Estuarine Beach Research Articles

Spatial and temporal patterns of floating litter in shallow habitats: Insights from high-tourism tropical areas in Northeastern Brazil

We investigated the composition, quantity, distribution and potential sources of floating litter in the subtidal zones of tropical beaches. Marine sampling sites were selected based on the presence (protected/sheltered) or absence (non-protected) of reefs. Plastic was the most abundant material, and the presence of floating litter from land-based sources was confirmed, which was likely associated with domestic and tourism-related activities, owing to irregular waste disposal. Marine debris was more abundant during the rainy season, and marine beaches had more floating litter than estuarine beaches. Coastal reefs served as a barrier, impeding the transport of marine litter by coastal currents, explaining the greater abundance of floating litter on protected/sheltered marine beaches. Thus, three mechanisms seemed to drive the amount of floating litter in the subtidal zone of the tropical beaches: 1) the availability of floating litter in the water, 2) coastal hydrodynamics favoring the accumulation of floating litter, and 3) a beach’s capacity to retain floating litter. Our study demonstrates that marine litter is an important pollution source in sensitive areas that play a key role as nurseries for marine life, especially in beaches close to reef formations.

Millennial and contemporary dynamics of the barrier estuary entrance at Moruya, SE Australia

ABSTRACT This study presents optically stimulated luminescence (OSL) dates, sediment coring, historical maps and charts and photography and airborne LiDAR to reconstruct the millennial and contemporary history of the Moruya River entrance. OSL dating reveals small estuarine beaches were active between 7000 and 5000 years ago, when the entrance was far more open than at present. At that time, a large flood-tide delta infilling a wide immature estuary is likely to have existed. Continued progradation of the Bengello barrier to the north, and the inception of the Moruya Heads barrier to the south from 4500 years onward, progressively constricted the river entrance. Several more low-energy estuarine beaches developed behind the Moruya Heads barrier and are dated to ~4400 and ~2800 years ago. Concurrently, the open mud basin of the estuary infilled with fluvial sediment. Following the arrival of Europeans in the region, in the early to the mid-1800s, engineering works were undertaken in stages to train the estuary entrance for navigation and have further constrained the system. OSL dating of beaches formed as a result of this activity concur with the historical accounts. These contemporary changes to the entrance have modified the estuary hydrodynamics and shifted the sediment transport and ecological regime of the lower estuary.

Microplastics associated with stranded macroalgae on an impacted estuarine beach, Rio de Janeiro, Brazil

Microplastics (MPs) are contaminants widely distributed in marine ecosystems. Only few studies approached MP interactions with marine plants, which are considered potential traps for MPs. Here, we determined MPs' densities and types associated with stranded macroalgae on a eutrophic beach in Guanabara Bay. Our results showed that red algae exhibited higher MP densities (1.48 MPs g−1), possibly due to their more branched thalli, than green algae (0.27 MPs g−1). The predominant MP types were blue and white fragments <3 mm in size and polymers were classified as polyethylene and polyvinyl chloride in fragments, and polypropylene in fibers. The higher densities of MPs in algae seemed to be influenced by the inner bay waters. The densities of MPs associated with algae from Guanabara Bay surpassed those reported in other studies. High MPs densities increase the chances that organisms associated with algae entangle or ingest MPs, impacting their health and survival.

Seasonal and anthropogenic influences on bacterioplankton communities: ecological impacts in the coastal waters of Qinhuangdao, Northern China.

