Pen Shell Research Articles

Natural hybridization between pen shell species: Pinna rudis and the critically endangered Pinna nobilis may explain parasite resistance in P. nobilis.

Recently, Pinna nobilis pen shells population in Mediterranean Sea has plummeted due to a Mass Mortality Event caused by an haplosporidian parasite. In consequence, this bivalve species has been included in the IUCN Red List as "Critically Endangered". In the current scenario, several works are in progress to protect P. nobilis from extinction, being identification of hybrids (P. nobilis x P. rudis) among survivors extremely important for the conservation of the species.Morphological characteristics and molecular analyses were used to identify putative hybrids. A total of 10 individuals of each species (P. nobilis and P. rudis) and 3 doubtful individuals were considered in this study. The putative hybrids showed shell morphology and mantle coloration intermingled exhibiting both P. nobilis and P. rudis traits. Moreover, the analyses of 1150bp of the 28S gene showed 9 diagnostic sites between P. rudis and P. nobilis, whereas hybrids showed both parental diagnostic alleles at the diagnostic loci. Regarding the multilocus genotypes from the 8 microsatellite markers, the segregation of two Pinna species was clearly detected on the PCoA plot and the 3 hybrids showed intermediate positions.This is the first study evidencing the existence of hybrids P. nobilis x P. rudis, providing molecular methodology for a proper identification of new hybrids. Further studies testing systematically all parasite-resisting isolated P. nobilis should be undertaken to determine if the resistance is resulting from introgression of P. rudis into P. nobilis genome and identifying aspects related to resistance.

Factors affecting the survival and growth of pen shell spats in suspended intermediate culture

Factors affecting the survival and growth of pen shell spats in suspended intermediate culture

Evolution of Biomineralization Genes in the Prismatic Layer of the Pen Shell Atrina pectinata.

Molluscan shells are composed of calcium carbonates, with small amounts of extracellular matrices secreted from mantle epithelial cells. Many types of shell matrix proteins (SMPs) have been identified from molluscan shells or mantle cells. The pen shell Atrina pectinata (Pinnidae) has two different shell microstructures, the nacreous and prismatic layers. Nacreous and prismatic layer-specific matrix proteins have been reported in Pteriidae bivalves, but remain unclear in Pinnidae. We performed transcriptome analysis using the mantle cells of A. pectinata to screen the candidate transcripts involved in its prismatic layer formation. We found Asprich and nine highly conserved prismatic layer-specific SMPs encoding transcript in P. fucata, P. margaritifera, and P. maxima (Tyrosinase, Chitinase, EGF-like proteins, Fibronectin, valine-rich proteins, and prismatic uncharacterized shell protein 2 [PUSP2]) using molecular phylogenetic analysis or multiple alignment. We confirmed these genes were expressed in the epithelial cells of the mantle edge (outer surface of the outer fold) and the mantle pallium. Phylogenetic character mapping of these SMPs was used to infer a possible evolutionary scenario of them in Pteriomorphia. EGF-like proteins, Fibronectin, and valine-rich proteins encoding genes each evolved in the linage leading to four Pteriomorphia (Mytilidae, Pinnidae, Ostreidae, and Pteriidae), PUSP2 evolved in the linage leading to three Pteriomorphia families (Pinnidae, Ostreidae, and Pteriidae), and chitinase was independently evolved as SMPs in Mytilidae and in other Pteriomorphia (Pinnidae, Ostreidae, and Pteriidae). Our results provide a new dataset for A. pectinata SMP annotation, and a basis for understanding the evolution of prismatic layer formation in bivalves.

Impact of Organic Micropollutants Causing Mass Mortality of the Clams (Mactra aequisulcata) Due to Charactersitic Distribution at Karachi Coast, Pakistan


