Survey of the genetic variability of populations of <i>Ruditapes philippinarum</i> from tre Gulf of Olbia (N-E Sardinia) by microsatellites = Indagine sulla variabilità genetica di popolazioni di <i>Ruditapes philippinarum</i> provenienti dal golfo di Olbia (N-E Sardegna)

Genetic variability was investigated at six microsatellite loci of the Manila clam Ruditapes philippinarum (Adams &amp; Reeve, 1850) (Bivalvia) from the Gulf of Olbia (N-E Sardinia) and Sacca di Goro (N Adriatic Sea). We found no significant differentiation among Sardinian samples and between those and the Adriatic one, which suggests the absence of a founder effect in Sardinian population

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

Age and growth of a highly successful invasive species: the Manila clam Ruditapes philippinarum (Adams & Reeve, 1850) in the Tagus Estuary (Portugal)

The Manila clam Ruditapes philippinarum (Adams & Reeve, 1850) was introduced in several regions worldwide where it is permanently established. In Portuguese waters, the colonisation of the Tagus Estuary by this invasive species coincided with a significant decrease in abundance of the native Ruditapes decussatus (Linnaeus, 1758). This study aimed to estimate the age and growth of the Manila clam, to compare the growth performance between R. philippinarum and R. decussatus in several locations worldwide, and to ascertain whether the Manila clam's growth patterns contributed to the extensive distribution of this invasive bivalve in the Tagus Estuary. The growth of R. philippinarum in the Tagus Estuary was described through the von Bertalanffy equation SLt=65.2[1-e(-0.34(t+0.93))],corresponding to a phi-prime index (phi') of 3.160 and an overall growth performance of 4.974. This growth performance is the second highest recorded for R. philippinarum worldwide and was much higher than that of R. decussatus from Portugal. This study confirmed that the Tagus Estuary presents near-ideal environmental conditions for growth of the Manila clam. R. philippinarum displayed clearly invasive behaviour, spreading widely and growing faster than the native R. decussatus, which certainly contributed to the decline of its populations in the Tagus Estuary.Fundacao para a Ciencia e Tecnologia (FCT Portugal) [SFRH/BPD/26348/2006]; project "Ameijoajaponesa - estado actual da populacao do estuario do Tejo, impactos e gestao da apanha"; Fisheries Operational Programme (PROMAR); European Fisheries Fund (EFF); strategic plan of MARE - Marine and Environmental Sciences Centre [UID/MAR/04292/2013]; FCT [UID/Multi/04326/2013

Brown muscle disease and Manila clam Ruditapes Philippinarum dynamics in Arcachon Bay, France

Brown Muscle Disease (BMD) affects Manila clam Ruditapes philippinarum. It was described for the first time in 2005 in Arcachon Bay, France. The pathology consists in a progressive necrosis of the posterior adductor muscle, valve gaping, clam migration to the sediment surface, and death. This study aims to quantify the prevalence of BMD in the bay and to evaluate the effect of BMD on Manila clam dynamics. The prevalence was assessed on 50 stations spread within Arcachon Bay. About 62% of Manila clam habitat surface was infected by BMD. A survey of buried and surface clams was conducted from November 2006 to March 2008 in Lanton, a site infected by BMD. Modal progression analysis separated confidently cohorts from 2003 to 2005 recruitments. This pathology only affected adult clams (&gt;25 mm, &gt;2 years). For both buried and surface individuals, shell length was significantly correlated with BMD infection. Surface clams had prevalence (67%) higher than buried clams (23%) and showed greater mortality rate after 15 d in running water: 82% against 12% for buried individuals. The final disease index (FDI) and the condition index (CI) were monthly evaluated on 50 clams located at each position in the sediment. CI displayed a significant decrease after BMD's infection from light to severe disease stages. Length data analysis through Bhattacharya's method (FISAT II software) allowed identifying four cohorts. The 2003s cohort enabled to calculate mortality rate that was 39% for 5 months and to estimate that BMD was responsible of 95% of that mortality. The temperature was certainly an important factor in BMD transmission, because cohort dynamics results argued that BMD developed during spring and summer

Effects of environmental and biological factors on the recruitment and growth of the Manila clam Ruditapes philippinarum in the intertidal zone, Taean, west coast of Korea

