At the turn of the twentieth century, most of the world’s pearls were extracted from rich oyster and coral reefs on the northern Indian Ocean rim. This paper returns to the sites of extraction, studying imperial maps made from 1889–1925 to delineate oyster reefs on the seafloor. Building from the submarine up, I draw on environmental, animal, and history of science studies to explore the work of mapping oceanic, animate space. Attending to the role of divers, whose labor was required to make the seafloor visible, and the lifecycles of oysters, which changed over time, I argue that the seafloor represents a kind of unruly terrain, out of both the reach and control of imperial authorities. The paper’s final section meditates on reading humans as part of Indian Ocean landscapes and the possibilities this offers for further comparative, transnational work in a materialist vein.

This article explores the shoreline industries (oysters, salt, fish, lime) that emerged along the Laufaushan coast in Hong Kong's New Territories, in the period 1667 to 1978. The shoreline in question was controlled by a local security force, staffed by young men from a nearby lineage. The study draws on ethnographic research carried out by the author and local documents (of village and government origin) gathered on site.

Flood and drought events cause significant freshwater inflow fluctuations in estuaries, potentially leading to physiological stress and altered abundances of pathogens such as Vibrio vulnificus and Perkinsus marinus in oysters. To assess the effects of freshwater pulses to oyster reefs in subtropical estuaries in Texas, this study accomplished two goals: 1) reconstructed a reef-specific history of freshwater pulses through shell stable isotope analysis, 2) quantified the abundance of V. vulnificus and P. marinus through culture-dependent and culture-independent microbiology analyses. Oysters from a low-relief and high-relief reef experienced similar fluctuations in shell isotopes, indicating similar ranges of past environmental conditions. V. vulnificus and P. marinus were detected throughout the study but the abundance of these microorganisms was not correlated with environmental parameters or one another. Importantly, the P. marinus infection intensity was always lower at the high-relief reef, which suggests that high-relief reefs may experience lower infection frequencies.

Oyster aquaculture has experienced tremendous growth in the United States over the past decade, but little is known about consumer preferences for oysters. This study analyzed preferences for oysters with varied combinations of brands, production locations, and production methods (aquaculture vs. wild-caught) using dichotomous choice, revealed preference economic field experiments. Results suggest significant and distinct differences in behavior between first-time and regular oyster consumers. While infrequent oyster consumers were drawn to oysters labeled as wild-caught, experienced oyster consumers preferred oysters raised via aquaculture. These findings will be valuable for growers and policymakers who invest in aquaculture to improve surrounding ecosystems.

This is the first study of the metabolic enzyme activity and energy state of the dwarf oyster Ostrea stentina (Payraudeau, 1826) in Tunisia and in the Mediterranean region. The main purpose of this study was to examine the modulation of the physiological status of the oyster O. stentina depending on the season and the presence of parasite Marteilia refringens. The prevalence of bonamiosis and marteiliosis were established by PCR. Bonamia exitiosa was detected only in 2.91% of oysters while the prevalence of M. refringens was 100% (30 Ind./30) in February and 93.93% (28 Ind./30) in March. A 42–87% mortality rate was reported during the study period. Biochemical analyses were carried out to evaluate the management of the energy resources in regard to the biochemical changes of lipids and carbohydrates. The enzyme activity of pyruvate kinase (PK), citrate synthase (CS) and cytochrome c oxidase (CCO) were measured and the mean level of enzyme activity was respectively 20.31 mU mg−1 protein; 12.06 mU mg−1 protein and 3.59 mU mg−1 protein. Carbohydrate contents of O. stentina were very low all year round with an average of 15.18% in dry weight, and lipid contents remain similar (11.77% in dry weight) compared with the values reported for most other temperate bivalves. Enzyme activity significantly decreased over time (P < 0.001). The energy resources of the oyster O. stentina wherein much of the energy was devoted to reproduction seem to affect the defence system.

Consumers’ willingness to pay for postharvest-processed (PHP) raw oysters—oysters without health risks—is studied in experimental auction markets. The experimental design decomposes the effects of taste, objective risk information, and information on four PHP technologies on consumer valuations. Results show that relatively uninformed consumers are willing to pay equivalent amounts for PHP and traditional raw oysters. However, after a blind taste test, consumers are willing to pay a significant premium for traditional raw oysters, and the premium persists after objective information on risk and processing technologies is provided. The results are robust across PHP technologies.

