dissolved inorganic nitrogen (DIN) fluxes via submarine groundwater discharge are comparable in magnitude to DIN fluxes from each of the two major rivers that drain into Manila Bay.

The determination of the amount and size distribution of carbonate and noncarbonate materials in a given sediment sample is significant to coastal engineers and geologists. Typically, laboratory procedures physically remove the carbonate portion of the sample from the entire sample, so that the amount and distribution of noncarbonate material remaining can be established. Rather than performing such a procedure, the authors have proposed a Bayesian Carbonate Determination (BCD) technique, which can be used to calculate the percentage of carbonate material in a bimodally distributed sediment sample from data obtained through an initial sieve analysis.

The BCD technique is based on the assumption that the combined probability density function is bimodal and that the carbonate and noncarbonate portions of the sample follow independent distributions. The BCD technique employs the grain-size probability distribution to determine the threshold point that separates the two sample portions with minimum error. For samples with bimodal sediment distributions, the errors associated with use of the BCD technique have been found to be less than the standard deviation between the samples.

The present study extends the original investigation that introduced the BCD technique. This article identifies the limitations of the BCD procedure and introduces a more general Carbonate Determination Filter (CDF) procedure for determination of the percentage of carbonate within a specific size range for a given sample.

The well-known and enormously controversial Three Gorges Reservoir (TGR) on the Yangtze River, China, impounded about 9.936 × 10⁹ m³ of water (between Qingxichang and Huanglingmiaodou) for the first time from May 25 to June 10, 2003, finally elevating the water level to about 135 m above mean sea level at the dam. Mainly on the basis of daily, monthly, and annual water and sediment data sets of the Yangtze River at mainstream hydrological stations above and below the TGR Dam in 2003, we preliminarily examined the effects made by the TGR water impoundment in June 2003 on the Yangtze River sediment. According to sediment transport balance method, the estimated amount of suspended sediment impounded in the TGR is (1) about 3.1816 × 10⁶ t between Qingxichang and Huanglingmiaodou during June 1 to June 10; (2) about 1.247 × 10⁸ t between Cuntan and Yichang in 2003, which in June accounted for 25.9% and from June to December accounted for 99.2%; and (3) about 1.359 × 10⁸ t between Cuntan and Yichang in 2003, if considering eroded sediment from the channel between the TGR Dam and Yichang. The TGR sedimentation resulting from the TGR water impoundment leads to unnaturally clear water discharged from the TGR Dam, which results in the Yangtze River suspended sediment concentration and sediment load downstream of the TGR Dam in 2003 being reduced more than those above the TGR Dam, and the channel just below the TGR Dam significantly eroded (about 4.759 × 10⁵ t between Yichang and Shashi from June 1 to June 10).

A finite element wave propagation model for linear periodic waves in a coastal sea region is developed. The model includes refraction, diffraction, and reflection of gravity waves on water over arbitrary bathymetry. The authors discuss the use of the computer model in simulating waves using a number of classical examples involving a circular pile, submerged shoal, and breakwater. The method of solution involves complex potential theory. The equation used by Berkhoff (1976; Mathematical Models for Simple Harmonic Linear Water Waves—Wave Diffraction and Refraction. Delft: Delft Hydraulics Laboratory, Delft University of Technology, p. 111) and the authors within the domain is elliptic in type allowing wave trains to cross, thereby producing amphidromic points. An amphidromic point is the two-dimensional version of a node in a one-dimensional standing wave caused by imperfect reflection or wave train interference. Radiating and partially reflecting boundaries are modelled by the authors, using a parabolic equation developed in different ways by Radder (1979; On the parabolic equation method for water-wave propagation, Journal of Fluid Mechanics, 95, 159–176) and Booij (1981; Gravity waves on water with non-uniform depth and current. Delft: Delft Hydraulics Laboratory, Delft University of Technology, p. 127), allowing the passage of energy through a boundary over arbitrary bathymetry. Radder (1979) and Booij (1981) develop this equation in the domain as an alternative to the elliptic equation. Berkhoff (1976) uses a downstream radiation boundary condition based on Hankel functions for the shoal problem, valid only in constant depth. The upstream boundary condition of Berkhoff (1976) for the same shoal problem is derived using the wave ray method. The limitation of the wave ray method is that for general purposes the rays frequently cross, resulting in no solution. The method used by the authors has the advantage of simplicity in that the boundary conditions are very simple to implement but none of the physical features are lost.

