Spatiotemporal variation of paralytic shellfish toxins in the sea area adjacent to the Changjiang River estuary

The Changjiang (Yangtze River) River estuary (CRE) and its adjacent coastal waters is a notable region for nutrient pollution, which results in severe problems of coastal eutrophication and harmful algal blooms (HABs). The occurrence of HABs, particularly those of dinoflagellate Alexandrium spp. capable of producing paralytic shellfish toxins (PSTs), has an increasing risk of contaminating seafood and poisoning human-beings. The investigation of PSTs, however, is often hampered by the relatively low abundance of Alexandrium spp. present in seawater. In this study, a monitoring strategy of PSTs using net-concentrated phytoplankton from a large volume of seawater was employed to examine spatiotemporal variations of PSTs in the CRE and its adjacent waters every month from February to September in 2015. Toxins in concentrated phytoplankton samples were analyzed using high-performance liquid chromatography coupled with a fluorescence detector (HPLC-FLD). The results showed that PSTs could be detected in phytoplankton samples during the sampling stage in the CRE and its adjacent waters. Toxin content increased gradually from February to May, reached the peak in June, and then decreased rapidly from July to September. The maximum value of PST content was 215 nmol m^-3 in June. Low-potency toxins N-sulfocarbamoyl toxins 1/2 (C1/2) were the most dominant components of PST in phytoplankton samples from February to June in 2015, while high-potency gonyautoxin 4 (GTX4) became the dominant component from July to September. Toxins were mainly detected from three regions, the sea area north to the CRE, the sea area east to the CRE, and sea area near Zhoushan Island south to the CRE. Based on the results of this study, it can be inferred that the three regions around the CRE in May and June is of high risk for PST contamination and seafood poisoning.

Predicting fish kills and toxic blooms in an intensive mariculture site in the Philippines using a machine learning model

Harmful algal blooms (HABs) that produce toxins and those that lead to fish kills are global problems that appear to be increasing in frequency and expanding in area. One way to help mitigate their impacts on people's health and livelihoods is to develop early-warning systems. Models to predict and manage HABs typically make use of complex multi-model structures incorporating satellite imagery and frequent monitoring data with different levels of detail into hydrodynamic models. These relatively more sophisticated methods are not necessarily applicable in countries like the Philippines. Empirical statistical models can be simpler alternatives that have also been successful for HAB forecasting of toxic blooms. Here, we present the use of the random forest, a machine learning algorithm, to develop an early-warning system for the prediction of two different types of HABs: fish kill and toxic bloom occurrences in Bolinao-Anda, Philippines, using data that can be obtained from in situ sensors. This site features intensive and extensive mariculture activities, as well as a long history of HABs. Data on temperature, salinity, dissolved oxygen, pH and chlorophyll from 2015 to 2017 were analyzed together with shellfish ban and fish kill occurrences. The random forest algorithm performed well: the fish kill and toxic bloom models were 96.1% and 97.8% accurate in predicting fish kill and shellfish ban occurrences, respectively. For both models, the most important predictive variable was a decrease in dissolved oxygen. Fish kills were more likely during higher salinity and temperature levels, whereas the toxic blooms occurred more at relatively lower salinity and higher chlorophyll conditions. This demonstrates a step towards integrating information from data that can be obtained through real-time sensors into a an early-warning system for two different types of HABs. Further testing of these models through times and different areas are recommended.

Rethinking the Minamata Tragedy: What Mercury Species Was Really Responsible?

Industrial release of mercury into the local Minamata environment with consequent poisoning of local communities through contaminated fish and shellfish consumption is considered the classic case of environmental mercury poisoning. However, the mercury species in the factory effluent has proved controversial, originally suggested as inorganic, and more recently as methylmercury species. We used newly available methods to re-examine the cerebellum of historic Cat 717, which was fed factory effluent mixed with food to confirm the source. Synchrotron high-energy-resolution fluorescence detection-X-ray absorption spectroscopy revealed sulfur-bound organometallic mercury with a minor β-HgS phase. Density functional theory indicated energetic preference for α-mercuri-acetaldehyde as a waste product of aldehyde production. The consequences of this alternative species in the "classic" mercury poisoning should be re-evaluated.

Heat shock protein 70 levels and post-harvest survival of eastern oysters following sublethal heat shock in the laboratory or conditioning in the field

A major problem of storing and shipping eastern oysters (Crassostrea virginica) from the Northern Gulf of Mexico in summer and early fall is their elevated mortality. A study was therefore conducted to determine whether heat shocking the oysters or conditioning them to aerial exposure prior to harvest could reduce their mortality during cold storage. Increasing the levels of stress proteins in bivalves has been shown to reduce their mortality when exposed to additional stressors. In this study, the levels of heat shock protein 70 (HSP70) proteins and cumulative mortality during cold storage, out of water, of market-sized oysters were measured, in summer, following (1) sublethal heat shocks (41 °C, 1 h) in the laboratory or (2) 3 weeks to 6 weeks of daily exposures to air (0 h, ~ 10 h, or ~ 18 h) in the field. In total, four heat shock and two aerial exposure studies were done. Consistently, heat shocks or 6 weeks of daily aerial exposures increased HSP70 levels in oysters but did not reduce their mortality during cold storage. Three weeks of daily aerial exposure did not increase HSP70 levels and only marginally reduced mortality; a significant reduction in cumulative mortality occurred in one of the aerial exposure studies after 7 days of cold storage (0 h [26%], ~ 18 h [8%]). In conclusion, upregulation of HSP70 proteins or aerial exposure during grow-out was not an effective tool in reducing the mortality of oysters harvested in summer and held in cold storage.

Phylogenetic relationships and genetic divergence of paralytic shellfish toxin- and cylindrospermopsin- producing Cylindrospermopsis and raphidiopsis

Cylindrospermopsis and Raphidiopsis (C/R group) are closely related species responsible for cyanobacterial blooms worldwide. Paralytic shellfish toxins (PSTs) and cylindrospermopsins (CYNs) have been identified in different C/R group strains. However, the evolutionary relationship between PST- and CYN-producing strains has not been systematically evaluated. In this study, C/R group strains and their toxin biosynthesis genes were evaluated by phylogenetic analysis and sequence comparison. None of the tested strains are able to produce PSTs and CYNs simultaneously. The C/R group strains were clustered into five clades, including two non-toxic, two CYN-producing and one PST-producing clades. A high degree of similarity was observed for rpoC1 (> 96%) and ITS-L (> 97%) sequences within each clade with the exception of the ITS-L (87% to 100%) region in CYN-producing R. curvata, which has been shown to contain variable sequence insertions. Genomic analysis revealed that sxtY and sxtZ could be found in both toxic and non-toxic strains. The transposase gene IS4 was only observed in strains from the PST-producing clade. The sxt and cyr gene clusters share five gene families with similar functions. The amino acid sequences of the adenylyl-sulfate kinase genes, sxtO and cyrN, are more similar (45% to 81%) than other pairs of genes (8.0% to 40%). SxtO and CyrN proteins from C/R group strains forms an independent clade on the phylogenetic tree with a high degree of sequence similarity (78% to 100%). In conclusion, PST- and CYN- producing C/R group species can be classified into different clades based on their phylogenetic profile. The sxtO and cyrN genes have probably diverged from a single ancestral adenylyl-sulfate kinase gene, and may be specifically used for toxin biosynthesis in C/R group species.

