A sequence of at least three Late and Middle Pleistocene coral reef terraces (Lower Terrace, Middle Terrace I and II), which are uplifted up to 45 m a.s.l., is conserved on Curaçao. The less uplifted Lower terrace (elevation 6 to 12 m above sea level) consists of two different coral reef formations: the Hato unit and the underlying Cortalein unit. The discontinuity between these two superimposed units is typically marked by a strong difference in the degree of weathering. Samples of coral in growth position were collected from the Lower Terrace (Hato and Cortalein unit) and the Middle Terrace I. ESR ages indicate a Last Interglacial age of the Hato unit of about 122 ky BP, and a correlation with the Last Interglacial sea level maximum (stage 5e). The ESR age of the underlying Cortalein unit is about 216 ky BP (stage 7). Palaeo sea level calculations imply a correlation with the youngest of three Penultimate coral reef terraces located on the island of Barbados, which was uplifted more strongly than the island of Curaçao. No equivalents of older Penultimate Interglacial coral reefs and of the Interglacial stage 9 were found. Middle Terrace I could be at least as old as stage 11 (approx. 400 ky BP), however, it could also be more than 500 ky old.

Lake Annecy in Haute Savoie, France, receives about two-thirds of its fluvial input from three rivers that flow to its southern end-point. The channels of the Eau Morte, Ire, and Bornette rivers are almost completely channelized in their lower reaches as a result of human activity, with flow contained along parallel, but separate, paths from headlands in the proximal drainage basin directly to the lake. Petrographic data from river samples collected in this study serve to differentiate sand-size material carried by each fluvial system. Proportions of the dominant (limestone) and five additional (dolomite, quartz, gypsum, rock fragments, and ‘other’) components in the 3 rivers are more closely related to source supply than to fluvial transport effects or sampling strategy. Of the 7 components, mica best records the influence of depositional mechanisms. Much of the carbonate sand and coarser material at the lake shore is derived from widespread Mesozoic outcrops. Non-carbonate sand input, partially resulting from erosion of glacial till deposits and pedogenic horizons in the southern drainage basin, provides key compositional markers to differentiate between sediment carried to the lake by each river.

Until several centuries ago, deposits of the Eau Morte, Ire, and Bornette flowed to the Bou du Lac, and formed a merged, multifluvial lacustrine delta. As drainage and channel containment projects related to agricultural development intensified in lake margin lowlands, the 3 channels were separated on the delta surface, allowing bypass of river material directly onto subaqueous deltas in the lake. Specific mineral assemblages, especially quartz, mica and rock fragments, may prove useful as key tracers of human-altered sediment between the margin and deeper lake sectors.

Friedrichs and Perry (2001) have hypothesized that exogenous sedimentation is a vital part of a feedback system (with tidal height, marsh elevation and local vegetation) that keeps the marsh surface in equilibrium with sea level. This study investigated the relationship between local sedimentation rates, presence of overlying vegetation, distance from tidal channel, and local elevation in two marshes located in the San Francisco Estuary. Exogenous sedimentation rates measured using sediment traps on marsh plains at approximately MHW were found to be much lower than expected. Sedimentation rates were highest closest to tidal channels, regardless of overlying vegetation, but declined rapidly on the inland portions of the marsh and were never high enough to build the marsh plain at rates greater than 0.91–1.37 mm m⁻² yr⁻¹. Maintenance of tidal marsh elevations solely by exogenous sedimentation within the San Francisco Estuary seems unlikely. Observations that local marshes keep pace with sea level rise implicate local productivity as the source of increased sediments.

