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Shell Length (shell + length)
Selected AbstractsLinking environmental warming to the fitness of the invasive clam Corbicula flumineaGLOBAL CHANGE BIOLOGY, Issue 12 2009MARKUS WEITERE Abstract Climate warming is discussed as a factor that can favour the success of invasive species. In the present study, we analysed potential fitness gains of moderate warming (3 °C above field temperature) on the invasive clam Corbicula fluminea during summer and winter. The experiments were conducted under seminatural conditions in a bypass-system of a large river (Rhine, Germany). We showed that warming in late summer results in a significant decrease in the clams' growth rates (body mass and shell length increase) and an increase in mortality rate. The addition of planktonic food dampens the negative effect of warming on the growth rates. This suggests that the reason for the negative growth effect of temperature increase in late summer is a negative energetic balance caused by an enhanced metabolic rate at limited food levels. Warming during early summer revealed contrasting effects with respect of body mass (no warming effect) and shell length (increased shell growth with warming). This differential control of both parameters further enhances the loss of the relative (size-specific) body mass with warming. In contrast, warming in winter had a consistently positive effect on the clams' growth rate as demonstrated in two independent experiments. Furthermore, the reproduction success (as measured by the average number of larvae per clam) during the main breeding period (April) was strongly enhanced by experimental warming during winter, i.e. by eight times during the relatively cold winter 2005/2006 and by 2.6 times during the relatively warm winter 2007/2008. This strong, positive effect of moderate winter warming on the clams' fitness is probably one reason for the recent invasion success of C. fluminea in the northern hemisphere. However, warm summer events might counteract the positive winter warming effect, which could balance out the fitness gains. [source] A test of methods for estimating population size of the invasive land snail Achatina fulica in dense vegetationJOURNAL OF APPLIED ECOLOGY, Issue 4 2002Paul G. Craze Summary 1Physical inaccessibility often complicates censuses of poorly mobile organisms. We therefore assessed the effectiveness of using a sample of quadrat counts to generate a population estimate corrected for inaccessible areas. The result is directly applicable to management of the introduced snail Achatina fulica on Ile aux Aigrettes, a small island off Mauritius, but also has implications for counting this and similar species elsewhere. Accurate counting of A. fulica is important given that this species is such a widespread and serious pest. 2Counts were made in 17 quadrats taken from a grid covering the island. These were used to produce one population estimate by interpolating for the rest of the grid using GIS software (method 1). A second estimate assumed equal density of snails in accessible and inaccessible parts of the 17 quadrats, again with the population estimate interpolated (method 2). 3Four further quadrats were cleared of vegetation and, by comparison of counts before and after clearance, the relationship between initial count and true snail number was estimated. This resulted in two further population estimates, with the relationship used to adjust counts in the 17 experimental quadrats before interpolation (methods 3 and 4). 4All four estimates were tested using 35 additional quadrats of two types. Type 1 quadrats were physically cleared of vegetation; type 2 quadrats were fully accessible without clearance. Predicted counts in these quadrats were assessed for accuracy by comparison with actual counts. 5The method 1 estimate was clearly inadequate; method 4 gave a consistent overestimate; method 2 gave the smallest error in both quadrat types. In type 1 quadrats, method 2 and 3 estimates were not significantly different and method 2 had a slight tendency to underestimate. Overall, for studies of A. fulica, method 2 is recommended. However, it should be noted that the study took place towards the end of the wet season. In the dry season, damp refuges under inaccessible vegetation may be more important and methods 3 and 4 may then give a better estimate. 6The population of A. fulica with shell length > 10 mm on Ile aux Aigrettes near the end of the wet season in 2000 was between 37 300 and 45 100, with 39 700 being the best estimate. 