Rapana Venosa Research Articles

Optimization of Chitosan Extraction Process from Rapana venosa Egg Capsules Waste Using Experimental Design.

New green and sustainable sources were chosen to obtain chitosan, an important material, with many applications in different fields. The present study is focused on egg capsules of Rapana venosa waste as raw material for chitosan oligomers. As previous studies revealed that chitosan extraction from this material takes place with a low yield, the present research aimed to optimize this step. A 22 experimental plan, with three replicates in the center, was proposed to investigate the influence of NaOH concentration and temperature on the yield extraction. After a primary analysis of the experimental data, a favorable temperature value was selected (90 °C) at which the total dissolution of the egg capsules was obtained. Then, at this temperature, the experimental plan was extended exploring the influence of the NaOH concentration on three levels (5, 6, and 7%) and the extraction duration on two levels (60 and 85 min). Based on all experimental data, a neural model was obtained and validated. The neural model was used to maximize the yield, applying Genetic Algorithm (GA) implemented in Matlab®. The resulting optimal solution is: NaOH concentration 6.47%, temperature 90 °C, duration 120 min, with a yield value of 7.05%.

Occurrence and spatial distribution of paralytic shellfish toxins in seawater and marine organisms in the coastal waters of Qinhuangdao, China

In recent years, paralytic shellfish toxins (PSTs) have been prevalent in the coastal waters of Qinhuangdao, the west coast of the Bohai Sea, China. The content of PSTs in shellfish often exceeded the regulatory limit of 800 μg STX equivalent (eq.) kg−1, which poses a serious threat to human health. In this study, two surveys were conducted in May 2021 and May 2022 to investigate the distribution of PSTs in the coastal waters of Qinhuangdao. Seawater, surface sediment, phytoplankton, zooplankton, and other marine organism samples were collected, and the composition and concentration of PSTs were analyzed by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results showed that multiple PST components were detected in all seawater samples collected at different depths, mainly including GTX1/4, GTX2/3, dcGTX2, STX and C1/2, and the highest concentration of PSTs reached 244 ng STX eq. L−1. The sediment samples also contained low levels of C1/2 and GTX2/3. Trace amounts of C1/2 and GTX1-4 were detected in phytoplankton and zooplankton. Moreover, all bivalve shellfish samples were found to contain PSTs, and the scallop Azumapecten farreri and the ark clam Anadara kagoshimensis showed relatively high concentrations of 607 and 497 μg STX eq. kg−1, respectively. In addition, low levels of PSTs were also found in some non-traditional PST vectors, including whelk Rapana venosa, octopus Amphioctopus ovulum, goby Ctenotrypauchen chinensis, and greenling Hexagrammos agrammus. Results of this study improve the understanding of the distribution of PSTs in seawater and marine organisms and the potential risk of persistent PSTs in seawater to marine ecosystems and human health.

СЫРЬЕВАЯ БАЗА ПРОМЫСЛОВЫХ БЕСПОЗВОНОЧНЫХ В АЗОВСКОМ МОРЕ И ДИНАМИКА ЕЕ ОСВОЕНИЯ В 2000–2022 ГГ.

Background. In the context of a low water conent in the Azov Sea along with an increase in its salinity and the background temperature, a decrease in the stocks of stenohaline species of bioresources and an expansion of the species composition of halotolerant species are observed; out of the latter ones, the populations of commercial invertebrates are presently characterized by a drastic increase in their stock abundance and biomass. Relevance. Upon the development of an increased salinity regime of the Azov Sea, it becomes relevant to monitor the undergoing fundamental changes in the exploitable resources of commercial invertebrates. The aim of this work has been to assess the resource potential of commercial invertebrates for the period 2000–2022 and make a forecast of its dynamics under various salinity conditions of the Azov Sea up to 2030. Methods. Analytical data characterizing the status of the exploitable resources of commercial invertebrates in the Azov Sea were originally collected during expeditionary surveys in 2000–2022. To characterize the Azov Sea stocks of commercial invertebrates, standard methods of collecting and analyzing the field samples indicative of the state of their populations have been used. Results. A retrospective analysis of the species composition of commercial invertebrates in the Azov Sea indicates an expansion of the list of commercial species, an increase in their stocks and catch volumes, as well as the potential for further additions to the list of commercial species by involving new ones, currently not targeted by fisheries. Conclusion. The development of the invertebrate fishery creates a crucial alternative to the deteriorated catches of commercial fish species and may facilitate the preservation of a small fishing fleet in the Azov Sea, preventing its decline. In the case if salinity remains in the 14.5–16.5 ‰ range or increases to 18.5 ‰, there will be maintained the favorable conditions for increasing the catches of molluscs (veined rapa whelk, mussels, unequal arc), crustaceans (shrimps, Gammarus, Artemia), insects (chironomids), and jellyfish.

