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Seasonal tissue concentrations of heavy metals, antioxidant enzymes, immunological components, and water quality parameters were investigated during 1 year in the ark clam, Barbatia decussate, from the coast of Lengeh port, located in the north of the Persian Gulf, Iran. The tissue accumulation of the heavy metals (Cd, Pb, Hg) significantly increased accumulations in late autumn and winter (P 0.01). Seasonal changes were also observed in metal-induced biochemical components. In this regard, the malondialdehyde (MDA) levels and the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) elevated throughout spring and summer and then declined during autumn and winter (P < 0.01). Phagocytosis activity significantly decreased from December to February and then increased from March to September (P

The impact of low salinity on morphology and function of hemocytes in ark clam species Anadara kagoshimensis was investigated using light microscopy and flow cytometry. In the control group, the water salinity was adjusted to 19.6‰, and the experimental group was maintained at 14.8 and 8.8‰. Two cell types, amebocytes and erythrocytes, were identified in control group of ark clams. Erythrocytes constituted the main type of the cells; their share was 92.3 ± 3.9%. Hyposalinity changed that proportion: the number of amebocytes decreased by 2.7 times and number of erythrocytes increased by 7.6 times. Morphometric characteristics of hemocytes did not show statistically significant changes. As the salinity decreased, the number of erythrocyte ghosts in hemolymph increased (by 3.5 times at salinity of 8.8‰) and, in hemocytes, the reactive oxygen species (ROS) production grew (by 3.5 times at salinity of 8.8‰).

Марикультурные хозяйства традиционно расположены в прибрежных участках, где моллюски могут подвергаться воздействию гипоксии. Культивирование в условиях дефицита кислорода приводит к снижению темпов роста, вспышкам заболеваний на фермах и массовой гибели моллюсков. Методом проточной цитометрии исследовано влияние краткосрочной гипоксии на функциональные показатели гемоцитов анадары (Anadara kagoshimensis). Контрольную группу содержали при 6,7–6,8 мг O2·л−1, опытную — при 0,4–0,5 мг O2·л−1. Экспозиция — 24 часа. Содержание кислорода в воде снижали, продувая её газообразным азотом. В гемолимфе моллюска на основании относительного размера и относительной гранулярности идентифицировано две группы гемоцитов: гранулоциты (эритроциты) и агранулоциты (амёбоциты). Эритроциты — преобладающий тип клеток в гемолимфе A. kagoshimensis: их доля составила более 90 % от общего числа клеток. Суточная гипоксия не привела к изменениям клеточного состава гемолимфы анадары. Способность к продукции активных форм кислорода и уровень смертности гемоцитов моллюсков экспериментальной группы также остались на уровне контрольных значений. Результаты проведённого исследования свидетельствуют о толерантности анадары к условиям острого дефицита кислорода.

Neptunomonas concharum JCM17730 was isolated from an ark clam sample and characterized as a mesophilic bacterium. The genome of N. concharum JCM17730 contains thirteen genes related to polyhydroxyalkanoates (PHA) metabolism. Three PHA synthase encoding genes were identified, and phylogenetic analysis of enzyme sequences suggested the presence of two class I PHA synthases and one class III PHA synthase. The PHA synthases of N. concharum were heterologously expressed with acetyl-CoA acetyltransferase and acetoacetyl-CoA reductase in Escherichia coli to confirm the catalytic activity of each PHA synthase. Recombinants harboring different PHA synthase exhibit important distinctions in poly-3-hydroxybutyrate synthesis ability under various temperatures. Decreased cultivation temperature (≤30 °C) significantly improved PHB titer and content. This is the first report on characterization of PHA synthases from the marine genus Neptunomonas and would provide molecular basis for PHA production using Neptunomonas species.

Filter-feeding shellfish are common benthos and significantly affect the biogeochemical cycle in the shallow coastal ecosystems. Ark clam Scapharca subcrenata is one of the widely cultured bivalve species in many coastal areas owing to its tremendous economic value. However, there is little information regarding the effects of the bioturbation of S. subcrenata on the fluxes of nutrient exchange in the sediment-water interface (SWI). In this regard, S subcrenata was sampled during October 2016 to determine the effects of its bioturbation activity on the nutrient exchange flux of the SWI. The results showed that the biological activity of S. subcrenata could increase the diffusion depth and the rate of the nutrients exchange in the sediments. The bioturbation of S. subcrenata could allow the nutrients to permeate into the surface sediments at 6−10 cm and increase the release rate of nutrients at the SWI. The releasing fluxes of DIN and PO43−-P in the culture area were found to be around three times higher than that in the non-cultured region. The culture of S subcrenata has been proved to be an important contributor to nutrient exchange across the SWI in the farming area of Haizhou Bay. Nutrients exchange in the SWI contributes a part of 86% DIN, 71% PO43−-P and 18% SiO32−-Si for the aquaculture farm.