 Mass mortality of bivalve clams along with some other marine fauna was observed during the month of May 2016, mainly consisting of the clams (Mactra aequisulcata) of family Veneridae surfaced over the Clifton coast. The occurrence of mass mortality of the venerid clams Mactra aequisulcata and other marine life has been studied due to the toxicity of chlorinated hydrocarbons (DDTs, HCHs, hexa chloro benzene (HCB), chlordane, dieldrin (4-chlorophenyl), methanol (TCPMOH) and heptachlor epoxide and polychlorinated biphenyls (PCBs). Significant compositional characteristics of PCBs and DDTs were found in all dead clams and other fauna including fish (Johnius carutta), crabs (Portunus pelagicus), gastropods (Babylonia spirata), bivalves (Anadara antiquata), (Mactra aequisulcata) and the pen shell (Atrina pectinata) from Karachi coast, Pakistan. Mean concentrations (ranges) of organochlorine pesticides (OCPs) in crab (Portunus pelagicus) and fish samples were 1.1 (<0.01-1.5), 0.22 (<0.01-1.1) and 0.14 (<0.01-1.3) /µg/g. Those in, bivalves (Anadara antiquata) and pen shell (Atrina pectinata), clams (Mactra aequisulcata) were 0.09 (<0.02-1.2), 0.22 (<0.02-1.3) /µg and 0.13 (<0.01-0.27), respectively. The heptachlor epoxide was found in highest concentration in clam samples (25.00 ± 30.92) µg/g, (wet weight) however, in bivalves, (2.30 µg/g, (wet weight), which were higher than those in other gastropods. Polychlorinated biphenyls (PCBs) concentrations were also measured in the same samples of gastropods (Babylonia spirata), fish (Johnius carutta), crab (Portunus pelagicus), clams (Mactra aequisulcata), bivalves (Anadara antiquata) and the pen shell (Atrina pectinata) to determine the possible cause of mass mortality. The DDT to metabolites (DDD & DDE) concentration ratios exceeded upto 1.0 in the sessile fauna that is clams (Mactra aequisulcata) and the pen shell (Atrina pectinata) from Karachi coast. These organisms also exhibited dichloro diphenyl trichloroethane (DDT) inputs, whereas dichloro diphenyl trichloroethane (DDD) was found to be in degraded component and PCBs were generally in low concentrations. The concentrations of DDTs were higher than the ERL guidelines in the coastal areas of Karachi, suggesting that there is potential of ecological risk present in the prevailing environment.
 

Epidemiology of Noble Pen Shell (Pinna nobilis L. 1758) Mass Mortality Events in Adriatic Sea Is Characterised with Rapid Spreading and Acute Disease Progression.

From May to October 2019, multiple mass mortality events (MMEs) of Pinna nobilis were observed along Croatian coastline starting from the south-east and rapidly progressing in north-western direction. Time dynamics of the MMEs closely followed general speed and direction patterns of surface sea-currents, advancing approximately 350 km in less than 3 months. Surveillance, clinical evaluation, and sample collection were performed on multiple sites with various degrees of mortality rates. Moribund P. nobilis individuals were collected and subjected to pathological, molecular, and microscopical investigation. Affected animals were positive for Mycobacterium in 70% of the individuals, and Haplosporidium pinnae was present in 58% of the cases. Observed pathological lesions were most severe where concurrent presence of both pathogens was confirmed (in 45.8% of moribund individuals). Moderate to strong lesions were observed in animals positive for Mycobacterium only (25% of cases), and lesions were absent or minor to moderate when only H. pinnae was confirmed (16% of cases). Considering the rapid and severe spread of the MMEs, the areas less exposed to major sea currents appeared to be at lower risk of pathogen transmission. Surveillance activities along the Croatian coastline identified several P. nobilis populations in such “lower risk” areas without apparent mortality or clinical symptoms. Such areas are of particular interest as source of potentially healthy individuals to support active recovery actions.

Survival and behavior patterns associated with hypoxia at different life stages of the pen shell Atrina cf. japonica