Marine bacterioplankton play a crucial role in the cycling of carbon, nitrogen, and phosphorus in coastal waters. And the impact of environmental factors on bacterial community structure and ecological functions is a dynamic ongoing process. To systematically assess the relationship between environmental changes and bacterioplankton communities, this study delved into the spatiotemporal distribution and predicted metabolic characteristics of bacterioplankton communities at two estuarine beaches in Northern China. Coastal water samples were collected regularly in spring, summer, and autumn, and were analyzed in combination with environmental parameters and bacterioplankton community. Results indicated significant seasonal variations in bacterioplankton communities as Bacteroidetes and Actinobacteria were enriched in spring, Cyanobacteria proliferated in summer. While Pseudomonadota and microorganisms associated with organic matter decomposition prevailed in autumn, closely linked to seasonal variation of temperature, light and nutrients such as nitrogen and phosphorus. Particularly in summer, increased tourism activities and riverine inputs significantly raised nutrient levels, promoting the proliferation of specific photosynthetic microorganisms, potentially linked to the occurrence of phytoplankton blooms. Spearman correlation analysis further revealed significant correlations between bacterioplankton communities and environmental factors such as salinity, chlorophyll a, and total dissolved phosphorus (TDP). Additionally, the metabolic features of the spring bacterioplankton community were primarily characterized by enhanced activities in the prokaryotic carbon fixation pathways, reflecting rapid adaptation to increased light and temperature, as well as significant contributions to primary productivity. In summer, the bacterial communities were involved in enhanced glycolysis and biosynthetic pathways, reflecting high energy metabolism and responses to increased light and biomass. In autumn, microorganisms adapted to the accelerated decomposition of organic matter and the seasonal changes in environmental conditions through enhanced amino acid metabolism and material cycling pathways. These findings demonstrate that seasonal changes and human activities significantly influence the structure and function of bacterioplankton communities by altering nutrient dynamics and physical environmental conditions. This study provides important scientific insights into the marine biological responses under global change.

New species and new records of aquatic asexual ascomycetes from estuarine beaches of the Brazilian Amazon

ABSTRACT Estuaries are habitats characterised by high biological productivity; however, fungal biodiversity in these ecosystems remains understudied. During an investigation of asexual ascomycetes associated with decaying twigs in the intertidal zone of fluvial beaches on Mosqueiro Island, Pará, Brazil, three new species have been proposed based on their morphological characteristics. These new species are Bactrodesmium amazonicum sp. nov., Craspedodydymum brasiliense sp. nov., and Cancellidium estuarinum sp. nov. Additionally, new records of Cumulospora marina for the Americas and Virgariella caribensis, the second recorded instance in the world, have been reported. The results include descriptions, taxonomic comments, geographic distribution, and illustrations, all contributing to the knowledge of estuarine fungal diversity.

Drivers of seasonal and decadal change on an estuarine beach in a fetch-limited temperate embayment

Beaches in estuaries and bays (BEBs) are critical landforms along many coastlines, providing vital protection to human infrastructure and ecosystem services. Like open-ocean beaches, their morphodynamics are driven by the interaction of waves and tides with the boundary conditions determined by sediment supply and geology. However, as estuaries and bays tend to be lower energy than the open ocean, and are often fetch limited, BEB behaviour is typically controlled by high magnitude events rather than modal conditions. In this study, we assess the dynamics of a BEB in a semi-enclosed bay (Port Phillip Bay, Victoria, Australia). We analyse shoreline and subaerial cross sectional beach change across a range of time scales, including in response to storm events, using a combination of aerial photography, satellite imagery and UAV-based surveys spanning multiple decades. The study assesses the impact of geological controls on beach dynamics in this estuarine/embayed setting, investigating the impact of an intertidal rocky reef and the role of sediment budgets. The rocky outcrops throughout the compartment appear to exert little long-term control on beach morphology. We find that the location of the beach with respect to the sediment compartment boundaries is fundamental to determining long-term shoreline evolution. St Leonards Beach is located near the boundary between two longshore transport systems flowing in opposite directions. This results in low sediment flux across the compartment and therefore a paucity of sand supply for beach and dune development. As a consequence, the beach is relatively stable on a seasonal scale, but has a net erosional trend over the 75-year aerial photographic record. Erosion appears to be event driven as sand is transported out of the sediment compartment during storms. This work shows the importance of understanding local boundary conditions especially local sediment budgets in estuarine environments when analysing beach dynamics.

