Cultured Oyster Crassostrea Gigas Research Articles

Vertical transfer of microplastics in nearshore water by cultured filter-feeding oysters

Microplastics (MPs) are widely distributed in the sea, but the vertical transfer of MPs by marine organisms in coastal area is still poorly understood. In this study, we used laser direct infrared (LDIR) spectroscopy to determine the number and characteristics of MPs deposited by cultured oyster Crassostrea gigas and further compared the differences between MPs of natural deposit and biodeposit in field environments. The amounts of MPs found in the biodeposit of cultured oysters were 3.54 times greater than that in the natural deposition. The polymer types of biodeposit MPs also differed from those of natural deposition. It was estimated that a single oyster can deposit 15.88 MPs per day, which is a figure much higher than the initial results, and hotspots of MPs deposition may be formed within the oyster aquaculture area. We used generalized linear mixed model (GLMM) to further infer the sources of MPs in sediments and found that distance to shore, cultured zone and urban center were important predictors of MPs abundance in sediments of aquaculture area. The above results suggest that cultured bivalves have an important capacity for MPs biodeposition and will further change the vertical distribution pattern of MPs in coastal environments.

A Comparison of the Juvenile Dungeness Crab Metacarcinus magister Habitat Provided by Contemporary Oyster Aquaculture Versus Historical Native Oysters in a U.S. West Coast Estuary

Oysters and seagrasses provide structurally complex estuarine habitat for fish and invertebrate species. On the U.S. West Coast, complex oyster habitat was historically provided by the native Olympia oyster Ostrea lurida but is now provided by the commercially cultured oyster Crassostrea gigas. Ostrea lurida is found in subtidal and low intertidal areas, whereas C. gigas is predominantly cultured at higher intertidal elevations, resulting in a potential shift in available habitat for other fish and invertebrates that use this intertidal habitat. This change in the available habitat and its use was examined for the juvenile Dungeness crab Metacarcinus magister, and results showed the following: (1) comparable crab densities in remnant and restored populations of O. lurida and cultured C. gigas in two estuaries, (2) generally higher crab densities in both of these shell habitats than those observed in eelgrass Zostera marina or open mud habitat, (3) contemporary juvenile crab density in intertidal areas of Willapa Bay was most influenced by distance from the estuary mouth (declining with increasing distance) but also declined with increasing tidal elevation, and (4) when extrapolated to the estuarine ecosystem scale using areal estimates of habitat coverage, historical habitat provided by O. lurida potentially produced three times more juvenile crabs than those currently produced in cultured C. gigas. Nonetheless, both intertidal oyster habitats contribute more to juvenile crab production than eelgrass or open unstructured mud, and the ecosystem services associated with the placement of native and commercial oyster beds should be considered when defining goals for and permitting both aquaculture and native oyster restoration in Willapa Bay and other U.S. West Coast estuaries. Managers should consider this shifting temporal baseline in intertidal habitat provision, but also conducting similar evaluations at this broader estuary scale when evaluating habitat value for other resources that use these habitats differently.

Metal Concentrations in Oysters Crassostrea gigas Cultured in the Gulf of California and Risk Assessment to Human Health

The aim of this study was to evaluate the health risk of Cd, Cu, Pb, As, and Hg exposure through consumption of cultured oyster Crassostrea gigas from Sonoran coast. Metals were analyzed by atomic absorption spectrometry, and the risk assessment was estimated according to the hazard quotient (HQ), carcinogenic risk (CR), and hazard index (HI). The mean levels of Cd, Cu, Pb, As, and Hg in oysters were 1.35, 7.69, 0.29, 0.07, and 0.04 mg/kg wet weight, respectively. Results indicate that except for Cd, all mean levels were below than those recommended by the Mexican government, FAO, and European Union. The metal levels were similar to those reported on the Pacific Northwest Coasts. For risk assessment, the HQ, CR, and HI values did not exceed safety levels. Therefore, the oysters cultivated in the studied areas are safe for human consumption.

Chemical and Biological Properties on Sanitary of Cultured Oyster Crassostrea gigas Intended for Raw Consumption or Use in Seafood Products

Chemical and Biological Properties on Sanitary of Cultured Oyster Crassostrea gigas Intended for Raw Consumption or Use in Seafood Products

Vibrio sonorensis sp. nov. isolated from a cultured oyster Crassostrea gigas.

