KONSENTRASI MIKROPLASTIK PADA KERANG MANILA Venerupis philippinarum DI PERAIRAN MACCINI BAJI, KECAMATAN LABAKKANG, KABUPATEN PANGKAJEN KEPULAUAN, SULAWESI SELATAN

Mikroplastik di perairan menjadi permasalahan yang cukup serius bagi organisme perairan. Organisme filter feeder seperti kerang memiliki resiko yang cukup besar untuk mengakumulasi mikroplastik ke dalam tubuhnya. Salah satu jenis organisme tersebut ialah kerang manila (Venerupis philippinarum) yang banyak terdapat di Perairan Maccini Baji, Kecamatan Labakkang, Kabupaten Pangkajene Kepulauan, Sulawesi Selatan. Penelitian ini bertujuan untuk mengetahui keberadaan dan konsentrasi mikroplastik yang terdapat pada daging kerang manila (Venerupis philippinarum). Pengambilan sampel kerang dilakukan dengan metode sampling acak berlapis (stratified random sampling), sehingga diperoleh sampel sebanyak 118 ekor. 118 sampel kerang manila tersebut kemudian dibagi menjadi tiga kelompok ukuran panjang cangkang kerang yaitu kelas A (3,11 – 3,86 cm), kelas B (3,87 – 4,82 cm), kelas C (4,83 – 6,01 cm). Pengamatan partikel mikroplastik dilakukan dengan menggunakan mikroskop stereo. Hasil pengamatan menunjukkan sebanyak 61 sampel (51,69%) kerang manila mengandung partikel mikroplastik. Mikroplastik yang ditemukan berbentuk fiber dan fragmen, dengan warna dominan biru, hitam, dan transparan. Ukuran mikroplastik yang ditemukan berkisar antara 0,090 – 4,919 mm. Nilai rata-rata konsentrasi mikroplastik pada masing-masing kelompok ukuran panjang cangkang kerang secara berurutan yaitu 0,6129 item/g, 0,6303 item/g, dan 0,2198 item/g. Kata kunci: Fiber, kerang manila, konsentrasi mikroplastik, Maccini Baji, Venerupis philippinarum

The Impact of Copper on Non-Indigenous and Native Species of Suspension-Feeding Bivalves in Mission Bay, San Diego, California

Native (Chione californiensis) and non-indigenous bivalve species [Musculista senhousia (now known as Arcuatula senhousia), and Venerupis philippinarum] were collected from Mission Bay, San Diego, California and exposed to copper contaminated water at estimated concentrations of 0 ppb, 25 ppb, and 50 ppb over the course of two experimental periods of 18 days and 12 days. Bivalves were placed in tanks in a temperature controlled environment, and measurements of a number of parameters were taken during and after the exposure to copper: survivorship, feeding rates, growth, mucus production, and tissue copper concentrations for the entire body, gills, and digestive tract. These factors were analyzed on their own and in comparison to tissue copper concentration to examine potential relationships. Observations indicated that there were several statistically significant differences, either between copper concentration groups, between species, or both. The majority of sublethal measures showed no statistically significant differences across both experiments, with the exception of whole body copper accumulation. Whole body copper accumulation showed significant differences between Musculista and both Chione and Venerupis, and may suggest a competitive disadvantage in copper contaminated environments, as Chione and Venerupis may be more efficient at removing copper from tissue. Other sublethal measures that did show significance did not show consistency across both experiments or showed contradicting trends, and none showed consistently significant trends when compared with tissue copper concentrations. Algae depletion rate measurements produced inconclusive results. The data indicates that most sublethal biomarkers used in this experiment were not indicators for copper toxicity for the species in this experiment at the tested concentrations, and that of those species, Chione was the most resistant to the effects of copper with respect to mortality and whole body accumulation

