Quality Of Shellfish Research Articles

Risk valuation for E. coli contamination in Campania region shellfish from 2016 to 2021

This study set out to assess the microbiological quality of shellfish collected over a six-year period of time in the Campania Region Sea. A total of 1459 samples were examined in order to determine whether Escherichia coli was present. To investigate potential correlations between the E. coli counts and environmental parameters (salinity, pH, dissolved oxygen, seawater temperature, turbidity, rainfall) and pollution variables (density and distance of heavy and light discharges), data were gathered. With only roughly 19% of the samples not meeting European and Italian criteria (E. coli counts more than 230 most likely number MPN per 100 g of pulp and intravalvar liquid), the results showed that the microbiological quality of the shellfish was good.A correlation between microbial contamination, season, rainfall, and dissolved oxygen was found using statistical analysis. However, the discharge density along the coast per spatial unit (a 200 × 200 MT cell), which was determined using the "quartic" Kernel function, showed found to be the primary factor determining the E. coli concentration in the shellfish.An increase in rain millimeters was found to be associated with a higher risk of heightened E. coli contamination, according to a model that was fitted to assess the probability of detecting a higher E. coli count in connection to environmental parameters. This outcome could be explained by the discharge density near the coast as well as the increased availability of coliforms, particularly E. coli, and nutrients during periods of heavier rainfall.

Effects of culinary treatments on the lipid nutritional quality of fish and shellfish.

Coronary heart disease (CHD) is one of the leading causes of death worldwide. Seafood, especially fish and shellfish, is a healthy food that reduces the risk of CHD. In many regions, seafood is consumed cooked to eliminate potentially pathogenic microorganisms. Although there have been many reports of culinary preparations causing changes in the fatty acid profile of fish and shellfish, this information has not been well organized, and most of it is not associated to CHD. Therefore, this study was conducted to study the effect of culinary treatments of seafood on lipid nutritional quality in relation to promotion/prevention of CHD. In this study, fatty acid profiles of fish and shellfish prepared with different culinary preparations were obtained from published literature. Lipid nutritional quality indices related to promoting/preventing CHD were calculated and analyzed to reveal the effects of culinary treatment on the lipid nutritional quality of fish and shellfish in promoting/preventing of CHD. The information in this article is very useful and can fill the knowledge gap of the effects of culinary preparation on the lipid nutritional quality of fish and shellfish. Such information is very useful for guiding consumers to choose better ways to cook fish and shellfish to reduce the risk of CHD.

Quality Assessment of Litopenaeus Vannamei Shrimp

This study aimed to throw the light on the nutritional value and quality of shell fish in addition to knowing the incipient spoilage of shellfish through definition of , evaluation of chemical composition of Litopenaeus vannamei shrimp (Total protein, Total fat, Total fiber, Humidity and ash), chemical analysis of Litopenaeus vannamei shrimp to determine its quality (pH, TVN, TBA and FFA) and evaluation of Litopenaeus vannamei shrimp quality. The study was carried-out on Shrimp samples from Berkeit Ghalioun, Kafr El-Sheikh Governorate, Egypt. The samples was collected during the summer season of 2022. All samples were transported directly fresh to laboratory in ice box (at 5 – 10 oC), within 2 – 3 hours for examination. The collected 70 shrimp (30 shrimp fresh and 40 shrimp frozen) were examined for sensory and biochemical evaluation at different periods of the study. The bacteriological evaluation was made on fresh (30 samples at different densities 100 m2 and 200 m2 of breeding) and the 70 frozen samples. This study concluded that, the sensory evaluation characters that includes colour, head/chest and tail , legs, shell and tentacles , eyes, dour and meat cleared that, the shrimp during its storage period that ranged from 1 to 20 days , the shrimp in agood quality conditions where its quantitative score ranged from 10 to 1 for the storage shrimp at 1 and 20 day. While, the results of constituent evaluation that includes protein %, fat %, moisture %, ash %, and the product evaluations that includes TBA %, TVBN %, pH, decreased with increasing the period of storage from 0 to 72 hours, while, the level of bacterial count (Total viable count, enterobacteriacae, coliforms, total staphylococci and staph. aureus counts increased with increasing the period of storage. Good preservation and application of good hygiene principlrs during catching improved the quality of shrimp.