Accumulation and esterification of diarrhetic shellfish toxins from the aqueous phase in laboratory-exposed mussels

In recent years, marine bivalves cultured in the natural environment have been confirmed to accumulate diarrhetic shellfish toxins (DSTs) from the aqueous phase. To investigate the effects of varying seston concentrations on DST accumulation, mussels (Mytilus galloprovincialis) were exposed to comparable concentrations of okadaic acid (OA) and dinophysistoxin-1 (DTX1) in 0.45-μm filtered seawater spiked with varying concentrations of ambient suspended particles at 0, 10, 30, 60, 90, and 120 mg L^-1, for 96 h. Effects of seston additions on the mussels' feeding on nontoxic microalgae, Isochrysis galbana, the stability of dissolved toxins and the anatomical compartmentalization of toxins were also assessed. Results showed that mussels more readily accumulated OA than DTX1 from the aqueous phase. Three potential mechanisms of the effects of seston on toxin accumulation were identified. First, seston at low concentrations (10 mg L^-1) adsorbed toxins and thus promoted toxin accumulation. Second, seston enhanced the degradation of aqueous OA and DTX1, and possibly reduced the adsorption by digestive gland (DG) cells through simple diffusion due to competitive adsorption. Third, the clearance rate of mussels was significantly reduced at high seston concentrations (120 mg L^-1). The esterification of DSTs was maximized in DG tissue, although a high percentage (52%) of DSTs was distributed in non-visceral tissues of mussels exposed to aqueous toxins. This study suggests that the risk of benthic DST-producing microalgae to marine cultured shellfish should be taken into consideration, even in the absence of a bloom of toxic microalgae in the water column.

Assessment of heavy metals in water, sediment and shellfish organisms in typical areas of the Yangtze River Estuary, China

Identifying the transformations of heavy metal in different media is a scientific issue, and geographical detector is applied to evaluate the spatiotemporal stratified heterogeneity mechanisms for heavy metals in the Yangtze River Estuary. Heavy metal concentrations in water and sediment were consistent with lognormal distributions. Their concentrations were organized into four classes. Class 1 included concentrations that were less than or equal to 25%, Class 2 included those between 25%-50%, Class 3 concentrations were between 50%-75% and Class 4 were >75%, which were based on their lognormal distributions. In water and sediment, the mean heavy metal concentrations yearly decreased from 2012 to 2016. The Chongming area was significantly lower than those found in the other areas, which is the least affected area by anthropogenic activities. The explanatory power of sediment to spatiotemporal stratified heterogeneity of heavy metals in shellfish organisms was much greater than that of water.

Fatty acid ester metabolites of gymnodimine in shellfish collected from China and in mussels (Mytilus galloprovincialis) exposed to Karenia selliformis

Marine shellfish exposed to the microalgae Karenia selliformis can accumulate gymnodimines (GYM). Shellfish samples collected from Beihai City in Guangxi Autonomous Region, and Ningde City in Fujian Province, in the South China Sea, as well as mussels Mytilus galloprovincialis fed on K. selliformis under laboratory conditions were analyzed. Gymnodimines and various fatty acid ester metabolites were detected in the clam Antigona lamellaris and pen shell Atrina pectinata, while no esters were found in the oyster Crassostrea sp. and the gastropod Batillaria zonalis despite positive detection of free GYM in both species. When present, the predominant acyl esters observed were 18:0-GYM-A and 20:1-GYM-A. Under laboratory conditions GYM-A was accumulated and metabolized to fatty acid esters in mussels exposed to K. selliformis, with 16:0-GYM-A and 20:1-GYM-A as the major variants. A novel compound with the same accurate mass as GYM-A and its 16:0 fatty acid ester were observed in the experimental mussels but was not present in the microalgal strain to which mussels were exposed. No significant differences of reactive oxygen species (ROS) levels and antioxidant enzymes were found between mussels fed on K. selliformis or GYM-free microalgae Isochrysis galbana. This suggests the accumulation of GYM and its metabolites does not significantly impact the physiological status of mussels. While it is currently not proven that GYM affects human health, risk assessments should consider the presence of GYM esters in naturally contaminated shellfish as part of exposure analysis.

Bioaccumulation and human health risk of shellfish contamination to heavy metals and As in most rapid urbanized Shenzhen, China

Despite the benefits of shellfish consumption, the bioaccumulation of heavy metals in shellfish can endanger consumer's health. The consumption of seafood in Shenzhen (a fast-developing metropolis in China) has received more and more attention. Arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), and lead (Pb) in ten common shellfish species and associated health risks were analyzed for Shenzhen's consumers by evaluating estimated weekly intake (EWI), non-carcinogenic and carcinogenic health risks to children, adolescents, and adults. In this study, 50 shellfish samples were collected in total. The results showed that the levels of inorganic arsenic (iAs) in Babylonia areolata exceeded the maximum permissible limit set by the food safety guidelines (0.5 mg/kg), while other elements were below the limit in the present guidelines (Ministry of Health of the People's Republic of China, GB 2762-2012). EWI values of children, adolescents, and adults were all lower than provisional tolerable weekly intakes (PTWIs) of all shellfish species. The analysis of total target hazard quotients (TTHQ) showed that the ingested B. areolata in children, adolescents, and adults were all at non-carcinogenic risks; the consumption of Argopecten irradians and Chlamys farreri would pose non-carcinogenic risks for children only. In all age groups, the consumption of A. irradians, B. areolata, C. farreri, and Crassostrea ariakensis would lead to lifetime cancer risk due to Cd bioaccumulation, with toxicity of Pb and iAs to be acceptable and negligible.

Variability of dinoflagellates and their associated toxins in relation with environmental drivers in Ambon Bay, eastern Indonesia

The aim of the present work was to unravel which environmental drivers govern the dynamics of toxic dinoflagellate abundance as well as their associated paralytic shellfish toxins (PSTs), diarrhetic shellfish toxins (DSTs) and pectenotoxin-2 (PTX2) in Ambon Bay, Eastern Indonesia. Weather, biological and physicochemical parameters were investigated weekly over a 7-month period. Both PSTs and PTX2 were detected at low levels, yet they persisted throughout the research. Meanwhile, DSTs were absent. A strong correlation was found between total particulate PST and Gymnodinium catenatum cell abundance, implying that this species was the main producer of this toxin. PTX2 was positively correlated with Dinophysis miles cell abundance. Vertical mixing, tidal elevation and irradiance attenuation were the main environmental factors that regulated both toxins and cell abundances, while nutrients showed only weak correlations. The present study indicates that dinoflagellate toxins form a potential environmental, economic and health risk in this Eastern Indonesian bay.

Spatial variability in Polonium-210 and Lead-210 activity concentration in New Zealand shellfish and dose assessment

The activity concentrations of Polonium-210 (²¹⁰Po) and Lead-210 (²¹⁰Pb) were determined in shellfish (Perna canaliculus and Paphies subtriangulata) sampled bimonthly from March 2018 to February 2019 from 14 sites around New Zealand. Activity concentrations of ²¹⁰Po ranged from 4.7 ± 1.1 to 324 ± 17 Bq. kg^-1 with a mean value of 57 ± 72 Bq. kg^-1 (wet weight). The activity concentrations of ²¹⁰Pb were lower than those for ²¹⁰Po (0.1 ± 0.4 and 1.9 ± 0.4 Bq. kg^-1, with a mean value of 0.7 ± 0.4 Bq. kg^-1, wet weight). The calculated ²¹⁰Po/²¹⁰Pb activity concentration ratios were higher than unity in all samples indicating that radionuclides are not in equilibrium in shellfish and most of the ²¹⁰Po was unsupported by its grandparent ²¹⁰Pb. No significant difference was noted in ²¹⁰Po activity concentration between different seasons, species or shellfish condition index. Significant spatial variability in ²¹⁰Po activity concentration was observed with elevated ²¹⁰Po activity concentration in two sampling sites: Ninety Mile Beach (mean 257 ± 47 Bq. kg^-1) and Maunganui Bluff (mean 127 ± 22 Bq. kg^-1). Elevated ²¹⁰Po is hypothesised to be related to an increase of ²¹⁰Po accumulation through diet. Individuals who consume large quantities of shellfish (10 g per day or more) from areas affected by elevated ²¹⁰Po activity concentration may be exposed to an annual committed effective dose from ²¹⁰Po in shellfish in excess of 1 mSv.

Idiopathic anaphylaxis: What you do not know may hurt you

Idiopathic anaphylaxis (IA), like immunologic and nonimmunologic anaphylaxis, is a life-threatening, sometimes fatal allergic disease. Although the priority is immediate recognition and initiation of treatment, long-term care planning is important to help reduce anxiety and promote healthy growth and development. Learning to recognize, manage, and stabilize the child is an essential part of improving the family dynamics. Despite advancements in the management of anaphylaxis, research has shown a need for continued patient education and training to improve timely recognition and treatment. This article focuses on elucidating the clinical presentation, theories of pathogenesis, and diagnosis, treatment, and management of IA.

