The occurrence of lipophilic toxins in shellfish from the Middle Adriatic Sea.

The first survey of the phycotoxin profile in mussels (Mytilus galloprovincialis) from the coastal waters of Bosnia and Herzegovina (The Bay of Neum, Middle Adriatic Sea) in correlation to the Makarska City Bay (Croatia, Middle Adriatic Sea) was conducted in 2017. Throughout the monitoring period, occasions of gymnodimine (GYM) and azaspiracid (AZA2) shellfish toxicity were recorded in concentrations that do not endanger human health. The occurrence of yessotoxins (YTXs), the most common toxins found in the Adriatic Sea, was correlated to the presence of the Gonyaulax species, a potential source of YTX. The DSP group of toxins is represented by the ester-OA. Phytoplankton analysis confirmed the presence of dinoflagellates from the Prorocentrum genus, a species associated with DSP toxicity. Occurrence frequency and variability of toxin composition were investigated in conjunction to physico-chemical parameters in the surrounding sea water. In the central Adriatic Sea, the infestation period ranges in general from June to August. However, the depuration phase extended beyond September in the Bay of Neum, increasing the length of the decontamination period.

Perceived socio-economic impacts of the marbled crayfish invasion in Madagascar.

The negative environmental and economic impacts of many invasive species are well known. However, given the increased homogenization of global biota, and the difficulty of eradicating species once established, a balanced approach to considering the impacts of invasive species is needed. The marbled crayfish (Procambarus virginalis) is a parthenogenetic freshwater crayfish that was first observed in Madagascar around 2005 and has spread rapidly. We present the results of a socio-economic survey (n = 385) in three regions of Madagascar that vary in terms of when the marbled crayfish first arrived. Respondents generally considered marbled crayfish to have a negative impact on rice agriculture and fishing, however the animals were seen as making a positive contribution to household economy and food security. Regression modeling showed that respondents in regions with longer experience of marbled crayfish have more positive perceptions. Unsurprisingly, considering the perception that crayfish negatively impact rice agriculture, those not involved in crayfish harvesting and trading had more negative views towards the crayfish than those involved in crayfish-related activities. Food preference ranking and market surveys revealed the acceptance of marbled crayfish as a cheap source of animal protein; a clear positive in a country with widespread malnutrition. While data on biodiversity impacts of the marbled crayfish invasion in Madagascar are still completely lacking, this study provides insight into the socio-economic impacts of the dramatic spread of this unique invasive species. "Biby kely tsy fantam-piaviana, mahavelona fianakaviana" (a small animal coming from who knows where which supports the needs of the family). Government worker Analamanga, Madagascar.

Health risk assessment related to pinnatoxins in French shellfish.

Pinnatoxins (PnTXs) are a group of emerging marine biotoxins produced by the benthic dinoflagellate Vulcanodinium rugosum, currently not regulated in Europe or in any other country in the world. In France, PnTXs were detected for the first time in 2011, in mussels from the Ingril lagoon (South of France, Mediterranean coast). Since then, analyses carried out in mussels from this lagoon have shown high concentrations of PnTXs for several months each year. PnTXs have also been detected, to a lesser extent, in mussels from other Mediterranean lagoons and on the Atlantic and Corsican coasts. In the French data, the main analog is PnTX G (low levels of PnTX A are also present in some samples). No cases of PnTXs poisoning in humans have been reported so far in France or anywhere else in the world. In mice, PnTXs induce acute neurotoxic effects, within a few minutes after oral administration. Clinical signs of toxicity include decreased mobility, paralysis of the hind legs, tremors, jumps and breathing difficulties leading to death by respiratory arrest at high doses. The French agency for food safety (ANSES) recently conducted a review of the state of knowledge related to PnTXs and V. rugosum. Based on (i) the clinical signs of toxicity in mice, (ii) the mode of action of PnTXs as nicotinic acetylcholine receptor competitive antagonists and (iii) knowledge on drugs and natural toxins with PnTX-related pharmacology, potential human symptoms have been extrapolated and proposed. In this work, a provisional acute benchmark value for PnTX G of 0.13 µg/kg bw per day has been derived from an oral acute toxicity study in mice. Based on this value and a large shellfish meat portion size of 400g, a concentration lower than 23 µg PnTX G/kg shellfish meat is not expected to result in adverse effects in humans. ANSES recommends taking into account PnTXs in the French official monitoring program for shellfish production and identified data gaps to refine health risk assessment.