St. Vincent Island, located on the northwest Gulf of Mexico coast of Florida, U.S.A., preserves a well-developed beach ridge plain that is generally believed to have begun to form during the mid-Holocene period. This study evaluates the potential of optical stimulated luminescence (OSL) to appraise the proposed evolution and progradation of this strand-plain. Optical stimulated luminescence was used to obtain the ages of the quartz samples extracted from seven vibracores at two depth intervals. The single-aliquot regenerative-dose (SAR) OSL ages increase from the shores on the Gulf of Mexico to St. Vincent Sound. The younger ridge set yielded ages of 370 ± 49 to 1890 ± 292 years (AD 2004 datum) conferring an interridge accretion time range of 78 to 148 years assuming uniform sediment accumulation. The oldest ridge set yielded ages of 2733 ± 404 to 2859 ± 340 years, consistent with the estimated age based on archaeological materials of 3000–4000 years ago. For the southwestern beach ridge set, the ages provide insights on the aeolian accumulation and reworking processes effective throughout the ridges despite their vegetation cover. Our results highlight the potential of OSL as an application to use not only for dating but also for coastal dynamics assessments. The SAR–OSL ages presented herein provide new reliable absolute ages on the beach ridge sequence of St. Vincent Island and improve the age control on formation of barrier island sequences in the Florida panhandle region.

Mangrove surface elevation was measured by means of the Surface Elevation Table and Marker Horizon technique (SET-MH) in a range of settings in southeastern Australia. Despite sustained vertical accretion, surface elevation declined at most sites with the onset of an El Niño drought in 2001–2002. At these sites, the Southern Oscillation Index accounted for 70–85% of variability in surface elevation over a 3-year period. At deltaic island sites, this trend was not evident, an observation we attribute to lower terrestrial groundwater inputs. At one site (Homebush Bay), a high correlation was found between surface elevation and groundwater depth, monitored approximately every 2 weeks for 4 months. At the same site, the diurnal astronomical tide was also found to significantly affect mangrove surface elevation, although not to the extent of the El Niño drought. Models of the response of mangroves to sea-level rise on the basis of contemporary processes should account for short-term perturbations, such as climate variability at regional and local scales.

We recorded eight species of birds in the Laridae family on the Ilha Comprida beach (southern São Paulo State, Brazil), during weekly censuses over 3 years (1999, 2000, and 2001). These species were grouped into three clusters by their abundance, permanence, and time of beach-flat use. The first cluster was formed by Larus dominicanus, Sterna eurygnatha, and Sterna maxima, which were in high abundance and present on the flat in all years. The second cluster included Sterna hirundo and Sterna hirundinacea. Sterna hirundo were seasonally abundant, and all individuals migrated to North America during the reproductive season. Sterna hirundinacea were always present for short periods. The third group included species of low abundance: Sterna superciliaris, Sterna trudeaui, and Larus maculipennis. The number of species and the number of individuals probably fluctuated because of migration or movement between neighboring beaches.

The present work identified the patterns of spatial and temporal use of Boa Viagem Beach. The levels of use were determined during the dry and rainy seasons. Four areas with different environmental and social characteristics were considered. In eight 100-m-wide transects, ranging from the pavement down to the water line, the level of use was determined through counting of beach users throughout the day. The patterns of use of the beach were the same for summer and winter, but frequency was threefold higher in summer weekends. The most frequented days were the same between seasons, but not the same among areas. The number of beach users varied from 1–1610 in winter to 6–3610 in summer. The area occupied by beach users varied from 1.3 to 34.6 m²/person. The main arrival time was from 0930 h to 1130 h. The peak time of users was between 1130 h and 1330 h for all parts of the beach, during the whole week. The main departure time was 1530 h for all parts of the beach and days of the week. People seemed to prefer areas and stretches of the beach where the backshore was longer. The landscape was probably highly rated as an attribute in visitor's choice. The north and central parts of the beach are better preserved, and they were also more used. The south part of Boa Viagem is undergoing a severe erosion process, which made the beach disagreeable for some beach users. This was clearly reflected in beach use patterns.

