Modification of gel properties of Meretrix meretrix (clam) with polysaccharides: physical characterization and interaction mechanism.

BACKGROUND: This study investigated the contribution of 11 polysaccharides (2%, w/w), including pectin (PC), κ-carrageenan (KC), ι-carrageenan (IC), gellan gum (GG), guar gum (GM), sodium alginate (SA), konjac gum (KG), gum arabic (GA), fucoidan (FC), locust bean gum (LBG), and curdlan (CD), to the gel and microstructural properties of Meretrix meretrix clam gel (MMG). RESULTS: The hardness, springiness and chewiness of MMG with KC, IC, GG, SA and FC addition increased by ~10%-250%, while PC, GM, KG and LBG groups decreased by ~0.6% to 69%. KC, IC, SA, GG and FC decreased the cooking loss rate (CLR) by 69.4% to 88.7% and correspondingly enhanced the water holding capacity (WHC) by 10.2% to 21.4%, which was accompanied by an increased bound water and immobilized water area and high hydrogen proton density. The addition of KC transformed the MMG microstructure from a loose network with large pores to a compact, dense network, reducing lacunarity by 57.9%. The primary intermolecular forces in MMG with the incorporation of KC, IC, GG, SA and FC were hydrophobic interactions and disulfide bonds, which increased by 32.8%-105.3% and 45.6%-114.5% than MMG alone, respectively. CONCLUSION: Collectively, KC, IC, GG, SA and FC could improve the gel properties of MMG and the strongest synergistic combination was found in the MMG/KC system. This study suggests that the incorporation of polysaccharides is a strategy with potential for modifying the gel properties of shellfish surimi products. © 2024 Society of Chemical Industry.

Addition of mussel shells enhance marine benthic biodiversity in two degraded coastal soft sediment ecosystems.

The decline in coastal shellfish populations, attributed to anthropogenic stressors such as harvesting via dredging, can deplete the seabed of vital biogenic habitat. This removal of shellfish significantly reduces habitat complexity, biodiversity, and the hard substrate required for the natural recovery of some key species. A common method for oyster restoration involves deploying oyster shell material to provide habitat and substrate for settling larval oysters. In contrast, hard substrate is not required for the mussel lifecycle and as a result the deployment of mussel shell for seabed restoration has received minimal attention, with the effects of reintroducing this material poorly understood. Deploying mussel shell material has the potential to aid in ecosystem recovery, including reviving seabed biodiversity, especially in areas that have been depleted of shellfish via damaging methods such as dredging. This study aimed to investigate the ecosystem effects of returning mussel shells onto two locations with differing soft sediment (sand and mud) in areas historically subjected to excessive dredging of mussel populations and sedimentation. Within 2 years 4 months the infaunal taxa richness was higher in the shell areas compared to the reference areas in both locations, while abundance of infauna was higher in only the sand location and infaunal diversity did not differ at either location. Epifaunal diversity was also higher in the shell area compared to the reference areas at both locations, while the abundance and richness did not differ. Few significant differences were seen in benthic biogeochemical variables between the reference and shell areas and those observed were likely the result of the addition of the shell material changing the sediment composition. These findings demonstrate that mussel shells are a restoration tool that can enhance epifaunal biodiversity and infaunal taxa richness in soft sediment ecosystems historically impacted by shellfish overharvesting and sedimentation.

Paralytic Shellfish Toxin Extraction from Bivalve Meat for Analysis Using Potentiometric Chemical Sensors.

