Ezo Abalone Haliotis Discus Hannai Research Articles

Fenton reaction as a possible stimulus to induce spawning in Ezo abalone Haliotis discus hannai during stormy weather

Synchronous spawning is an important behavior which increases fertilization success of invertebrates with external fertilization. Previous work has shown that free radicals can induce spawning behavior in tank experiments, but the stimulus for spawning in the wild is not fully understood. Ezo abalone Haliotis discus hannai mainly spawn during stormy weather. Rainwater contains H2O2 and iron (II) ions (Fe2+). We propose that during stormy weather, water layers in the ocean are mixed and the surface layer containing H2O2 and Fe2+ interacts with the ocean bottom; this leads to conditions suitable for the occurrence of the Fenton reaction (wherein Fe2+ ions are oxidized to iron [III] ions by H2O2, and ·OH and hydroxide ions are generated). Hydroxyl radicals (·OH) are generated during the oxidization of Fe2+ by H2O2, and we hypothesized that these induce spawning behavior of abalone in the wild. We observed that H. discus hannai released eggs after salinity decreased as a result of rainfall during stormy conditions. In addition, a tank experiment demonstrated that ·OH generated by the Fenton reaction induced synchronous spawning behavior between the sexes. This study provides a new hypothesis about control of synchronous spawning in H. discus hannai, and the results might be applicable to other invertebrates.

Effects of mucus trail following on the distance between individuals of opposite sex and its influence on the evolution of the trait in the Ezo abalone Haliotis discus hannai.

BackgroundAggregation affects the fertilization rate of species that utilize external fertilization. However, the process of aggregation has not been studied in detail, using either theoretical models or real world observations. We used the Ezo abalone Haliotis discus hannai as a model animal species to evaluate whether mucus trail following (MTF) facilitates aggregation by reducing the distance between members of opposite sexes. We also examined whether the fertilization rate increase with mucus-trail-following is an evolutionary driving force in mucus following behavior.MethodsWe used a y-maze to test whether H. discus hannai follows the mucus trails of other individuals. Distances between members of the opposite sex of MTF individuals were compared to non-MTF individuals using an individual-based model (IBM) consistent with the behavior of H. discus hannai. To examine whether MTF behavior evolved to reduce distances between members of the opposite sex, we constructed simple population genetic models of a diploid population with nonoverlapping, discrete generations.ResultsHaliotis discus hannai chose the y-maze arm with the mucus trail more frequently than the one without, regardless of the sex of the abalone that secreted the mucus or the reproductive season. In the IBM the distance between opposite sexes was significantly reduced by MTF behavior; however, the difference in distances between opposite sex compared to same sex individuals was only several centimeters. Simple population genetic models indicated that the aggregating effect of MTF between the opposite sex members could be an evolutionary driving force.ConclusionsThese results suggest that observed MTF behavior might have evolved as a mechanism to increase the fertilization rates although other factors could also be involved.

A Study on the Comparative Analysis of Business Performance of Abalone Seed, Haliotis discus hannai by Region and Farming Size in the Land-based System

This study is aimed comparative analysis for business performance of land-based ezo abalone (Haliotis discus hannai) seed farms by standardizing cost structures by region and farming size. The result of survey on average farming incomes by region showed that farming incomes in Haenam and Jindo regions were much higher than those in other regions. Followed by Wando region, incomes in other regions were analyzed to be relatively lower. It is shown that farming incomes became higher as farm size increased. Farming incomes per unit size which were modified from farming incomes by region were highest in Jindo region, followed by East sea region, Wando and Haenam regions. Incomes in Jeju and Yeosu regions were analyzed to be relatively lower. Results on farming incomes per unit size () showed that both farming incomes and profits became higher as size increased. It implies that a scale effectiveness might exist in case of land-based abalone culture system. Impacts of major factors on farming profits and returns on investment in abalone seed aquaculture are summarized as follow. First, only if the survival rate increased by 10% with improvement of component ratio, variable effects became largest. In variable effects of other factors, a variation in Jindo region was largest and on the other hand, a variation in Yeosu region was shown to be smallest.