Ground penetrating radar studies of four representative active back-barrier dunes, combined with radiocarbon and photon-stimulated-luminescence dating techniques and soils analysis, reveal phases of alternating dune activity and stabilization along the North Carolina–Virginia coast. Two smaller dunes represent only the current phase of dune activity. Two larger dunes preserve evidence of three phases of dune development (ca. 740, 1260 and 1810 AD) and intervening phases of soil development. Climate, particularly moisture conditions, played a part in the timing of dune activity and stabilization events. All three dune phases are associated with drier conditions whereas soils formation is associated with humid conditions. Modern (phase 3) dunes are more widespread along the coast and their formation is attributed to a combination of dry conditions, increased storminess associated with the Little Ice Age, and rising sea level. Tidal inlet closing and storm overwash processes likely provided sediment point sources for individual dune masses. The longer history and much greater volume of dune sand in the area of the two larger dunes suggests a greater sediment supply in this locality.

Seismic cross-sections and drillings, which were carried out as part of a larger research program in the area of Dor on the southern Carmel coast of Israel, indicate that the young stratigraphic sequence consists of sand that unconformably overlies dark clays, with the dark clay unit becoming reddish-brown paleosol at the bottom. This sequence of sands, clays and paleosol overlies the irregular topography of the late Pleistocene calcareous sandstone (locally named kurkar). The topography of the kurkar consists of continuous, undulating areas. The dark clays in the study area were deposited in marshes that filled two different depressions. The sediments contain foraminifera, ostracodes, and mollusks (bivalves and gastropods). Most of the well-preserved species indicate low to brackish water salinity. The ages obtained for the dark clay unit in the Dor area, both by using ¹⁴C and infrared stimulated luminescence (IRSL), are given in thousands of years. At the northern depression, the oldest age obtained by ¹⁴C is 17,915 ± 185 BP, while IRSL obtained a date of 21,800 ± 1,900 yr. for the same sample. At the southern depression, the oldest age of the clay obtained by ¹⁴C is 16,680 ± 1200 BP, while IRSL obtained an age of 13,800 ± 1,000 yr. in one borehole and ¹⁴C age of 12,165 ± 100 BP in the second borehole. The top of the clay unit is dated by ¹⁴C to 8,770 ± 60 BP and 8,650 ± 75 BP in the southern depression, and to 9,520 ± 130 BP in the northern one. A low sea level is indicated during the entire period. At 8500 BP, which is the youngest date for the existence of coastal marshes at Dor, the sea level was probably around −20 m, but certainly not higher than −13 to −16 m, and the coast was at about 1.5−1.0 km off the present one. Shortly after the drying up of the marshes, human sedentary started at the Carmel coast on top of the dark clay unit, beginning at the Pre-Pottery Neolithic B period (that ends at about 8000 BP), and continued through the Pottery Neolithic and the Chalcolithic periods (up to ca 5100 BP). Only during the Middle Bronze IIA period, at about 4000 BP, when sea level rose to about −1m to −2 m, people started to settled on the kurkar hills along the coast and sands started to accumulate in the area. The sea reached its present level in the last 2000 years, carrying the sands that cover the coastal clays and the early settlements mentioned, and creating the relatively smooth present-day coastline.

A simple mathematical model was used to test the hypothesis that the gradient and other aspects of the morphology of shore platforms in argillaceous rocks are determined by the number of wetting and drying cycles experienced at different elevations within the intertidal zone. Three model variants were considered: downwearing by wetting and drying on a pre-existing wave-cut surface; downwearing occurring simultaneously with backwearing by waves at the high tidal level; and downwearing combined with simultaneous backwearing by waves throughout the intertidal zone. Wetting and drying and tidal-duration distributions were obtained for four areas, representing tidal ranges from 1 m to 9.3 m. The amount of downwearing was made proportional to the wetting and drying frequency, and it therefore varied through space and time in response to changes in platform elevation. The model suggested that wetting and drying can produce very gently sloping shore platforms, especially in microtidal environments. Although low gradients were also produced by weathering under favourable conditions in macrotidal environments, they were significantly greater than those produced under the same conditions in low tidal range environments. Fairly high gradients, ranging up to about 2.5°, were produced in macrotidal runs with slow wave erosion and weathering. The model suggests that wetting and drying can provide an additional or alternate explanation to that of wave erosion for the relationship that has been reported between tidal range and platform gradient.