During the last 50 years, the Spanish Mediterranean coast has experienced a massive influx of tourism that has affected the ecosystems adjacent to the coastline, triggering processes of regression and fragmentation. The changes between 1956 and 1996 are characterized and quantified here in a part of the coast next to Torredembarra (NE Spain) that occupies 470 ha. For this zone, maps of vegetation for 1956, 1985, and 1996 were prepared with a common legend of 14 units. A numerical matrix was generated with the Geographic Information System to detect the spatial-temporal variations between units; furthermore, several landscape indicators and parameters were assessed. All of them show evidence of the accelerated substitution of an agricultural landscape and extensive areas of coastal vegetation by an urban landscape: agricultural land diminished by 64.3% and coastal vegetation by 55.3%, whereas urban areas increased by 2326.5%. If present conditions persist, in the next 30 years urban areas will occupy 87% to 100% of the territory. We also emphasize the importance of a reserve zone (natural area of interest) of 45 ha in the conservation of some coastal natural habitats listed in directive 92/43/EC. At present, this reserve creates a “buffer” effect that restrains the regression of these habitats and shows in addition a spatial continuity lacking in unprotected sectors. We also warn of the risk of disappearance of unprotected natural habitats in the short term due to urban growth and summer tourism.

The Holocene environmental evolution of the Bojuru region, Rio Grande do Sul state, southern Brazil, was inferred from seismic, geochronologic, sedimentologic, and paleontologic data. The absolute ages of two samples, determined by the ¹⁴C method, are 9400 ± 140 Cal BP and 7370 ±150 Cal BP. On the basis of lithology and palynomorph and diatom data, the six stages of paleoenvironmental development of this region were chosen. Layers of muddy sediments characterized by a significant incidence of marine palynomorphs and marine and estuarine diatoms were deposited during the Early and Middle Holocene. Seismic records (3.5 kHz) revealed a prominent buried paleochannel that can be correlated to the present Barra Falsa channel. The main period of the channel incision was related to the last regressive event of the Late Pleistocene. During the last Holocene transgression, this paleochannel was filled up by fluvial, estuarine, and marine sediments. The integrated analysis of data reveals that the Barra Falsa feature resulted from a former channel connecting the Patos lagoon and the Atlantic Ocean. The closure of this inlet channel is attributed to shifts in the sedimentation milieu related to the transgressive maximum and subsequent regression during the Late Holocene.

In 2001, Helike Project archaeologists found traces of the coastal site of Classical Helike, a city destroyed and submerged by an earthquake and tsunami in 373 BC. Nearby they also found remains of its prehistoric predecessor, an Early Bronze Age (EBA) settlement dating from ca. 2500–2300 BC. Both sites are on land, 3 to 5 m below the surface of a coastal fan delta southeast of Aigion, on the Gulf of Corinth in Greece. To investigate the environmental history of the delta and the ancient sites, we analyzed microfossils, mainly ostracods and foraminifers, in sediments from boreholes and archaeological trenches. Although the area is now dry land, microfossil assemblages indicate ancient coastal aquatic environments over a wide range of salinity at the time and place of sediment deposition. The EBA site is covered by clay and sandy clay containing freshwater, brackish, and marine microfossils. The Classical site is covered by silty sand and silty clay containing mostly freshwater and brackish microfossils. The EBA site was apparently submerged in a coastal lagoon, perhaps due to an earthquake. The site was subsequently silted over and uplifted. Some two thousand years after the EBA destruction, the historical earthquake and tsunami destroyed Classical Helike and submerged its ruins in a lagoon. Continued uplift and sedimentation then led to the emergence of the present delta. The occurrence of severely abraded or fragmented shells of marine and brackish microfossils in a broad stratum of possible Classical age suggests the action of a tsunami.

