Ostrea Edulis Research Articles

The European native oyster,Ostrea edulis, in Wales, a historical account of a forgotten fishery

The history of the European native oyster has been documented for numerous countries within its natural range. However, the history ofOstrea edulisin Wales remains conspicuously absent from current UK and European peer-reviewed publications. It was therefore deemed necessary to address this and as a result in-depth research of archival data was conducted including local trade directories, decennial census returns, collections from the National Museum Wales, annual government fisheries reports and grey literature from local historical societies. These historical reviews resulted in the construction of a timeline which documents all the significant historical dates related toO. edulisin Wales from the early 1500 s to present day. Fisheries statistics for England and Wales were also analysed for the western regional oyster fisheries in an attempt to understand the contribution which the Welsh landings made to the region. The review revealed that the Welsh fishery was the primary contributor of regional landings from the early 1600 s with maximum landings reported 1894, with the oyster beds at Mumbles producing more oysters than any other port until the fishery closed in 1937. A commercial native oyster fishery no longer exists in Wales but there remains a small native oyster population in South Wales. It is hoped that the historical accounts of bountiful catches, overexploitation, and restoration ofO. edulisover the centuries in Wales may offer current conservation practitioners an insight into failures and mistakes of the past which could benefit the future of the European flat oyster in Wales.

Population dynamics of the European native oyster in a Marine Conservation Zone exposed to unregulated harvesting

The implementation of closed zones as fishery management tools have been shown to be successful in the augmentation of habitat restricted species. A concerted restoration effort is currently being focused on the European native oyster throughout its natural range. This has been accompanied by an increase in oyster prices. In 2018 a native oyster for restoration purposes cost 80 pence sterling by 2021 the price had increased to £3.50. It is likely that these price increases have led to harvesting pressure on established wild populations. A number of recovering Ostrea edulis assemblages in Strangford Lough Northern Ireland are located within a closed zone which has been in operation since 2008. This research investigated the effectiveness of this restricted area in regards to protecting O. edulis assemblages. The study revealed that within policed regions of the restricted area the population increased from an estimated 1000 oysters in 2004 to >88,000 in 2021. Furthermore, the age structure and population dynamics differed considerably from non-policed areas which still experienced harvesting. The research supports the use of closed zone legislation as a conservation tool with developing O. edulis populations. As newly restored populations become established, rising market prices will place these under increased harvesting pressure. The use of closed zones may offer a means of protecting these emergent populations.

Pronounced Mitochondrial DNA Population Genetic Structure in a Brooding Coastal Marine Invertebrate

Analyses of phylogeographic and population genetic structure of marine species with large population sizes, low fecundity, larval brooding, and limited dispersal such as the New Zealand flat oyster, Ostrea chilensis Küster, 1844, permit testing of the effects of historical and contemporary processes affecting patterns of coastal genetic differentiation and diversity. Analyses of DNA sequences from two mitochondrial DNA regions (COI, Cyt-b) compiled from O. chilensis individuals from 14 localities revealed a pronounced structure with three genetic clusters [Hauraki Gulf (HG); North; South] being resolved. These results suggest that historical processes have contributed to patterns of regional separation that have in turn contributed to regional genetic differences that are still observable today. Divergence time estimates of HG from North+South (1.97 Ma) and of North from South (0.36 Ma) indicate that O. chilensis from these regions represent evolutionarily significant units that evolved separately and rapidly in the early to middle Pleistocene. Analyses revealed no obvious periods of population expansion within any of the regions. These results contribute to a better understanding of how historical factors can result in pronounced mitochondrial DNA patterns of contemporary genetic structure and show how key life-history characteristics, e.g., larval brooding, can contribute to phylogeographic structure in coastal marine invertebrates.

Antimicrobial and Antioxidant Activities of Pleurotus Ostreatus as Edible Oyster Mushroom in Egypt.

Antimicrobial and Antioxidant Activities of Pleurotus Ostreatus as Edible Oyster Mushroom in Egypt.

