Effects of stocking density and algal concentration on the survival,growth and metamorphosis of Bobu Ivory shell,Babylonia formosae habei (Neogastropoda: Buccinidae) larvae

Independent and combined effects of stocking density and algal concentration on the survival, growth and metamorphosis of the Bobu Ivory shell Babylonia formosae habei larvae were assessed using a 5 × 5 factorial design with densities of 0.25, 0.5, 0.75, 1.00 and 1.50 larvae mL⁻¹ and algal concentrations of 5, 10, 15, 20 and 25 × 10⁴ cells mL⁻¹ in the laboratory. Larval growth, survival and metamorphosis were significantly affected by both the independent effects of stocking density and algal concentration and by their interaction. The highest per cent survival (72.5%) and metamorphosis (49.5%), fastest growth (41.57 μm day⁻¹) and shortest time to initial metamorphosis (10 days) all occurred at the lowest stocking density and the highest algal concentration. Both crowding and food limitation had independently negative impacts on the survival, growth and metamorphosis of larvae, and these negative impacts were further strengthened by the interaction of a higher stocking density and a lower algal concentration. Moreover, the results suggest that stocking density and algal concentration obviously played different roles in determining larval survival and growth. To maximize survival and growth, B. formosae habei larvae should be reared at a lower stoking density of 0.25 larvae mL⁻¹ and fed a higher algal concentration of 25 × 10⁴ cells mL⁻¹ in large-scale hatchery seed culture.     

台湾东风螺和方斑东风螺蛋白质氨基酸组成和营养价值比较研究

测定了野生台湾东风螺、方斑东风螺及养殖东风螺肌肉干物质的氨基酸含量。结果显示东风螺肌肉蛋白质含有较丰富的必需氨基酸。干物质中水解氨基酸总量从61·14%到64·68%,总必需氨基酸含量从27·73%到29·41%,占氨基酸总量的45·35%到47·55%;呈味氨基酸含量从23·68%到26·50%,平均值为24·77%,占氨基酸总量的42·56%。台湾东风螺和方斑东风螺的第一限制氨基酸均为苏氨酸。野生台湾东风螺氨基酸总量、必需氨基酸含量、总鲜味氨基酸及氨基酸分(64·68%,29·41%,26·50%和49·56)均高于方斑东风螺(60·14%,26·73%,24·87%和41·46),认为台湾东风螺比方斑东风螺更为优良和美味,应该加大开发其利用价值。     

不同蛋白水平饲料对台湾东风螺生长性能和体组成的影响

以优质鱼粉、豆粕等原料制成蛋白质含量不同的6组饲料(粗蛋白含量分别为48.16%、45.64%、40.67%、35.68%、30.80%、25.96%),喂养台湾东风螺47 d,以投喂鲜杂鱼组作为对照,分别于15、27、37、47 d测定螺高、螺宽、螺体重等生长指标,计算不同处理组在不同时间段(27、37、47 d)的饲料系数和蛋白质效率,试验结束后测定东风螺螺肉的体组成和氨基酸含量,研究结果表明:投喂颗粒饲料比投喂鲜杂鱼的饲料系数显著高;而当颗粒饲料中蛋白质含量变化(25%~48%)时,对东风螺生长性能并无显著影响。但随着饲料蛋白含量的增加,东风螺对饲料的利用率在一定程度上有所提高。当饲料中粗蛋白含量低于25%时,47 d时其饲料系数2.3,显著高于其他饲料组;蛋白质效率1.74显著低于蛋白含量48.16%饲料组。从东风螺生长性能和饲料利用分析,颗粒饲料中蛋白质含量不应低于25%。所有组东风螺螺肉的粗蛋白、脂肪,总氨基酸组成均无显著差异,但是一些中性氨基酸(如亮氨酸、异亮氨酸和丙氨酸)和精氨酸随着饲料蛋白含量的降低而呈现出降低趋势,部分组产生了显著差异。投喂颗粒饲料的东方螺生长不如投喂鲜杂鱼组。     