A simple and reliable methodology for the detection of paralytic shellfish toxins (PSTs) in bivalve tissues using potentiometric chemical sensors was developed. Five methods of PST extraction from mussel and oyster tissues were evaluated, including the AOAC-recommended method, which served as the reference. The main objective was to minimize the matrix effect of the extracts on the sensors' responses and ensure efficient toxin recovery. Extraction procedures using acetic acid with heating and water yielded the highest responses from the potentiometric chemical sensors to PSTs. The highest recovery of PSTs from bivalve tissues was achieved with extraction using acetic acid and heating. Further extract purification, which is indispensable for liquid chromatography with fluorometric detection (LC-FLD) analysis, was found to be unnecessary for analysis with chemical sensors. While water extraction can also be used as a rapid and simple PST extraction method, the lower recoveries should be considered when interpreting the results. Further research is needed to identify the compounds remaining in the extracts that cause a decrease in sensor responses and to develop procedures for their elimination.

Investigating Non-Native Ribbon Worm Cephalothrix simula as a Potential Source of Tetrodotoxin in British Bivalve Shellfish.

Tetrodotoxin (TTX) is a potent marine neurotoxin found in several phylogenetically diverse organisms, some of which are sought as seafood. Since 2015, TTX has been reported in bivalve shellfish from several estuarine locations along the Mediterranean and European Atlantic coasts, posing an emerging food safety concern. Although reports on spatial and temporal distribution have increased in recent years, processes leading to TTX accumulation in European bivalves are yet to be described. Here, we explored the hypothesis that the ribbon worm species Cephalothrix simula, known to contain high levels of TTX, could play a role in the trophic transfer of the toxin into shellfish. During a field study at a single location in southern England, we confirmed C. simula DNA in seawater adjacent to trestle-farmed Pacific oysters Magallana gigas (formerly Crassostrea gigas) with a history of TTX occurrence. C. simula DNA in seawater was significantly higher in June and July during the active phase of toxin accumulation compared to periods of either no or continually decreasing TTX concentrations in M. gigas. In addition, C. simula DNA was detected in oyster digestive glands collected on 15 June 2021, the day with the highest recorded C. simula DNA abundance in seawater. These findings show evidence of a relationship between C. simula and TTX occurrence, providing support for the hypothesis that bivalves may acquire TTX through filter-feeding on microscopic life forms of C. simula present in the water column at particular periods each year. Although further evidence is needed to confirm such feeding activity, this study significantly contributes to discussions about the biological source of TTX in European bivalve shellfish.

Lipophilic marine toxins in sediments from Arrábida marine protected area, Portugal (NE Atlantic).

During the development and senescence of harmful algal blooms (HAB), most of the algae cells not ingested by grazers or filter-feeding organisms sink to the bottom, making sediments important reservoirs of algae toxins. In this study, lipophilic marine toxins were determined in the sediments collected from depths ranging from 5 to 145 m depth in the marine protected area of Arrábida (southwest Portuguese coast). Sediments were characterized in terms of granulometry, water and organic matter content. The toxins were determined by liquid chromatography with tandem mass spectrometry. Okadaic acid (OA), dinophysistoxin-2 (DTX2), and azaspiracid-2 (AZA2), reaching concentrations up to 3.4, 1.3, and 0.13 ng/g, respectively, were found. A trend in the occurrence of DTX2 and AZA2 with sediment water and organic matter content was observed, as well as with AZA2 and depth. This study highlights the need to further investigate sediment deposition of toxins and their availability for bottom-dwelling organisms and its contamination.

Unraveling the risks of nAl2O3 on harmful algal blooms: Insights from paralytic shellfish toxins production of Alexandrium tamarense.

As one of the commonly used and cost-effective nanomaterials, nanosized aluminum oxide (nAl2O3) posses unique properties and chemical stability. However, its extensive use and resultant dissemination into aquatic ecosystems prompt concerns over the proliferation and repercussions of harmful algal blooms, particularly those caused by dinoflagellates producing toxins. This study investigated the sub-chronic effects of nAl2O3 on growth, physiological activities, and paralytic shellfish toxins (PSTs) production in Alexandrium tamarense. Results showed dose-dependent inhibition in growth (EC50 = 20.6 mg L-1), esterase activity, and photosynthetic efficiency (Fv/Fm) during the sub-chronic exposure (13-day). The internalization of nAl2O3 in microalgal cells and the significant decrease in the total cellular PSTs content were observed under high nAl2O3 concentrations (>40 mg L-1). The study also demonstrated a clear decrease in the content of some derivatives of PSTs (GTX5, C1/2, and GTX2/3) with the increase in nAl2O3 concentrations, accompanied by the induction of an unknown derivative. Excessive ROS production, dissolved Al, and physical inhibition were suggested as potential mechanisms for nAl2O3 toxicity and changes in PSTs toxin profile. Overall, this research enhances our understanding of the potentiated risks and threats on the possible concurrent events of toxic dinoflagellate, such as Alexandrium species and nanoparticles in aquatic environments.