We studied the specific features of the joint activity of the enzyme and low-molecular weight parts of the antioxidant (AO) complex in the tissues of two species of the Black Sea bivalve mollusks with different resistance to oxidative stress: a native species, the Mediterranean mussel Mytilus galloprovincialis Lam., and an invader, the ark clam Anadara kagoshimensis (Tokunaga, 1906). In the hepatopancreas and the gills and foot of mollusks, the activity of glutathione peroxidase (GP), glutathione reductase (GR), superoxide dismutase (SOD), catalase, and the level of reduced glutathione (GSH), as well as the contents of glucose, amino acids, and products that react with thiobarbituric acid (TBA-reactive products), have been analyzed. The enzyme part had a leading role in AO defense in the tissues of the Mediterranean mussel. This is indicated by higher activities of GP (hepatopancreas, gills) and SOD (hepatopancreas, foot) but a smaller content of GSH (gills, foot) as compared with ark clam. In ark clam tissues, the role of low-molecular weight part is significant, which is confirmed by the higher GSH level (gills, foot) in combination with the higher activity of GP (foot) and SOD and catalase (gills) than that observed in the Mediterranean mussel. Unlike the mussel, ark clam tissues showed a more effective joint activity of SOD, catalase, and glutathione system, which resulted in a significantly lower content of LPO products than that found in all of the studied Mediterraneanmussel tissues. These features of the joint activity of the enzyme and low-molecular weight parts of the AO complex of the Mediterranean mussel and ark clam largely determine the difference in the resistance to oxidative stress in the mollusks of these species. The results confirm the prevailing idea of the ark clam as one of the most competitive invaders as compared with native species; it has successfully mastered new biotopes in the Azov-Black Sea basin and has become an important component of benthic communities.

High temperature is a risk factor for vibriosis outbreaks. Most vibrios are opportunistic pathogens that cause the mortality of aquatic animals at the vibrio optimal growth temperature (~25 °C), whereas a dominant Vibrio kanaloae strain SbA1-1 is isolated from natural diseased ark clams (Scapharca broughtonii) during cold seasons in this study. Consistent symptoms and histopathological features reappeared under an immersion infection with SbA1-1 performed at 15 °C. The pathogenicity difference of SbA1-1 was assessed under different temperatures (15 °C and 25 °C). The cumulative mortality rates of ark clams were significantly higher at the low temperature (15 °C) than at the high temperature (25 °C), up to 98% on 16th day post SbA1-1 infection. While the growth ratio of SbA1-1 was retarded at the low temperature, the hemolytic activity and siderophores productivity of SbA1-1 were increased. This study constitutes the first isolation of V. kanaloae from the natural diseased ark clams (S. broughtonii) in cold seasons and the exposition of the dissimilar pathogenicity of SbA1-1 at a different temperature. All the above indicates that V. kanaloae constitutes a threat to ark clam culture, especially in cold seasons.

Composite materials have been created for the applications of dental veneer from a mixture of raw materials : hydroxyapatite (HAp) powder from ark clam shells and epoxy resins by cold compression method with variations of composition hydroxyapatite (HAp) powder : epoxy resin (75 : 25)%wt, (80 : 20)%wt, (85 : 15)%wt, (90 : 10)%wt, dan (95 : 5)%wt. Sampling is created in three steps. The first step of ark clam shells powder is treated by smoothing it with a particle size of 200 mesh and heated at 900oC for 2 hours after it had been synthesized into hydroxyapatite (HAp) powder. The second step of the filler (hydroxyapatite powder) is mixed with dry mixing and then mixed with epoxy resin as a matrix. The third step of the homogeneous mixture is then inserted into the mold and compacted by heat to be more dense with pressure of 300 MPa or 3 ton held for 5 minutes at 27°C. The characterization results showed that the optimum composition of hydroxyapatite powder: epoxy resin (75 : 25)%wt with density value 0,1185 x 103 kg/m3, water absorption 1,163%, composed of -PO4 (phosphate), -CO3 (carbonate) and HOH groups. Mechanical properties with fracture strength 116 MPa, tensile strength 66,12 MPa, modulus of elasticity 3297,99 MPa and brinell hardness 75,87 HBR whose characterization results have met the conventional dental veneer standards.

The effect of three different initial alkaline pH values (pH= 8, 9 and 10) in synthesised hydroxyapatite (HA) via a wet chemical precipitation approach was investigated. Waste ark clam shells (ACS) were used in this work as a source of calcium oxide in order to utilise waste materials in the production of synthetic Hydroxyapatite (HA). The HA was treated at different sintering temperature from 200 to 1000 °C to study the effect on the physical, the structural properties, the phase formation, the Vickers microhardness and the molar ratio of calcium to phosphate (Ca:P). From the results, the crystallite size and density of the HA obtained were increased as the sintering temperature increased. However, the appearance of biphasic HA and β-tricalcium phosphate (β-TCP) was detected at pH 9 with 1000 °C, but did not occur at pH 8 and 10. In addition to the obtained results, it was clearly identified that the formation of β-TCP in the HA phase is related to the initial pH value, sintering temperature and Ca:P ratio. The Vickers microhardness showed that the single-phase HA was the hardest one compared to the biphasic HA/β-TCP. It shows the optimal value of the Vickers microhardness for the single-phase HA with a pH 10 at 1000 °C is 4.15 MPa.