7The results underline the importance of considering inaccessible areas when accurate counts of species are needed, and a method is suggested by which a simple census technique can be adjusted. In the case of A. fulica, more accurate estimates of population size and distribution are invaluable in the management, monitoring and eradication of this invasive species. [source] Mechanism of a plastic phenotypic response: predator-induced shell thickening in the intertidal gastropod Littorina obtusataJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2007J. I. BROOKES Abstract Phenotypic plasticity has been the object of considerable interest over the past several decades, but in few cases are mechanisms underlying plastic responses well understood. For example, it is unclear whether predator-induced changes in gastropod shell morphology represent an active physiological response or a by-product of reduced feeding. We address this question by manipulating feeding and growth of intertidal snails, Littorina obtusata, using two approaches: (i) exposure to predation cues from green crabs Carcinus maenas and (ii) reduced food availability, and quantifying growth in shell length, shell mass, and body mass, as well as production of faecal material and shell micro-structural characteristics (mineralogy and organic fraction) after 96 days. We demonstrate that L. obtusata actively increases calcification rate in response to predation threat, and that this response entails energetic and developmental costs. That this induced response is not strictly tied to the animal's behaviour should enhance its evolutionary potential. [source] GROWTH OF CULTURED ABALONE, HALIOTIS FULGENS, USING NATURAL ALGAL DIETSJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Pérez-Estrada, C. J.1,2, Serviere-Zaragoza, E.1, Mazariegos-Villareal, A.1, Reynoso-Granados, T.1 & Monsalvo-Spencer, P.1 1Centro de Investigaciones Biológicas del Noroeste (CIBNOR). P.O. Box 128, La Paz, Baja California Sur. 23000. México; 2Universidad Autónoma de Baja California Sur. Carretera al Sur km. 5.5 o 23080 o La Paz, B. C. S. Algal diets have been evaluated and used extensively for the aquaculture of abalone, especially in Japan. In other areas little is known about the nutritional value of the algae that the local abalone consume. In Mexico, regional hatcheries use Macrocystis pyrifera as a main source of natural food. Kelp availability, year round, has not generally been a problem for abalone aquaculturists. Most difficulties occur during severe storms, which may prevent access to kelp beds. El Niño also caused widespread destruction of M. pyrifera. In this study, growth rates of juvenile green abalone Haliotis fulgens, 31.7 " 1.5 mm shell length and 2.5 " 0.2 g body weight were evaluated during 136 days. Juveniles were fed with some of the algae used in regional hatcheries, Macrocystis pyrifera, Egregia menziesii, Eisenia arborea, Porphyra sp. and Ulva sp. Shell length growth rates varied between 2 mm day-1 for Ulva sp. and 18 mm day-1 for M. pyrifera. Body weight rates ranged from no growth for Ulva sp. to 14 mg day-1for E. menziesii. The percent of survival was between 46 and 75 %. Ulva sp. showed the lowest protein content followed by E. menziesii, E. arborea, M. pyrifera and Porphyra sp. [source] Laboratory Study of the Intracapsular Development and Juvenile Growth of the Banded Murex, Hexaplex trunculusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2010Youssef Lahbib Spawning, intracapsular development, and juvenile growth of Hexaplex trunculus were investigated in the laboratory. Each female deposited nightly an average of 138.83 ± 58.70 yellowish egg capsules per spawn. Each capsule contained 358.57 ± 102.45 eggs with an average diameter of 207.23 ± 18.18 µm. Observations on the intracapsular development showed that H. trunculus is a spiralian unequal-cleaving gastropod, with polar lobes being extruded at early segmentation. Embryos develop within the egg capsule through the provision of nurse eggs as an extraembryonic source of nutrition. Hatching occurred after 52 d of incubation. However, the hatchlings were not completely metamorphosed because velum was still present. At this moment, the average of shell length was 1.04 ± 0.13 mm (n = 107). The average number of hatchlings per capsule was 14.73 ± 4.40 including 3.4% malformed individuals. During the first 5 mo of life, juveniles rapidly grew in shell length (growth rate = 3.56 mm/mo). However, in the remaining period (26 mo), growth rhythm decreased considerably (growth rate = 0.64 mm/mo). The weight growth rhythm was irregular with