The effects of Mid-Holocene foragers on the European oyster in Denmark.

Oysters (Ostreidae) play a pivotal role in the health and productivity of marine ecosystems. Their unique ability to filter water, provide habitat, and contribute to nutrient cycling has remained underused in many parts of Europe following the destruction of vast oyster beds in the 19th and 20th centuries. The burgeoning field of oyster restoration for aquaculture has recognized the potential of these bivalves in promoting ecosystem resilience and enhancing biodiversity. Restoring oysters to previous levels requires the establishment of ecological baselines that ideally take into account the long-term changes of animal behavior as well as the surrounding environment prior to significant human intervention, an extremely challenging task. Archaeological shell middens are invaluable baseline archives and provide exclusive insights into past ecosystems. Here, we use demographic information from over 2,000 analyzed European oyster (Ostrea edulis) shells dating from ~5,660 to 2,600 cal BCE (calibrated years BCE), the largest archaeological growth rate dataset of mollusks yet. Through the analysis of size as well as ontogenetic age, we decouple anthropogenic from environmental impacts throughout Denmark. Our data show definitive influence of oyster size-age structure through human harvesting during the Mid-Holocene, with older oysters in the Mesolithic (mean: 4.9 y) than the Neolithic (mean: 3.7 y), irrespective of changes in growth rate. Furthermore, we present the metrics for long-term sustainable harvesting of oysters across environmental and socioeconomic transitions, providing demographic targets for current oyster restoration projects and valuable context in mitigating the impact of modern climatic change.

Characterizing the Areal Extent of PFAS Contamination in Fish Species Downgradient of AFFF Source Zones.

Most monitoring programs next to large per- and polyfluoroalkyl substances (PFAS) sources focus on drinking water contamination near source zones. However, less is understood about how these sources affect downgradient hydrological systems and food webs. Here, we report paired PFAS measurements in water, sediment, and aquatic biota along a hydrological gradient away from source zones contaminated by the use of legacy aqueous film-forming foam (AFFF) manufactured using electrochemical fluorination. Clustering analysis indicates that the PFAS composition characteristic of AFFF is detectable in water and fishes >8 km from the source. Concentrations of 38 targeted PFAS and extractable organofluorine (EOF) decreased in fishes downgradient of the AFFF-contaminated source zones. However, PFAS concentrations remained above consumption limits at all locations within the affected watershed. Perfluoroalkyl sulfonamide precursors accounted for approximately half of targeted PFAS in fish tissues, which explain >90% of EOF across all sampling locations. Suspect screening analyses revealed the presence of a polyfluoroketone pharmaceutical in fish species, and a fluorinated agrochemical in water that likely does not accumulate in biological tissues, suggesting the presence of diffuse sources such as septic system and agrochemical inputs throughout the watershed in addition to AFFF contamination. Based on these results, monitoring programs that consider all hydrologically connected regions within watersheds affected by large PFAS sources would help ensure public health protection.

Hazard Characterization of Antibiotic-resistant Aeromonas spp. Isolated from Mussel and Oyster Shellstock Available for Retail Purchase in Canada.