Situated Knowing: Epistemic Perspectives on Performance

Situated Knowing: Epistemic Perspectives on Performance

Chromosome-level genome assembly of the European flat oyster (Ostrea edulis) provides insights into its evolution and adaptation

The European flat oyster (Ostrea edulis) is an endangered and economically important marine bivalve species that plays a critical role in the coastal ecosystem. Here, we report a high-quality chromosome-level genome assembly of O. edulis, generated using PacBio HiFi-CCS long reads and annotated with Nanopore full-length transcriptome. The O. edulis genome covers 946.06 Mb (scaffold N50 94.82 Mb) containing 34,495 protein-coding genes and a high proportion of repeat sequences (58.49 %). The reconstructed demographic histories show that O. edulis population might be shaped by breeding habit (embryo brooding) and historical climatic change. Comparative genomic analysis indicates that transposable elements may drive lineage-specific evolution in oysters. Notably, the O. edulis genome has a Hox gene cluster rearrangement that has never been reported in bivalves, making this species valuable for evolutionary studies of molluscan diversification. Moreover, genome expansion of O. edulis is probably central to its adaptation to filter-feeding and sessile lifestyles, as well as embryo brooding and pathogen resistance, in coastal ecosystems. This chromosome-level genome assembly provides new insights into the genome feature of oysters, and presents an important resource for genetic research, evolutionary studies, and biological conservation of O. edulis.

Book review. Biologija, ekologija I raznlikost jadranskih školjkaša, Melita Peharda Uljević, Rino Stanić and Pero Ugarković, Institut za oceanografiju i ribarstvo, Split, Croatia, 2022, 254 pp., with numerous color illustrations and drawings, and 98 color plates. ISBN 978-953-7914-08-0. Hardcover, in Croatian.

This book about the biology, ecology and biodiversity of Adriatic bivalves came as a really nice surprise and impressed me – notwithstanding I do not speak Croatian – for the excellent plates depicting 205 species of bivalves. But first things first and let’s start from the beginning. This volume is arranged around three main sections. The first covers general aspects of bivalve biology such as their morphology and anatomy, their taxonomic and ecological diversity, reproduction and age, fishing and aquaculture methods. The second delves deeper into the biology of the most exploited species (Arca noae, Glycymeris spp., Mytilus galloprovincialis, Lithophaga lithophaga, Pinna nobilis, Pecten jacobaeus, Spondylus gaederopus, Ostrea edulis, Venus verrucosa, Callista chione, Ruditapes spp., Polititapes spp. and Chamelea gallina) and is enriched by numerous beautiful color photographs and a list of references for each species (a remarkable review indeed!).

Epigenetic-associated phenotypic plasticity of the ocean acidification-acclimated edible oyster in the mariculture environment.

For marine invertebrates with a pelagic-benthic life cycle, larval exposure to ocean acidification (OA) can affect adult performance in response to another environmental stressor. This carry-over effect has the potential to alter phenotypic traits. However, the molecular mechanisms that mediate "OA"-triggered carry-over effects have not been explored despite such information being key to improving species fitness and management strategies for aquafarming. This study integrated the genome-wide DNA methylome and transcriptome to examine epigenetic modification-mediated carry-over OA impacts on phenotypic traits of the ecologically and commercially important oyster species Crassostrea hongkongensis under field conditions. Larvae of C. hongkongensis were exposed to control pH8.0 and low pH7.4 conditions, mimicking near future OA scenario in their habitat, before being outplanted as post-metamorphic juveniles at two mariculture field sites with contrasting environmental stressors for 9months. The larval carry-over OA effect was found to have persistent impacts on the growth and survival trade-off traits on the outplanted juveniles, although the beneficial or adverse effect depended on the environmental conditions at the outplanted sites. Site-specific plasticity was demonstrated with a diverse DNA methylation-associated gene expression profile, with signal transduction and the endocrine system being the most common and highly enriched functions. Highly methylated exons prevailed in the key genes related to general metabolic and endocytic responses and these genes are evolutionarily conserved in various marine invertebrates in response to OA. These results suggest that oysters with prior larval exposure history to OA had the ability to trigger rapid local adaptive responses via epigenetic modification to cope with multiple stressors in the field.