Microplastics detected in haemolymph of the Sydney rock oyster Saccostrea glomerata

Plastic waste is ubiquitous in marine environments. Despite the sheer volume of plastic waste, it remains relatively unknown how marine invertebrates will interact with microplastics (plastic <1 mm). Microplastics (<2 μm) were ingested by the economically and ecologically significant Sydney rock oyster Saccostrea glomerata and translocated to the haemolymph, perhaps via phagocytosis. The presence of microplastics in the haemolymph indicates that filter feeding S. glomerata can ingest and accumulate microplastics which are prevalent in the environment. This research shows microplastics can enter marine molluscs and highlights the need to monitor microplastics in the marine environment and aquaculture to safeguard the seafood industry.

Effects of small-scale turbulence on two species of Dinophysis

Dinoflagellate species of Dinophysis, in particular D. acuminata and D. acuta, produce lipophilic toxins that pose a threat to human health when concentrated in shellfish and jeopardize shellfish exploitations in western Europe. In northwestern Iberia, D. acuminata has a long growing season, from spring to early autumn, and populations develop as soon as shallow stratification forms when the upwelling season begins. In contrast, D. acuta blooms in late summer, when the depth of the pycnocline is maximal and upwelling pulses are moderate. In situ observations on the hydrodynamic regimes during the two windows of opportunity for Dinophysis species led us to hypothesize that D. acuta should be more sensitive to turbulence than D. acuminata. To test this hypothesis, we studied the response of D. acuminata and D. acuta to three realistic turbulence levels low (LT), ε ≈ 10^-6 m² s^-3; medium (MT), ε ≈ 10^-5  m² s^-3 and high (HT), ε ≈ 10^-4 m² s^-3generated by Turbogen, a highly reproducible, computer-controlled system. Cells of both species exposed to LT and MT grew at rates similar to the controls. Marked differences were found in the response to HT: D. acuminata grew slowly after an initial lag phase, whereas D. acuta cell numbers declined. Results from this study support the hypothesis that turbulence may play a role in shaping the spatio-temporal distribution of individual species of Dinophysis. We also hypothesize that, in addition to cell disturbance affecting division, sustained high shear generated by microturbulence may cause a decline in Dinophysis numbers due to decreased densities of ciliate prey.

Effect of the Algicide Thiazolidinedione 49 on Immune Responses of Bay Scallop Argopecten Irradians

The thiazolidinedione 49 (TD₄₉) is an effective algaecide against harmful algae; however, its potential effects on the immune function of the edible bay scallop are unclear. Therefore, the present work studied the effects of TD₄₉ on the immune response in bay scallop by evaluating activities of acid phosphatase (ACP), alkaline phosphatase (ALP), and superoxide dismutase (SOD), as well as nitric oxide (NO) levels, total protein content, and expression of immune genes (CTL-6, PGRP, PrxV, MT, and Cu/Zn-SOD) at 3–48 h post-exposure (hpe) to TD₄₉. The activities of ACP and ALP significantly increased in TD₄₉-treated groups at 3–24 hpe, whereas NO levels decreased significantly in 0.58 and 0.68 μM of TD₄₉ at 6–24 hpe, after which the level was similar to that in the untreated control. Moreover, SOD activity significantly increased in all three concentration groups at 3–6 hpe, while it decreased at 12 hpe in the 0.68 μM TD₄₉ treatment group. Notably, total protein content increased with TD₄₉ treatment at each time interval. The results revealed that variable effects on the expression of immune-related genes were observed after treatment with TD₄₉. The findings demonstrate that exposure of scallops to TD₄₉ changes immune responses and expression of immune-related genes. We hypothesize that TD₄₉ may disrupt immune system in bay scallop. The current investigation highlights the potential negative effects of using TD₄₉ as an algaecide on marine economic bivalves to control harmful algal blooms in marine environments.

Environmental drivers of paralytic shellfish toxin producing Alexandrium catenella blooms in a fjord system of northern Southeast Alaska

Paralytic shellfish poisoning (PSP) is a persistent problem that threatens human health and the availability of shellfish resources in Alaska. Regular outbreaks of marine dinoflagellates in the genus Alexandrium produce paralytic shellfish toxins (PSTs) that make shellfish consumption unsafe, and impose economic hardships on Alaska's shellfish industry. Phytoplankton and environmental monitoring spanning 2008-2016, and a pilot benthic cyst survey in 2016, were focused in the Juneau region of Southeast Alaska to investigate Alexandrium catenella distributions and conditions favorable to bloom development. Overwintering Alexandrium cysts were found in near-shore sediments throughout the study region. Alexandrium catenella cells were present in the water column across a range of sea surface temperatures (7-15 °C) and surface salinities (S = 4-30); however, an optimal temperature/salinity window (10-13 °C, 18-23) supported highest cell concentrations. Measurable levels of PSTs were associated with lower concentrations (100 cells L^-1) of A. catenella, indicating high cell densities may not be required for shellfish toxicity to occur. Several interacting local factors were identified to support A. catenella blooms: 1) sea surface temperatures ≥7 °C; 2) increasing air temperature; 3) low to moderate freshwater discharge; and 4) several consecutive days of dry and calm weather. In combination, these bloom favorable conditions coincide with toxic bloom events during May and June in northern Southeast Alaska. These findings highlight how integrated environmental and phytoplankton monitoring can be used to enhance early warning capacity of toxic bloom events, providing more informed guidance to shellfish harvesters and resource managers in Alaska.

Trends in Dinophysis abundance and diarrhetic shellfish toxin levels in California mussels (Mytilus californianus) from Monterey Bay, California

Diarrhetic shellfish toxins (DSTs) are produced by the marine dinoflagellate, Dinophysis, as well as select species of benthic Prorocentrum. The DSTs can bioaccumulate in shellfish and cause gastrointestinal illness when humans consume high levels of this toxin. Although not routinely monitored throughout the U.S., recent studies in Washington, Texas, and New York suggest DSTs may be widespread throughout U.S. coastal waters. This study describes a four-year time series (2013-2016) of Dinophysis concentration and DST level in California mussels (Mytilus californianus) from Santa Cruz Municipal Wharf (SCMW) in Monterey Bay, California. Results show a maximum Dinophysis concentration of 9404 cells/L during this study and suggest Dinophysis persists as a member of the background phytoplankton community throughout the year. In California mussels, DSTs were found at persistent low levels throughout the course of this study, and exceeded the FDA guidance level of 160 ng/g 19 out of 192 weeks sampled. Concentrations of Dinophysis alone are a positive but weak predictor of DST level in California mussels, and basic environmental variables (temperature, salinity, and nutrients) do not sufficiently explain variation in Dinophysis concentration at SCMW. This study demonstrates that Dinophysis in Monterey Bay are producing DSTs that accumulate in local shellfish throughout the year, occasionally reaching levels of concern.

Histopathological lesions, pathogens and parasites as health indicators of an edible clam (Protothaca thaca) inhabiting a bay exposed to anthropogenic activities in Northern Chile

San Jorge Bay (23° S) is characterised by a permanent coastal upwelling front and a thermal front that influence water circulation into the bay. This bay constantly receives effluents from different mining activities. Several studies have demonstrated different levels of heavy metals in waters and sediments within the bay. The clam Protothaca thaca is a bivalve with sedentary habits, which is distributed along the Peruvian and Chilean coasts and is exploited commercially. During 2010, clams were collected inside the bay: north (La Chimba), centre (Paraíso) and south (Llacolén), as well as from a site outside the bay (Bolsico). Haematological parameters, condition factor index, lesions, parasites and pathogens and heavy metal concentrations in clam tissues were determined. The health indicators of clams inhabiting the bay varied between sites. Clams inside the bay showed higher prevalence and intensity of parasites and lesions than those clams inhabiting the site outside the bay, which could be indicating the presence of some environmental stressor (e.g. heavy metals). This study is the first to evaluate the health status of organisms from San Jorge Bay, and our results support the hypothesis that clams P. thaca can be used to evaluate environmental quality.