alternation between fast and slow increases observed over the rearing experiment. This kind of data could be useful for assessing the potential of this species for future molluscan aquaculture programs. [source] Comparison of Development and Larval Growth of Four Venerid ClamsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2005Young-Baek Hur The development and larval morphology of four venerid calms, Ruditapes philippinarum, Mactra veneriformis, Cyclina sinensis, and Meretrix lusoria, which cohabit the intertidal zone in western coastal Korea, were compared using laboratory culture techniques. At 87 ,m, the fertilized eggs of C. sinensis and M. lusoria were the largest and at 53 ,m, those of M. veneriformis were the smallest. D-shaped larvae of M. lusoriu were the largest and those of M. veneriformis were the smallest measuring at 135 ,m and 89 ,m, respectively. D-shaped larvae of R. philippinarum and M. lusoria had symmetrical shoulder angles and an elliptical ventral form, in contrast to the asymmetrical shoulder angles and round ventral forms of M. veneriformis and C. sinensis. In general, pediveliger larvae of all species in the study were yellow, but those of M. veneriforks and C sinenis were a more pronounced yellow. In between the early D-shaped and pediveliger stage, 7 and 17 d elapsed for M. lusonia and C. sinensis larvae, respectively. In the early larval stages for all species, the sheU length was longer than the height. However, shell length and height later became approximately the same size in all species except R. philippinarum, which exhibited a flat shape. These results indicate that for these four venerid clams, the different characteristics in larval growth and external morphology provide the evidence necessary for larval identification of natural seed production despite the fact that they spawn concurrently in the intertidal zone. [source] Growth and Survival of the Blood Ark Anadara ovalis (Bruguière, 1789) Cultured in Mesh Bags on Soft-Bottom Sediments in the Coastal Waters of GeorgiaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2001Alan J. Power Annual growth and survival rates were measured for blood arks Anadara ovalis (Bruguière 1789) cultured in mesh bags that were placed at the spring-low-water mark in soft-bottom sediments of the Skidaway River, Georgia. The feasibility of growing the arks to a marketable size using this technique was assessed by determining the effects of stocking density and biofouling on growth and survival. Two replicate densities of 190 (low) and 400 (high) arks per mesh bag (mean shell length 31.97 mm) were planted in early September 1999. In April 2000, the arks cultured at the lower density had a significantly larger size (44.99 mm) than at the higher density (43.83 mm), with growth rates of 1.85 mdmo, and 1.69 mm/mo, respectively. Growth decreased considerably in the subsequent months (low: 0.17 mm/mo; high: 0.30 mm/mo). There was no significant difference in ark size between treatments after a year's growth in late August 2000 (low: 45.76 mm, 1.15 mm/mo; high: 45.31 mm, 1.11 mm/mo). Similarly, no significant difference in annual survival rates between stocking densities occurred (low: 42.89%; high: 40.25%). The present findings indicate that this method of growing arks to market size has potential to contribute to future endeavors to develop an aquaculture fishery for the blood ark in the coastal waters of Georgia. [source] Comparison of Three Culture Methods for the Intensive Culture of Northern Quahog Seed, Mercenaria mercenariaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2001Timothy J. Pfeiffer A number of approaches have been utilized for growing bivalve hatchery seed (1 mm) to a size suitable for field planting (< 8 mm) but few have been directly compared. This study evaluated the growth and survival of northern quahog seed in three different culture systems and two different stocking densities. The three systems were: 1) a stacked-tray unit with downward water flow; 2) traditional upweller culture units with water flowing upward without seed bed expansion; and 3) upweller culture units with water flowing upward at fluidization velocities to provide seed bed expansion. The two stocking densities were 1.0 and 3.0 g whole wet weight clam/cm2 respectively. During each trial period the seed clams were fed a 1% daily ration (% dry weight algae per wet weight clam per day) of the cultured diatom Chaetoceros muelleri. After 14 d of culture at the 1.0 g whole wet weight/cm2 stocking density, seed clams (4.4 ± 0.6 mm initial shell length) under fluidized-flow