Handling- or digestion-limited predators: the role of body mass and habitat complexity in predator functional response

The predator functional response quantifies the per capita feeding rate of predators as a function of prey density and is a key element of feeding interactions. Variations in its parameters are strongly associated with interaction strength and population dynamics. We examined 18 functional responses within marine whelk-bivalve systems, varying predator body size, prey species, and habitat structure. Our findings suggest that the marine whelk Rapana venosa is handling-limited, a predator type that has received less attention in previous research. We propose further categorizing handling-limited predators into 2 types: pursuit-limited (where maximum feeding rate could be influenced by habitat complexity) and ingestion-limited (where maximum feeding rate is impacted not by habitat complexity, but by predator-prey body mass ratios and prey defense strategy). We found that handling time scales negatively with predator-prey body mass ratios, but this trend exhibits layers of complexity. We propose that the transition from handling to digestion limitation with increasing predator-prey body mass ratios underlies this trend. Our study also confirms the importance of prey types, in addition to known effects of body mass ratios and habitat structure. In summary, our study reveals that simple assumptions about body masses and prey defense strategy may usefully refine estimates of feeding interactions in complex food webs.

Determination of Nutrient Composition and Total Volatile Basic Nitrogen (TVB-N) Levels in Sea Snail (Rapana venosa Valenciennes, 1846) Process Steps

Deniz salyangozu (Rapana venosa)' nun su ürünleri işleme tesisinde her bir işleme basamağı için besin içeriği ve kimyasal kalite parametresi olarak TVB-N (Toplam Uçucu Bazik Azot) içeriğinin saptanması amaçlanmıştır. Araştırmada işleme tesisine hammaddenin girişinden sonra deniz salyangozu (Rapana venosa) ’nun işlem basamaklarına göre haşlama, yıkama, kabuk çıkarma, kalibrasyon, şoklama, (24 saat -35 °C ile -40 °C) ve muhafaza (-18 °C’ de 1 hafta) olmak üzere toplam altı aşamadan örnekler alınarak incelenmiştir. Yapılan analiz sonuçlarına göre işleme aşamalarında ham nem içerikleri sırasıyla %73.32±0.90 (haşlama), %70.53±0.17 (yıkama), %72.67±0.27 (kabuk çıkarma), %75.51±0.57 (kalibrasyon), %76.79±0.14 (şoklama) ve %76.01±0.10 (muhafaza) olarak bulunmuştur. Analiz sonuçlarına göre ham kül değerleri içerikleri sırasıyla %2.49±0.03 (haşlama), %2.31±0.27 (yıkama), %2.74±0.50 (kabuk çıkarma), %1.25±0.14 (kalibrasyon), %1.08±0.16 (şoklama) ve %1.09±0.14 (muhafaza) olarak bulunmuştur. Analiz sonuçlarına göre ham protein içerikleri sırasıyla %19.44±0.07 (haşlama), %21.46±0.70 (yıkama), %20.07±0.08 (kabuk çıkarma), %18.92±0.72 (kalibrasyon), %19.28±0.57 (şoklama) ve %18.17±0.41 (muhafaza) olarak tespit edilmiştir. Analiz sonuçlarına göre ham yağ içerikleri sırasıyla %0.83±0.52 (haşlama), %1.65±0.65 (yıkama), %0.53±0.0 (kabuk çıkarma), %0.53±0.00 (kalibrasyon), %0.49±0.04 (şoklama) ve %0.56±0.04 (muhafaza) olarak tespit edilmiştir. Deniz salyangozu (Rapana venosa) nun işleme aşamalarında TVBN analiz sonuçları ise haşlama için 8.20±0.08 mg/100g, yıkama için 9.61±0.09 mg/100g, kabuk çıkarma için 12.26±0.14 mg/100g, kalibrasyon için 8.23±0.16 mg/100g, şoklama için 8.94±1.02 mg/100g ve muhafaza için 6.87±0.15 mg/100g olarak bulunmuştur. Analiz sonuçlarında taze ve soğutulmuş salyangoz et numuneleri için TVB-N limitinin işleme aşamalarında tüketilebilir oranda olduğu belirlenmiştir.