Surveillance and monitoring of foods for the presence of antimicrobial-resistant (AMR) bacteria are required to assess the risks these bacteria pose to human health. Frequently consumed raw or lightly cooked, live bivalve shellfish such as mussels and oysters can be a source of exposure to AMR bacteria. This study sought to determine the prevalence of third-generation cephalosporin (3GC) and carbapenem-resistant bacteria in live mussel and oyster shellstock available for retail purchase through the course of one calendar year. Just over half of the 180 samples (52%) tested positive for the presence of 3GC-resistant bacteria belonging to thirty distinct bacterial species. Speciation of the isolates was carried out using the Bruker MALDI Biotyper. Serratia spp., Aeromonas spp., and Rahnella spp. were the most frequently isolated groups of bacteria. Antibiotic resistance testing confirmed reduced susceptibility for 3GCs and/or carbapenems in 15 of the 29 Aeromonas isolates. Based on AMR patterns, and species identity, a subset of ten Aeromonas strains was chosen for further characterization by whole genome sequence analysis. Genomic analysis revealed the presence of multiple antibiotic resistance and virulence genes. A number of mobile genetic elements were also identified indicating the potential for horizontal gene transfer. Differences in gene detection by the bioinformatic tools and databases used (ResFinder. CARD RGI, PlasmidFinder, and MobSuite) are discussed. This study highlights the strengths and limitations of using genomics tools to perform hazard characterization of diverse foodborne bacterial species.

Fish and shellfish allergy: Presentation and management differences in the UK and US-analysis of 945 patients.

Background: Seafood allergy (SA), including allergy to shellfish (crustacean and mollusks) and fish, is among the 4 most common food allergies causing anaphylaxis, but there are limited data showing SA clinical management in different countries. Objective: We sought to characterize a large cohort of patients with fish and shellfish allergy and to facilitate standardization of future care for this increasingly common allergic disease. Methods: We performed a retrospective, observational, noninterventional study from 945 patients from 2015 to 2019 in 7 hospitals in the United States and the United Kingdom to evaluate SA. A chi-square test was used to detect differences in family history, medical history, and current symptoms between patients in 2 countries. Results: Underdiagnosed anaphylaxis in patients with SA was associated with underuse of epinephrine (adrenaline) autoinjectors in both countries. Oral food challenge was used only when skin or serologic test results were negative. Asthma and allergic rhinitis were more common in the US patients with SA, but eczema was more common in UK patients with SA (P < .001). Respiratory, gastrointestinal, and neurological symptoms were higher in UK patients with SA than in US patients with SA (P < .001). Conclusions: In international multicenter cohorts of patients with fish and shellfish allergy, there are opportunities for improvement in management. Physician identification of anaphylaxis, use of diagnostic oral food challenges, and anaphylaxis treatment with epinephrine are areas with significant knowledge gaps in need of improvement in the United Kingdom and the United States. There is an opportunity for the development of unified, standardized diagnostic protocols for SA with distribution for allergists and trainees.

Natural radioactivity and heavy metal contamination in edible fish, shellfish and mollusks at the Bay of Bengal, Kuakata, Bangladesh.

In this study, gamma activity concentrations, gross alpha and gross beta activity of natural radionuclides, and heavy metal concentrations were measured in eleven edible marine fish, four shellfish, two mollusks, and a common seaweed sample collected from a local sea fish market and sea beach area of the northern part of the Bay of Bengal, Kuakata, Bangladesh. Using HPGe gamma spectrometry, the activity concentrations of 238U, 232Th, and 40K were measured and found to be 19.7 ± 1.5 Bq/kg, 12.2 ± 0.9 Bq/kg, and 188 ± 15 Bq/kg, respectively, with the 232Th concentration surpassing that of 238U. The ZnS scintillation detector was used to assess the gross alpha and gross beta activity. The average gross alpha activity and gross beta activity were found to be 9.4 ± 1.4 Bq/kg and 26 ± 4 Bq/kg, respectively, with the latter attributed to beta emitting radionuclides's abundance. The activity concentrations of 238U, 232Th, and 40K in the analyzed samples varied in the order of Shellfish > Seaweed > Fish > Mollusks, Seaweed > Shellfish > Mollusks > Fish, and Seaweed > Shellfish > Fish > Mollusks. The annual effective dose due to consumption of analyzed seafood was found to be within the world limit of 2400 µSv/y recommended by UNSCEAR. The main contributor to the annual effective dose was 238U. The excess lifetime cancer risk (ELCR) results were below the permissible threshold of 10-3 for radiological risks. Furthermore, average concentrations of Zn and Mn were higher than WHO/FAO recommended values, and carcinogenic Pb, Cd, Cr, and Hg concentrations were below detection limits, according to heavy metal analysis performed by AAS. The average concentration of heavy metals in all of the seafood samples under investigation was in the order of Zn > Fe > Mn. The calculated hazard index (HI), target hazard quotient (THQ), and estimated daily intake (EDI) were compared to the permissible safety limits.