10. 北海道におけるエゾアワビ人工種苗放流による親密度増加が加入量に及ぼす効果について

10. 北海道におけるエゾアワビ人工種苗放流による親密度増加が加入量に及ぼす効果について

4. 北海道の磯焼け海域における群集構造の特徴とエゾアワビの再生産へ及ぼす磯焼けの影響

4. 北海道の磯焼け海域における群集構造の特徴とエゾアワビの再生産へ及ぼす磯焼けの影響

3. エゾアワビの成熟に及ぼす餌料の質・量の影響

3. エゾアワビの成熟に及ぼす餌料の質・量の影響

6. エゾアワビの異なる繁殖形態による加入機構の比較

6. エゾアワビの異なる繁殖形態による加入機構の比較

Effects of elevated pCO2 on the early development of the commercially important gastropod, Ezo abalone Haliotis discus hannai

We used an up-to-date, a high accuracy CO2 manipulation system to investigate the sensitivity of organisms to CO2 acidification, rearing marine calcifiers under elevated CO2 in running water. We evaluated the effects of elevated partial pressures of carbon dioxide (pCO2) in seawater on larvae of the commercially important marine gastropod Ezo abalone Haliotis discus hannai. In larval Ezo abalone, no effect of exposure to <1100 μatm pCO2 seawater was observed in fertilization, malformation, or mortality rates until 15 h after fertilization. However, compared to control larvae in seawater (450 or 500 μatm pCO2), the fertilization rate and the hatching rate (15 h after fertilization) decreased with increased pCO2 exposure (1650 and 2150 μatm pCO2) and the malformation rate increased significantly, with the larval shell length being smaller 75 h after hatching. These results suggest that ocean acidification will potentially impact the marine population of Ezo abalone as a human food source in the future.

Immunohistochemical observations of vitellin synthesis and accumulation processes in ovary of Ezo abalone Haliotis discus hannai

Ovarian follicle cells are the site of yolk protein synthesis in the Ezo abalone Haliotis discus hannai. In this study, histological observations of ovarian follicle cells were conducted in H. discus hannai by immunocytochemical and in situ hybridization methods focusing on their function of yolk protein synthesis. An antibody raised against purified yolk protein (vitellin, Vn) recognized yolk granules in oocytes, and ovarian follicle cells adjacent to the oocytes under yolk accumulation were stained positively with both anti-Vn antibody and an antisense probe for vitellogenin (the precursor for vitellin, Vtg) mRNA. These results indicate that the abalone Vtg gene is transcribed and translated in the ovarian follicle cells. In oocytes in the early phase of yolk accumulation, positive reactions with the antibody appeared first in the stalk part, and the follicle cells adjacent to the stalk were also stained positively. These observations imply local transport of yolk protein from the follicle cells to the oocyte through an extracellular space around the oocyte stalk. Ovarian follicle cells changed their morphological characteristics and reactivity to the antibody in close relation to the stages of the adjacent oocyte, which suggests the presence of functional interactions between follicle cells and oocytes in the course of yolk protein synthesis and accumulation.

Estimating larval supply of Ezo abalone Haliotis discus hannai in a small bay using a coupled particle-tracking and hydrodynamic model: insights into the establishment of harvest refugia

Most juveniles of Haliotis discus hannai have been found to be descendants of wild individuals, although most adults were artificially produced (released) individuals as a result of restocking inside the refugium located near the head of Oshoro Bay, Hokkaido, Japan. To estimate the larval supply from released and wild individuals into the refugium and to compare the suitability of locations as larval sources, we simulated larval dispersal using a coupled hydrodynamic and particle-tracking model. The simulation results indicated that more larvae may be supplied from the wild adults inside the bay to the refugium than from the released adults. These results are consistent with the observed high abundance of wild juveniles in the refugium. Most larvae from the refugium were predicted to disperse out of the bay. We found that larval retention in the bay was at least one order of magnitude higher than that in the refugium. Thus, it may be more effective in terms of self-replenishment and reproduction if the refugium were to be expanded to the bay scale. There were only minor differences among the compared sites at the head of the bay in terms of their suitability as larval sources. Consequently, the establishment of new refugia in this area could be expected to provide an effectiveness equal to that of the current refugium.

