Intertidal Beach Sand Research Articles

Bather Shedding as a Source of Human Fecal Markers to a Recreational Beach.

Microbial source tracking (MST) can identify and locate surf zone fecal indicator bacteria (FIB) sources. However, DNA-based fecal marker results may raise new questions, since FIB and DNA marker sources can differ. Here, during 2 years of summertime (dry season) MST for a Goleta, California recreational beach, surf zone FIB were mainly from gulls, yet low level human-associated DNA-based fecal marker (HF183) was detected in 25 and 14% of surf zone water samples, respectively. Watershed sources were hypothesized because dry weather creek waters had elevated FIB, and runoff-generating rain events mobilized human (and dog) fecal markers and Salmonella spp. into creeks, with human marker HF183 detected in 40 and 50% of creek water samples, dog markers detected in 70 and 50% of samples, and Salmonella spp. in 40 and 33.3% of samples, respectively over 2 years. However, the dry weather estuary outlet was bermed in the first study year; simultaneously, creek fecal markers and pathogens were lower or similar to surf zone results. Although the berm breached in the second year, surf zone fecal markers stayed low. Watershed sediments, intertidal beach sands, and nearshore sediments were devoid of HF183 and dog-associated DNA markers. Based on dye tests and groundwater sampling, beach sanitary sewers were not leaking; groundwater was also devoid of HF183. Offshore sources appeared unlikely, since FIB and fecal markers decreased along a spatial gradient from the surf zone toward nearshore and offshore ocean waters. Further, like other regional beaches, surf zone HF183 corresponded significantly to bather counts, especially in the afternoons when there were more swimmers. However, morning detections of surf zone HF183 when there were few swimmers raised the possibility that the wastewater treatment plant (WWTP) offshore outfall discharged HF183 overnight which transported to the surf zone. These findings support that there may be lowest achievable limits of surf zone HF183 owing to several chronic and permanent, perhaps diurnal, low concentration sources.

Assessment of radioactivity concentration in intertidal sediments from coastal provinces in Oman and estimation of hazard and radiation indices

The natural radioactivity of intertidal sediment samples collected from the beaches of Oman was investigated. Using gamma ray spectrometry, the activity concentrations of 226Ra, 232Th and 40K in the sediment samples were measured to have average values of 20.49 ± 3.50, 2.26 ± 0.60 and 44.83 ± 4.60 Bq kg−1 respectively. The activity levels reported are considerably lower than the worldwide average. The annual effective dose rate was estimated to be 0.015 mSv yr−1 on average. Additionally, the mean radium equivalent, external and internal indices were 26.89, 0.07 and 0.13 Bq kg−1 respectively which were well below the risk limits. Gamma and alpha radiation indices were computed to be less than unity and show no exceedance beyond the recommended level. Our results provide baseline data for radioactivity in intertidal sediment samples of Oman and show that intertidal beach sand does not pose significant radiological risk to human health.

Microbial community structure shows differing levels of temporal stability in intertidal beach sands of the grand strand region of South Carolina.

Studies of microbial community structure in intertidal and supratidal beach sands along the California and Gulf of Mexico coasts have begun to reveal geographical patterns in microbial diversity through the use of next generation sequencing technology. Only a few studies have targeted communities along the Eastern seaboard, leaving a variety of microbial ecosystems uncharacterized. In this study, we examine the microbial community structure within three South Carolina beaches along the Grand Strand via sequencing of the V4 region of the 16S rRNA gene to discern relationships between diversity and temporal or regional factors. Gammaproteobacteria, Planctomycetes, Acidobacteria, and Actinobacteria dominated the composition of these beaches. Diversity analyses revealed that highly diverse communities were similar in overall composition and diversity but showed different levels of community structure stability over time. The community structure in Pawleys Island sands showed no significant change over time, while Garden City experienced significant shifts between each sampling date. Community structure also differed between beaches and, to a lesser degree, sampling date. These data provide evidence of the high microbial diversity within these beach sands and suggest that even though beaches of the same geographic region can show similarity in composition and diversity at a particular timepoint, the nature of their community structure and underlying diversity may differ comparatively and over time.

