Grazing Selectivity of Red Abalone Haliotis rufescens Postlarvae on Benthic Diatom Films under Culture Conditions

The gut contents of Haliotis rufescens postlarvae that had grazed on a diatom film grown in PVC buckets were analyzed to determine selectivity in feeding. Species composition and abundances were compared to that of the surrounding film. Diatom samples were oxydized and mounted permanently, or observed directly by the squash technique under phase contrast microscopy. The surrounding flora yielded 111 taxa, while 64 species appeared in the gut contents. A high proportion of Pinnularia biceps v. minor and Navicula incerta (and others) in the gut contents, which were rare or absent from the samples of the surrounding flora, indicated grazing selectivity by the postlarvae. An analysis of similarity confirmed that samples from the gut contents could be grouped together and that they were clearly different from the surrounding flora.     

底栖硅藻种类组成对皱纹盘鲍匍匐幼体和稚鲍生长、存活的影响

为验证由生产培养获得的不同质量的底栖硅藻培养皱纹盘鲍不同生长阶段幼体的效果,采用经不同培养措施获得的两类底栖硅藻群落(饵料A和饵料B)培养皱纹盘鲍前期匍訇幼体和稚鲍.试验结果表明,饵料A培养前期匍匐幼体的存活率[(43.47±13.53)%]显著高于饵料B[(6.94±5.17)%],但生长指标差异不显著.两类饵料培养的稚鲍存活率差异不显著,但饵料B的生长速度和特定生长率[(0.151±0.025)mm/d和(4.706±0.492)%/d)]显著高于饵料A[(0.103±0.022)mm/d和(3.625±0.374)%/d)].说明皱纹盘鲍幼体在不同生长阶段适应底栖硅藻的种类不同.匍匐幼体期对底栖硅藻质量要求较高,稚鲍期由于食量增加和食性转化,对饵料数量的要求表现得更为明显.     

A Growth Assessment of Juvenile Abalone Haliotis laevigata Fed Enriched Macroalgae Ulva rigida

The experiment was conducted to assess the growth of juvenile greenlip abalone Haliotis laevigata fed a range of Ulva rigida diets with different nitrogen contents and an artificial pelleted diet. The minimal nutrient concentration resulting in significant enrichment of U. rigida was 2.25 mg N l^?1. The maximum nitrogen content obtained by U. rigida in this study was 6.099%, which resulted from an inorganic nutrient concentration of 7 mg N l^?1. However, no further significant increase in enrichment occurred from nutrient concentrations of 10 and 15 mg N l^?1. Abalone specific growth rate in shell length (SGR_L) and wet weight (SGR_W) and foot muscle yield were significantly higher for abalone fed the artificial diet compared to those fed any U. rigida diet. Abalone fed U. rigida enriched in less than 15 mg N l^?1 had similar growth rates compared to abalone fed unenriched U. rigida. Abalone fed the artificial diet contributed a higher percentage of weight gain into the valuable foot muscle. The foot muscle moisture content of abalone fed the artificial diet was significantly lower than that of abalone fed any U. rigida diet. The conclusions reached by this study should assist Australian abalone producers in assessing the potential benefits of using U. rigida as an effluent biofilter and subsequent food source for the commercially important juvenile greenlip abalone.     

Effect of Dietary Carbohydrate‐to‐Lipid Ratio on Growth and Carcass Composition of Juvenile Abalone,Haliotis discus,Reeve 1846

