Ostrea Edulis Research Articles

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.

A single genomic region involving a putative chromosome rearrangement in flat oyster (Ostrea edulis) is associated with differential host resilience to the parasite Bonamia ostreae.

European flat oyster (Ostrea edulis) is an ecologically and economically important marine bivalve, that has been severely affected by the intracellular parasite Bonamia ostreae. In this study, a flat oyster SNP array (~14,000 SNPs) was used to validate previously reported outlier loci for divergent selection associated with B. ostreae exposure in the Northeast Atlantic Area. A total of 134 wild and hatchery individuals from the North Sea, collected in naïve (NV) and long‐term affected (LTA) areas, were analysed. Genetic diversity and differentiation were related to the sampling origin (wild vs. hatchery) when using neutral markers, and to bonamiosis status (NV vs. LTA) when using outlier loci for divergent selection. Two genetic clusters appeared intermingled in all sampling locations when using outlier loci, and their frequency was associated with their bonamiosis status. When both clusters were compared, outlier data sets showed high genetic divergence (F ST > 0.25) unlike neutral loci (F ST not ≠ 0). Moreover, the cluster associated with LTA samples showed much higher genetic diversity and significant heterozygote excess with outlier loci, but not with neutral data. Most outliers mapped on chromosome 8 (OE‐C8) of the flat oyster genome, supporting a main genomic region underlying resilience to bonamiosis. Furthermore, differentially expressed genes previously reported between NV and LTA strains showed higher mapping density on OE‐C8. A range of relevant immune functions were specifically enriched among genes annotated on OE‐C8, providing hypotheses for resilience mechanisms to an intracellular parasite. The results suggest that marker‐assisted selection could be applied to breed resilient strains of O. edulis to bonamiosis, if lower parasite load and/or higher viability of the LTA genetic cluster following B. ostreae infection is demonstrated.

Genome-Wide Association and Genomic Prediction of Growth Traits in the European Flat Oyster (Ostrea edulis).

The European flat oyster (Ostrea edulis) is a bivalve mollusc that was once widely distributed across Europe and represented an important food resource for humans for centuries. Populations of O. edulis experienced a severe decline across their biogeographic range mainly due to overexploitation and disease outbreaks. To restore the economic and ecological benefits of European flat oyster populations, extensive protection and restoration efforts are in place within Europe. In line with the increasing interest in supporting restoration and oyster farming through the breeding of stocks with enhanced performance, the present study aimed to evaluate the potential of genomic selection for improving growth traits in a European flat oyster population obtained from successive mass-spawning events. Four growth-related traits were evaluated: total weight (TW), shell height (SH), shell width (SW) and shell length (SL). The heritability of the growth traits was in the low-moderate range, with estimates of 0.45, 0.37, 0.22, and 0.32 for TW, SH, SW and SL, respectively. A genome-wide association analysis revealed a largely polygenic architecture for the four growth traits, with two distinct QTLs detected on chromosome 4. To investigate whether genomic selection can be implemented in flat oyster breeding at a reduced cost, the utility of low-density SNP panels was assessed. Genomic prediction accuracies using the full density panel were high (> 0.83 for all traits). The evaluation of the effect of reducing the number of markers used to predict genomic breeding values revealed that similar selection accuracies could be achieved for all traits with 2K SNPs as for a full panel containing 4,577 SNPs. Only slight reductions in accuracies were observed at the lowest SNP density tested (i.e., 100 SNPs), likely due to a high relatedness between individuals being included in the training and validation sets during cross-validation. Overall, our results suggest that the genetic improvement of growth traits in oysters is feasible. Nevertheless, and although low-density SNP panels appear as a promising strategy for applying GS at a reduced cost, additional populations with different degrees of genetic relatedness should be assessed to derive estimates of prediction accuracies to be expected in practical breeding programmes.

De Novo Transcriptome Assembly and Analysis of the Flat Oyster Pathogenic Protozoa Bonamia Ostreae.