Reinforced human intervention drives microplastic pollution in estuarine beaches and nearshore sediments of Dongshan Bay, China

Sediments are generally recognized as a critical source and sink of microplastics (MPs), yet sedimentary MPs in the coastal areas are relatively overlooked. This study investigated MP pollution in estuarine beaches and nearshore sediments in Dongshan Bay in Southeastern China. The 23 sampling sites encompass the mangrove zone, west coast, south coast, east coast, and shipping-lane zone. MPs were evaluated by abundance, size, shape, color, composition, and morphology using microscopic identification, micro-Raman spectroscopy, and scanning electron microscopy. The abundance of MPs in surface sediments across Dongshan Bay manifested spatial heterogeneity, ranging from 31 to 971 items per kg d.w. The prominent concentration of MPs in the mid-west coast seemed to be driven by reinforced human intervention, namely, a giant facility under construction in the vicinity of the west coast. The major shape, color, and type of MPs were fiber, white and black, PES, PET, and PS, respectively. Friction, abrasions, scratches, and depressions were often present at the surfaces of MPs. The distribution patterns and hotspots of sedimentary MPs mirrored profound human footprints. This study provided insights into the assessment of estuarine ecosystem vulnerability and mitigation strategies against pressing sedimentary MP issues.

New species of Jahnula (Jahnulales, Dothideomycetes) and new records of aquatic ascomycetes from estuarine beaches of the Brazilian Amazon

ABSTRACT Estuaries are considered promising habitats for the presence of marine and freshwater fungal species because of their favourable environmental conditions. Janhula paraensis sp. nov. was found on decaying wood collected in the intertidal zone in fluvial beaches of Mosqueiro Island, Pará, Brazil. The new species differs from others in the genus by its morphology including dark brown ascospores, with thick and dark bands at septum when mature, a hyaline cap at both ends and the absence of a mucilaginous sheath. It was not possible to obtain molecular data for the new species. New records of Boerlagiomyces websteri, Corollospora pseudopulchella, Falciformispora lignatilis, and Savoryella lignicola for South America and Annulusmagnus triseptatus for Brazil are reported. Morphological descriptions and illustrations are presented for all species.

Spatial and temporal variability of microplastic abundance in estuarine intertidal sediments: Implications for sampling frequency

Microplastics (<5 mm) are well documented across shorelines worldwide; however, high variability in microplastic abundance is often observed within and among field studies. The majority of microplastic surveys to date consist of single sampling events that do not consider spatiotemporal variability as a potential confounding factor in the interpretation of their results. Therefore, these surveys may not accurately capture or reflect levels of microplastic contamination in the environment. Here, we provide the first investigation of small-scale spatial and temporal variability of microplastic abundance, distribution, and composition in the intertidal zone of an urbanized US estuary to better understand the short-term, daily spatiotemporal variability of microplastics in dynamic coastal environments. Intertidal sediment was collected from both the low and high intertidal zones of a sandy estuarine beach located in South Carolina, southeastern US every 1 to 2 days at low tide over 17 days (12 sampling events; total n = 72). Study-wide, microplastic abundance ranged from 44 to 912 microplastics/m2 and consisted primarily of polyethylene, nylon, polyester, and tire (or tyre) wear particles. High temporal variability was observed, with microplastic abundance differing significantly among sampling events (p = 0.00025), as well as among some consecutive tidal cycles occurring within 12 h of each other (p = 0.007). By contrast, low spatial variability was observed throughout the study with no significant differences in microplastic abundance detected between the low and high intertidal zones (p = 0.76). Of the environmental factors investigated, wind direction on the day of sampling had the greatest effect on temporal microplastic variability. Our results demonstrate that there can be significant temporal variability of microplastic abundance in estuarine intertidal sediments and are important for informing the methods and interpretation of future microplastic surveys in dynamic coastal environments worldwide.

Seasonal Morphological Variability on Estuarine Beaches and Implications for Low-Energy Beach Management