Nature in Singapore, 14, 1-2

Endothelial dysfunction is directly involved in consequence of various metabolic syndromes such as diabetes and hypertension. In this study, we investigated the preventive effects of two ark clams [ark shell (AS,Scapharca subcrenata) and granular ark (GA,Tegillarca granosa)] on endothelial dysfunction induced by a high-fat diet. Wistar rats were divided into four groups as follows: control (normal diet), HF (high-fat diet), AS (high-fat diet + 5% AS powder), and GA (high-fat diet + 5% GA powder) for 12 weeks. AS and GA diets enhanced vascular reactivity of the rat thoracic aorta and significantly increased expression levels of vascular relaxation-related proteins (p-Akt-ser473 and p-eNOS-ser1177). Ark clam supplement reduced endothelin-1 expression level, as compared to the HF group. Additionally, AS and GA showed a trend of improving insulin sensitivity compared to HF. Our results suggest that AS and GA enhance vascular reactivity and ameliorated endothelial dysfunction induced by a high-fat diet.

The blood cockle Larkinia grandis is a commercially important resource in the Gulf of California, but little information is available on this species. In this study, the interactions between body weight (BW) and shell length (SL), height (SH), and width (SW) were evaluated in a L. grandis population in the Gulf of California, Mexico. Eighty cockles were hand-picked monthly from August 2017 to July 2018 near and/or under mangrove trees on the southeastern coast of the Gulf of California. The range of shell measurements (SL = 142.00–44.57 mm, SH = 85.50–31.15 mm, SW = 76.56–32.03 mm) indicates that the sampled population was dominated by adult specimens. Only the coefficient of variation for BW exhibited high dispersion (23%–45%). The potential relationships between BW and SL, SH, and SW were non-linear. The strongest interaction was found between BW and SW (R2 = 0.934), with the BW–SW relationship best describing the growth of this ark clam. All shell dimension–weight relationships were significant (P ≤ 0.05), indicating both negative (SL–SW and SH–SW) and positive (SL–SH, BW–SL, BW–SH, and BW–SW) allometric growth. The b values ranged from 0.8950, for the LogSH–LogSW relationship, to 2.6240, for the LogBW–LogSH interaction. This preliminary information is useful for developing conservation and sustainable exploitation strategies for this species, which is of economic importance to this region.

In this paper, the relationship between bodyshelldimensions and growth parameters ofark clam (Anadara inaequavalvisBruguière, 1789) were estimated for theBlack Sea. At the end of this research, therewas a significant relationship between bodysize and shell dimensions. In addition tothis, the Von Bertalanffy growth parameterswere found as L∞=8.61 mm, K= 0.25 and t0= -0.43 yr-1. Mortality rates were alsoanalyzed for the ark clam as Z= 0.95 yr-1,M= 0.77 yr-1, F= 0.18 yr-1. This research isimportant in terms of the first study of bodyshelldimension relationships and mortalityrates for Anadara inaequavalvis from theBlack Sea. The ark clam can use a descriptorfor the Good Environmental Status (GES)according to Marine Strategy FrameworkDirective (MSFD) 2th Task Group inEuropean Commission., Bu çalışmada Karadeniz’de Anadara inaequavalvis (Bruguière, 1789)’in vücut-kabuk boyuilişkileri ve büyüme parametreleri tahmin edilmiştir. Sonuç olarak, vücut ölçüleri ile kabukboyutları arasında önemli bir ilişki gözlenmiştir. Buna ek olarak, Von Bertalanffy büyümeparametreleri L∞=8.61 mm, K= 0.25 and t0= -0.43 yr-1 olarak bulunmuştur. Ayrıca, ölümoranları Z= 0.95 yr-1, M= 0.77 yr-1, F= 0.18 yr-1 olarak hesaplanmıştır. Bu çalışma, Anadarainaequavalvis’in vücut-kabuk boyutları arasındaki ilişki ve ölüm oranlarının tahmin edildiği ilkçalışma olma özelliği taşımaktadır. Bu tür Avrupa Komisyonu’nun Deniz Stratejisi ÇerçeveDirektifi 2. Grup’ta İyi Çevre Statüsü’nün bir tanımlayıcısı olarak da kullanılmaktadır.

Circulating hemocytes of ark clam, Anadara kagoshimensis, were investigated using light microscopy and flow cytometry. Hemolymph contained 3 morphotype of cells, amebocytes, erythrocytes and intermediate type cells, which formed two distinct subpopulations on flow cytometric dot plots. Large cells (intermediate morphotype and erythrocytes) amounted 85.6 ± 2.8% total cells in hemolymph. Erythrocytes were hemoglobin-containing cells with up to 40 granules presented in the cytoplasm. All hemocyte types, observed in the ark clam hemolymph demonstrated equal capacity to spontaneous production of reactive oxygen species.

В работе дано описание состояния промыслового скопления анадары Броутона Амурского залива порезультатам мониторинга 2018 г. Суммарная численность моллюсков в скоплении на площади 136,94 км2 составляет около 62 млн экз. Общий запас насчитывает 11,6 тыс. т, промысловый – 9,1 тыс. т. Эксплуатируемая часть скопления находится на уровне 6,2 тыс. т. Состояние скоплений оценено как относительно стабильное., The description of commercial aggregation of the Ark clam in the Amur Bay based on the study conducted in 2018 is given. The total number of mollusks in the aggregation on the area of 136,94 km2 amount about 62 million individuals. The total clam stock is estimated 11,6 thousand tons, and the commercial stock is 9,1 thousand tons. The harvested amount of the aggregation is at level of 6,2 thousand tons. Stock condition is considered as relatively stable.

