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Breaking waves transport momentum, gas, and sediment vertically. Recent particle image velocimetry (PIV) measurements have elucidated the coherent vortex and turbulence structures under breaking waves. However, clarifying three-dimensional fluid motion under breaking waves with PIV remains challenging. Although particle methods have performed wave-breaking simulations, they have never been validated through velocity distributions for breaking waves above movable sediment beds. This study simulated the sediment transport process under plunging waves using a 3D Lagrangian fluid-particle mixture model. The investigation focuses on the first wave plunging for a fundamental investigation. Our simulation shows the instantaneous velocity distributions at different wave phases, which agree with the PIV measurement. A physically-based turbulence extraction method is introduced: a numerical filter based on the coherence between the water elevation and horizontal velocity. Visualized three-dimensional vortex and turbulence structures are consistent with previous studies. The transport equation of the kinetic turbulence energy investigates the turbulence budget near the bed surface and emphasizes the negative contribution of the fluid-particle interaction. Our findings show that a contribution of the pressure gradient to offshore sediment transport. The pressure gradient is difficult to correlate to the water surface gradient and is derived from the large vortex induced by the plunging wave. [ABSTRACT FROM AUTHOR]

Context: Urbanisation is pervasive across landscapes and seascapes and leads to the loss, degradation and fragmentation of many natural ecosystems and this has widespread consequences for animals and the ecological functions they support. While the impacts of urbanisation are understood for many individual coastal ecosystems in isolation, it is unclear how these impacts influence animal assemblages and ecological functions across different coastal ecosystems within the same landscape. Objectives: We aimed to determine how urbanisation modifies fish and crustacean assemblages and the function of carrion consumption across multiple coastal ecosystems set within the same landscape in eastern Australia. Methods: We sampled fish and crustacean assemblages in three distinct coastal ecosystems (estuaries, rocky headlands and surf zones) with baited remote underwater video systems and quantified rates of carrion consumption using scavenging assays. Results: Urbanisation had negative effects on the richness and abundance of coastal fish and crustaceans and the ecological function of carrion consumption, and these impacts were almost always consistent across estuaries, rocky headlands and surf zones. Species richness and abundance were lowest at the most urbanised sites, whereas rates of carrion consumption were lowest at sites closest to urbanised areas, across all ecosystems. Conclusions: We highlight the negative effects of urbanisation on coastal fish and crustacean assemblages, and a vital ecological function, and the consistency of these effects on distinct coastal ecosystems located within the same landscape. Managing the pervasive impacts of urbanisation on animal assemblages and ecological functions will, therefore, require targeted approaches that address the underlying impacts of urbanisation across multiple coastal ecosystems. [ABSTRACT FROM AUTHOR]

ABSTRACT Understanding how low salinity gradients (0‰–5‰) influence fish life cycles is critical for clarifying principles of fish assemblage formation in estuarine ecosystems. This study is intended to provide a foundation for predicting changes in fish populations amidst ongoing surface salinity decreases in the Baltic Sea. In the Neva River Estuary, differences in fish diversity and distribution between fish assemblages in freshwater and oligohaline areas were assessed using beach seine and multi‐mesh gillnet surveys. The use of multiple sampling gears greatly enhanced understanding of fish distribution across salinity gradients. Fish assemblages were analysed depending on the different areas of the estuary, seasons of sampling, salinity and confounding environmental variables such as water temperature and depth. Salinity was the major influencing factor for the surf zone fish assemblages and a season of sampling was the main factor for coastal assemblages of larger fish studied with the gillnets. Fish assemblages in the surf zone exhibited significant but gradual changes in freshwater and marine‐estuarine fish occurrence and abundance along the critical oligohaline barrier ‘δ‐horohalinicum’ (0.5‰–1.9‰). Although freshwater species showed high occurrence and abundance throughout the estuary, their juveniles were less abundant in the oligohaline surf zone with salinity ≥ 2‰, where small‐size marine‐estuarine and euryhaline species predominated. Coastal multi‐mesh gillnet catches showed remarkable similarity between assemblages of larger fish in freshwater and oligohaline areas. Differences in species richness and diversity indices were not pronounced throughout the salinity gradient; the decline in freshwater species was offset by an increase in marine‐estuarine and euryhaline species. [ABSTRACT FROM AUTHOR]

In the surfzone, breaking‐wave generated eddies and vortices transport material along the coast and offshore to the continental shelf, providing a pathway from land to the ocean. Here, surfzone vorticity is investigated with unique field observations obtained during a wide range of wave and bathymetric conditions on an Atlantic Ocean beach. Small spatial‐scale [O(10 m)] vorticity estimated with a 5 m diameter ring of 14 current meters deployed in ∼2 m water depth increased as the directional spread of the wave field increased. Large spatial‐scale [O(100 m)] vorticity calculated from remote sensing estimates of currents across the surfzone along 200 m of the shoreline increased as alongshore bathymetric variability (channels, bars, bumps, holes) increased. For all bathymetric conditions, large‐scale vorticity in the inner surfzone was more energetic than in the outer surfzone. Plain Language Summary: Circular, rotating flow features, such as eddies, swirls, and vortices mix and disperse material throughout the ocean. Here, circular flow features that can transport sediments, pollutants, and biota from the shore to the continental shelf were investigated using field observations from a 5 m diameter ring of current meters in 2 m depth and from tracking naturally occurring ocean foam visible in optical images of the surfzone (where waves break) spanning 200 m of the coast. The observations show that small‐scale flow patterns become more energetic as ocean waves arrive from a wider range of directions and that large‐scale flow features become more energetic as the seafloor becomes more nonuniform (including holes and channels). Key Points: Surfzone vorticity is estimated for the first time with unique field observations within, across, and along the surfzoneIn situ observations show that small‐scale vorticity injected by breaking waves increases with wave directional spreadRemotely sensed observations show large‐spatial scale vorticity increases as bathymetry becomes more alongshore inhomogeneous [ABSTRACT FROM AUTHOR]

Sandy beaches and their surf zones characterise many of the world's open coastlines. They are important breeding, nursery and feeding areas for many species of fish. Despite the commonness and importance of sandy beach surf zones, the dynamics, space occupancy and diversity patterns of residing fish is in many places poorly understood. The aim of this study was to (1) characterise the fish community structure in 11 simple structured sandy surf zones of the northern Baltic Sea and (2) relate variation in fish abundance and community structure to a set of chosen abiotic variables. Using beach seine, weekly or biweekly sampling was conducted at fixed sites at 10 occasions throughout a summer season. A total of 60,006 fish individuals belonging to 20 species were recorded. Changes in abundance and community structure were mainly driven by the variation of only five species reflecting species‐specific recruitment patterns and different spatial responses to abiotic variables. Dominating groups were Gasterosteidae, Ammodytidae and Gobiidae that together formed 86% of the total adult fish catches. Larval numbers were completely dominated by Gobiidae. Multivariate analyses indicated species‐specific responses to measured environmental variables, most important being a combination of wave exposure, beach slope, bottom roughness, and temperature. The present study shows that changes in fish abundance on simple structured sandy sublittoral beaches in the northern Baltic Sea are large over the course of a breeding season. It also reveals that variation in adult and juvenile fish are driven by a set of abiotic factors that influence on the fish assemblage structure through mainly species‐specific, rather than through generic responses. Unravelling the degree to which the sandy shore fish community vary in the northern Baltic Sea will help in managing coastal environments that are increasingly being threatened by many anthropogenic stressors. [ABSTRACT FROM AUTHOR]

