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Recreational and professional clam fishing was an important activity on the extensive intertidal zone of the western Cotentin coast (western English Channel). A variety of fishing gear was used to harvest the target species: the European clam Ruditapes decussatus (Linnaeus, 1758) and the introduced Manila clam R. philippinarum (Adams and Reeve, 1850). In this study, we studied the effect of rake harvesting during the spring tides of February-March 2014, following an experimental design with a control station and three stations impacted by rake harvesting in three sediment types: sandy, gravelly, and mixed gravelly rocky habitats. No significant sediment and macrofauna changes occurred at the three sites after rake harvesting. Nevertheless, the number of clams decreased significantly after raking on the gravelly habitat, whereas in the other two habitats, sediment transport in this high-energy hydrodynamic environment was able to transfer clams and other macrofauna species across the fishing sites, thus minimizing the effects of rake harvesting. Therefore, although the effect of rake harvesting appeared limited during winter, the regional impact (high fishing pressure along 60 km of coast) and increase of recreational fishers during summer needed to be studied in the future. [ABSTRACT FROM AUTHOR]

RoboClam is a burrowing technology inspired by Ensis directus, the Atlantic razor clam. Atlantic razor clams should only be strong enough to dig a few centimeters into the soil, yet they burrow to over 70 cm. The animal uses a clever trick to achieve this: by contracting its body, it agitates and locally fluidizes the soil, reducing the drag and energetic cost of burrowing. RoboClam technology, which is based on the digging mechanics of razor clams, may be valuable for subsea applications that could benefit from efficient burrowing, such as anchoring, mine detonation, and cable laying. We directly visualize the movement of soil grains during the contraction of RoboClam, using a novel index-matching technique along with particle tracking. We show that the size of the failure zone around contracting RoboClam can be theoretically predicted from the substrate and pore fluid properties, provided that the timescale of contraction is sufficiently large. We also show that the nonafline motions of the grains are a small fraction of the motion within the fluidized zone, affirming the relevance of a continuum model for this system, even though the grain size is comparable to the size of RoboClam. [ABSTRACT FROM AUTHOR]

Abstract: Despite its ubiquity and its role as an ecosystem engineer on temperate intertidal mudflats, little is known of the spatial ecology of the lugworm Arenicola marina. We estimated lugworm densities and analyzed the spatial distribution of A. marina on a French Atlantic mudflat subjected to long-term clam digging activities, and compared these to a nearby pristine reference mudflat, using a combination of geostatistical techniques: point-pattern analysis, autocorrelation, and wavelet analysis. Lugworm densities were an order of magnitude greater at the reference site. Although A. marina showed an aggregative spatial distribution at both sites, the characteristics and intensity of aggregation differed markedly between sites. The reference site showed an inhibition process (regular distribution) at distances <7.5 cm, whereas the impacted site showed a random distribution at this scale. At distances from 15 cm to several tens of meters, the spatial distribution of A. marina was clearly aggregated at both sites; however, the autocorrelation strength was much weaker at the impacted site. In addition, the non-impacted site presented multi-scale spatial distribution, which was not evident at the impacted site. The differences observed between the spatial distributions of the fishing-impacted vs. the non-impacted site reflect similar findings for other components of these two mudflat ecosystems, suggesting common community-level responses to prolonged mechanical perturbation: a decrease in naturally-occurring aggregation. This change may have consequences for basic biological characteristics such as reproduction, recruitment, growth, and feeding. [Copyright &y& Elsevier]