Dead men still tell tales: bivalve death assemblages record dynamics and consequences of recent biological invasions in Kingston Harbour, Jamaica

Abstract Short-lived biological invasions may leave lasting impacts on ecosystems well after they have concluded, yet the nature of such events is difficult to elucidate in the absence of monitoring efforts. Here, the ability for surficial death assemblages to recount such invasion events and their ecological legacies was tested using mangrove-dwelling bivalves from Kingston Harbour, Jamaica, where the Asian green mussel ( Perna viridis ) was introduced c. 20 years ago. While rare in Kingston Harbour today, relative densities of dead P. viridis shells mapped well to historical surveys from early into the invasion and thus help reconstruct spatial variations in invasion intensity. Live–dead discordance for the bivalve community further indicated that species have not returned to pre-invasion relative abundance distributions such that the economically-important mangrove oyster ( Crassostrea rhizophorae ) declined while the flat tree oyster ( Isognomon alatus ) rose to dominance. Finally, we report the presence of the charru mussel ( Mytella strigata ) in Kingston Harbour, a newly introduced species that has not yet been significantly incorporated into the subfossil record. This case study exemplifies the utility of underexploited sources of geohistorical data for informing the growing problem of human-assisted biological invasion.

Impact of COVID-19 on Croatian mariculture: Findings from the first national surveys

An overview of the negative effects of the COVID-19 pandemic on the mariculture industry of the republic of Croatia is provided. An initial online survey was circulated early after the onset of the pandemic and a follow-up field survey was performed a year into the pandemic. The surveyed companies varied in size (micro to medium enterprises), location (north, central and southern coast) and cultured organism (European flat oyster, Mediterranean mussel, European sea bass, Gilthead sea bream and/or Bluefin tuna) and were asked questions on the subject of economic and job losses, aquaculture supply chain processes and implemented or proposed measures for mitigation of negative effects. Results from the online survey showed higher economic loss than job loss, but companies reported increased job loss in the period leading to the field survey. Most companies reported reductions in sales and avenues of procurement, which, in addition to direct stressors, indirectly affected business processes. Micro enterprises fared well due to their part-time nature, low capital investments and running costs, while small to medium enterprises were under the most pressure. Large enterprises were barely affected as they had secure local and/or international distribution chains and dominated the market. Producers most affected were those that relied on the HoReCa market for product placement and/or had difficulty coping with existing stressors. Bivalve producers generally experienced a higher drop in sales than finfish farms and companies with specialized production were not able to adapt to market changes to the degree that more versatile businesses seemed capable of.

Chromosomal assembly of the flat oyster (Ostrea edulis L.) genome as a new genetic resource for aquaculture.

The European flat oyster (Ostrea edulis L.) is a native bivalve of the European coasts. Harvest of this species has declined during the last decades because of the appearance of two parasites that have led to the collapse of the stocks and the loss of the natural oyster beds. O.edulis has been the subject of numerous studies in population genetics and on the detection of the parasites Bonamia ostreae and Marteilia refringens. These studies investigated immune responses to these parasites at the molecular and cellular levels. Several genetic improvement programs have been initiated especially for parasite resistance. Within the framework of a European project (PERLE 2) that aims to produce genetic lines of O.edulis with hardiness traits (growth, survival, resistance) for the purpose of repopulating natural oyster beds in Brittany and reviving the culture of this species in the foreshore, obtaining a reference genome becomes essential as done recently in many bivalve species of aquaculture interest. Here, we present a chromosome-level genome assembly and annotation for the European flat oyster, generated by combining PacBio, Illumina, 10X linked, and Hi-C sequencing. The finished assembly is 887.2Mb with a scaffold-N50 of 97.1Mb scaffolded on the expected 10 pseudochromosomes. Annotation of the genome revealed the presence of 35,962 protein-coding genes. We analyzed in detail the transposable element (TE) diversity in the flat oyster genome, highlighted some specificities in tRNA and miRNA composition, and provided the first insight into the molecular response of O.edulis to M.refringens. This genome provides a reference for genomic studies on O.edulis to better understand its basic physiology and as a useful resource for genetic breeding in support of aquaculture and natural reef restoration.