Contamination status of lipophilic marine toxins in shellfish samples from the Bohai Sea, China.

Lipophilic marine toxins in shellfish pose significant threats to the health of seafood consumers. To assess the contamination status of shellfish by lipophilic marine toxins in the Bohai Sea, nine species of shellfish periodically collected from five representative aquaculture zones throughout a year were analyzed with a method of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Lipophilic marine toxins, including okadaic acid (OA), dinophysistoxin-1 (DTX1), pectenotoxin-2 (PTX2), yessotoxin (YTX), homo-yessotoxin (homo-YTX), azaspiracids (AZA2 and AZA3), gymnodimine (GYM), and 13-desmethyl spirolide C (13-DesMe-C), were detected in more than 95 percent of the shellfish samples. Toxins PTX2, YTX, 13-DesMe-C and GYM were predominant components detected in shellfish samples. Scallops, clams and mussels accumulated much higher level of lipophilic marine toxins compared to oysters. Toxin content in shellfish samples collected from different sampling locations showed site-specific seasonal variation patterns. High level of toxins was found during the stages from December to February and June to July in Hangu, while from March to April and August to September in Laishan. Some toxic algae, including Dinophysis acuminata, D. fortii, Prorocentrum lima, Gonyaulax spinifera and Lingulodinium polyedrum, were identified as potential origins of lipophilic marine toxins in the Bohai Sea. The results will offer a sound basis for monitoring marine toxins and protecting the health of seafood consumers.

Do the Escherichia coli European Union shellfish safety standards predict the presence of Arcobacter spp., a potential zoonotic pathogen?

The genus Arcobacter comprises Campylobacter-related species, considered zoonotic emergent pathogens, the presence of which in water has been associated with fecal pollution. Discharges of fecal polluted water into the sea have been considered as one of the main reasons for the presence of Arcobacter in shellfish, and this may represent a risk for public health. In this study, the European Union shellfish food safety criteria based on levels of Escherichia coli were studied in relation to their capacity to predict the presence of Arcobacter species. In addition, the accumulation factor (AF) that measures the concentration ratio between the microbes present in the shellfish and in the water, was also studied for both bacteria. The results show that the presence of E. coli correlated with the presence of the potentially pathogenic species A. butzleri and A. cryaerophilus. However, in 26.1% of the shellfish samples (corresponding to those taken during summer months) E. coli failed to predict the presence of, for instance A. butzleri and A. skirrowii, among other species. In the rest of the samples a significant correlation between the concentration of E. coli and Arcobacter spp. (mussels and oyster; R2=0.744) was found. This study indicates that the presence of E. coli can predict the presence of pathogenic Arcobacter species in shellfish samples harvested from water with temperatures lower than 26.2°C. Consumption of shellfish collected at higher temperatures which may not be permissive to the growth of E. coli but does allow growth of Arcobacter spp., may represent a risk for consumers.

Cryptosporidium spp. Contamination in Perna perna Mussels Destined for Human Consumption in Southeastern Rio de Janeiro, Brazil.

Cryptosporidium spp. has been recognized as an important pathogen. As bivalve mollusks are noted as potential sources of several pathogens due to their consumption as foodstuffs, the aim of this study was to investigate the occurrence of Cryptosporidium spp. oocysts in Perna perna mussels and in seawater samples from a mussel farm in Southeastern Brazil, where mussels are grown directly in the sea, attached to ropes. Oocysts were observed by microscopy and confirmed by an enzyme-linked immunosorbent assay. Oocysts were present in mussel gills and GI tracts, as well as in the seawater. Of the 100 females, 10% and 11% showed contaminated GI tracts and gills, respectively, while this rate was lower in males, at 5% and 8.9%. Oocysts were present in higher amounts in the GI tract compared to gills and water. Contamination of the study area is apparent, leading to public health risks. More in-depth studies are needed, including molecular investigations, to identify Cryptosporidium species in mussels, as well as the implementation of monitoring actions in animals destined for human consumption.