Tool use by the graphic tuskfish Choerodon graphicus

We describe how the graphic tuskfish Choerodon graphicus in New Caledonia uses rocks and coral heads as anvils to break open bivalves to obtain food. Video revealed that C. graphicus can make as many as 28 strikes on two anvils over 6 min in a single event. This example of tool use in fishes extends the behaviour taxonomically and geographically and supports the hypothesis that tool use may be widespread in wrasses, particularly those in the Choerodon genus.

Saving the vaquita one bite at a time: The missing role of the shrimp consumer in vaquita conservation

The vaquita (Phocoena sinus) is the world's smallest cetacean and most endangered marine mammal. The species is under threat from illegal fishing activities that take place in the upper Gulf of California (UGC). Artisanal use of gillnets to catch shrimp and poach the endangered totoaba are the primary drivers of vaquita population declines due to bycatch. About 80% of shrimp caught in the UGC is sold to the United States, meaning Americans who consume shrimp may have a direct connection to the plight of the critically endangered vaquita. However, this issue as part of the human dimensions of vaquita conservation has been largely unstudied. Additionally, the majority of Americans are unfamiliar with the vaquita which hinders conservation efforts. This article calls for further research into the human dimensions of vaquita conservation, increased collaboration with fishing communities in the UGC, and connecting seafood sellers and consumers with the vaquita crisis.

Biofouling in marine aquaculture: a review of recent research and developments

Biofouling in marine aquaculture is one of the main barriers to efficient and sustainable production. Owing to the growth of aquaculture globally, it is pertinent to update previous reviews to inform management and guide future research. Here, the authors highlight recent research and developments on the impacts, prevention and control of biofouling in shellfish, finfish and seaweed aquaculture, and the significant gaps that still exist in aquaculturalists' capacity to manage it. Antifouling methods are being explored and developed; these are centred on harnessing naturally occurring antifouling properties, culturing fouling-resistant genotypes, and improving farming strategies by adopting more sensitive and informative monitoring and modelling capabilities together with novel cleaning equipment. While no simple, quick-fix solutions to biofouling management in existing aquaculture industry situations have been developed, the expectation is that effective methods are likely to evolve as aquaculture develops into emerging culture scenarios, which will undoubtedly influence the path for future solutions.

Variability of Amnesic Shellfish Toxin and Pseudo-nitzschia occurrence in bivalve molluscs and water samples-Analysis of ten years of the official control monitoring programme

As the official control laboratory for marine biotoxins within Great Britain, the Centre for Environment, Fisheries and Aquaculture Science, in conjunction with the Scottish Association for Marine Science, has amassed a decade's worth of data regarding the prevalence of the toxins associated with Amnesic Shellfish Poisoning within British waters. This monitoring involves quantitative HPLC-UV analysis of shellfish domoic acid concentration, the causative toxin for Amnesic Shellfish Poisoning, and water monitoring for Pseudo-nitzschia spp., the phytoplankton genus that produces domoic acid. The data obtained since 2008 indicate that whilst the occurrence of domoic acid in shellfish was generally below the maximum permitted limit of 20 mg/kg, there were a number of toxic episodes that breached this limit. The data showed an increase in the frequency of both domoic acid occurrence and toxic events, although there was considerable annual variability in intensity and geographical location of toxic episodes. A particularly notable increase in domoic acid occurrence in England was observed during 2014. Comparison of Scottish toxin data and Pseudo-nitzschia cell densities during this ten-year period revealed a complex relationship between the two measurements. Whilst the majority of events were associated with blooms, absolute cell densities of Pseudo-nitzschia did not correlate with domoic acid concentrations in shellfish tissue. This is believed to be partly due to the presence of a number of different Pseudo-nitzschia species in the water that can exhibit variable toxin production. These data highlight the requirement for tissue monitoring as part of an effective monitoring programme to protect the consumer, as well as the benefit of more detailed taxonomic discrimination of the Pseudo-nitzschia genus to allow greater accuracy in the prediction of shellfish toxicity.

Urinary bisphenol A (BPA) concentrations and exposure predictors among pregnant women in the Laizhou Wan Birth Cohort (LWBC), China

Although BPA use is widespread and often detectable in humans, little is known about its exposure levels and potential exposure predictors in pregnant women in China. We investigated the BPA exposure levels in pregnant women and its health implications and potential exposure predictors. Urinary BPA levels were measured for 506 pregnant women in northern China. Hazard quotients (HQs) based on estimated daily intakes (EDIs) were conducted. Sociodemographic characteristics and food consumption during pregnancy were collected and seasons of sample collection were recorded. The detection rate of urinary BPA was 86.6% and the median concentrations were 0.48 μg/L (1.05 μg/g creatinine). The EDI (median = 0.008 μg/kg bw/day) was much lower than the recommended tolerable daily doses and the HQ (median = 0.002) much lower than 1. The urine collected in summer had significantly higher BPA levels than that collected in other seasons (β = 0.225; 95% CI - 0.008, 0.458; p = 0.03). Women "always consuming shellfish" had significantly higher BPA levels than those "seldom consuming shellfish" (β = 0.341; 95% CI 0.022, 0.66; p = 0.04). The study found a wide exposure to BPA among pregnant women in this region, which might be associated with seasonal variation and shellfish consumption. Although the HQs suggested no obvious risk, further attention to the comprehensive exposure and potential determinants should be paid in view of its endocrine-disrupting potential.

Determination of the geographical origin of marine mussels (Mytilus spp.) using 143Nd/144Nd ratios

Geographical traceability of marine bivalves is critical to guarantee their quality and safeguard the interest of both consumers and producers. The neodymium isotopic ratio (¹⁴³Nd/¹⁴⁴Nd) of the coastal water mainly reflects the geology of its neighboring watershed, displaying the distinct and systematic variability at high level of geographical detail and thereby shedding light on its potential as a geochemical tracer. For the first time, the present study investigated the utility and robustness of ¹⁴³Nd/¹⁴⁴Nd archived in mytilid mussel shells for geographical traceability purposes. The reproducibility of ¹⁴³Nd/¹⁴⁴Nd ratios maintained in mussels shells from the same cohort demonstrates that the Nd isotopic ratio meets the major requirement for an ideal geochemical tracer, i.e., the biologically induced variation should be rather minimal. The distribution and variability of mussel shell ¹⁴³Nd/¹⁴⁴Nd patterns were subsequently mapped along the Japanese and Chinese coastal waters. Neodymium isotopes of mussel shells record ¹⁴³Nd/¹⁴⁴Nd variations among local regions and between the two countries, which are rather compatible with the ages and lithology of the continental bedrocks. These findings highlight the great potential of ¹⁴³Nd/¹⁴⁴Nd for tracing the geographical origin of marine bivalves.

Discovery of a Potential Human Serum Biomarker for Chronic Seafood Toxin Exposure Using an SPR Biosensor

Domoic acid (DA)-producing harmful algal blooms (HABs) have been present at unprecedented geographic extent and duration in recent years causing an increase in contamination of seafood by this common environmental neurotoxin. The toxin is responsible for the neurotoxic illness, amnesic shellfish poisoning (ASP), that is characterized by gastro-intestinal distress, seizures, memory loss, and death. Established seafood safety regulatory limits of 20 μg DA/g shellfish have been relatively successful at protecting human seafood consumers from short-term high-level exposures and episodes of acute ASP. Significant concerns, however, remain regarding the potential impact of repetitive low-level or chronic DA exposure for which there are no protections. Here, we report the novel discovery of a DA-specific antibody in the serum of chronically-exposed tribal shellfish harvesters from a region where DA is commonly detected at low levels in razor clams year-round. The toxin was also detected in tribal shellfish consumers’ urine samples confirming systemic DA exposure via consumption of legally-harvested razor clams. The presence of a DA-specific antibody in the serum of human shellfish consumers confirms long-term chronic DA exposure and may be useful as a diagnostic biomarker in a clinical setting. Adverse effects of chronic low-level DA exposure have been previously documented in laboratory animal studies and tribal razor clam consumers, underscoring the potential clinical impact of such a diagnostic biomarker for protecting human health. The discovery of this type of antibody response to chronic DA exposure has broader implications for other environmental neurotoxins of concern.