The flat oyster Ostrea edulis is an oyster species native to Europe. It has declined to functional extinction in many areas of the NE Atlantic for several decades. Factors explaining this decline include over-exploitation of natural populations and diseases like bonamiosis, regulated across both the EU and the wider world and caused by the intracellular protozoan parasite Bonamia ostreae. To date, very limited sequence data are available for this Haplosporidian species. We present here the first transcriptome of B. ostreae. As this protozoan is not yet culturable, it remains extremely challenging to obtain high-quality -omic data. Thanks to a specific parasite isolation protocol and a dedicated bioinformatic pipeline, we were able to obtain a high-quality transcriptome for an intracellular marine micro-eukaryote, which will be very helpful to better understand its biology and to consider the development of new relevant diagnostic tools.

A Review of the Ecosystem Services Provided by the Native Oyster (Ostrea edulis): Implications for Restoration

Native oyster (Ostrea edulis) habitat has been decimated across the majority of its natural range as a result of human activity. In recent decades, oyster restoration projects have gathered increasing support due to their potential to provide ecosystem services that offset increasing pressure from human development, resource demand, and also climate change. These ecosystem services are reviewed here, so as to inform the potential benefit of restoration projects. Ecosystem services can be divided into four categories: provisioning services through direct utilisation of oysters and the species they support, regulating services that help maintain a healthy environment, habitat services that benefit biodiversity, and cultural services that can influence tourism and wider cultural values. Ecosystem services are often interlinked in complex networks, though these can be linked back to two overarching ecosystem functions, stemming from either the filter feeding activity of oysters, or the physical reef structure that they provide. The MARINEFF oyster enhancement reefs installed in the Solent, September 2020, are intended to support the extensive Solent Oyster Restoration Project initiated by the Blue Marine Foundation. The expectation is that they will facilitate both oyster settlement and the release of larvae for the repopulation of the Solent system. This may contribute to the recovery of ecosystem services mentioned in this review. It is important to note however that there is a lack of baseline data for native oysters, and the ecosystem service values they provide are poorly constrained, meaning that ecosystem service estimates are derived largely from other species of oyster. This inhibits our ability to accurately calculate and model natural capital provided by native oysters, highlighting the necessity for further research so as to inform management and restoration targets.

Identifying knowledge gaps for successful restorative aquaculture of Ostrea edulis: a bibliometric analysis.

Background:Active restoration is necessary to enhance the recovery ofOstrea edulisreefs, which contribute to many ecosystem services. Restoration can be integrated within aquaculture practices, bringing positive environmental changes while maximising space utilisation. The restoration project MAREA (MAtchmaking Restoration Ecology and Aquaculture) aims to bring back O. edulisin the North-West Adriatic addressing the feasibility of its cultivation. Both successful restoration and sustainable aquaculture require a thorough understanding of the ecological needs, as the requirements of both activities need to be harmonized. Therefore, one of the preliminary activities before embarking on the pilot was the completion of a thorough literature review to identify research directions and gaps required for 'restorative aquaculture', aiming to gather the most up to dateO . edulisknowledge on a global and local scale. Methods:Internet (Web of Science, Scopus, Google scholar) and physical resources (libraries) were searched for all available global and local knowledge onO . edulis. Bibliometrixwas used to identify the main research topics using keywords, titles, and abstracts analyses. Studies were then manually screened and summarised to extract knowledge specific to restoration and aquaculture. Results:While restoration studies are recent, evidence for the loss of this species and potential causes (and solutions) have been discussed since the end of the 19 thcentury. While diseases were a leading cause for reef loss, substratum limitation appears to be one of the leading limiting factors for both restoration and aquaculture ofO . edulis, and was already mentioned in the early texts that were found. Conclusions:The review highlighted that restoration success and aquaculture feasibility depend upon the crucial stage of settlement. The project 'MAREA' will therefore increase its focus on this stage, both in terms of timing, location, and materials for settlement plates placement.

Prevalence of Protozoan Parasites Cryptosporidium sp. and Callimastix equi in the Edible Oyster Saccostrea cucullata and Its Relationship with Selected Water Quality Parameters in Sundarbans Region of West Bengal, India.