Parameters of the antioxidant system as well as carbohydrate, protein, and energy metabolisms in the tissues of an invader species, the bivalve mollusk Anadara kagoshimensis, are compared. Tissue specificity of the examined parameters is demonstrated. Along with the hepatopancreas and gills, the foot of anadara is shown to be an important metabolic organ with a high metabolism and an antioxidant defense. The content of low molecular weight biological antioxidants and antioxidant enzyme activities are specifically balanced in the examined mollusk tissues. The behavioral, physiological, and biochemical features that have provided successful invasion of this mollusk in the Black Sea–Azov basin are discussed.

In the present study, we report the whole genome sequences of two species, Ornithinibacillus contaminans DSM22953(T) isolated from human blood and Ornithinibacillus californiensis DSM 16628(T) isolated from marine sediment, in genus Ornithinibacillus. Comparative genomic study of the two species was conducted together with their close relative Ornithinibacillus scapharcae TW25(T), a putative pathogenic bacteria isolated from dead ark clam. The comparisons showed O. contaminans DSM22953(T) had the smallest genome size of the three species indicating that it has a relatively more stable habitat. More stress response and heavy metal resistance genes were found in the genome of O. californiensis DSM 16628(T) reflecting its adaption to the complex marine environment. O. scapharcae TW25(T) contained more antibiotic resistance genes and virus factors in the genome than the other two species, which revealed its pathogen potential.

Chitosan of ark clams shell is regarded as untapped waste; it has potential as a heavy metal chelating agent and anti-bacterial. The objective of this research is to examine the effect of chitosan of the ark clams shell as a chelating agent to decrease of Pb and Hg level in the blood cockles meatball. This research is also aimed at exploring the capability of chitosan of the shell in decreasing the bacteria within blood cockle meatball. This research conducted complete randomized design with the provision of five-level of chitosan concentration, i.e., 0%, 0.5%, 1%, 1.5%, 2.0%. Atomic-Absorbent Spectrophotometric (AAS) method used to examine the level of Pb and Hg within the meatball, while the total of bacteria was determined by using Total Plate Count (TPC) method. The data were analyzed by using Analysis of Variance (ANOVA) and Least Significant Difference (LSD) test. The results reveal that the administration of chitosan of ark clam on blood cockle meatballs reduced Pb levels from 0.195 ppm to 0.168 ppm, while Hg levels reduced from levels of 0.018 to 0.008 ppm, and the number of bacteria from 2.4 × 102 to 1.4 × 102 colony/g. In conclusion, the chitosan of the ark clams shell can ensure the safety of the meatball product.

The marine bacterium Neptunomonas concharum was firstly characterized in 2012. It preferred to utilize acetate as the carbon source to accumulate poly-3-hydroxybutyrate (PHB) as intracellular carbon and energy storage. Here we report the genomic characteristics of N. concharum JCM17730T. The complete genome sequence of N. concharum JCM17730T consists of 3,561,992 bp in one contig, without plasmid. Analysis of coding sequences revealed the presence of genomic features involved in acetate assimilation and PHB metabolism. The genome of N. concharum JCM17730T contains three genes encoding acetyl-CoA synthetase and two genes encoding isocitrate lyase. Three polyhydroxyalkanoate synthases and one polyhydroxyalkanoate depolymerase are scattered throughout the genomic DNA. The genome features provide interesting insights into the acetate and PHB metabolism of N. concharum JCM17730T and would facilitate further research on the genetic engineering of marine bacteria for efficient PHB production.

OsHV-1 is an epidemic pathogen of molluscs, and temperature has been recognized as a decisive environmental factor in its pathogenicity. In recent years, ark clam, Scapharca broughtonii, emerged as a host for OsHV-1. In the north of China, massive summer mortalities of ark clams infected with OsHV-1 have been continuously reported since 2012. However, the interaction between temperature and the pathogenicity of OsHV-1 was unknown in ark clams. In this study, the effect of temperature (10 °C to 18 °C stepped by 2 °C) on the occurrence of OsHV-1 disease in ark clams was analyzed. OsHV-1 infection led to gill erosion but not below the critical low temperature (between 12 °C and 14 °C). However, OsHV-1 persisted for more than 2 weeks at 12 °C post inoculation and replication was reactivated when the temperature was elevated to 18 °C. No significant reduction of OsHV-1 DNA load was found when the temperature descended to 12 °C from 18 °C, while the gill erosion remained unchanged. Ark clams failed to show the capability of effective clearance of OsHV-1 below the critical low temperature. Our results demonstrated that the pathogenicity of OsHV-1 was influenced significantly by temperature. Moreover, high temperature favored infection, which could provide more information to understand summer mortality of ark clams.

High levels of ostreid herpesvirus 1 (OsHV-1) were detected in hemocytes of OsHV-1 infected mollusks. Mollusk hemocytes are comprised of different cell types with morphological and functional heterogeneity. Granular cells are considered the main immunocompetent hemocytes. This study aimed to ascertain if OsHV-1 infects specific types of hemocytes in ark clams. Types of hemocytes were first characterized through microexamination and flow cytometry. In addition to a large group of red cells, there were three types of recognizable granular cells in ark clams. Type II granular cells were mostly found with OsHV-1 infection by transmission electron microscope (TEM) examination, and represented the hemocyte type that was susceptible to OsHV-1 infection. The subcellular location of OsHV-1 particles in apoptotic type II granular cells was further analyzed. Some OsHV-1 particles were free inside the apoptotic cells, which may contribute to OsHV-1 transmission among cells in the host, some particles were also found enclosed inside apoptotic bodies. Apoptosis is an important part of the host defense system, but might also be hijacked by OsHV-1 as a strategy to escape host immune attack. Following this investigation, a primary culture of type II granular cells with OsHV-1 infection would facilitate the research on the interaction between OsHV-1 and mollusk hosts.