Evaluation of pepper mild mottle virus as an indicator of human faecal pollution in shellfish and growing waters

Bivalve molluscan shellfish grown in areas impacted by human faecal pollution are at risk of being contaminated with multiple enteric viruses. To minimise the public health risks associated with shellfish consumption, determining the presence of faecal contamination in shellfish and their growing waters is crucial. In this study, we evaluated the use of pepper mild mottle virus (PMMoV) as an indicator of human faecal contamination in oysters, mussels, cockles and shellfish growing waters in New Zealand. Using reverse transcription quantitative polymerase chain reaction (RT-qPCR) the presence, and where applicable, the concentration of PMMoV was determined in faeces from 11 different animal species, influent (untreated) wastewater, shellfish and shellfish growing waters. Non-human faecal samples (from seagull, Canada goose, black swan and dog) were RT-qPCR positive for PMMoV. The faecal source specificity of PMMoV was 0.83 (maximum value of 1) when 'detected but not quantifiable' (DNQ) values were used. However, when 'lower limit of quantification' (LLOQ) values were used, the specificity increased to 0.92. The PMMoV concentration in influent wastewater (n = 10) ranged from 6.3 to 7.7 log₁₀ genome copies (GC)/L with a mean (±standard deviation) of 7.1 ± 0.5 log₁₀ GC/L. The overall occurrence of PMMoV in shellfish and shellfish growing waters from four different areas was 46/51 (90%) and 29/52 (56%), respectively. Of the cockles collected from an area known to be impacted by effluent wastewater, 14/14 (100%) contained PMMoV concentrations above the LLOQ. In contrast, only 13/37 (35%) shellfish and 6/52 (11.5%) growing water samples collected from three areas with low anthropogenic impact contained PMMoV concentrations above the LLOQ. The high concentration of PMMoV in influent wastewater indicates that PMMoV may be a promising indicator of human faecal contamination. The presence of PMMoV in shellfish and growing waters with a low anthropogenic impact may be of avian origin, and this needs to be considered if using PMMoV for monitoring shellfish and shellfish growing water quality in New Zealand.

Effects of hypoxia on survival, behavior, metabolism and cellular damage of Manila clam (Ruditapes philippinarum)

The Manila clam Ruditapes philippinarum has become a common and dominant macrobenthic species in coastal areas of the northwestern Pacific and temperate waters of Europe; it is also a major cultured shellfish, with annual worldwide production exceeding 3.3 million tonnes. This species faces greater risk of exposure to hypoxia as eutrophication worsens throughout its coastal habitats; however, its tolerance to hypoxia remains unclear, and the toxicological indicators including LC₅₀ and LT₅₀ have not yet been assessed. Previous studies on the effects of hypoxia on marine benthos have focused largely on functional responses, such as metabolism and gene expression, leaving potential structural damage to the mitochondria or the cells unknown. In this study we assessed the effects of hypoxia on Manila clam in terms of survival, behavior, metabolism and cellular damage, using a newly designed automated hypoxia simulation device that features exceptional accuracy and good stability. The clams exhibited strong tolerance to hypoxia as the 20-day LC₅₀ for dissolved oxygen (DO) was estimated to be 0.57 mg L^-1, and the LT₅₀ at 0.5 mg L^-1 DO was 422 hours. Adaptations included fewer buried clams and a depressed metabolism, while the unexpected rise in the activities of key enzymes involved in glycolysis may indicate a diverse strategy of shellfish under hypoxia. Cellular damage was observed as collapse of the mitochondrial cristae and both cellular and mitochondrial vacuolization. This multi-level study complements and updates our knowledge of the effects of hypoxia on marine benthos, by improving our understanding of the potential for marine ecological transformation under hypoxic conditions and providing useful information for Manila clam farming.

Sulfur, iron, and phosphorus geochemistry in an intertidal mudflat impacted by shellfish aquaculture

Dissolved sulfide, iron (Fe), and phosphorus (P) in a mudflat (Jiaozhou Bay, China) impacted by shellfish aquaculture were measured in situ by the diffusive gradients in thin films (DGT) technique. A combination of porewater and solid-phase chemistry was used to characterize the interplays of Fe and S, and their control on P mobilization. Below the subsurface layer, two times higher fluxes (F_DGT) of dissolved Fe²⁺ from porewater to the DGT device than those of dissolved sulfide indicate that dissimilatory iron reduction (DIR) dominates over sulfate reduction (SR). Spatial coupling of dissolved Fe²⁺ and P points to P release driven mainly by reductive dissolution of Fe. Much higher F_DGT values of dissolved Fe²⁺ relative to dissolved P imply that oxidative regeneration of Fe oxides at the sediment-water interfaces (SWIs) of the transitional mudflat serves as an effective "iron curtain" of upward diffusing P. In the mudflat sediments of DIR prevalence, the accumulation of total reduced inorganic sulfur (TRIS) is dampened, which can largely ascribed to enhanced oxidative loss of sulfide and/or limited availability of degradable organic carbon in the dynamic regimes. Low dissolved sulfide concentrations in the sediments leave the majority of reactive Fe unsulfidized and thus abundantly available to buffer newly produced sulfide.

Perception of Climate Change in Shrimp-Farming Communities in Bangladesh: A Critical Assessment

Local contexts as well as levels of exposure play a substantial role in defining a community’s perception of climate and environmental vulnerabilities. In order to assess a community’s adaptation strategies, understanding of how different groups in that community comprehend climate change is crucial. Public risk perception is important as it can induce or confine political, economic, and social actions dealing with particular hazards. Climate change adaptation is a well-established policy discourse in Bangladesh that has made its people more or less aware of it. Similarly, shrimp-farming communities in southwestern Bangladesh understand environmental and climate change in their own ways. In order to understand how the shrimp-farming communities in coastal Bangladesh perceive current climate instabilities, we conducted a qualitative study in shrimp-farming villages in coastal Bangladesh where about 80% of commercial shrimp of the country is cultivated. We compared farmers’ perceptions of local climate change with existing scientific knowledge and found remarkable similarities. Our assessment shows that at least two factors are critical for this outcome: coastal people’s exposure to and experience of frequent climate extremes; and a radical approach to defining climate regimes in Bangladesh by various stakeholders and the media, depicting anthropogenic global warming as a certainty for the country. Thus, a convergence of scientific construct and sociocultural construct construes the level of awareness of the general public about climate change.

Effects of T-2 toxin on histopathology, fatty acid and water distribution of shrimp (Litopenaeus vannamei) muscle

T-2 toxin (T-2), one of the naturally occurring mycotoxins, often accumulates in aquatic animals from contaminated feed. Shrimp (n = 30 per group) were fed with different concentrations (0, 0.5, 1.5, 4.5 and 13.5 mg kg^-1) of T-2 for 20 days. Changes in histopathology, fatty acid and water distribution of shrimp muscle were analyzed. Histopathology of shrimp muscle showed dose-dependent marked degenerative and necrotic changes on exposure to dietary T-2. The T-2 significantly (P < 0.05) affected the muscle fatty acid composition. ∑SFA, ∑MUFA and ∑PUFA initially decreased and then increased slowly in the high-dosed groups. C16:0, C18:1n-9 and C18:2n-6 were the main saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA), respectively. Also, T-2 significantly affected water distribution in shrimp muscle. High doses of T-2 reduced free water content, resulting in a reduction in the water holding capacity and hence changes to the shrimp muscle quality. Collectively, these results illustrated that T-2 significantly affects the fatty acid and water distribution, and also muscle histopathology, all of which would result in a reduction in the quality and nutritional value of shrimp.