The optimal dietary carbohydrate (C) : lipid (L) ratio on growth and carcass composition of juvenile abalone, Haliotis discus, was determined. A total of 1260 juveniles were randomly distributed into 18 containers. Six experimental diets containing different ratios of C to L (49:1, 48:2, 47:3, 45:5, 43:7, and 41:9) were prepared and referred to as the C49:L1, C48:L2, C47:L3, C45:L5, C43:L7, and C41:L9 diets, respectively. Water stability of the experimental diets was measured 12, 24, and 48 h after seawater immersion. Crude protein, L and ash content of the experimental diets decreased with time. Survival of abalone fed the C48:L2 diet was higher than that of abalone fed the C49:L1 and C41:L9 diets. Weight gain and specific growth rate (SGR) of abalone fed the C49:L1, C48:L2, and C47:L3 diets were higher than that of abalone fed the C45:L5, C43:L7, and C41:L9 diets. Crude L content of the soft body of abalone was directly reflected from dietary crude L content. In conclusion, the optimal dietary C : L ratio was estimated to be 48:2 and 47:3 based on survival, weight gain, and SGR of juvenile abalone, respectively. Greater than 3% L content in the diet deteriorated performance of this species of abalone.     

Effect of Feeding Regime on Compensatory Growth of Juvenile Abalone,Haliotis discus hannai,Fed on the Dry Sea Tangle,Laminaria japonica

Effect of feeding regime on compensatory growth of juvenile abalone (Haliotis discus hannai) fed on the dry sea tangle (Laminaria japonica) was determined. Thirty juvenile abalone averaging 15.7 g were randomly stocked into 18 50‐L plastic rectangular containers each. Six treatments were prepared in triplicate: Abalone were fed the dry sea tangle once a day at a satiation level with a little leftover for 16 wk as the control (Con) and other abalone were fed the dry sea tangle once a day at a satiation level with a little leftover for 15 wk after 1‐wk starvation (S1 treatment), 14 wk after 2‐wk starvation (S2 treatment), 13 wk after 3‐wk starvation (S3 treatment), 12 wk after 4‐wk starvation (S4 treatment), and 10 wk after 6‐wk starvation (S6 treatment), respectively. A linear relationship between weight change of abalone and wk of starvation was observed: Y (Weight of abalone) = ?0.17X (Wk of starvation) + 15.89 (R ² = 0.9462) (P < 0.0001). The highest survival of abalone was achieved in the S2 treatment, but not different from that of abalone in the Con, S1 and S3 treatments. Weight gain of abalone in the Con treatment was higher than that of abalone in the S4 and S6 treatments. Abalone fed on the dry sea tangle seemed to be able to achieve full compensatory growth up to 3‐wk starvation.     

Optimizing the Concentration of Gamma-Aminobutyric Acid (GABA) for Inducing Larval Metamorphosis in the Red Abalone Haliotis rufescens (Mollusca: Gastropoda)

Abstract— The induction of larval metamorphosis is a critical step in abalone Haliotis spp . culture. Recently, gamma-aminobutyric acid (GABA) has been used as an inducer by an increasing number of commercial hatcheries, because of its higher efficiency over other settlement methods. The conventional GABA concentration used is 1.0 micromolar as suggested by controlled laboratory experiments. However, poor results are occasionally reported in hatcheries, probably because the bacterial load in commercial systems degrade the inducer to levels below the required threshold. To cope with this problem, GABA concentration might be increased within safe limits to compensate for potential bacterial degradation, but information to adequately support this alternative is missing. This contribution describes two experiments on this issue with red abalone. H. rufescens larvae which suggest that GABA concentration could be increased at least 100% without causing the detrimental effects on metamorphosis induction or postlarval fitness reported for higher toxic levels. The impact of this result on abalone seed production is discussed.     

Low‐density culture of red abalone juveniles,Haliotis rufescens Swainson 1822, recirculating aquaculture system and flow‐through system

Commercial abalone culture is carried out using flow‐through systems with a high water volume exchange in Baja California, Mexico. The objective of this work was to compare the growth rate and survival of red abalone cultured in two systems. Flow through (daily water exchange rate of 800%) and recirculating systems consisted of a 250 L fibreglass tank and constant aeration, but biofiltration in the recirculating system was provided with a 28 L (1 ft³) bubble‐washed bead filter. Water variables were measured either daily (dissolved oxygen, temperature, pH and salinity) or three times a week (total ammonia nitrogen, nitrate‐nitrogen, nitrite‐nitrogen and alkalinity). Shell length was measured every 2 weeks for 18 weeks. Only the alkalinity and pH were significantly different due to the addition of sodium bicarbonate to the recirculating system. Abalone growth rate was 26.1 ± 15.96 μm day^?1 in the recirculating systems and 22.21 ± 18.69 μm day^–1 in the flow‐through systems. The final survival was 78.74% in the recirculating systems and 71.82% in the flow‐through systems. Significant differences in the final size and survival of the abalones were found between systems (P<0.05). Therefore, recirculating aquaculture systems is a feasible alternative for juvenile red abalone culture.     

