Effect of dietary phosphorus levels on growth and body composition of crucian carp,Carassius auratus under indoor and outdoor experiments

Indoor and outdoor experiments were carried out simultaneously to evaluate the effects of dietary phosphorus levels on growth performance and body composition of crucian carp. Monocalcium was used to formulate extruded feed containing available phosphorus (AP) of 1.5 (D1), 4.7 (D2), 6.3 (D3) and 9.0 (D4) g kg^?1. Twelve 500‐L recirculating tanks were assigned to four triplicate groups with each tank stocked with 15 juveniles (39.88 ± 0.14 g) for indoor experiment. Twelve polyethylene enclosures were assigned to four groups with each one stocked with 120 juveniles (44.08 ± 1.36 g). After 8 weeks of feeding, survival ranged from 96% to 100%. Weight gain, special growth rate, protein efficiency ratio and feed conversion rate did not show significant differences among dietary treatments in both experiments. Fish cultured in the enclosures grew better, although D1 and D2 treatments did not reach significant level. Crude protein and phosphorus content of the fish were not significantly affected by dietary phosphorus level. Moisture, crude lipid, crude ash and vertebrae phosphorus were significantly affected by different phosphorus levels. Based on vertebrae phosphorus, crucian carp cultured in the tanks and in the enclosures showed phosphorus deficiency under 4.7 g kg^?1 and 6.3 g kg^?1 AP, respectively.     

文蛤增养殖区主要环境因子变化规律研究

2004年和2005年分别对江苏省沿海滩涂4个具有代表性的文蛤重点增养殖区的环境因子进行了连续调查、监测和研究,主要分析测试了以下3个对文蛤生存影响较为重要的环境因子:底泥中的硫化物(S2-)、底泥渗水中的总氨氮(NH4-N)和底泥渗水中的化学需氧量(COD)。结果表明:S2-季节性变化明显,地点上随监测站位不同有显著差异;NH4-N夏季较高,其它时段基本无变化,均值远远高于上覆水体;COD含量除受气温影响外,还显著受到人类生产生活(如排污等)的影响。另外,2005年较2004年部分监测站位养殖环境有恶化趋势。     

Effects of different dietary copper sources on the growth and intestinal microbial communities of Pacific white shrimp (Litopenaeus vannamei)

An 8‐week feeding trial was conducted to evaluate the effects of dietary copper sources on growth performance and intestinal microbial communities of juvenile Pacific white shrimp (Litopenaeus vannamei). Four isonitrogenous (420 g/kg crude protein) and isolipidic (70 g/kg crude lipid) experimental diets were formulated to contain different copper sources, Diet NSC (no‐supplemented copper), Diet CS (copper sulphate), Diet Availa (copper amino acid complex from Availa^®Cu100) and Diet M (1:1, copper sulphate + copper amino acid complex). A total of 360 Pacific white shrimp juveniles (initial weight: 1.86 ± 0.03 g) were randomly allocated into four groups, with three replicates per group and 30 shrimps each replicate. An Illumina‐based sequencing method was used to analyse the intestinal bacterial composition of shrimp juveniles. The results revealed that shrimps fed Diet M had significantly higher percent weight gain (PWG) than that fed Diet NSC and Diet CS, while there were no significant differences between Diet M and Diet Availa. Survival was not affected by the dietary copper sources. Proteobacteria and Bacteroidetes were dominant in the intestines of Pacific white shrimp. Shrimps fed Diet M and Diet Availa had higher bacterial richness and diversity than those fed Diet NSC and Diet CS with no significant differences among all treatments. Furthermore, Diet M and Diet Availa which contained copper amino acid complex reduced the relative abundance of Vibrionaceae in shrimp intestinal tract. This study indicated that dietary copper sources could affect the intestinal microbial communities and diets supplemented with Availa^®Cu100 could have a positive impact on the growth performance and decrease the potential risk of disease in Pacific white shrimp.     

Competition of infectious hypodermal and haematopoietic necrosis virus (IHHNV) with white spot syndrome virus (WSSV) for binding to shrimp cellular membrane

Infectious hypodermal and haematopoietic necrosis virus (IHHNV) and white spot syndrome virus (WSSV) are two widespread shrimp viruses. The interference of IHHNV on WSSV was the first reported case of viral interference that involved crustacean viruses and has been subsequently confirmed. However, the mechanisms underlying the induction of WSSV resistance through IHHNV infection are practically unknown. In this study, the interference mechanisms between IHHNV and WSSV were studied using a competitive ELISA. The binding of WSSV and IHHNV to cellular membrane of Litopenaeus vannamei was examined. The results suggested that there existed a mutual competition between IHHNV and WSSV for binding to receptors present on cellular membrane of L. vannamei and that the inhibitory effects of WSSV towards IHHNV were more distinct than those of IHHNV towards WSSV.     