조간대에서 우점하는 바지락의 분포는 환경 요인과 생물 요인들의 영향을 받지만, 두 요인을 포함한 상호관계 연구는 매우 제한적이다. 본 연구에서는 바지락이 우점하는 조간대에서 바지락의 개체군 변동에 영향을 주는 환경 요인과 생물 요인을 분석하였고, 또한 이 요인들이 대형저서동물 군집에 미치는 영향을 알아보았다. 조사지역은 태안 의항리와 파도리 조간대로 2013년 8월부터 2015년 1월까지 매월 방형구 (0.25 m2) 를 이용하여 1mm 이상 크기의 저서동물을 채집하였고 바지락의 개체군 분석을 위해 채형변수를 측정하였다. 태안 근소만 조간대에서는 2011년 4월부터 2014년 12월까지 계절별로 한 개 정점에서 저서동물을 채집하여 군집구조를 분석하였다. 의항리와 파도리의 수온은 각각 평균 13.9 °C와 14.8 °C로 나타났고, 염분은 평균 29.8, 29.9 로 나타나 차이가 없었다. 퇴적물의 평균입도의 경우 의항리가 4.31 Φ로 3.15 Φ인 파도리보다 높았으며 통계적으로 유의한 차이를 보였다. 클로로필 a는 수층과 퇴적물 모두 평균적으로는 파도리가 높았지만 통계적으로 차이를 보이진 않았다. 바지락 전체 서식 밀도는 파도리가 평균 325 개체/0.25m2로 평균 194 개체/0.25m2인 의항리보다 많았다. 그러나 각장 10mm 이하의 치패의 경우 의항리가 평균 132 개체/0.25m2로 평균 12 개체/0.25m2인 파도리보다 많았다. 의항리에서 바지락은 10월부터 퇴적물에 가입되어, 다음해 5월까지 지속적으로 성장하여 성체 가입이 이루어지지만, 파도리에서는 3-4월 사이에 가입된 치패는 성체로 성장하지는 못하였다. 성체의 개체수가 증가할수록 비만도는 감소하였으나, 치패의 개체수가 증가할수록 비만도는 증가하였다. 치패의 가입은 파도리보다 의항리에서 높았다. 근소만에서 대형저서동물 총 출현 종수는 146종이였고, 갯지렁이가 60종으로 가장 많이 나왔고 그 다음으로 갑각류와 연체동물이 각각 53종, 16종으로 많이 나왔다. 우점종으로는 바지락 (Ruditapes philippinarum) 이 평균 1335 개체/m2로 가장 많았으며, 그 다음으로 갯지렁인 Heteromastus filiformis, Ceratonereis erythraeensis, Ampharete arctica 순으로 우점하였다. 이 연구에서 바지락의 비만도와 성체는 퇴적물 평균 입도의 영향을 받았고, 바지락 치패의 가입은 성체의 서식 밀도에 많은 영향을 받았다. 그러므로 바지락 최적 서식환경을 유지하기 위해서는 서식지 퇴적물 환경 뿐 만 아니라 바지락 개체수의 조절이 중요할 것으로 여겨진다.Contents List of Tables ⅳ List of Figures ⅴ Abstract ⅶ Chapter 1. General intrudoction 1 1.1 Macrobenthos community in a intertidal zone 1 1.2 Environmental factors of Ruditapes philippinarum 3 1.3 General imformation of study area 4 1.4 Aims of this study 5 Chapter 2. Effects of environmental and biological factors on the recruitment and growth of Ruditapes philippinarum 6 2.1 Introduction 6 2.2 Materials and Methods 8 2.3 Results 11 2.4 Discussion 30 Chapter 3. Macrobenthos community in Ruditapes philippinarum aquaculture 37 3.1 Introduction 37 3.2 Materials and Methods 39 3.3 Results 41 3.4 Discussion 56 Chapter 4. General Discussion 59 4.1 Effects of environmental and biological conditions on the recruitment and growth of Ruditapes philippinarum 59 4.2 Macrobenthos community in Ruditapes philippinarum aquaculture 61 References 63Maste

Opadanje stoka školjkaša Ruditapes philippinarum u uvalama sjevernog Jadrana:anketa o ekološkim i društveno-ekonomskim aspektima

