Viruses In Seawater Research Articles

Microcosm experiment investigating climate-induced thermal effects on human virus viability in seawater: qPCR vs capsid integrity for enhanced risk management

Climate change is intensifying extreme weather events in coastal areas, leading to more frequent discharge of untreated wastewater containing human viruses into coastal waters. This poses a health risk, especially during heatwaves when bathing activity increases. A study examined the survival and viability of seven common wastewater viruses in seawater at different temperatures. Viral genomes were quantified using direct qPCR, whilst viability was assessed using Capsid Integrity qPCR. Results showed that T90 values from direct qPCR were much higher than those from CI-qPCR, suggesting that risk mitigation should be based on viral integrity tests. All viruses remained potentially viable for at least 72 h in environmental seawater and longer in sterile artificial seawater, highlighting the importance of biotic processes in viral inactivation. Viral persistence decreased with increasing temperature. Whilst heatwaves may partially reduce risks from human viral pathogens in coastal waters, they do not eliminate them entirely.

Rapid and efficient inactivation of viruses in seawater by LIG electrodes

Water-borne viral diseases are a significant concern for public health. In particular, they threaten the health of people and animals in countries that lack proper water treatment facilities. Novel water treatment technology may efficiently improve water quality and prevent the spread of waterborne viral pathogens. Laser-induced graphene (LIG) has been shown to inactivate viruses and bacteria with its photothermal properties, electrochemical reaction, and rough surface texture. However, LIG's activity to prevent virus transmission via contaminated water has not been fully explored. Here, we demonstrated that enveloped and non-enveloped viruses in seawater could be rapidly inactivated by LIG technology. After being activated by 3 V of electricity, the LIG electrodes inactivated both types of viruses spiked in water within 30 min. In addition, the electrolyzed seawater exhibited virucidal effects even after the cessation of the electrical charge. The generation of different oxidants, such as chlorine, chlorine dioxide, and hydrogen peroxide, may play an essential role in the antiviral mechanism of the LIG electrodes. Furthermore, after 10 min of electrolysis, the pH of the seawater dropped from approximately 8–5, which may also have contributed to the virucidal effects of the LIG technology. The virucidal activity of LIG technology highlighted its potential for preventing the spread of viral infections via seawater systems which may have public health implications in areas where seawater is used in the sewage system. It may also have applications in aquaculture, where viral diseases do not have treatments and can cause high fish mortality.

Genomic and transcriptomic insights into complex virus–prokaryote interactions in marine biofilms

Marine biofilms are complex communities of microorganisms that play a crucial ecological role in oceans. Although prokaryotes are the dominant members of these biofilms, little is known about their interactions with viruses. By analysing publicly available and newly sequenced metagenomic data, we identified 2446 virus–prokaryote connections in 84 marine biofilms. Most of these connections were between the bacteriophages in the Uroviricota phylum and the bacteria of Proteobacteria, Cyanobacteria and Bacteroidota. The network of virus–host pairs is complex; a single virus can infect multiple prokaryotic populations or a single prokaryote is susceptible to several viral populations. Analysis of genomes of paired prokaryotes and viruses revealed the presence of 425 putative auxiliary metabolic genes (AMGs), 239 viral genes related to restriction–modification (RM) systems and 38,538 prokaryotic anti-viral defence-related genes involved in 15 defence systems. Transcriptomic evidence from newly established biofilms revealed the expression of viral genes, including AMGs and RM, and prokaryotic defence systems, indicating the active interplay between viruses and prokaryotes. A comparison between biofilms and seawater showed that biofilm prokaryotes have more abundant defence genes than seawater prokaryotes, and the defence gene composition differs between biofilms and the surrounding seawater. Overall, our study unveiled active viruses in natural biofilms and their complex interplay with prokaryotes, which may result in the blooming of defence strategists in biofilms. The detachment of bloomed defence strategists may reduce the infectivity of viruses in seawater and result in the emergence of a novel role of marine biofilms.