ABSTRACT Sandy beaches and their surf zones characterise many of the world's open coastlines. They are important breeding, nursery and feeding areas for many species of fish. Despite the commonness and importance of sandy beach surf zones, the dynamics, space occupancy and diversity patterns of residing fish is in many places poorly understood. The aim of this study was to (1) characterise the fish community structure in 11 simple structured sandy surf zones of the northern Baltic Sea and (2) relate variation in fish abundance and community structure to a set of chosen abiotic variables. Using beach seine, weekly or biweekly sampling was conducted at fixed sites at 10 occasions throughout a summer season. A total of 60,006 fish individuals belonging to 20 species were recorded. Changes in abundance and community structure were mainly driven by the variation of only five species reflecting species‐specific recruitment patterns and different spatial responses to abiotic variables. Dominating groups were Gasterosteidae, Ammodytidae and Gobiidae that together formed 86% of the total adult fish catches. Larval numbers were completely dominated by Gobiidae. Multivariate analyses indicated species‐specific responses to measured environmental variables, most important being a combination of wave exposure, beach slope, bottom roughness, and temperature. The present study shows that changes in fish abundance on simple structured sandy sublittoral beaches in the northern Baltic Sea are large over the course of a breeding season. It also reveals that variation in adult and juvenile fish are driven by a set of abiotic factors that influence on the fish assemblage structure through mainly species‐specific, rather than through generic responses. Unravelling the degree to which the sandy shore fish community vary in the northern Baltic Sea will help in managing coastal environments that are increasingly being threatened by many anthropogenic stressors.

Abstract In the surfzone, breaking‐wave generated eddies and vortices transport material along the coast and offshore to the continental shelf, providing a pathway from land to the ocean. Here, surfzone vorticity is investigated with unique field observations obtained during a wide range of wave and bathymetric conditions on an Atlantic Ocean beach. Small spatial‐scale [O(10 m)] vorticity estimated with a 5 m diameter ring of 14 current meters deployed in ∼2 m water depth increased as the directional spread of the wave field increased. Large spatial‐scale [O(100 m)] vorticity calculated from remote sensing estimates of currents across the surfzone along 200 m of the shoreline increased as alongshore bathymetric variability (channels, bars, bumps, holes) increased. For all bathymetric conditions, large‐scale vorticity in the inner surfzone was more energetic than in the outer surfzone.

The flagfin mojarra (Eucinostomus currani) is an important subsistence fishery resource in local Ecuadorian markets; however, very little is known about the early life history and reproductive biology of this species. In 2016 and 2017, E. currani larvae were collected at 3 sandy beaches in the Gulf of Guayaquil, Ecuador, and identified using DNA barcoding. Standard lengths ranged from 4.00--15.78 mm. We also collected otoliths to better understand the early life history of E. currani. Otoliths were used to estimate the age, population growth rate (±SE), hatch dates, and reproductive period. On average, the fish were 16.5 ± 4.5 days old, while the average growth rate was 0.70 ± 0.05 and 0.22 ± 0.16 mm per day in March and May, respectively. In the Gulf of Guayaquil, most hatch dates and the presumed reproductive activity of E. currani occurred during the wet season (December--April) when warmer water prevailed. To our knowledge, this is the first study to estimate the hatch dates and larval growth rate for a species of the family Gerreidae in the Pacific Ocean. [ABSTRACT FROM AUTHOR]

The effects of surf zone eddy generated by alongshore currents on the deformation and transport of dye are still poorly understood, and related tracer release experiments are lacking. Therefore, a tracer release laboratory experiment was conducted under monochromatic, unidirectional incident waves with a large incident angle (30°) on a plane beach with a 1:100 slope in a large wave basin. A charge-coupled device suspended above the basin recorded the dye patch image. The evolution of eddy dye patch was observed and the transport and diffusion were analyzed based on the collected images. Subsequently, a linear instability numerical model was adopted to calculate the perturbation velocity field at the initial stage. The observation and image processing results show that surf zone eddy patches occurred and were separated from the original dye patches. Our numerical analysis results demonstrate that the structure of the perturbation velocity field is consistent with the experimental observations, and that the ejection of eddy patches shoreward or offshore may be ascribed to the double vortex. [ABSTRACT FROM AUTHOR]

The flagfin mojarra (Eucinostomus currani) is an important subsistence fishery resource in local Ecuadorian markets; however, very little is known about the early life history and reproductive biology of this species. In 2016 and 2017, E. currani larvae were collected at 3 sandy beaches in the Gulf of Guayaquil, Ecuador, and identified using DNA barcoding. Standard lengths ranged from 4.00–15.78 mm. We also collected otoliths to better understand the early life history of E. currani. Otoliths were used to estimate the age, population growth rate (±SE), hatch dates, and reproductive period. On average, the fish were 16.5 ± 4.5 days old, while the average growth rate was 0.70 ± 0.05 and 0.22 ± 0.16 mm per day in March and May, respectively. In the Gulf of Guayaquil, most hatch dates and the presumed reproductive activity of E. currani occurred during the wet season (December–April) when warmer water prevailed. To our knowledge, this is the first study to estimate the hatch dates and larval growth rate for a species of the family Gerreidae in the Pacific Ocean.