Mercaldi, B.; Brideau, L.E.; Tait, J.F., and Griggs, G., 2022. Seasonal morphological variability on estuarine beaches and implications for low-energy beach management. Journal of Coastal Research, 38(6), 1135–1147. Coconut Creek (Florida), ISSN 0749-0208. Estuarine beaches and other low-energy shorelines are critical for habitats and coastal infrastructure protection. Many different species inhabit estuaries because of the water bodies' unique characteristics, such as their mixed seawater and freshwater and variable tidal ranges. Estuarine beaches also have the important role of buffering storm wave energy. Yet, their natural physical processes are understudied. This research focuses on seasonal morphological variability of estuarine, low-energy beaches and evaluates the implications for beach management practices. Five sandy beaches were studied along the northern shoreline of Long Island Sound in the northeastern region of the United States. The studied beaches vary in location, width, length, and orientation within Long Island Sound to represent different exposures to wave energy. Three seasonal profiles were measured at each beach approximately every four months from late 2015 to early 2019 to document topographic changes. The results revealed minimal sediment movement throughout the study period and there was no evidence of significant cyclic cross-shore sediment transport to indicate patterns of seasonal profile changes. These findings reveal important implications for beach management practices on low-energy shorelines. Specifically, estuarine and other low-energy beaches should be studied on decadal time scales to document any long-term variability and post-storm recovery rather than the monthly or yearly time scales on which open-ocean beaches are typically evaluated. Additionally, estuarine beaches and other low-energy shorelines require specialized management practices that cater to their stagnancy to ensure adequate protection of coastal structures and infrastructure in the face of intensifying hurricanes and sea level rise.

Evolution and Sedimentation Mechanisms of Estuarine Beach in the Nakdong River Estuary, Korea: Natural and Human Impact

Evolution and Sedimentation Mechanisms of Estuarine Beach in the Nakdong River Estuary, Korea: Natural and Human Impact

Quantifying Estuarine Hydrometeorological Coastal Hazards Using a Combined Field Observation and Modeling Approach

Coastal development and its associated site management have rapidly expanded to estuarine environments while continuing to increase worldwide. With the growth of coastal management projects, field observations are required to understand how anthropogenic construction, coastal defense, environmental restoration, and conservation areas will react to the typical, extreme, and long-term conditions at the proposed sites. To address these unknowns, we present a multi-faceted coastal risk assessment of a unique, recently nourished estuarine beach near the mouth of the Delaware Bay Estuary by merging rapid-response remote sensing platforms, hydrodynamic models, and publically available monitoring datasets. Specifically, hydrometeorological events from 2015 to 2019 were the focus of peak-over-threshold statistics, event type definition, and clustered event interval determination. The 95th percentile thresholds were determined to be the following: 0.84 m for the significant wave height, 13.5 m/s for the 10-m elevation wind speed, and 0.4 m for the total water level residuals. Tropical and extra-tropical cyclones, light gales, or cold and stationary fronts proved to be the meteorological causes of the sediment mobility, inducing the hydrodynamics at the site. Using these event types and exceedance instances, clustered meteorological events were defined as having an interval greater than twelve hours but less than five days to be considered clustered. Clustered events were observed to cause greater volumetric change than individual events, and are currently underrepresented in coastal risk planning and response in the region. Coastal monitoring field measurements should consider clustered events when conducting post-hazardous or erosional event response surveys. This work highlights the importance of clustered hydrometeorological events causing estuarine coastal risk, and how to quantify these effects through combined field observations and modeling approaches.

Relationship between beach morphodynamics and body traits in a sand-dwelling wolf spider

Sandy beach macrofaunal communities are mainly structured by the independent response of species to the harsh physical environment. The theoretical framework for sandy beach ecology has been mainly developed on the basis of the outstanding role of morphodynamic factors on resident fauna in this narrow land-sea interface. In the case of supralittoral species, the habitat safety hypothesis (HSH) predicts an increase in body size and weight (among several individual and population attributes) from dissipative beaches (fine sand, gentle slope) to reflective beaches (coarse sand, steep slope). Spiders are relevant components of coastal ecosystems due to their strict dependence on prey availability and their carnivore condition; however, the HSH has never before been tested in this taxonomic group. We studied the relationship between beach morphodynamics and body size, weight and body condition of the wolf spider Allocosa marindia. We performed simultaneous collections of adults of A. marindia in two contiguous estuarine beaches with contrasting morphodynamics. As males were scarce, we measured and weighed only females. In agreement with predictions of the HSH, individuals were larger and heavier at the reflective beach. Individual size, weight and body condition were higher at the beginning of the reproductive period. Reflective beaches would act as more benign environments, providing secure microhabitats for the individuals and their potential prey, while affecting positively body traits during development. Our results provide the first formal testing of the HSH in a sand-dwelling spider on beaches with contrasting morphodynamics.