Strain CAIM 1076T was isolated from a cultured oyster Crassostrea gigas in Puerto Peñasco, Sonora state, México. The strain was taxonomically characterised by means of a genomic approach, comprising 16S rRNA gene sequence analysis, multilocus sequence analysis (MLSA), the DNA G+C content and whole genome analyses (ANI and GGDC), and by phenotypic characterisation. Strain CAIM 1076T was found to be catalase and oxidase positive, and cells were observed to be motile and facultative anaerobic. Analysis of the almost-complete 16S rRNA gene sequence placed this strain within the genus Vibrio; closely related species were Vibrio maritimus, Vibrio variabilis, Vibrio proteolyticus, and Vibrio nigripulchritudo with similarity values of 98.9, 98.5, 98.1, and 98.0%, respectively. MLSA of six housekeeping genes (ftsZ, gapA, gyrB, recA, rpoA and topA) was performed with the closely related species. A draft genome sequence of strain CAIM 1076T was obtained. The DNA G+C content of this strain was determined to be 44.5mol%. The genomic similarity values with V. maritimus were 71.6% (ANIb), 85.1% (ANIm) and a GGDC value of 20.3±2.3%; with V. variabilis the genomic similarities were 71.8% (ANIb), 85.4% (ANIm) and 20.0±2.3% (GGDC); with V. proteolyticus, 71.6% (ANIb), 84.1% (ANIm) and 18.8±2.2% (GGDC); and with V. nigripulchritudo, 70.8% (ANIb), 84.9% (ANIm) and 20.5±2.3% (GGDC). These ANI and GGDC values are below the thresholds for the delimitation of prokaryotic species, i.e., 95-96 and 70%, respectively. Phenotypic characters also showed differences with the closely related species analysed. The results presented here support the description of a novel species, for which the name Vibrio sonorensis sp. nov. is proposed, with strain CAIM 1076T (=CECT 9100T, =DSM 102190T) as the type strain.

Gamakamide C and D as Two New Analogues of Bitter-Tasting Cyclic Peptide with Hydantoin Structure from Oyster Crassostrea gigas

Two new bitter-tasting cyclic peptides comprising six amino acids, namely gamakamide C and D, were isolated from cultured oysters Crassostrea gigas. Dimethylaminoazobenzene sulfonyl-amino acid analysis detected Val and Leu in gamakamide C and Ile and Leu in gamakamide D. The molecular formula of gamakamide C was determined as by high-resolution fast atom bombardment mass spectroscopy (HR FAB-MS) (), and that of gamakamide D was determined as by HR FAB-MS (). Comparison of amino acid analyses and fragment ions by MS/MS among gamakamide C, D, and E (known), the structures of gamakamide C and D were confirmed and , respectively.

Vibrio crosai sp. nov., isolated from a cultured oyster Crassostrea gigas.

A motile, facultative anaerobic, marine bacterial isolate (CAIM 1437(T)) was obtained from a cultured oyster (Crassostrea gigas) in Sonora, México. The strain was studied by a phylogenetic analysis based on sequences of the 16S rRNA and five housekeeping genes, i.e. ftsZ, gapA, pyrH, recA, and topA. Comparison of the almost-complete 16S rRNA gene sequence with those of other type strains of the genus Vibrio showed a close relationship with the type strains of Vibrio orientalis and Vibrio rotiferianus, with similarity values ranging from 98.4 to 98.3 %, respectively. MLSA placed this strain within the Orientalis clade. The DNA-DNA hybridization value of strain CAIM 1437(T) with V. orientalis was 59 % and with V. rotiferianus 55 %. The DNA G+C content was determined to be 45.6 mol %. Phenotypic characteristics also showed differences with the species analysed. The results presented here support the description of a novel species, for which the name Vibrio crosai sp. nov. is proposed, with CAIM 1437(T) (= DSM 27145(T)) as the type strain.