Background. The Dniprodzerzhynsk reservoir is one of six reservoirs built on the Dnieper River, which currently supports important commercial and recreational fisheries. To date, there are no published data on the reservoir's non-commercial fish species, among which gobies are considered to be the most abundant and important species. The goal of this work was to contribute to general knowledge on local gobiid fauna, focusing on their mesohabitat preferences. Materials and methods. Sampling in the Dniprodzerzhynsk reservoir was conducted during late August of 2011 and 2012 within the framework of routine annual juvenile fish surveys in the Dnieper reservoirs. Fish were collected at sampling sites located along the reservoir shoreline using a beach seine made of mill sieving gauze (1 mm mesh size). Mesohabitat features were recorded at each beach seine haul site, and included maximum depth, substrate type, and vegetation density. These data were used to identify fish mesohabitat preferences with the aid of Ivlev's electivity index. Results. Seven gobiid species were collected: western tubenose goby, Proterorhinus semilunaris (Heckel, 1837); knout goby, Mesogobius batrachocephalus (Pallas, 1814); Pontian monkey goby, Neogobius fluviatilis (Pallas, 1814); round goby, N. melanostomus (Pallas, 1814); racer goby, Babka gymnotrachelus (Kessler, 1857); Pontian bighead goby, Ponticola kessleri (Günter, 1861); and ratan goby, Ponticola ratan (von Nordmann, 1840). Ratan goby was recorded for the first time from this reservoir. Most frequently encountered were monkey goby (76.27%), followed by western tubenose goby (32.20%), racer goby (31.36%), round goby (14.41%), bighead goby (10.17%), while knout and ratan gobies were the most rare (each accounting for 1.69%). All gobiids showed preferences for certain mesohabitat features such as bottom substrate and aquatic vegetation density. Conclusion. The gobiid fauna of the reservoir is rich and is dominated by monkey goby. The occurrence of ratan goby, an estuarine and marine species that adapted to freshwater conditions, is an evidence for ongoing Ponto- Caspian gobiid invasion to the Dnieper reservoirs. [ABSTRACT FROM AUTHOR]

Advances in fishing technologies have increased the efficiency and diversification of recreational fisheries. This poses challenges for surveying specialised or 'hard-to-reach' recreational fishers (e.g. sport fishers) that may take the majority of the recreational catch for some species, but are too rare within the general population to be sampled cost-effectively using existing methods. We trialled two new methods-time-location sampling (TLS) and online diaries-for surveying specialised recreational longtail tuna ( Thunnus tonggol) fishers. Results were compared with a concurrent traditional access point survey (APS). Online diaries were inexpensive but unsuitable for collecting representative data due to avidity, volunteerism, and differential recruitment bias. APS yielded high resolution data on catch, effort and size composition but was expensive and ineffective for sampling all components of the fishery. In contrast, TLS conducted at fishing tackle stores was cost-effective for accessing the breadth of fisher types due to the need for all fishers to purchase or to inspect fishing-related products at some point. Given the frequent absence of complete list frames for recreational fisheries, we suggest undertaking multiple TLS surveys to collect catch rate data and to simultaneously estimate population size using capture-recapture approaches in order to estimate the total recreational catch of species of interest. [ABSTRACT FROM AUTHOR]

This paper explores inherent tensions between two democratic ideals: citizen representation and accountability of the state. Specifically, I argue that the method by which state officials make themselves accountable-through their creation of the appearance of transparency-results in the exclusion of alternative, non-scientific ways of knowing, including those that are gendered, local and indigenous, because these ways of knowing often employ non-standardized methods which are not 'transparent' in the same way as science and therefore easily dismissed by state officials as indefensible to citizens' questioning. I explore this tension by drawing on examples from ethnographic work I completed with two groups of knowledge practitioners, Kwakwaka'wakw First Nations (Native American) traditional marine harvesters and government biologists, both of whom work with clams. [ABSTRACT FROM AUTHOR]

The black clam, Villorita cyprinoides, is the most important clam species landed in India. The State of Kerala has been, by far, the leading producer of the species. Nearly all the landings, about 25,000 tons (t)/year are harvested in Vembanad Lake, the largest estuary, 96 km (54 mi) long, on the west coast of India. Nearly 4,000 fishermen harvest the black clams year-round. They harvest most by hand while diving in waters from 2.1-2.7 m (7-9ft) deep. Each collects 150-200 kg (3-5 bushels)/day. Upon returning from the harvesting beds, the fishermen and their families cook the clams and separate their meats from their shells using simple sieves. Fishermen's wives sell the meats within their local villages and save some for their families to eat. The shells are sold through organized fishermen societies to various industries. A substantial quantity of sub-fossil black clam shells lies buried from 22-50 cm (9-20 in) beneath the lake sediments. They are dredged in a controlled manner and sold to the same industries. The stocks of black clams seem to be declining slowly in the southern part of the lake because the water has been getting fresher, but they are not declining in the northern half. A likely threat to the landings may he a lack offishermen in the future. [ABSTRACT FROM AUTHOR]