Enzymes from Fishery and Aquaculture Waste: Research Trends in the Era of Artificial Intelligence and Circular Bio-Economy.

In the era of the blue bio-economy, which promotes the sustainable utilization and exploitation of marine resources for economic growth and development, the fisheries and aquaculture industries still face huge sustainability issues. One of the major challenges of these industries is associated with the generation and management of wastes, which pose a serious threat to human health and the environment if not properly treated. In the best-case scenario, fishery and aquaculture waste is processed into low-value commodities such as fishmeal and fish oil. However, this renewable organic biomass contains a number of highly valuable bioproducts, including enzymes, bioactive peptides, as well as functional proteins and polysaccharides. Marine-derived enzymes are known to have unique physical, chemical and catalytic characteristics and are reported to be superior to those from plant and animal origins. Moreover, it has been established that enzymes from marine species possess cold-adapted properties, which makes them interesting from technological, economic and sustainability points of view. Therefore, this review centers around enzymes from fishery and aquaculture waste, with a special focus on proteases, lipases, carbohydrases, chitinases and transglutaminases. Additionally, the use of fishery and aquaculture waste as a substrate for the production of industrially relevant microbial enzymes is discussed. The application of emerging technologies (i.e., artificial intelligence and machine learning) in microbial enzyme production is also presented.

Occurrence, virulence, and AMR profile of Vibrio parahaemolyticus isolated from shellfish growing areas located along the south-west coast of India.

Vibrio parahaemolyticus is a leading cause of human gastroenteritis associated with seafood consumption. The present study aimed to investigate the occurrence and risk assessment of V. parahaemolyticus isolated from live Indian black clams, sediment, and water samples collected from shellfish harvesting areas located along the south-west coast of India. Out of the total 72 samples collected, 55.6% revealed the presence of V. parahaemolyticus; the highest occurrence was observed in shellfish samples. The presence of tdh and trh virulence genes was screened by multiplex PCR. Virulence genes could be detected in 25.8% of the strains; 19.35% of them were trh positive and 3.2% were tdh positive, while 3.2% of strains exhibited the coexistence of both virulence genes. Antimicrobial resistance (AMR) determined by the disk diffusion method revealed that 87% of the strains were multiple drug resistant and exhibited 21 diverse resistance patterns. The overall multiple antibiotic resistance (MAR) index values ranged from 0 to 0.8. To the best of our knowledge, this is the first report to document the presence of pathogenic and multidrug-resistant V. parahaemolyticus in shellfish harvesting areas of the Indian sub-continent. The study reveals possible health hazards associated with consuming shellfish harvested from the study area.

Physiological and transcriptomic response of dinoflagellate Gymnodinium catenatum to nitrate deficiency.