Arsenic speciation in fish and shellfish from the North Sea (Southern bight) and Açu Port area (Brazil) and health risks related to seafood consumption.

In North Sea and Port Açu (Brazil) coastal areas, high arsenic (As) concentrations were observed in water, soil and sediments. Therefore, the impact of this contamination on fish and shellfish species bought from local fishermen was studied. Total As was assessed with ICP-OES (Brazil) and ICP-MS (North Sea) after microwave digestion. Toxic As was assessed with liquid chromatography-ICP-MS (Brazil) and hydride generation-atomic fluorescence spectrometry (North Sea). All analytical methods comply with Quality Assurance/Quality Control procedures. Several fish species have average Total As concentrations above 1 µg g-1 wet weight (ww), but the highest concentrations are found in less spotted dogfish, lemon sole and whelks from the North Sea, with respectively 50, 49 and 50 µg g-1 ww. High Total As concentrations correspond to high Toxic As concentrations, except for scallops having increased Toxic As concentrations. Toxic As fractions are highest in scallops (almost 10%) but rarely exceeds 2% in all other species. Liver samples were only analyzed in ray, dogfish and catfish and their Toxic As fractions are between 2 and 4 times higher than in muscle. For a consumption of 150 g of seafood, only 3 samples exceed the provisional total daily intake of 2 µg kg-1 bw, however, cancer risks are non-negligible. Using mean Toxic As concentrations for each of the different fish and shellfish species studied, Lifetime Cancer Risk values at the actual global seafood consumption rate of 54 g day-1 are above 10-4 for whelks, scallops, dogfish, ray and lemon sole.

Bioaccumulation of trace metals in farmed pacific oysters Crassostrea gigas from SW Gulf of California coast, Mexico.

The aim of the study was to evaluate the bioavailability of trace metals (Chromium, Copper, Nickel, Lead, Zinc, Cadmium, Arsenic, and Mercury) in the commercially consumed Crassostrea gigas oysters collected over a 12-month growth period (2011-12) from an experimental cultivation farm in La Pitahaya, Sinaloa State, Mexico. Sediment and water samples were also collected from four different zones adjacent to the cultivation area to identify the concentration patterns of metals. The results revealed that sewage disposals, fertilizers used for agricultural practices and shrimp culture are the major sources for the enrichment of certain toxic metals. The metal concentrations in oysters presented a decreasing order of abundance (all values in mg Kg-1): Zn (278.91 ± 93.03) > Cu (63.13 ± 31.72) > Cr (22.29 ± 30.23) > Cd (14.54 ± 4.28) > Ni (9.41 ± 11.33) > Pb (2.22 ± 1.33) > As (0.58 ± 0.91) > Hg (0.04 ± 0.06). Bioconcentration Factor (BCF) and Biota Sediment Accumulation Factor (BSAF) exhibited that C. gigas in the region are strong accumulators for Zn and Cd respectively. Thus, the present study proves to fulfill the gap in understanding the rate of bioaccumulation of metals in C. gigas which is regarded as the most sought after oyster species globally.

Contamination status of arsenic in fish and shellfish from three river basins in Ghana.

Fish and shellfish are regularly consumed and sold in Ghana, yet studies on arsenic pollution in Ghana are limited largely to ground water. This study evaluated arsenic concentrations in seven species of shellfish and 10 species of fish inhabiting the mouth of Ankobra, Densu and Volta basins in Ghana and assessed the public health implications. Arsenic levels varied from 0.2 to 2.2 mg L-1 in the three rivers and were higher than WHO recommended values of 10 µg L-1 for drinking water. Except for Periophthalmus sp. and Tympanotonus fuscatus from the Ankobra in which arsenic was not detected, concentrations in the organisms ranged from 0.2 to 2.8 mg kg-1. The maximum quantities of the organisms considered safe for consumption ranged from 375 to 5250 g per week. Caution however needs to be exercised as PTWI for arsenic needs revision, and some heavy metals such as mercury are more toxic than arsenic.

Filling the gap: Using fishers' knowledge to map the extent and intensity of fishing activity.