Thorarinsdóttir, G. G., Jacobson, L., Ragnarsson, S. Á., Garcia, E. G., and Gunnarsson, K. 2010. Capture efficiency and size selectivity of hydraulic clam dredges used in fishing for ocean quahogs (Arctica islandica): simultaneous estimation in the SELECT model. – ICES Journal of Marine Science, 67: 345–354.Estimates of capture efficiency and size selectivity for commercial dredges are important in estimating stock biomass and setting catch limits for the ocean quahog off Iceland and the United States. Ocean quahogs are long-lived, slow-growing, and sensitive to overharvest resulting from poor estimates of capture efficiency and stock biomass. Capture efficiency and size selectivity were estimated simultaneously in mixed-effect SELECT models using diver and commercial dredge experiment data from the shallow-water habitats off Iceland. Estimated capture efficiency for the commercial dredge E = 92% (CV = 8%) was high for large [107.5 mm shell length (SL)] ocean quahogs. Size selectivity followed an ascending logistic curve, with L50 = 70.5 mm SL (CV 4%), a selectivity range of 17.6 mm SL, and substantial variability among experimental dredge tows. Estimated capture efficiency was higher than that for ocean quahogs in US waters, possibly because of the deep habitats off the United States or uncertainty about dredge position during US depletion experiments. Scaling maximum selectivity from the SELECT model to one reduces correlations between size-selectivity and capture-efficiency parameters and may enhance the utility of selectivity estimates in stock assessment modelling. Our experimental and modelling approach may be useful for studies with other non-mobile benthic species. [ABSTRACT FROM PUBLISHER]

The estuarine clam Polymesoda solida is the main fishery resource in the Salamanca Island Natural Park. I sampled the clam in three interconnected lagoons (Poza Verde, El Torno and Atascosa) during the rainy period (April to November 2004). Sixty individuals were monthly collected by hand on each lagoon; 30 to analyze two condition indexes (relationship between body and shell weight and between soft dry and wet weight), yield (meat percentage) and length-weight relationships. Maturity of female gonad smears was assessed on the remaining individuals. Measures of salinity, temperature, pH, dissolved oxygen, transparency and depth, were also taken at the collection places. Increases of the condition indexes occurred when the Magdalena River showed some decreases in its level, especially at Poza Verde and El Torno. The condition indexes were higher at 27-33mm, (range where maturity size was reached). Clams from Poza Verde, the lagoon nearest to the Magdalena River, had the highest values in condition indexes, yield, fresh weight and maturity frequency. Yield was directly correlated to the condition indexes and sexual maturity. The condition index (body weight/shell weight) showed a highest multiple regression coefficient with salinity, pH and transparency (R2=74%), indicating the relevance of the hydrological regime in the regulation of the condition of the organisms. P. solida seems to be more adapted to the lowest salinities of the system (0.0-0.4), corresponding to Poza Verde, where the influence of the Magdalena river is more direct and steady. Additionally, differences found between sites in the assessed variables, emphasize the importance of considering spatial heterogeneity of this kind of lagoon estuaries, and should be taken into account for future fisheries management in the rainy period and conservation of P. solida populations. [ABSTRACT FROM AUTHOR]

The assessment of clam recruitment potential is a necessary step to improve the economic and environmental sustainability of the exploitation activities in a regulated fishery. We discuss the application of a method for estimating the clam recruitment potential in a natural nursery area (the so-called Bassona) of a northern Adriatic lagoon (Sacca di Goro, Italy). Larvae in the plankton were collected at weekly intervals, while post-larvae that settled were analysed monthly. Planktonic larval and benthic post-larval cohorts were determined, and growth and mortality rates were calculated. The theoretical formulation derived allows the estimate of the future abundance of juvenile clams during their first year of benthic life. [ABSTRACT FROM AUTHOR]