Terminal-repeat retrotransposons in miniature (TRIMs) in bivalves

Terminal repeat retrotransposons in miniature (TRIMs) are small non-autonomous LTR retrotransposons consisting of two terminal direct repeats surrounding a short internal domain. The detection and characterization of these elements has been mainly limited to plants. Here we present the first finding of a TRIM element in bivalves, and among the first known in the kingdom Animalia. Class Bivalvia has high ecological and commercial importance in marine ecosystems and aquaculture, and, in recent years, an increasing number of genomic studies has addressed to these organisms. We have identified biv-TRIM in several bivalve species: Donax trunculus, Ruditapes decussatus, R. philippinarum, Venerupis corrugata, Polititapes rhomboides, Venus verrucosa, Dosinia exoleta, Glycymeris glycymeris, Cerastoderma edule, Magallana gigas, Mytilus galloprovincialis. biv-TRIM has several characteristics typical for this group of elements, exhibiting different variations. In addition to canonically structured elements, solo-TDRs and tandem repeats were detected. The presence of this element in the genome of each species is <1%. The phylogenetic analysis showed a complex clustering pattern of biv-TRIM elements, and indicates the involvement of horizontal transfer in the spreading of this elementXunta de Galicia | Ref. ED431C 2016-037Xunta de Galicia | Ref. ED481B/2018/091Ministarstvo Znanosti, Obrazovanja i Sporta | Ref. 098-0982913-275

Comparative study of gonadal development of Ruditapes philippinarum (Adams and Revé) and Ruditapes decussatus (L.) (Mollusca, Bivalvia): Influence of temperature

Laboratory experiments were used to study the influence of temperature on the reproductive behaviour of two species of clam, Ruditapes decussatus and Ruditapes philippinarum, during their adaptation to the temperature conditions of Galician coastal waters. In both species the rate of gonadal development was directly related to the increase in temperature. At 14°C the reproductive behaviour was similar, both species needing over 2 months to mature. At 18°C, the rate of gonadal development of R. philippinarum was greater than that of R. decussatus. Nevertheless, the results of this study confirm that both species have adapted perfectly to the temperature conditions of the Galician Rias, though certain differences between the reproductive behaviour of these species were detected. R. philippinarum accumulates oocytes prior to their partial or total emission, while in the case of R. decussatus gametes are liberated continuously. In the early phases of its development, the gonad of R. philippinarum is highly heterogeneous in nature, with up to 3 reproductive states being present at the same time, while in R. decussatus gonadal development is much more uniform. Another major difference concerns the phenomenon of reabsorption, common in R. philippinarum but very rare in R. decussatus. These characteristics may well result in a greater reproductive activity in R. philippinarum than in R. decussatus, and a longer reproduction period in the former. They may also represent a certain advantage for the adaptation of the foreign species (R. philippinarum) over the native species (R. decussatus) to the temperature conditions of the Galician Rias

Cultivo de almejas en criadero. Experiencias con la almeja japonesa ("Ruditapes Philippinarum" Adams&Reeve, 1850) y la almeja fina ("Ruditapes decussatus" Linnaeus

[Resumen:] La producción de almeja constituye un sector económico de elevadas posibilidades en el litoral español, especialmente en Galicia, comunidad donde está concentrada la mayor parte del cultivo de este molusco bivalvo. El presente trabajo tiene por objetivo estudiar cómo evolucionan la talla, el peso (fresco y seco) y la mortalidad de dos de los venéridos más comercializados en la comunidad gallega, la almeja japonesa (Ruditapes philippinarum Adams & Reeve, 1850) y la almeja fina (Ruditapes decussatus, Linnaeus, 1758). Ambas especies fueron cultivadas mediante dos sistemas diferentes: sistema abierto, con un aporte continuo de fitoplancton y agua, y sistema cerrado, donde se proporciona una única ración diaria de alimento. Además, se realiza el seguimiento de un cultivo larvario de R. philippinarum a fin de estimar el tiempo de aparición de cada una de las etapas que componen dicho estadio de desarrollo. Los resultados obtenidos mostraron los mayores crecimientos en la almeja fina al ser cultivada esta en sistema abierto, mientras que para la almeja japonesa dichos valores se alcanzan con el sistema cerrado. El cultivo larvario de almeja japonesa determinó el inicio de su fase de larva D al segundo día posterior a la puesta, la etapa umbonada a los 6-7 días, la larva pediveliger a partir de 17-18 días y la postlarva entre los días 24-25.[Abstract:] Clam production is an economic sector of high potential in the Spanish coast, especially in Galicia, where most of the culture of this bivalve mollusk is concentrated. The objective of this work is to study the evolution of the size, the weight (fresh and dry) and the mortality of two of the most traded venerids in the Galician community, the Manila clam (Ruditapes philippinarum Adams & Reeve, 1850) and the grooved carpet shell (Ruditapes decussatus Linnaeus, 1758). Both species were cultivated by two different systems: an open system, with a continuous supply of phytoplankton and water, and a closed system, where a single daily ration of food is provided. Moreover, a larval culture of R. philippinarum is monitored in order to estimate the time of appearance of each of the phases that make up this stage of development. The results obtained showed the highest growth in the grooved carpet shell when it is cultivated in the open system, while for the Manila clam, these values are reached with the closed system. Manila clam´s larval culture determined its beginning on the second day after laying with the D-stage, developing later the umbonate stage at 6-7 days, the pediveliger larvae from 17-18 days and postlarvas between 24-25 days.Traballo fin de mestrado (UDC.CIE). Acuicultura. Curso 2016/201