Detection and Molecular Characterization of Enteric Viruses in Bivalve Mollusks Collected in Arraial do Cabo, Rio de Janeiro, Brazil.

Viral bivalve contamination is a recognized food safety hazard. Therefore, this study investigated the detection rates, seasonality, quantification, and genetic diversity of enteric viruses in bivalve samples (mussels and oysters). We collected 97 shellfish samples between March 2018 and February 2020. The screening of samples by qPCR or RT-qPCR revealed the detection of norovirus (42.3%), rotavirus A (RVA; 16.5%), human adenovirus (HAdV; 24.7%), and human bocavirus (HBoV; 13.4%). There was no detection of hepatitis A virus. In total, 58.8% of shellfish samples tested positive for one or more viruses, with 42.1% of positive samples contaminated with two or more viruses. Norovirus showed the highest median viral load (3.3 × 106 GC/g), followed by HAdV (median of 3.5 × 104 GC/g), RVA (median of 1.5 × 103 GC/g), and HBoV (median of 1.3 × 103 GC/g). Phylogenetic analysis revealed that norovirus strains belonged to genotype GII.12[P16], RVA to genotype I2, HAdV to types -C2, -C5, and -F40, and HBoV to genotypes -1 and -2. Our results demonstrate the viral contamination of bivalves, emphasizing the need for virological monitoring programs to ensure the quality and safety of shellfish for human consumption and as a valuable surveillance tool to monitor emerging viruses and novel variants.

Analysis of volatile components changes of Ruditapes philippinarum during boiling by HS-GC-IMS coupled with multivariate analyses

Boiling is an effective way to enhance the shellfish flavor. Headspace-Gas Chromatography-Ion Mobility Spectrum (HS-GC-IMS) coupled with multivariate analyses was applied to illustrate the effect of boiling on volatile organic compounds (VOCs) of Ruditapes philippinarum. Quantitative descriptive analysis (QDA) was applied to evaluate the aroma profile of Ruditapes philippinarum during boiling. The correlation between VOCs and aroma properties of Ruditapes philippinarum was also built through partial least-squares regression (PLSR) model. In this study, the flavor fingerprint was built to distinguish raw and different boiled samples through HS-GC-IMS. The 62 VOCs were totally identified, including 21 alcohols, 10 aldehydes, 10 ketones, 9 esters and 4 sulfur-containing compounds. Boiling significantly enhanced the pleasant seafood-like aroma by producing esters and reduced the sea sand-like aroma by decreasing the concentration of sulfur-containing compounds. The 10–15 min was the transitional stage for producing flavor, while heating over 20 min produced more unpleasant odorants. These results indicated that boiling was vital to improve the flavor quality of shellfish.

Microbial diversity and nutritional profile of processed and unprocessed Tympanotonus fuscatus (Periwinkle), Crassostrea gasar (Oyster) and Rapana venosa (Whelk)

A study of the microbiological quality and proximate composition of Shellfish purchased from different markets in Rivers State. The results obtained for raw and cooked shellfish are as follows: Total Viable Bacteria Count ranged from Log10 cfu/g 3.39 -7.74, Total Salmonella Count ranged Log10 cfu/g 1.5-6.47, Total Staphylococcus Count; Log10 cfu/g 3.07 -5.58, Total Vibrio Count Log10 cfu/g0 cfu/g 0.2 – 4.3. Most samples analyzed did not meet ICMSF standards for raw and cooked samples. Twelve bacteria species were isolated from raw(unprocessed) and processed periwinkle, oyster and whelk; Salmonella sp, Proteus sp, Escherichia coli, Micrococcus sp, Vibrio cholerea, Vibrio parahaemolyticus, Enterobacter sp, Klebsiella sp, Citrobacter sp, Staphylococcus sp, Bacillus sp and Pseudomonas sp. Proximate analysis showed that cooking does minimal to insignificant damage to the nutrient content in the sea foods. Handling and consumption of seafood must be undertaken carefully and knowledgeably to avoid food borne infections.