Overwinter mortality of young-of-the-year Ezo abalone in relation to seawater temperature on the North Pacific coast of Japan

The Ezo abalone Haliotis discus hannai is the only species of abalone inhabiting the coastal waters affected by the cold Oyashio current in the Pacific waters of northern Honshu, Japan. Overwinter mortality of young-of-the-year (YOY) Ezo abalone was examined for 2000, 2001, and 2003 to 2006 year classes in Kadonohama Bay, northern Japan, to test the hypothesis that winter sea- water temperature controls recruitment fluctuation of this northernmost abalone and regulates their distribution limit. Eggs of Ezo abalone hatch between late summer and mid-autumn, and grow to a size of 2 to 8 mm in shell length by winter. Overwinter mortality rates varied among years (range: 0 to 97.4%), and there was a strong negative relationship between the instantaneous mortality rate and the winter temperature. High mortalities of YOY abalone were observed in February 2001 and March 2006, respectively. In both cases, the Oyashio current extended south to the study area, and the mean temperature fell to below 5°C. High mortalities were not observed in the other years when the mini- mum temperatures were higher than 6°C, as the Oyashio current did not extend to the study area. The differences in shell length between early winter and post-winter suggest that the low tempera- ture tolerance of YOY abalone may be size-dependent. Although not conclusive, the winter seawater temperature is an important factor affecting the survival of YOY and is the principal factor for the variation in the recruitment of Ezo abalone and the limit of their northward distribution.

DEVELOPMENT AND CURRENT STATUS OF ABALONE AQUACULTURE IN CHILE

Abalone aquaculture is rapidly developing in Chile although this mollusc does not occur naturally in this country. The red abalone Haliotis rufescens was introduced in 1977 and the ezo abalone Haliotis discus hannai in 1982. After several years of research and development, the industry began in 1992 and Chile is currently the fifth producer of cultured abalone in the world with 304 tons in 2006. Twenty five companies are involved in this Chilean industry, culturing mainly red abalone. Most of the farms in the North include hatcheries and land-based grow-out operations, whereas most of the in-water grow-out facilities are located in the South. All farms in Chile use algae as the main food for growing abalone, but artificial feeds are also used in some land-based operations in the North. The average size of abalone harvested in Chile is 8 cm (100-120 g) after 3-5 y in culture systems. Whole frozen abalone (shell on) is the most important form of this Chilean product (82% in 2006) and the main market is Japan (90.2%). Abalone production has increased at a rate of around 50% per annum over the last 3 y. This development is expected to continue in the next years, fostered by favorable geographic, economic, and environmental conditions as well as an important government support to invest in abalone. A survey among producers revealed that feed availability and quality is currently considered a key issue to further develop this industry in Chile.

Effect of tremata closures on the oxygen consumption rhythm of ezo abalone Haliotis discus hannai

Cultured adults of ezo abalone, Haliotis discus hannai (shell length, 89.3 ± 6.4 mm and flesh dry weight, 13.0 ± 1.6 g; n = 12) were exposed to different temperatures (10 and 25 °C) to determine whether respiration effects were induced by artificial closure of the second and third tremata (respiratory pores). A respirometer was used to determine the oxygen consumption rates (OCRs) as measures of metabolic activity. The closed tremata were the second and third of the four open tremata anterior to the head of the abalone. The OCRs of starved abalone were measured under constant conditions (CC: constant dark and constant temperature) during a 240-h period, consisting of 120 h before and 120 h after the closure of tremata. The endogenous rhythm of the OCRs in cultured ezo abalone exhibited a dominant circadian rhythm (unimodal rhythm) in the latter half of the experimental period and occasionally showed a weaker but similar circatidal rhythm (bimodal rhythm) in the first half of the experimental period regardless of temperature. The results from the present study indicate that the rhythmicity of the OCRs in starved abalone is not affected by closure of the second and third tremata. This study offers essential physiological information for utilizing tremata in developing a tagging technique in abalone.