Comparative study of gonadal development of Ruditapes philippinarum (Adams and Reeve) and Ruditapes decussatus (L.) (Mollusca: Bivalvia): Influence of temperature

Laboratory experiments were used to study the influence of temperature on the reproductive behaviour of two species of clam, Ruditapes decussatus and Ruditapes philippinarum, during their adaptation to the temperature conditions of Galician coastal waters. In both species the rate of gonadal development was directly related to the increase in temperature. At 14ºC the reproductive behaviour was similar, both species needing over 2 months to mature. At 18ºC, the rate of gonadal development of R. philippinarum was greater than that of R. decussatus. Nevertheless, the results of this study confirm that both species have adapted perfectly to the temperature conditions of the Galician Rias, though certain differences between the reproductive behaviour of these species were detected. R. philippinarum accumulates oocytes prior to their partial or total emission, while in the case of R. decussatus gametes are liberated continuously. In the early phases of its development, the gonad of R. philippinarum is highly heterogeneous in nature, with up to 3 reproductive states being present at the same time, while in R. decussatus gonadal development is much more uniform. Another major difference concerns the phenomenon of reabsorption, common in R. philippinarum but very rare in R. decussatus. These characteristics may well result in a greater reproductive activity in R. philippinarum than in R. decussatus, and a longer reproduction period in the former. They may also represent a certain advantage for the adaptation of the foreign species (R. philippinarum) over the native species (R. decussatus) to the temperature conditions of the Galician Rias.Se llevaron a cabo experiencias de laboratorio para estudiar la influencia de la temperatura en el comportamiento reproductivo de dos especies de almeja, R. philippinarum y R. decussatus, en su adaptación a las condiciones térmicas en las costas de Galicia. En ambas especies la tasa de desarrollo gonadal está directamente relacionada con el incremento de temperatura. A 14ºC el comportamiento reproductivo es similar y ambas especies necesitan cerca de 2 meses para madurar. A 18ºC, la tasa de desarrollo gonadal de R. philippinarum es mayor que en R. decussatus. No obstante, los resultados de este estudio confirman que ambas especies se han adaptado perfectamente a las condiciones térmicas de las rías de Galicia, si bien, se detectan ciertas diferencias en su comportamiento reproductivo. Así, mientras R. philippinarum acumula ovocitos antes de su emisión parcial o total, en el caso e R. decussatus los gametos se liberan continuamente. En las primeras fases de su desarrollo, el aspecto de la gónada de R. philippinarum es muy heterogéneo, presentándose hasta 3 estados reproductivos simultáneamente, mientras que en R. decussatus el desarrollo gonadal es bastante más uniforme. Otra diferencia concierne al fenómeno de la reabsorción, común en R. philippinarum, pero muy raro en R. decussatus. Estas características pueden sustentar una mayor actividad reproductiva en R. philippinarum comparado con R. decussatus, y un mayor periodo reproductivo en el caso de la primera. Ello puede también representar una cierta ventaje adaptativa, de la especie foráneas (R. philippinarum) frente la especie nativa (R. decussatus), a las condiciones térmicas de las rías de Galicia

Mapping the stranger: genetic diversity of Manila clam in European coastal lagoons.