Prevalence of protozoan parasites Cryptosporidium sp. and Callimastix equi in the edible oyster resources Saccostrea cucullata, and its relationship with selected water quality parameters such as temperature, pH and salinity in Sundarbans region of West Bengal, India, have been assessed and discussed elaborately. Edible oysters S. cucullata were collected randomly from the selected study site Frasergunj of Sundarbans region and protozoan parasites such as Cryptosporidium sp. and C. equi were isolated, stained and determined its prevalence. Relationship of water temperature, pH and salinity with the prevalence of protozoan parasite had been assessed and analyzed. Prevalence of infection of Cryptosporidium sp. is much more than the C. equi found in S. cucullata. The infections of the parasites are higher during monsoon then pre-monsoon season. Significant negative correlation (P < 0.05) occurs between pH of water and prevalence of Cryptosporidium sp. and C. equi in the edible oyster S. cucullata collected from Frasergunj of Sundarbans region, South 24 Parganas of West Bengal. The C. equi parasite follows a seasonal pattern of infection varying significantly with salinity (P < 0.01) of the water in the edible oyster, S. cucullata collected from Frasergunj of South 24 Parganas of West Bengal. These results indicate that the Cryptosporidium sp. and C. equi contamination is accompanying with public health risks if edible oysters are consumed uncooked of undercooked. Extremes and/or rapid fluctuations of important environmental factors such as water temperature, salinity, pH can seriously compromise oyster health and outcome of aquaculture.

Evolution of agricultural wastes for the cultivation of edible mushroom Pleurotus eryngii

This research studies the possible use of some of Iraq's local agricultural wastes as growth substrates for producing the edible oyster mushroom (Pleurotus eryngii). The biological process of growing and producing edible mushrooms is a bioconversion of organic wastes to bioprotein (mycoprotein). Therefore, this study aims to investigate nine different substrates from plant residues. The three primary substrates are typical viz date palm waste (Phoenix dactylifera), maize cob (Zea mays) and cane (Phragmites communis), with two types of additional enrichment, i.e., rice husks (Oryza sativa) and corn seeds husks (Zea mays), and without further enrichment (control). The experiment was randomly distributed according to Randomized Complete Design (RCD), with three replicates. The less crop cycle period (day) which in Treatments T7 and T8 (30.33, 31.67 days) when T2 (100%Corncobs), T1 (100%Waste of Date palm), T7 (80%Waste of the date palm with 20%Corn husks) and T8 (80% Corncobs with 20%Corn husks) provide the crest mushrooms yield arrived 293.0 280.7, 268.7 and 264.0 g kg-1 substrate respectively. Keywords. Bio protein; lignocelluloses; Mushroom substrates; Oyster mushrooms

Holocene development of Brabrand Fjord, eastern Jylland, Denmark.

The Brabrand Sø area west of Aarhus in eastern Jylland, Denmark, was deglaciated about 18 000 to 17 000 years ago. Coring in the present-day lake area revealed Early Holocene stream deposits overlain by marine deposits. The area was transgressed by the sea at c. 8500 cal. years BP and a 12 km long, narrow fjord was formed. In the beginning, the fjord housed a species-poor marine or brackish-water fauna with molluscs Hydrobia sp. (mudsnail), Littorina littorea (winkle), Mytilus edulis (blue mussel) and Cerastoderma sp. (cockle). This phase was followed by a phase during which the fjord housed a species-rich fauna that included Ostrea edulis (European flat oyster) and Ruditapes decussatus (palourde clam). During this phase the salinity and summer water temperatures were higher than in present day Aarhus Bugt and we also see evidence for strong bottom currents. This phase was probably characterised by a fairly large tidal amplitude. Two radiocarbon ages of O. edulis shells of c. 6250 and 6700 cal. years BP indicate that such conditions peaked during the period of the Ertebølle culture. The high-salinity phase was followed by a phase with a more species-poor fauna, this phase was also characterised by a high sedimentation rate – a feature seen in other fjords in the region. We suggest that the shift could be due to a decrease in tidal amplitude. Brabrand Fjord was eventually transformed into a lake due to land uplift and closure of the connection to Aarhus Bugt due to longshore sediment transport but the timing of the transition from fjord to lake is still unknown.