This paper presents new data from large-scale wave flume experiments. It shows the beach profile evolution and sediment transport for two different bed slopes (1:15 and 1:25), and three irregular high-energy erosive wave conditions and one low-energy accretive wave condition. The bulk cross-shore net sediment transport was investigated for the total active profile and for the surf and swash zone separately. It is shown that the steep slope is morphologically more active than the gentle slope, with faster and more pronounced morphological changes and larger sediment transport rates. For both slopes, the total and surf zone net sediment transport were offshore-directed for erosive waves and onshore-directed for the accretive wave condition. However, the net swash zone transport for the erosive wave conditions was offshore-directed for the steep slope and onshore-directed for the gentle slope. The direction and magnitude of the total and surf zone sediment transport correlate well with the slope-corrected Dean criterion with increasing offshore-directed sediment transport (erosion) observed for increasing wave energy and bed slope. This relation does not hold for the swash zone sediment transport along the gentle slope, suggesting that swash zone sediment transport processes are not well captured when using a simple predictor such as the (modified) Dean number. Differences in sediment transport in the swash for the different slopes are likely influenced by differences in incoming wave energy, wave–swash interactions and the relative importance of long- and short-waves. [ABSTRACT FROM AUTHOR]

The change in the shoreline greatly influences the coastal developments such as maritime trade, fishing activities, coastal transport, and tourism. Due to the requirements of vast developments along the coast near major habitat zones, such as the Karaikal coast along the east coast of India, it is essential to understand the longshore sediment transport (LST) movement to plan for any coastal systems to protrude. A detailed LST estimate has been made with the predicted wave climate using the wind-wave model, WAM. The wave characteristics are compared with the field measurements off the coast considered herein. The LST rates computed using five different sediment transport formulae and the method of integrating the distribution of sediment transport rates within the surf zone have been computed to understand the variations of the estimate in each method. Although the predominant direction of sediment movement is towards the north, there is a seasonal variability of LST based on the prevailing monsoon wind direction. Monitoring and analysis of the LST are important as it is required in designing coastal structures. [ABSTRACT FROM AUTHOR]

Sandy beaches and their associated surf zones are the most common type of open shoreline, with significant ecological and socio‐economic importance. In this study, we explored the seasonal fluctuations of the surf zone holo‐ and meroplankton communities to understand the underlying environmental variables driving the temporal dynamics of each community. We also defined a surf‐zooplankton community on a temperate sandy beach (Monte Hermoso, Argentina) and related the organisms to those reported in a nearby estuary for a better understanding of the connection between adjacent coastal ecosystems. Holoplankton was very abundant (13.52–11070.4 ind m−3) and showed a strong seasonality, mainly related to the specific pattern of the two most abundant species: Acartia tonsa (>autumn) and Paracalanus parvus (>winter). This community was affected by seasonal changes in water temperature and salinity and variations in the velocity of currents, which showed that hydrodynamic forces were more significant on a short‐term time scale than seasonal ones. Meroplankton abundances (1.3–48.05 ind m−3) were significantly lower than those recorded for the holoplankton and were mainly dominated by Medusae and larvae of Bivalvia and Decapoda. This fraction also showed a clear seasonal pattern (>abundances in summer), primarily related to the seasonal changes in temperature. The abundances of the main surf‐zooplanktonic taxa were high and constant, emphasizing the importance of these waters as habitats for well‐established communities rather than being used as a transient area. Consequently, we proposed a "specific" surf‐zooplankton community for a temperate sandy beach, considering resident and non‐resident taxa. Finally, the comparison of the surf and estuarine communities indicated a faunal relationship between seascapes, highlighting the ecological role of coastal waters in planktonic life. [ABSTRACT FROM AUTHOR]

Field measurements of longshore sediment transport have been performed in the surf zone along Denu Beach, located in the Volta Region of Ghana, West Africa. This study consisted of measuring sediment transport rates by the deployment of modified versions of Kraus streamer traps on a cross-shore distance, which was about half the average surf zone width. In addition to the measured transport rates, data on waves, longshore currents, and other morphological parameters were collected with simple and low-cost instrumentation. In total, about 22 datasets were obtained through several days of data collection spanning a period of 5 months. Mathematical formulae proposed by CERC (1984), Kamphuis (1991), and the new van Rijn (2014) were used to compute theoretical transports for the entire surf zone, which were validated by measured data. Applying the CERC equation with a K-value of 0.39, the theoretical transports were about one order of magnitude higher than the measured rates. The rates computed by the Kamphuis formula were slightly higher than those yielded by the van Rijn equation. They produced values that were, on average, about 3.5 and 2.9 times higher than the measured rates, respectively. This study then confirmed the capabilities of both the Kamphuis and van Rijn equations to provide closer estimates of longshore sediment transport on Denu Beach. It especially sheds light on the new van Rijn formula, which has not been used extensively in LST quantification across the world. We, therefore, concluded that both the Kamphuis and van Rijn equations could be particularly useful to local engineers in the prediction of LST prior to the design of coastal protection structures. Further long-term studies employing available cutting-edge technologies were also recommended to provide more information on longshore transport not only in Ghana but also in the entire Gulf of Guinea and for the establishment of a reliable sediment budget for the country and the entire region. [ABSTRACT FROM AUTHOR]

Dispersion of dissolved contaminants introduced at various locations within and just outside the surf zone are investigated. It is shown that the Longuet-Higgins model of surf-zone hydrodynamics adequately describes the distribution of longshore currents measured at the laboratory scale. Relations are derived between the longitudinal and transverse dispersion coefficients and the influencing parameters. The maximum longitudinal dispersion coefficients are associated with tracer releases near the breaker line, and longitudinal dispersion coefficients generally increase with travel time for distances up to at least 10 surf-zone widths. In contrast, transverse dispersion coefficients remain relatively constant for increasing travel time. The longitudinal and transverse dispersion coefficients can be significantly influenced by assumed values of local turbulent diffusion and cross-shore shear dispersion.

Various physical mechanisms are implicated in the transport of zooplankton to the outer edge of the surf zone, which is the final barrier before reaching the adult habitat of many meroplanktonic organisms. To explore these physical mechanisms, we measured the abundance of zooplankton in the surf zone hourly for 3 consecutive days during strong internal tidal forcing while concurrently measuring winds, currents, and seawater temperature. Strong temperature changes in the water column that were associated with internal tidal bores, as well as onshore coastal winds, coincided with peaks in abundance of barnacle cyprids, gastropods, and bryozoan larvae in the surf zone. This study supports the hypothesis that both internal tidal bores and onshore winds can accumulate zooplankton nearshore, and that these transport mechanisms may act in concert.