Sediment dispersal pattern along an engineered micro-tidal tropical estuarine beach

Sediment dispersal pattern along an engineered micro-tidal tropical estuarine beach

Evaluation of balneability index data of the main beaches of the metropolitan region of Belém, Pará, Brazil in the july 2016/2021 period

Water is a natural resource with great importance and diverse purposes of use; however, it is a limited resource. The beaches are dynamic environments, composed of sandy soils and sediment deposits caused by wave action, for this reason due to this mobility provides protection to the coast by the infl uence of waves. The beaches located in the Metropolitan Region of Belém - RMB, are considered estuarine beaches, due to the affl uence of the Guajará Bay and rivers of the Amazon. To evaluate the data of the bathing indices of the main beaches of the Metropolitan Region of Belém, PARÁ, BRAZIL in the period July 2016/2021. This is a quantitative study of descriptive analysis of data obtained from the agencies responsible for the analysis and dissemination of monitoring of the balneability of the beaches of the Metropolitan Region of Belém - RMB. An Excel table (Microsoft Excel 2016) was composed. In 2016, three beaches showed inconsistency in the results, being classifi ed as unsuitable for bathing, and these were the beaches of Baía do Sol, Amor and Cruzeiro, located respectively in the Districts of Mosqueiro, Outeiro and Icoaraci. This was the only year in which the two beaches located in the districts of Mosqueiro and Outeiro were classifi ed as unsuitable, in the period from 2016 to 2021, unlike Praia do Cruzeiro, in the District of Icoaraci, which presented problems in the years 2016, 2018, 2019 and 2020. Suggesting possible exacerbated anthropic activity at the site, improper sewage dumping or infl ow from other rivers. Urbanization, large tourist infl ux in certain months of the year, improperly dumped sewage, and rainfall may be preponderant factors in the accumulation of organic matter and reservoirs of parasites, viruses, and various enteric diseases. It can be concluded that the main beaches of the Metropolitan Region of Belém - RMB analyzed in this study, based on the data obtained by SEMMA, showed compliance with the legislation about monitoring, analysis, collection, environmental education, and dissemination of data to the population. Except for Cruzeiro Beach, in the District of Icoaraci, which showed non-compliance in the months of July in four years between 2016 and 2021.

Unravelling the role of local and large-scale factors in structuring sandy beach populations: the wedge clam Donax hanleyanus

Changes in the structure and dynamics of sandy beach macrofaunal populations result from the simultaneous action of local and regional factors acting synergistically. This is particularly noticeable in transitional interfaces between freshwater and marine ecosystems, where large-scale gradients affect local beach morphodynamics and resident fauna. The wedge clam Donax hanleyanus occurs on beaches with contrasting morphodynamics along the salinity gradient generated by the Rio de la Plata estuary. We conducted sampling surveys to determine a fine-grained comprehensive coverage of the species’ distribution in Uruguay to assess the concurrent effects of large-scale variations in salinity and local beach morphodynamics on wedge clam populations along 400 km (16 sandy beaches) over 2 yr. The main factor controlling wedge clam occurrence was salinity, overriding the effects of local habitat features. On beaches where the species was present, total abundance was higher on oceanic dissipative shores, which also harbored a higher abundance and relative representation of recruits. Recruitment was almost lacking in reflective beaches. However, biomass of adults with larger body sizes prevailed on reflective beaches, suggesting a scaling of abundance to body size and potential density-dependent effects. In this metapopulation, estuarine beaches are sinks, whereas oceanic beaches act as source habitats. We concluded that large-scale gradients generated by salinity variations translated into local population patterns (distribution, abundance and population structure) and processes (recruitment), which were secondarily driven by local morphodynamics. The relative importance of pre- and post-settlement processes across the morphodynamic spectrum from reflective to dissipative beaches has yet to be elucidated.