The rare earth elements (REEs) in the sediments of the Pichavaram mangrove of the Coleroon-Vellar estuarine complex in India were measured by inductively coupled plasma mass spectrometry. The light rare earth elements (LREEs) were more enriched than the heavy rare earth elements (HREEs) and the Eu anomaly was relatively weak. No obvious differences were found among the different zones of the mangrove except for a few metals and very few REEs. Intense weathering of the surface crustal areas controls their distribution. The shale-normalized values indicate a similar pattern except for a few fluctuations in their distribution patterns. The variation in the enrichment of HREEs was controlled by the salinity gradient and inputs from estuarine zones. Correlation and factor analysis also explain the contribution from the continental weathering followed by other processes like salinity control, input from anthropogenic sources, etc. The enrichment factor substantiates that most of the REEs have weathering sources and are altered in the complex biogeochemical processes operating here. Few metals were derived from anthropogenic activities but were generally below the contamination levels. The Ce, Gd, and Eu ratios confirm the natural and anthropogenic source. In general, the interior channels and high-salinity zones were more enriched with HREEs than LREEs (i.e., HREEs seemed to be trapped more here). The mangroves contribute around 70%–80% of the LREEs (including middle rare earth elements) and 20%–30% of HREEs to the adjacent sea.

The nearshore habitats of western Biscayne Bay, a shallow lagoon adjacent to the city of Miami, are influenced by salinity fluctuations caused by freshwater discharges from canals. Benthic communities in these susceptible littoral habitats have been underrepresented in monitoring programs because of the difficulties associated with boat access. In the present study, we implement a geospatial video-based survey technique, the shallow-water positioning system (SWaPS), to document the abundance and distribution of benthic organisms in these shallow habitats. Mounted on a shallow-draft vessel, SWaPS integrates a global positioning system receiver with a video camera such that each video frame recorded is stamped with position information, date, water depth, heading, and pitch and roll. The georeferenced digital frames collected can be easily analyzed to document patterns of abundance and distribution of submerged aquatic vegetation and other benthic organisms.

The field surveys conducted using SWaPS showed that species distributions are influenced by their respective tolerances to salinity patterns. Seagrass species with relatively high tolerance for low, variable salinity (e.g., Halodule wrightii and Ruppia maritima) tend to have high abundance only in areas influenced directly by canal discharges, while species with relatively limited tolerance for low salinity (e.g., Thalassia testudinum) tend to increase in abundance with increasing distance from the mouths of canals. The use of video-based surveys with high spatial precision facilitates rapid, cost-effective, and repeatable monitoring of shallow marine benthic communities. The most attractive features of this system are (1) the ability to cover large areas rapidly without divers and (2) the ability to return to precise locations without establishing permanent markers (e.g., stakes). Moreover, the georeferenced digital images collected with SWaPS are a valuable permanent visual archive that can provide the baseline information needed to evaluate long-term patterns of change in environments such as western Biscayne Bay that are subject to increasing pressure from human activities.

In order to elucidate microbial response to the benthic environment in trench and flat seabed sediments, dynamic changes in the sediment microbial community and the water quality of overlying water were evaluated during summer and autumn in Tokyo Bay, Japan. A large amount of nutrients accumulated in the trench during summer when stratification occurred, which stimulated the sediment microbial growth, resulting in higher microbial density compared to the flat seabed sediment. Additionally, predominant ubiquinone species in the two sediments were ubiquinone with 9 isoprene units (Q-9) and Q-8, respectively, while menaquinone with 6 isoprene units (MK-6) dominated. Hence, the different bottom shapes were expected to produce distinct microbial environments. In autumn, the convective mixing of seawater resulted in the disappearance of stratification and the deposition of nutrients onto the flat seabed sediment, which contributed to excessive microbial growth. During this transition period, Q-containing bacteria dominated with lag time instead of MK-containing bacteria. At the same time, the molar fraction of MK-6 that might correspond to sulfate-reducing bacteria also rapidly decreased. However, this microbial change was not observed in the trench since it kept anaerobic conditions longer. Multidimensional scaling analysis indicated that dissolved oxygen of the bottom water can drive microbial community shift.