中国海耳鲍成熟卵的超微结构

利用光学和电子显微镜对耳鲍排出体外成熟卵的形态及超微结构进行了观察。耳鲍成熟卵具有卵胶质膜、卵黄膜和细胞膜;卵质中含有线粒体、核糖体、内质网及高尔基体等细胞器;还含有高电子密度的分泌颗粒和吞饮小泡。皮层中含有皮质小泡,但未发现中心粒。耳鲍成熟卵没有明显的卵极标志,卵黄颗粒分布较均匀。     

Effects of Algae and Shell Pigment Extract‐supplemented Diets on Shell Pigmentation and Growth Performance of Pacific Abalone,Haliotis discus hannai

To improve shell pigmentation and growth performance of Pacific abalone, five extruded diets were prepared by supplementing a formulated control diet with 3% each of three species of algae (Pacific dulse, Porphyra yezoensis, Spirulina) and a pigment extract from the abalone shells (0.02%). Each of the five diets and a commercial feed were randomly assigned to three containers each stocked with 1000 juvenile Pacific abalone (2 g per individual) in a flow‐through seawater system for a 5‐mo feeding trial. Test results showed: (1) all the supplements significantly (P < 0.05) increased percentages of dark‐brown shelled abalone in the test treatments, relative to the control treatment; (2) the abalone fed the experimental diets achieved significantly (P < 0.05) greater final weight, shell‐length growth rates, and higher meat protein contents than those fed the commercial feed (P < 0.05); and (3) the abalone fed the Spirulina‐supplemented diet achieved the best overall growth, pigmentation performances, and feed conversion ratio; and the Pacific dulse supplement generated the highest protein content in abalone meat product (P < 0.05) among the tested diets. These results demonstrate the potential of locally made feed, which can generate desirable characteristics in abalone under aquaculture conditions.     

Effects of Feed Type and Temperature on Growth of Juvenile Abalone,Haliotis discus hannai Ino

Effects of feed type and temperature on growth and body composition of juvenile abalone, Haliotis discus hannai Ino, were determined. A 2 (feed types: formulated diet and dry sea tangle) × 3 (temperature conditions: 20, 23 and 26 C) factorial design with triplicate was used. Seventy juvenile abalone averaging 4.7 g were randomly distributed into each of 18, 50‐L plastic rectangular containers. Six containers were placed into each temperature condition of three 1.3 ton concrete flow‐through raceway systems. Abalone were daily fed with either the formulated diet or dry sea tangle once a day to satiation level. Survival was affected by feed type, but not by temperature. Weight gain of abalone was affected by both feed type and temperature. Regardless of temperature, weight gain of abalone fed the formulated diet was better than that of abalone fed the dry sea tangle. Shell length and width were affected by feed type, but not by temperature. In conclusion, weight gain of abalone was affected by both feed type and temperature, but feed type had a stronger effect than temperature. The formulated diet achieved better growth of abalone than the dry sea tangle regardless of temperature and 20 C seemed to be recommendable for abalone among temperature tested.     