Morphological analysis, molecular characterization, and information on distribution and density of Anadara kagoshimensis (Tokunaga, 1906) specimens collected in the Adriatic Sea were here carried out as based on various material and data from five surveys conducted from 2010 to 2014, for a total of 329 bottom trawl hauls. The morphological and molecular analyses allowed to clarify the confused taxonomy regarding the biggest ark clam alien species invading the Italian waters and the Mediterranean Sea. The analysis on distribution and density revealed that A. kagoshimensis mostly occurs along the Italian coast at depths from 8 to 50 m, with a catch frequency of more than 98% in all hauls performed on silty-clay sediment at 8-30 m depth. The hotspot map clearly shows a reduction of its distribution area from 2010 to 2012.

Ostreid herpesvirus-1 (OsHV-1) presents interspecies transmission among bivalves. Recently, events of mass mortalities of ark clams (Scapharca broughtonii) infected with OsHV-1 have been recorded. To accurately assess the gene responding patterns of ark clams post OsHV-1 infection, constant stable housekeeping genes (HKGs) are needed as internal control to normalize raw mRNA expression data. In this study, ten candidate HKGs were selected, including 18S rRNA (18S), beta-actin (ACT), Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), NADH dehydrogenase subunit (NADH), Elongation factor-1a (EF-1a), Elongation factor-1β (EF-1β), Elongation factor-1γ (EF-1γ), Ribosomal protein L7 (RL7), Ribosomal protein L15 (RL15) and Ribosomal protein S18 (S18). The expression levels of ten candidate HKGs were analyzed by real-time PCR under given experimental conditions, including various tissues, OsHV-1 challenge, temperature stress and OsHV-1 challenge at different temperature. Their expression stability values were further calculated using two different statistical models (geNorm and NormFinder). The results showed that different tissues presented distinct best pair genes combinations for gene expression analysis under OsHV-1 challenge. RL15 was comparatively more stable than other HKGs under various experimental conditions, while commonly used 18s and ACT seemed to be more greatly influenced by most given experimental conditions in ark clams. This study emphasized the necessity of prior validation of HKGs and would facilitate future gene expression analysis in ark clams or other shellfishes.

none 11 no Morphological analysis, molecular characterization, and a study of the distribution and density of Anadara kagoshimensis (Tokunaga, 1906) specimens collected in the Adriatic Sea were carried out using materials and data collected in the course of 329 bottom trawl hauls conducted in ve yearly surveys, from 2010 to 2014. Morphological and molecular analysis allowed clarifying the confused taxonomy of the largest alien ark clam species invading Italian waters and the Mediterranean Sea. Analysis of the distribution and density data demonstrated that, along the Italian coast, A. kagoshimensis is mostly found at depths of 8 to 50 m, with a catch frequency of more than 98% in the hauls involving silty-clay sediment at a depth of 8-30 m. The hotspot map clearly shows a reduction in the distribution area of the species from 2010 to 2012. Strafella, P.; Ferrari, A.; Fabi, G.; Salvalaggio, V.; Punzo, E.; Cuicchi, C.; Santelli, A.; Cariani, A.; Tinti, F.; Tassetti, A.; Scarcella, G. Strafella, P.; Ferrari, A.; Fabi, G.; Salvalaggio, V.; Punzo, E.; Cuicchi, C.; Santelli, A.; Cariani, A.; Tinti, F.; Tassetti, A.; Scarcella, G.

Barbatia decussata is a member of intertidal communities occurring at rocky shores in the northern Persian Gulf. Population dynamic for this clam was explored from August 2011 to September 2012 on rocky intertidal shores in the northern Persian Gulf. The results showed that the Ark clam mostly occurred in the middle followed by lower intertidal zones and its distribution was associated with substrate morphology mostly occurring on shaded sides of boulders and cobbles followed by in crevices. Total shell length (SL) for 7064 individuals of Ark clams ranged from 2.21 to 53.93 mm. The growth parameters for the von Bertalanffy function were L∞ = 57.75 mm, K = 0.47 year− 1, and t0 = − 0.29 year. The growth performance index (Φ′), longevity, asymptotic weight (W∞), and natural mortality were 3.2, 6.29 years, 40.38 g, and 1.79 year− 1, respectively. The exponent “b” value was 3.181 indicating that this clam bears a positive allometric growth pattern. The recruitment pattern was continuous with two major peaks. T...