Stratification and mixing dynamics in estuaries are controlled by different physical processes, which determine estuarine hydrodynamics and the transport of plankton, nutrients, and organic compounds. In this paper, we present an investigation of features that control the dynamics of the Itamaracá estuary, Pernambuco (northeastern Brazil) through quantitative and comparative analyses between stratification processes (surface heating, rainfall precipitation, and differential advection of the longitudinal density gradient resulting from the vertical velocity structure) and mixing processes (stirring of bottom tidal stress, stirring of surface wind stress, and surface evaporation). Thermodynamic and cinematic field data were obtained during rainy and dry seasons. Results indicate that mixing intensity in the water column was about one and a half to twice as high as the potential capacity of external forcing in promoting vertical stratification. The bottom tidal stirring was the most important cause of vertical mixing. A theoretical analysis showed that, during the dry season, the stratification timescale (30 min) was greater than the turbulence decay timescale (9–10 min) and also greater than the slack water timescale. During the rainy season, the stratification timescale (7 min) had the same order of magnitude as the turbulence decay timescale (9–10 min). The Itamaracá estuary is a vertically well-mixed/weakly-stratified system during both periods (dry and rainy), except during rainy slack water periods, when stratification can be expected. These theoretical results are in agreement with previous field data and recent works involving numerical simulations at the Santa Cruz Channel.

We analyzed the distribution and ecology of large gastropods inhabiting the continental shelf of Uruguay and the Río de la Plata estuary, in depths ranging from 4 to 62 m. Seven species belonging to Tonnidae, Ranellidae, Muricidae, Nassariidae, and Volutidae were collected. While the seven species recorded in this study have been previously reported for the Uruguayan coast, here we provide the first detailed description of its habitat preferences in terms of depth, salinity, and sea bottom temperatures. Clustering analysis of stations based on biological data (presence/ absence of species) indicated a spatial segregation of the large gastropods assemblages in three areas: estuarine, low specific richness, dominated by Rapana venosa; inshore (10 to 36 m), high richness, codominated by Zidona dufresnei and Pachycymbiola brasiliana; and offshore (21 to 62 m), intermediate richness, characterized by Z. dufresnei. Mean values for environmental parameters showed significant differences among clusters of stations. Direct developers were more ubiquitous than planktotrophic developers. On the other hand, the exotic planktotrophic species R. venosa dominated the estuarine area. This pattern is not coincident with predictions based on life history traits, such as dispersal capabilities; this suggests that generalizations in this respect are complicated and scale and species dependent.

A quantification of coastal erosion processes on a clay cliff in a cold temperate region was conducted. This study was based on a network of markers that were measured on a monthly basis from 1998 to 2003. During that period, the average retreat rate of the cliff was 1.5 m/y. Our results demonstrate that weathering is a more significant cliff retreat factor than hydrodynamic processes on fine sediment shorelines. This statement opposes conventional understanding. In fact, 65% of the annual cliff retreat took place through the winter season when the waves could not reach the foot of the cliff because of an ice foot. This erosion is caused by cryogenic processes in winter, particularly through freeze–thaw cycles, whereas desiccation and wave undercutting contributed respectively for 20% and 15% of the total annual retreat. The field measurements conducted before and after major storms, especially on October 29, 2000, illustrated that wave undercutting was negligible for the clay cliff. These results do not corroborate with previous studies showing that cliff erosion is mostly controlled by wave undercutting with negligible winter erosion. In a context of global warming, the intensity of cryogenic processes can become more important due to milder winters, an increase in the number of freeze–thaw cycles, and the reduction of the ice foot and snow cover (especially on south-facing cliffs directly exposed to solar radiation). This study demonstrates that the evaluation of sensitivity of coastal systems to climatic change should not be done just for sea-level rise and increased storminess, but also for other climatic parameters. Future research should also take into account approaches combining the studies of marine and terrestrial erosion processes.