不同卵色皱纹盘鲍(Haliotis discus hannai)幼鲍的生长与免疫比较

随机选取100只经过480 d养殖的3♀×10♂绿卵全同胞家系子一代(F1)的皱纹盘鲍(Haliotis discus hannai)幼鲍为实验材料,进行雌雄、卵色分类后,测量所有样本总重、壳长、壳宽等生长指标,并测定不同卵色幼鲍的超氧化物歧化酶(SOD)、碱性磷酸酶(AKP)、酸性磷酸酶(ACP)、过氧化氢酶(CAT)和溶菌酶(LZM)的活性,进行单因素方差分析(One-way ANOVA).结果显示,在生长方面,不同卵色幼鲍的各生长指标无显著差异(P＞0.05),但绿卵幼鲍的各生长指标均高于其他3种卵色;在免疫酶活性方面,4种卵色幼鲍在SOD和CAT活性上无显著差异(P＞0.05),绿卵幼鲍的AKP、ACP和LZM 3种酶的活性与棕色和棕红色卵幼鲍存在显著差异(P＜0.05),而与棕绿色卵幼鲍无显著差异,其酶活性从高到低按卵色排列依次为绿色、棕绿色、棕色和棕红色.上述研究结果可为利用卵色选育皱纹盘鲍高产抗逆新品系提供依据.     

Free Amino Acid and Nucleotide Concentrations in New Zealand Abalone (Paua), Haliotis iris,Fed Casein-Based,Macroalgal, or Wild Diets

Abstract

Paua (Haliotis iris) were fed either a commercial casein-based diet, macroalgae, or were fasted. The meat quality of these animals was evaluated over a period of 6 months by measuring tissue nucleotides, including the high-energy phosphate compound adenosine triphosphate (ATP), and free amino acids which contribute to both protein composition and taste quality. Makara(tm) -fed paua had high ATP levels comparable with those in the wild, and their glycine component was 2-3 fold higher. The amino acid taurine, which occurs in high concentrations in red algae, is not incorporated into protein in paua, but plays a critical role in the metabolism of abalone. All paua maintained appreciable taurine content.     

Alternative Protein Sources in Artificial Diets for New Zealand's Black‐Footed Abalone,Haliotis iris,Martyn 1784, Juveniles

Growth and health parameters were tested in juvenile New Zealand black‐footed abalone, Haliotis iris, fed nine diets containing different protein sources (white and red fishmeal, blood meal, meat and bone meal, casein, soybean concentrate, wheat gluten, maize gluten, and Spirulina powder) over a 5‐mo period. The growth parameters measured included shell length, total animal weight, and soft body and gonad weights. The health indicators included survival, goblet cell counts, and epithelium thickness of the tentacle region. Proximate analyses and amino acid and fatty acid profiles were also determined on the diets, soft body tissues and shell materials to evaluate the nutrient contents (diet and animal) and requirements (animal). Measurements of soft body, gonad, and shell growth parameters indicated that white and red fishmeals generally result in better growth. Animals fed blood meal had the lowest survival rates and crude protein contents. Spirulina produced animals with the heaviest shells and soybean treatments produced animals with the highest gonad to soft body ratios. Significantly lower acid/basic amino acid ratios were found in fishmeal diets, indicating that animals fed fishmeal may incorporate more aragonite than calcite in their shells.     

Factors influencing half‐pearl (mabe) production and quality in the red abalone Haliotis rufescens

The factors influencing half‐pearl (mabe) production in the red abalone Haliotis rufescens were investigated, as a strategy to optimize the technology for the development of a pearling industry in Chile. The effects of abalone size (small, large), implant position (dorsal, central, ventral and their combinations), and number of nuclei (one, two, three) were analysed on the quantity, thickness of the nacre layer and quality (shape, colour, lustre, defects) of the mabe produced. The size of abalone did not exert a clear influence on the quantity and quality of mabe, but the position on the shell (firstly) and number of nuclei (secondly) did. More mabe, with thicker nacre, brighter lustre and fewer defects occurred in small or large abalone implanted with only one nucleus on dorsal position. In contrast, small and large abalone implanted in the ventral position formed less mabe, with thinner nacre, poor lustre and more defects. This likely occurs because mantle tissue folds at the ventral position and does not always cover the nucleus, leaving it partially or totally exposed. Most of the pearls were categories AA in small abalone and A in large abalone; only three AAA gems were produced in large abalone with one nucleus on dorsal position or with three nuclei (DCV). Based on these results, we recommend implanting abalone at 60–100 mm shell length, with only one nucleus on the dorsal position.     