Wave propagation around and inside a harbor is conventionally studied by numerically solving a representative equation of short-wave progression or by taking actual measurements on a physical model. Although the numerical schemes yield workable solutions, underlying assumptions as well as noticeable difference between the resulting estimations and actual measurements leave scope to employ alternative approaches. The current study is an attempt in that direction and is based on the approach of neural networks. Modeled to imitate the biological neural network prevalent in human brains, an artificial neural network represents interconnection of computational elements called neurons or nodes, each of which basically carries out the task of combining inputs, determining their strength by comparing the combination with a bias (or alternatively passing it through a non-linear function) and firing out the result in proportion to such a strength. The network is first trained with examples, the strengths of interconnections (or weights) are accordingly fixed and then it is readied for application to unseen inputs. The applications of neural networks have now spread across all disciplines of ocean engineering, namely, harbor, coastal, offshore and deep-ocean engineering, and are directed towards function approximation, optimization, system modeling including parameter predictions. Advantages of the ANN schemes are improved accuracy, ease in application, reduced data requirement and so on.

In the present work a feed forward modular neural network was developed in order to estimate attenuation of wave heights along the approach channel of a harbor starting from seaward boundary and ending at the harbor entrance. The trained network was found to satisfactorily follow the expected trend of wave height attenuation along the harbor channel. When tested for unseen input it yielded values of wave heights close to the numerical and physical models. The network also properly simulated the effect of variation of wave period as well as that of angle of wave attack on wave attenuation.

Sub-tidal, reef-lagoon surficial sediment samples from Discovery Bay, north Jamaica were analysed in order to quantify the impacts of anthropogenic bauxite inputs on trace metal (Fe, Zn, Mn) levels and sediment characteristics. Contaminant levels exhibit marked spatial variations, but are highest across central and southern parts of the bay and primarily reflect wind blown inputs, modified by subsequent suspended sediment transport. Highest contaminant levels (Fe—13,701 ppm, Mn—237 ppm, Zn—74 ppm) occur immediately adjacent to, and just north-east of, a bauxite loading terminal in the south-west of the bay. Sites of high sediment contamination are negatively correlated with per cent CaCO₃ content, indicating the diluting effect of bauxite on the carbonate substrate. At high contamination sites CaCO₃ levels are reduced to 63.7% and are in the range of 75–80% across much of the central and southern area of the bay. Magnetic susceptibility level measurements are positively correlated with iron and negatively correlated with CaCO₃ content, and indicate the potential for using magnetic susceptibility measurements in metal contaminant tracing studies in carbonate environments. Whilst metal contamination levels are low compared with many clastic-dominated systems, and are currently at levels unlikely to impact the reef biota, the data indicate both the progressive contamination of this previously carbonate-dominated lagoon environment, and the potential for such terrestrial inputs to impact upon sediment characteristics in such restricted settings.

Over the past thirty years, the coastal counties have shifted from traditional maritime activities such as fishing and boating, to a more service-oriented, and tourism-dependent economy. A key to economic growth in the coastal states has been the strength of the travel and tourist industry. This study links a regional model of tourism-generated earnings to a GIS model to quantify the relationship between the relative size of the travel and tourism sector in each county and the county's proximity to the coast. We find that tourism-related earnings, as a percent of total earnings, are concentrated in counties that lie within forty km (25 miles) of the Atlantic, Gulf and Pacific coasts of the United States. In contrast, the share of earnings attributable to tourism is not sensitive to distance from the coast for counties that are further than forty km (25 miles) inland. The literature on beach quality suggests that coastal tourism is dependent on clean, broad and sandy beaches. Key unanswered questions are: 1, the importance of beach quality to the tourism industry, relative to other amenities such as weather and the presence of cultural attractions; and 2, the degree to which a common set of causes explains migration patterns, tourism, and economic development in the coastal zone.