Marine viruses disperse bidirectionally along the natural water cycle

Marine viruses in seawater have frequently been studied, yet their dispersal from neuston ecosystems at the air-sea interface towards the atmosphere remains a knowledge gap. Here, we show that 6.2% of the studied virus population were shared between air-sea interface ecosystems and rainwater. Virus enrichment in the 1-mm thin surface microlayer and sea foams happened selectively, and variant analysis proved virus transfer to aerosols collected at ~2 m height above sea level and rain. Viruses detected in rain and these aerosols showed a significantly higher percent G/C base content compared to marine viruses. CRISPR spacer matches of marine prokaryotes to foreign viruses from rainwater prove regular virus-host encounters at the air-sea interface. Our findings on aerosolization, adaptations, and dispersal support transmission of viruses along the natural water cycle.

Porcine Epidemic Diarrhea Virus, Surrogate for Coronavirus Decay Measurement in French Coastal Waters and Contribution to Coronavirus Risk Evaluation.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in infected patients mainly displays pulmonary and oronasal tropism; however, the presence of the virus has also been demonstrated in the stools of patients and consequently in wastewater treatment plant effluents, raising the question of the potential risk of environmental contamination (such as seawater contamination) through inadequately treated wastewater spillover into surface or coastal waters even if the environmental detection of viral RNA alone does not substantiate risk of infection. Therefore, here, we decided to experimentally evaluate the persistence of the porcine epidemic diarrhea virus (PEDv), considered as a coronavirus representative model, in the coastal environment of France. Coastal seawater was collected, sterile-filtered, and inoculated with PEDv before incubation for 0 to 4 weeks at four temperatures representative of those measured along the French coasts throughout the year (4, 8, 15, and 24°C). The decay rate of PEDv was determined using mathematical modeling and was used to determine the half-life of the virus along the French coast in accordance with temperatures from 2000 to 2021. We experimentally observed an inverse correlation between seawater temperature and the persistence of infectious viruses in seawater and confirm that the risk of transmission of infectious viruses from contaminated stool in wastewater to seawater during recreational practices is very limited. The present work represents a good model to assess the persistence of coronaviruses in coastal environments and contributes to risk evaluation, not only for SARS-CoV-2 persistence, but also for other coronaviruses, specifically enteric coronaviruses from livestock. IMPORTANCE The present work addresses the question of the persistence of coronavirus in marine environments because SARS-CoV-2 is regularly detected in wastewater treatment plants, and the coastal environment, subjected to increasing anthropogenic pressure and the final receiver of surface waters and sometimes insufficiently depurated wastewater, is particularly at risk. The problem also arises in the possibility of soil contamination by CoV from animals, especially livestock, during manure application, where, by soil impregnation and runoff, these viruses can end up in seawater. Our findings are of interest to researchers and authorities seeking to monitor coronaviruses in the environment, either in tourist areas or in regions of the world where centralized systems for wastewater treatment are not implemented, and more broadly, to the scientific community involved in "One Health" approaches.

A remarkably diverse and well-organized virus community in a filter-feeding oyster

BackgroundViruses play critical roles in the marine environment because of their interactions with an extremely broad range of potential hosts. Many studies of viruses in seawater have been published, but viruses that inhabit marine animals have been largely neglected. Oysters are keystone species in coastal ecosystems, yet as filter-feeding bivalves with very large roosting numbers and species co-habitation, it is not clear what role they play in marine virus transmission and coastal microbiome regulation.ResultsHere, we report a Dataset of Oyster Virome (DOV) that contains 728,784 nonredundant viral operational taxonomic unit contigs (≥ 800 bp) and 3473 high-quality viral genomes, enabling the first comprehensive overview of both DNA and RNA viral communities in the oyster Crassostrea hongkongensis. We discovered tremendous diversity among novel viruses that inhabit this oyster using multiple approaches, including reads recruitment, viral operational taxonomic units, and high-quality virus genomes. Our results show that these viruses are very different from viruses in the oceans or other habitats. In particular, the high diversity of novel circoviruses that we found in the oysters indicates that oysters may be potential hotspots for circoviruses. Notably, the viruses that were enriched in oysters are not random but are well-organized communities that can respond to changes in the health state of the host and the external environment at both compositional and functional levels.ConclusionsIn this study, we generated a first “knowledge landscape” of the oyster virome, which has increased the number of known oyster-related viruses by tens of thousands. Our results suggest that oysters provide a unique habitat that is different from that of seawater, and highlight the importance of filter-feeding bivalves for marine virus exploration as well as their essential but still invisible roles in regulating marine ecosystems.APUP9ceFw5rgMggB2pWS5VVideo