The paralytic shellfish toxin producing dinoflagellate Gymnodinium catenatum is a globally distributed species and often forms massive blooms. However, the physiological and molecular responses of G. catenatum to nitrate starvation have not been thoroughly investigated. Our results showed that multiple forms of N could be utilized by G. catenatum under nitrate-deficient conditions. Nitrate deficiency adversely affected the growth, cellular Chlorophyll a (Chl a) content, and toxin production of G. catenatum. Transcriptomic analysis revealed significant down-regulation of gene expressions involved in the light reaction of photosynthesis, while genes related to fatty acids synthesis and antioxidation were significantly upregulated in the N-depleted cultures. Our results suggested that excess carbon was channeled into lipid synthesis for energy storage, and antioxidant reactions were upregulated to eliminate toxic peroxides caused by nitrate limitation. These findings highlight the adaptative strategy of G. catenatum in low-nitrate environments, which are crucial factors driving its bloom formation.

Droplet Digital PCR for Precise Quantification of Human Norovirus in Shellfish Associated with Gastroenteritis Illness.

Norovirus is the predominant cause of viral gastroenteritis globally with foodborne outbreaks commonly reported. Filter-feeding bivalve molluscan shellfish can become contaminated with norovirus when grown in waters impacted by inadequately treated effluent wastewater, overflows, or other human fecal sources. Contaminated shellfish pose a significant risk to consumers, because combined with a low norovirus infectious dose, oysters and mussels are often eaten raw or lightly cooked resulting in no or minimal virus inactivation, respectively. In addition, shellfish contamination has significant economic impacts on the seafood industry. To improve risk assessments, reverse transcription (RT)-digital droplet PCR (ddPCR) was used to determine the precise norovirus concentrations in 20 shellfish samples, all positive for norovirus genogroup I and/or II (GI or GII) by RT-quantitative PCR (qPCR), and associated with reported norovirus illness in New Zealand. Using RT-ddPCR, total norovirus GI and/or GII concentrations in shellfish ranged between 44 and 4,630 genome copies (GC)/g digestive tissue. Importantly, 40% (8/20) of shellfish samples contained a total norovirus concentration less than 200 GC/g digestive tissue. In parallel, RNase treatment was applied, prior to viral extraction to remove free viral RNA, which subsequently led to average reductions in norovirus GC/g concentration of 37.1% and 19.4% for GI and GII, respectively. These RT-ddPCR data provide valuable evidence for risk assessment of contaminated shellfish and evaluation of safety guidelines and highlight issues associated with setting a safe threshold of norovirus in shellfish.

Bioavailability profiling shows differences in OA, DTX1 and DTX2 toxins that justify their toxicity.

The marine toxins of the Okadaic acid (OA) group are natural compounds produced by dinoflagellates that enters the food chain by accumulating in seafood. They are responsible for Diarrhetic Shellfish Poisoning (DSP) events in humans over the world and therefore are also jointly named as Diarrhetic Shellfish Toxins (DSTs). The main objective of this study was to evaluate symptoms, toxicity, absorption, distribution, and elimination of OA, Dinophysistoxin-1 (DTX1), and Dinophysistoxin-2 (DTX2) at the sublethal dose of 90 µg toxin/kg bw administered through voluntary feeding to mice. The toxin comparison highlighted that OA and DTX1 induced more severe and specific symptoms such as diarrhea. After oral ingestion toxins were distributed through the entire organism being detected in liver, kidney, stomach, small and large intestine. Predominant excretion of the toxins was observed in feces, with OA exhibiting fast elimination, while DTX2 was showing prolonged excretion. The passage and accumulation of toxins in gastrointestinal organs instigated macroscopic damage in the stomach, small and large intestine that could persist up to 120 h. These findings highlight the importance of pharmacokinetic of sublethal doses of DSTs administered by voluntary feeding in their toxicity and their implication for public health.

Two decades of data on the neurotoxic Gymnodinium catenatum dynamics and paralytic shellfish toxins contamination of molluscs in the southwestern Mediterranean: What have we learned?