Influx of hydrocarbon contaminants to the coasts of United Arab Emirates is a serious environmental problem that threaten marine habitat. This paper presented two datasets to extract information on hydrocarbon pollution in marine environment utilizing visible to near infrared portion of the electromagnetic spectrum. The datasets used were Land-sat ETM images for Dubai and Fujirah coasts, and experimental visible to near infrared spectra of petroleum hydrocarbon in water. The experimental spectra were measured using GER 3700 spectroradiometer. The study applied image analyses techniques and radiance ratios on corrected Landsat ETM images in order to detect oil spills from tankers. The reported results demonstrated proper bands or channels with techniques useful for oil spill detection using images of Landsat ETM . The study found that radiances extracted from visible and near infrared images are useful to assess the thickness of hydrocarbon spills. The study also found that areas of thicker oil are slightly brighter because they suppress the signal from the underlying seawater. The spectra of GER 3700 provide potentials for identification of possible contaminants as well as classification within a particular hydrocarbon category (e.g. aromatics). The presented techniques hold promise for rapid analysis of petroleum hydrocarbons in marine environment.

Many contaminated sediments and dredged material mixtures of cohesive and non-cohesive sediments occur in wave-dominated environments. In-situ analysis is imperative in understanding the erosion and transport of these sediments. Recent research efforts have developed a flume with unidirectional flow that can measure in-situ sediment erosion with depth (SEDflume). However, the flow regime for the SEDflume has limited applicability to wave-dominated environments. Therefore, a unique device, called the SEAWOLF flume, was developed and used by Sandia National Laboratories to simulate high-shear stress erosion processes experienced in coastal waters where wave forcing dominates the system. The SEAWOLF is capable of testing in-situ or laboratory prepared cores. Erosion rates of cohesive and non-cohesive sediments prepared in the laboratory were determined in oscillatory and combined oscillatory and linear flow regimes. Results of these tests were compared to results from the unidirectional SEDflume. Although maximum shear stresses for oscillatory flows were as high as 7 Pa for the tests, the associated erosion rate for specific sediment over the entire wave cycle were comparable to much lower shear stresses found for constant, linear flows. For example, sediment exposed to a maximum of 7 Pa over a 15 s period resulted in erosion rates similar to results for a constant linear shear stress of 3.4 Pa. Analysis of results for all sediments tested led to a determination of values for an effective shear stress that relates wave-induced erosion to linear flow induced erosion.

Since approximately 5200 cal yrs BP, five sets of eight to nine beach ridges were built and preserved along the northwestern Peruvian coastal desert (3°30′S–9°S). Potential ridge-building mechanisms in the hyper-arid environment of northwest Peru include El Niño floods and storms, seismic activity, and sea-level change, as well as more gradual climate changes that affected coastal morphology. Image processing and Geographic Information System (GIS) methods were used to analyze aerial photographs and measure historic coastal patterns along three beach-ridge plains over a 37-year time period. Coastal features were digitized from image mosaics of each ridge plain at different time intervals from 1946 up to 1983. Progradation rates were examined at ridge locations north of the Chira River and Piura River, as well as at the base of ephemeral stream valleys in Colán. The total change in beach area was measured from historic aerial photographs taken at different time intervals. The resulting measurements showed that sediment distributed by El Niño storms was redeposited along the shoreline within a few years following each event. The difference between the frequency of El Niño events (currently 2–7 years) and the rate of ridge preservation (1 per 500 years average) suggests that individual ridges may be composites of multiple depositional events, or that ridges result from the rare convergence of multiple processes and conditions. A change in style of ridge formation in all studied beach-ridge sets correlates with, and may be explained by, change in the frequency of El Niño events at about 3000 cal yrs BP.