condition exhibited better growth (0.54/d), and a greater final shell length (5.9 ± 1.0 mm). At the high density stocking conditions, after 28 d of culture, seed clams (4.2 ± 0.6 mm initial shell length) in the fluidized-flow culture conditions again exhibited better growth rate (0.031/d) and a greater final shell length (6.0 ± 1.0 mm). The preliminary evaluation of fluidized-flow for seed clam culture in land-based nurseries indicates its potential as a suitable alternative to raceway, downwelling, or traditional forced-flow culture methods. [source] Construction of microsatellite-based linkage maps and identification of size-related quantitative trait loci for Zhikong scallop (Chlamys farreri)ANIMAL GENETICS, Issue 6 2009A. Zhan Summary We constructed the microsatellite-based linkage maps using 318 markers typed in two F1 outbred families of Zhikong scallop (Chlamys farreri). The results showed an extremely high proportion (56.2%) of non-amplifying null alleles and a high ratio (30%) of segregation distortion. By aligning different individual-based linkage maps, 19 linkage groups were identified, which are consistent with the haploid chromosome number of Zhikong scallop. The integrated linkage map contains 154 markers covering 1561.8 cM with an average intermarker spacing of 12.3 cM and 77.0% of genome coverage. We found that the heterogeneity in recombination rate was not determined by sexes but by different individuals on 18 linkage regions. The phenotypic marker of general shell colour was placed on LG4, which was flanked by microsatellite markers CFLD064 and CFBD055. Four size-related traits including shell length (SL), shell width (SW), shell height (SH) and gross weight (GW) were analysed to identify the putative quantitative trait loci (QTL). Under the half-sib model, using dam as common parent, three, two, two and one QTL affecting SL, SW, SH and GW exceeded the genome-wide thresholds respectively. While using sir as common parent, a larger number of QTL were detected for these four traits: four, five, three and two for SL, SW, SH and GW respectively. The single QTL explained 3.7,19.2% of the phenotypic variation. The linkage map and the QTL associated with economic traits will provide useful information for marker-assisted selection of Zhikong scallop. [source] Growth and feeding in juvenile triploid and diploid blacklip abalone, Haliotis rubra (Leach, 1814), at two temperaturesAQUACULTURE NUTRITION, Issue 6 2006W. LIU Abstract Growth and feeding of juvenile triploid and diploid blacklip abalone Haliotis rubra (Leach, 1814) were investigated at two temperatures of 17 and 21 °C over a 50-day period. There were no differences in growth between triploid and diploid abalone as measured by shell length and body weight. Both triploid and diploid abalone increased in length but not in weight at 21 °C. Condition indices were similar for triploid abalone maintained at both temperatures; however, those for diploid abalone were significantly higher at 17 °C than at 21 °C. Food intake was significantly greater yet feed conversion efficiency was significantly lower in triploid than in diploid abalone. Both the feeding variables were independent of temperature. On average, diploid abalone were able to convert 1 g of dry food ingested to 0.58 g of body weight, but triploid abalone only 0.44 g. [source] Variation in clearance and ingestion rates by larvae of the black-lip pearl oyster (Pinctada margaritifera, L.) feeding on various microalgaeAQUACULTURE NUTRITION, Issue 1 2003M.S. Doroudi Abstract Clearance rate (CR) and ingestion rate (IR) of different sizes (89, 125 and 188 ,m shell length) of Pinctada margaritifera larvae were determined when feeding on various microalgae. The microalgae tested were the diatoms, Chaetoceros muelleri and C. simplex, and flagellates, Tahitian Isochrysis aff. galbana, Pavlova lutheri and P. salina at 5 or 10 cells ,L,1. Both CR and IR of microalgae tested in this study increased with increasing larval size; but at all larval sizes, diatoms resulted in lower CR and IR. Of the microalgae tested, P. margaritifera larvae showed greatest CR and IR with the two Pavlova spp. Maximum CR for P. salina was 10.5, 21.2 and 29.7 ,L h,1 for larvae with shell lengths of 89, 125 and 188 ,m, respectively. The highest IR values for P. margaritifera larvae with shell lengths of 89, 125 and 188 ,m were 8.7, 81.0 and 165.7 cells·larva,1 h,1, respectively. CR and IR of P. salina were approximately five times higher than those recorded for C. muelleri and C. simplex. [source] Optimal protein level in a semipurified diet