The Manila clam, Ruditapes philippinarum, introduced in the Venice lagoons in 1983 and rapidly spread to the nearby coastal lagoons represents one of the most important commercially- exploited resources of this area. Abundance, size-class and biomass distribution of the wild population living in the Pialassa Baiona lagoon were assessed and related to the hydrological and sediment characteristics. Despite the lagoon being affected by eutrophication, chemical and thermal pollution, the clams were harvested by about thirty professional fishermen until 2003. The commercially available stock was estimated at 36.8 10 3 kg in July 2002, 29.3 10 3 kg in April 2003, and 10.3 10 3 kg in October 2003. Stock estimations and observed mortality were in good accordance with the fishermen data. The decline of the available stock could be due to both overfishing and the extraordinary summer heat wave occurred in 2003, which may have reduced larval recruitment and increased the mortality. Overall, the juvenile recruitment appeared insufficient to annually restore the natural stock. Although the national and regional high relevance of clams market, local harvesting of wild populations appeared marginal and inadequate to support a remunerative commercial activity, due to the variability and unpredictability of the annual yield and the lack of a sustainable management based on a production chain’s approach.Školjkaš Ruditapes philippinarum, zabilježena u Venecijanskoj laguni 1983. godine gdje se brzo proširila i na obližnje obalne lagune te predstavlja jedan od najvažnijih komercijalno iskorištenih resursa ovog područja. U laguni Pialassa Baiona procjenjene su abundancija, veličina klase i raspodjela biomase prirodnih populacija u odnosu na hidrološke i sedimentne karakteristike. Unatoč tome što je laguna bila pogođena eutrofikacijom, kemijskim i toplinskim zagađenjima, oko trideset profesionalnih ribara sakupljalo je školjke do 2003. godine. Dostupne zalihe stoka komercijalnih vrsta procijenjene su na 36,8 10, 3kg u srpnju 2002. godine, zatim na 29.3 10 3kg u travnju 2003. godine i na 10,3 10 3 kg u listopadu 2003. godine. Procjene zaliha i smrtnosti bile su u skladu s podacima ribara. Pad raspoloživih zaliha mogao bi biti posljedica prekomjernog izlova i izvanrednog ljetnoga toplinskog vala koji se dogodio 2003. godine, što je utjecalo na smanjenje novačenja ličinki i povećanje smrtnosti. Sveukupno gledano novačenje juvenilnih primjeraka nije bilo dovoljno za godišnje obnavljanje prirodnih zaliha. Iako je na nacionalnoj i regionalnoj razini velika važnost tržišta školjki, lokalna berba divljih populacija jest marginalna i neadekvatna za podupiranje profitabilne komercijalne aktivnosti, zbog varijabilnosti i nepredvidljivosti godišnjeg prinosa i nedostatka održivog upravljanja temeljenog na pristupu proizvodnog lanca

Feasibility studies in relation to the IMO Ballast Water Convention

This project is aimed to develop possibilities to overcome the difficulties which arise from the implementation of the Ballast Water Convention (IMO 2004). For this purpose, three feasibility studies have been conducted: assessment of the applicability of small scale test systems; development of protocols for testing active substance residues; risk assessment of ballast water discharge

NMR-Based Metabolomic Investigations on the Differential Responses in Adductor Muscles from Two Pedigrees of Manila Clam Ruditapes philippinarum to Cadmium and Zinc

Manila clam Ruditapes philippinarum is one of the most important economic species in shellfishery in China due to its wide geographic distribution and high tolerance to environmental changes (e.g., salinity, temperature). In addition, Manila clam is a good biomonitor/bioindicator in “Mussel Watch Programs” and marine environmental toxicology. However, there are several pedigrees of R. philippinarum distributed in the marine environment in China. No attention has been paid to the biological differences between various pedigrees of Manila clams, which may introduce undesirable biological variation in toxicology studies. In this study, we applied NMR-based metabolomics to detect the biological differences in two main pedigrees (White and Zebra) of R. philippinarum and their differential responses to heavy metal exposures (Cadmium and Zinc) using adductor muscle as a target tissue to define one sensitive pedigree of R. philippinarum as biomonitor for heavy metals. Our results indicated that there were significant metabolic differences in adductor muscle tissues between White and Zebra clams, including higher levels of alanine, glutamine, hypotaurine, phosphocholine and homarine in White clam muscles and higher levels of branched chain amino acids (valine, leucine and isoleucine), succinate and 4-aminobutyrate in Zebra clam muscles, respectively. Differential metabolic responses to heavy metals between White and Zebra clams were also found. Overall, we concluded that White pedigree of clam could be a preferable bioindicator/biomonitor in marine toxicology studies and for marine heavy metals based on the relatively high sensitivity to heavy metals

Effects of multi-walled carbon nanotube materials on Ruditapes philippinarum under climate changes: the case of salinity shifts

The toxicity of carbon nanotubes (CNTs) is closely related to their physico-chemical characteristics as well as the physico-chemical parameters of the media where CNTs are dispersed. In a climate change scenario, changes in seawater salinity are becoming a topic of concern particularly in estuarine and coastal areas. Nevertheless, to our knowledge no information is available on how salinity shifts may alter the sensitivity (in terms of biochemical responses) of bivalves when exposed to different CNTs. For this reason, a laboratory experiment was performed exposing the Manila clam Ruditapes philippinarum, one of the most dominant bivalves of the estuarine and coastal lagoon environments, for 28 days to unfunctionalized multi-walled carbon nanotube MWCNTs (Nf-MWCNTs) and carboxylated MWCNTs (f-MWCNTs), maintained at control salinity (28) and low salinity 21. Concentration-dependent toxicity was demonstrated in individuals exposed to both MWCNT materials and under both salinities, generating alterations of energy reserves and metabolism, oxidative status and neurotoxicity compared to non-contaminated clams. Moreover, our results showed greater toxic impacts induced in clams exposed to f-MWCNTs compared to Nf-MWCNTs. In the present study it was also demonstrated how salinity shifts altered the toxicity of both MWCNT materials as well as the sensitivity of R. philippinarum exposed to these contaminates in terms of clam metabolism, oxidative status and neurotoxicity.publishe