Coastal erosion is a problem around much of the coast of Great Britain. This paper uses the example of Birling Gap in East Sussex to highlight a variety of problems associated with property boundaries on eroding cliffed coasts. The legal foreshore definitions (generally owned by the Crown) from English and Scots laws are compared with the use of tidal data from the nearest reliable tide gauge at Newhaven. With a Microsoft Excel spreadsheet model and shore profiling, these data are used to identify the extent of private property in the coastal environment at Birling Gap under both Scots and English law. The paper highlights that under both definitions, a small parcel of “land” exists at the base of the cliffs that is owned by the adjacent cliff top landowner. Therefore, the foreshores as defined in (Scots and English) law on the mainland of Great Britain do not fully enclose the envelope of coastal processes. Under Scots and English law, the foreshore is defined on the basis of tidal heights, irrespective of the mobility of the substrate that the foreshore boundary is drawn on. The cliff morphology at Birling Gap strongly suggests control by marine erosion; however, the tidal data from Newhaven suggest otherwise when compared with the shore profiles. A number of reasons are identified to explain a substantial difference in the height of the beach at Birling Gap and the observed tidal heights at Newhaven, including the distance from the tide gauge, the damping effects of tide gauges, and the morphology of the beach. We conclude that, under British property laws, a small area of the upper beach (which regularly changes in shape and size) is owned by the adjacent landowner and is technically under their control despite being regularly inundated by the tides.

Two storm events occurred in the southwest Pacific Ocean in March and July 2001 and generated large swell from the east–northeast that breached a small barrier complex at Abrahams Bosom Beach on the southeast coast of Australia. Both events breached the barrier and deposited sandy marine sediment more than 150 m into the back-barrier estuary. The sandsheets consist of graded beds that are generally less than 20 mm thick. The periodic storm-generated swells that strike the coast from the north to northeast are not in equilibrium with the ambient setting of north-facing embayments on this coast. Such north-facing embayments are likely to be breached during episodic high-energy events. This project provided an opportunity to determine the sedimentary characteristics of overwash sedimentation in an estuary from the southeast coast of Australia. The overwash deposits also provide a modern analog to assist in the characterisation of other Holocene overwash sandsheets identified from estuaries along the southeast Australian coast.

The germination and subsequent seedling establishment of Limonium emarginatum, an endangered and endemic halophyte of the Strait of Gibraltar, was studied under exposure to different NaCl concentrations (0, 2, 4, and 6%) in a laboratory experiment. We assessed final germination percentage, number of days to first and final germination, mean time to germinate (MTG), as well as seed viability and seedling survival. Increasing salinity delayed the beginning and ending of germination and reduced final germination percentage, inhibiting germination completely above 2% salinity. L. emarginatum exhibited the greatest germination in fresh water. When seeds were removed from all saline solutions, between 60% and 70% of final germination was recorded, although at hypersalinity, germination viability diminished. Salinity pretreatments had a stimulatory effect on germination since germination speed was higher for the recovery experiment than for the seed germination experiment. Transition between germination and seedling establishment was a critical phase, given that less than 50% of seedlings of L. emarginatum survived in distilled water and 5% survived at 2% salinity.

The Adour river mouth is located in Anglet, on the southwest coast of France, and it provides access to the commercial harbour of Bayonne. The navigation channel suffers from a recurring problem of silting and needs regular dredging. The construction of breakwaters and jetties has not solved the silting problem. Recently, a preventive trench was dug south of the channel to decrease the rate of siltation in the navigation channel.

Bathymetric data of the river mouth were monitored for 26 mo, and 40 bathymetric sets of data were analysed. During the investigation period, four dredging campaigns were carried out. The surveys provide a very unusual bathymetric record because the sampling in time is extremely dense for such data.

Eigenfunction analysis was performed along transects perpendicular and parallel to the direction of the river flow. These analyses are usually used to explain natural bathymetric or topographic evolutions. Here, there are also used to describe anthropogenic influences. The first spatial eigenfunction corresponds approximately to the mean bathy-metry over the study period. It does not show the preventive trench. This demonstrates that the trench is an ephemeral feature of the bathymetric record. The subsequent eigenfunctions represent the variations about the mean. The second eigenfunction explains the majority of the seabed evolution and reaches a maximum amplitude at the location of the preventive trench. The corresponding temporal eigenfunction presents important discontinuities during the dredging campaigns; its maximum amplitudes correspond to the maximum siltation, and its minimum amplitudes correspond to the dredging periods.