for juvenile greenlip abalone Haliotis laevigataAQUACULTURE NUTRITION, Issue 4 2000T.A. Coote To optimize dietary protein level in relation to growth, semipurified diets with an essential amino acid profile similar to that of the soft body profile were fed for 59 days to young greenlip abalone, Haliotis laevigata (initial shell length, 15,25 mm). Animals were housed in 10-L acrylic tanks, with flow-through seawater supplied at 1 L min,1 (20 °C, salinity= 36 g L,1). Protein level of feeds ranged from 122 g kg,1 to 461 g kg,1 crude protein (CP) on an ,as is' basis. Second-order polynomial regression analysis of specific growth rate indicated that maximal growth occurs at 270 g kg,1 CP. The protein and energy components of the feed were estimated to have a digestibility of 71.7% and 55.6%, respectively. [source] Effect of sandy and muddy substrates on the growth and survival of the freshwater clam Galatea paradoxa (Born 1778)AQUACULTURE RESEARCH, Issue 9 2010Daniel Adjei-Boateng This study was conducted to determine the effect of a sandy and muddy substrate on the growth and survival of three size-classes of Galatea paradoxa (Born 1778). The experiment was conducted over a 6-month period in a 1000 m2 pond at the research farm of the Faculty of Renewable Natural Resources. Three size classes (shell length) of G. paradoxa categorized as small (20,30 mm), medium (31,40 mm) and large (>40 mm) were used to ascertain the effect of a sandy and muddy substrate on growth performance. Growth in general was very slow, between 1.4 and 2.4 mm over the 6-month experimental period. The lengths measured at the end of the experiment were also significantly different. However, the mean length gained and the specific growth rate for the three size classes in the two substrates (sandy and muddy) were not significantly different (P>0.05). The results of this study indicate that the pond environment is not suitable for the culture G. paradoxa as the species is adapted to life in a river with its filter-feeding activity dependent on the water current. The effect of the substrate type on growth was not significant. However, the substrate type did affect survival, with sandy substrates yielding in better survival than muddy ones. [source] Divergent selection for shell length in two stocks of small abalone Haliotis diversicolorAQUACULTURE RESEARCH, Issue 6 2010Wei-Wei You Abstract To determine whether genetic improvement can be attained through a selective breeding programme, divergent selection for shell length was applied to two stocks of Haliotis diversicolor. Stock A was descended from the cross between males from a Japanese wild population and females from a Taiwan aquacultured population and Stock B was from the Taiwan cultured population, which had been successively cultured in mainland China for about 10 generations. The 10% largest and 10% smallest abalones for each of these two stocks were selected as parents for the large-selected and small-selected lines respectively. Equal numbers of abalone were randomly chosen from the two stocks to serve as parents for the control lines before the selection. The selected and control lines were reared under the same conditions at early juvenile, later juvenile and grow-out stages. Stock A showed a significantly higher response to selection and realized heritability than Stock B (P<0.01). The large-selected line of Stock A and Stock B grew 12.79% and 4.58% faster than their control lines on shell length respectively. The average realized heritability for shell length was 0.441±0.064 for Stock A and 0.113±0.013 for Stock B. Responses to selection were different at different ages in each stock and the body weights of the selected lines were significantly different from the control lines in both stocks at the grow-out stage. Asymmetric responses to selection in the two directions were also observed in both stocks. Differences in response to selection and realized heritability between the two stocks are presumably due to genetic variability. [source] Growth and survival of three small abalone Haliotis diversicolor populations and their reciprocal crossesAQUACULTURE RESEARCH, Issue 13 2009Wei-Wei You Abstract The aquaculture industry of small abalone Haliotis diversicolor in southern China is now close to collapse because of high mortality at the grow-out stage. To examine if survival and growth (shell length increase) could be improved by cross breeding among populations, a 3 × 3 complete diallel cross was conducted among three populations from Japan (A), Taiwan (B) and Vietnam (C). Performances in growth rate and