Mass mortality of ark clam, Scapharca broughtonii, occurred in a local farm along the Bohai Sea, China in August 2017. Ostreid herpesvirus SB strain, which was the only pathogen previously reported in S. broughtonii, was not detected in moribund S. broughtonii. However, four kinds of bacteria were isolated from the hepatopancreas of naturally diseased S. broughtonii, and they were further identified based on 16S rDNA gene sequence analysis. These bacteria were closely related to Vibrio harveyi (A2-1), Microbulbifer variabilis (A2-2), V. alginolyticus (A2-3), and Pseudoalteromonas sp. (A2-4). Hemolysis test showed that A2-1 exhibited a strong hemolytic activity. The cumulative mortality of S. broughtonii with foot-injected A2-1 reached 100%, which was significantly higher than that of groups infected with other bacteria. Notably, temperature showed a significant effect on the mortality of S. broughtonii infected with A2-1, as the immersion challenged test showed 100% mortality occurred at 25 ± 2 °C on the 9th day, whereas no death was observed at 15 ± 2 °C on the 12th day. Temperature also significantly affected the growth rate and extracellular protein secretion of A2-1. In conclusion, this study is the first to report that V. harveyi is a pathogen that causes mass mortality in S. broughtonii, and the temperature is an important environmental factor that affects the virulence of A2–1 on S. broughtonii.

Ark clams (Anadaraspp.) are one of the potential fishery resources off the East Coast of Surabaya. The purpose of this research was to determine the condition and stock status of Anadara spp. The biomass dynamic model was the method used to obtain the stock status of this species. For the estimation of biomass, starting in 1960, it continued to increase until finally it stabilized. Starting in the 2000s, the condition of the ark clam biomass began to decline. For the limit reference point (LRP), the value is expected to be about 7,215.55 tons with a catch effort (fmsy) of 334 units and with the Bmsy being 6,7121,38 ton; this includes MSY. For the condition of the stock in 2016, the catch was 1,2957 ton and the effort was 445 units. This means that the actual stock of the ark clam (Anadara spp.) off the East Coast of Surabaya exceeds the MSY, fmsy, and Bmsy. This is an indication of overfishing in the coastal area.

A Gram-negative, motile, facultatively anaerobic rod, designated A36T, was isolated from a dead ark clam found on the south coast of Korea. The isolate was catalase- and oxidase-negative. 16S rRNA gene sequence analysis indicated that strain A36T was most closely related to Kistimonas asteriae KMD 001T, with which it shared 98.2 % 16S rRNA gene sequence similarity. Strain A36T grew optimally at 30–37 °C, with 1 % (w/v) NaCl and at pH 8.0. The major respiratory quinone was ubiquinone-9 (Q-9). The major polar lipids were phosphatidylserine, phosphoethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were summed feature 3 (comprising C16 : 1ω7c and/or iso-C15 2-OH) and C16 : 0. The genomic DNA G+C content was 47.3 mol%. DNA–DNA relatedness between the isolate and K. asteriae JCM 15607T was T represents a novel species of the genus Kistimonas , for which the name Kistimonas scapharcae sp. nov. is proposed. The type strain is A36T ( = KACC 16204T = JCM 17805T). An emended description of the genus Kistimonas is also provided.

A novel Gram-staining-negative, facultatively anaerobic, motile and rod-shaped bacterium, designated strain LHW37T, was isolated from a dead ark clam collected on the south coast of Korea. The novel strain grew optimally at 37 °C, at pH 7.0–8.0 and with 2 % (w/v) NaCl. The predominant cellular fatty acids were C18 : 1ω7c and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The major isoprenoid quinone was ubiquinone-8 (Q-8) and the predominant polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strain was most closely related to Neptunomonas japonica JAMM 0745T (97.1 % sequence similarity). The genomic DNA G+C content of strain LHW37T was 48.2 mol%. The DNA–DNA relatedness values recorded in hybridization experiments between the novel strain and its closest known relative were ≤18 %. Based on the phenotypic, genotypic and phylogenetic data, strain LHW37T represents a novel species belonging to the genus Neptunomonas for which the name Neptunomonas concharum sp. nov. is proposed. The type strain is LHW37T ( = KACC 15543T = JCM 17730T). An emended description of the genus Neptunomonas is also provided.

A novel Gram-negative, obligately aerobic, non-motile, rod-shaped bacterium, strain M97T, was isolated from marine sediment of a cage-cultured ark clam farm on the south coast of Korea. Strain M97T was positive for oxidase and catalase. Optimal growth occurred at 37 °C, with 1–2 % (w/v) NaCl and at pH 7–8. The main cellular fatty acids were C16 : 0, C18 : 1ω7c, C12 : 0 3-OH and cyclo-C19 : 0ω8c. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unknown aminolipid and three unknown lipids. The predominant respiratory quinone was ubiquinone-10 (Q-10). Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain M97T belongs to the genus Tropicimonas , with highest sequence similarity to Tropicimonas aquimaris DPG-21T (99.0 %). The DNA G+C content of strain M97T was 68.5 mol%. Mean DNA–DNA relatedness between strain M97T and T. aquimaris DPG-21T was 46±10 %. Based on phylogenetic, phenotypic and genotypic analyses, strain M97T is considered to represent a novel species of the genus Tropicimonas , for which the name Tropicimonas sediminicola sp. nov. is proposed. The type strain is M97T ( = KACC 15544T = JCM 17731T).