The total and bioavailable contents of Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in surface sediments from 77 sites in the Altata-Ensenada del Pabellón (AEP) lagoon complex were determined by Atomic Absorption Spectrometry, after inverted aqua regia (HNO₃/HCl 3:1) and sodium acetate 1M (adjusting pH = 5 with acetic acid) digestion, respectively. The ratio between the bioavailable fraction and the total concentration (BAP: BioAvailable Proportion), for each metal, was examined according to the chemical parameters of the bottom waters (dissolved oxygen and salinity) and geochemical characteristics of the sediments (organic carbon and total Al, Fe and Mn contents). Highest bioavailable concentrations of metals were associated with agricultural discharges and Culiacán River inputs. According to the Canadian Sediment Quality Guidelines, the Pb bioavailable content can produce adverse effects on organisms. Total concentration of Cu, Mn, Pb and Zn played an important role in the fractioning of these metals. Organic carbon, fine sediment, Fe and Mn hydroxides and aluminosilicates influenced the behaviour of Cu, Fe Ni and Zn BAP's.

Wave transformation in the region of Cape Fear, NC, is investigated through field measurements and application of the numerical spectral wave model STWAVE. Field data on offshore and nearshore directional waves, high-resolution bathymetry, tide, and wind were collected starting in the fall of 2000. The applicability of using offshore gauge data as input along the model boundary was evaluated by additional modeling on a coarse grid extending seaward beyond the influence of irregular shelf bathymetry. Model evaluation is presented based on three storm events. For nearshore model and gauge results paired in time, the root-mean-square error in wave height is 0.2–0.5 m and in wave direction is 14–24 deg. The relative importance of accurate bathymetry, tide, wind, nonlinear wave-wave interactions, and spectral shape (measured versus parameterized) are examined with model sensitivity studies. Impacts on potential longshore transport computations are also considered. High-resolution bathymetry is found to be most significant in reducing model versus gauge differences. Use of parametric input spectra gave comparable results to input of measured two-dimensional spectra for the selected storms.

In this work, we analyze the seasonal evolution of a Mediterranean pocket beach and its response to different storm episodes. Magalluf, an intermediate medium sand beach located in the Bay of Palma (Balearic Islands) was monitored by topographic levelling during 14 months. Near the beach, a Posidonia oceanica meadow covers most of the seabed and appears to influence the cross-shore beach adjustment. The low variability observed during the sampling period was perturbed by two storm events that caused significant beach evolution and sediment transport. The first storm gave rise to waves from the SE, significant height = 2.4 m, cross-shore sediment transport and along-shore net sediment exchange that resulted in decreased dry beach extension to a minimum. The second storm was characterized by strong northeasterly winds and generated a set-up of 0.5 m and a nearshore drift reversal that redistributed sediment from the berm crest to the beach face, thereby increasing beach extension. Results from numerical simulations of wave propagation show the circulation patterns during both events and their influence on the beach morphology. In general terms, the beach exhibited a homeostatic behaviour characteristic of an equilibrium system.

The successful management of fine-grained coastal environments relies on an understanding of, and an ability to predict, their likely future behavior. The latter depends not only on the hydrodynamic conditions to which these coastal systems are exposed, but also on characteristic surface properties that determine erosion shear strength and thus surface stability. Due to the inaccessibility of intertidal areas, precise ground-based measurements of mudflat stability are difficult to conduct. Remote sensing can provide full spatial coverage and non-intrusive measurement. As stability changes on mudflats are linked to subtle differences in mudflat surface characteristics, they can potentially be mapped by hyperspectral data. This paper reports on a study aimed at assessing the suitability of hyperspectral data for estimating mudflat characteristics related to stability. Hyperspectral images were collected along with near contemporary ground measurements. An unsupervised classification resulted in a map that reproduced observed thematic and topographic features, thus highlighting the close link between topography and surface sedimentary characteristics resulting in distinct spectral signatures. Multiple regression analysis was used to relate surface characteristics to hyperspectral data to construct regression equations. Erosion shear stress was estimated directly from the hyper-spectral data and also by a relationship with surface characteristics. The results of the thematic class map matched well with the known situation at the site during image acquisition. The quantitative information on surface characteristics suggest that the use of hyperspectral data for the assessment of erosion shear stress, surface stability, and thus the likely future behaviour in this dynamic environment can contribute to a significant improvement in the information needed for the successful management of shallow coastal systems.