Integrated mRNA and miRNA transcriptomic analysis reveals the response of Rapana venosa to the metamorphic inducer (juvenile oysters)

Metamorphosis, as a critical developmental event, controls the population dynamics of most marine invertebrates, especially some carnivorous gastropods that feed on bivalves, whose population dynamics not only affect the maintenance of the ecological balance but also impact the protection of bivalve resources; therefore, the metamorphosis of carnivorous gastropods deserve attention. Here, we investigated the mechanism underlying the response of the carnivorous gastropod Rapana venosa to its metamorphic inducer juvenile oysters through integrated analysis of miRNA and mRNA profiles. According to the results, we speculated that the AMPK signaling pathway may be the critical regulator in the response to juvenile oysters in R. venosa competent larvae. The NF-kB and JAK-STAT signaling pathways that regulated apoptosis were also activated by the metamorphic inducer, which may result in the degeneration of the velum. Additionally, the significant changes in the expression of the SARP-19 precursor gene and protein cibby homolog 1-like gene may indicate that these signaling pathways also regulate growth and development during metamorphosis. This study provides further evidence that juvenile oysters can induce metamorphosis of R. venosa at the transcriptional level, which expands our understanding of the metamorphosis mechanism in carnivorous gastropods.

Feeding intensity and daily mussel consumption of Rapa whelk (Rapana venosa) in the north-western Black Sea

Based on an experiment carried out in the north-western Black Sea (Snake Island), the feeding behavior of the Rapa whelk (Rapana venosa Valenciennes, 1846) was analyzed in relation to its size (N = 58; shell height: 30–90 mm). Mediterranean mussels (Mytilus galloprovincialis Lamarck, 1819) were placed in experimental cages with R. venosa to be used as food. It was found that the size of the prey was determined by the size of the predator. The mussels with a shell length of 20−40 mm were most affected by R. venosa. It was determined that the predator’s contribution to the deposition of mussel shells in the bottom sediments is also associated with its size. Feeding intensity varies from 41 mg to 99 mg of the total mass of mussels per 1 g of the total mass of R. venosa per day, depending on the size of the predator. The daily consumption of mussel soft tissue varied from 0.189 g ind.−1 per day−1 in small R. venosa specimens to 0.917 g ind.−1 per day−1 in large predators. Regression equations were obtained between the length and mass of the mussels consumed (total mass, soft tissue mass and shell mass) and the shell height of the predator.

Chemical status evaluation of the Romanian Black Sea marine environment based on benthic organisms’ contamination

The use of living organisms to provide information on the quality of aquatic environments is now a widely accepted methodology for assessing contaminant bioavailability. Molluscs have developed tolerance mechanisms towards environmental stressors and can accumulate a large range of contaminants. The assessment of marine environment quality was based on heavy metals (HM), persistent organic pollutants (organochlorine pesticides – OCPs and polychlorinated biphenyls - PCBs) and polynuclear aromatic hydrocarbons (PAHs) analysis in Mytilus galloprovincialis, Rapana venosa, Anadara kagoshimensis species sampled during 2016 - 2020 along Romanian Black Sea coast. Toxic metals (cadmium, lead) had bioaccumulation levels below threshold values in most molluscs samples investigated. Cadmium registered few values (15%) surpassing maximum admissible levels, in all three species. Data evaluation demonstrated the maintenance of a high level of concentrations of persistent organic pollutants in the mollusc tissue, but also of the exceedances of the values that characterize the good ecological status of these compounds. Polynuclear aromatic hydrocarbons showed a declining trend and no exceeding of the maximum allowed limit for benzo[a]pyrene was recorded in the last years. In consequence, the overview assessment based on “OneOutAllOut” (OOAO) approach, considering all groups of substances, indicates a bad chemical status for this period.