survival at early juvenile, later juvenile and grow-out stages were compared among the six reciprocal cross lines and three parental lines. Magnitude of heterosis for survival and growth varied among cross lines in the three growing stages. As to mid-parent heterosis, HAB was significantly (P<0.01) higher than HAC and HBC at all three growing stages for both growth and survival, and all mid-parent heterosis fell between the two corresponding single-parent heterosis. HAB was 6.84% for shell length and 69.09% for survival at Day 420. Our results of high survival heterosis in line AB and line BA show that crossbreeding between different populations can benefit the small abalone breeding programs and the industry. [source] Effects of the initial size, stocking density and sorting on the growth of juvenile Pacific abalone, Haliotis discus hannai InoAQUACULTURE RESEARCH, Issue 10 2009Fucun Wu Abstract During winter months, a novel overwintering mode of transferring juvenile abalones to open seawaters in southern China rather than keeping them in closed land-based nursery systems in northern China is a popular practice. The initial size, stocking density and sorting are among the first considerations when establishing an abalone culture system. This study aimed to investigate the effects of these factors on the growth of juvenile Pacific abalone, Haliotis discus hannai Ino, during overwintering. Juvenile abalones were reared in multi-tier basket form for overwintering in open seawaters in southern China for 106 days. The daily growth rates (DGRs) in the shell length of all experimental groups ranged from 67.08 to 135.75 ,m day,1, while the specific growth rates (SGRs) were 0.2447,0.3259% day,1. Variance analysis indicated that both DGRs and SGRs in shell length were significantly affected by the initial body size and stocking density. Furthermore, the effects of stocking density on DGRs and SGRs varied with the initial size. However, sorting abalones according to their initial sizes may not be necessary in practice as sorting did not alter growth significantly at all densities in this study. Factors potentially affecting abalone growth such as genetic control and intraspecific competition were discussed. [source] Effect of water temperature and diet on growth and mortality of Neptunea arthritica juvenilesAQUACULTURE RESEARCH, Issue 4 2009Richard M Miranda Abstract The growth and mortality of Neptunea arthritica juveniles hatched from different egg masses (controlled conditions and field) reared at 10 and 15 °C, and provided with sardine (D1) and polychaete (D2) as foods were evaluated. Results showed that diet type and water temperature significantly affect the growth and mortality. Interaction between these factors reflected robust relationship among them, but restricted exclusively to growth. Through the study period, juveniles treated at 10 °C showed maximum increments of 2.5 mm (shell length), 2.3 mm (shell width) and 0.25 g (body weight) from their initial size. While maximum values of those treated at 15 °C for the above-mentioned parameters were 7.6 mm, 5.5 mm and 1 g respectively. In both cases, these increments were recorded for individuals fed with sardine. Mortality was significantly affected by diets and water temperature, which significantly increased under D2 [10 °C (20,67%), 15 °C (70,87%)] or 15 °C [D1 (30,83%), D2 (70,87%)]. According to the results, juveniles of N. arthritica could be maintained under controlled conditions, which allows growth improvement. Mortality appears to be the limiting factor, but this could be improved by the implementation of efficient culture method, basically oriented to increase the water quality. [source] Growth and reproductive performance of triploid and diploid blacklip abalone, Haliotis rubra (Leach, 1814)AQUACULTURE RESEARCH, Issue 2 2009Wenshan Liu Abstract Growth and reproduction of triploid and diploid blacklip abalone Haliotis rubra (Leach, 1814) were compared in a 30-month study. Triploidy was induced by inhibition of the second polar body formation using 6-dimethylaminopurine (6-DMAP) or cytochalasin B (CB). There were no significant differences in growth and survivorship between triploid and diploid abalone. However, triploid abalone had a more elongated shell and greater foot muscles than diploid abalone. A slightly curvilinear growth in shell length was conformed to all treatments. While diploid abalone had reached sexual maturity and spawned during the study, gonadal development and gamete maturation were abnormal in triploids. Female triploids lacked an apparent gonad at the