Oyster larvae swim along gradients of sound

Abstract Marine soundscapes provide navigational information for dispersing organisms, but with wide‐scale habitat loss, these soundscapes are becoming muted. Consequently, dispersing larvae that use soundscapes for navigation may be lost at sea, limiting the success of restoration efforts that rely upon the recruitment of dispersing organisms to restore habitat. Where limited larval supply constrains restoration efforts, using speakers to create gradients in healthy soundscapes could provide the navigational cue that attract larvae and enhances recruitment. Combining laboratory and field studies, we test whether broadcasting soundscapes might act as a directional cue for oysters targeted for national‐scale reef restoration; the Australian flat oyster Ostrea angasi. In the laboratory, we tested whether settlement of larvae increases along a gradient of increasing sound intensity (8 m laboratory tank) versus a no sound control, and whether settlement increases with soundscapes that approximate healthy reefs. In the field, we tested the context dependency and magnitude of using boosted soundscapes for restoration practice in areas of low, medium and high background noise, by observing the settlement rates of naturally recruiting oysters at three restoration sites when exposed to boosted reef sound relative to ambient conditions. In the laboratory, we showed that 83% of larvae swim horizontally towards reef sound to settle in greater densities closer to its source, a near doubling of the larvae (44%) that dispersed in the no sound controls. Larval settlement increased by 300% in the presence of reef sound relative to controls in the laboratory. In the field, speakers increased larval settlement in localities of lower background noise. To our knowledge, this is the first evidence that oyster larvae can swim horizontally and choose to move towards a sound source. Synthesis and applications. We discovered that oyster larvae can swim horizontally towards reef sound and then settle in higher densities, relative to controls. Importantly, this effect of sound on recruitment is enhanced in localities of lower background noise. We propose that where recruitment is limited, restoration practitioners best use acoustic technology in localities of lower background noise to guide larvae to boost recovery.

Recent change in spatial distribution of the European flat oyster (Ostrea edulis) inferred from field data and empirical models of living oysters and empty shells.

Marine coastal areas are increasingly affected by human activities resulting in changes in species and habitat distributions. Understanding these patterns and its causes and consequences is important for conservation and restoration of such changing habitats. One habitat that has been heavily affected by human use are the North Sea oyster beds which once were abundant but have lost large parts of its coastal distribution due to overexploitation. Based on data of living and dead assemblages of Ostrea edulis collected using video transects, we used an ensemble modeling technique to model and predict current and recent distribution of O. edulis along the Swedish west coast where its distribution is, in relative terms, still rather unaffected. We could detect a recent change in the distribution of O. edulis along the coast which to a large extent could be attributed to a change in depth distribution, suggesting that the population of O. edulis have a slightly shallower distribution today than in the past. Although a potential mismatch between living and dead assemblages, caused by a complex combination of biological and environmental conditions, needs to be considered in the interpretations drawn, it may be a way around the lack of suitable background data in management decisions. This provides important information for management and conservation of the native oyster beds. Furthermore, this study illustrates a method for identifying recent changes in species distribution using dead assemblages of bivalves.

Feeding response and dynamic of intoxication and detoxification in two populations of the flat oyster Ostrea chilensis exposed to paralytic shellfish toxins (PST)

Juvenile oysters (Ostrea chilensis) from two populations (Quempillén estuary and Pullinque bay) were exposed to a toxic diet containing paralytic shellfish toxins (PST), produced by Alexandrium catenella, followed by a detoxification period. Feeding behaviour, toxin profile, dynamics of intoxication/detoxification, and survival were evaluated over the entire experimental period. Both populations reduced their feeding rates during the 30-day exposure to the toxic diet. This negative effect was reversible when the diet was switched to the non-toxic one. Oysters from the estuary accumulated PST more rapidly than the population from the bay, suggesting their increased ability to cope with more adverse conditions. Both populations showed low detoxification capacity. Survival was significantly higher in oysters from the estuary, compared to those from the bay. Due to the increasing frequency and intensity of A. catenella blooms in southern Chile, it is necessary to better understand the responses of O. chilensis in different environments. This is important not only because of the ecological and commercial relevance of the bivalve, but also in consideration of expected climate change scenarios, where the new environmental conditions could favour the frequency and intensity of harmful algal bloom events.

The state of the European oyster population in Tsemesskaya bay

Ostrea edulis (Linnaeus, 1758) is listed in the Red Book. There are many assumptions about her disappearance. The European oyster is found in marine fouling of reinforced concrete piers. Oysters on stilts were located from the water's edge and a meter deep, there were practically no lower ones. Depth 2.5 – 3.5 m . Ostrea edulis L. is endangered, so it is necessary to conduct additional research on the diseases of these mollusks to establish the causes of degradation of natural populations of the European. It is necessary to take measures to restore the population of the European oyster, such as breeding oysters that are not susceptible to diseases.