Sandbars are ubiquitous morphologic features found in the nearshore environment throughout the world, yet predictive capabilities of their evolution remain limited. In order to provide new insights on the relevant processes controlling sandbar morphodynamics, this study uses a 41‐year record of 637 monthly cross‐shore profiles from Duck, North Carolina, USA, to derive complex empirical orthogonal functions representative of the two dominant modes of sandbar migrations: offshore and onshore propagation. Interference of these two modes produces commonly observed sandbar states. While mild wave energies are traditionally assumed to drive onshore sandbar migration, the offshore mode is repeatedly seen to dominate sandbar migration in mild wave seasons following anomalously high late‐winter wave energy and when the inherited morphology is composed of a single bar or terrace, as opposed to a more common two‐bar state. A data‐derived conceptual model is presented synthesizing the effect of antecedent morphology and wave climate chronology on interannual trends in net offshore sandbar migration. Plain Language Summary: Sandbars commonly exist in shallow water just offshore of sandy coastal beaches. These features are thought to play an important role in protecting the beach from storm waves, but unfortunately there is limited skill in predicting how these sandbars form and move. An unparalleled 41‐year, monthly data set of nearshore sandbar behavior is used in this work to identify a repetitive pattern where emergence of new sandbars in the nearshore occurs when offshore migration occurs during mild wave seasons, which is contradictory to traditional conceptual models for nearshore morphology evolution. A new conceptual map is derived from the data that identifies common sandbar states and the migration direction that produces changes from one state to another, specifically highlighting that sandbar migration direction at the seasonal to yearly scale is strongly dependent on winter wave climates and the sandbar state at the beginning of mild wave seasons each spring. Key Points: Sandbar migrations in on‐ and offshore directions expressed as propagating modes derived from 41 years of surveysOffshore migrations are observed during mild wave conditions when a single‐bar or terraced beach profile is presentThe relative timing of large wave energy prior to extended periods of mild conditions enables offshore migrations [ABSTRACT FROM AUTHOR]

This study focuses on the numerical investigation of the 3D hydrodynamic processes of coastal zones such as wave breaking, wave-induced currents, and sediment transport, using the multiphase, interFoam solver of OpenFOAM® (a state-of-the-art, open-source CFD numerical tool). The numerical scheme is suitably framed by initial conditions of wave propagation and absorption using waves2Foam wave library. The turbulence closure problem is handled using a buoyancy modified k–ω SST model. In order to predict the sediment transport rate due to waves and currents (bed load, sheet flow, and suspended load over ripples), a transport-rate formula involving unsteady aspects of the sand transport phenomenon is implemented. For the suspended load in the surf zone, the Bailard formula is adopted after considering that the dissipation mechanism is the wave breaking. Results concerning wave height, longshore current, turbulence kinetic energy, and sediment transport are compared against experimental data and semi-empirical expressions. [ABSTRACT FROM AUTHOR]

Lee, J. and Hong, S., 2023. Morphodynamics of rip current systems at Haeundae Beach, Korea. Journal of Coastal Research, 39(1), 199–206. Charlotte (North Carolina), ISSN 0749-0208. Rip current generation and beach morphodynamics were measured for about 60 days at Haeundae Beach, Busan, Korea, using various instruments comprising co-located velocity and pressure sensors, ADCPs, and kinematic GPS surveys. Rip currents are narrow currents initiated close to the shoreline that flow strongly in a seaward direction through the surf zone and beyond. It is generally accepted that rip currents arise mostly from the variation of wave height alongshore attritutable to wave refraction over inhomogeneous bathymetry. Field measurement was performed to clarify the generation mechanism of rip currents at Haeundae Beach, Korea. The creation and destruction of sandbars could be identified clearly using data from a photogrammetric survey taken from the roof of a high building during the summer season. In this study, a surf-zone depth survey was performed periodically using Network Real-Time Kinematic GPS, a device that can provide a detailed topographic survey of the surf-zone region. Using these data, we perform a correlation analysis between rip current generation and surf-zone morphological variation. [ABSTRACT FROM AUTHOR]

Investigating trophic linkages sustaining consumers is crucial to understanding their functional ecological role in communities and ecosystems. In this work, we combined stomach content (SCA) and stable isotope (SIA) analyses to investigate the trophic ecology of the Plata pompano Trachinotus marginatus during a critical phase of its life cycle along a subtropical sandy beach. This species is a conspicuous component of the southwestern Atlantic coast and commonly targeted by coastal fisheries. The diet was described using SCA, whereas the relative importance of food sources sustaining juveniles, as well their food niche structure and trophic position (TP), were evaluated using SIA. Juveniles consumed mainly crustaceans like the hippid crab Emerita brasiliensis , although other invertebrates (annelids, insects, molluscs) and fishes (including cannibalism) were also recorded. Although microcrustaceans dominated the diet, SIA showed that more palatable preys without carapaces or shells, like fishes and annelids, were the most assimilated preys in the muscle tissue of juvenile T. marginatus. There were marked changes in their isotopic niches (SEAc) and TP across ontogeny. SEAc ranged from 1.41‰2 for smaller individuals (0–40 TL mm) to 0.3‰2 for larger individuals (>80 TL mm). TP ranged from 3.1 (95% CI 2.7–3.6) for smaller to 4.5 (95% CI 3.9–5.1) for larger individuals. SIA suggest that juvenile T. marginatus derived most of their primary nutrients from a planktonic food web and, to a lesser extent, from a benthic pathway. Future studies are needed to better understand its functional role in food web of surf-zone ecosystems. [ABSTRACT FROM AUTHOR]

This study investigates the combined effect of the breaking and energy dissipation of water waves by variable bottoms across the surf zone. The shoreline is set up as a partially reflecting vertical wall in the solution technique, with shelves between the steps that approximate the geometric profile of the varied bottom over the surf zone. The eigenfunctions over the shelves are matched on the connecting step using the conservations of mass and momentum. The impacts of breaking and energy dissipation are implemented in the proposed eigenfunction matching method using the energy-dissipation factors, which are modeled by empirical formulas. The proposed model is validated by comparing its results with the experimental data available in the literature. Some benchmark results of wave scattering by a rectangular breakwater near a partially reflecting vertical wall are provided and discussed. In addition, wave breaking and dissipation in the proposed model using different empirical formulas are discussed. [ABSTRACT FROM AUTHOR]

Reversals in wave-generated longshore currents in surf zones occur at different temporal and spatial scales. Along coastlines with tidal channel openings with well-developed mouth bars or ebb-tidal deltas, the reversal mechanism is often attributed to the mouth bar – induced refraction of the shoaling waves. This reversal mechanism is characterized by convergence of longshore currents from the adjoining surf zones at the mouth of the tidal channel. Simultaneous half-hourly monitoring of wave-generated longshore currents over 50 successive (daylight) semi-diurnal tidal cycles in beach surf zones adjoining the Qua Iboe River estuary, S.E coast of Nigeria showed the above reversal pattern during flooding stage only. The converse pattern, where the surf zone longshore currents diverged away from the mouth of the estuary, was observed during ebbing stage. Both surf zones showed flow direction inversion with respect to each other, with velocity vector correlation coefficient r > − 0.8 in over 80 % of the data set. Instances of comparable flow direction (<10 %) were also recorded. Tidal processes are implicated in the documented results. Direction-averaged longshore current velocities, typically in the 15–60 cm/s range, attained highest values in both surf zones at about spring tide phase. Also, tidal cycle-residual longshore current maximum and minimum velocities occurred close to spring and neap tide, respectively. Only 30 % of the residual velocities were eastward directed in the up-drift surf zone as against 80 % in the down-drift counterpart. Given the prevailing southwesterly waves, the present results negate the assertion that reversal in longshore current direction in this offset shoreline setting is exclusively a consequence of wave refraction by mouth bar morphology. The reversing pattern of the longshore currents over a tidal cycle is well explained by incorporating interacting effects of shoaling waves with tide-induced oscillations in water level as well as the estuarine flow. • Wave-generated longshore current direction reversal occurred at tidal frequencies • Wave refraction by estuarine mouth bar as sole mechanism for flow reversal was unlikely • Impact of tidal processes on flow pattern differed with tidal stage and lunar phase • Pressure gradient can drive flow in direction opposite to breaker angle dictated. [ABSTRACT FROM AUTHOR]