This study aimed to assess the potential effects of clam dredging and the subsequent recovery of the benthic environment. Two experimental areas located at 6 and 18m depth were established in order to analyse whether impacts and recovery of benthic environment are depth-related. Study areas were located within an area closed to dredging and two different plots were established at both depths. One of the plots was subjected to intense clam dredge-fishing, while the other was undisturbed and therefore used as control. Sampling followed a BACI design, with samples for macrobenthic, meiobenthic and sediment particle size analysis being taken by SCUBA divers from both areas before and after fishing stress. For both depths, impacts on the benthic environment were very low resulting in high recovery rates. Nevertheless, at shallower depths communities demonstrated a faster recovery. It was shown that depending on the faunal component used as a bioindicator, different results can be observed. Generally deposit-feeding organisms with scales or chitinous plates and vermiform shape (mainly crustaceans, polychaetes and ophiuroids), without external protection, were the most affected by dredging, while some polychaetes without external protection and with a carnivorous feeding mode seemed to be enhanced by fishing. The low level of perturbations induced by the dredging activities was comparable to the impact of surface waves on the bottom, as experiments were undertaken in wave-dominated environments. The coexistence of storm events during the study period proved to have similar or even more deleterious effects on the benthic environment. It appears that communities from hydrodynamic fishing grounds that are well adapted to natural physical stress are not highly affected by dredging. [Copyright &y& Elsevier]

Abstract: Suppression–Subtractive Hybridization (SSH) was used to identify differentially expressed Ruditapes decussatus genes against the protozoan Perkinsus olseni infection. A forward and a reverse subtraction were carried out to identify up- and down-regulated genes in both haemocytes and gills of clams naturally infected with P. olseni. New genes, candidates for further investigation into the functional basis of resistance to pathogens, have been detected for the first time in the clam (R. decussatus). A total of 305 differentially expressed sequences were obtained, 221 of them in haemocytes and 84 in gills of infected clams. The number of ESTs with potential similarity with known genes was 97, 42 among them were related with immunity and stress related functions. The pattern of expression of the immune selected genes was studied by quantitative PCR with samples of naturally Perkinsus infected clams and compared with samples from an in vitro infection of clam haemocytes with Perkinsus zoospores. The maximum expression was found 1h post infection. The complete open reading frames of selected sequences (Rd adiponectin-C1q and Rd DAD-1) were determined. Our results provide new insights into the molecular basis of host–pathogen interactions in R. decussatus. [Copyright &y& Elsevier]

Abstract: The pathological condition of the short-neck clam Ruditapes philippinarum was surveyed along the coast of Kumamoto, Japan, in June 2004. DNA sequences of the non-transcribed spacer region and internal transcribed spacer region flanking 5.8S rRNA identified Perkinsus olseni among the clams. Ray’s fluid thioglycollate medium assay indicated that 96.7% of the clams surveyed from the Kiguchi River tidal flat (native clams, Stn KR-N) and 96.7% of the clams surveyed from the Midori River tidal flat (Stn MR) were infected with P. olseni with an infection intensity of 464,278 and 199,937 Perkinsus cells/gram tissue wet weight (gWW), respectively. In contrast, 66.7% of the clams imported from China and stored along the Kiguchi River tidal flat (Stn KR-I) and 20.2% of clams from the Arao tidal flat (Stn AT) were infected with P. olseni with an infection intensity of 37,547 and 3382 Perkinsus cells/gWW, respectively. Brown ring disease was detected in the clam population from Stn KR-I at a prevalence of 90.0%. Polymerase chain reaction and the 16S rRNA sequence suggested that the agents of brown ring disease observed at Stn KR-I were Vibrio tapetis-like bacteria. Sporocysts and metacercariae of unidentified trematodes were also observed in the gonads and mantle of the clams from Stn KR-I, Stn MR, and Stn AT, at prevalences of 7.1–42.9%. Metacestodes (larval tapeworms) were found in the foot and digestive gland at a prevalence of 52.5%, 30.0%, and 14.3% in clams from Stns MR, AT, and KR-N, respectively. Histology also showed massive hemocyte infiltration and inflammation among clams heavily infected with P. olseni. Castration of the follicle was typical among clams infected with the trematode. The data indicate that most of the clams along the coast of Kumamoto are infected with various pathogens at various rates of infection, and these pathogens could have negative effects on the clam population in the long term. [Copyright &y& Elsevier]

