A comparison of the population genetics of Lethrinus miniatus and Lutjanus sebae from the east and west coasts of Australia: Evidence for panmixia and isolation

Lethrinus miniatus and Lutjanus sebae are important commercial and recreational species of reef fish. Within Australian waters the former species is less widespread than the latter and has a discontinuous distribution, whilst the latter is continuously distributed in tropical Australian waters. The demographic attributes of these species (e.g. long life span, low rates of natural mortality) make them vulnerable to over-exploitation. Consequently, conservative harvest strategies including no-take zones for these species have been adopted by fisheries management agencies to control exploitation. Information on the genetic stock structure of these species is important for developing specific management strategies. However, little is known about genetic stock structures within and between east and west Australian populations of these species. The current study used the mitochondrial genome hypervariable region 1 (HVR1) of the control region to examine variation between two sites from both the east and west Australian coasts for each species. HVR1 for L. sebae did not differ genetically either within or between coasts (F_st < 0.018, p > 0.15) at the sites studied, suggesting a panmictic population structure. Similarly, L. miniatus did not differ significantly between sites sampled within coast. However, the west coast HVR1 for L. miniatus east and west coast populations, were discrete (F_st of at least 0.92, p < 0.0001). The degree of genetic sub-division between east and west coast populations indicates that they should be managed as discrete stocks. Further, when considering both species, the lower genetic (both haplotype and nucleotide) diversity in three of the four sites on the west coast of Australia, indicates that this region is genetically impoverished and neutrality tests suggest that selection is responsible. Consequently, west Australian populations will be less resilient to perturbations (e.g. fishing, climate change) than east Australian populations, which have higher genetic diversity.     

Effect of the dusk photoperiod change from light to dark on the incubation period of eggs of the spotted rose snapper, Lutjanus guttatus (Steindachner)

Spotted rose snapper, Lutjanus guttatus (Steindachner), eggs were incubated under different photoperiods to examine the effect of photoperiod on incubation. The eggs from two fish were incubated under five artificial photoperiods: constant dark (D), constant light (L) from 06:00 hours and 6, 10 and 14 h of light from 06:00 hours. The eggs from seven other fish were incubated under a natural photoperiod. Different spawning times (21:00 – 01:00 hours) and different photoperiods combined to give the start of the dusk photoperiod change after 11–23 h of incubation. Constant light or applying the dusk photoperiod change after ≥20 h of incubation appeared to extend the hatching period. The mean hatching period for groups of eggs incubated in darkness or that received the dusk photoperiod change after ≤19 h of incubation (n=8 different groups) was 2 h 15±10 min, which was significantly lower (P<0.05) than the mean hatching period of 4 h±37 min for groups that did not receive the dusk photoperiod change or that received the dusk photoperiod change after ≥20 h of incubation (n=9 groups). However, despite these differences, the majority of the eggs hatched during a 2–3 h period from 17 to 20 h of incubation, and a sigmoid regression (r²=0.9) explained the relationship between percentage hatch and hours of incubation for all photoperiod groups.     

3种笛鲷的含肉率、肥满度、比肝重和肌肉营养成分的分析

对千年笛鲷Lutjanus sebae、红鳍笛鲷L.erythopterus和紫红笛鲷L.argentimaculatus及不同生长阶段千年笛鲷的含肉率、肥满度、比肝重及其肌肉生化成分进行了分析,结果表明,3种笛鲷的含肉率差异极显著,肥满度、比肝重和肌肉营养成分的差异较小,而对于不同生长阶段的千年笛鲷而言,其差异明显。肌肉粗蛋白、粗脂肪和水分含量的大小顺序均为红鳍笛鲷>紫红笛鲷>千年笛鲷。不同生长阶段的千年笛鲷,随着鱼体的生长,其含肉率增加,肥满度和比肝重降低;粗蛋白和粗脂肪含量增加,水分和灰分含量减少。     