Pen shell (Atrina cf. japonica) resources have been devastated in Ariake Bay, Japan, and to facilitate the recovery of this species, there is an urgent need to fully understand the factors contributing to its high levels of mortality. Pen shells living in natural waters grow through successive life stages, and environmental factors may affect these bivalves differently at different stages. Accordingly, to elucidate the causes of mortality in natural waters, it is necessary to gain an understanding of the quantitative effects of environmental factors on bivalves at each life stage. In this study, we sought to determine the differential effects of hypoxic conditions on 1-year-old (average shell length: 93.9 mm) and 2-year-old (146.5 mm) pen shells bred under artificial conditions. We exposed shells of each age group to six different dissolved oxygen (DO) concentrations for 96 h and monitored their behavior and survival rate. Based on the survival status, we estimated the lethal DO concentrations that induced 50%, 95%, and 5% mortality (LC50, LC95, and LC5, respectively) at each age. We found that for 1-year-old shells, the LC50 values at 48, 72, and 96 h were 0.51, 0.74, and 0.84 mg/L, respectively, whereas the corresponding values for 2-year-old shells were 0.74, 1.27, and 1.80 mg/L. Furthermore, we found that for 1- and 2-year-old shells, the estimated ranges from LC95 to LC5 at 48, 72, and 96 h were 0.39–0.68, 0.62–0.88, and 0.64–1.12 mg/L, and 0.31–1.75, 0.77–2.09, and 1.29–2.53 mg/L, respectively. Under low DO concentrations (0.47 to 1.93 mg/L and 0.49 to 3.30 mg/L for 1- and 2-year-old shells, respectively), we observed pen shells with more than half of their shell length protruding above the substrate. In addition to age and body size, the 1- and 2-year-old pen shells used in the present study also differed with respect to reproductive status, with 7.6% of 1-year-old and 96.7% of 2-year-old shells considered to be fully ripe. Collectively, our observations indicate that 2-year-old pen shells are less tolerant to hypoxic conditions than are 1-year-old pen shells, and we suspect that the differences in hypoxic tolerance could be attributable to differences in the physiological status of the pen shells during gonadal development. We believe the findings of this study will make an important contribution to enhancing our understanding of the effects of hypoxia on the viability of A. cf. japonica in natural waters.

Dynamic energy budget of endemic and critically endangered bivalve Pinna nobilis: A mechanistic model for informed conservation

The noble pen shell Pinna nobilis L. is the largest, endemic, critically endangered, and protected bivalve of the Mediterranean Sea. Effective conservation and management strategies for this species highly depend on understanding how environmental change and anthropogenic pressures impact its physiology and thereby ecological function, population persistence, and survival. Dynamic Energy Budget (DEB) theory offers a valuable mechanistic modelling framework for capturing how an organism acquires and utilizes available energy for growth, maturation, development and reproduction throughout its life cycle, while accounting for environmental conditions. In this study we parameterized and compared two types of DEB models using limited literature data: a standard model that accounts for morphological metamorphosis only, and a model that through metabolic acceleration between birth and metamorphosis captures physiological changes occurring in the larval life stage. The model with metabolic acceleration performed better, successfully simulating life history traits, growth, and reproduction of P. nobilis. We used the model to predict how food availability implemented through functional response affects growth, maturation, and reproduction of the species throughout its lifespan. We found that (i) abundant food had little effect on the size at maturation, (ii) maximum fecundity at ultimate age doubled compared to typically lower food availability in the wild, (iii) puberty could not be reached below the food availability corresponding to functional response value of 0.164, and (iv) energy allocated to reproduction was positively correlated with both bivalve size and food availability. Accounting for allometric growth observed in P. nobilis did not affect the findings, prompting us to recommend that isometric growth be assumed when modelling the bivalve using DEB. The model presented here is the first full-life cycle bioenergetic model made for P. nobilis. It can be used standalone for predicting energy budget of individuals at specific environmental conditions, or as a building block for modeling populations and ecosystems under various environmental scenarios. The model can readily incorporate other environmental factors relevant to changes in physiology and energy allocation, such as oxygen and pH.

Assessment of predominant bacteria in noble pen shell (Pinna nobilis) collected in the Eastern Adriatic Sea.

Noble pen shell (Pinna nobilis) is an endemic species and the largest known bivalve in the Mediterranean Sea. By filtering large amounts of water, they maintain a high percentage of organic matter, hence playing an important role in the marine ecosystem. The ecological community of pen shells is impressive, and there are numerous microorganisms present in its soft tissues. Since this species is highly endangered due to recently described mass mortalities throughout the Mediterranean, this study was aimed at finding out more about its microbiome. In this study, we identified the predominant bacterial populations of specimens collected at three separate locations along the Eastern Adriatic coast. The predominant bacteria were isolated and 16S rRNA sequencing was performed to identify eight different bacterial genera: Aestuariibacter sp., Aliivibrio sp., Alteromonas sp., Marinobacter sp., Pseudoalteromonas sp., Rubritalea sp., Thalassospira sp. and the Vibrio splendidus clade. The identified genera are ubiquitous in the marine environment and have previously been described as both beneficial symbionts and potential pathogens in other molluscs. There was a clear difference in the predominant bacterial populations between northern and southern sampling sites, which could be linked to water temperature. These findings indicate the need for expanded sampling over a longer time period, since more exhaustive research would provide information vital to the conservation of this critically endangered species.