STUDY OF AROMATIC COMPONENTS IN THE COURSE OF INITIATING ENZYMATIC REACTIONS IN THE EDIBLE MUSHROOM PLEUROTUS OSTREATUS

Various branches of the food and medical industries widely use mushrooms, that is why their aromatic characteristics are quite important. This paper presents a comparative analysis of the aromatic and fatty acid composition of the mycelium of the edible oyster mushroom (Pleurotus ostreatus (Jacq.) P. Kumm., strain K-17) cultured on a glucose-peptone-yeast growth medium with wheat bran added. The quantitative and qualitative composition of the aromas has shown that wheat bran components affect the aroma-forming reactions during the growth of the mycelium of P. ostreatus. It has been established that the introduction of wheat bran increases the content of 1-octen-3-ol, the main fungal aromatic component. In the culture liquid, 1-octen-3-ol increases by 1.4 times, as compared with classic samples cultured on a growth medium without wheat bran. Also, in the mycelium cultured on a wheat bran-containing growth medium, the total quantity of identified aromatic components increases by 1.7 times. In this mycelium, the two main components of the mushroom’s aroma are formed: 1-octen-3-ol and hexanal. In other samples, these important components are absent. The results of this study confirm that the formation of the two main fungal aromatic components, 1‑octen-3-ol and hexanal, involves polyunsaturated fatty acids, namely linoleic acid. Its content decreased in parallel with the accumulation of aromatic components throughout culturing in the wheat bran-containing medium. The data obtained allow establishing how initiation of enzymatic oxidative reactions changes the aroma of P. ostreatus during surface culturing on a liquid medium. The research results reveal the regular patterns in the formation of aromatic components of macromycetes from lipid precursors. Addition of wheat bran to a growth medium unbalances the total content of aromatic components towards their accumulation in the mycelium. Since fruiting bodies and vegetative mycelium are similar in their biochemical composition, the results of studying the mycelium cultured on a liquid medium allow predicting how aromatic components will be formed in the fruiting bodies of oyster mushrooms.

Microplastic contamination in commercially important bivalves from the southwest coast of India

Due to the ever-increasing production of plastic litter and its subsequent accumulation as microplastic in the environment, the pollution caused by microplastics is considered as a global menace, especially in the coastal ecosystem. Occurrence of microplastics in water and three commercially important bivalves, Viz. green mussel (Perna viridis), edible oyster (Magallana bilineata) and black clam (Villorita cyprinoides) from five different locations of southwest coast of India was studied. The highest abundance of microplastics was observed in water samples from Periyar River (163.67 items L−1). Among bivalves, the highest abundance of microplastics was observed in clams from Periyar River (digestive gland: 22.8 g-1; gill: 29.6 g-1), whereas the lowest abundance was observed in mussels sampled from Vembanad estuary (digestive gland: 5.6 g-1; gill: 8.5 g −1). Fibers were the most prevalent type of microplastics found in bivalve tissues across each location. Microplastics less than 2 mm were the most prevalent based on size. Polypropylene and high-density polyethylene were the two types of microplastics observed based on the results of Raman spectroscopy. No relationship was observed between shell length, tissue weight and microplastic abundance. A strong positive correlation was observed between the microplastic presence in water and bivalve tissues. The usefulness of sedentary bivalves in assessing the aquatic pollution has been validated through this study.

European Flat Oyster (Ostrea Edulis L.) in the Eastern Baltic as Evidence of Long-Distance Trade in Medieval and Early Modern Times

Along most of the European littoral, oysters were appreciated as a wholesome and palatable food from the Stone Age onwards, yet were transported much further from their natural habitats when long-distance trade in marine foodstuffs began in medieval times. The brackish waters of the Baltic Sea are not considered a suitable environment for this mollusc, and therefore all archaeological oyster shell finds are the result of import to the eastern Baltic. In this study, over 1000 shells found in different medieval and early modern archaeological contexts in Estonia were analysed, and the obtained data recorded in a data repository. Some conclusions are set out, based on shell size and shape, and breakage traces, but more detailed taphonomic studies are left for the future. This study identifies the earliest imports of oysters recorded by archaeological material and written sources. Both show records not much earlier than the 16th century AD. Although no information is preserved about the exact origin of oysters imported to Estonia, the oyster beds most probably exploited are those in the central eastern North Sea, i.e., the Wadden Sea.