Abstract: Estrogenic potency of 17-β estradiol (E2) was evaluated for the first time in both sexually undifferentiated (during resting phase, at the very early stage of gametogenesis) and differentiated (in pre-spawning phase) clams (Tapes philippinarum), following waterborne exposure for 7 and 14 days to various E2 concentrations (0, 0+acetone, 5, 25, 50, 100 and 1000ng/L). Vitellogenin (Vg)-like protein levels were evaluated in both haemolymph and digestive glands by the alkali-labile phosphate (ALP) assay. In the resting phase of clams, exposure for 7 days to all E2 concentrations tested resulted in significant increases in ALP in haemolymph with respect to controls. Conversely, no statistically significant differences were observed in digestive gland from E2-exposed bivalves, compared with controls. After 14-days exposure, ALP significantly increased in haemolymph from 1000ng E2/L-exposed clams and in digestive gland from 5ng E2/L-exposed animals. Interestingly, in the pre-spawning phase of clams, significant decreases in ALP levels were recorded in haemolymph from females exposed for 7 days, whereas no differences were observed in males. No significant variations were observed in ALP content in digestive gland from both females and males. ALP levels in haemolymph were shown to increase significantly in females exposed for 14 days to 50ng E2/L, and in males exposed to 100ng E2/L. Exposure for 14 days to all the E2 concentrations tested resulted in significant increases of ALP levels in the digestive gland of females. Conversely, variations in ALP content of male digestive glands were not significant. Results obtained appeared controversial and somewhat difficult to explain. Indeed, no univocal response by clams was observed after 7 and 14 days exposure to E2. Further studies need to elucidate the role of E2 in promoting Vg induction in clams. [Copyright &y& Elsevier]

A series of experiments were conducted to evaluate the effects of diet, stocking density and environmental factors on the growth, survival and metamorphosis of short neck clam Paphia malabarica larvae. These experiments examined the following factors: diet [ Isochrysis galbana, Nannochloropsis salina and a mixture of I. galbana and N. salina (1:1 w/w)], stocking density (1, 3, 5 and 7 larvae mL−1), light intensity (unshaded, partially shaded and fully shaded) and water filtration (unfiltered and sand filtered). Results indicated that N. salina could replace 50% of I. galbana as a food source for the clam larvae with an increase in growth, survival (47.2%), metamorphosis (33.5%) and early settlement. Larval growth decreased significantly with increasing stocking density. A density of 1–3 larvae mL−1 appeared to be optimal for normal growth of clam larvae. Neither diet nor stocking density used in the study had a significant effect on larval survival. Under partially shaded (light intensity=1000–5000 lx) and fully shaded (light intensity <1000 lx) conditions, larval growth was significantly faster than under direct sunlight (unshaded). Larvae grew significantly faster in the unfiltered water than in the filtered water. [ABSTRACT FROM AUTHOR]

Abstract: Brown ring disease (BRD) in the Manila clam is induced by the bacterium Vibrio tapetis. During the infection process, the pathogen enters the extrapallial compartment of the Manila clam and induces the formation of a characteristic brown deposit that gives the disease its name. Although post-infection processes have been widely described for this disease, the mechanisms of entry of the bacteria into the extrapallial compartment remains unclear. From relationships between clam size and BRD prevalence, and between grain-size distribution in natural habitats and prevalence, we propose a simple explanation for this step: V. tapetis benefits from mechanical disruptions of the periostracal lamina or valve margins to colonize the extrapallial compartment. Such disruptions may be induced by the presence of large sediment grains in natural habitats, which become lodged in the shell opening. This hypothesis suggests that limiting handling of clams may help to limit development of BRD in cultured clam beds. [Copyright &y& Elsevier]