Knowledge of the extent and intensity of fishing activities is critical to inform management in relation to fishing impacts on marine conservation features. Such information can also provide insight into the potential socio-economic impacts of closures (or other restrictions) of fishing grounds that could occur through the future designation of Marine Conservation Zones (MCZs). We assessed the accuracy and validity of fishing effort data (spatial extent and relative effort) obtained from Fishers' Local Knowledge (LK) data compared to that derived from Vessel Monitoring System (VMS) data for a high-value shellfish fishery, the king scallop (Pecten maximus L.) dredge fishery in the English Channel. The spatial distribution of fishing effort from LK significantly correlated with VMS data and the correlation increased with increasing grid cell resolution. Using a larger grid cell size for data aggregation increases the estimation of the total area of seabed impacted by the fishery. In the absence of historical VMS data for vessels ≤15 m LOA (Length Overall), LK data for the inshore fleet provided important insights into the relative effort of the inshore (<6 NM from land) king scallop fishing fleet in the English Channel. The LK data provided a good representation of the spatial extent of inshore fishing activity, whereas representation of the offshore fishery was more precautionary in terms of defining total impact. Significantly, the data highlighted frequently fished areas of particular importance to the inshore fleet. In the absence of independent sources of geospatial information, the use of LK can inform the development of marine planning in relation to both sustainable fishing and conservation objectives, and has application in both developed and developing countries where VMS technology is not utilised in fisheries management.

Microplastics in the context of regulation of commercial shellfish aquaculture operations.

Shellfish aquaculture in the Salish Sea (encompassing the Strait of Juan de Fuca, Puget Sound, and the Georgia Strait) is a major source of clams, oysters, and mussels in the United States and Canada. Plastic gear is necessary for the viability of many of these operations. During the past few years, shellfish farm permits issued in Washington State have been challenged on various bases that have included allegations that the plastic gear is releasing microplastics, commonly defined as particles less than 5 mm in diameter. Published survey data on sources of marine plastic debris demonstrate the very limited contribution of aquaculture gear. Both permits and industry codes of practice provide procedures to minimize loss of gear to the marine environment. Plastic gear is also designed specifically to maintain its integrity and not degrade in the marine environment. Plastic degradation is greatest on beaches with high UV exposure, whereas aquaculture gear is mostly underwater and/or covered by biofoulants. Available data for microplastics in water, sediment, and biota of the Salish Sea do not suggest significant release of microplastics from shellfish aquaculture operations. Integr Environ Assess Manag 2017;13:522-527. © 2017 SETAC.

Effects of seawater temperature increase on economically relevant native and introduced clam species.

As a consequence of climate change, global warming is expected to increase during the 21st century. Taking this into account, the impact of rising temperatures on the native Ruditapes decussatus and introduced R. philippinarum bivalve species was assessed, through biochemical and mRNA transcription analyses. Our findings showed that at 21 °C the electron transport system and antioxidant enzyme activity, as well as the expression of Hsp70 gene were induced in R. decussatus when compared with 17 °C. On the other hand, at 25 °C results suggested that R. decussatus closed their valves during short periods, as a behavioral strategy, down-regulating the expression of genes associated with mitochondrial metabolism (Cox-1 and 16S) and chaperone function (Hsp70) compared with organisms at 17 °C. In addition, the introduced species (R. philippinarum) increased the electron transport system and antioxidant activities, as well as gene expression of antioxidant enzymes and molecular chaperone (Hsp70) at 21 °C. However, antioxidant mechanisms were not enough to prevent lipid membrane damages at 21 °C. At 25 °C R. philippinarum presented increased electron transport system and antioxidant activity, as well as the expression of genes associated with apoptosis regulation and molecular chaperone. Overall, the present findings indicate that in a global warming scenario both species are able to induce different mechanisms to mitigate the impacts of temperature increase.

Regional variation in bycatches associated with king scallop (Pecten maximus L.) dredge fisheries.