macroscopic level but microscopic examination revealed that they had a thin layer of oogonia development. In contrast, male triploids were able to form similar-sized gonads to diploids during most of the reproductive period, but with brown-yellow discolouration and stalled gametogenesis at spermatocyte formation. Sex ratio of triploid abalone did not deviate from 1:1. With the onset of sexual maturation, growth and gonadal maturation occurred concurrently in diploid abalone, and there was no indication that growth of (diploid) abalone was reduced. [source] Production of a base population and its responses to F1 selection in the bay scallop, Argopecten irradians irradians Lamarck (1819)AQUACULTURE RESEARCH, Issue 9 2008Haibin Zhang Abstract A base population of the bay scallop, Argopecten irradians irradians Lamarck, was produced by crossing two cultured bay scallop populations. After 1 year of rearing, the top 10% truncation selection of the top 10% (i=1.755) was carried out in the base population of about 1300 adults. A control parental group with a an identical number to the select parental group was randomly selected from the entire population before isolation of the select parental group. The result showed that, at the larval stage, the growth rate of larvae in the selected line was significantly higher than that of the control (P<0.05), and that the genetic gain was 6.78%. Owing to the lower density of control at the spat stage, the mean shell length of the control line was larger than that of the select line at day 100. When the same density was adjusted between two lines in the grow-out stage (from day 100 to 160), the daily growth rate of the selected line was significantly higher than that of the control line (P<0.05). Survival of the select line was significantly larger than that of the control line in the grow-out stage. In conclusion, the results obtained from this experiment indicate that selective breeding from a base population with a high genetic diversity established by mass spawning between different populations appears to be a promising method of genetic improvement in bay scallop, A. irradians irradians Lamarck. [source] Nutritional value of Pavlova spp. (Prymnesiophyceae) for spat of the Cortez oyster Crassostrea corteziensis during late-nursery culturing at the hatcheryAQUACULTURE RESEARCH, Issue 1 2008Josafat J Ojeda-Ramírez Abstract Three Pavlova species were evaluated for their nutritional value as diets for growth and survival of the Cortez oyster Crassostrea corteziensis spat during late-nursery cultivation at a hatchery. Microalgae were provided as monospecific diets (Pavlova salina, P. sp. C50 and P. sp. C53) and in binary combinations of diets 1+2, 1+3 and 2+3 at 80,90 × 103 cells mL,1 for 21 days. Juveniles experienced high survival rates and grew well with all dietary treatments, but binary diets yielded greater survival and growth of spat. From the three binary treatments, Diet 6 (P. sp. C50 and P. sp. C53) promoted significantly (P<0.001) fastest growth of juveniles in shell height (0.19 mm day,1), shell length (0.14 mm day,1), total wet weight (0.04 g day,1) and dry weight of meat biomass (0.024 g day,1). For all shell dimensions, the lowest growth rates occurred with Diets 2 (P. sp. C56 alone) and 3 (P. sp. C50 alone). These results highlight the importance of testing microalgal diets for bivalve spat rather than just relying on published nutritional values. [source] Identification of quantitative trait loci for growth-related traits in the Pacific abalone Haliotis discus hannai InoAQUACULTURE RESEARCH, Issue 8 2007Xiande Liu Abstract The locations and effects of quantitative trait loci (QTL) were estimated for nine characters for growth-related traits in the Pacific abalone (Haliotis discus hannai Ino) using a randomly amplified polymorphic DNA (RAPD), amplification fragment length polymorphism (AFLP) and SSR genetic linkage map. Twenty-eight putatively significant QTLs (LOD>2.4) were detected for nine traits (shell length, shell width, total weight, shell weight, weight of soft part, muscle weight, gonad and digestive gland weight, mantle weight and gill weight). The percentage of phenotypic variation explained by a single QTL ranged from 8.0% to 35.9%. The significant correlations (P<0.001) were found among all the growth-related traits, and Pearson's correlation coefficients were more than 0.81. For the female map, the QTL for growth were concentrated on groups 1 and 4 linkage maps. On the male map, the QTL that influenced growth-related traits gathered on the groups 1 and 9 linkage maps. Genetic