Leave or stay? Video-logger revealed foraging efficiency of humpback whales under temporal change in prey density

Central place foraging theory (CPF) has been used to predict the optimal patch residence time for air-breathing marine predators in response to patch quality. Humpback whales (Megaptera novaeangliae) forage on densely aggregated prey, which may induce drastic change in prey density in a single feeding event. Thus, the decision whether to leave or stay after each feeding event in a single dive in response to this drastic change, should have a significant effect on prey exploitation efficiency. However, whether humpback whales show adaptive behavior in response to the diminishing prey density in a single dive has been technically difficult to test. Here, we studied the foraging behavior of humpback whales in response to change in prey density in a single dive and calculated the efficiency of each foraging dive using a model based on CPF approach. Using animal-borne accelerometers and video loggers attached to whales, foraging behavior and change in relative prey density in front of the whales were successfully quantified. Results showed diminishing rate of energy intake in consecutive feeding events, and humpback whales efficiently fed by bringing the rate of energy intake close to maximum in a single dive cycle. This video-based method also enabled us to detect the presence of other animals around the tagged whales, showing an interesting trend in behavioral changes where feeding duration was shorter when other animals were present. Our results have introduced a new potential to quantitatively investigate the effect of other animals on free-ranging top predators in the context of optimal foraging theory.

Association of fried food consumption with all cause, cardiovascular, and cancer mortality: prospective cohort study

OBJECTIVE

To examine the prospective association of total and individual fried food consumption with all cause and cause specific mortality in women in the United States.

DESIGN

Prospective cohort study.

SETTING

Women's Health Initiative conducted in 40 clinical centers in the US.

PARTICIPANTS

106 966 postmenopausal women aged 50-79 at study entry who were enrolled between September 1993 and 1998 in the Women's Health Initiative and followed until February 2017.

MAIN OUTCOME MEASURES

All cause mortality, cardiovascular mortality, and cancer mortality.

RESULTS

31 558 deaths occurred during 1 914 691 person years of follow-up. For total fried food consumption, when comparing at least one serving per day with no consumption, the multivariable adjusted hazard ratio was 1.08 (95% confidence interval 1.01 to 1.16) for all cause mortality and 1.08 (0.96 to 1.22) for cardiovascular mortality. When comparing at least one serving per week of fried chicken with no consumption, the hazard ratio was 1.13 (1.07 to 1.19) for all cause mortality and 1.12 (1.02 to 1.23) for cardiovascular mortality. For fried fish/shellfish, the corresponding hazard ratios were 1.07 (1.03 to 1.12) for all cause mortality and 1.13 (1.04 to 1.22) for cardiovascular mortality. Total or individual fried food consumption was not generally associated with cancer mortality.

CONCLUSIONS

Frequent consumption of fried foods, especially fried chicken and fried fish/shellfish, was associated with a higher risk of all cause and cardiovascular mortality in women in the US.

Proximate, fatty acids and metals in edible marine bivalves from Italian market: Beneficial and risk for consumers health

Seafood is recognized as a healthy food choice due to high contents of essential nutrients, including polyunsaturated fatty acids (PUFAs) of the n-3 family. However, seafood is often contaminated by toxic compounds, which have adverse effects on human health. The aim of this study was to provide information about the percentage of edible part, condition index and the benefit and risk for human consumers health associated to the consumption of eight bivalve species (Flexopecten glaber, Mimachlamys varia, Modiolus barbatus, Mytilus galloprovincialis, Ostrea edulis, Ruditapes philippinarum, Solen marginatus and Venus verrucosa) of high commercial value, purchased from Taranto local fish markets. High percentage of edibility and condition index were found in all analysed species. The relatively high protein content, low levels of lipid and high percentage of healthy n-3 PUFAs make M. varia, O. edulis, S. marginatus, M. galloprovincialis, M. barbatus more suitable for benefit to consumers. Provisional tolerable weekly intake and hazard index calculated on the basis of trace metals in edible tissues, indicated specific recommendations for a responsible daily consumption of shellfish. For the most part of studied species, the estimated balance between beneficial and risk for consumers recommend a daily portion (RDP) lesser of 60 g/person/day than M. galloprovincialis, O. edulis and R. philippinarum (≥60 g/person/day). Careful risk-benefit considerations should promote seafood consumption while minimizing exposure to toxic contaminants.

Changes in the biochemical and nutrient composition of seafood due to ocean acidification and warming

Ocean acidification and warming may threaten future seafood production, safety and quality by negatively impacting the fitness of marine species. Identifying changes in nutritional quality, as well as species most at risk, is crucial if societies are to secure food production. Here, changes in the biochemical composition and nutritional properties of the commercially valuable oysters, Magallana gigas and Ostrea edulis, were evaluated following a 12-week exposure to six ocean acidification and warming scenarios that were designed to reflect the temperature (+3 °C above ambient) and atmospheric pCO₂ conditions (increase of 350-600 ppm) predicted for the mid-to end-of-century. Results suggest that O. edulis, and especially M. gigas, are likely to become less nutritious (i.e. containing lower levels of protein, lipid, and carbohydrate), and have reduced caloric content under ocean acidification and warming. Important changes to essential mineral composition under ocean acidification and warming were evident in both species; enhanced accumulation of copper in M. gigas may be of concern regarding consumption safety. In light of these findings, the aquaculture industry may wish to consider a shift in focus toward species that are most robust to climate change and less prone to deterioration in quality, in order to secure future food provision and socio-economic benefits of aquaculture.

Immunoecology of the short neck clam Paphia malabarica (Chemnitz, 1782) in a tropical monsoon-influenced estuary

Understanding the variability in organism's immunological response is crucial for predicting changes at population or community level. The present study investigated the immunoecology of a commercially valuable clam Paphia malabarica in a tropical monsoon-influenced estuary. Clams were collected monthly during a year cycle, which coincided with pre-monsoon (February-May), monsoon (June-September) and post-monsoon seasons (October-January). For assessment of immune functioning, selected hemocyte parameters (total hemocyte concentration, hemocyte mortality, lysosomal content, esterase activity, reactive oxygen species production, and phagocytic activity) were analyzed using flow cytometry. Simultaneously, clam's condition index, nutrients, chlorophyll a, dissolved oxygen, pH, temperature and bacterial density were also measured at the sampling site. Our results exhibited seasonal patterns in hemocyte functioning with the highest activity during the pre-monsoon season (suggestive of a suitable harvesting period) and lowest during monsoon (suggestive of a critical biological period). The critical biological period for P. malabarica was marked with compromised immune parameters inflicted by low salinity, food availability, and possibly high bacterial abundance. Also, the involvement of reproductive stress altering the hematological functioning in P. malabarica cannot be ruled out. Nutrients, dissolved oxygen, pH and temperature could not explain much of the hemocyte variability. The present study has further validated the usefulness of hemocyte as a suitable marker for understanding immunoecology of P. malabarica which is of prime importance, especially in a monsoon-influenced tropical estuarine environment. The findings of our research will be constructive in monitoring natural as well as cultivated bivalve populations of economic and ecological relevance.

Oyster disease in a changing environment: Decrypting the link between pathogen, microbiome and environment

Shifting environmental conditions are known to be important triggers of oyster diseases. The mechanism(s) behind these synergistic effects (interplay between host, environment and pathogen/s) are often not clear, although there is evidence that shifts in environmental conditions can affect oyster immunity, and pathogen growth and virulence. However, the impact of shifting environmental parameters on the oyster microbiome and how this affects oyster health and susceptibility to infectious pathogens remains understudied. In this review, we summarise the major diseases afflicting oysters with a focus on the role of environmental factors that can catalyse or amplify disease outbreaks. We also consider the potential role of the oyster microbiome in buffering or augmenting oyster disease outbreaks and suggest that a deeper understanding of the oyster microbiome, its links to the environment and its effect on oyster health and disease susceptibility, is required to develop new frameworks for the prevention and management of oyster diseases.