Comparative study on the esterification of gymnodimine in different shellfish exposed to the dissolved toxin in seawater

Some lipophilic phycotoxins dissolved in seawater can be accumulated by bivalves via the filtering process. To explore the relationship between the bioaccumulation of gymnodimine-A (GYM-A) and free fatty acids (FFAs) of shellfish, three species of bivalves (venus clam Meretrix meretrix, mussel Mytilus galloprovincialis, and ark shell Anadara kagoshimensis) were exposed to dissolved GYM-A for 7 days in the same seawater system. Results indicated that GYM-A can be accumulated by these bivalves from the dissolved phase and esterified with FFAs reaching over 90% in most tissues of bivalves. Gymnodimine-A and its esters mainly distributed in the gills of shellfish, and the highest concentration of toxins occurred in mussel, followed by ark shell and venus clam. Similar percent of different fatty acid esters occurred in the experimental shellfish, in which the C16:0, C17:0, C18:0, C18:1, C20:1, C20:2, C22:2, and C22:6-GYM-A esters were the main metabolites of GYM-A. The binding capacity of fatty acids and GYM-A varied in different FFAs, which can explain why the C20:1-GYM-A ester dominated the ester profile while C16:0 was the most abundant fatty acid in all samples. Comparing with the FFA profile of shellfish in the control groups, overexpression of some FFAs occurred in the tissues of shellfish exposed to GYM-A in the experimental groups, which suggested that biosynthesis of FFAs was affected by the accumulation and metabolism of GYM-A in bivalves. Multiple fatty acids including some valuably nutritional FFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were consumed in the esterification metabolism of GYM-A, which hinted that the lipid metabolism and nutritional quality of shellfish affected by the contamination of GYMs should be explored and assessed in future works.

Investigating the biochemical effects of heat stress and sample quenching approach on the metabolic profiling of abalone (Haliotis iris).

Ocean temperatures have been consistently increasing due to climate change, and the frequency of heatwave events on shellfish quality is a growing concern worldwide. Typically, shellfish growing areas are in remote or difficult to access locations which makes in-field sampling and sample preservation of shellfish heat stress difficult. As such, there is a need to investigate in-field sampling approaches that facilitate the study of heat stress in shellfish. This study aims to apply a gas chromatography-mass spectrometry (GC-MS) based metabolomics approach to examine molecular mechanisms of heat stress responses in shellfish using abalone as a model, and compare the effects of different quenching protocols on abalone metabolic profiles. Twenty adult Haliotis iris abalone were exposed to two temperatures (14°C and 24°C) for 24h. Then, haemolymph and muscle tissues of each animal were sampled and quenched with 4 different protocols (liquid nitrogen, dry ice, cold methanol solution and normal ice) which were analyzed via GC-MS for central carbon metabolites. The effects of different quenching protocols were only observed in muscle tissues in which the cold methanol solution and normal ice caused some changes in the observed metabolic profiles, compared to dry ice and liquid nitrogen. Abalone muscle tissues were less affected by thermal stress than haemolymph. There were 10 and 46 compounds significantly influenced by thermal stress in muscle and haemolymph, respectively. The changes of these metabolite signatures indicate oxidative damage, disturbance of amino acid and fatty acid metabolism, and a shift from aerobic metabolism to anaerobic pathways. The study provided insights into the heat response of abalone, which could be useful for understanding the effects of marine heatwaves and summer mortality events on abalone. Dry ice appeared to be a suitable protocol, and safer in-field alternative to liquid nitrogen, for quenching of abalone tissues.

Factors Affecting Shellfish Quality in Terms of Faecal Contamination at Blakeney Point, East Anglia, UK

Relatively high E. coli and Faecal Streptococci (FS) numbers have been reported in the waters surrounding Blakeney Point, East Anglia, UK, an area containing significant shellfishery industries including mussels and cockles, despite the implementation of development works aimed at reducing residual contamination problems. The aim of this study was to evaluate the potential of using bacterial analyses and sterol profiling to assess the current levels and source of faecal pollution at Blakeney Point. No evidence of significant human faecal contamination of water in and around Blakeney Point could be found using either traditional microbiological analyses or sterol profile analysis. The presence of significant quantities of sitosterol, however, suggests that faecal contamination of water from birds does occur but at the concentration detected would not affect water quality. Analysis of cockles and mussels taken from the area show that negligible levels of coprostanol were present, confirming that faecal pollution was not causing any contamination issues. Apart from cholesterol, brassicasterol, an algal biomarker, as expected was dominant in shellfish flesh. The results confirm that current water treatment processes are successful in ensuring water quality at Blakeney Point and that a combination of microbial testing with sterol profile analysis confirmed that low microbial concentrations of faecal contaminants present in and around Blakeney Point most probably originate from migratory and/or resident bird species.