Prevalence and Characterization of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus on Public Recreational Beaches in Northeast Ohio.

Staphylococcus aureus can cause severe life‐threatening illnesses such as sepsis and endocarditis. Although S. aureus has been isolated from marine water and intertidal beach sand, only a few studies have been conducted to assess prevalence of S. aureus at freshwater recreational beaches. As such, we aimed to determine prevalence and molecular characteristics of S. aureus in water and sand at 10 freshwater recreational beaches in Northeast Ohio, USA. Samples were analyzed using standard microbiology methods, and resulting isolates were typed by spa typing and multilocus sequence typing. The overall prevalence of S. aureus in sand and water samples was 22.8% (64/280). The prevalence of methicillin‐resistant S. aureus (MRSA) was 8.2% (23/280). The highest prevalence was observed in summer (45.8%; 55/120) compared to fall (4.2%; 5/120) and spring (10.0%; 4/40). The overall prevalence of Panton‐Valentine leukocidin genes among S. aureus isolates was 21.4% (15/70), and 27 different spa types were identified. The results of this study indicate that beach sand and freshwater of Northeast Ohio were contaminated with S. aureus, including MRSA. The high prevalence of S. aureus in summer months and presence of human‐associated strains may indicate the possibility of role of human activity in S. aureus contamination of beach water and sand. While there are several possible routes for S. aureus contamination, S. aureus prevalence was higher in sites with wastewater treatment plants proximal to the beaches.

Deep oxygen penetration drives nitrification in intertidal beach sands

AbstractWe discovered a hotspot of elevated nitrate concentration (median = 431 μM) in shallow beach pore water that extended across the entire length of two barrier islands in the southeastern United States of America. We investigated this feature by surveying groundwater geochemistry, measuring fluctuations in in situ dissolved oxygen (DO) concentrations, modeling groundwater flow, and quantifying nitrification rates. Nitrification of groundwater ammonium was the only possible nitrate source, with a measured potential rate of 0.84 μmol m−2 h−1. However, the observed nitrate concentrations were far in excess of the predicted maximum achievable by aerobic nitrification assuming a 2 : 1 ratio of O : N and around 200 μM DO in air‐saturated seawater. Groundwater DO concentrations within the hotspot (65 cm depth) were consistently 20–50 μM. The nitrate hotspot was located at the top of the water table beneath dry, undersaturated sand that allowed the penetration of air and the dissolution of excess oxygen into the pore fluids. The total dissolved nitrogen concentration of the hotspot was higher than anywhere else on the island, indicating nitrogen accumulation within the hotspot, most likely via ammonium adsorption. Vertical dispersion was the dominant pathway for nitrate loss from the hotspot. This nitrate was consumed in underlying anoxic sand, coupling microbial pathways of nitrogen oxidation and reduction and removing bioavailable nitrogen from the beach ecosystem.

Antimicrobial Susceptibility of Staphylococcus aureus Isolated from Recreational Waters and Beach Sand in Eastern Cape Province of South Africa.