A two dimensional empirical eigenfunction analysis confirmed that there was little evidence for any directional bias in the seabed evolution. In conclusion, this study shows that empirical eigenfunction analysis methods can be a helpful tool for analysing the impact of dredging activities and could have a useful role in estuarine management planning.

One of the problems dealing with traditional water-monitoring methods is the need to collect water samples at the precise moment that faecal contamination is actually present; for this reason, the use of Mytilus galloprovincialis as an indicator of previously high bacteria concentrations in coastal seawaters was examined. These molluscs are able to integrate the fluctuations in pollutants, they are good representatives of the sampling area because they are sedentary, and they offer the advantage of being resistant to pollution. The research was conducted from September 2001 to October 2002, twice a month, in two coastal areas of Salento (Apulia, Italy), near the discharge channels. We analysed both natural and cultivated mussels. The latter were placed in cages, after checking their starting level of microbiological pollution. Bacteriological analyses were conducted simultaneously on mussels and their ambient water to detect total coliforms, faecal coliforms, faecal streptococci, and Escherichia coli.

The abundance of bacteria investigated was always higher within mussels than in the surrounding water where levels were sometimes undetectable. These results confirm the ability of mussels to concentrate and to retain bacteria into their tissues (recorders of present or even past microbiological pollution). Therefore, mussels can enable to detect a bacterial contamination that might be missed by standard water-monitoring methods, and we suggest they be included in routine microbiological investigations of coastal seawaters even in areas where these species aren't widely distributed.

In this paper, we present a model study on beach morphodynamic processes under the combined action of waves and controlled subsidence settlement. A special facility was designed to reproduce controlled seabed movements of a few millimetres. Vertical settlement is obtained with the use of wedges driven by the Archimedean screw. A prototype to model mechanical scale in this particular experiment showed the difficulties of reproducing a test duration that in the prototype could vary from 10 to 100 years. To solve this problem, tests were carried out reproducing only wave conditions able to give significant seabed movement. Measurements of wave heights, beach profiles, and shorelines were made. Results highlight the different effects of subsidence on beach profiles under storm surge, annual average wave conditions, and morphologic wave. Beach profiles and shorelines show a relevant increase in erosion, more evident in the vicinity of the still-water level because of the combined action of waves and subsidence. The net beach recession accompanying sea level rise by Bruun's Rule is different from that obtained under laboratory-controlled settlement. Equations describing quantitatively the erosion caused by settlement in the presence of wave subsidence were found.

The seaport at Ennore north of Chennai on the southeast coast of India was built in the year 2000 as an additional facility to the existing main port. An important aspect of the newly built port was protection from the erosion and accretion processes so very characteristic of this region. With a view to preventing downdrift erosion, artificial beach nourishment—a soft engineering measure—was provided by placing dredged material north of the port. This paper discusses performance of the beach fill and consequent shoreline oscillations on the adjacent coast caused by the creation of the new port. A combination of remote sensing based data, field surveys, and numerical models was used to (i) quantify the impact of the port on adjacent areas and (ii) assess performance of beach fill. Based on beach profile (planform) analysis for the period March 1999–December 2004 for the 1-km coast on either side of the port, it was noticed that the southern coast is accreting at a rate of 44 m/y while the northern coast is eroding at a rate of 46 m/y. Beach fill, 1000 m long and 500 m wide (avg.) with a transition length of 500 m at the northern end, underwent erosion, with 1.43 × 10⁶ m³ of fill material lost between 2000 and 2004, against a total beach fill of 3.5 × 10⁶ m³. Numerical simulations were conducted with near-shore wave climate derived from the parabolic wave transformation model, which indicated that beach fill was lost for 3 y considering the present rate of erosion. The presence of coarser sediments with positive skewness at the beach fill region is suggestive of favorable conditions for longevity of fill, and simulations conducted with increased transition length yielded better results in terms of performance of beach fill.