养殖密度对宝石鲈生长性能和血液生化指标的影响

试验对循环水养殖系统中不同养殖密度宝石鲈(50,100,150,220尾/m3)的生长性能及血液生化指标进行比较.结果表明,150尾/m3组宝石鲈的生长较有优势,其特定生长率(1.61%/d)和存活率(89%)均较高,饲料系数较低(1.70);密度对血液中的谷草转氨酶、谷丙转氨酶和胆红素的影响显著(P＜0.05),随养殖密度增加其浓度呈上升趋势,均在220尾/m3密度组上升最多;密度对血清无机离子(钾、钠、氯、镁、磷)也有影响.综合认为循环水养殖条件下,150尾/m3养殖密度组宝石鲈生长效果较具优势.     

三种鲤对暴发性鱼病抗病力的差异

本文报道三种鲤对嗜水气单胞菌引起暴发性鱼病的抗病力试验结果。当菌液浓度为６．０×１０￣８ＣＦＵ／ｍｌ，采用１０￣０、１０￣（－１）、１０￣（－２）、１０￣（－３）四个稀释度、０．３ｍｌ／尾注射剂量时，建鲤、野鲤和镜鲤的半数致死量（ＬＤ＿（５０））分别为１０￣（－１．３７５）、１０￣（－０．９７６）、１０￣（－０．５６２）。这三种鲤的半数致死量差异显著（Ｆ＞Ｆ＿（０．０５））。从四个方面研究了抗病机理：白细胞吞噬功能和补体替代途径（Ｃ＿３旁路）杀菌能力，镜鲤较强于野鲤和建鲤，但无显著差异（Ｆ＜Ｆ０．０５）；红细胞Ｃ＿（３ｂ）受体花环率和补体总量（单位／ｍｌ），是建鲤＞野鲤＞镜鲤，差异极显著（Ｆ＞Ｆ０．０１）。本研究结果还表明建鲤的红细胞Ｃ＿（３ｂ）受体花环率和补体总量稍高，但对暴发性鱼病病原（嗜水气单胞菌）较易感染。以上结果证明，不同品系鲤鱼对暴发性鱼病有种内特异性。     

九孔鲍北方青苗及生长的探讨

探讨了九孔鲍(Haliotisdiversicolorsuertexta)在北方自然繁殖季节育苗的条件、发育时间和生长速度。2004年8月1日,用紫外线照射海水诱导产卵和人工授精的九孔鲍受精卵,经过60天培育,获6～12mm的幼鲍50万只。     

不同氮磷比对福建沿海米氏凯伦藻生长的影响

本文在不同氮磷比(N∶P=4∶1、8∶1、16∶1、32∶1、80∶1)培养条件下,对福建沿海赤潮海域分离的米氏凯伦藻(Karenia mikimotoi)进行培养,研究其生长特性。实验结果表明:不同的氮磷比对米氏凯伦藻的生长有明显的影响。过高或过低的氮磷比均不适合米氏凯伦藻的生长,该藻在N∶P=32∶1条件下比生长率最快,为0.33 d-1。米氏凯伦藻对氮的需求高于磷,在适当的磷限制环境中能够维持更长的生长周期。引发赤潮的主要原因并不是由于米氏凯伦藻赤潮暴发海域的低氮磷比,而是赤潮暴发过程中,米氏凯伦藻对营养盐的大量消耗,尤其是对氮的消耗。     

日粮水平和饵料种类对真鲷能量收支的影响

以玉筋鱼为铒料生物,采用室内流水模拟实验法研究了摄食水平和饵料种类对真鲷能量收支各组分和能量收支分配模式的影响。结果表明,真鲷的生长量、总代谢量、排泄量及生态转换效率均随日粮水平升高呈减速增长趋势,二者之间的定量关系均可用对数曲线加以定量描述;不同生物饵料能造成真鲷摄食、生长、排泄和总代谢水平的显著差异,但却不能改变以比能值为单位的生态转换效率。依据各收支过程的量化结果,可得到真鲷的能量分配模式。     

浙南沿海羊栖菜繁殖生物学的初步研究

本文研究了羊栖菜的有性生殖和营养繁殖。前者包括生殖托的发生、精卵的排放及合子的发育与环境因子的关系。后者主要为定株观察假根再生芽的发生。本研究为羊栖菜的人工育苗和资源保护提供了科学依据。