Polycyclic aromatic hydrocarbons in sediments and shellfish from Todos os Santos bay, Brazil

The present study evaluated the occurrence of 24 Polycyclic Aromatic Hydrocarbons (PAHs) in sediments and shellfish (Anomalocardia flexuosa, Crassostrea rhizophorae, and Mytella guyanensis) of Todos os Santos bay (BTS, Brazil). Total PAHs levels ranged from 89 to 921 ng g-1 dry weight (d.w.) in sediments, and from 66 to 505 ng g-1 d.w. in shellfish, signalizing that BTS was moderately contaminated by PAHs, mostly from pyrogenic activities. The bioaccumulation factor (BAF) of total PAHs ranged from 0.20 to 2.9 and did not show a clear trend among the studied species. BAFs of high molecular weight compounds were higher for A. flexuosa (specie found buried in fine sediment), while those of low molecular weight compounds were higher for C. rhizophorae (specie found in the roots of mangrove trees). High concentrations of PAHs, especially benzo[a]pyrene and dibenzo[a,h]anthracene, suggest that contamination compromises shellfish quality and raise concern about seafood consumption safety.

Shellfish consumption and recreational gathering practices in Northland, New Zealand

Shellfish are a popular food with high cultural, economic and nutritional importance in New Zealand but may also be a significant pathway of human exposure to contaminants. Currently, limited data on shellfish consumption rates in New Zealand poses challenges for risk assessment. This study investigated the rate of shellfish consumption and recreational gathering practices in Northland using a self-completed parallel mixed methodology survey. Seventy six percent (n=229) of total survey respondents (n=302) reported consuming shellfish, with an average daily consumption of 4.8 g.day−1. Consumption of cooked shellfish was preferred over raw shellfish. Seventy-two percent of shellfish consumers (n=166) reported eating recreationally gathered shellfish, with on average 48% of shellfish consumed gathered recreationally. While the key motivation for gathering was enjoyment, providing food was also of great importance. When selecting gathering places respondents prioritised proximity and shellfish quantity over shellfish quality, reporting limited and geographically close gathering sites. In general, the quality of shellfish was perceived to be high, and unchanged, although a minority of respondents reported a perceived decline in the quality due to over gathering. Ethnicity was the main parameter influencing shellfish consumption whereas age and gender influenced shellfish gathering.

Occurrence of Human Enteric Viruses in Shellfish along the Production and Distribution Chain in Sicily, Italy.

Contamination of bivalve mollusks with human pathogenic viruses represents a recognized food safety risk. Thus, monitoring programs for shellfish quality along the entire food chain could help to finally preserve the health of consumers. The aim of the present study was to provide up-to-date data on the prevalence of enteric virus contamination along the shellfish production and distribution chain in Sicily. To this end, 162 batches of mollusks were collected between 2017 and 2019 from harvesting areas, depuration and dispatch centers (n = 63), restaurants (n = 6) and retail stores (n = 93) distributed all over the island. Samples were processed according to ISO 15216 standard method, and the presence of genogroup GI and GII norovirus (NoV), hepatitis A and E viruses (HAV, HEV), rotavirus and adenovirus was investigated by real-time reverse transcription polymerase chain reaction (real-time-RT PCR), nested (RT)-PCR and molecular genotyping. Our findings show that 5.56% of samples were contaminated with at least one NoV, HAV and/or HEV. Contaminated shellfish were sampled at production sites and retail stores and their origin was traced back to Spain and several municipalities in Italy. In conclusion, our study highlights the need to implement routine monitoring programs along the whole food chain as an effective measure to prevent foodborne transmission of enteric viruses.