金焰笛鲷rDNA基因转录间隔区ITS-1序列分析

以持异性引物扩增了金焰笛鲷(Lutjamts fulviflamma)的核糖体第一转录间隔区(ITS-1),扩增产物经克隆后测序,测得 ITS-1长度为566 bp。其中 A、T、G、C 4种碱基的含量分别为14.1%、16.1%、30.2%、39.6%,G C(69.8%)含量明显高于 A T 含量(30.2%)。将此引物在笛鲷属其他4种鱼类中扩增,发现该对引物有很好的通用性;比较发现在不同种中 ITS-1存在着较大的差异,适合将其应用于分子系统学和种质资源方面的研究。     

Assessing the use of a dietary probiotic/prebiotic as an enhancer of spinefoot rabbitfish Siganus rivulatus survival and growth

The use of prebiotics and probiotics as feed supplements that improve efficiency of intestinal bacteria is becoming de rigueur in animal husbandry in many regions worldwide. We tested the effects of a commercial probiotic (Biogen^®) containing allicin, high unit hydrolytic enzyme, Bacillus subtilis spores and ginseng extracts on survival, growth, carcass composition and feed cost/benefit in rabbitfish Siganus rivulatus. Fifteen net cages (100 × 100 × 40 cm; L × W × H) were stocked with 10 juvenile rabbitfish (10.3 g per fish) each and placed in a large rectangular tank and offered feed at 4% body weight daily. Cages were offered one of five isonitrogenous and isocaloric diets containing 0, 1, 2, 3 and 4 g kg⁻¹ probiotic at three replicates per treatment for 98 days. Fish in all cages were weighed at 2‐week intervals and feed regimen was adjusted accordingly. Rabbitfish offered the control diet exhibited lower growth and feed utilization than all experimental treatments. There was no effect of probiotic inclusion level on survival but growth was better at all inclusion levels than in the control. No significant differences (P > 0.05) in growth were observed among fish groups fed various levels of the probiotic. Carcass composition was not affected by dietary probiotic inclusion. Ultimately, when all variables are considered, Biogen^® inclusion to diets appears to reduce feed cost per unit growth of rabbitfish.     

氟苯尼考在红笛鲷体内的药代动力学研究

为研究氟苯尼考在红笛鲷体内的药代动力学特征,在水温(20±2)℃条件下,氟苯尼考以10 mg/kg单剂量腹注和口灌健康红笛鲷(Lutjanus sanguineus),采用HPLC-MS/MS测定组织中的药物浓度,数据用DAS3.0软件分析。结果显示,两种给药方式下红笛鲷血浆药时数据均符合一级吸收二室模型;腹注给药后血浆、肝脏、肾脏和肌肉的峰浓度(C_(max))分别为10.62μg/m L、8.36、22.57和4.76μg/g,达峰时间(T_(max))分别为1.2、1.0、1.0和6.0 h,消除半衰期(t_(1/2β))分别为29.76、17.84、17.23和19.48 h;口灌给药后血浆、肝脏、肾脏和肌肉的C_(max)分别为2.35μg/m L、1.45μg/g、4.06μg/g和1.73μg/g,T_(max)分别为2.69、1.5、1.5和4.0 h,t_(1/2β)分别为40.59、12.29、37.78和47.34 h。结果表明,腹注给药方式下氟苯尼考在红笛鲷体内的吸收快于口灌给药,在血浆和肝脏中的消除快于口灌给药,在肌肉和肾脏中的消除则慢于口灌给药。研究结果为氟苯尼考在临床上的合理应用提供了科学依据。     

Dietary protein requirement of juvenile marbled spinefoot rabbitfish Siganus rivulatus