Abstract: The effects of β-glucans on several immune functions of carpet shell clam (Ruditapes decussatus) and Mediterranean mussel (Mytilus galloprovincialis) hemocytes were determined. Nitric oxide (NO) production increased significantly in β-glucan treated mussels and clams. In mussels, β-glucans increased by themselves the release of free oxygen radicals and also were able to enhance the phorbol 12-myristate 13-acetate (PMA) mediated effect on this hemocyte activity. However, high doses of β-glucans when combined with zymosan decreased this respiratory burst. In clams, hemolymph treated with several doses of β-glucans limited the growth of the three bacteria, Vibrio algynolyticus (strain TA15), Vibrio splendidus (strain TA2) and Escherichia coli (strain ATCC 13706). This modulation on the antibacterial activity, however, was not observed when mussel hemolymph was incubated with β-glucans. These results suggest that the immune responses of these animals can be up and down modulated by external stimuli and, although clams and mussels are both relatively closely related species, their behaviour concerning immune responses can be different. [Copyright &y& Elsevier]

Abstract  In this study, the energy budget of the Manila clam, Ruditapes philippinarum, was evaluated after one-week acclimation periods at 5, 10, 15, 20, and 25°C. Small clams (151 ± 12 mg DW) and large clams (353 ± 16 mg DW) were fed with the microalgae, Isochrysis galbana. Filtration rate, ingestion rate, assimilation efficiency, oxygen-consumption rate, and ammonia excretion rate were measured. Both filtration rate and ingestion rate of small and large clams were found to be related to temperature. The highest Q 10 values were measured in the range 15–20°C for both small and large clams. Assimilation efficiency of both small and large clams was not significantly influenced by temperature, although the maximum mean values were detected at 20°C. Oxygen consumption rate and ammonia excretion rate of small and large clams were found to be related directly to temperature over the entire range, with a maximum being detected at 25°C. The highest Q 10 value was estimated in the range 10–15°C with regard to oxygen consumption rate, and in the range of 15–20°C with regard to ammonia excretion rate. Scope for growth (SFG) was positive at all temperatures, achieving a maximum value at 20°C in both small and large clams, primarily as a consequence of the enhanced ingestion rate which offset the concomitant elevation in the metabolic rate. In this study we have estimated the thermal optimum for this species at 20°C. [ABSTRACT FROM AUTHOR]

Baker, P., Austin, J. D., Bowen, B. W., and Baker, S. M. 2008. Range-wide population structure and history of the northern quahog (Merceneria merceneria) inferred from mitochondrial DNA sequence data. – ICES Journal of Marine Science, 65: 155–163.The northern quahog (Mercenaria mercenaria) is a commercially important bivalve distributed in the NW Atlantic from Florida to Nova Scotia. We report on population genetic analyses, based on 528 bp of mitochondrial COI gene, for 10 locations across the range of M. mercenaria (n = 297). Our analyses revealed no evidence of cryptic evolutionary lineages, but modest population structure (ϕST = 0.0213; p = 0.0019) with a significant partition at Cape Hatteras and a weakly supported partition at Cape Cod. Samples from the west coast of Florida (Gulf of Mexico) were not significantly different from most Atlantic populations, despite a 600 km gap in distribution along South Florida, and a well-documented biogeographic break at Cape Canaveral. These findings support the thesis that the Gulf of Mexico population is the product of a recent introduction. Samples north of Hatteras decrease in diversity with increasing latitude, probably indicating post-glacial range extension, a conclusion supported by a highly significant Fu's F-statistic (−99.14; p < 0.001) indicating population expansion. Mercenaria mercenaria stocks in the Atlantic include a single evolutionary unit divided into at least three closely related populations, though this does not preclude regional adaptive differences between northern, central, and southern populations. [ABSTRACT FROM PUBLISHER]

Abstract: Brown Ring Disease (BRD) is a bacterial disease caused by the pathogen, Vibrio tapetis. The disease induces formation of a brown deposit on inner shell of the Manila clam, Ruditapes philippinarum. Development of this disease is correlated with a decrease in the condition index of infected clams. Experiments were conduced in order to assess the effect of the development of BRD on two parameters affecting the energy balance of the clams: the clearance and the respiration rates. Experiments were performed in a physiological measurement system that allowed simultaneous measures of clearance and respiration rates. During both acclimation and measurements clams were fed with cultured T-iso and temperature was close to seasonal field temperature (10°C). Our results showed that severely diseased clams (conchiolin deposit stage, CDS≥4) are subject to weight loss in comparison to uninfected ones, indicating that BRD induces a disequilibrium in the energy balance. We demonstrated a reduction of the clearance rate of severely diseased clams which led to a decrease in energy acquisition. Respiration rate showed a significant decrease with BRD symptoms, but evidence in the literature allowed us to hypothesize that energy mobilised for an immune response and lesion repair increases overall organism maintenance costs. Both factors should thus contribute to the degradation of the energy balance of diseased clams. Because effects of BRD on naturally infected clams only appears significant for CDS≥4, when brown ring assumes a significant place on the inner shell, we consider that the Manila clam is tolerant of low disease levels. [Copyright &y& Elsevier]