Application of iron flocculation to concentrate white spot syndrome virus in seawater

The iron flocculation method, which comprises the Fe-virus flocculate formation-filtration-resuspension steps, is extensively used to concentrate and precipitate viruses distributed in water. To apply this method to concentrate white spot syndrome virus (WSSV) in seawater, viral genomic and infective recovery yields were compared between polyethylene sulfone (PES) and polycarbonate (PC) membrane filters and two types of resuspension buffers (oxalate and ascorbate). Viral genome quantitation was determined above a 95 % limit of detection (11.48 viral DNA copies/μL) using quantitative real-time PCR. From WSSV-spiked seawater (100–106 viral DNA copies/mL), the viral genomic recovery yields of the PES-Oxalate, PC-Oxalate, PES-Ascorbate, and PC-Ascorbate conditions were 78.67 % ± 12.90 %, 84.53 % ± 24.30 %, 85.59 % ± 16.98 %, and 93.74 % ± 7.44 %, respectively. The detectable Fe-virus flocculates collected by the PC membrane were approximately 101 WSSV DNA copies/mL of seawater, a value more than 10-fold higher than that compared to the PES membrane filter (102 WSSV DNA copies/mL), regardless of the resuspension buffer types. WSSV resuspended with oxalate buffer caused mass mortality among whiteleg shrimp (Litopenaeus vannamei), inducing the expression of the virus envelope protein, VP28, similar to that of a native virus, suggesting stable viral activity during the resuspension process. Based on the PES-Ascorbate, WSSV particles could be successfully concentrated in seawater from shrimp farms with white spot disease outbreaks (approximately 102 WSSV DNA copies/mL). Collectively, these findings indicate that the simple and efficient method of iron flocculation is sufficient to concentrate WSSV in seawater and could be used as a non-invasive approach and one of the reasonable diagnostic processes for white spot disease surveillance.

Short communication: Evaluation of charged membrane filters and buffers for concentration and recovery of infectious salmon anaemia virus in seawater.

Infectious salmon anaemia virus (ISAV) is the cause of an important waterborne disease of farmed Atlantic salmon. Detection of virus in water samples may constitute an alternative method to sacrificing fish for surveillance of fish populations for the presence of ISA-virus. We aimed to evaluate different membrane filters and buffers for concentration and recovery of ISAV in seawater, prior to molecular detection. One litre each of artificial and natural seawater was spiked with ISAV, followed by concentration with different filters and subsequent elution with different buffers. The negatively charged MF hydrophilic membrane filter, combined with NucliSENS® lysis buffer, presented the highest ISAV recovery percentages with 12.5 ± 1.3% by RT-qPCR and 31.7 ± 10.7% by RT-ddPCR. For the positively charged 1 MDS Zeta Plus® Virosorb® membrane filter, combined with NucliSENS® lysis buffer, the ISAV recovery percentages were 3.4 ± 0.1% by RT-qPCR and 10.8 ± 14.2% by RT-ddPCR. The limits of quantification (LOQ) were estimated to be 2.2 x 103 ISAV copies/L of natural seawater for both RT-qPCR and RT-ddPCR. The ISAV concentration method was more efficient in natural seawater.

