Response of riparian vegetation to the removal of the invasive forb,Solidago gigantea,and its litter layer

In order to explore the methods of recovering native grasses into exotic vegetation, the response of riparian vegetation to the removal of the above‐ground shoots and/or litter of Solidago gigantea in a flood plain in Hokkaido, northern Japan, was investigated. The four treatments were: the removal of the above‐ground shoots of S. gigantea (A); the removal of the litter of S. gigantea (L); the removal of both the above‐ground shoots and litter of S. gigantea (AL); and a control (C). The vegetation cover and S. gigantea cover decreased in the A and AL treatments and increased in the L and C treatments. The understory plant cover increased in the A and AL treatments, but did not change in the L and C treatments. The increases in the understory cover in the A and AL treatments were associated with increases in Phalaris arundinacea. The seedling emergence of P. arundinacea was promoted by AL. In a greenhouse, the S. gigantea litter tended to decrease the seed germination of P. arundinacea. The AL treatment also increased the abundance of the other exotic plant, Solidago altissima. The continuous removal of the above‐ground shoots and litter of S. gigantea long term is effective for promoting the recovery and emergence of native riparian grassland vegetation. However, this method also promotes the recovery of other exotics.     

Primary Study on Experiment of Tetraploid Induction in Haliotis discus hannai with PEG

The experiment was performed on induction tetraploid of Haliotis discus hannai at two-cell stage through cell fusion with PEG treatment. In this paper, the orthogonal experiment of three factors and three levels [L9 (34)] was used. Three factors and three levels were molecular weight of PEG: 8 000, 6 000, 4 000 mol·g-1; PEG concentration: 45%, 50%, 55%; treatment duration time: 1, 2, 3 min, respectively. The results showed that the optimal pattern of three factors and three levels on inducing tetraploid of Haliotis discus hannai at two-cell stage through using PEG treatment were: molecular weight 4 000, concentration 55%, treatment duration time: 2 min. The highest tetraploid induction rate was 10.8% at embryo period. The three factors treatment sequence was treatment duration time→concentration→molecular weight.     

九孔鲍鱼病毒病的防治试验

在福建东山个发病的鲍鱼养殖场进行了对比试验。该种病毒病可通过隔离,使用沙滤水,用鲍毒清药浴或将药拌入产而得到治疗并控制其蔓延。对照池的鲍鱼未采取防治措施短时间内全部死亡。     

Octopus as predators of abalone on a sea ranch

This study examined the occurrence of octopus across an abalone, Haliotis laevigata, Donovan, sea ranch in south‐western Australia, to understand how octopus may be impacting abalone production. Commercial divers removed 654 octopus and 17,666 empty abalone shells during regular, 2 to 4‐weekly surveys over 27 months. A negative binomial generalised linear model estimated a 78% increase in empty shells per artificial abalone habitat per day, when octopuses were present, after adjusting for location and season. Of the 408 shells examined for evidence of predation, 19% had a small, slightly ovoid hole consistent with those made by octopus. The mean (± 1 SE) length of shells with boreholes (70.3 ± 2.2 mm) was significantly longer than those without (59.8 ± 0.5 mm), and boreholes were concentrated over the adductor, respiratory organs and heart. This study provides important insights into the adaptable feeding regimes of octopus and their potential to impose strong top‐down controls on sea ranching operations.     

Substitution effect of Undaria pinnatifida with citrus (Citrus unshiu,Marcovitch) peel by‐product in feed on the growth,body composition and air exposure stressor of juvenile abalone (Haliotis discus,Reeve 1846)

Substitution effect of Undaria pinnatifida with citrus peel by‐product (CPB) on growth, body composition and air exposure stressor of abalone was determined. A total of 1,080 abalone were distributed into 18 net cages. Five formulated diets were prepared in triplicate. The CPB0 diet contained 200 g/kg U. pinnatifida. The 250, 500, 750 and 1,000 g/kg U. pinnatifida were substituted with the equal amount of CPB, referred to as the CPB250, CPB500, CPB750 and CPB1000 diets, respectively. Finally, dry U. pinnatifida was prepared. Abalone were fed for 16 weeks and then subjected to air exposure stressor for 24 hr. The cumulative mortality of abalone was monitored for the following 4 days after 24‐hr air exposure. Survival, weight gain and specific growth rate (SGR) of abalone fed all formulated diets were greater than those of abalone fed the U. pinnatifida. The greatest weight gain and SGR were achieved in abalone fed the CPB500 diet. The chemical composition of the soft body of abalone was not affected by the experimental diets. Higher cumulative mortality was observed in abalone fed the CPB0 and dry U. pinnatifida at 16 hr after 24‐hr air exposure compared to abalone fed all other diets. In conclusion, U. pinnatifida could be completely substituted with CPB in abalone feed.     

Influences of dietary antimicrobial peptide APSH‐07 on the growth performance,immune response and vibriosis resistance of abalone Haliotis discus hannai Ino