This paper deals first with the formulation of a three-dimensional numerical model intended to determine the spatial and temporal evolution of the oceanic circulation in coastal zones under the effects of various oceanic and meteorological constraints. Simulations are based on the Mobeehdycs model which was developed through collaborative work of several laboratories. Then, the paper presents the results of the application of the model to the continental shelf of French Guiana under academic but realistic climatic conditions. The application required the adaptation of the model and the use of appropriate techniques for solving the equations accounting for the peculiarities of the local constraints. The application is of importance as, because of the lack of systematic observations, the current, salinity and temperature fields at the site are poorly known. A better knowledge of these fields is recognized as of fundamental interest for a characterization of the site from the biological and the ecological viewpoints. The results clearly show the effects of the external forcing (wind and rivers) on the fields evolution, at the surface and with respect to the depth. The time scales of these evolutions as well as their mutual influence are identified. Finally, the results agree, at least qualitatively with some of the few observational results available at present.

From 8/95 to 2/01, we investigated the ecological effects of intra- and inter-annual variability in freshwater flow through Taylor Creek in southeastern Everglades National Park. Continuous monitoring and intensive sampling studies overlapped with an array of pulsed weather events that impacted physical, chemical, and biological attributes of this region. We quantified the effects of three events representing a range of characteristics (duration, amount of precipitation, storm intensity, wind direction) on the hydraulic connectivity, nutrient and sediment dynamics, and vegetation structure of the SE Everglades estuarine ecotone. These events included a strong winter storm in November 1996, Tropical Storm Harvey in September 1999, and Hurricane Irene in October 1999. Continuous hydrologic and daily water sample data were used to examine the effects of these events on the physical forcing and quality of water in Taylor Creek. A high resolution, flow-through sampling and mapping approach was used to characterize water quality in the adjacent bay. To understand the effects of these events on vegetation communities, we measured mangrove litter production and estimated seagrass cover in the bay at monthly intervals. We also quantified sediment deposition associated with Hurricane Irene's flood surge along the Buttonwood Ridge. These three events resulted in dramatic changes in surface water movement and chemistry in Taylor Creek and adjacent regions of Florida Bay as well as increased mangrove litterfall and flood surge scouring of seagrass beds. Up to 5 cm of bay-derived mud was deposited along the ridge adjacent to the creek in this single pulsed event. These short-term events can account for a substantial proportion of the annual flux of freshwater and materials between the mangrove zone and Florida Bay. Our findings shed light on the capacity of these storm events, especially when in succession, to have far reaching and long lasting effects on coastal ecosystems such as the estuarine ecotone of the SE Everglades.

The rapid rise and fall of coastal sea level due to tides and storm surge complicates the application of hydrodynamic models that use constant lateral boundaries in the region where sea level change falls within the tidal range or between the negative and positive surge extremes. In order to enable a hydrodynamic model for use in tidal or surge zones, an inundation and drying scheme must be incorporated into the hydrodynamic model. In this study, a mass-conserving inundation (wetting) and draining (drying) scheme is incorporated into a three-dimensional hydrodynamic model (the Princeton Ocean Model, often referred to as POM) for coastal ocean and estuarine systems. This coupled hydrodynamic and inundation modeling system is tested in an idealized lake/estuarine setting. The results show that: 1) incorporation of the inundation/drying scheme into the POM enabled its application in shallow water systems with time-dependent coastal boundaries; 2) the mass conservation constraint used in the inundation and drying scheme eliminates the problem of artificial flooding associated with the imbalance of water mass that is typical of a non-mass-conserving schemes; 3) using vertically-averaged flow as flooding velocity resulted in a reduced flooding area as compared to the cases that use the surface flow as the flooding velocity. This is partly due to the fact that vertically-averaged flow tends to be weaker and directed more parallel to the coastline than the surface flow.