Determination of Bioactive Compounds in Edible Mushroom Pleurotus eryngii

The current study designed to conduct with the main purpose to determine bioactive components of methanolic extract of edible oyster mushroom viz. Pleurotus eryngii using GC-MS technique. P. eryngii samples was purchased from local market, and subjected to methanolic extraction using Soxhlet extraction method. The results of GC-MS analysis delineated that the following prevailing bioactive compounds identified in the methanolic extract of P. eryngii i.e., conhydrin, diethyl phthalate, phthalic acid-butyl hex-3-yl ester (alkaloids), ar-turmerone (sesquiterpenoid), palmitic acid, myristic acid, phenol, and benzoic acid. In conclusion, polyphenols, alkaloids, terpenoids and Vitamin B class of secondary metabolites are the majorly identified in GC-MS analysis of methanolic extracts of P. eryngii. Therefore, methanolic extract of P. eryngii could be exploited for biopharmaceutical and therapeutic applications.

Risk Assessment of Heavy Metals Occurrence in Two Wild Edible Oyster Mushrooms (Pleurotus spp.) Collected from Rajaji National Park.

This study aimed at assessing the concentration of six heavy metals (Cd, Cr, Cu, Fe, Mn, and Zn) in two wild edible oyster mushrooms (Pleurotus ostreatus and Pleurotus djamor) collected from Rajaji National Park in Haridwar, India. For this purpose, mushroom samples were collected from selected locations (forest, residential, tourist, industrial areas, and transportation activities) from June 2021 to July 2022 and subsequently analyzed for selected heavy metals using atomic absorption spectroscopy (AAS). Results showed that both Pleurotus spp. had significantly varying (p < 0.05) concentrations of heavy metals. However, P. ostreatus showed relatively higher concentration levels of these metals compared to P. djamor. The mean concentrations (mg/kg dry weight) of the Cd, Cr, Cu, Fe, Mn, and Zn in P. ostreatus and P. djamor were 0.10 and 0.08, 0.87 and 0.64, 16.19 and 14.77, 28.49 and 27.15, 9.93 and 8.73, and 18.15 and 15.76, respectively. As indicated by the multivariate analysis tools i.e., principal component analysis (PCA) and hierarchical cluster analysis (HCA), the locations near the residential, industrial, and transportation activities had higher concentration levels of heavy metals. Moreover, the health risk studies using the target hazard quotient (THQ < 1) showed no significant health risk as the consumption of both Pleurotus spp., except for at one location, had high-traffic activities. The findings of this study provide vital information about the occurrence of potentially toxic heavy metals in wild edible Pleurotus spp. in Rajaji National Park in Haridwar, India representing a safeguard for mushroom consumers.

Reproductive Characteristics of the Flat Oyster Ostrea denselamellosa (Bivalvia, Ostreidae) Found on the Southern Coast of South Korea

In this study, we investigated the reproductive pattern of the commercially and ecologically important species, Ostrea denelamellosa, to inform stock management strategies in South Korea. Prior to the reproduction experiment, the complete mitochondrial (mt) genome of the flat oyster, Ostrea denselamellosa, was analyzed using next-generation sequencing technology. Then, to determine the reproductive pattern of Ostrea denselamellosa, we investigated monthly changes in the gametogenesis, reproductive cycle, and sex ratio from January to October 2021 in females. The total length of the mt genome sequence of O. denselamellosa was 16,225 bp and contained 37 genes (13 protein-coding genes, 22 tRNA genes, and 2 rRNA genes). Molecular phylogenetic comparison with 20 known species of Pteriomorphia showed that O. denselamellosa belongs to the family Ostreidae. In addition, O. denselamellosa clustered together with the O. denselamellosa Chinese strain, with a bootstrap value of 100%. Histological analysis indicated a discrepancy in gamete development of O. denselamellosa with synchronous maturation of oocytes and asynchronous development of spermatozoa in gonads. The spawning activity occurred between May and September with a temperature range gap of 6.5 °C. The spawning activity occurred from May when the temperature reached 16.7 °C until September when the temperature dropped below 23.2 °C. Furthermore, sex ratio bias was observed. This is the first study to report the complete mt genome sequence and examine the reproductive pattern in native O. denselamellosa in South Korea. Overall, these findings will help enhance the knowledge for the management and sustainable fishery of endangered oyster species including O. denselamellosa in the South Sea of Korea.

Are mussels and oysters capable of reducing the abundances of Picochlorum sp., responsible for a massive green algae bloom in Thau lagoon, France?