The biomass and composition of bycatch from king scallop dredge fisheries was assessed and compared between the English Channel, Cardigan Bay in Wales and around the Isle of Man. Bycatch composition varied significantly at localised, and broad, geographic scales. The mean proportion of scallop dredge bycatch biomass in the English Channel was 19% of total catch biomass. The proportion of bycatch was lower in Cardigan Bay (15%) but notably higher around the Isle of Man (53%). The proportion of individual bycatch species in dredge catches were low, therefore scallop dredging is unlikely to cause a substantial increase the population mortality of individual commercially fished species beyond that caused by the target fisheries for those species, or bycatches of other fisheries. The amount and mortality of organisms left on the seabed in the dredge path was not quantified in this study but should also be considered in management of the fishery. The discard rate of finfish and shellfish of commercial value from the king scallop dredge fishery in the English Channel was between 18 and 100%, with a higher rate of discarding occurring in the eastern English Channel compared to the west. The clear regional differences in bycatch composition and variation in the quantity of discards mean that an area by area approach to managing bycatch species is required in relation to the king scallop dredge fishery.

The hot oyster: levels of virulent Vibrio parahaemolyticus strains in individual oysters.

Vibrio parahaemolyticus is the leading cause of seafood-associated gastroenteritis and is most commonly transmitted by raw oysters. Consequently, detection of virulent strains of this organism in oysters is a primary concern for seafood safety. Vibrio parahaemolyticus levels were determined in 110 individual oysters harvested from two sampling sites in SC, USA. The majority of oysters (98%) contained low levels of presumptive V. parahaemolyticus However, two healthy oysters contained presumptive V. parahaemolyticus numbers that were unusually high. These two 'hot' oysters contained levels of presumptive V. parahaemolyticus within the gills that were ∼100-fold higher than the average for other oysters collected at the same date and location. Current V. parahaemolyticus detection practices require homogenizing a dozen oysters pooled together to determine V. parahaemolyticus numbers, a procedure that would dilute out V. parahaemolyticus in these 'hot' oysters. This study demonstrates the variability of V. parahaemolyticus densities taken from healthy, neighboring individual oysters in the environment. Additionally, environmental V parahaemolyticus isolates were screened for the virulence-related genes, tdh and trh, using improved polymerase chain reaction primers and protocols. We detected these genes, previously thought to be rare in environmental isolates, in approximately half of the oyster isolates.

Seafood-Associated Shellfish Allergy: A Comprehensive Review.

Shellfish are diverse, serve as main constituents of seafood, and are extensively consumed globally because of their nutritional values. Consequently, increase in reports of IgE-mediated seafood allergy is particularly food associated to shellfish. Seafood-associated shellfish consists of crustaceans (decapods, stomatopods, barnacles, and euphausiids) and molluskans (gastropods, bivalves, and cephalopods) and its products can start from mild local symptoms and lead to severe systemic anaphylactic reactions through ingestion, inhalation, or contact like most other food allergens. Globally, the most commonly causative shellfish are shrimps, crabs, lobsters, clams, oysters, and mussels. The prevalence of shellfish allergy is estimated to be 0.5-2.5% of the general population but higher in coastal Asian countries where shellfish constitute a large proportion of the diet. Diversity in allergens such as tropomyosin, arginine kinase, myosin light chain, and sarcoplasmic binding protein are from crustaceans whereas tropomyosin, paramyosin, troponin, actine, amylase, and hemoyanin are reported from molluskans shellfish. Tropomyosin is the major allergen and is responsible for cross-reactivity between shellfish and other invertebrates, within crustaceans, within molluskans, between crustaceans vs. molluskans as well as between shellfish and fish. Allergenicity diagnosis requires clinical history, in vivo skin prick testing, in vitro quantification of IgE, immunoCAP, and confirmation by oral challenge testing unless the reactions borne by it are life-threatening. This comprehensive review provides the update and new findings in the area of shellfish allergy including demographic, diversity of allergens, allergenicity, their cross-reactivity, and innovative molecular genetics approaches in diagnosing and managing this life-threatening as well as life-long disease.

Heavy metals in aquatic organisms of different trophic levels and their potential human health risk in Bohai Bay, China.