Mass Mortality of Japanese Abalone Haliotis discus hannai Caused by Vibrio harveyi Infection

Sixty thousand of deaths among cultured Ezo abalone Haliotis discus hannai occurred within a few days at an abalone farm in Japan in the middle of August, 2002. Dead animals were characterized by a hemolymphatic edema around the major circulatory system. Vibrios showing swarming motility dominated in the edema. The pathogenic vibrios were identified as Vibrio harveyi based on a phylogenetic analysis and a phenotypic characterization. In both immersion and injection experiments, the swarming vibrios fulfilled Koch's postulates as a pathogen for Ezo abalone. Using a GFP-tagged V. harveyi S20, a clump of bacterium was detected on the gills of the abalone within 48 hours after contact with the bacterium. This is the first report of V. harveyi infection in Ezo abalone Haliotis discus hannai.

岩手県におけるエゾアワビの種苗放流効果

岩手県におけるエゾアワビの種苗放流効果

Microsatellite DNA markers of Ezo abalone ( Haliotis discus hannai): a preliminary assessment of natural populations sampled from heavily stocked areas

Reproductive success of released animals becomes a growing interest in the context of stock enhancement program and conservation biology. In the case of the Ezo abalone (Pacific abalone; Haliotis discus hannai), limited information is available about the extent of interbreeding between natural and released hatchery populations. This study aimed to develop microsatellite DNA markers from Ezo abalone to address the issue. We developed 38 microsatellite markers that worked well in three full-sib families established from wild caught abalone. Of these, nine markers, with which alleles could be scored easily and accurately, were applied to two population samples derived from coastal areas where intensive releases of hatchery-produced abalone seedlings have been carried out. Multilocus estimates of genetic population differentiation calculated based on the nine markers ( F ST analogue θ and R ST analogue ρ) rejected a null hypothesis of genetic homogeneity between the populations ( θ=0.048, P<0.00001; ρ=0.029, P=0.0051). Although both populations conformed to Hardy Weinberg's equilibrium at almost all of the nine loci, the results of simulation analysis for variance of relatedness coefficient provided evidence of nonrandom mating in each population, possibly caused by the cumulative effect of stocking on the genetic make-up. The population analysis presented here is preliminary; but we consider that the microsatellite markers are potentially an efficient means to examine the reproductive contribution of released abalone to natural resources.

Purification and Characterization of a Novel Extracellular .BETA.-1,3-Glucanase Produced by Bacillus clausii NM-1 Isolated from Ezo Abalone Haliotis discus hannai.

A novel extracellular alkaline stable β-1,3-glucanase produced byBacillus clausii NM-1 isolated from the ezo abaloneHaliotis discus hannai was purified by ammonium sulfate precipitation, DEAE-Sepharose FF ion exchange chromatography and Sephacryl S-200HR gel filtration. The molecular weight of the purified enzyme was estimated to be 71 kDa from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme was very stable at pH 5.3 to 11.5 but unstable at pH 4.0 to 4.5. The optimum temperature and thermostability of the enzyme increased in the presence of CaC1, The enzyme hydrolyzed R-1,3-glucan from marine organisms, but did not show activity against any other β-1,3-glucans. The major hydrolysis products of β-1,3-glucan fromLaminaria digitata andEisenia bicyclis were laminaritriose and laminaritetraose, respectively. The N-terminal amino acid sequence of the purified enzyme was similar to that of several β-1,3-glucanases in the glycoside hydrolase family 16.

コンブ科褐藻数種のエゾアワビに対する摂食阻害活性

Feeding-deterrent activities of the methanol extracts from the brown algae of the family Laminariaceae, Ecklonia cava, E. kurome, Laminaria japonica, L. religiosa, L. angustata, and L. angustata var. longissima, were tested on the ezo-abalone Haliotis discus hannai by a bioaasay with the cellulose plate method. Three phlorotannin-rich fractions from the methanol extracts of E. cava and E. kurome, which are perennial algae, showed potent feeding-deterrent activity as in the cases of E. stolonifera and Eisenia bicyclis. On the other hand, none of the fractions from the methanol extracts of four Laminaria species, which are annual algae, showed any significant feeding-deterrent activity as in the cases of Eckloniopsis radicosa. Among four perennial species, the feeding-deterrent activities are, in order of effectiveness, E. stolonifera, E. kurome, E. cava, and Eisenia bicyclis, this being in reciprocal proportion to their size. It was concluded that laminariaceous algae have a chemical defense mechanism against marine herbivores, which adaptively depends on the rate of algal growth and size.