After an exceptional hydroclimatic year, a “massive green algae bloom”, dominated by the autotrophic picoeukaryote Picochlorum sp, was observed in 2018–2019 in the Thau lagoon. Oyster farmers informed decision-makers and scientists about an alarming halt to growth, loss of flesh weight and abnormal mortality in commercial size oysters, whereas mussel farmers observed no adverse effects. Two hypotheses were tested. First, Mediterranean mussels are capable of filtering Picochlorum spp. whereas Pacific and flat oysters are not. Second, picophytoplankton filtration rates vary with the size of the oyster, spats having greater ability than juveniles and commercial size oysters. A series of experiments was conducted in February 2019 using a series of beakers containing (i) three different types of solutions (1 L): water from the Thau lagoon containing Picochlorum at a rate of 45.2 million cells.L−1 (P) or diluted to 20.7 million cells. L−1 (D) and a solution of Isochrysis galbana containing 9.4 million cells. L−1; (ii) in the absence or presence of five types of bivalves: Pacific oysters of three different sizes (spat, juvenile and commercial size), flat oysters, and Mediterranean mussels of commercial size. Four separate water samples were taken during a 40-min incubation period to measure fluctuations in picophytoplankton and nanophytoplankton abundances using flow cytometry. Retention efficiency (%) was compared according to species and size. In contrast to Pacific and flat oysters, mussels with an average weight of 21.4 g, were able to drastically reduce the abundances of Picochlorum and depleted nearly one million Picochlorum cells per minute at 11.4 °C. These results suggest that the 1228 t of mussels that died in 2018 before the Picochlorum bloom could have helped limit the Picochlorum bloom if they had survived the heat and anoxia.

Crystallographic Texture of the Mineral Matter in the Bivalve Shells of Gryphaea dilatata Sowerby, 1816.

Simple SummaryA new for paleontology method has been applied to study the orientation distribution of the crystals that compose the fossils of mollusk shells. The method is based on the use of neutrons with high penetrating power and makes it possible to study bulk shells without destroying them. In this work, we studied how the habitat conditions and the process of fossilization influenced the distribution of shell crystallite orientations. It was possible to establish a relationship between the distribution of orientations and the shape of the shells.It is assumed that the crystallographic texture of minerals in the shells of recent and fossil mollusks is very stable. To check this, it is necessary to examine the shells of animals that had lain in sediments for millions of years and lived in different conditions. It is revealed that the crystallographic texture of calcite in the shells of Gryphaea dilatata from deposits from the Middle Callovian–Lower Oxfordian (Jurassic), which lived in different water areas, is not affected by habitat conditions and the fossilization process. The crystallographic texture was studied using pole figures measured by neutron diffraction. The neutron diffraction method makes it possible to study the crystallographic texture in large samples—up to 100 cm3 in volume without destroying them. The recrystallization features of the G. dilatata valve, which affect the crystallographic texture, were discovered for the first time. This is determined from the isolines appearance of pole figures. The crystallographic texture of the G. dilatata mollusks’ different valves vary depending on their shape. The pole figures of calcite in the thick-walled valves of G. dilatata, Pycnodonte mirabilis, and Ostrea edulis are close to axial and display weak crystallographic texture.

Chromosome-level reference genome for European flat oyster (Ostrea edulis L.).

The European flat oyster (Ostrea edulis L.) is a bivalve naturally distributed across Europe, which was an integral part of human diets for centuries, until anthropogenic activities and disease outbreaks severely reduced wild populations. Despite a growing interest in genetic applications to support population management and aquaculture, a reference genome for this species is lacking to date. Here, we report a chromosome-level assembly and annotation for the European Flat oyster genome, generated using Oxford Nanopore, Illumina, Dovetail OmniC™ proximity ligation and RNA sequencing. A contig assembly (N50: 2.38 Mb) was scaffolded into the expected karyotype of 10 pseudochromosomes. The final assembly is 935.13 Mb, with a scaffold-N50 of 95.56 Mb, with a predicted repeat landscape dominated by unclassified elements specific to O. edulis. The assembly was verified for accuracy and completeness using multiple approaches, including a novel linkage map built with ddRAD-Seq technology, comprising 4016 SNPs from four full-sib families (eight parents and 163 F1 offspring). Annotation of the genome integrating multitissue transcriptome data, comparative protein evidence and ab-initio gene prediction identified 35,699 protein-coding genes. Chromosome-level synteny was demonstrated against multiple high-quality bivalve genome assemblies, including an O. edulis genome generated independently for a French O. edulis individual. Comparative genomics was used to characterize gene family expansions during Ostrea evolution that potentially facilitated adaptation. This new reference genome for European flat oyster will enable high-resolution genomics in support of conservation and aquaculture initiatives, and improves our understanding of bivalve genome evolution.

