Occurrence of the Enigmatic, Unicellular Psorospermium Organism in Several Cultured, Sympatric Populations of the Freshwater Crayfishes Procambarus clarkii and Procambarus zonangulus

The parasitic Psorospermium organism was studied in cultured sympatric populations of mature Procambarus clarkii and Procambarus zonangulus during four consecutive annual crayfish seasons from 1991–1992 through 1994–1995. Most P. clarkii were infected while fewer than half of the P. zonangulus were infected throughout the study period. The numbers of Psorospermium were four to eight times greater in P. clarkii and showed annual changes not seen in P. zonangulus . Both crayfishes demonstrate 1yr life cycles in Louisiana and this seemed to explain the variations seen in Psorospermium dynamics in the two hosts. In general, there was no consistent association between crayfish size and the number of parasites found in them for either crayfish species. There was some indication of an association between the presence of infection and the number of parasites found in P. zonangulus .     

Procambarus clarkii Girard as a vector for the crayfish plague fungus, Aphanomyces astaci Schikora

Abstract. Procambarus clarkii Girard, a native freshwater crayfish species of Lousiana, USA, was found to harbour the crayfish plague fungus, Aphanomyces astaci Schikora, in its cuticle as a benign infection. Under certain conditions, P. clarkii dies as a result of this parasite, and the A. astaci infection then becomes acute and can be transmitted to Astacus astacus (L.).
Therefore, it is now shown that at least three different species of North American crayfish ( Pacifastacus leniusculus Dana, Orconectes limosus Raff, and Procambarus clarkii Girard) can carry the crayfish plague fungus, A. astaci , can transfer the disease to other crayfish species, and under certain circumstances can die of its own infection.     

Occurrence of Psorospermium sp. in several North American crayfish species, with comparative notes on Psorospermium haeckeli in the European crayfish, Astacus astacus

Psorospermium haeckeli is a thick-walled, unicellular organism widely reported in European astacid crayfish. Its taxonomic status and life cycle have not been elucidated. It is often referred to as a “parasite”, but conclusive evidence has yet to be found. Recent examination of two North American crayfish species, Procambarus clarkii and Procambarus zonangulus, confirmed its presence in the south-central USA (Louisiana) with morphologies that differ from that of P. haeckeli. This form had been previously reported from Orconectes virilis in southern Canada. We report here the presence of this North American form of Psorospermium in additional North American crayfish including Orconectes immunis and Orconectes rusticus from the northern USA (Minnesota and Wisconsin), Procambarus alleni and Procambarus fallax from the southern USA (Florida), and Pacifastacus leniusculus from the western USA. We also confirm this Psorospermium in O. rusticus from eastern Canada (Ontario). It was not, however, confirmed in several additional southern crayfish species including Cambarus diogenes, Cambarellus puer, Fallicambarus fodiens, and Orconectes palmeri. We describe the morphological forms of this Psorospermium and conclude that it is present in many crayfish species in North America.     

盐度与体重对克氏原螯虾代谢的影响

在水温为20.0±0.5℃条件下,研究了不同盐度(0、3.0、6.0、9.0、12.0)和不同体重(平均体重为7~8 g、19~20 g两种规格)对克氏原螯虾的耗氧率、CO2排出率以及NH3-N排泄率的影响。结果表明,低盐度条件下(0~6.0),两种规格克氏原螯虾的耗氧率、CO2排出率和NH3-N排泄率均随着盐度的升高而显著上升(P<0.05),盐度为6的条件下代谢水平达最高值,此后随着盐度的升高耗氧率、CO2排出率和NH3-N排泄率显著下降(P<0.05);相同盐度下,小规格(平均体重为7~8 g)克氏原螯虾的耗氧率、CO2和NH3-N排泄率显著高于大规格虾(平均体重为19~20 g)。相同规格的克氏原螯虾在不同盐度条件下呼吸商、氧氮比均无显著差异(P>0.05),但是大规格的克氏原螯虾呼吸商和氧氮比显著大于小规格的虾(P<0.05),前者的代谢率极显著低于后者(P<0.01)。     

养殖密度对克氏原螯虾生长及消化酶、免疫酶活性的影响

水温(25±1)℃时,将体质量(3.11±0.10)g的克氏原螯虾幼虾饲养在120 cm×60 cm×20 cm的水族箱中,密度分别为14尾/m2(低密度组)、28尾/m2(中密度组)和42尾/m2(高密度组),研究室内养殖不同密度对生长、摄食、消化酶活性及非特异性免疫的影响.8周的养殖结果显示,克氏原螯虾的存活率随养...     