Abstract: The effects of yttrium on properties and microstructure for China Low Activation Martensitic (CLAM) steel have been investigated. The tensile test shows that the addition of 0.2% yttrium decreases the strength of CLAM steel before irradiation. The results obtained by positron annihilation lifetime measurements of the CLAM, F82H and T91 steels irradiated by 80MeV 19F ions to 10dpa demonstrate that the irradiation resistant property of CLAM steel with yttrium is much better than that of other two steels. The SEM and TEM observations suggest the addition of yttrium both refines the martensitic lath structure and leads to the precipitation of big Y2Fe17C0.75 compound. [Copyright &y& Elsevier]

Abstract: The liquid metal LiPb blanket design is one of the most promising designs for future fusion power reactors and under wide research in the world. The first liquid metal LiPb loop in China named DRAGON-I was built in 2005 in order to do research on characteristics of liquid metal LiPb such as its corrosion to structural materials of the blankets and so on. The first corrosion experiment in flowing LiPb with a speed of 0.08m/s at 480°C for 500h was done in October 2005 on CLAM (China low activation martensitic) steel and 316L stainless steel for comparison. The weights and compositions, etc. of the specimens before and after corrosion experiment were tested and analyzed, the microstructures of the specimens were also inspected by SEM. The results show that the corrosion of CLAM steel is relatively slight, while that for 316L is obvious and very serious. Further study on corrosion behavior of CLAM for longer time experiment in liquid LiPb at different temperatures and flow speeds will be carried out in the near future. [Copyright &y& Elsevier]

A quantitative assay for Plesiomonas shigelloides in pure culture and clams based on the competitive polymerase chain reaction was developed. This is the first report for quantitative detection of P. shigelloides by competitive PCR. Forward (PS-F), reverse (PS23RV3), and hybrid primers were designed, and the specificity of the forward and reverse primer for P. shigelloides was proven. An internal standard DNA sequence was synthesized by PCR, with the hybrid primer as the forward primers and PS23RV3 as the reverse primer. A single concentration (0.588 pg/PCR) of internal standard (IS) was used for competitive PCR. The lowest level of detection of P. shigelloides was 80 CFU per PCR in pure culture, 240 CFU/g of clam tissue without enrichment, and 40 CFU/g of clam tissue after 7 hrs. nonselective enrichment at 37°C. There was a linear relationship between the log of the ratio of the relative fluorescent intensities of amplified target DNA bands to the internal standard DNA bands (IS) and the log of the CFU within a certain range in pure cultures and in clam tissue either with or without enrichment. The linear range with cells from a pure culture was the DNA derived from 8.0 × 101 to 8.0 × 104 CFU per PCR while with clam tissue, the linear range was the DNA derived from 2.4 × 102 to 2.4 × 105 CFU/g of tissue (1.2 × 101 to 1.2 × 104 CFU per PCR) without enrichment, and 4.0 × 101 to 1.2 × 104 CFU/g of clam tissue with enrichment, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The genetic structure of seven different populations of the surf clam Mactra veneriformes along the coast of China was investigated by Inter-Simple Sequence Repeats (ISSR) fingerprinting of 210 individual clams. Of the 240 ISSR loci tested, 235 (97.9%) were polymorphic. We found a clear tendency for higher F ST values and lower gene flow levels between the populations with increasing geographical separation. The seven different geographic populations can be divided into three subgroups: Liaoning, Qingdao/Lianyungang, and Ningbo based on the UPGMA dendrogram of Nei''s genetic distance. These results indicated that isolation of geographic distance played an important role in population differentiation. [Copyright &y& Elsevier]