An Assessment of Hatchery Cohort Growth Rates of South African Abalone,Haliotis midae,Across Four Commercial Environments

The abalone, Haliotis midae (commonly referred to as “perlemoen”), is an important aquaculture species in South Africa, accounting for the highest percentage of total aquaculture production revenue. The industry largely makes use of wild, undomesticated broodstock and thus a consortium of top producers was formed to develop a genetic improvement program to increase efficiency and sustainability of the industry. As such, the current study aimed to evaluate growth trait performance (wet weight and shell length) of four hatchery‐derived cohorts of South African abalone, across four differing production environments. No significant cohort‐by‐location effects were found for weight and length traits; however, differences were detected between respective cohorts and locations. It is concluded that a single synthetic population comprised of all hatchery cohorts under a single breeding goal is suitable for production at all test locations. Furthermore, advances in artificial reproductive technologies, genetic markers, and individual identification hold promise for genetic improvement of the species.     

Pathogenesis of vibriosis in cultured juvenile red abalone, Haliotis rufescens Swainson

Abstract. Morbidity of intensively cultured red abalone, Haliotis rufescens , as well as experimentally stressed (elevated temperature and hyper-oxygenation) abalone, was studied using clinical, histological, immunofluorescent and bacteriological techniques. Histological study showed a typical pattern of bacterial infection from all groups studied, characterized by epithelial exfoliation or rupture and systemic growth of the bacteria along vascular sinuses and along neural sheaths. Peripheral neurons degenerated rapidly and a responsive host cellular infiltrate did not appear to effectively retard the advancement of the infection. Nine bacterial isolates from the culture system water or sick animals were characterized biochemically. All were Gram-negative, facultatively anaerobic, non-aerogenic, oxidase-positive rods with single polar flagella and thus appeared related to the Vibrio group. Further characterization showed that most isolates did not correspond to specifically characterized vibrios, Antiserum prepared to the isolates contained antibody both to common group antigens (from all nine strains) and to strain-specific antigens. Selection of antiserum and subsequent absorption permitted the use of the antiserum for specific recognition of each isolate. Immunofluorescent studies clearly demonstrated that antiserum to an isolate corresponding to Vibrio alginolyticus was the predominant antiserum producing positive staining of infecting bacteria in the typical lesions in abalone tissues. The pattern of positive staining corresponded to histopathological observations of the disease. The disease can be managed in husbandry systems by both limiting the number of potentially pathogenic bacteria and by limiting the exposure of the animals to physico-chemical stresses.     

Hybridization between Haliotis rufescens and Haliotis discus hannai: evaluation of fertilization,larval development,growth and thermal tolerance

Two introduced abalone species are currently produced in Chile, red abalone Haliotis rufescens and Japanese abalone Haliotis discus hannai. However, red abalone accounts for 99% of total production, while the Japanese abalone has not adapted well to Chilean coastal waters. This study reports the hatching, growth and thermal tolerance performance in interspecific hybrids produced between red (R) and Japanese (J) abalone. Our results show that egg age and sperm concentration were critical factors to produce hybrids. The cross R♀ × J♂ showed a fertilization rate of 55.3 ± 3.5% using 20‐min‐old eggs and sperm concentrations of 14 × 10⁶ cells mL^?1, while the reciprocal cross (J♀ × R♂) was not successful. Further, larval development stages were similar in RR, JJ and RJ hybrid abalones. Among the experimental trials, settlement rate varied from 12.3% to 18.6% and final survival from 20.1% to 31.7%, being the RJ hybrid rates intermediate between parental species. The final shell lengths were similar between RR and RJ hybrids, but significantly higher in JJ abalones. In addition, thermal tolerance was ascertained due its pivotal role for the abalone physiology. Thus, RJ hybrids showed the highest HSP70 gene expression and offers new possibilities to expand Chilean abalone production in warm waters zones.     