This paper presents new data from large-scale wave flume experiments. It shows the beach profile evolution and sediment transport for two different bed slopes (1:15 and 1:25), and three irregular high-energy erosive wave conditions and one low-energy accretive wave condition. The bulk cross-shore net sediment transport was investigated for the total active profile and for the surf and swash zone separately. It is shown that the steep slope is morphologically more active than the gentle slope, with faster and more pronounced morphological changes and larger sediment transport rates. For both slopes, the total and surf zone net sediment transport were offshore-directed for erosive waves and onshore-directed for the accretive wave condition. However, the net swash zone transport for the erosive wave conditions was offshore-directed for the steep slope and onshore-directed for the gentle slope. The direction and magnitude of the total and surf zone sediment transport correlate well with the slope-corrected Dean criterion with increasing offshore-directed sediment transport (erosion) observed for increasing wave energy and bed slope. This relation does not hold for the swash zone sediment transport along the gentle slope, suggesting that swash zone sediment transport processes are not well captured when using a simple predictor such as the (modified) Dean number. Differences in sediment transport in the swash for the different slopes are likely influenced by differences in incoming wave energy, wave–swash interactions and the relative importance of long- and short-waves.

Abstract Sandbars are ubiquitous morphologic features found in the nearshore environment throughout the world, yet predictive capabilities of their evolution remain limited. In order to provide new insights on the relevant processes controlling sandbar morphodynamics, this study uses a 41‐year record of 637 monthly cross‐shore profiles from Duck, North Carolina, USA, to derive complex empirical orthogonal functions representative of the two dominant modes of sandbar migrations: offshore and onshore propagation. Interference of these two modes produces commonly observed sandbar states. While mild wave energies are traditionally assumed to drive onshore sandbar migration, the offshore mode is repeatedly seen to dominate sandbar migration in mild wave seasons following anomalously high late‐winter wave energy and when the inherited morphology is composed of a single bar or terrace, as opposed to a more common two‐bar state. A data‐derived conceptual model is presented synthesizing the effect of antecedent morphology and wave climate chronology on interannual trends in net offshore sandbar migration.

We investigated whether cross-shore distributions of coastal phytoplankton to the surf zone are controlled by hydrodynamics and their biological characteristics. Data from a rip-channeled beach indicate that concentrations of phytoplankton are higher in the surf zone than offshore. To examine how phytoplankton is transported toward the shore, we used a coupled biophysical model, comprised of a 3D physical model of coastal dynamics and an individual-based model (IBM) for tracking phytoplankton on the rip-channeled beach. Waves and wind in the biophysical model were parameterized by the conditions during the sampling period. Previous studies indicated that growth rates of phytoplankton can be enhanced by high turbulence, which might contribute to high phytoplankton concentration in the surf zone. Some numerical and laboratory works showed that turbulence can also increase the downward velocity of phytoplankton, which could be carried by onshore bottom currents and remain in the surf zone. Furthermore, we adapted the IBM with the theoretical model of diurnal vertical migration (DVM) for phytoplankton. The theoretical DVM works as follows: in the morning, phytoplankton cells adhere to air bubbles and stay at the surface and close to the shore in the daytime because onshore wind and surface current direction is usually onshore; in the late afternoon, the cells switch their attachment from air bubbles to sand grains and sink to the bottom where the water flow is normally onshore at night. Finally, depth-varying growth of phytoplankton was also incorporated into the DVM module. Simulations using neutral passive particles do not give the expected results of observed patterns. All tested mechanisms, i.e., wind- and wave-driven currents, rip-current circulation, turbulence-driven growth and sinking, DVM, and depth-varying growth, enhanced onshore phytoplankton migration and cell concentrations in the surf zone, indicating that both biological traits and physical factors can be essential to phytoplankton cross-shore transport and spatial variability. Our model is open to be modified and re-parameterized, followed by further analysis and validation, so that it can be more adequate for ecological assessment of coastal areas.

The Intermittent Upwelling Hypothesis (IUH) posits that subsidies of larvae and phytoplankton to intertidal communities should vary unimodally along a gradient of upwelling from persistent upwelling to persistent downwelling with most subsidies occurring where upwelling is of intermediate strength and intermittent. Furthermore, the hypothesis states that larvae and phytoplankton are transported far offshore by strong, persistent upwelling and fail to subsidize nearshore communities, whereas weak upwelling or downwelling reduces nutrients for phytoplankton production limiting food for larvae and nearshore communities. We review studies conducted at sea and onshore and reanalyze published data to test the IUH and evaluate alternative hypotheses. To test the hypothesis, we examine five predictions that must hold if the IUH is true. (1) Larvae should inhabit the surface Ekman layer where they are transported offshore during upwelling. Larvae of many intertidal taxa occur deeper in the water column where currents flow shoreward during upwelling. (2) Larvae of nearshore species should occur farther offshore during upwelling than during relaxation or downwelling. Larvae of many nearshore species remain within several kilometers of shore during both conditions. (3) Larval settlement in intertidal communities should be lower during upwelling than relaxation or downwelling. Daily larval settlement has not observed to be higher during relaxation or downwelling events; settlement has most often been seen to vary with the fortnightly tidal cycle likely due to onshore larval transport by internal tides. (4) Larval settlement and recruitment in intertidal communities should be lower in areas of strong, persistent upwelling than where upwelling is weaker and less persistent. Recruitment of mussels and barnacles to artificial and natural substrates did not vary with the strength of upwelling, but did vary inversely with two measures of desiccation potential, and directly with indicators of surf zone hydrodynamics; larval recruitment was higher where surf zones were more dissipative with rip currents. (5) Phytoplankton subsidies to nearshore communities should be highest where upwelling is moderate and intermittent. Like larval subsidies, phytoplankton subsidies varied spatially with surf zone hydrodynamics rather than upwelling. This reconsideration of the evidence for the IUH finds the hypothesis unsupported.