Because of public health concerns, regulators are considering requiring post-harvest treatment of halfshell and shucked oysters by wholesalers and processors. Two recently developed post-harvest treatment technologies may actually reduce the costs of producing shucked oysters, but would increase the costs of halfshell oysters. An interregional model of the wholesale oyster industry is developed to estimate the effects of treatment requirements on prices, output, and employment. If post-harvest treatment is required for all Gulf oysters, price increases are estimated to be less than 20% and, in some cases, prices decrease. Results indicate producer and consumer losses in the halfshell market are partially or more than offset by gains in the shucked market.

Toxigenic strains of Vibrio cholerae serogroups O1 and O139 have caused cholera epidemics, but other serogroups – such as O75 or O141 – can also produce cholera toxin and cause severe watery diarrhoea similar to cholera. We describe 31 years of surveillance for toxigenic non-O1, non-O139 infections in the United States and map these infections to the state where the exposure probably originated. While serogroups O75 and O141 are closely related pathogens, they differ in how and where they infect people. Oysters were the main vehicle for O75 infection. The vehicles for O141 infection include oysters, clams, and freshwater in lakes and rivers. The patients infected with serogroup O75 who had food traceback information available ate raw oysters from Florida. Patients infected with O141 ate oysters from Florida and clams from New Jersey, and those who only reported being exposed to freshwater were exposed in Arizona, Michigan, Missouri, and Texas. Improving the safety of oysters, specifically, should help prevent future illnesses from these toxigenic strains and similar pathogenic Vibrio species. Post-harvest processing of raw oysters, such as individual quick freezing, heat-cool pasteurization, and high hydrostatic pressurization, should be considered.

An acute gastroenteritis (AGE) outbreak was reported in May 2013 in Gyeonggi Province, South Korea. Eight students who had eaten breakfast on 21 May 2013 at a high-school restaurant exhibited AGE symptoms. Our case-control study showed that a strong association was observed between AGE symptoms and fermented oyster consumption. Virological studies also indicated that noroviruses (NoVs) were detected from both clinical samples and fermented oyster samples, and multiple different genotypes (genogroups GII.4, GII.11 and GII.14) of NoVs were present in both samples. The nucleotide sequence similarity between the strains found in the clinical samples and those in the fermented oysters was more than 99·5%. Therefore, to prevent further outbreaks, proper management of raw oysters is necessary and the food industry should be aware of the risk of viral gastroenteritis posed by fermented oysters contaminated with NoVs.

The Mediterranean Sea is currently under siege by a conspicuous alien pressure, and, within some families (e.g. the Ostreidae), the number of native species seems to be remarkably outnumbered by that of the alien ones. We wanted to test the reliability of the molecular data currently available on the small alien oysters recently invading the Mediterranean Sea. Samples from Greece and Turkey, encompassing the known species-specific morphological variation, were sequenced for the markers with the widest taxonomic coverage in the group of small oysters (i.e. the 16S rDNA and the COI). The sequences obtained have been compared with those available in GenBank, and a possible identification at the species level has been finally tested in a DNA-barcoding fashion. The present results clearly demonstrated that our samples belong to a single, morphologically highly variable species. Their 16S sequences were closely related to a sequence registered under the name Dendostrea folium, with a genetic distance which does not warrant conspecificity. Additionally, a remarkable number of sequences retrieved from the GenBank (of both genes) did not form a monophyletic group according to the published classification of the vouchers, suggesting—at least in part—an origin from specimens not properly identified. Both genes seem promising for use as DNA-barcode, although the COI will probably prove more effective. Therefore, we urge the availability of a baseline of oyster pedigreed DNA barcode sequences in the public databases, to allow the use of such genetic data to reliably monitor bio-invasions in the Mediterranean Sea.

We investigated norovirus (NoV) concentrations and genotypes in oyster and faecal samples associated with two separate oyster-related outbreaks of gastroenteritis in Ireland. Quantitative analysis was performed using real-time quantitative reverse transcription polymerase chain reaction and phylogenetic analysis was conducted to establish the NoV genotypes present. For both outbreaks, the NoV concentration in oysters was >1000 genome copies/g digestive tissue and multiple genotypes were identified. In faecal samples, GII.13 was the only genotype detected for outbreak 1, whereas multiple genotypes were detected in outbreak 2 following the application of cloning procedures. While various genotypes were identified in oyster samples, not all were successful in causing infection in consumers. In outbreak 2 NoV GII.1 was identified in all four faecal samples analysed and NoV GII concentrations in faecal samples were >108 copies/g. This study demonstrates that a range of NoV genotypes can be present in highly contaminated oysters responsible for gastroenteritis outbreaks.