Use of anionic polymer-coated magnetic beads to pre-concentrate Ostreid Herpesvirus 1 from seawater: Application to a UV disinfection treatment

Ostreid Herpesvirus 1 (OsHV-1) represents a serious threat to shellfish aquaculture worldwide. To minimise its impact, early warning systems able to detect the virus in seawater prior to infection of oysters are of utmost importance. However, monitoring OsHV-1 in seawater is challenging because of its presence at very low concentrations. Thus, a rapid and simple method to pre-concentrate the virus is needed to enable detection. Herein, magnetic beads (MBs) coated with an anionic polymer were used to pre-concentrate OsHV-1 from biological matrices including oyster homogenate and seawater samples. Following virus capture, OsHV-1 DNA detection was performed by quantitative PCR (qPCR). The MB-based approach combined with qPCR attained a limit of detection (LOD) as low as 0.1 viral copy/μL, which was 100 times lower than that of the qPCR alone. This approach was applied to the analysis of OsHV-1 in seawater from an Enhanced Hydro-Optic UV (HOD-UV) disinfection experiment operating at a UV dose of 1360 J/m2 in an open flow system. Our approach enabled detection of the virus in non-treated seawater and not in UV-treated seawater, discrimination that was not possible using qPCR alone. Moreover, the strategy provided data on the pattern of kinetics of the release of the virus in seawater. The approach could find applications in shellfish hatcheries and depuration plants to ensure biosecurity requirements.

Expanding our understanding of marine viral diversity through metagenomic analyses of biofilms.

Recent metagenomics surveys have provided insights into the marine virosphere. However, these surveys have focused solely on viruses in seawater, neglecting those associated with biofilms. By analyzing 1.75 terabases of biofilm metagenomic data, 3974 viral sequences were identified from eight locations around the world. Over 90% of these viral sequences were not found in previously reported datasets. Comparisons between biofilm and seawater metagenomes identified viruses that are endemic to the biofilm niche. Analysis of viral sequences integrated within biofilm-derived microbial genomes revealed potential functional genes for trimeric autotransporter adhesin and polysaccharide metabolism, which may contribute to biofilm formation by the bacterial hosts. However, more than 70% of the genes could not be annotated. These findings show marine biofilms to be a reservoir of novel viruses and have enhanced our understanding of natural virus-bacteria ecosystems.

Decay rate of virus and faecal indicator bacteria (FIB) in seawater and the concentration of FIBs in different wastewater systems

Information about the concentration, growth and decay rates of enteric microorganisms in different wastewater systems and water bodies is crucial for quantitative microbial risk assessment (QMRA). In general, there is little information about this and in particular about the decay rates of faecal bacteria and viruses at different depths of the marine environment where many wastewater treatment plants discharge their effluent. This study was designed to investigate the concentration of faecal indicator bacteria (FIB) in different types of wastewater, the potential for growth of FIB in greywater, and the decay rates of FIB and pathogenic viruses in seawater samples from different depths. The intent of this work was to mimic summer water quality. Average concentrations of total coliforms (TC), Escherichia coli (E. coli) and intestinal enterococci (IE) (log10 per 100 ml) were 7.2, 6.7 and 6.1 in blackwater; 6.7, 6.1 and 3.8 in greywater; and 6.8, 6.6 and 5.2 in municipal wastewater, respectively. The numbers of TC and E. coli increased when greywater was stored for 24 h at 20 °C but decreased after 96 h. No growth of IE was observed in the greywater. The decay rate experiment showed that viruses and FIB were inactivated relatively rapidly at 20 °C in seawater collected from 1 m depth, while a slow inactivation was observed at 4 °C in seawater collected from 60 m depth, with a significant difference in decay rates (p < .05). Our results suggest that temperature and biological activity may be important factors for the self-purification capacity when wastewater containing faecal bacteria and viruses is discharged to coastal water, and these varying decay rates could be important in risk assessments.