Rabbitfish are an Indo‐Pacific herbivorous marine fish that have good market demand and are suitable for aquaculture. The present work was performed to determine dietary protein inclusion necessary for optimal growth of juvenile rabbitfish Siganus rivulatus. Six diets with increasing levels of protein (10, 20, 30, 40, 50 and 60 g crude protein 100 g^?1 feed) and similar levels of gross energy (20 MJ kg^?1) were prepared and offered to S. rivulatus juveniles maintained in triplicate cages placed in two large water tanks for 49 days. Growth progressively improved with dietary protein for fish offered diets from 10% to 40% protein inclusion. Diets with greater protein levels did not improve fish growth beyond that observed in the 40% group. Daily feed intake, apparent protein utilization and feed conversion ratio decreased as dietary protein increased. Protein efficiency (PE) was greatest (1.47) in fish offered the 10% protein diet and least in fish offered the 60% protein diet (0.80). No differences in PE were observed among all other treatments (20–50%). Results of the present work suggest that minimum dietary requirement for suitable growth of S. rivulatus juveniles is 40% protein when digestible energy of the diet is 16–18 MJ kg^?1.     

湛江港区底泥悬浮物对2种海洋动物的致死效应研究

为评价湛江沿海涉海工程建设过程中引起的悬浮物质对附近海区海洋动物的影响,研究了底泥液相及不同浓度底泥悬浮物对川纹笛鲷和尖吻鲈的致死效应。试验结果表明,在8d的试验时间里,底泥水相对川纹笛鲷和尖吻鲈均无致死效应。底泥悬浮物浓度≤160mg/L时,川纹笛鲷和尖吻鲈的死亡率均处于较低水平。底泥悬浮物浓度≥2560 mg/L时,川纹笛鲷死亡率达75%,尖吻鲈死亡率达70%。通过概率单位法计算得出川纹笛鲷的8d半致死浓度为716.14 mg/L,尖吻鲈的8d半致死浓度为1105.096 mg/L。     

Substitution of fish meal by soybean meal in diets for juvenile marbled spinefoot,Siganus rivulatus

The present work was performed to assess whether soybean meal (SBM) could replace fish meal (FM) as a source of dietary protein in diets of the marine herbivore Siganus rivulatus. Five iso-nitrogenous (40% protein) and iso-energetic (14 MJ/Kg) diets were prepared with SBM replacing fish meal at 0%, 25%, 50%, 75%, and 100% dietary protein. A 60-day feeding trial was conducted with 240 juvenile S. rivulatus (initial body mass 1.74 ± 0.03 g). Survival, growth, feed, and protein efficiency and hematological parameters were assessed. Growth correlated negatively with increase in dietary SBM. All production parameters measured were negatively affected at all levels of SBM inclusion. There were no effects on total or differential blood counts, hemoglobin, or plasma protein, but hematocrit values were negatively correlated with SBM addition. Results suggest that total replacement of FM by SBM without adding other supplements is not recommended, even for an herbivorous marine fish such as S. rivulatus.     

恩诺沙星对红笛鲷血清中碱性磷酸酶活力、抗体IgM含量、溶菌酶含量及其抗菌能力的影响

以间隔200mg／kg的恩诺沙星设置8个浓度梯度腹腔注射红笛鲷进行急性毒性实验,测得其安全浓度为67．56mg／kg,参考安全浓度及日常生产给药量取0、20、40、80mg／kg鱼体重恩诺沙星,以腹腔注射及拌料投喂两种不同给药方式,研究恩诺沙星在该浓度范围内对红笛鲷血清中一些免疫指标及其感染细菌后死亡率的影响。实验结果表明恩诺沙星在40m非g浓度组中提高AKP活力、IgM含量、溶菌酶含量的同时可提高红笛鲷抵抗外界细菌感染的能力（P〈0．05）。当用药浓度不足（20mg/kg组）或浓度过高（80mg／kg组）,虽然对AKP活力和IgM含量也有影响,但在投喂组中,红笛鲷体内的IgM含量受抑制显著,经腹腔注射2．3×10^7 CFU／mL溶藻弧菌 （ Vibrio alginolyticus ）攻毒后,注射组中相对生理盐水组的死亡率55％;20、40、80mg／kg浓度组红笛鲷的死亡率分别为45％、30％、50％;投喂组中,0、20、40、80mg,kg浓度组红笛鲷的死亡率分别为55％、40％、30％、60％;40mg／kg浓度组中抗菌能力增强;20、80mg／kg浓度组中红笛鲷抗菌能力不受影响或有负面影响。