Harmful algal blooms have been documented in the Moroccan Western Mediterranean region since 1993, primarily associated with the presence of paralytic shellfish toxins (PSTs) produced by the dinoflagellate Gymnodinium catenatum. The proliferation of this neurotoxic species has led to recurring bans on the harvesting of molluscs, resulting in significant socio-economic repercussions and threats to human health. In the present study, we examine the dynamics of G. catenatum and mollusc PST contamination patterns over a 20-year period (2002-2021) in two distinct marine ecosystems: M'diq Bay and the Oued Laou Estuary. For the PST contamination, we considered two commercially important shellfish species: the smooth clam, Callista Chione, and the cockle, Acanthocardia tuberculata. The highest G. catenatum abundances were consistently observed from November to February in both sites. Our data revealed inter-annual variations in G. catenatum abundance, peaking at 91,840 cells.L-1 in November 2011. PST contamination levels in A. tuberculata were significantly higher than those observed in C. chione. Furthermore, we identified a significant correlation (Pearson, P-value <0.05) between PST contamination of smooth clams and the abundance of G. catenatum. The contamination of A. tuberculata by PSTs reached very high levels, with up to 13,500 µg STX di-HCl eq. kg-1 of shellfish meat, exceeding the established safety thresholds by 16-fold. Additionally, there has been an increase in the prevalence and incidence of PSTs over the years. Notably, we observed a substantial increase in G. catenatum blooms and PST events in the Western Mediterranean during the last decade (2010-2021). The examined data suggest that rainfall could play a pivotal role in G. catenatum bloom dynamics by enriching marine waters with nutrients. The statistical model selection approaches indicated that nutrient concentrations (i.e., nitrate and phosphorus) were the most significant parameters for G. catenatum blooms in the studied area.

Longitudinal Study of Seafood and Fish Oil Supplement Intake and Risk of Persistent Tinnitus.

BACKGROUND: Persistent tinnitus is common, disabling, and difficult to treat. Diet has been implicated in tinnitus etiology, but studies are inconsistent and longitudinal data are scarce. Seafood intake is associated with lower risk of hearing loss, but the longitudinal association with tinnitus is unknown. OBJECTIVE: We examined the independent associations of seafood intake, fish oil supplement use, and risk of developing persistent tinnitus. METHODS: This prospective cohort study followed 73,482 females in the Nurses' Health Study II from 1991 to 2021. Diet was assessed using a validated food frequency questionnaire every 4 years. Multivariable-adjusted Cox proportional hazards regression was used to evaluate independent associations between total seafood intake, specific types of fish, shellfish, fish oil supplements, and risk of persistent tinnitus (defined as tinnitus experienced daily). RESULTS: After 1,998,421 person-years of follow-up, 9,362 cases of incident persistent tinnitus were reported. Seafood intake was independently associated with lower risk of developing persistent tinnitus. Compared with participants who never or rarely consumed seafood, the multivariable-adjusted hazard ratios (MVHR,95% CI) for tinnitus were 0.87 (0.78, 0.95) among participants who consumed 1 serving/week, 0.77 (0.68, 0.86) for 2-4 servings/week, and 0.79 (0.64, 0.96) for 5+/servings/week (p-trend<0.0001). Examined individually, higher intakes of tuna fish, light-meat fish and shellfish were associated with lower risk. Compared with participants who never or rarely consumed the specific type, the MVHRs for consumption of 1+ servings/week were 0.84 (0.78, 0.90)(p-trend <0.0001) for tuna fish, 0.91 (0.83, 0.99)(p-trend=0.04) for light-meat fish, and 0.82 (0.72, 0.93)(p-trend<0.0001) for shellfish. Higher risk for dark-meat fish intake was suggested (MVHR: 1.09 (0.99,1.21)(p-trend=0.04). Fish oil supplement use (yes/no) was associated with higher risk (MVHR: 1.12 (1.06,1.19)). CONCLUSION: Regular consumption of tuna fish, light-meat fish or shellfish is associated with lower risk of developing persistent tinnitus in females. Fish oil supplement use is associated with higher risk.