First Data on Campylobacter spp. Presence in Shellfish in Croatia.

This study aimed to assess the presence of thermotolerant Campylobacter spp., as one of the most important foodborne zoonotic pathogens, in three shellfish species: mussels (Mytilus galloprovincialis), oysters (Ostrea edulis) and queen scallops (Aequipecten opercularis). The samples were collected from nine locations in the Istrian aquatory, Croatia. Isolation of Campylobacter was done according to standard ISO method, and species were identified using multiplex PCR. Isolates identified as C. jejuni and C. lari were genotyped using multilocus sequence typing (MLST) to determine the potential source of contamination. Among 108 examined samples of bivalve molluscs, mussels dominated and were the only ones found positive for the presence of Campylobacter (25.6%). In total, 19 C. lari and 1 C. jejuni strains were isolated. C. lari isolates found in this study belong to 13 sequence types (STs), and 9 of them are newly described in this paper. Two out of the four previously described C. lari STs that were found in this study were previously found in human stool. The only C. jejuni isolate was found to be sequence type 1268, which belongs to ST-1275 clonal complex that is almost exclusively found in seabirds and can sporadically cause infection in humans. Regarding the obtained results, introducing surveillance of thermotolerant Campylobacter in shellfish in the Republic of Croatia is advised as an improvement for public health safety.

Two parallel chromosome-level reference genomes to support restoration and aquaculture of European flat oyster Ostrea edulis.

This volume of Evolutionary Applications sees the publication of two genomes for the European native flat oyster Ostrea edulis, a species of significant evolutionary, ecological and commercial value. Each is a highly contiguous chromosome-level assembly from individuals of different genetic backgrounds, which have been benchmarked against one another. This situation has resulted from the serendipitous discovery that two independent research groups were both deep into the process of building, annotating and investigating separately produced assemblies. Due to constraints with funder requirements and the need to recognize early career researchers for their work, alongside the technical challenge of integrating assemblies from two very different genomes, there was limited capacity to merge the sequences into one publication at the stage of discovery. This issue is likely to become very common over the next few years until the technologies for working with multiple genomes at once, for example, graph genomes, become commonplace in nonmodel species. Consequently, both of our teams have decided to collaborate rather than compete, recognizing the benefit to copublishing two separate genome resources for the research community, each with distinct scientific investigations, and working collaboratively to benchmark the assemblies.

Genetic parallelism between European flat oyster populations at the edge of their natural range.

Although all marine ecosystems have experienced global-scale losses, oyster reefs have shown the greatest. Therefore, substantial efforts have been dedicated to restoration of such ecosystems during the last two decades. In Europe, several pilot projects for the restoration of the native European flat oyster, Ostrea edulis, recently begun and recommendations to preserve genetic diversity and to conduct monitoring protocols have been made. In particular, an initial step is to test for genetic differentiation against homogeneity among the oyster populations potentially involved in such programs. Therefore, we conducted a new sampling of wild populations at the European scale and a new genetic analysis with 203 markers to (1) confirm and study in more detail the pattern of genetic differentiation between Atlantic and Mediterranean populations, (2) identify potential translocations that could be due to aquaculture practices and (3) investigate the populations at the fringe of the geographical range, since they seemed related despite their geographic distance. Such information should be useful to enlighten the choice of the animals to be translocated or reproduced in hatcheries for further restocking. After the confirmation of the general geographical pattern of genetic structure and the identification of one potential case of aquaculture transfer at a large scale, we were able to detect genomic islands of differentiation mainly in the form of two groups of linked markers, which could indicate the presence of polymorphic chromosomal rearrangements. Furthermore, we observed a tendency for these two islands and the most differentiated loci to show a parallel pattern of differentiation, grouping the North Sea populations with the Eastern Mediterranean and Black Sea populations, against geography. We discussed the hypothesis that this genetic parallelism could be the sign of a shared evolutionary history of the two groups of populations despite them being at the border of the distribution nowadays.