Development of custom assays for the autonomous detection and quantification of human enteric viruses in seawater using Lab on a Chip

Development of custom assays for the autonomous detection and quantification of human enteric viruses in seawater using Lab on a Chip

Transmission of Ostreid herpesvirus-1 microvariant in seawater: Detection of viral DNA in seawater, filter retentates, filter membranes and sentinel Crassostrea gigas spat in upwellers

To understand the transmission of Ostreid herpesvirus-1 microvariant(s) (OsHV-1) in seawater, it is necessary to understand the temporal pattern of occurrence of the virus in seawater in relation to demonstrated infection events in oysters. The aims of the current study were: (1) to investigate the temporal sequence of detection of OsHV-1 in seawater and Crassostrea gigas spat in an upweller system, (2) to assess whether filtration or ageing of seawater reduced the detection of OsHV-1 in seawater and spat, and (3) to assess whether retentate or membranes from filters that were installed to enable continuous sampling of particles in seawater could be used for OsHV-1 surveillance and to investigate OsHV-1 particulate attachment. This study is the first to detect OsHV-1 DNA in 5μm retentates and membranes used to continuously filter natural seawater. OsHV-1 DNA was detected in seawater before it was detected in oysters in 65.4% of the 26 detection events examined across 6 trials in an OsHV-1 endemic estuary. The time of sampling (morning or afternoon) did not affect the detection of OsHV-1 DNA in seawater. Seawater treatment by filtration or ageing did not reduce the frequency of detection of OsHV-1 DNA in seawater. In contrast, the odds of detecting OsHV-1 DNA in the tissues of oysters kept in aged seawater and some filtered seawater treatments were reduced (odds ratios: 0.16–0.36) in comparison to the control. Although OsHV-1 DNA was detected in the retentate from 5μm filtration, it is unlikely these samples will be useful for investigating OsHV-1 particle attachment due to low viral signals. Similarly, OsHV-1 DNA was detected on the 5μm filter membranes, however further investigation is required to ascertain their usefulness in assessing OsHV-1 particle attachment. Despite this and with further development, 5μm filter retentates and filter membranes may prove to be useful samples for the surveillance of OsHV-1 in seawater.

Adsorption of norovirus and ostreid herpesvirus type 1 to polymer membranes for the development of passive samplers.

This study was performed to develop a passive sampling methodology for the detection of two viruses in seawater in the area of shellfish production, the norovirus (NoV), a human pathogen implicated in gastroenteritis outbreaks linked to oyster consumption and the ostreid herpesvirus type 1 (OsHV-1), a virus associated with mass mortalities of Pacific oysters. Commercially, membranes were tested for their capacity to adsorb virus: zetapor, gauze, nylon, low-density polyethylene (LDPE) and polyvinylidene difluoride (PVDF). Laboratory exposures of membranes to contaminated water samples (stool, sewage, seawater) were performed. Our data show that the amount of NoV GII genome per membrane measured with qRT-PCR increased with the time of exposure up to 24h, for all types of membranes except gauze. After 15days of exposure, the amount of NoV GII per membrane continued to increase only for nylon and LDPE. The amount of OsHV-1 per zetapor membrane was significantly increased as soon as 4h ofexposure, and after 24h of exposure for all types of membranes. Exposure of membranes to serial dilutions of various samples revealed that the amount of NoV GII and OsHV-1 per membrane is significantly higher in diluted samples. The detection of NoV and OsHV-1, respectively, with zetapor and PVDF membranes was found to be more efficient than the direct analysis of sewage and seawater. All membranes immersed in contaminated samples adsorbed NoV GII and OsHV-1. The amount of both viruses increased with the time of exposure. Zetapor and PVDF membranes seem to be more adapted to NoV GII and OsHV-1 detection respectively. Membranes tested will be used as passive samplers to improve the detection of virus in oyster production areas. Also, passive samplers could be a valuable tool for microbiome analysis with new generation sequencing.