The Content of Low Density Lipoprotein, High Density Lipoproteins, Cholesterol on Pen Shells (Atrina Pectinata) Fish Catch in Kenjeran Surabaya

Pen Shells (A. pectinata) Is one type of a clam that is mostly consumed, Cholesterol levels included in a category high. Although the high cholesterol levels. Shells also contain levels commonly called ldl cholesterol evil . Having shells also levels of hdl, Cholesterol levels total normal in plasma adults is of 120 until 200 mg/dl. Different from its function at the time of cholesterol levels normal, the higher cholesterol levels in the blood, the greater the risk of atherosclerosis also. The purpose of this research is to get information about ldl levels , hdl and cholesterol contained in shells kampak , as well as to determine the shells kampak who most worthy for consumption. Parameter that observed in this research was ldl , hdl , cholesterol .This study using methods descriptive against the difference levels of low density lipopprotein ( ldl ) and high-density lipoproteins ( hdl ) and cholesterol in any bivalve hatchets the results of catch fishermen in kenjeran surabaya. Average levels of ldl on pen shells (A. pictinata) In the meat is 30,990 mg/100g, in the muscle is 28,329 mg/100g and in the Digestive organs is 25,225 mg/100g ; The average levels of hdl on pen shells (A. pictinata) in the meat is 96,772 mg/100g, in the muscle is 87,139 mg/100g and in the Digestive organs is 67,516 mg/100g ; average levels of cholesterol on pen shells (A. pictinata) in the meat is 165,609 mg/100g, in the muscle is 147,382 mg/100g and in the Digestive organs is 114,551 mg/100g. Levels of LDL, HDL and cholesterol Lead to results same that is the most number are located on the meat, then muscle and at least there are on an disgestive organ.

Abnormal Karyotype of Pen Shell (Atrina pectinata) During Its Early Embryonic Development in Late Breeding Season

The pen shell, Atrina pectinata, distributes globally. It is one of the most important edible bivalves in east Asian countries. However, there are multiple difficulties in rearing pen shell larvae and juveniles because of their high mortality. To understand the mechanism underlining such high mortality at the early embryonic development stage, we obtained approximately 100 million larvae during later breeding season in June, 2017, and checked a large amount of mitotic chromosomal plates of the early embryos and post-spawning gonads tissue slices of their parents. The results showed that most diploid A. pectinata embryos have 17 pairs of chromosomes (2n = 34) as their parents do. The first pair of particularly large chromosomes are heterotypic in some diploid embryos while they are homomorphic in others. The primary sex-determination chromosome type is XX/XY. A lot of triploid, pentaploid and aneuploid embryos with different numbers of the largest homomorphic or heteromorphic chromosomes were found due to the degeneration of overmatured parent gonads which hold normal karyotype. These larvae will die even though most of them may develop into the trochophore stage with 34 chromosomes. Genetic deficiency of chromosomes will cause a high rate of mortality in early embryos in late breeding season. These findings should enrich the current knowledge of juvenile pen shell aquaculture.

Extraction, characterization and antimicrobial activity of chitosan from pen shell, Pinna bicolor

Chitosan is a biopolymer discovered abundantly on earth specifically in the exoskeleton of shrimps, crabs and insects. In the present study, isolation and characterization of chitosan from the pen shell Pinna bicolor was carried out. In addition to this, the chitosan acquired from the pen shell was tested for its antibacterial activity against five bacterial strains. The FTIR analysis confirmed the presence of NH out of plane bending (872 cm−1) and C-O-C stretching (1016 cm−1) for chitosan with 59.76% degree of deacetylation. The Micro Raman showed peaks at 1658 cm−1, 1595 cm−1 and at 954 cm−1 corresponding to chitosan. The XRD was able to establish the crystallinity of the chitosan sample with a maximum peak at 29.3°. The elemental analysis of chitosan sample confirmed higher level of carbon (10.75%) when compared to other elements such as nitrogen, hydrogen and sulphur. The antimicrobial activity of extracted chitosan was evident with greater zone of inhibition against Salmonella typhi (20 mm) and least against Shigella dysenteriae. Thus, the present study unravels the properties of chitosan extracted from P. bicolor thereby paving way for its further use in the field of biomedical science and nanotechnology.