In order to study PAHs concentration in Ark clam Barbatia helblingii, in Bushehr coastal zone, samples of clams was collected from five stations. Following digestion of clam's soft tissues in methanol, their PAHs content was extracted with hexane solvent and then measured by HPLC. Result showed that the total PAHs concentration in samples taken from Rafael, Sheghab, Abshirinkon, Lian and Helyleh were 634.7, 476.7, 129.5, 452.5 and 415.0 ng g-1(dw) respectively. Significant difference was observed between tPAHs concentration in different stations (P

A novel Gram-negative, motile, and ovoid-shaped strain, LHWP3(T), which belonged to the family Planctomycetaceae in the phylum Planctomycetes, was isolated from a dead ark clam Scapharca broughtonii collected during a mass mortality event on the south coast of Korea. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the isolate was most closely related to the type strain of Rhodopirellula baltica, with a shared 16S rRNA gene sequence similarity of 94.8%. The isolate grew optimally at 30°C in 4-6% (w/v) NaCl, and at pH 7. The major isoprenoid quinone was menaquinone-6 (MK-6). The dominant polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, and unidentified polar lipids. The predominant cellular fatty acids were C16:0, C18:1 ω9c, and C18:0. The genomic DNA G+C content of strain LHWP3(T) was 53.0 mol%. Based on polyphasic taxonomic analyses, strain LHWP3(T) should be classified as a novel species in the genus Rhodopirellula in the family Planctomycetaceae, for which the name Rhodopirellula rosea sp. nov. is proposed. The type strain is LHWP3(T) (=KACC 15560(T) =JCM 17759(T)).

Strain LHWP2T, a novel, aerobic, budding, motile and ovoid bacterium belonging to the phylumPlanctomycetes, was isolated from a dead ark clam (Scapharca broughtonii) from the south coast of Korea. Strain LHWP2Tgrew optimally at 30 °C, in the presence of 4 % (w/v) NaCl, and at pH 7. The predominant cellular fatty acids were C16 : 0, C18 : 1ω7cand/or C18 : 1ω6c(summed feature 8) and C18 : 1ω9c. The major isoprenoid quinone was menaquinone-6 (MK-6). The dominant polar lipid was identified as phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strain was most closely related toBlastopirellula marinaDSM 3645T, with a 16S rRNA gene sequence similarity of 94.1 %. The genomic DNA G+C content of strain LHWP2Twas 49.5 mol%. Strain LHWP2Twas distinguished fromB. marinaDSM 3645Tbased on its optimum salinity, acid production from substrates, assimilation of substrates and DNA G+C content. Overall, these phenotypic, genotypic and phylogenetic data suggest that strain LHWP2Tshould be classified as a novel species belonging to the genusBlastopirellula, for which the nameBlastopirellula cremeasp. nov. is proposed. The type strain is LHWP2T( = KACC 15559T = JCM 17758T).

A slightly halophilic, Gram-negative, strictly aerobic, non-motile rod, designated TW15T, was isolated from an ark clam in South Korea. Growth occurred at 10–37 °C, with 1–5 % (w/v) NaCl and at pH 7.0–10.0. Optimal growth occurred at 25–30 °C, with 2 % (w/v) NaCl and at pH 8.0. Strain TW15T exhibited both oxidase and catalase activities. The major fatty acids of strain TW15T were summed feature 8 (consisting of C18 : 1ω7c and/or C18 : 1ω6c) and 11-methyl C18 : 1ω7c. The predominant isoprenoid quinone was ubiquinone-10 (Q-10). The polar lipids of strain TW15T comprised phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid, an unidentified aminolipid and five unidentified lipids. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain TW15T was most closely related to Ruegeria lacuscaerulensis DSM 11314T (98.0 % 16S rRNA gene sequence similarity). DNA–DNA relatedness with closely related strains was T represents a novel species of the genus Ruegeria , for which the name Ruegeria conchae sp. nov. is proposed. The type strain is TW15T ( = KACC 15115T = JCM 17315T).

A novel Gram-positive, aerobic, motile, hemolytic, endospore-forming and rod-shaped bacterium TW25(T) was isolated from a dead ark clam during a mass mortality event on the South coast of Korea. The strain grew optimally at 30°C, at pH 8-9, and with 1% (w/v) NaCl. The 16S rRNA gene sequence analysis indicated that strain TW25(T) was associated with the genus Ornithinibacillus and that it was most closely related to the type strain of Ornithinibacillus californiensis (98.5% similarity). The dominant cellular fatty acids were iso-C15:0, anteiso-C15:0 and C16:0. The peptidoglycan amino acid type was A4β, containing L: -ornithine and D: -aspartic acid. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, four unidentified phospholipids, two unidentified aminolipids and two unidentified lipids. The major respiratory quinone was menaquinone-7 (MK-7). The G + C content of genomic DNA was 36.7 mol%. DNA-DNA hybridization experiments with related strains revealed lower than 11 ± 3% relatedness. Based on this polyphasic taxonomic study, strain TW25(T) represents a novel species in the genus Ornithinibacillus, for which the name Ornithinibacillus scapharcae sp. nov. is proposed. The type strain is TW25(T) (=KACC 15116(T) = JCM 17314(T)).

Ornithinibacillus sp. strain TW25, belonging to the family Bacillaceae , was isolated from a dead ark clam during a mass mortality event. Here, the draft genome sequence of strain TW25 (3,843,870 bp, with a G+C content of 36.7%) is reported. This is the first Ornithinibacillus genome to be sequenced.