Background: Resistance of Staphylococcus aureus to commonly used antibiotics is linked to their ability to acquire and disseminate antimicrobial-resistant determinants in nature, and the marine environment may serve as a reservoir for antibiotic-resistant bacteria. This study determined the antibiotic sensitivity profile of S. aureus isolated from selected beach water and intertidal beach sand in the Eastern Cape Province of South Africa. Methods: Two hundred and forty-nine beach sand and water samples were obtained from 10 beaches from April 2015 to April 2016. Staphylococcus aureus was isolated from the samples using standard microbiological methods and subjected to susceptibility testing to 15 antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) was detected by susceptibility to oxacillin and growth on Brilliance MRSA II agar. Antibiotic resistance genes including mecA, femA rpoB, blaZ, ermB, ermA, ermC, vanA, vanB, tetK and tetM were screened. Results: Thirty isolates (12.3%) were positive for S. aureus by PCR with over 50% showing phenotypic resistance to methicillin. Resistance of S. aureus to antibiotics varied considerably with the highest resistance recorded to ampicillin and penicillin (96.7%), rifampicin and clindamycin (80%), oxacillin (73.3%) and erythromycin (70%). S. aureus revealed varying susceptibility to imipenem (96.7%), levofloxacin (86.7%), chloramphenicol (83.3%), cefoxitin (76.7%), ciprofloxacin (66.7%), gentamycin (63.3%), tetracycline and sulfamethoxazole-trimethoprim (56.7%), and vancomycin and doxycycline (50%). All 30 (100%) S. aureus isolates showed multiple antibiotic-resistant patterns (resistant to three or more antibiotics). The mecA, femA, rpoB, blaZ, ermB and tetM genes were detected in 5 (22.7%), 16 (53.3%), 11 (45.8%), 16 (55.2%), 15 (71.4%), and 8 (72.7%) isolates respectively; Conclusions: Results from this study indicate that beach water and sand from the Eastern Cape Province of South Africa may be potential reservoirs of antibiotic-resistant S. aureus which could be transmitted to exposed humans and animals.

Pollutant advective spreading in beach sand exposed to high-energy tides

This paper presents field measurements in which dye solute was injected into coastal sand to investigate contaminant advection in intertidal beach sand. The measurements show the pathways of a contaminated plume in the unsaturated zone during both the flood and ebb tides. A prescribed amount of dye tracer solution was directly injected through the topsoil, with average porosity 0.3521 ± 0.01, at predetermined locations of the River Mersey's outer estuarial beach during ebb-tide. The injected dye was monitored, sampled and photographed over several tidal cycles. The distinctive features of the plume (full two dimensional cross-sections), sediments and water-table depth were sampled in-situ, close to the injection point (differing from previous contaminant monitoring tests in aquifers). The advective movement is attributed to tidal impact which is different from contaminant transport in aquifers. The experimental results show that plumes have significantly large spatial variability, diverging upwards and converging downwards, with a conical geometric shape which is different from the usual spherical/elliptical shape reported in literature. The mean vertical motion of the plume reaches three times the top-width within ten tidal cycles, exceeding the narrow bottom-width by a factor of order 2. The observed transport features of the plume within the beach sand have significant relevance to saltwater intrusion, surface water and groundwater quality. The field observations are unique and can serve as a valuable benchmark database for relevant numerical studies.

Understanding and predicting the temporal variability of sediment grain size characteristics on high-energy beaches

Despite representing a key parameter when modelling morphology or sediment transport, surface sediments are often assumed homogenous, with grain size temporally constant. This contribution uses a 6-year data set of monthly sediment samples to quantify the observed variability in intertidal beach sands at four energetic, macrotidal locations (North Cornwall, UK). Changes in grain size and sorting were related to periods of high-steepness storm waves promoting a relatively rapid coarsening and an improvement in sorting and low-steepness swell waves, a fining and a reduction in sorting. These temporal changes in intertidal grain size were coherently linked to the disequilibrium in wave steepness, with peak coarsening occurring when the instantaneous wave steepness conditions vastly exceeded a temporally evolving antecedent time series. Using this concept, a simple model is proposed that provides skilful predictions of the unseen variability in sediment grain size (average r2=0.86, p<0.01) and sorting (average r2=0.75, p<0.05), at all four sites.