Histological evidence of accumulation of iron in postlarvae of red abalone,Haliotis rufescens

The effect of iron on abalone postlarvae (Haliotis rufescens) was investigated in a controlled‐culturing system. Three iron concentrations (0.15, 1.5 and 15 mg L^?1 of Fe) and a control (no iron added) were used to culture H. rufescens postlarvae while being fed the diatom Navicula inserta over 10 days. Results indicate that H. rufescens postlarvae accumulate iron granules in the stomach, digestive gland and mantle, but not in the gills or other tissues. The number and diameter of iron granules in tissues increased with increasing iron concentration in the culturing environment. The iron accumulation is assumed to have been acquired in the digestive system through the iron‐enriched diatom feed and in the mantle through subcutaneous iron transfer. The lack of iron granules in the gills suggests that iron is not absorbed through the respiratory system, as is the case for many filter feeding bivalves. Exposure to the highest iron concentration (15 mg L^?1) resulted in tissue abnormalities where granules accumulated, and may have significantly affected the health of H. rufescens postlarvae. These findings provide valuable information for the regulation of appropriate iron levels within aquaculture settings and highlights the importance of monitoring iron levels within abalone larval culturing environments.     

Feces Production and Ammonia Excretion of Pacific Abalone,Haliotis discus hannai,Fed Kelp,Laminaria japonica,in Relation to Water Temperature and Shell Length

Nitrogen excreted by aquatic animals mainly takes the form of metabolic wastes such as feces and ammonia, which is accumulated in the intensive aquaculture system and causes serious environmental contamination. So it is very important to determine the waste excretion characteristics of aquatic animals for the development of practical and nonpolluting land‐based aquaculture. Abalone has a unique feeding habit and feeding regime, different from those of finfish; abalone gnaw feed seaweed to produce feces and ammonia continuously. In this study, the rates of feces production and ammonia excretion of pacific abalone, Haliotis discus hannai, of three shell lengths (3, 5, and 7 cm) were investigated under three different temperature conditions (12, 16, and 20 C). All experiments were performed in triplicate in a semirecirculating aquaculture system. Feces were collected for 5 d, and ammonia concentrations (total ammonia nitrogen [TAN]) in the tank inlet and outlet were monitored every 4‐h interval for 24 h at the fourth day of the feces collection. The regressions for the weight‐specific feces production rate (g feces/kg abalone/d) and the weight‐specific TAN excretion rate (mg TAN/kg abalone/d) in relation to water temperature (T, C) and shell length (L, cm) were weight‐specific feces production rate = exp(1.575 ? 281.2/T² – 0.142L), r² = 0.9550, and weight‐specific TAN excretion rate = exp(5.052 ? 277.1/T² ? 0.136L), r² = 0.9598. Pacific abalone produced 108.3–111.7 g feces and excreted 3.83 g TAN/kg seaweed ingested (dry weight).     

Histopathology of oxygen intoxication in the juvenile red abalone, Haliotis rufescens Swainson

Abstract. Juvenile abalone were exposed to supersaturated oxygen conditions (about 150–200% of saturation) in order to reproduce similar conditions encountered in intensive husbandry systems and to then study the resultant lesions. Depigmentation, lethargy and swelling of tissues were observed clinically. Histopathology showed that the cytoplasmic vacuoles of large haemocytes were enlarged. Oxygen emboli were observed throughout the muscular tissue and connective tissue but separation of fibrous neural sheath from nerve cell bodies and surrounding tissue was the predominant lesion. Chromatin of the nuclei of nerve cells became marginated. Gaseous emboli were observed at various other locations in the vascular system. At termination of the experiment all animals sampled bacteriologically showed systemic infection with Vibrio alginolyticus . The clinical signs appeared to result from mechanical interference caused by the accumulation of oxygen and from dysfunction of neural structures. The predominant histopathological changes occurred after only 3 h or less exposure time. Normal histology of the haemocytes and nerve structures is described.