Effects of curcumin‐based photodynamic method on protein degradation of oysters

SummaryPhotodynamic treatment (PDT) is a novel cold‐sterilisation technology, but the evaluation of the protein quality of shellfish was scarce. In this study, the effects of curcumin (CUR)‐mediated PDT on delaying protein degradation of oysters during cold storage at 4 ℃ and the mechanisms were investigated. The protein‐degradation indexes and related enzymes were determined every 2 days. The results showed that the content of total volatile basic nitrogen (TVB‐N), polypeptide nitrogen (PeN), amino acid nitrogen (AN) and free amino acid (FAA) in photodynamic group was significantly different from the control group since the first 2 days (P < 0.05). The pH value was significantly changed by PDT at the 4th and 8th day (P < 0.05). Interestingly, the activities of serine and aspartic protease were significantly inhibited by PDT during the whole cold storage (P < 0.05). Therefore, the study indicated that PDT has a positive effect on preventing protein degradation.

Consumers’ Perceptions of Bivalve Shellfish Quality and Safety among Niger Delta Population

Bivalve shellfish is a delicious and healthy diet in coastal cities around the world. They are important food items in several dietary regimes in the Niger delta. This study investigated consumers’ perceptions of quality and safety of bivalve shellfish among populations along Niger delta coastline. A clustered based sampling procedure was applied to carry out consumer survey on bivalve shellfish perceptions of quality and safety at four locations along the Atlantic coastline of Niger delta. This was carried out through the use open questionnaire administered through direct interview. Results showed a significant relationship (p<0.05) between some socio-economic attributes and perceptions toward bivalve shellfish consumption. A strong effects of these variables on perception towards bivalve was observed in mean scores of the determined variables. All bivalve species were adjudged to be easily available and cheap implying that bivalve shellfish is a low priced product. Bivalve consumers were conscious of the effects of environmental pollution on the product quality and safety but do not make it a pre-condition before purchasing the product. Over 22% of the consumers have experienced negative health related conditions such as stomach ache, diarrhea and vomiting which were attributed to bivalve consumption. The culinary tradition of consuming bivalve shellfish fresh or slightly cooked raised serious concerned about their safety and tendency to increase risks to consumers’ health. This survey would avail stakeholders in bivalve shellfish related businesses with adequate knowledge on the safety and possible source of risk to consumers

Biochemical composition and biometric parameters of Mytilus galloprovincialis from Boka Kotorska Bay in Southern Adriatic Sea

This study reports, for the first time, different physico-chemical analyses, of Mediterranean mussels (Mytilus galloprovincialis) from harvesting areas in the Montenegro coast of the Adriatic Sea, in order to evaluate the influence of origin on different parameters and assessed the quality of shellfish grown in this area. The Boka Kotorska Bay is situated in Montenegro, in the south-eastern part of the Adriatic Sea The mussel samples were collected at the same time in the spring of 2019 at six locations in Boka Kotorska Bay, Montenegro: Kotor and Tivat Bays. Biometric parameters, percentage of meat, condition index, proximate composition, sensory evaluation and lipid profiles of mussels were studied. The concentrations of some micro and macro elements and heavy metals in mussels, were also analyzed. Significant differences were found between mussels from different locations. Mean biometric parameters of mussels grown in Sv.Nedjelja, were considerably higher than in mussels grown elsewhere.. Protein, lipid, ash and glycogen content were varied from 7.80 to 10.26%; 1.36 to 2.18%; 1.73 to 3.34% and 12.81 to 15.38%, respectively. Gas chromatographic analysis showed that polyunsaturated fatty acids (PUFAs) were dominant lipids in mussels (37.56 to 41.08%), followed by monounsaturated (MUFAs) (30.52 to 38.31%) and saturated (SFAs) (21.89 to 29.45%) fatty acids. Fatty acid profiles were investigated and revealed high contents of n-3 PUFAs and high n-3/n-6 ratios in all mussels from Montenegro In the mussel samples high concentrations of K, Mg, Ca, and Na, and much lower concentrations of Fe, Mn, Zn, and Cu were found. Some of toxic elements (As, Pb, Hg and Cd) were determined also.. The qualitative sensory assessment showed that all mussels were acceptable. All mussels in the current study achieved scores of 3 or more out of 5 in the qualitative category. Data on biochemical composition and quality indices of the mussels cultured in the Boka Kotorska Bay demonstrated that these products could be accepted well by consumers and could compete with other currently available mussels from other locations in Adriatic Sea.