An outbreak of gastroenteritis affected at least 240 persons who had eaten at a gourmet restaurant over a period of 7 weeks in 2009 in England. Epidemiological, microbiological, and environmental studies were conducted. The case-control study demonstrated increased risk of illness in those who ate from a special ‘tasting menu’ and in particular an oyster, passion fruit jelly and lavender dish (odds ratio 7·0, 95% confidence interval 1·1–45·2). Ten diners and six staff members had laboratory-confirmed norovirus infection. Diners were infected with multiple norovirus strains belonging to genogroups I and II, a pattern characteristic of molluscan shellfish-associated outbreaks. The ongoing risk from dining at the restaurant may have been due to persistent contamination of the oyster supply alone or in combination with further spread via infected food handlers or the restaurant environment. Delayed notification of the outbreak to public health authorities may have contributed to outbreak size and duration.

We studied the prevalence and intensity of the parasitic copepod Myicola ostreae in 2 closely related oysters Crassostrea angulata and C. gigas and their F1 hybrids. The effects on host and host reaction were also analysed to better understand host-parasite relationships between copepods and bivalve molluscs. Full reciprocal crosses were carried out between C. angulata and C. gigas and the progenies were reared in the wild in Ria Formosa Lagoon (Portugal), allowing natural infestation by M. ostreae. Prevalence and intensity were significantly higher in C. angulata than in C. gigas. The parasite level of F1 hybrids was similar to C. angulata and significantly higher than in C. gigas. The results of our study support a hypothesis of dominantly inherited susceptibility to M. ostreae infestation. Moreover, copepods were observed on the gill surface of C. gigas engulfed by a capsule-like structure. Histological analyses revealed that the copepods were surrounded by a massive agglomerate of haemocyte-like cells encircled by a thin layer of fibroblast-like cells. This encapsulation response was not observed in C. angulata or in F1 hybrids. These results suggest that the differential susceptibility to M. ostreae between C. angulata and C. gigas may be ascribed to host defence factors.

Adult oysters Crassostrea gigas were experimentally fed with Alexandrium catenella and Alexandrium minutum which are responsible for recurrent toxic blooms in French coastal waters. C. gigas produced faeces and pseudofaeces containing intact and viable temporary pellicular cysts of these two Paralytic toxin producing species. When incubated in favourable conditions, these pellicular cysts were able to germinate at high rates (between 74 and 94%) and the resulting vegetative cells divided with growth rates close to the non- ingested cells (control). The toxin profile of the vegetative cells originated from the germinated temporary cysts was analyzed by liquid chromatography/fluorescence detection. Total toxin content of newly germinated cells was lower than that of cultured cells. Besides, cell contents of C2, B1, B2 and dcGTX3 toxins featured some changes. Our results suggest that the increased spreading of toxic dinoflagellates through the transfer of shellfish from contaminated towards pristine coastal areas cannot be ruled out. We also suggest that pellicular cysts and newly germinated cells could represent a potential way for the transfer of paralytic toxins toward the higher trophic levels.

The European, native or flat oyster, Ostrea edulis, has been the subject of human-mediated translocation and aquaculture in Europe for centuries and may have diluted or masked natural population genetic structure. Samples of O. edulis from 10 sites in Scotland and The Netherlands, Brittany and Norway were collected and genotyped at up to six microsatellite loci. Numbers of alleles and heterozygosity per locus were high in all populations and were consistent with previous microsatellite studies. There is no evidence that extensive traditional oyster aquaculture has led to loss of allelelic diversity. Deficiencies of heterozygotes against Hardy-Weinberg predictions were common and were probably mainly due to the presence of null alleles. Overall, population differentiation (F st = 0.05) was estimated to be higher than previous studies and could be resolved into four main genetic groups (1) Norway, (2) The Netherlands and Brittany, (3) Scotland apart from (4) Skye. The genetic distinctness of Norway oysters agrees with previous findings. The distinctiveness of the Skye population could be partly due to an artefact of small sample sizes and partly due to the founder effect of importation of Brittany oysters in the 1950s. Further studies are required to ascertain whether the Skye population may be deserving of special conservation status. The results suggest that human aquaculture activities over recent centuries have probably diluted any original local genetic differentiation within Scotland, but that potentially important genetic differentiation still exists at the wider scale across Europe