The (Im)possibility of Communicating with Other Species

The Institute for Relocation of Biodiversity (IRB) is an artistic research agency that speculates on possible multispecies futures. IRB conducts trans-disciplinary "field work" that reflects on interspecies relations, questions the intentionality of evolution and speculates on the (im)possibility of intra-and inter-species communication. Rather than showing solutions, it addresses the complexity of the systems that are at stake. It departs from both the climate crisis and the loss of biodiversity and habitat. Inspired by the scientific discourse on facilitated adaptation or managed relocation, the IRB investigates endangered species and provides them with relocation tutorials, e.g. video tutorials. The artistic process includes the selection of an endangered species (fauna, flora, microbial). Then, research of its habitat, living conditions and the mesh of relations is conducted. A relocation tutorial is produced and presented as experimental performance to the audience - being the selected animal or plant - with humans being invited to observe this scenery. The aim is to encourage relocation to a more life sustaining habitat as a poetic contribution to possible new narratives for the future of planet Earth. In the article we describe/contempate/ one performance conducted for Pinna nobilis, the great pen shell, endemic to the Mediterranean Sea and the possible effects this intervention might have on the animal.

Corrigendum: In the Wake of the Ongoing Mass Mortality Events: Co-occurrence of Mycobacterium, Haplosporidium and Other Pathogens in Pinna nobilis Collected in Italy and Spain (Mediterranean Sea)

Following the Mass Mortality Events (MMEs) of the pen shell P. nobilis in Campania region and Sicily, a survey of moribund P. nobilis specimens was also conducted in other Italian regions (Campania, Tuscany, Sardinia and Apulia) and Spain (Catalunya). Histopathological and molecular examination of 27 specimens of P. nobils revealed different types of pathogens associated with tissue lesions, morbidity and mortality. Presence of Mycobacterium, Vibrio species, Haplosporidium pinnae and Perkinsus sp. were detected, differently distributed into the areas. The Mycobacterium sp., previously reported in Campania and Sicily samples, was observed in all the analysed areas and individuals, associated to systemic inflammatory lesions. In Spain, H. pinnae was observed in 36% of cases, always associated to the Mycobacterium sp.. Molecular study using hsp65 genes and Internal Transcriber Spacer ITS support that a new species of Mycobacteria is infecting P. nobilis, close to M. triplex and belonging to the group of M. simiae complex with M. sherrisi. Presence of Perkinsus spp. resembling P. mediterraneus was observed in 2 out of 13 Italian individuals whose presence should be addressed as potential risk for shellfish aquaculture of the area. Vibrio spp. were also detected in some case. The preliminary results of this study suggest that Mycobacterium sp., Vibrio spp., H. pinnae and Perkinsus sp. cooperate to disease pathogenesis, being Mycobacterium and Haplosporidium most of the time involved. Vigilant inspection of those areas where MME is now starting, along with continuous systematic surveys, are crucial to define the spatiotemporal progress of mortality and the role of every single pathogen in the disease outcome.

An emergency situation for pen shells in the Mediterranean: The Adriatic Sea, one of the last Pinna nobilis shelters, is now affected by a mass mortality event

We identified areas with high individual densities of the pen shell, Pinna nobilis, in two areas along the Croatian Adriatic coast. The surveys carried out in 2018 and 2019 showed population densities of approximately 9 to 13 individuals/100 m2. However, in 2019 a mass mortality event (MME) causing 36% to 100% mortality of this bivalve species was observed in the surveyed Croatian bays. The parasite Haplosporidium pinnae was identified by histological and molecular methods in all affected sampled individuals, while Mycobacterium sp. and Gram negative bacilli were detected in some affected and live bivalves. This finding constitutes the first record of these pathogens affecting P. nobilis in the middle Adriatic, confirming the continuous spread of the disease.Previously, the Adriatic water body was considered to be a natural shelter against the MME caused by pathogens in pen shell populations because of its distinct ecological features. The Adriatic Sea is a semi-closed water body with the largest continental shelf in the Mediterranean Sea, and due to its geomorphology and bathymetry, it is a sea with distinct characteristics. Monitoring plans and further studies in the Adriatic bays are now a priority for mitigating the high risk of extinction and working toward the conservation of this protected species.