Manila clam Ruditapes philippinarum - synonym Venerupis philippinarum (Adams and Reeve, 1850) is one of the most successful marine invaders worldwide and represents almost 20% of worldwide mollusc total production. Originally distributed in the Indo-Pacific region, the species was introduced for aquaculture and fisheries in North America, Polynesia, the US Virgin Islands, as well as in Atlantic and Mediterranean coasts of Europe. Due to the commercial value of the species, population genetics and stock composition are of primary importance both in natural and invaded environments. Moreover, molecular genetics can provide valuable data in invasion biology, as, for example, the structure of the exploited populations, the origin of source populations and the routes of invasions. Furthermore, molecular data might be useful for the tracking of seafood products, as requested by the European Commission for European seafood products (see EC laws n° 178/2002, 509/2006, 510/2006 and their improvements). Despite all these considerations genetic data are lacking, especially for introduced populations, and should be urgently provided. In a framework of an European network of researchers involved in Manila clam studies, clams were collected in coastal lagoons and estuaries in both Mediterranean (Northern Adriatic Sea, Italy) and Atlantic (Spain and Portugal) coasts of Europe. Both mitochondrial and nuclear molecular markers were applied to investigate the genetic structure of populations, specifically by the direct sequencing of 16S rDNA gene fragments and by the genotyping of 7 microsatellite markers previously used in native populations. Results demonstrated the occurrence of multiple haplotypes for 16S rDNA, even if one main haplotype was identified in the European analyzed populations. However, few sequences were available in Genbank to make comparisons with native populations. Concerning the microsatellite data, the genotyping of Manila clam populations showed low genetic diversity among them, considering the Fst values, and a lack of genetic structuring when analysed by Structure software. Both these data suggest the absence of geographic differentiation among the introduced populations of Manila clam, as a result of introgression due to translocations and other human activities. The levels of genetic diversity within introduced populations were comparable to those described from native regions, suggesting that multiple introduction events and mixed source populations can counterbalance the loss of genetic diversity caused by the founder effect. However, it must be remarked that microsatellites showed a strong occurrence of null alleles when tested by Micro-checker, as previously observed in other bivalves, suggesting that the problem is differently distributed among Manila clam populations or specific loci, thus microsatellites should be carefully checked before used in extensive population studies. In the near future, population genetics and stock identification of this species on a large scale should be assessed using new powerful markers such as those obtained by NGS (Next Generation Sequencing) methods. In conclusion, this research represents the very first extensive genetic investigation on Manila clam’s European populations, defining the levels of genetic diversity that will help to inform management practices

Larval cryopreservation as new management tool for threatened clam fisheries

Cryopreservation is the only reliable method for long-term storage of biological material that guarantees genetic stability. This technique can be extremely useful for the conservation of endangered species and restock natural populations for declining species. Many factors have negatively affected the populations of high economical value shellfish in Spain and, as a result, many are declining or threatened nowadays. This study was focused on early-life stages of Venerupis corrugata, Ruditapes decussatus and Ruditapes philippinarum to develop successful protocols to enhance the conservation effort and sustainable shellfishery resources. Firstly, common cryoprotecting agents (CPAs) were tested to select the suitable permeable CPA attending to toxicity. Cryopreservation success using different combinations of CPA solutions, increasing equilibrium times and larval stages was evaluated attending to survival and shell growth at 2 days post-thawing. Older clam development stages were more tolerant to CPA toxicity, being ethylene-glycol (EG) and Propylene-glycol (PG) the least toxic CPAs. CPA solution containing EG yielded the highest post-thawing survival rate and the increase of equilibration time was not beneficial for clam larvae. Cryopreservation of trochophores yielded around 50% survivorship, whereas over 80% of cryopreserved D-larvae were able to recover after thawingEuropean Commisssion | Ref. Horizon 2020, n. 73098

Molecular Characterization of a Novel Big Defensin from Clam Venerupis philippinarum

Antimicrobial peptides (AMPs) are important mediators of the primary defense mechanism against microbial invasion. In the present study, a big defensin was identified from Venerupis philippinarum haemocytes (denoted as VpBD) by RACE and EST approaches. The VpBD cDNA contained an open reading frame (ORF) of 285 bp encoding a polypeptide of 94 amino acids. The deduce amino acid sequence of VpBD shared the common features of big defensin including disulfide array organization and helix structure, indicating that VpBD should be a new member of the big defensin family. The mRNA transcript of VpBD was up-regulated significantly during the first 24 hr after Vibrio anguillarum challenge, which was 7.4-fold increase compared to that of the control group. Then the expression decreased gradually from 24 hr to 96 hr, and the lowest expression level was detected at 96 hr post-infection, which was still 3.9-fold higher than that of control. The mature peptide of VpBD was recombined in Escherichia coli and purified for minimum inhibitory concentration (MIC) determination. The rVpBD displayed broad-spectrum inhibitory activity towards all tested bacteria with the highest activity against Staphyloccocus aureus and Pseudomonas putida. These results indicated that VpBD was involved in the host immune response against bacterial infection and might contribute to the clearance of invading bacteria