Microbiological quality of shellfish and evaluation of compact dry EC for detecting total coliforms and Escherichia coli

The objective of this study was to evaluate the microbiological quality of oysters and mussels grown in Cananéia, Brazil, by analysing mesophiles, psychrothophic bacteria, moulds and yeasts, Staphylococcus aureus, and Salmonella spp., and to compare the efficiency of Compact Dry EC method and the conventional method for counting of total coliforms and Escherichia coli. The microbial analysis showed that the mean values of mesophilic counts were 3.14±0.81 log CFU g−1 for oysters and 3.92±0.90 for mussels; the mean values of psychrophilic counts were 2.78±0.75 log CFU g−1 for oysters and 3.22±0.75 log CFU g−1 for mussels; the mean values of mould and yeast counts were 3.70±0.58 log CFU g−1 for oysters and 3.33±0.81 log CFU g−1 for mussels. Salmonella spp. did not present positive results, and the maximal count of Staphylococcus aureus was 1.7 log CFU g−1, therefore, within the limits established in the legislation. The correlation coefficients between the Compact Dry EC method and conventional method were >0.87 for total coliform and E. coli counts for both types of shellfish. The data in this study show that the Compact Dry EC method is an acceptable alternative to conventional methods for enumeration of total coliforms and E. coli in shellfish.

Evaluation on Frozen Shellfish Quality by Blockchain Based Multi-Sensors Monitoring and SVM Algorithm During Cold Storage

IoT-enable monitoring can provide valuable information for the shellfish quality evaluation during cold storage condition. However, IoT based information storage relies on the centralized platform, it is possible to tamper. In this paper, we establish blockchain based multi-sensors (WSN) monitoring system to collect quality parameters and verify captured information for improving transparency and trust during cold storage. The implementation of the K-means and SVM algorithms were used in quality evaluation applications to classify and predict the quality loss of frozen shellfish. The results show blockchain based WSN monitoring can achieve the dynamic indicators continuous monitoring and ensures the data security and reliability. The proportion of the training set and the test set in the allowable deviation range is 88.89% and 87.17%. The root mean square error (RMSE) of training set and test set are 0.1502 and 0.1793 by SVM model. The performance of the K-means and SVM model has higher accuracy than BP model. This paper could help to reduce the risk of food losses and improve quality and safety management of frozen shellfish during cold storage.

Effects of Chlorella sp. Additions on the Changes of Visceral Mass and Proximate Contents of Shellfish

Shellfish, called as kerang in Indonesia, contains animal protein that’s popular, making it as and important fisheries and marine commodity. Supported by the good taste and high nutrient content in it. Paphia undulata or Kerang Batik, Peryglipta reticulata or Kerang Kemiri, Meretrix meretrix or Kerang Tahu, and Codakia tigerina or Kerang Madu, are consumption shells from northern coast of Java. To improve the quality of shellfish, Chlorella added as shellfish food preferences. It supported by the high nutrient content in Chlorella sp. Shellfish kept for 15 days in a basket with a sand substrate and drainage from sea. Therefore, the water quality had been controlled for the changed of salinity and water temperature. Parameters used to see the improvement shellfish quality is the color changes on visceral mass and the changes of proximate content (moisture, protein, fat, carbohydrate and ash). This study proves the color changes on visceral mass and proximate content. The color change occurs on the visceral mass and the gills. The changes of viscerall mass occurs on kerang batik from white greyish to yellow while the more clearly gills occurs on kerang madu and kemiri. Meanwhile, the change of proximate shown by the increasing of protein and moisture on all the spesies while on the otherside the decreasing of carbohydrate and ash, but the increasing of fat only occurs on kerang batik and kerang madu. The higher proximate changes occur on kerang madu, where the ammount of moisture at 71,43 ± 0,03 %, the protein at 16,55 ± 0,02 %, the fat at 1,35 ± 0,04 %, the carbohydrate at 2,9 ± 0,03 %, and the ash at 8,09 ± 0,04 %. The conclusion of this research are kerang madu has the higher positive influences by addition of Chlorella, shown by the increasing of proximate contents and the clearly of gills. Keywords : addision of Chlorella sp., changes of visceral mass, proximate, shellfish