Trophic plasticity in the sea urchin Paracentrotus lividus, as a function of resource availability and habitat features

Factors controlling herbivory pressure are of central importance in shaping the seascape. In the Mediterranean, the sea urchin Paracentrotus lividus is considered as a keystone herbivore in seagrass meadows and macroalgal communities. Here we explored the trophic behavior of this sea urchin in a shallow seagrass habitat of Cymodocea nodosa mixed with Caulerpa prolifera and interspersed with sandy areas in Alfacs Bay, Ebro Delta (NW Mediterranean). The seasonal pseudo-indigenous bryozoan Amathia verticillata is locally very abundant, and there is also an important population of pen shells Pinna nobilis, providing hard substrate and cover, thus being a unique environment for assessing sea urchin trophic behavior. To this end, we conducted an ensemble of food preference and foraging experiments and stomach content and stable isotope analyses. Our results showed that sea urchins strongly prefer A. verticillata over other local resources, and there was also an important presence of the bryozoan in stomach contents (ca. 44%), coupled with green and decayed seagrass leaves. Stable isotope analyses revealed that over the long term, ca. 65% of the diet of P. lividus was based on decayed seagrass leaves, followed by the bryozoan and green seagrass leaves (21.7 and 13.3%, respectively). The local availability of P. nobilis provides a preferred substrate for sea urchins, which showed limited foraging movements into the surrounding seagrass beds, particularly when A. verticillata was attached to the pen shells. The apparently high contribution of animal and detrital food to P. lividus diet is unprecedented, and suggests an opportunistic feeding behavior in sea urchins in those habitats.

Fatty acid ester metabolites of gymnodimine in shellfish collected from China and in mussels (Mytilus galloprovincialis) exposed to Karenia selliformis

Marine shellfish exposed to the microalgae Karenia selliformis can accumulate gymnodimines (GYM). Shellfish samples collected from Beihai City in Guangxi Autonomous Region, and Ningde City in Fujian Province, in the South China Sea, as well as mussels Mytilus galloprovincialis fed on K. selliformis under laboratory conditions were analyzed. Gymnodimines and various fatty acid ester metabolites were detected in the clam Antigona lamellaris and pen shell Atrina pectinata, while no esters were found in the oyster Crassostrea sp. and the gastropod Batillaria zonalis despite positive detection of free GYM in both species. When present, the predominant acyl esters observed were 18:0-GYM-A and 20:1-GYM-A. Under laboratory conditions GYM-A was accumulated and metabolized to fatty acid esters in mussels exposed to K. selliformis, with 16:0-GYM-A and 20:1-GYM-A as the major variants. A novel compound with the same accurate mass as GYM-A and its 16:0 fatty acid ester were observed in the experimental mussels but was not present in the microalgal strain to which mussels were exposed. No significant differences of reactive oxygen species (ROS) levels and antioxidant enzymes were found between mussels fed on K. selliformis or GYM-free microalgae Isochrysis galbana. This suggests the accumulation of GYM and its metabolites does not significantly impact the physiological status of mussels. While it is currently not proven that GYM affects human health, risk assessments should consider the presence of GYM esters in naturally contaminated shellfish as part of exposure analysis.

Epibiotic assemblages on the pen shell Pinna rudis (Bivalvia, Pinnidae) at Matiota Beach, São Vicente Island, Cabo Verde

The rough pen shell Pinna rudis Linnaeus, 1758 (family Pinnidae), a mollusc with an Atlantic–Mediterranean distribution, is able to live in coarse sandy substrates. Considering its shell structure and ecological characteristics, P. rudis can enhance biodiversity by providing a substrate for settlement on its shell. For this reason, we compared the diversity of benthic taxa around P. rudis shells with the species diversity on P. rudis shells, at Matiota Beach, São Vicente Island, Cabo Verde. We sampled an area of 900 m2 and recorded data in situ to estimate the population size of P. rudis and the epibiotic and benthic community diversity. The average density of P. rudis estimated in the sampled area was 6.6 ind. 100 m–2 and the highest density was found at between 2 and 3 m depth, mostly in biogenic and sandy substrates. The epibiotic species diversity on P. rudis shells was significantly higher than the species diversity in the microhabitat around the shells. The P. rudis shell seems to play an important role in increasing the biodiversity of the ecosystem, with some species found only as epibionts on P. rudis.