Fate of carotenoid-producing Bacillus aquimaris SH6 colour spores in shrimp gut and their dose-dependent probiotic activities

Bacillus aquimaris SH6 spores produce carotenoids that are beneficial to white-leg shrimp (Litopenaeus vannamei) health. However, the optimal dose and mechanisms behind these effects are not well understood. We investigated the fate of SH6 spores in the gut of L. vannamei. Shrimp were divided into six groups administrated with either feed only (negative control) or SH6 spores at 5 × 106 CFU/g pellet (high dose, SH6 spore-H group), 1 × 106 CFU/g pellet (medium dose, SH6 spore-M group), 2 × 105 CFU/g pellet (low dose, SH6 spore-L group), astaxanthin at 0.5 mg/g pellet (Carophyll group), or carotenoids from SH6 vegetative cells at 5 μg/g pellet (SH6 carotenoid group). The growth rate was highest in SH6 spore-H (3.38%/day), followed by SH6 spore-M (2.84%/day) and SH6 spore-L (2.25%/day), which was significantly higher than the control (1.45%/day), Carophyll (1.53%/day) or SH6 carotenoid (1.57%/day) groups. The astaxanthin levels (1.9-2.0 μg/g shrimp) and red-colour scores (21-22) in SH6 spore-H/M were higher than the control (astaxanthin: 1.2 μg/g shrimp; red score: 20) or SH6 spore-L, but lower than the Carophyll and SH6 carotenoids. Feeding with medium and high doses of SH6 spores after 28 days resulted in respective 1.3-2-fold increases in phenol oxidase activity and 8-9 fold increases in Rho mRNA expression compared to the control and low dose group. The live-counts of SH6 in the gut gradually increased during the 28-day feeding period with SH6 spores at different concentrations, starting from 4.1, 8.2, and 5.4 × 104 CFU/g gut at day 1 and reaching 5.3, 5.1, and 4.4 × 105 CFU/g gut in the SH6-H/M/L groups, respectively, at day 28. Gut microbiota became more diversified, resulting in a 2-8-fold increase in total bacterial live-counts compared to the controls. SH6 spore germination was detected by measuring the mRNA expression of a specific sequence coding for SH6 amylase at 4 h, reaching saturation at 24 h. Our results confirm that SH6 spores colonize and germinate in the gut to improve the microbial diversity and boost the immune system of shrimp, exhibiting beneficial effects at >1 × 106 CFU/g pellet.

DISTRIBUTION AND BIOACCUMULATION OF 210Po AND 210Pb IN ABIOTIC AND BIOTIC COMPONENTS OF THE BAY OF BENGAL

Marine environment is enriched source of heavy minerals associated with radionuclides which are largely responsible for human exposure to radiation. Bay of Bengal is one among the important marine ecosystems in the world because of its high biodiversity. The aim of this work was to generate a comprehensive data on distribution and bioaccumulation of 210Po and 210Pb in marine environment of the Bay of Bengal. For this water and sand samples (10 stations), shellfishes (21 species) and fishes (43 species) were collected and the concentrations of 210Po and 210Pb were measured by radiochemical separation followed by alpha counting method using ZnS(Ag) detector. 210Pb concentration in the marine water (mean: 7.6 ± 3.31 mBq l-1) is always higher than 210Po (mean: 4.1 ± 1.97 mBq l-1). The mean 210Po and 210Pb concentration in sand was 5.2 ± 1.87 and 3.1 ± 1.20 Bq kg-1, respectively; indicating that 210Po concentrations in the sand sample is always higher than that of 210Pb. The concentration of both 210Po and 210Pb depends on grain size of the sand. Surface samples of depth 0-10 cm recorded maximum 210Po (6.37 Bq kg-1) and 210Pb (4.07 Bq kg-1) concentration. The concentrations of 210Po and 210Pb in biota are following decreasing order: Oyster > Clam > Squid > Crab > Prawn > Fish. The committed effective dose rate calculated for shellfish species maintained a higher range of 81.0-281.2 μSv y-1. However, dose transfer rate from fish species fluctuated from 14.4 to 165.6 μSv y-1and this indicated that fish is radiologically safe as compared to shellfish.

Metal accumulation in the marine bivalve, Marcia optima collected from the coastal area of Phuket Bay, Thailand

Metal contamination in seafood has raised public health concerns, especially for local residents who live in coastal areas. In this study, the levels of cadmium (Cd), lead (Pb), mercury (Hg), and zinc (Zn) were determined in the marine bivalve, Marcia optima, as well as in water, and sediment samples collected from the coastal area of Phuket Bay, Thailand. The results showed that metal concentrations in sediments (4.05-7.14, 16.68-18.13, 164-213 mg kg^-1 for Cd, Pb, and Zn, respectively) and water samples (0.16-0.44, 0.15-0.26, and 0.32-0.48 mg L^-1 for Cd, Pb, and Zn, respectively) were below the threshold effects concentration of the sediment quality guidelines for adverse effects to occur and the marine water quality standards of Thailand. A human risk assessment was performed and the results showed that the risks associated with M. optima consumption at Saphan Hin and Paklok were negligible for most of the metals studied, with the maximum estimated daily intake value being observed for Zn (0.00663 mg kg^-1 per day) at Saphan Hin. In addition, Cd, Zn, Pb, and Hg would be unlikely to pose a risk to human health with a hazard quotient of less than 1, with only the bioaccumulation factor of Zn being detectable in both locations (0.034 and 0.026 at Saphan Hin and Paklok, respectively). However, continuous monitoring is encouraged to prevent the risks associated with the consumption of metal-contaminated seafood.

Refining a Nordmøre-grid bycatch reduction device for the Spencer Gulf penaeid-trawl fishery

Incremental refinements were made to a generic Nordmøre-grid to minimise bycatches of blue swimmer crabs Portunus armatus and giant cuttlefish Sepia apama, while maintaining catches of western king prawns Melicertus latisulcatus in the Spencer Gulf penaeid-trawl fishery. These refinements involved varying bar spaces, escape-exit areas and guiding-panel lengths, and were compared against a conventional trawl. Catches of teleosts and M. latisulcatus largely remained unaffected by the changes. Maximum reductions in P. armatus and S. apama bycatches (both ~90%) were achieved with a Nordmøre-grid comprising 38-mm bar spaces, 0.81- or 1.05-m² escape exits and a 2.7-m guiding panel. Catching fewer P. armatus should reduce abrasion and crushing of M. latisulcatus in the codend and so increase the value of this targeted species. While noting some unresolved operational concerns, these results demonstrate the potential improvements in selectivity in this fishery using a Nordmøre-grid, primarily by mechanical separation.

SeaGIS Abruzzo: A publicly available atlas of marine uses and natural resources in the Adriatic Sea Region

In the Adriatic Sea, the European Union supported a cross-border cooperation research program, during which digital spatial data on shellfish production and relaying areas, regulated conditions on fishing activities, protected areas and restocking structures, administrative boundaries and sea bottom characteristics, were collated from digital repositories in various institutions and paper documents. A web-based geographical information system was developed to share data of the sea facing the Abruzzi region and to explore the spatial distribution of marine resources and maritime activities, thus focussing and facilitating fisheries management and providing a potential support to the regional planning of resource exploitation.

Utilization of freshwater mussel (Lamellidens marginalis) for the isolation of proteins through pH shift processing: characterization of isolates

Study was conducted to use underutilized freshwater mussel (Lamellidens marginalis) for the recovery of proteins using pH shift method and to study the functionality and characteristics of the recovered isolates. From the pH range tested (pH 2.0-13.0), maximum protein yields were obtained during solubilization at pH 2.0 and pH 13.0 (p < 0.05). During the protein recovery process, pH 13.0 was found to have minimal effect on proteins resulting in higher protein yields compared to pH 2.0. Isolates obtained by both acidic and alkaline solubilization processes had low stability and poor gel network. Total lipid content, total myoglobin, and pigment contents were reduced significantly (p < 0.05) during pH shift processing, resulting in whiter protein isolates and protein gels. All the essential amino acids were present in the isolates recovered by acid and alkaline solubilization, indicating the complete recovery of amino acids. No microbial counts were observed in any of the isolates prepared using acid and alkaline-aided processing. Acid and alkaline solubilization (pH shift) process was found to be promising for the recovery of proteins from underutilized freshwater mussel thus by reducing the supply demand gap.