克氏原螯虾对3种不同生长型沉水植物清水态系统的影响

鉴于克氏原螯虾（Procambarus clarkii）是目前全球入侵最广、对淡水生态系统最具破坏性的物种之一,探究其对沉水植物清水态系统的影响,有助于防范克氏原螯虾入侵给浅水湖泊带来的生态风险。通过受控实验,研究了克氏原螯虾对直立型沉水植物轮叶黑藻（Hydrilla verticillata）、冠层型沉水植物穗花狐尾藻（Myriophyllum spicatum）和莲座型沉水植物密刺苦草（Vallisneria denseserrulata）的影响以及不同植物培养系统对理化因子的响应变化。结果显示,直立型轮叶黑藻相对生物减少量（60.5%）大于冠层型穗花狐尾藻（45.7%）和莲座型密刺苦草（39.0%）;克氏原螯虾进入后导致3种生长型沉水植物清水态系统的总悬浮物浓度、叶绿素a和营养盐均极显著增高（P<0.01）。研究表明,水生态系统中的克氏原螯虾会直接降低沉水植物生物量,并扰动底泥增加水体的悬浮物、叶绿素a和营养盐浓度,导致水体由清水态向浊水态转变,也会通过直接牧食或扰动破坏,降低沉水植物生物量,最终影响草型清水态系统的稳定性。     

Effects of Pond Renovation on White River Crayfish,Procambarus acutus acutus Production

Abstract

The effects of renovation on the production of white river crayfish, Procambarus acutus acutus were evaluated in ten 0.1-ha earthen ponds. The bottoms and levees of five ponds were reshaped with heavy equipment prior to planting sorghum-Sudan grass forage during the de-watered phase of the culture cycle. Five non-renovated ponds served as a control. The mean total length (TL) of the crayfish harvested from renovated ponds was significantly larger than those crayfish harvested from non-renovated ponds. The renovated pond harvest contained an estimated 43.2% carryover crayfish (>95 mm TL) in comparison to 7.6% in the harvest from non-renovated ponds. By weight, carryover crayfish constituted an estimated 69.3% of the harvest from renovated ponds, compared to 21.0% from non-renovated ponds. No difference was observed in the harvest between treatments; however, the low proportion of young-of-the-year crayfish in the renovated pond harvest may adversely impact future production.     

Estimation of the Dietary Lipid Requirement Level of the White Crayfish Procambarus acutus acutus

Six isonitrogenous and isoenergetic diets containing graded levels of lipid (menhaden fish oil) were fed to juvenile white crayfish ( Procambarus acutus acutus ) over a 10 week period. A significant depression in weight gain was observed in crayfish fed diets containing 9% or more lipid. There were no significant differences in growth of crayfish fed diets containing 0 to 6% lipid. Whole-body percentages of lipid and dry matter decreased, and protein increased in crayfish fed high-lipid diets. Dietary lipid did not appear to influence survival or molting frequency. Whole-body lipids generally reflected dietary fatty acid composition.     

注射白斑综合征病毒对克氏原螯虾酚氧化酶活力的影响

将白斑综合征病毒(white spot syndrome virus,WSSV)、嗜水气单胞菌(Aeromonas hydrophila,Ah)、大肠杆菌(Escherichia coli)(DH5α)用注射法接种克氏原螯虾(Procambarus clarkii),在0~72 h之间定时检测克氏原螯虾血细胞和肝胰脏中酚氧化酶(Phenoloxidase,PO)活力变化。结果显示:(1)0.1 mg/m L和1 mg/m L胰蛋白酶处理样品后,样品间差异不显著。(2)加胰蛋白酶处理与未加胰蛋白酶相比,供试克氏原螯虾PO活力均升高。(3)未加胰蛋白酶与加胰蛋白酶表现出相似的特征,WSSV和Ah注射组与对照组相比均表现为,12~48 h PO活力显著高于对照组,并且在48 h达到最大值,72 h时基本恢复正常;注射DH5α组与对照组相比没有显著性变化。可见感染WSSV后,克氏原螯虾体内酚氧化酶活力发生了变化,由此推测,PO参与了螯虾体内抵御病毒的免疫反应。     