Fourteen aquatic organism samples were collected from Bohai Bay, and concentrations of five heavy metals were measured to evaluate the pollution levels in aquatic organisms and the potential risk to human health. The concentrations of Zn and Cu were much higher than those of Cd, Cr, and Pb in all the organisms. In general, the heavy metal concentration levels were in the order phytoplankton < zooplankton < fish < shrimp < shellfish. Heavy metal concentrations in higher trophic-level aquatic organisms in Bohai Bay were compared to those in the organisms from other worldwide coastal waters. The concentration levels of most heavy metals were higher than the 75th percentile, except that Pb concentration was between the 25th and 50th percentiles. The calculated bioconcentration factors (BCF) of Cr, Cu, and Pb for phytoplankton were less than 100, indicating no accumulation in primary producers. The bioaccumulation factor (BAF) of Pb for zooplankton was the highest, indicating significant Pb accumulation in zooplankton. For higher trophic-level aquatic organisms, the order of BAF values was fish < shrimp < shellfish for most metals except for Pb. The human health risk assessment suggests that strict abatement measures of heavy metals must be taken to decrease the health risk caused by consuming aquatic products.

Intertidal Concentrations of Microplastics and Their Influence on Ammonium Cycling as Related to the Shellfish Industry.

Microplastics are ubiquitous within the marine environment. The last 10 years have seen research directed at understanding the fate and effect of microplastics within the marine environment; however, no studies have yet addressed how concentrations of these particles could affect sedimentary processes such as nutrient cycling. Herein we first determine the concentration and spatial distribution of microplastics within Baynes Sound, a key shellfish-growing area within coastal British Columbia (BC). We also determined sediment grain size and % organic matter (OM) such that we could relate spatial patterns in sediment microplastic concentrations to sedimentary processes that determine zones of accretion and erosion. Using field-determined concentrations of microplastics, we applied laboratory microcosms studies, which manipulated sediment concentrations of microplastics, OM, and bivalves to determine the influence of sediment microplastics on ammonium cycling within intertidal sediments. Concentrations of microplastics determined within the intertidal sediment varied spatially and were similar to those found in other coastal regions of high urban use. Concentrations were independent of grain size and OM suggesting that physical processes other than those that govern natural sediment components determine the fate of microplastics within sediments. Under laboratory conditions, concentrations of ammonium were significantly greater in the overlying water of treatments with microplastics, clams, and OM compared with treatments without microplastics. These preliminary studies suggest that high concentrations of microplastics have the potential to alter key sedimentary processes such as ammonium flux. This could have serious implications, for example, contributing to eutrophication events in regions of the coast that are highly urbanized.

Spatial distribution and multiannual trends of potentially toxic microalgae in shellfish farms along the Sardinian coast (NW Mediterranean Sea).

In this study, the geographical distribution and multiannual trends of potentially toxic harmful algal species (HAS) were analysed at 18 mussel farms in Sardinia (Italy, North-Western Mediterranean Sea) using data derived from the Sardinian Regional Monitoring Programme (1988-2012). The results showed an increasing number of potentially toxic microalgae over the study period. Alexandrium catenella and Alexandrium minutum were the most harmful species detected. From 2002 to 2009, these species caused eight paralytic shellfish poisoning-positive events which temporarily stopped commercial trade of mussels. The statistical analysis indicated that some taxa exhibited temporal increasing trends in their abundance (e.g. Pseudo-nitzschia spp.), significant decrements (e.g. Dinophysis sp.), or both increasing and decreasing significant trends (e.g. A. minutum) at different sites, indicating the necessity of further in-depth studies, especially on certain taxa. Overall, the statistical elaboration of the long-term data provided useful signals for early detection of shellfish contamination by different potentially toxic HAS in defined sites. These signals can be used to develop best management practices.

Assessment of trace elements and legacy contaminant concentrations in California mussels (Mytilus spp.): relationship to land use and outfalls.

NOAA's Mussel Watch Program funded a regional pilot project in California that characterized contaminants associated with various land uses in conjunction with state, federal and private partners. Herein we assess the magnitude and distribution of trace elements and persistent organic contaminants in indigenous mussels with respect to land use, presence of outfalls and a subset of California Areas of Special Biological Significance (ASBS). We detected significant differences among the land use categories for the majority of trace elements and legacy contaminants measured. There was no significant difference between sites with and without outfalls. PCBs and PAHs were significantly lower in sites within ASBS boundary compared to other sites. The findings of this study will help fine tune future regional and national assessments as well as guide development of resource management and remediation activities and programs.