Plankton are transported onshore, providing subsidies of food and new recruits to surf-zone and intertidal communities. The transport of plankton to the surf zone is influenced by wind, wave, and tidal forcing, and whether they enter the surf zone depends on alongshore variation in surf-zone hydrodynamics caused by the interaction of breaking waves with coastal morphology. Areas with gently sloping shores and wide surf zones typically have orders-of-magnitude-higher concentrations of plankton in the surf zone and dense larval settlement in intertidal communities because of the presence of bathymetric rip currents, which are absent in areas with steep shores and narrow surf zones. These striking differences in subsidies have profound consequences; areas with greater subsidies support more productive surf-zone communities and possibly more productive rocky intertidal communities. Recognition of the importance of spatial subsidies for rocky community dynamics has recently advanced ecological theory, and incorporating surf-zone hydrodynamics would be an especially fruitful line of investigation.

The rehabilitation timing of a damaged rubble mound structure depends on the remaining capacity of the deteriorated structure. A laboratory experiment was conducted in a wave flume to measure the remaining capacity of a low-crested rubble mound inside the surf zone on a sand beach. The formation of a bar and trough feature modified wave conditions at the toe of the structure. Wave transmission over and through the structure increased with lowering of the mound crest. The mound with a double armor layer on smaller core stones was exposed to irregular wave action lasting 22.2 h. Some of the core stone was visible through holes of the thinned armor layer but remained in place. Crest lowering reduced the wave action on the damaged mound. On the other hand, the mound with a single armor layer did not stabilize itself because of core stone removal after 7.8 h. The rubble mound structure was resilient as long as the core stone was protected. [ABSTRACT FROM AUTHOR]

We present here the first study documenting the variability in growth and pigment signature with fluctuating light in a tropical surf-zone (coastal Bay of Bengal) phytoplankton assemblage. In response to an 8.5 times light cut-off for 3 days, 50% of the particulate organic matter (POC)-based growth rate (μ POC d−1) was maintained. Chlorophyll a (Chl a) and light-harvesting pigment (LHP) contents exhibited a reverse trend without increasing POC contents, suggesting that the Chl a -based growth rate can be biased under fluctuating light. Certain commonly occurring diatoms like Skeletonema , Leptocylindrus and Chaetoceros exhibited high light preference, whereas another diatom Thalassiosira proliferated at low light. Phytoplankton pigment signature was also monitored on an hourly basis over a day and the lowest LHP contents were associated with the highest photon flux densities, whereas the highest values were noticed during morning and evening hours. The ratio between photo-protective to LHP remained < 0.5, indicating that LHP contents were always greater than photo-protective pigment values and the cells were not severely light stressed. Iron (Fe) supplementation did not alter POC accumulation; photo-protective to LHP ratios also indicated Fe adequacy in this coastal water and the observed variability in the pigment signature was entirely attributed to variable light. [ABSTRACT FROM AUTHOR]

Field measurements of longshore sediment transport have been performed in the surf zone along Denu Beach, located in the Volta Region of Ghana, West Africa. This study consisted of measuring sediment transport rates by the deployment of modified versions of Kraus streamer traps on a cross-shore distance, which was about half the average surf zone width. In addition to the measured transport rates, data on waves, longshore currents, and other morphological parameters were collected with simple and low-cost instrumentation. In total, about 22 datasets were obtained through several days of data collection spanning a period of 5 months. Mathematical formulae proposed by CERC (1984), Kamphuis (1991), and the new van Rijn (2014) were used to compute theoretical transports for the entire surf zone, which were validated by measured data. Applying the CERC equation with a K-value of 0.39, the theoretical transports were about one order of magnitude higher than the measured rates. The rates computed by the Kamphuis formula were slightly higher than those yielded by the van Rijn equation. They produced values that were, on average, about 3.5 and 2.9 times higher than the measured rates, respectively. This study then confirmed the capabilities of both the Kamphuis and van Rijn equations to provide closer estimates of longshore sediment transport on Denu Beach. It especially sheds light on the new van Rijn formula, which has not been used extensively in LST quantification across the world. We, therefore, concluded that both the Kamphuis and van Rijn equations could be particularly useful to local engineers in the prediction of LST prior to the design of coastal protection structures. Further long-term studies employing available cutting-edge technologies were also recommended to provide more information on longshore transport not only in Ghana but also in the entire Gulf of Guinea and for the establishment of a reliable sediment budget for the country and the entire region.

Simple Summary: Prior to the invasion and spread of Dreissena mussels in the late 1980s, the nearshore waters of the Laurentian Great Lakes were home to diverse assemblages of native aquatic insects, including the net-spinning caddisfly Hydropsyche alternans, which occurred in rocky surf-exposed habitat throughout the system from Lake Superior downstream to Lake Ontario. These surf zone caddisflies are still abundant in the largely Dreissena-free waters of Lake Superior where the present study was conducted. They have not been reported in the lakes below Lake Superior for decades, and are presumed to have been extirpated from Dreissena-infested habitats. The ecological profile presented here documents the life history of H. alternans in Lake Superior, and reveals details of its feeding biology that shed light on the roles that surf zone net-spinners play in the native nearshore food webs of the Great Lakes. The H. alternans life history in Lake Superior begins in mid-summer shortly after oviposition, which features females swimming to surf-exposed lake bottom substrates. Larval development takes approximately 10 months, but most of it occurs during their first 100 days. Adult emergence is broadly synchronous, with large numbers present from the summer solstice through mid-July. Gut content analyses showed that larvae opportunistically feed on algal, animal, and detrital material of aquatic and terrestrial origin. δ13C and δ15N stable isotope data indicate that they function as omnivores that link coastal, nearshore, and pelagic food webs. These energetic links, and the very existence of surf zone insect assemblages in the Great Lakes, depend on the Dreissena populations in Lake Superior remaining relatively small and isolated. We studied the life history, diet, and trophic ecology of Hydropsyche alternans in four rocky sites located along the south-central coast of Lake Superior. The H. alternans life history and broad trophic niche space were similar to those of its riverine relatives. Quantitative sampling over the course of one ice-free season revealed that most individuals lived univoltine life histories that featured early to mid-summer mating, and oviposition and rapid growth and development through summer into fall. Most individuals overwintered as ultimate or penultimate larval instars. Pupation followed ice-out in the spring. Gut content sampling and δ13C and δ15N stable isotope analyses indicated that the typical larval diet is a mix of benthic, pelagic, and terrestrial food resources, including diatoms, small arthropods, sloughed periphyton, and in one site, fugal hyphae apparently of foredune origin. As a suspension-feeding omnivore that relies on waves and currents to deliver food to its nets, H. alternans larvae form energetic links between coastal, nearshore, and offshore food webs. These connections have been lost throughout the lower Laurentian Great Lakes as a consequence of the invasion and spread of Dreissena mussels. [ABSTRACT FROM AUTHOR]