Taxonomic Identity of a Tetrodotoxin-Accumulating Ribbon-wormCephalothrix simula(Nemertea: Palaeonemertea): A Species Artificially Introduced from the Pacific to Europe

We compared the anatomy of the holotype of the palaeonemertean Cephalothrix simula ( Iwata, 1952 ) with that of the holotypes of Cephalothrix hongkongiensis Sundberg, Gibson and Olsson, 2003 and Cephalothrix fasciculus ( Iwata, 1952 ), as well as additional specimens from Fukue (type locality of C. simula) and Hiroshima, Japan. While there was no major morphological discordance between these specimens, we found discrepancies between the actual morphology and some statements in the original description of C. simula with respect to supposedly species-specific characters. Our observation indicates that these three species cannot be discriminated by the anatomical characters so far used to distinguish congeners. For objectivity of scientific names, topogenetypes of the mitochondrial cytochrome c oxidase subunit I (COI) sequences are designated for C. simula, C. hongkongiensis, and C. fasciculus. Analysis of COI sequence showed that the Hiroshima population can be identified as C. simula, which has been found in previous studies from Trieste, Italy, and also from both the Mediterranean and Atlantic coasts of the Iberian Peninsula, indicating an artificial introduction via (1) ballast water, (2) ship-fouling communities, or (3) the commercially cultured oyster Crassostrea gigas ( Thunberg, 1793 ) brought from Japan to France in 1970s. Cephalothrix simula is known to be toxic, as it contains large amounts of tetrodotoxin (TTX). We report here that the grass puffer Takifugu niphobles ( Jordan and Snyder, 1901 )-also known to contain TTX- consumes C. simula. We suggest that the puffer may be able to accumulate TTX by eating C. simula.

Arsenic and Arsenic Species in Cultured Oyster (Crassostrea gigas and C. corteziensis) from Coastal Lagoons of the SE Gulf of California, Mexico

The aim of this study was to evaluate the bioavailability of arsenic (As) through cultured oyster Crassostrea gigas and Crassostrea corteziensis from four coastal lagoons (SE Gulf of California). Organisms were collected in two seasons (rainy and dry season), and they were analyzed for total arsenic and chemical speciation of this element. The concentrations of As in oyster soft tissue fluctuated between 5.44 and 9.56μg/g for rainy season and 6.46 and 8.33μg/g for dry season (dry weight) in C. gigas. In C. corteziensis, the As concentrations were <5μg/g for both seasons (dry weight). Arsenic speciation indicated arsenobetaine as the major arseno-compound accounting for 43.2-76.3% of total content of As. Lower contributions were obtained for non-extractable As (11.3-17.5%) and other molecules such as arsenocholine and methyl-arsonate (<5%). Inorganic arsenic was detectable in only two samples, at concentrations lower than <0.1μg/g. These As data are the first generated for these mollusks in NW Mexico and indicate that C. gigas and C. corteziensis farmed in this area are safe for human consumption in terms of arseno-compounds.

Polydorid species (Polychaeta: Spionidae) associated with commercially important mollusk shells in Korean waters

Polydorid species (Polychaeta: Spionidae) are widely known for their boring activities in mollusk shells and they often become harmful invaders. A total of seven species of the genera Polydora, Dipolydora, and Boccardiella were collected and described from wild and cultured mollusk shells from the intertidal to subtidal for the first time in Korean waters. The most common species observed to bore shells were Polydora haswelli and Polydora aura. Polydora haswelli is recorded for the first time in Asian waters. Wild and cultured abalone Haliotis discus discus, wild Atrina pectinata, and cultured oyster Crassostrea gigas were heavily infested by P. haswelli and P. aura. Polydora uncinata was very abundant only from the cultured oyster C. gigas from southeastern Korea, indicating that this species may have been transported with a different oyster population introduced to the area. Polydora limicola inhabited mud deposits in crevices of wild Chlamys farreri shells and caused severe damage to them. Small sized Dipolydora giardi and Dipolydora alborectalis were extracted only from wild shells. Boccardiella hamata was common associated with wild C. gigas in mud flats. We discuss the polydorid species from the viewpoint of aquaculture and unintentional transportation of alien species which have been introduced with commercially important host shells.