Screening the Implementation of HACCP Principles in the Romanian Seafood Industry. Case Studies and Optimisation Scenarios

HACCP (Hazard Analysis and Critical Control Points) is considered an efficient tool for both the food industry and health authorities in preventing foodborne diseases. Seafood and fishery products in particular may harbor biological, chemical and physical hazards, as their chemical composition makes them much more perishable than meat products and constitute better substrates for growth of pathogenic bacteria. In this context, the aim of this paper was to perform an in-depth analysis of the HACCP implementation for the major shellfish [rapa whelk Rapana venosa (Valenciennes, 1846) and Black Sea mussels Mytilus galloprovincialis Lamarck, 1819] and marine/freshwater fish species [Danube shad Alosa immaculata Bennett, 1835; sprat Sprattus sprattus (Linnaeus, 1758); mackerel Scomber scombrus Linnaeus, 1758; various carp species] processed by the Romanian seafood industry at the Black sea coast. Field visits to the processing plants were performed in February and March 2022 and the application of the HACCP plan was documented, in order to identify potential weaknesses and drawbacks. Optimization scenarios for each of the two case studies were considered, to foster the safe and responsible development of the sector in Romania.

Rapa Deniz Salyangozu (Rapana venosa Valenciennes, 1846) Populasyon Özelliklerinin Araştırılması, Çamburnu Koyu (Trabzon)

In the present study, some population characteristics of Rapa Sea snail (Rapana venosa) samples collected from coastal zone of the Eastern Black Sea were investigated. For this purpose, Rapa whelk samples were collected by snorkeling from depths of ∼7-13 m in Çamburnu Bay (Trabzon) in the year 2020. Morphometric measurements such as shell size (shell length and width) and operculum size (aperture length and width) as well as total body weight were measured using a caliper with an accuracy of 0,01 cm and a digital balance with an accuracy of 0,01 g, respectively. Metal levels [zinc (Zn), copper (Cu), cadmium (Cd) and lead (Pb)] in muscle and hepatopancreas tissues of gastropods were measured by inductively coupled plasma atomic emission spectroscopy (ICP-OES). It was observed that 48,76% of the sampled sea snail population was female and 51,24% was male. The mean shell length-shell width, aperture length-aperture width, and snail total body weight were determined as 35,6-27,2 mm, 26,5-11,7 mm and 14,6 g, respectively. In this study, the relation showing the relationship between the total shell length and the total body weight of the sea snail was calculated as W=0,0034*SL2,63. The least accumulation was observed at the level of lead and cadmium, when the metals in the sea snail muscle tissue were examined. On the other hand, when the metals in the hepatopancreas tissue were examined, excessive accumulation was observed at the level of zinc and copper. In addition, a positive correlation was determined between the metal accumulation in the tissues and the wet weight of the unshelled snail and the aperture length, respectively.

Selective Cytotoxicity and Changes in Protein Expression of T24 Bladder Carcinoma Permanent Cell Line after Treatment with Hemocyanins.

Some molluscan hemocyanins (Hcs) have significant immunological and antitumor potential, enabling their application in oncology. The antitumor activity of Hcs from marine snails Rapana venosa (RvH), giant keyhole limpet Megathura crenulata (KLH) and garden snails Helix lucorum (HlH), as well as their different derivatives, were studied in vitro on a permanent T24 cell line of bladder cancer and normal urothelial cell line HL 10/29 compared to doxorubicin. The antiproliferative activity of the tested Hcs was determined using the WST-1 assay and BrdU ELISA assay. Morphological changes in both urothelial cell lines were confirmed by fluorescence microscopy. The proteomic analysis of a bladder cancer cell line before and after treatment with functional unit (FU) βc-HlH-h using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and mass spectrometry revealed differences in the expression of some proteins. Studies prove that the T24 tumor cell line is dose- and time-dependent, sensitive to the action of the tested isoforms, and it glycosylated FU of these hemocyanins. Selective inhibition of T24 cell growth was observed after incubation with structural subunits (βc-HlH, RvHI and RvHII) and FUs (βc-HlH-h and RvHII-e). Additionally, fluorescent microphotographs did not show apoptotic or necrotic alterations in the normal urothelial cell line HL 10/29. The FU βc-HlH-h demonstrated the highest antiproliferative effect (similarly to doxorubicin), in which predominantly apoptotic and less late apoptotic or necrotic changes in the tumor cells were observed. Several downand up-regulated proteins identified by proteome analysis may be associated with the apoptosis pathway. The present study illustrated the selectivity of the cytotoxic effect of Hcs against the Т24 cancer cell line. This is the first report of protein expression in T24 human bladder cancer cells under the influence of FU βc-HlH-h. That is probably due to the specific oligosaccharide structures rich in methylated hexoses exposed on the surface of βc-HlH-h.