Microbial quality of wild shellfish in a tropical estuary subject to treated effluent discharge

Elevated faecal indicator levels in beaches around Darwin Harbour including near effluent outfalls have led to concerns about the safety of popular, locally harvested aquatic foods. To address these concerns, the impact of treated effluent discharge on the microbial quality of aquatic foods was assessed using culture-based and molecular tools.Seawater, shellfish (mangrove snails Telescopium and Nerita balteata, the local black lip oyster Saccostrea cucullata) and mud crabs (Scylla serrata) were collected from 13 sites close (impacted) and distal (reference) to two effluent discharge locations, in creeks and coastal areas. Sampling occurred over two dry seasons and one wet season.E. coli, typical sewage related pathogens, Salmonella and norovirus, and the molecular faecal marker Bacteroides, as well as naturally occurring marine bacteria, Vibrio parahaemolyticus and Vibrio vulnificus were tested in biota. E. coli and faecal coliforms were measured in water in water.The highest concentration of faecal coliforms in water was from the Buffalo Creek discharge site. At sites located in creeks including reference creeks, the highest concentrations of faecal coliforms in water were measured in the wet season compared to the dry season, whereas in coastal sites, no or only few (<10) faecal coliforms were detected.E. coli concentrations in both snail species were significantly higher in the wet season compared to the dry season (P < 0.0001) at both the treated effluent discharge sites and reference sites with some samples exceeding the acceptable Australian and New Zealand Food Standards (ANZFS) level based on E. coli levels in bivalves.E. coli concentrations in all of the S. cucullata samples were either below the detection limit or below the ANZFS limit for E. coli. No E. coli exceedances occurred in cooked mud crabs although low E. coli levels were measured in 3 cooked mud crab samples.Only one shellfish sample (T. telescopium) was positive for Salmonella. Norovirus and Bacteroides were not detected in any of the shellfish samples tested.V. parahaemolyticus and V. vulnificus were significantly more prevalent in shellfish samples during the wet season. Twelve virulent strains of V. parahaemolyticus were detected in T. telescopium and two in N. balteata. There was no significant difference in V. parahaemolyticus prevalence between sites. V. parahaemolyticus was detected in cooked S. serrata samples from three sites in the wet season and once in the 2016 dry season.V. vulnificus was detected in both T. telescopium and N. balteata, but not in any of the S. cucullata samples. One cooked crab meat sample from a reference site was positive for V. vulnificus. The prevalence of V. vulnificus was significantly higher at the reference sites compared to the discharge or potential impact sites.The lack of correlation between E. coli and targeted faecal pathogens in biota confirm that traditional faecal markers are not suitable surrogates for faecal pollution, at least not in the tropics.The higher prevalence of E. coli, V. parahaemolyticus and V. vulnificus in biota during the wet season compared to the dry season irrespective of treated sewage influence suggests that marine snails should not be harvested and consumed from creeks during the wet season. Any future aquaculture involving shellfish should consider these data when developing appropriate shellfish quality assurance protocols and for making decisions on where to situate farms.

Current and Emerging Technologies for the Detection of Norovirus from Shellfish.

Reports of norovirus infections associated with the consumption of contaminated bivalve molluscan shellfish negatively impact both consumers and commercial shellfish operators. Current virus recovery and PCR detection methods can be expensive and time consuming. Due to the lack of rapid, user-friendly and onsite/infield methods, it has been difficult to establish an effective virus monitoring regime that is able to identify contamination points across the production line (i.e., farm-to-plate) to ensure shellfish quality. The focus of this review is to evaluate current norovirus detection methods and discuss emerging approaches. Recent advances in omics-based detection approaches have the potential to identify novel biomarkers that can be incorporated into rapid detection kits for onsite use. Furthermore, some omics techniques have the potential to simultaneously detect multiple enteric viruses that cause human disease. Other emerging technologies discussed include microfluidic, aptamer and biosensor-based detection methods developed to detect norovirus with high sensitivity from a simple matrix. Many of these approaches have the potential to be developed as user-friendly onsite detection kits with minimal costs. However, more collaborative efforts on research and development will be required to commercialize such products. Once developed, these emerging technologies could provide a way forward that minimizes public health risks associated with shellfish consumption.