Feeding rate responses of Babylonia formosae habei (Prosobranchia: Buccinidae) larvae on cultured algae

Babylonia formosae habei is a commercially important marine gastropod species. Food particles ingested by the planktotrophic larvae of B. formosae habei can be critical in maximizing the larval growth and survival of this species. In this study, feeding rate responses of B. formosae habei larvae on cultured algae were observed using a Coulter multisizer. Variations were recorded based on the changes of different factors of influence, including varied larval stoking density, varied types of algae, varied algae concentrations and selective feeding on mixed algae cells of different types. Results of this study reveal some facts on the feeding of B. formosae habei larvae: larval stoking density has negative effect on their feeding rates; larva has a higher feeding rate on big‐sized algae than small‐sized algae; larva has a higher feeding rate on diatom than green algae and flagellate; feeding rate of larvae increased when fed mixed algae cells. Optimal algal concentration of the cultured algae Chlorella sp., Chaetoceros muelleri, Isochrysis zhanjiangensis and Dunaliella tertiolecta was suggested at 20 × 10⁴, 5 × 10⁴, 20 × 10⁴ and 10 × 10⁴ cells mL^?1 respectively. Results of the preset study can be important in understanding feeding ecology of B. formosae habei larvae, and applicable for the aquaculture of this species.     

Effects of food availability on feeding and growth of cultivated juvenile Babylonia formosae habei (Altena & Gittenberger 1981)

Juveniles of the scavenging gastropod Babylonia formosae habei ( Altena & Gittenberger 1981 ) were kept at different ration levels in the laboratory for 30 days. Feeding behaviour and growth performance of the juveniles in relation to food availability were studied. Babylonia formosae habei juveniles were exposed to one of the four ration levels with food provided once either every 1, 2, 5 or 10 days. Higher food consumption, longer time spent on feeding and higher percentage of feeding individuals were obtained in individuals maintained at lower ration levels. Similar growth performances were observed in individuals fed once every day or every two days. A sustained production of shell was obtained in the juveniles maintained at low ration levels. At the end of the experiment, lower protein and lipid content as well as lower energy content were measured in the somatic tissue of juveniles maintained at lower ration levels. During the 30‐day experiment, food availability is not a crucial factor on survival of juvenile B. formosae habei due to its physiological and behavioural adaptations developed in association with starvation.     

饥饿对波部东风螺幼虫存活_生长及变态的影响

对波部东风螺幼虫进行不同时间的初次投饵实验，测定了饥饿对波部东风螺幼虫存活、生长及变态的影响。幼虫自身存在一个耐受饥饿不可逆点，实验测得约为１０５ｈ。饥饿条件下，卵黄作为幼虫早期的内源性营养，对维持幼虫的生存和生长都起着相当重要的作用。３６ｈ的短时间饥饿并不影响幼虫的生长，但随着饥饿时间的延长，幼虫的存活率、变态率显著地降低，生长速度明显变慢；幼虫自发变态时间随着饥饿时间的延长而延长，二者呈线性关     

2种东风螺繁殖及苗种生长发育的比较

对方斑东风螺Babylonia areolata(Link)和台湾东风螺B·formosae(Sowerby)进行人工繁育试验,结果表明:在水温23·6±1·1℃和充气条件下,方斑东风螺的孵化时间为8d,台湾东风螺的孵化时间为7d;刚孵出幼体壳长方斑东风螺为482·7±10·6μm,台湾东风螺为398·2±10·3μm。在水温25·2±0·9℃、培育密度为0·1~0·2ind·mL-1左右时,方斑东风螺幼体壳长增长速度可达33·6μm·d-1,约在第18天开始进入附着变态,变态时壳高为1323·9±118·6μm;台湾东风螺幼体壳长增长速度为25·3μm·d-1,约在第16天开始进入附着变态,变态时壳高为955·5±74·4μm。在水温26·5±0·7℃、培育密度为2100ind·m-2左右时,方斑东风螺和台湾东风螺的稚贝壳高增长速度分别为0·21和0·20mm·d-1。