Surveillance of aquatic animal viruses in seawater and shellfish in Korea

Surveillance of aquatic animal viruses in hosts and seawater is very important to control and prevent the spread of aquatic animal diseases. And also the investigations for shellfish as play role in vector or carrier species, or a candidate host are required. Primer sets for multiplex nested polymerase chain reaction were developed to simultaneously detect aquatic animal viruses (megalocytivirus and white spot syndrome virus as DNA viruses, and viral hemorrhagic septicemia virus, viral nervous necrosis virus [VNNV], and marine birnavirus as RNA viruses) from seawater and shellfish. The multiplex nested PCR amplified each virus specifically with a detection limit of about 10 copies of viral particles and facilitated detection of several aquatic animal viruses from seawater and shellfish. The detection rates of viruses in shellfish samples were not significantly different between areas, except for VNNV which showed much lower positive results in eastern sea area. But, several viruses co-existed in shellfish regardless of the sampling site and time. These results revealed that shellfish might accumulate several viruses over the long-term and could play a role as a bio-indicator or reservoir of viruses derived from aquatic animals. Statement of relevanceThis article is related to field of aquatic animal disease. In this study, we developed multiplex nested PCR assay for detection of aquatic animal viruses from seawater and shellfish. And we found several viruses co-existed in shellfish for long-term, suggesting that shellfish may act as a bio-indicator or reservoir of viruses derived from aquatic animals.

Cell Culture Isolation of Piscine Nodavirus (Betanodavirus) in Fish-Rearing Seawater.

Piscine nodavirus (betanodavirus) is the causative agent of viral nervous necrosis (VNN) in a variety of cultured fish species, particularly marine fish. In the present study, we developed a sensitive method for cell culture isolation of the virus from seawater and applied the method to a spontaneous fish-rearing environment. The virus in seawater was concentrated by an iron-based flocculation method and subjected to isolation with E-11 cells. A real-time reverse transcriptase PCR (RT-PCR) assay was used to quantify the virus in water. After spiking into seawater was performed, a betanodavirus strain (red spotted grouper nervous necrosis virus [RGNNV] genotype) was effectively recovered in the E-11 cells at a detection limit of approximately 10(5)copies (equivalent to 10(2)50% tissue culture infective doses [TCID50])/liter seawater. In an experimental infection of juvenile sevenband grouper (Epinephelus septemfasciatus) with the virus, the virus was isolated from the drainage of a fish-rearing tank when the virus level in water was at least approximately 10(5)copies/liter. The application of this method to seven band grouper-rearing floating net pens, where VNN prevailed, resulted in the successful isolation of the virus from seawater. No differences were found in the partial sequences of the coat protein gene (RNA2) between the clinical virus isolates of dead fish and the cell-cultured virus isolates from seawater, and the viruses were identified as RGNNV. The infection experiment showed that the virus isolates from seawater were virulent to seven band grouper. These results showed direct evidence of the horizontal transmission of betanodavirus via rearing water in marine aquaculture.

A 1-Year Study on the Detection of Human Enteric Viruses in New Caledonia.

Human enteric viruses occur in high concentrations in wastewater and can contaminate receiving environmental waters. Due to the lack of data on the prevalence of enteric viruses in New Caledonia, the presence and the concentrations of enteric viruses in wastewater and seawater were determined. Untreated wastewater and seawater samples were collected monthly for 1 year from a wastewater treatment plant (WWTP) and from the WWTP's outlet, located directly on a popular recreational beach. Samples were tested for norovirus genogroups I and II (NoV GI and GII), astroviruses (AsV), sapoviruses (SaV), enteroviruses (EV), hepatitis A viruses (HAV), rotaviruses (RoV), human adenoviruses (HAdV) and human polyomaviruses (HPyV). To support these data, faecal samples from cases of gastroenteritis were tested for the first time for NoV and detected in the population. NoV GI, NoV GII, EV, SaV, HAdV and HPyV were detected in all wastewaters, RoV in 75% and AsV in 67%. HAV were not detected in wastewater. Overall, 92% of seawater samples were positive for at least one virus. HPyV were detected most frequently in 92% of samples and at concentrations up to 7.7 × 10(3) genome copies/L. NoV GI, NoV GII, EV, SaV, RoV and HAdV were found in 33, 66, 41, 33, 16 and 66% of seawater samples, respectively. AsV were not detected in seawater. This study reports for the first time the presence of NoV and other enteric viruses in New Caledonia and highlights the year-round presence of enteric viruses in the seawater of a popular beach.