Molecular response and developmental speculations in metamorphosis of the veined rapa whelk, Rapana venosa.

Metamorphosis is the short developmental stage characterized by dramatic ontogenetic changes that occurs in most animals. However, this important process remains largely unclear in marine invertebrates. In this study, we performed the sequential RNA sequencing of a representative mollusk, the rapa whelk (Rapana venosa), that is undergoing metamorphosis and conducted differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) to investigate the overall and dynamic transcriptome responses. The results revealed that the expression of cytochrome P450 2A and 3A were upregulated during metamorphosis, while the expression of H/ACA ribonucleoproteins increased 4 h after metamorphosis induction (M4 stage), indicating that R. venosa mainly responded to the pelagobenthic changes. At the M24 stage, the enrichment of V-type proton ATPase and insulin indicated the complete development of secretory organs and initiation of hormone secretion. Furthermore, at the M48 stage, the enrichment of zinc metalloproteinase and conotoxin indicated a well-developed predation system that requires exogenous nutrition. Finally, during the PL stage, the genes associated with growth control were highly enriched, implying that R. venosa had completed metamorphosis and has entered the period of rapid growth. Therefore, our study provides useful transcriptomic resources for R. venosa and contributes new insights that may assist in elucidating the mechanisms underlying metamorphosis in marine invertebrates.

Rapana venosa (Valenciennes, 1846) in the Donuzlav Bay and adjacent Black Sea area

The predatory gastropod mollusk Rapana venosa is included in the list of the 100 most dangerous invasive species of the Black and Mediterranean Seas, which determines the relevance of studying the species’ local populations in the areas of introduction. The first studied Rapa whelk population in Donuzlav Bay (NW Crimea) was one of the last to form and differs from populations in other areas of the Black Sea. Based on the results of studies in 2020, the characteristics of the population structure of R. venosa inhabiting the Donuzlav Bay and the adjacent marine area are shown. The data obtained are compared with the population characteristics of the Rapa whelk from other areas of the Black Sea. It is shown that at the stage of stabilization of the metapopulation, the phenotype of the adapted “norm” R. venosa of the Black Sea was formed.

Trace elements in edible tissues of the veined rapa whelk (Rapana venosa) in the southern Black Sea, Türkiye: sex, monthly, and age variations and human consumer health risk.

Coastal areas face significant pressures from a variety of human activities, owing primarily to population growth in these areas. Human activities produce a variety of contaminants, including trace metals, which are common forms of contamination that enter marine ecosystems. This study was carried out to provide information on trace element concentrations (Hg, Pb, Cd, Cu, and Zn) in the muscles of Rapana venosa (Valenciennes, 1846) available on Sinop coasts of the southern Black Sea and to evaluate the possible risk associated with their consumption. The minimum and maximum values (mg/kg wet weight) of trace elements in the edible tissue of R. venosa decreased in the following order: Zn (1.75-8.53) > Cu (0.41-4.6) > Cd (0.021-0.255) > Pb (0.013-0.037) > Hg (0.010-0.035). The measured levels of all the trace elements in the present study were lower than the limits permitted by the European Community Regulation (EU), Turkish guideline, and the UK Ministry of Agriculture, Fisheries and Food (MAFF). The hazard index value of Hg, Cd, Cu, and Zn for the veined rapa whelk is lower than standard 1, demonstrating that ingestion of this mollusk from the southern Black Sea does not result in overexposure to these contaminants. The risk index value for human cancer risk of Pb for all seasons was found to be insignificant. When comparing the levels of elements in males and females, significant differences were found in some months for all the metals. In general, the trace elements were detected in higher concentrations in females than in males. Both females and males have accumulated less trace elements with increasing age. This study was the first to show the distribution of trace elements as a function of age in R. venosa.