At 23 sites selected randomly around the island of São Miguel (Azores), video records were made at the depths of 5, 10, 15, 20, 25, and 30 m where a rocky substratum was present. Semiquantitative abundance data of the most common benthic organisms (algae and fixed/sedentary macroinvertebrates) were recorded in the vicinity of each depth reference point. Qualitative samples of the more conspicuous organisms were taken for confirmation of identification in the laboratory. At each site, substratum type, geographical orientation, and depth level were recorded. Multivariate analysis (nonmetric multidimensional scaling; analysis of similarity [Anosim] tests; similarity percentages [Simper] analysis) on the collected data enabled patterns of community distribution to be identified, as well as their relationship to abiotic factors. Since depth was found to be the sole determining factor for communities, it was the only one considered in the subtidal biotope survey protocol proposed here.

Anthropogenic alteration is a persistent and growing problem in coastal marine ecosystems. Changes may have occurred and gone undetected in coastal systems, and analysis of the molluscan death assemblage provides a useful tool for detecting changes where long-term observational monitoring of living organisms has not been conducted.

During the early 1980s, a series of experiments were conducted along Cross Bank, Florida Bay (inside Everglades National Park) to assess the effects of nutrient pollution by seabirds roosting on implanted marker posts on underlying sea grass beds. Over time, Halodule wrightii replaced Thalassia testudinum as the dominant sea grass at these altered sites. The present study focuses on the effects of this nutrient pollution on the molluscan death assemblage. Two parallel transects were established, one using altered sites as sampling stations and the other using unaltered, Thalassia-dominated localities. A series of surficial push cores were collected along these transects (24 in all) to compare compositionally the assemblages on both transects. Results demonstrate detectable differences in the composition of molluscan death assemblages between altered and unaltered sites. Several molluscs were virtually excluded by the change in sea grass composition, and results suggest that differences in root and blade morphology of the two sea grass species are causal factors. Therefore, the results demonstrate that molluscan death assemblages effectively recorded environmental change through some two decades in the study area and that similar environmental changes may be diagnosed elsewhere in coastal ecosystems on the basis of assemblage composition.

Located on the west margin of the Rio de la Plata estuary, the capital city of Buenos Aires is often affected by positive and negative storm surges due to strong southeasterly and northwesterly winds, respectively, which sweep the estuary. While positive surges cause severe flooding, negative surges affect navigation and drinking water supply. Since Buenos Aires is densely populated, a quantitative assessment of the variations in the regime of storm surges will help to develop policies for reducing their impacts. Changes in frequency, duration, and height of storm surges over the period 1905–2003 were determined from statistical analyses of hourly water levels. Calculations of the tidal constants used harmonic analyses of 19 y periods to account for any variation in the astronomical tide. Positive and negative surges were chosen from the residuals between observed levels and the predicted tide. The results show that the decadal averages of frequency and duration for positive surges have increased in the last three decades, but they have decreased for negative surges. The average decadal trends of the maximum positive and negative surges in each year, 1.46 ± 0.08 mm/y and 1.02 ± 0.09 mm/y, respectively, compare well with the relative mean water-level rise for Buenos Aires: 1.68 ± 0.05 mm/y. However, the height of positive surges has decreased in the last decade, and negative surges have become more intense in the last two decades.

River channelization is a widespread practice including river bed regulation worldwide. A primary goal of channelization is to rehabilitate the floodplain of rivers, modifying the energy regime and sediment transport capacity. This paper presents an application of this process carried out in the floodplain of the Lower Meric River, Turkey.

The application was performed by constructing a new channel in two regions along the river in the 1970s. Thus, the river was straightened, isolating its meanders to reduce the floods. These channel regulations are summarized in the paper by using satellite data and historical maps. The Landsat-7 enhanced thematic mapper (2001) image is the base data for interpretation of the present condition of the river channel, and the historical geomorphologic maps are used for the detection of the river bed prior to channelization.