Development of red sea bream iridovirus concentration method in seawater by iron flocculation

Pathogen dynamics in environmental water are considered to be highly associated with the prevalence of fish disease. To examine the dynamics of red sea bream iridovirus (RSIV), which has caused serious damage in marine aquacultures in Japan, we developed a highly sensitive and quantitative method by combining the viral concentration and real-time PCR to detect the virus in seawater. The iron flocculation method employed here successfully concentrated 500mL of artificial seawater spiked with RSIV in a 0.1-mL DNA solution at a 5000 concentration magnification, and the recovery rate of the RSIV genome by real-time PCR was higher than 80%. The detection limit of this method was approximately 8.0×101RSIVcopiesL−1 of sample water, which is a more than 1000 times improvement compared to the conventional DNA extraction method without concentration of water sample. Using this method, we detected the RSIV genome from the rearing water for experimentally infected Japanese amberjack Seriola quinqueradiata at ranges from 102.1 to 105.5copiesL−1. The RSIV copy number in the rearing water was increased more than 5days before mortality started and it might become an indicator of disease prediction. These results indicate that the iron flocculation method coupled with PCR detection is useful for monitoring RSIV dynamics in the aquaculture setting. Statement of relevanceMonitoring of RSIV in environmental water.

Measurement of insoluble submicrometer particles and biological materials in seawater to investigate marine aerosol production

The number concentrations of bacteria, viruses, and insoluble submicrometer particles in seawater were simultaneously measured to investigate the effects of biological activity and anthropogenic sources on the number of submicrometer particles in seawater sampled at various coastal locations during different seasons and at varying tidal levels. It was found that when an anthropogenic source was located near a sampling site, there was an increase in the number concentration of insoluble submicrometer particles, as well as enhancements of anthropogenic elements. The concentration of insoluble submicrometer particles was the highest at the Taean site, which had the strongest biological activity. The particle concentration was two to three times higher in spring than in summer or winter, which aligns with the observation that spring had the highest biological activity, which may be caused by the increase in solar radiation and nutrients. During spring tide, when there is maximum tidal variation, strong mixing and the suspension of accumulated sediments can occur. At this time, there were significant increases in the number concentrations of insoluble particles and viruses in seawater. Data suggest that the location, season, and tidal level have great impacts on the biological materials in seawater, which affects the number of insoluble submicrometer particles, and contributes to primary marine aerosols produced by the bubble bursting process.

Simulated sunlight inactivation of norovirus and FRNA bacteriophage in seawater

To investigate norovirus (NoV) and F-specific RNA (FRNA) bacteriophage inactivation in seawater under simulated sunlight and temperature conditions representative of summer (235Wm(-2) ; 17°C) and winter (56Wm(-2) ; 10°C) conditions in Ireland. Inactivation experiments were carried out using a collimated beam of simulated sunlight and 100ml of filtered seawater seeded with virus under controlled temperature conditions. NoV concentrations were determined using RT-qPCR, and FRNA bacteriophage concentrations were determined using RT-qPCR and by plaque assay. For all virus types, the fluence required to achieve a 90% reduction in detectable viruses (S90 value) using RT-qPCR was not significantly different between summer and winter conditions. S90 values for FRNA bacteriophage determined by plaque assay were significantly less than those determined by RT-qPCR. Unlike S90 values determined by RT-qPCR, a significant difference existed between summer and winter S90 values for infectious FRNA bacteriophage. This study demonstrated that RT-qPCR significantly overestimates the survival of infectious virus and is therefore unsuitable for determining the inactivation rates of viruses in seawater. Results from this study provide initial data on the inactivation of NoV and FRNA bacteriophage in seawater under representative summer and winter conditions and will be of interest to shellfish and water management agencies alike.