Production of domoic acid from large-scale cultures of Pseudo-nitzschia multiseries: A feasibility study

The commercial demand for domoic acid (DA), the phycotoxin responsible for Amnesic Shellfish Poisoning, is currently met by extraction from a diminishing supply of stockpiled contaminated mussels (Mytilus edulis). As this supply becomes scarce, a more reliable source is needed. Purification of the toxin from an algal source would be easier and more economical than from shellfish tissue if algal growth and yield of toxin were maximized. This project was initiated to determine if DA could be produced using large-scale semi-continuous algal cultures, which should reduce labour and shorten the time required for biomass production. Pseudo-nitzschia multiseries was grown in 300-L fibreglass photobioreactors called a Brite-Box™. The effect of temperature and nutrient depletion on the yield of DA by P. multiseries was examined. A decline in maximum cell number without a substantial increase in cellular DA was associated with increased temperature. Maximum total cellular DA (8.8 pg cell^-1) was achieved at 20 °C. Semi-continuous culture of P. multiseries is accompanied by increasing amounts of DA lost to the medium. The process was deemed to be feasible for growing P. multiseries but methods to recover this extracellular DA are necessary for this process to be economical.

Anomalocardia brasiliana shellfish shells as a novel and ecofriendly adsorbent of Nylosan Brilliant Blue acid dye

Malacoculture waste (Anomalocardia brasiliana) shellfish shells (ABSS) were evaluated as adsorbents of Nylosan Brilliant Blue (NBB) acid dye. The ABSS were thermally activated at 1,000 °C for 10 h and then characterized by Fourier-transform infrared spectroscopy, analysis of specific surface area (BET), X-ray diffraction (XRD), and scanning electron microscopy. Point of zero charge (PZC) analysis of ABSS verified pH_PZC 13.0. The study of kinetics showed that the pseudo-second-order model fit the experimental data best and the system reached equilibrium within 5 min. Adsorption isotherms followed the Langmuir-Freundlich isotherm and ABSS reached an outstanding maximum adsorption capacity of 405 mg·g^-1 under the following optimum conditions: pH 12.4, 303 K, 450 rpm, 2.0 g of adsorbent, and 150 μm average particle size. These conditions were obtained after a previous statistical analysis of the variables. Enthalpy and Gibbs energy obtained in the thermodynamics experiments were -23.79 kJ·mol^-1 and -4.07 kJ·mol^-1, respectively. These parameters confirm that the process is exothermic, spontaneous, and indicative of the physical nature of the adsorption. The adsorption of NBB onto ABSS tended to be more favorable at a lower temperature. Low value of enthalpy suggested that weak binding forces, such as electrostatic interactions, govern the sorption mechanism. ABSS high availability in the environment, its low toxicity and high efficiency make it a promising ecofriendly adsorbent of textile dyes.

A decade and a half of Pseudo-nitzschia spp. and domoic acid along the coast of southern California

Blooms of the marine diatom genus Pseudo-nitzschia that produce the neurotoxin domoic acid have been documented with regularity along the coast of southern California since 2003, with the occurrence of the toxin in shellfish tissue predating information on domoic acid in the particulate fraction in this region. Domoic acid concentrations in the phytoplankton inhabiting waters off southern California during 2003, 2006, 2007, 2011 and 2017 were comparable to some of the highest values that have been recorded in the literature. Blooms of Pseudo-nitzschia have exhibited strong seasonality, with toxin appearing predominantly in the spring. Year-to-year variability of particulate toxin has been considerable, and observations during 2003, 2006, 2007, 2011 and again in 2017 linked domoic acid in the diets of marine mammals and seabirds to mass mortality events among these animals. This work reviews information collected during the past 15 years documenting the phenology and magnitude of Pseudo-nitzschia abundances and domoic acid within the Southern California Bight. The general oceanographic factors leading to blooms of Pseudo-nitzschia and outbreaks of domoic acid in this region are clear, but subtle factors controlling spatial and interannual variability in bloom magnitude and toxin production remain elusive.

Antioxidant Activity of Extract from the Cephalothorax of Fenneropenaeus chinensis

We investigated the antioxidant activity of taurine rich water extract from the cephalothorax of Fenneropenaeus chinensis (FCC). The antioxidant potency of water extract from FCC was assessed using various assay methods, such as DPPH (1,1-diphenyl-2-picrylhydrazyl), alkyl radical scavenging activity, ABTS (2,2'-azinobis (3-ethylbenzothiazoline 6-sulfonic acid ammonium salt)) radical scavenging activity and Ferric reducing antioxidant power (FRAP) assay. The DPPH and alkyl radical scavenging activities of FCC were dose-dependently increased. The lipid peroxidation was estimated using ferric thiocyanate (FTC) assay and thiobarbituric acid (TBA) methods. However, a higher lipid peroxidation activity was observed in TBA method than FTC method. The results of the present study suggested that the FCC extract potentially scavenged the free radical and reduced oxidative stress. Therefore, the present study is concluded that the FCC extract could be a potential source of antioxidant activity.

C-H Hydroxylation in Paralytic Shellfish Toxin Biosynthesis

The remarkable degree of synthetic selectivity found in Nature is exemplified by the biosynthesis of paralytic shellfish toxins such as saxitoxin. The polycyclic core shared by saxitoxin and its relatives is assembled and subsequently elaborated through the installation of hydroxyl groups with exquisite precision that is not possible to replicate with traditional synthetic methods. Here, we report the identification of the enzymes that carry out a subset of C-H functionalizations involved in paralytic shellfish toxin biosynthesis. We have shown that three Rieske oxygenases mediate hydroxylation reactions with perfect site- and stereoselectivity. Specifically, the Rieske oxygenase SxtT is responsible for selective hydroxylation of a tricyclic precursor to the famous natural product saxitoxin, and a second Rieske oxygenase, GxtA, selectively hydroxylates saxitoxin to access the oxidation pattern present in gonyautoxin natural products. Unexpectedly, a third Rieske oxygenase, SxtH, does not hydroxylate tricyclic intermediates, but rather a linear substrate prior to tricycle formation, rewriting the biosynthetic route to paralytic shellfish toxins. Characterization of SxtT, SxtH, and GxtA is the first demonstration of enzymes carrying out C-H hydroxylation reactions in paralytic shellfish toxin biosynthesis. Additionally, the reactions of these oxygenases with a suite of saxitoxin-related molecules are reported, highlighting the substrate promiscuity of these catalysts and the potential for their application in the synthesis of natural and unnatural saxitoxin congeners.

GIS-based multi-criteria site selection for zebra mussel cultivation: Addressing end-of-pipe remediation of a eutrophic coastal lagoon ecosystem

Farming of shellfish and seaweeds is a tested tool for mitigating eutrophication consequences in coastal environments, however as many other marine economic activities it should be a subject of marine spatial planning for designating suitable sites. The present study proposes site selection framework for provisional zebra mussel farming in a eutrophic lagoon ecosystem, aimed primarily at remediation purposes. GIS-based multi-criteria approach was applied, combining data from empirical maps, numerical models and remote sensing to estimate suitability parameters. Site selection and prioritisation of suitable areas considered 15 environmental and socio-economic criteria, which contributed to 4 optimisation models (settlement, growth and survival of mussels, environmental and socio-economic) and 3 predefined scenarios representing provisional goals of mussel cultivation: spat production, biomass production and bioremediation. The relative importance of each criterion was assessed utilizing the Analytical Hierarchy Process. Site suitability index was calculated and the final result of the site selection analysis was summarized for 3 scenarios and overall suitability map. Four suitability classes (unsuitable, least, moderately and most suitable) were applied, and 3 most suitable zones for provisional zebra mussel cultivation with 12 candidate sites were selected accordingly. The integrated approach presented in this study can be adjusted for designating zebra mussel farming sites in other estuarine lagoon ecosystems, or cultivation of other mussel species for bioremediation purposes. The analytical framework and the workflow designed in this study are also adoptable for addressing other aquaculture-related spatial planning issues.