This paper examines the applicability of several empirical relationships for the performance of shore-parallel breakwaters at Sea Palling in Norfolk, UK. The research presented here compliments the work of Axe et al. (1996), who applied the models of Pope and Dean (1986), Suh and Dalrymple (1987), Ahrens and Cox (1990) and McCormick (1993) and compared their predictions with observations of beach response to the Elmer offshore breakwater scheme in West Sussex, UK. When these models were applied to the Sea Palling breakwaters, they generally revealed large inconsistencies in the predicted beach response. It is suspected that the inability of these methods to correctly predict beach response at this location is most likely caused by the overriding influence of factors such as wave transmission, longshore drift and a large tidal range, over geometrical relationships in the scheme design.

With tourism industry becoming the most important economic activity along the northwest cost of Baja California, new and expensive coastal developments are being built, increasing the relevance of gathering local wave data, even when this span a short period of time. Moreover, the value of this wave data improves if they are used to show that deep-water wave characteristics obtained from a remote location can be extrapolated to fairly represent local wave conditions. In this work wave observations during winter 2001–2002 in four sites within Todos Santos Bay, Baja California, Mexico, are used to document wave characteristics and their spatial variability within the Bay. The possibility of extrapolating into the Bay deep-water wave data from a remote location is also investigated. Results show a marked wave height spatial variability within the Bay, where in some places wave heights can be as much as 2.5 times higher than those measured at other sites. Wave height spatial variability is induced mainly by a combination of a shoaling effect, a convergence of energy, induced by wave refraction as waves enter the Bay, and a shelter effect, produced by the presence of Todos Santos Islands. Regression analysis between wave heights inside Todos Santos Bay and a deep-water station in southern California show a highly coherent wave climate between both places which provides the opportunity to reconstruct the wave climate for Todos Santos Bay from the long-term deep-water wave measurements.

Excessive human-derived nutrient availability has been implicated as a primary driver in the decline of the water quality and biota of coastal ecosystems. In 2003, seven sites along an urbanized section (∼100 km) of the Atlantic littoral coastline in east-central Florida were assessed for the bio-availability of the primary nutrients nitrogen and phosphorus. Ratios of dissolved inorganic nitrogen (DIN = nitrate nitrite ammonium) to soluble reactive phosphorus (SRP) in 74 beach water samples averaged 8:1, indicating strong water column nitrogen-limitation. DIN concentrations ranged from 0.69 to 8.11 µM with a grand mean of 2.10 µM, a value two-fold above the reported threshold value of ∼1 µM that saturates growth of Florida red tide, Karenia brevis and macroalgae species utilized in this study, such as Ulva lactuca. The majority (mean = 56%) of this DIN was in the form of ammonium, even during a peak upwelling event in June and August, suggesting the importance of anthropogenic land-based nitrogen as the primary N source. Macroalgae from subtidal sabellariid worm reefs were assessed for δ¹⁵N. At all study sites, macroalgal tissue mean δ¹⁵N values ranged from 8.7 to 9.9‰, values similar to those in macroalgae from sewage-polluted coastal areas, such as Boston Harbor. Many of the abundant macroalgae collected on these reefs, including Ulva lactuca, Chaetomorpha linum, Gracilaria tikvihae, and Caulerpa prolifera, are known sewage indicator species in other eutrophic coastal water bodies receiving excessive anthropogenic nutrient loads. These results suggest the need for improved nutrient removal in wastewater treatment facilities that discharge nearly 100 million liters of secondary-treated sewage effluent/day into the highly transmissive silica-sand barrier island of Brevard and Indian River Counties in east-central Florida.