The publication highlights a number of the problem aspects of the geoecosystem components pollution of the Black Sea Ukrainian sector by plastic waste and microplastics. On the field research and literature sources processing basis a question review was carried out and certain analytical generalizations were received. Emphasis is placed on the insufficient problem study degree of the shelf Ukrainian part pollution by synthetic and artificial polymers in comparison with similar areas of other Black Sea countries. This determines the need for initial systematization and identification of current research areas on this issue, and the field observations implementation and an information base creation. The conducted field works results in the area of Yuzhne city beach are presented, the main purpose of which was to study the peculiarities of plastic waste and microplastics distribution in current sand deposits and sea suspension of active recreation areas. Analysis of the obtained data involving of similar studies results presented in the available literature shows a low level of Yuzhne beach area pollution compared to some parts of the coast within the Mediterranean, North Atlantic, and Bulgarian sector of the Black Sea. The conducted research allowed gaining practical experience, determining a certain arsenal of field research methods and getting a preliminary idea of pollution degree and plastic waste quality composition within Ukraine coastal city popular recreation area. Further problem state analysis, practical field work and the appropriate laboratory base development will increase the reliability of obtaining and processing data on volumes, sources and routes of plastic waste entry into the Black Sea ecosystems, as well as harmonize the processes of obtaining and processing data in accordance with established global methodologies and techniques.

Larvae of intertidal invertebrates need to cross the surf zone to settle in their adult habitat. Onshore transport of invertebrate larvae and detritus at a steep beach was simulated with a biophysical larval tracking model. Hydrodynamic model calculations were performed for 24 h after a 24 h spin-up stage with bathymetry and averaged wave data obtained during the summer of 2011 at Carmel River State Beach, California, and with and without onshore wind. The physical model output was then transferred to a Lagrangian larval tracking model using several types of particles representing larvae. A southward alongshore current controlled particle distribution in the middle and north of the domain. At the southern shore, negatively buoyant particles were trapped by eddies generated between the alongshore current and shore, while positively buoyant particles were carried onshore by wind-driven surface currents. The concentration of modeled detritus in the surf zone was positively correlated with that of negatively buoyant larvae. Additionally, the concentrations of detritus and competent larvae within the surf zone were negatively correlated with wave height, consistent with the observations of the accompanying field study. Some eddies contributed to forming high particle concentration patches by trapping them in the surf zone. More small eddies were generated closer to the shore with smaller waves, leading to high larval and detrital concentration in the surf zone. As waves increased in size, fewer and larger eddies formed, predominantly outside the surf zone, and consequently fewer larvae and detritus particles entered or stayed in the surf zone.

Wave-induced pressure gradients and local accelerations are important interconnected physical mechanisms involving several hydrodynamic and morphodynamic coastal phenomena. Therefore, to provide a reliable and realistic hydrodynamic and morphodynamic simulation, the dependencies among different parameters, such as water level, pressure gradient, local acceleration, and sediment concentration, should be considered. Herein, a copula-based simulation is presented for modeling multivariate parameters and maintaining their statistical characteristics within the surf zone. Archimedean and elliptical copula families are applied to investigate the dependency construction between the parameters in two case studies: one from a field site on the east coast of Japan, and another from a large-scale laboratory barred beach profile. The dependency between variables is evaluated using Kendall’s τ correlation coefficient. The water level, pressure gradient, and local acceleration are shown to be significantly correlated. The correlation coefficients between the variables for the natural beach are lower than the laboratory data. The marginal probabilistic distribution functions and their joint probabilities are estimated to simulate the variables using a copula approach. The performance of the simulations is evaluated via the goodness-of-fit test. The analysis shows that the laboratory data are comparable to the field measurements, implying that the laboratory simulation results can be applied universally to model multivariable joint distributions with similar hydrodynamic conditions.

• Incorporating air bubbles in breaking waves two energy dissipation models are devised. • The fraction of breaking waves concept has been used to develop these models. • Significant wave height & setup are easily computed via these models. • The models were validated using lab experiment data, from authors & collected sources. • Error analyses show M-I outperforms compared to other models with data. The transformation of wave height is of paramount significance in coastal engineering and the design of coastal structures. Considering the influence of air bubbles, this study devised an optimal dissipation model for accurately calculating changes in significant wave height (H m0) and wave set-up for irregular waves undergoing breaking. Existing regular wave breaking models, which consider the effects of air bubbles, were adapted for direct application to irregular waves by deriving novel formulations. The proposed models leverage the probability of the fraction of broken waves. H m0 was computed using the energy balance equation, while the wave set-up was calculated based on the momentum balance equation. A wide range of test scenarios, incorporating diverse scales (small and large) and experimental field data, was considered for validation. One of the proposed models, namely model-I (M-I), particularly demonstrated superior performance, manifesting lower error indices (P20), root-mean-square relative error (RMSRE), and Brier skill score (BSS) values in computing both H m0 and wave set-up. Therefore, utilising M-I is strongly recommended for the precise estimation of H m0 and set-up transformation. [ABSTRACT FROM AUTHOR]

During extreme conditions, the transport of the wave-averaged suspended sediment concentrations in the inner surf zone affects dune erosion. Although large-scale laboratory experiments have provided insight in what drives these sediment concentrations, corresponding field data are lacking. To fill this gap, novel field observations of suspended sediment concentrations are compared to drivers that govern sediment suspension during storm conditions known from literature. A total of 128 time intervals of 20 min are analysed, spread over 10 different high water events with different hydrodynamic conditions. For each time interval, the wave-averaged (i.e. 20 min mean) suspended sediment concentration is computed and compared to three suspension drivers. The studied drivers are (1) bed shear due to near bed velocities that originate from mean currents in combination with wave-induced orbital flow, (2) the horizontal pressure gradients under steep wave fronts that increase the forces on the bed material, and (3) bore-induced turbulence that is generated at the free surface and reaches the bed. The derived bore-induced turbulence generates the greatest correlation with the mean suspended sediment concentrations (r = 0.74, p = 4.47E-23). Samples that deviate from this correlation correspond to time intervals with lower values of derived bore turbulence, less wave energy saturation in the inner surf zone, and stronger mean currents. The correlation with the mean suspended sediment concentrations increases when the shear stress originating from mean currents is used for these time intervals (r = 0.83, p = 1.63E-33). For time intervals during which more energetic conditions persist and the wave energy is saturated in the nearshore, bore turbulence was the dominant mechanism in stirring up sediment. The outcome of this study suggests that, based on the events analysed, dune erosion models may achieve more accurate results if computations of suspended sediment concentrations include a bore-induced turbulence term, or if already included, properly address the relative importance of bore-induced turbulence when compared to bed shearing. • A dune erosion field experiment was conducted to study drivers of wave-averaged suspended sediment concentrations. • The studied drivers are (1) flow-induced bed shearing, (2) horizontal pressure gradients under wave fronts, and (3) bore-induced turbulence. • The variability in bore-induced turbulence generated the greatest correlation with the variability in mean suspended sediment concentrations. • When more energetic conditions persisted and wave energy was saturated in the inner surf zone, bore turbulence appeared the dominant driver. [ABSTRACT FROM AUTHOR]