Value Chain Analysis of Pen Shell (Baloko) in the Province of Sorsogon, Philippines

Sorsogon Bay is home to the pen shell (Atrina pectinata), locally known as Baloko. This study was designed to assess the existing value chains of pen shell and identify areas for improvement. The sites covered were the municipalities along Sorsogon Bay in the province of Sorsogon, Philippines. It employed the tracer methodology where only the processors and fisherfolks connected to the traders were selected as respondents of the study. Primary data were gathered through semi-structured questionnaires. Secondary data were used to establish a good understanding of the pen shell industry in the areas of the study. Results show that the adductor muscle or tinga is a substitute for scallops, thus, an export product. The other parts of pen shell or rambit are also of high demand. The highest volume of pen shell catch occur during October to April during the northeast monsoon (amihan) and gradually decline from May to September during the southwest monsoon (habagat) months. The value chain maps reflect the whole meat and semi-processed value chains, the two distinct marketing practices traced in the pen shell industry. The actors in the two value chains are the fisherfolks, processors, traders, and exporters. The enablers are the fisherfolks’ organization, local government unit (LGU), Bureau of Fisheries and Aquatic Resources (BFAR), City Fisheries and Aquatic Resources Management Council (CFARMC), microfinance institutions, Department of Trade and Industry (DTI), and Phil Export. There is uneven distribution of value added in both chains. More value is created and captured by the processors while the fisherfolks have negative gains. The value-added captured by the processors and traders are higher in semi-processed practice. There is the need to focus on the supply of pen shell, the effects of pollution of Sorsogon Bay, market information, technology to preserve the quality of products, industry association, and basic researches on pen shell under Sorsogon Bay condition.

Survival and growth rate of pen shell Atrina lischkeana spats of various initial sizes and densities in suspended intermediate culture

Survival and growth rate of pen shell <I>Atrina lischkeana</I> spats of various initial sizes and densities in suspended intermediate culture

Presence of Vibrio mediterranei associated to major mortality in stabled individuals of Pinna nobilis L.

A major epizootic event attributed to Haplosporidium pinnae leading to 100% mortality of Pinna nobilis L. populations along Mediterranean coastlines started in the fall of 2016. As a result, a project to rescue 221 adult individuals of the endangered pen shell, Pinna nobilis was conducted in November 2017 in the two areas of the Spanish coast where the species was still abundant and apparently free from infection by H. pinnae: Port Lligat in the Costa Brava, and the Alfacs Bay in the Ebro Delta. For biosecurity reasons, the 106 individuals from the Ebro Delta were stabled at the IRTA facilities located next to Alfacs Bay, whereas the 115 individuals from Port Lligat were stabled in different institutions throughout the Spanish territory. Initial biopsies showed that individuals from the Ebro Delta were free of the parasite, whereas most individuals from Port Lligat were already parasitized and died in the following months. Individuals at IRTA were hold in five tanks and fed ca. 4% of their dry weight with a mix of three species of phytoplankton and fine riverine sediments (13% OM). Seawater was filtered through 10, 5 and 1 μm to ensure the absence of the parasite and disinfected with UV light. No individuals died during the 4 initial months of captivity, but two died in April–May at temperatures from 17 to 19 °C. A peak of mortalities occurred during the summer months and early fall (53%) with maximums coinciding with temperatures above 25 °C. Individuals were again analyzed by PCR and histology for the presence of H. pinnae, Mycobacteria sp., and other locally important pathogens of commercial bivalves (Vibrio splendidus, V. aestuarianus and Herpesvirus OsHV-1 microVar), and therefore considered as potential pathogens of pen shells. However, with the exception of 3 individuals that were positive for Mycobacteria sp., results were all negative for the studied pathogens. Microbiological culture and isolation of bacteria from three moribund individuals, sacrificed for study purposes, showed V. mediterranei as the dominant species, and further PCR analyses confirmed the presence of the bacterium in ten deceased individuals. Overall, our results suggest the V. mediterranei is an opportunistic pathogen of stabled individuals possibly subjected to stress from captivity, and that antibiotic treatment (Florfenicol) combined with vitamins and mineral supplementation and reduction of water temperature (15 to 18 °C), can be used to mitigate (not to eradicate) the disease. Further research is needed to determine diets and stabling conditions that minimize captivity stress and prevent the emergence of the disease.