Characterization of methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus spp. isolated from US West Coast public marine beaches

The aim of this study was to isolate and characterize methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus spp. (MRCoNS) from marine water and intertidal beach sand from public beaches in Washington State, USA. Fifty-one staphylococci from Washington State beaches were characterized using antimicrobial susceptibility testing, carriage of acquired tetracycline and/or macrolide resistance genes, staphylococcal cassette chromosome mec (SCCmec) typing, the BBL Crystal Gram-Positive ID System and/or 16S rRNA sequencing, coagulase test and multilocus sequence typing (MLST) for MRSA. Five multidrug-resistant MRSA SCCmec type I, of which three were MLST type ST45, one ST59 and one a new MLST type, ST1405, plus one susceptible non-typeable (NT) MRSA ST30 were characterized. Thirty-three MRCoNS isolates, representing 21 strains from 9 Staphylococcus spp., carried a range of SCCmec types [I (2), II (6), III (3), V (2), I/II (1) and NT (7)] and varied in their antibiotic susceptibility to other antibiotic classes and carriage of acquired tetracycline/macrolide resistance gene(s). MRSA and MRCoNS donors co-transferred tet(M) and erm(A) genes to an Enterococcus faecalis recipient at a frequency of 10(-8). This is the first report of MRSA and MRCoNS isolated from marine water and intertidal beach sand. The MLST types and antibiotic carriage of five MRSA isolates were similar to hospital MRSA isolates rather than US community-acquired MRSA isolates. Our results suggest that public marine beaches may be a reservoir for transmission of MRSA to beach visitors as well as an ecosystem for exchange of antibiotic resistance genes among staphylococci and related genera.

Photochemical production of hydrogen peroxide in size-fractionated Southern California coastal waters

Hydrogen peroxide (H 2O 2) photochemical production was measured in bulk and size-fractionated surf zone and source waters (Orange County, California, USA). Post-irradiation (60 min; 300 W ozone-free xenon lamp), maximum H 2O 2 concentrations were ∼10 000 nM (source) and ∼1500 nM (surf zone). Average initial hydrogen peroxide production rates (HPPR) were higher in bulk source waters (11 ± 7.0 nM s −1) than the surf zone (2.5 ± 1 nM s −1). A linear relationship was observed between non-purgeable dissolved organic carbon and absorbance coefficient (m −1 (300 nm)). HPPR increased with increasing absorbance coefficient for bulk and size-fractionated source waters, consistent with photochemical production from CDOM. However, HPPR varied significantly (5×) for surf zone samples with the same absorbance coefficients, even though optical properties suggested CDOM from salt marsh source waters dominates the surf zone. To compare samples with varying CDOM levels, apparent quantum yields ( Φ) for H 2O 2 photochemical production were calculated. Source waters showed no significant difference in Φ between bulk, large (>1000 Da (>1 kDa)) and small (<1 kDa) size fractions, suggesting H 2O 2 production efficiency is homogeneously distributed across CDOM size. However, surf zone waters had significantly higher Φ than source (bulk 0.086 ± 0.04 vs. 0.034 ± 0.013; <1 kDa 0.183 ± 0.012 vs. 0.027 ± 0.018; >1 kDa 0.151 ± 0.090 vs. 0.016 ± 0.009), suggesting additional production from non-CDOM sources. H 2O 2 photochemical production was significant for intertidal beach sand and senescent kelp (sunlight; ∼42 nM h −1 vs. ∼5 nM h −1), on the order of CDOM production rates previously measured in coastal and oceanic waters. This is the first study of H 2O 2 photochemical production in size-fractionated coastal waters showing significant production from non-CDOM sources in the surf zone.

Live transport and marketing of spiny lobsters in India

Eight species of spiny lobster (six littoral and two deep-sea) and two species of slipper lobster constitute the lobster fishery of India. Lobster landings fluctuate around 2000–3000 t annually. High export demand for Indian spiny lobsters has resulted in regular and organized exploitation, both inshore and offshore. Almost the entire quantity of lobsters landed in India is exported in frozen, cooked or live form. Export of live lobsters, which realize the maximum unit price, has increased from 22 t in 1994 to 97 t in 1996. Live transport of spiny lobsters has advanced from just keeping them alive for a few hours in moist intertidal beach sand to the most sophisticated packing in insulated boxes. The process involves holding the lobsters at the landing centre and at the city of export. The entire exercise lasts about seven days, during which period the lobsters are packed twice, each time keeping them out of water for not less than 20 h. In the holding centres, the lobsters are often kept at high densities, with the resulting build-up of nitrogenous wastes and depletion of dissolved oxygen leading to mortalities. Average mortality is up to 6.5% during live transport.