Estimating ecological carrying capacity for stock enhancement in marine ranching ecosystems of Northern China

Marine ranching has been proposed as a promising solution to manage the depleted coastal fishery ecosystem in recent decades across China. Marine ranching integrates the practices of artificial habitat-based with aquaculture-based enhancement. Assessing the ecological carrying capacity of target species for enhancement is a precondition for determining the optimal numbers for release, particularly for those species whose habitat restrictions have been eliminated through the construction of artificial habitats in the marine ranch. A responsible approach to stock enhancement aims not only to increase total yield and stock abundance but also to consider any potential effects on ecosystem structure and function. A time-dynamic, ecosystem model was constructed using Ecopath with Ecosim for the Laizhou Bay (Bohai Sea) marine ranching ecosystem in the nearshore waters of northern China. Two sedentary target species with potential for stock enhancement, i.e., the carnivorous red snail Rapana venosa and the detritivorous sea cucumber Apostichopus japonicus, were selected to simulate and estimate their ecological carrying capacities and project their overall effects on the ecosystem. Ecological carrying capacity was defined as the maximum standing stocks of the target species that would not cause “unacceptable” impacts on the ecosystem function and resilience, i.e., not cause any other group’s biomass to fall below 10% of its original biomass. The ecological carrying capacities estimated for R. venosa and A. japonicus were 623.46 and 200.57 t·km−2, respectively, corresponding to 7.8 and 5.0 times higher than their current standing stocks. Simulations of R. venosa enhancement showed distinct effects of increased target species abundance on other functional groups and ecosystem properties. An increase in red snail biomass caused negative impacts on the biomass of most other functional groups and ecosystem indicators, such as Finn’s cycling index, transfer efficiency, and Kempton’s Q index. In contrast, the simulated A. japonicus enhancement had relatively few impacts, and the biomasses of most other functional groups and ecosystem indicators did not change or changed very slightly (<5%). The current model framework provides a means of estimating the ecological carrying capacity in commercial-scale stock enhancement practices and avoiding potential ecological risks for marine ranching in northern China.

Larvae of a marine gastropod and a marine bivalve share common gene expression signatures during metamorphic competence

Many aquatic invertebrates undergo an indirect development, a biphasic life cycle which encompasses the transformation of free-swimming larvae into benthic juveniles via settlement and metamorphosis. During this transition, metamorphic competence is a crucial developmental stage that allows larvae to swim and feed in the planktonic realm while retaining the ability to settle and metamorphose in response to environmental cues. Although there have been substantial efforts to decipher the molecular mechanisms underlying this event in several molluscan species, the conserved biological pathways that are crucial to enable this transition across species are not well understood. Here, we performed a comparative analysis of the developmental transcriptomes between bivalve Crassostrea gigas and gastropod Rapana venosa. We particularly explored the common gene expression signatures that may underlie their larval competence. We showed that, although the developmental transcriptomes differed remarkably between C. gigas and R. venosa, they likely shared a plethora of genes (n = 690) that exhibited similar expression signatures during their larval competence. Gene Ontology enrichment and expression analyses further indicated that competent larvae of both species exhibited up-regulation of pathways associated with response to stimuli, metal ion binding and transport, and neuronal development, but showed down-regulation of pathways that were mainly involved in cilium assembly and organ development. Using oyster and whelk as models, our study suggests that regulation of these conserved pathways is crucial for their subsequent settlement and metamorphosis and may represent a universal mechanism that enables the pelagic-to-benthic transition in a broader range of marine invertebrates.

Coastal aquaculture farms for the sea cucumber Apostichopus japonicus provide spawning and first-year nursery grounds for wild black rockfish, Sebastes schlegelii: A case study from the Luanhe River estuary, Bohai bay, the Bohai Sea, China

Aquaculture farms are known to attract wild organisms from nearby areas. Sea cucumber Apostichopus japonicus aquaculture farms in Bohai Bay, the Bohai Sea, China, might provide spawning and nursery grounds for wild black rockfish Sebastes schlegelii populations. To identify the above, we studied the variation in the numbers of S. schlegelii larvae (and length-categories as a percentage of the natural population) via ichthyoplankton surveys by months from January to October 2020, and assessed the food web structure and energy flow distribution of the farm and trophic links of S. schlegelii natural stock by using Ecopath modeling in July 2016 to August 2017. Larvae with a length between 3.90-5.80 mm were observed in the farm in May 2020, the juveniles with an estimated trophic level of 4.31. Juveniles used the farms as first-year nursery ground, and then they swam into deeper waters in August of the following year. MTI analysis showed increasing biomass of S. schlegelii might result in a decrease in the biomass of crustacea, and had positive and negative impacts on mollusk and Hexagrammos otakii biomass. We argued that aquacultural infrastructures constructed by artificial reefs could be used as a fisheries management tool to enhance S. schlegelii stocks and that monitoring of other marine organisms, such as oysters, Rapana venosa, Charybdis japonica, and Asterias spp. etc., was necessary to maintain sustainable exploitations of aquacultural farm ecosystems. A paucity of knowledge surrounding the interactions between aquaculture farms and wild organisms needs furthermore researches.