Gamakamide-E, a Strongly Bitter Tasting Cyclic Peptide with a Hydantoin Structure from Cultured Oysters Crassostrea gigas

A new cyclic peptide (six-membered amino acid), gamakamide-E (L-Leu-L-Met (SO)-L-Me-Phe-L-Leu-D-Lys-L-Phe), was isolated as a strongly bitter tasting compound from cultured oysters, Crassostrea gigas. The molecular formula of C 43 H 61 N 7 O 8 S was deduced from high resolution fast atom bom bardment mass spectrometry (HR FAB-MS) ([M + H] + m/z 836.4356 △= -2.4 mmu). Its unique structure including a hydantoin structure was firstly elucidated by nuclear magnetic resonance (NMR) analysis. Stereo chemistries of constituent amino acids were determined by chiral high performanced liquid chromatography analysis of natural and synthesized peptides.

Spatiotemporal variations in rocky intertidal malacofauna throughout Japan in the 1970s and 1980s

Spatial and temporal variations of benthic fauna over a wide region (>1,000 km) that includes complex ocean currents have seldom been quantitatively studied. The present study revealed malacofaunal variations on Japanese rocky shores affected by the Soya, Tsushima, Oyashio, and Kuroshio currents, and in the Inland Sea. On 29 shores in seven regions in these sea areas, previous researchers have recorded the number of molluscs in quadrats in spring and summer of 1978 and 1984–1986. Reanalyses of these records revealed the following patterns. (1) Shore-to-shore variation in malacofauna was correlated with shore-to-shore geographical distance less clearly for more southern regions. This might show that in southern regions many taxa with low relative abundance are haphazardly recorded on some shores and blur the effect of shore-to-shore distance on malacofaunal dissimilarity. (2) Region-to-region variation in malacofauna was significantly correlated with region-to-region geographical distance. This suggests the influences of environments and paleontological events specific to each current surrounding each region. (3) The pattern of dissimilarity between the Inland Sea and the other sea areas greatly changed from the 1970s to 1980s. This was due in part to the following density fluctuations on some shores in the Inland Sea: increases in the non-indigenous mussel Mytilus galloprovincialis, cultured oyster Crassostrea gigas, and littorinid Littorina brevicula reportedly abundant in sheltered areas; and decreases in the littorinid Nodilittorina radiata reportedly abundant in exposed areas and muricid gastropods Thais spp. showing imposex. This suggests an increase of anthropogenic perturbations during the study period in the Inland Sea which is surrounded by large cities and ports.

Reproduction, condition and mortality of the Pacific oysterCrassostrea gigas(Thunberg) in Sonora, México

Starting in 1997, mortality outbreaks in cultured oysters Crassostrea gigas have been reported in northwestern México. Previous studies have shown that massive die-offs result from multi-factor processes related to reproduction of the species. We studied the reproductive cycle and the condition index of cultured oysters in the coastal lagoon of El Soldado, Sonora, as well as the relationship of the life cycle with environmental parameters. We used oocyte diameter to determine reproductive stages and the condition index to describe the physiological state of oysters. Additionally, the temperature, salinity, seston and chlorophyll a were recorded at the study site. The results showed that C. gigas began accelerated reproductive activity in March under the influence of high temperature and increased concentrations of food. No spawning events were recorded and gametes were reabsorbed within the gonad in September and October. The results showed a period of nutrient storage during autumn–winter and another period of gamete production in spring–summer. A mortality event occurred at the end of winter, tied to significant increases in temperature and availability of food and in accelerated reproductive activity and high condition index. These conditions were very similar to those reported in other countries during summer die-offs of C. gigas.

Seasonal variations of free amino acids in oyster whole body and adductor muscle.

Seasonal variations in the level of free amino acids (FAA) and nonprotein nitrogen (NPN) were investigated in the whole body and adductor muscle of cultured oyster Crassostrea gigas. In the whole body, glutamic acid, alanine, glycine, proline, and β-alanine were abundant. There were marked seasonal variations in level of almost all FAA with a maximum in November to March and with a minimum around August, suggesting that the oyster meat is more palatable in winter to early spring than in summer. Taurine was also abundant in the whole body but showed maximum and minimum levels in June and September, respectively.In the adductor muscle, arginine was found to be rich in addition to the FAA present in the whole body. The FAA levels exhibited pronounced seasonal fluctuations with a maximum in November to April and with a minimum in either July or August. Taurine showed a trend similar to that of the whole body. NPN levels in both whole body and adductor muscle peaked in March and came to the bottom in July.