Intertidal beach sands as monitors for heavy metal pollution in coastal water bodies

Abstract Intertidal beach sands were investigated for their use as indicators of metal transport in a contaminated water body, Sepetiba Bay, Rio de Janeiro, Brazil, and are proposed as an alternative and rapid screening method to determine metal pollution status of coastal areas. The results showed that, at least for Cu, Cr, Zn and Pb, beach sands can be included in the existing environmental monitoring programs for heavy metal pollution in water bodies.

Microbial RNA and DNA synthesis in marine sediments

A technique for measuring rates of RNA and DNA synthesis in sedimentary microbial communities has been adapted from methods developed for marine and freshwater microplankton research. The procedure measures the uptake, incorporation and turnover of exogenous [2, 3H]-adenine by benthic microbial populations. With minor modification, it is applicable to a wide range of sediment types. Measurement of nucleic acid synthesis rates are reported from selected benthic marine environments, including coral reef sediments (Kaneohe Bay, Oahu, Hawaii), intertidal beach sands (Oahu and southern California) and California borderland basin sediment (San Pedro Basin), and comparisons are made to selected water-column microbial communities. Biomass-specific rates of nucleic acid synthesis in sediment microbial communities were comparable to those observed in water-column assemblages (i.e., 0.02 to 2.0 pmol deoxyadenine incorporated into DNA [ng ATP]-1 h-1 and 0.2 to 8.9 pmol adenine incorporated into RNA [ng ATP]-1 h-1). DNA synthesis rates were used to calculate carbon production estimates ranging from 2 μg C cm-3 h-1 in San Pedro Basin sediment (880 m water depth) to 807 μg C cm-3 h-1 in coral reef sediment from the Kaneohe Bay. Microbial community specific growth rate, μ(d-1), estimated from DNA synthesis rates in surface sediments ranged from 0.1 in San Pedro Basin to 4.2 in Scripps Beach (La Jolla, California) intertidal sand.

Upper Jurassic coal-bearing shoreline deposits, Hochstetter Forland, east Greenland

Upper Jurassic coal-bearing yellow sandstones occur at several localities on Hochstetter Forland, northern east Greenland. The sandstones have been divided into eight sedimentary facies, each facies characterized by an assemblage of sedimentary structures, a specific lithology and, occasionally by the content of fossils, notably oysters. The interpretations of the established facies range from high subtidal oyster banks over intertidal beach sand to lagoonal and coastal swamp deposits. The sedimentary facies occur in a vertical sequence where two slightly different facies associations could be discerned. It is suggested that both facies associations have been deposited in a barrier—lagoon coastal area characterized by minor shoreline oscillations. The palaeogeographic setting of the investigated sequence in the fault-controlled basins along the east Greenland continental margin is discussed.

Action of urea on calf-thymus deoxyribonucleic acid

Despite representing a key parameter when modelling morphology or sediment transport, surface sediments are often assumed homogenous, with grain size temporally constant. This contribution uses a 6-year data set of monthly sediment samples to quantify the observed variability in intertidal beach sands at four energetic, macrotidal locations (North Cornwall, UK). Changes in grain size and sorting were related to periods of high-steepness storm waves promoting a relatively rapid coarsening and an improvement in sorting and low-steepness swell waves, a fining and a reduction in sorting. These temporal changes in intertidal grain size were coherently linked to the disequilibrium in wave steepness, with peak coarsening occurring when the instantaneous wave steepness conditions vastly exceeded a temporally evolving antecedent time series. Using this concept, a simple model is proposed that provides skilful predictions of the unseen variability in sediment grain size (average r2 = 0.86, p < 0.01) and sorting (average r2 = 0.75, p < 0.05), at all four sites.