Evaluation of phenolic content of wrack debris on estuarine beaches: The effect on upper beach macrofauna

AbstractWrack supply represents the main organic input in sandy beaches ecosystems and is a common feature of beaches around the world. The chemical composition of the wrack is important in determining the extent and rate of the decay; in particular, phenolic compounds may affect consumption rates by wrack‐associated macrofauna and, consequently, modify the nutrient processing and recycling in sandy beaches. The aim of this research was to investigate the possible links between phenolic content of wrack supplies and the macrofaunal community inhabiting them. To achieve this, patches of wrack in three beaches of the NW coast of Spain were analysed and the phenolic contents and macrofaunal distribution, both at spatial and temporal scales, were assessed. Wrack and macrofaunal samples were collected along two shore‐parallel transects, coinciding with the wrack lines of previous tidal deposition. The results showed a general spatial distribution in the phenolic content of the beach‐cast according to their tidal position on the beach. Thus, two distinct zones were identified: the “spring‐tide deposited” zone located in the upper beach close to the base of the dunes and composed by wrack material with the lowest phenolic concentrations; and a “freshly deposited” zone with wrack deposits containing the highest concentrations of deterrent compounds. Nevertheless, only supratidal grazers, mostly linked to fresh deposits, have shown a slightly negative association between their abundance and the increasing phenolic contents of the stranded macroalgae. The lack of a consistent pattern in macrofaunal occupation of fresh and decayed drift lines detected suggests the species could be selecting habitats for reasons other than phenolic content.

Selectivity of marine-debris ingestion by juvenile green turtles (Chelonia mydas) at a South American World Heritage Listed area

Beaches in southern Brazil have substantial marine debris and strandings of dead juvenile green turtles (Chelonia mydas). This study investigates associations by quantifying marine debris (1) ingested among new (<40 cm curved carapace length; CCL) and older (≥40 cm CCL) juvenile C. mydas recruits; (2) concentrations on beach transects; and then (3) selective ingestion by C. mydas. Among 40 C. mydas (2014–2015), 93% had ingested debris, with smaller individuals having proportionally more. Sheet-like and hard plastics were the most frequently ingested, and commonly concentrated on beach transects. Estuarine beach transects had more debris than those facing the ocean. Selectivity analyses revealed all C. mydas avoided white miscellaneous debris and straws, while smaller conspecifics selected clear sheet-like plastics and avoided coloured ones. The results reiterate a need for long-term reforms to regional waste disposal and short-term initiatives encouraging social awareness to avoid key plastics and reduce ingestion by C. mydas.

Age and reproduction of the southern king croaker Menticirrhus americanus in subtropical South Atlantic environments

Menticirrhus americanus were sampled (n = 393) from two beaches (P1 is an estuarine beach near the mouth of the Paranaguá Estuarine Complex, and P2 is a beach adjacent to the Paranaguá Estuarine Complex) in the subtropical region of the western South Atlantic waters between August 2015 and June 2016. This study aimed to identify the spawning season and the age structure for M. americanus using two sampling methods. For sampling at the P1 beach, seine, line, and pole were used, while samples from the P2 beach were obtained from the artisanal fishers. Females were numerically dominant in all sampling months at both sites except for February when the males became dominant. The species exhibited a protected reproductive season with multiple spawning peaks between August and December. Males and females were captured at all gonadal development stages and ages between 1 and 6 from both sites. At first maturity, the length of the females was 16.3 cm, and the mean age at first maturity was 1.3 years. Individuals aged between 1 and 3 years were dominant (68%). The results suggested that young and adults of the M. americanus use the same habitats throughout their ontogeny.

The Effects of Wind-Driven Storm Events on Partly Sheltered Estuarine Beaches in Batemans Bay, New South Wales, Australia

Extreme wind-driven storm events have the potential to erode beach systems. Along the East Coast of Australia, storm events have been responsible for beach erosion in many coast-facing, open beaches. This paper investigates the potential impacts of wind-driven storms on partly sheltered estuarine beaches—a niche found within Batemans Bay, New South Wales (NSW), along the East Coast. It combines beach geomorphological data with meteorological and oceanographic data to evaluate the impacts of large storm events on three partly sheltered estuarine embayed beaches (Cullendulla Beach, Corrigans Beach, and Maloney’s Beach). The results show that while embayed beaches are protected from some storm events, storm impacts may vary with the season due to wind speed and direction changes, the presence of nearby rivers or creeks, and anthropogenic modifications such as dredging and coastline alterations. This study may contribute to the understanding of the erosive impacts of storms and help improve management strategies used to prevent recession, particularly on embayed beaches.