linkage map construction and QTL analysis for growth-related traits are the basis for the marker-assisted selection and will eventually improve production and quality of the Pacific abalone. [source] The influence of algal ration and larval density on growth and survival of blacklip pearl oyster Pinctada margaritifera (L.) larvaeAQUACULTURE RESEARCH, Issue 8-9 2000M S Doroudi This paper reports on two factorial design experiments conducted to examine the combined effects of algal ration and larval density on growth and survival of black lip pearl oyster Pinctada margaritifera (L.) larvae. In the first experiment, 1-day-old larvae were cultured for 7 days at densities of 1, 2 and 5 mL,1 and fed algal rations of 0, 2.5, 5 or 12.5 × 103 cells mL,1. In the second experiment, 13-day-old larvae were cultured for 7 days at the above densities and fed algal rations of 0, 7.5, 15 and 37.5 × 103 cells mL,1. Algal rations in both experiments were composed of a 1:1 mixture of the flagellates Isochrysis aff. galbana clone T.ISO and Pavlova salina. Response surface contour diagrams were generated from growth and survival data to estimate optimal culture conditions. Results showed that, within a suitable larval density range, growth of P. margaritifera larvae was significantly (P <,0.01) influenced by algal ration. At the end of the first experiment, greatest survival occurred at a ration of 4.5,11.5 × 103 cells mL,1 and at a larval density of ,,3 mL,1. Greatest antero-posterior shell length was shown by larvae fed between 4.5 × 103 and 11.5 × 103 algal cells mL,1. In the second experiment, greatest antero-posterior shell length occurred within an algal ration range of 15,32 × 103 cells mL,1. The greatest survival occurred below an algal ration of <,2.5 × 103 cells mL,1; however, this algal ration supported poor algal growth. The results indicate that, to maximize growth and survival, P. margaritifera larvae should be fed at an algal ration of ,,8 × 103 cells mL,1 and cultured at a density of three larvae mL,1 up to 8 days of age. Older (13- to 20-day-old) larvae should be cultured at a density of <,2 mL,1 and fed an algal ration of ,,25 × 103 cells mL,1. [source] Growth and production of hatchery-reared juvenile spotted babylon Babylonia areolata Link 1807 cultured to marketable size in intensive flowthrough and semi-closed recirculating water systemsAQUACULTURE RESEARCH, Issue 5 2000N Chaitanawisuti Hatchery-reared juvenile spotted babylon Babylonia areolata (mean initial shell length 12.8 mm) were cultured intensively to marketable size in three 3.0 × 2.5 × 0.7 m indoor canvas rectangular tanks. The duplicate treatments of flowthrough and semi-closed recirculating sea-water systems were compared at an initial stocking density of 300 individuals m,2 (2250 juveniles per tank). The animals were fed ad libitum with fresh carangid fish Selaroides leptolepis once daily. During 240 culture days, average growth rates in shell length and body weight were 3.86 mm month,1 and 1.47 g month,1 for the flowthrough system and 3.21 mm month,1 and 1.10 g month,1 for those in the semi-closed recirculating system. Survival in the flowthrough system (95.77%) was significantly higher than that in the semi-closed recirculating system (79.28%). Feed conversion ratios were 1.68 and 1.96 for flowthrough and semi-closed recirculating systems respectively. [source] Variation in clearance and ingestion rates by larvae of the black-lip pearl oyster (Pinctada margaritifera, L.) feeding on various microalgaeAQUACULTURE NUTRITION, Issue 1 2003M.S. Doroudi Abstract Clearance rate (CR) and ingestion rate (IR) of different sizes (89, 125 and 188 ,m shell length) of Pinctada margaritifera larvae were determined when feeding on various microalgae. The microalgae tested were the diatoms, Chaetoceros muelleri and C. simplex, and flagellates, Tahitian Isochrysis aff. galbana, Pavlova lutheri and P. salina at 5 or 10 cells ,L,1. Both CR and IR of microalgae tested in this study increased with increasing larval size; but at all larval sizes, diatoms resulted in lower CR and IR. Of the microalgae tested, P. margaritifera larvae showed greatest CR and IR with the two Pavlova spp. Maximum CR for P. salina was 10.5, 21.2 and 29.7 ,L h,1 for larvae with shell lengths of 89, 125 and 188 ,m, respectively. The highest IR values for P. margaritifera larvae with shell lengths of 89, 125 and 188 ,m were 8.7, 81.0 and 165.7 cells·larva,1 h,1, respectively. CR and IR of P. salina were approximately five times higher than those recorded for C. muelleri and C. simplex. [source] | |||||||||||||