A 115‐day feeding trial and subsequently a 10‐day challenge test with Vibrio parahaemolyticus were conducted to investigate the effects of dietary antimicrobial peptide APSH‐07 on growth performance, immune response, antioxidative status and vibriosis resistance of abalone Haliotis discus hannai (initial body weight: 2.06 ± 0.01 g; initial shell length: 25.42 ± 0.18 mm). Four artificial diets were designed with 0 (artificial diet control), 7.5, 15.0 and 22.5 mg/kg of APSH‐07, respectively. The brown alga Laminaria japonica was used as the live food control. Results showed that the specific growth rates of abalone in the groups with 7.5 and 15.0 mg/kg dietary APSH‐07 were significantly higher than those in the controls (p < .05). The total haemocyte counts and respiratory burst activity in haemolymph of abalone in the group with 7.5 mg/kg of dietary APSH‐07 were significantly higher than those in the groups with 0 and 22.5 mg/kg of dietary APSH‐07 (p < .05). The gene expression levels of Mn‐superoxide dismutase and thioredoxin peroxidase 2, and the activities of glutathione peroxidase in the group with 7.5 mg/kg of dietary APSH‐07 were significantly higher than those in the other groups (p < .05). Cumulative mortality of abalone after the challenge test was significantly decreased in the group with 7.5 mg/kg of dietary APSH‐07 supplementation. Supplementation of 22.5 mg/kg dietary APSH‐07 significantly increased the cumulative mortality. In conclusion, 7.5 mg/kg of dietary APSH‐07 supplementation had the better growth performance, higher antioxidation, immune and disease resistance capacity of abalone. Excessive supplementation of dietary antimicrobial peptide APSH‐07 (22.5 mg/kg) had significantly negative effects. Further studies are needed to determine the optimal level of dietary APSH‐07 supplementation for abalone.     

“东优1号”杂色鲍及其亲本群体的形态特征和养殖性能比较

以杂交种东优1号杂色鲍及其亲本群体为研究对象,对三者的外形特征和养殖性能进行了比较。结果表明,在壳形和密度相关的参数中,壳宽/壳长指标差异最为显著,日本群体的壳宽/壳长指标显著地大于台湾群体(P<0.05),而东优1号的值则介于双亲群体之间。采用海区延绳式吊养和陆地工厂化养殖两种养成模式,分别在福建、广东和海南对东优1号杂色鲍及其亲本群体进行为期一年的养殖对比试验。结果表明,杂色鲍台湾群体受养成期暴发性死亡症的严重影响,存活率极低;日本群体虽然具有较好的抗病能力,但生长速度却显著慢于东优1号和台湾群体;东优1号杂色鲍的生长速度和存活率在3个实验点都表现出较为显著的优势。研究结果表明东优1号杂色鲍是适合在亚热带和热带地区进行养殖的优良鲍新品种。     

Growth performance of weaning red abalone (Haliotis rufescens) fed with Macrocystis pyrifera plantlets and Porphyra columbina compared with a formulated diet

A feeding experiment was carried out to evaluate two natural diets versus a formulated feed on the performance of weaning red abalone Haliotis rufescens . Four treatment diets were then investigated: a formulated diet; plantlets from culture Macrocystis pyrifera, Porphyra columbina from natural beds; and a mixed diet consisting of a blend of fresh P. columbina together with the formulated diet. This study was performed in a shallow aquaculture system with a horizontal water flow. After 90 days, significant differences were observed between treatments. The highest growth was obtained with Porphyra (3.3 mm month⁻¹), followed by the mixed diet (2.6 mm month⁻¹), then Macrocystis (2.1 mm month⁻¹) and lastly the formulated diet (1.4 mm month⁻¹). Moreover, after the diets were tested for stability and remnant nutrients after a 12-h water immersion, a positive trend appeared to be related to the protein/energy (P:E). It is concluded that fronds of P. columbina resulted in the best diet for weaning H. rufescens under horizontal water flow systems, even if apparently the water stability of the formulated diet had a negative impact on abalone performance, particularly due to a poor nutrient retention capacity. Therefore, formulated diets should be improved before being recommended for weaning red abalone.     

健康和患病稚黑鲍中微生物产胞外酶的分析比较

2005年初自福建漳浦鲍鱼场患病以及健康稚黑鲍中各分离到27和56株异养细菌,在此基础上研究了它们产胞外蛋白酶、淀粉酶、明胶酶、磷脂酶及溶血能力。结果表明,虽然来自健康鲍的菌株产胞外酶的数量明显大于来自病鲍的菌株,但来自病鲍的菌株具有强分泌胞外酶能力的比例明显大于来自于健康鲍的菌株。综合考虑每一种胞外酶的潜在致病作用,以及菌株分泌多种胞外酶的能力,最后确认10株菌为潜在的致病菌。     

The growth of disk abalone, Haliotis discus hannai at different culture densities in a pilot-scale recirculating aquaculture system with a baffled culture tank

The growth rate of disk abalone, Haliotis discus hannai, energy consumption and changes in water quality were monitored in a pilot-scale recirculating aquaculture system (RAS) for 155 days. Baffles were installed in the RAS culture tanks to enlarge the attachment area and clean out solid waste materials automatically by hydraulic force only. The experimental disk abalones, of shell length 24.5 ± 0.5 mm, were cultured at three stocking densities, 700, 1300 and 1910 individuals/m² bottom area, in triplicate. The abalones were fed with sea mustard, Undaria pinnatifida, once a week. The abalone feed conversion rates and daily growth rates ranged from 24.5 to 25.9 and 0.32 to 0.36%, respectively. Their daily shell increments and survival rates ranged from 67.7 to 78.6 μm/day and 87.6–92.2%, respectively. The growth in weight tended to decrease at a culture density of 1300 individuals/m² bottom area, while shell increments and survival rates were acceptable at this density. The total power consumption for heating was 1185.4 kW, comprising 30.2% of the total power consumption, while the average water exchange rate was only 2.9% per day. The total ammonia nitrogen stabilized below 0.07 mg/L, after conditioning of the biofilter. The NO₂⁻–N, NO₃⁻–N and total suspended solid concentrations were also maintained within acceptable ranges for the normal growth of disk abalone. The use of the RAS with these newly designed culture tanks for disk abalone culture produced 1300 individuals/m² bottom area with a water exchange rate of only 2.9% per day and used about one-tenth of the heat energy of a conventional flow-through system.