Surf zones are associated with a shelter area, nursery and feeding for several species of fish. In this study, the dietary habits of three species of fish with demersal habits (Gulf kingcroaker Menticirrhu gracilis, Whitesea catfish Genidens barbus and Barbu Polydacytlus virginicus), were verified in the surf zone area of an active urban beach of Baixada Santista, concerning structure in size, day and night abundances and overlapping diets. A total of 617 fish were analyzed, of which 362 were 194 were G. barbus and 61 were P. virginicus. Stomach contents, represented in Relative Importance Index diagrams, showed that the bivalve Donax gemmula is the most important food item for M. gracilis, scales of Teleostei for G. barbus and Euphausiacea for P. virginicus. In order to evaluate the similarity of the diets, the Macarthur & Levins indices and a cluster analysis with the Bray-Curtis distance were applied revealing that the diet is 44% different between G. barbus and M. gracilis, 5% between G. barbus and P. virginicus and of 84% between M. gracilis and P. virginicus. Anthropogenic waste like plastic, nylon, metal pieces, were only occasionaly observed.

Larvae of intertidal species develop at sea and must return to adult habitats to replenish populations. Similarly, nutrients, detritus and plankton provide important subsidies spurring growth and reproduction of macroalgae and filter-feeding invertebrates that form the foundation of intertidal communities. Together, these factors determine the density and intensity of interactions among community members. We hypothesized that spatial variation in surfzone hydrodynamics affects the delivery of plankton subsidies. We compared entire zooplankton communities inside and outside the surf zone daily while monitoring physical conditions for one month each at two shores with different surfzone characteristics. Opposite cross-shore distributions of larvae and other zooplankters occurred at the two sites: zooplankton was much more abundant inside the mildly sloping dissipative surf zone (DSZ) with rip currents and was more abundant outside the steep reflective surf zone (RSZ). Biophysical numerical simulations demonstrated that zooplankters were concentrated in rip channels of the DSZ and were mostly unable to enter the RSZ, indicating the hydrodynamic processes behind the observed spatial variation of zooplankters in the surf zone. Differences in the concentration of larvae and other zooplankters between the inner shelf and surf zone may be an underappreciated, key determinant of spatial variation in inshore communities.

Multiple intertidal bar (MITB) beach systems comprise a succession of subdued, shore‐parallel sandbars, developed under low‐energy conditions in meso‐ to macrotidal settings. Their relatively stable morphologies over long timescales are commonly attributed to a dynamic equilibrium, driven primarily by seasonal morphodynamics. The seasonal behaviour is, however, poorly understood. The relationship between temporal and spatial hydrodynamic forcing and morphological changes was investigated through monthly differential GPS surveys in Dundrum Bay (Northern Ireland) from April 2019 to March 2020, associated with variations in nearshore wave conditions, simulated using the SWAN wave model. During low‐energy summer conditions, southeast waves helped promote MITB stability and a slight increase in bar crest elevation, with the seaward‐most bar buffering and preserving the inner bar system through wave dissipation. In the winter, a progressive increase in wave energy, and a switch in wave direction (southwest to south), initiated the highest rates of cross‐shore bar migration and a lowering of bar crests. While the seaward‐most bar remained largely submerged, the shoreward‐most bar played a key role in protecting the upper‐beach and/or foredune. Winter conditions also forced a newly observed mesoscale longshore drift involving offshore sediment transport in the southwest and onshore transport in the northeast. Cross‐shore variability in MITB behaviour at seasonal timescales was, however, primarily driven by local hydrodynamic conditions, including variations in wave energy and direction. Conversely, alongshore variability was largely influenced by the complex nearshore bathymetry, headlands and an active ebb delta, all interacting with changing hydrodynamic forcing. These results challenge the seasonal equilibrium model for MITB systems and highlight longer‐term patterns of sediment movement. [ABSTRACT FROM AUTHOR]

Surf zones are associated with a shelter area, nursery and feeding for several species of fish. In this study, the dietary habits of three species of fish with demersal habits (Gulf kingcroaker Menticirrhu gracilis, Whitesea catfish Genidens barbus and Barbu Polydacytlus virginicus), were verified in the surf zone area of an active urban beach of Baixada Santista, concerning structure in size, day and night abundances and overlapping diets. A total of 617 fish were analyzed, of which 362 were 194 were G. barbus and 61 were P. virginicus. Stomach contents, represented in Relative Importance Index diagrams, showed that the bivalve Donax gemmula is the most important food item for M. gracilis, scales of Teleostei for G. barbus and Euphausiacea for P. virginicus. In order to evaluate the similarity of the diets, the Macarthur & Levins indices and a cluster analysis with the Bray-Curtis distance were applied revealing that the diet is 44% different between G. barbus and M. gracilis, 5% between G. barbus and P. virginicus and of 84% between M. gracilis and P. virginicus. Anthropogenic waste like plastic, nylon, metal pieces, were only occasionaly observed. [ABSTRACT FROM AUTHOR]

This study focuses on the numerical investigation of the 3D hydrodynamic processes of coastal zones such as wave breaking, wave-induced currents, and sediment transport, using the multiphase, interFoam solver of OpenFOAM® (a state-of-the-art, open-source CFD numerical tool). The numerical scheme is suitably framed by initial conditions of wave propagation and absorption using waves2Foam wave library. The turbulence closure problem is handled using a buoyancy modified k–ω SST model. In order to predict the sediment transport rate due to waves and currents (bed load, sheet flow, and suspended load over ripples), a transport-rate formula involving unsteady aspects of the sand transport phenomenon is implemented. For the suspended load in the surf zone, the Bailard formula is adopted after considering that the dissipation mechanism is the wave breaking. Results concerning wave height, longshore current, turbulence kinetic energy, and sediment transport are compared against experimental data and semi-empirical expressions.

This study investigates the combined effect of the breaking and energy dissipation of water waves by variable bottoms across the surf zone. The shoreline is set up as a partially reflecting vertical wall in the solution technique, with shelves between the steps that approximate the geometric profile of the varied bottom over the surf zone. The eigenfunctions over the shelves are matched on the connecting step using the conservations of mass and momentum. The impacts of breaking and energy dissipation are implemented in the proposed eigenfunction matching method using the energy-dissipation factors, which are modeled by empirical formulas. The proposed model is validated by comparing its results with the experimental data available in the literature. Some benchmark results of wave scattering by a rectangular breakwater near a partially reflecting vertical wall are provided and discussed. In addition, wave breaking and dissipation in the proposed model using different empirical formulas are discussed.