Detection of Human and Fish Viruses in Marine Gastropods.

Simple SummaryMollusca is one of the largest phyla in the animal kingdom that includes more than 100,000 existing species living in aquatic and terrestrial habitats. Within this phylum, marine molluscs are considered an important resource for fisheries, and gastropods represent 2% of marine molluscs fished worldwide. Similar to bivalves, gastropods are susceptible to environmental contamination, and they are able to accumulate microorganisms. However, despite their economic importance, only few studies have focused on the monitoring of viral contamination in their tissues and their possible role as carriers. In this study, the presence of human pathogenic viruses such as hepatitis A virus, but not noroviruses, different to the situation in bivalve molluscs, was found in gastropods. This finding suggests a low risk of food-borne viral infections for gastropod consumers. Furthermore, one of the most impactful pathogens for marine aquaculture, nervous necrosis virus (NNV), was detected in gastropods. However, the animal tissues examined did not show any histological changes, suggesting the absence of a pathogenic effect of NNV in the analyzed gastropods.Marine gastropods represent a major food source for higher trophic levels and an important source of animal protein for humans. Like bivalve molluscs, gastropods can accumulate several types of contaminants; however, the bioaccumulation of microorganisms, particularly viruses, has been poorly investigated in these animals. This study focused on gastropods (Tritia mutabilis, Bolinus brandaris and Rapana venosa) collected during the fishing season from 2017 to 2021 in the north-western Adriatic Sea, and on clams (Ruditapes philippinarum) harvested in the same geographical area, in order to evaluate the presence of human and fish viruses in their tissues. A virological investigation was carried out on the digestive gland using molecular methods. The presence of hepatitis A virus was detected in one sample, whereas noroviruses were not present in the investigated specimens. Regarding fish viruses, it was possible to detect the presence of nervous necrosis virus (NNV) in 26.5% of the analyzed gastropods; however, the histological examination did not show any pathological changes in the nervous tissue in both NNV-positive and -negative batches. As a whole, the investigated gastropods showed the ability to bioaccumulate viruses; however, lower contamination by human viruses compared to bivalve molluscs was pointed out, posing a minor concern to human health.

Population genetic indices of veined Rapa whelk groups of the Black Sea remote regions

Abstract Genetic structure and genetic distance of Rapana venosa populations from remote regions of the Black Sea (Odessa Bay and eastern Crimea, Ukraine) were defined. Despite the significant difference in morphometric parameters, the investigated samples of mollusks are genetically very similar, and the distance between them is at the level of local populations. Common features of observed groups of Rapana in the northern part of the Black Sea are the unequal occurrence of some alleles and genotypes, a high level of heterozygosity and nonequilibrium in the Hardy-Weinberg equation. The gene flow is the most significant of the evolutionary factors that form the genetic structure of Rapana venosa populations.

Natural resource governance in the Bulgarian Black Sea: Identifying context-sensitive institutional arrangements

ABSTRACT The main objective of this article is to study the local governance dynamics around natural resources in the delimitated Marine reserve Kaliakra, on the Bulgarian Black Sea coast. Our research focuses mainly on formal/informal institutional arrangements for that zone. This article aims to achieve several objectives. First, it seeks to contribute to the common pool resources (CPR) theories, applying Ostrom’s socio-ecological framework and broaden its scope to the larger institutional context. Second, it will focus specifically on one marine protected area and the harvesting of the invasive species Rapana Venosa in the Bulgarian Black Sea. Although formal institutions are important in setting the rules for natural resource governance, this study finds that informal institutions, specific to the country’s context, tend to shape the results and objectives of this governance and reflects the socio-economic characteristics of the macro context in which it is embedded.