Heavy metal pollution is known to be widespread in the sediments of the Lagoon of Venice. Therefore, physiological parameters influenced by this form of contamination were examined. The bivalve molluscs blue mussel (Mytilus galloprovincialis), ark clam (Scapharca inaequivalvis), and Japanese littleneck (Tapes philippinarum) were sampled in two sites (Marghera, Chioggia) every 3 months for 1 year. The digestive gland and gills of each bivalve were analyzed. The concentrations of essential and nonessential metals (including chromium, manganese, iron, cobalt, nickel, copper, zinc, and cadmium) were determined. Because glutathione and metallothioneins (MTs) are involved in metal homeostasis and detoxification, their concentrations were evaluated in relation to metal concentrations. Results show that (1) all three studied species accumulate metals to a considerable extent, with some species-specific differences between the digestive gland and gills; (2) gills are a good tissue to evaluate pollution by examining the MT content. In particular, the correlation between Zn and MT levels in the gills indicates that M. galloprovincialis and S. inaequivalvis are sentinel organisms and can be used specifically for Zn pollution; (3) T. philippinarum accumulates Cu in the digestive gland more readily than the other two bivalves and therefore has the highest MT.

Ruegeria sp. TW15, which belongs to the family Rhodobacteraceae , was isolated from an ark clam in the South Sea of Korea. Here is presented the draft genome sequence of Ruegeria sp. TW15 (4,490,771 bp with a G+C content of 55.7%), a member of the marine Roseobacter clade, which comprises up to 20% of the bacterioplankton in the coastal and oceanic mixed layer.

1. 1. Heart rates in N. ponderosa decrease slowly as the p O 2 declines from 159 to 4 torr. 2. 2. Neither the flow rate nor the periods of ventilation change over a broad range of water p O 2 . 3. 3. Blood p O 2 declines when water p O 2 is reduced, but the change in hemoglobin oxygenation and thus the volume of O 2 carried in the blood remains stable. 4. 4. The bradycardia and the increased transport function of the hemoglobin explain the observed constancy of O 2 extraction at reduced water p O 2 .

Cercaria anadarae sp. n., a cytophorous cercaria of a digenetic trematode of the superfamily Hemiuroidea, was found developing in the nephridia of 39 to 356 specimens of Anadara brasiliana (Lamarck), the incongruous ark clam, collected from the beachfront in the vicinity of Galveston, Texas. The germinal sacs containing cercariae were found to leave the host clam before liberation of cercariae when infected clams were isolated in bowls of seawater. This is the first record of a hemiuroid larva from a bivalve host, all previous hemiuroids having been reported from gastropod molluscs. The Hemiuroidea (Trematoda: Digenea) are the only flukes known to produce cystophorous cercariae, and in all of the approximately 40 known species, the cercariae develop in rediae in gastropod and scaphopod molluscs (Dollfus, 1950). In most known hemiurid life cycles the cercariae are planktonic and are ingested by copepods, and the adults are found in the digestive tract of carnivorous fishes (Schell, 1970). During a survey of the helminth parasites of marine molluscs of the Galveston Bay area, Texas (Wardle, 1974), a cystophorous cercaria was found in Anadara brasiliana (Lamarck) which inhabits the sandy substrates in and beyond the shallow surf zone along the Gulf of Mexico side of Galveston Island, Texas. During the winter months, combinations of strong winds and low tides agitate the substrate and the clams are washed from their shallow sand burrows and deposited on the strand line of the beach where they were hand-collected. Two species of larval flukes were found in this clam, one a bucephalid from the gonadal area and the other a member of the Hemiuroidea which was unusual in that the host mollusc is a bivalve rather than a scaphopod or gastropod which is the usual host. The cercaria is named after the generic name of the host clam. Since many more adult hemiuroid flukes than larvae have been reported from the northwest Gulf of Mexico, and since the host and its infection are quite common, it is likely that the adult will prove to be a previously described species from one of the common coastal fishes. Measurements are in micrometers unless otherwise noted. Cercaria anadarae sp. n. (Figs. 1, 2) Diagnosis: Cystophorous cercaria (Fig. 1), body 72 to 110, elongate, pyriform, tail cyst spherical, 54 to 65 in diameter, bearing 2 latitudinal rows of 8 to 9 long curved setae each. Center of cysts bearing sac housing 9-segmented protrusile delivery tube 50 long when extended by coverslip pressure. Normally, the tube is withdrawn into the cyst. Mouth and oral sucker indistinct. Pharynx and intestine apparently lacking, body densely packed with parenchyma and with a network of larger nucleated cells connected by fibrils forming a meshwork pattern. Excretory bladder inverted pyriform, size variable in live specimens 12 to 20 long by 15 wide, not visible in preserved specimens. Excretory pore posterior and terminal. Common collecting tubules entering bladder on anterior margin. Four flame cells observed on each side of body. Further details of excretory system not observed. Body cuticula thick and aspinose. Cercariae developing in germinal sacs (Fig. 2) located in nephridia of host clam. Germinal sacs pale orange in color, very mobile, elongate, 1.3 to 4.8 mm in length by 0.30 mm wide with conical anterior end bearing birthpore, and containing hundreds of cercariae. Germinal sac appearing externally segmented due to anterior muscular annulations approximately 100 apart. Host: Anadara brasiliana (Lamarck), incongruous ark clam. Locality: Galveston Beach, Texas. Prevalence: Thirty-nine of 358 clams (10.8%).