不同地区克氏原螯虾群体的形态差异分析

运用3种多元统计方法,对江苏、安徽、山东和湖北4个不同地区克氏原螯虾（Procambarus clarkii）野生群体的13个形态比例参数进行比较研究。聚类分析结果显示,山东和江苏2个克氏原螯虾群体之间的形态最为接近,而与湖北和安徽群体间趋异程度逐渐增大。主成分分析中,雌性群体贡献率分别是主成分1为46.104%、主成...     

不同地区克氏原螯虾群体的形态多样性分析

运用3种多元统计方法,对江苏、安徽、山东和湖北4个不同地区克氏原螯虾(Procambarus clarkii)野生群体的13个形态比例参数进行比较研究。聚类分析结果显示,山东和江苏2个克氏原螯虾群体之间的形态最为接近,而与湖北和安徽群体间趋异程度逐渐增大。主成分分析中,雌性群体贡献率分别是主成分1为46.104%、主成分2为25.375%、主成分3为10.830%,累积贡献率为82.309%;而雄性群体贡献率分别是主成分1为50.611%、主成分2为26.365%、主成分3为8.623%,累积贡献率为85.599%。判别分析中,雌体准确率P1为70.6%～100.0%,P2为52.9%～100.0%,综合判别率为87.6%;雄体准确率P1为66.7%～100.0%,P2为66.7%～100.0%,综合判别率为92.1%。研究结果表明,不同地区克氏原螯虾群体间已经产生了一定程度的形态差异,且主要表现在头胸甲部和腹部的性状上,但这些差异尚未达到亚种水平,需多项参数综合分析才能进行不同群体间的辨别。     

Acute Toxicity of 5% Non-Synergized Emulsifiable Rotenone to White River Crayfish Procambarus acutus acutus and White Perch Morone americana

Annual drawdown of crayfish culture ponds to plant forage crops also serves to eradicate most predaceous finfish. Without annual drawdown predaceous fish populations may reach numbers that can significantly reduce the crayfish crop. Frequent drawdown may not be feasible or desirable in some management schemes. Evidence in the literature suggests that differential toxicity of rotenone would allow removal of fish without harming crayfish in the same pond. In the current study, laboratory and in situ acute toxicity bioassays (96 h) were conducted with 5% non-synergized emulsifiable rotenone to define the maximum non-lethal concentration (LC₁₀₀) for white river crayfish Procambarus acutus acutus and the minimum lethal concentration (LC₁₀₀) for white perch Morone americana . Six concentration levels of rotenone formulation were tested in each of six toxicity trials with crayfish using dechlorinated tap water at 21–25 C. LC₀ (compensated for control mortality) was determined to be 3.0 mg/L. Significant crayfish mortality began at 4.0 mg/L. Acute toxicity to white perch was anticipated to be within recommended concentration levels on product label for similar fish, and was corroborated by laboratory bioassay (LC₁₀₀ of 0.15 mg/L). Both species were then tested together in laboratory aquaria utilizing pond water at room temperature. Concentration levels of 0.05–2.5 mg/L killed all white perch with no crayfish mortality. In the final phase of the study a 1.0 mg/L concentration of rotenone was applied to a pond containing both species held in cages. All white perch were dead within 24 h; no crayfish mortality was observed for the 96-h duration of the trial. It may therefore be possible to use this rotenone formulation to control white perch and other finfish in active crayfish culture ponds.     

亲缘关系对克氏原螯虾仔虾种内斗争的影响

将源于1、2、3、4尾雌虾的克氏原螯虾仔虾以4种方式混养,每个混养群体共有仔虾24尾,设3个重复。结果表明:亲缘关系对幼年螯虾种内斗争影响显著。随着仔虾来源的增多即亲缘关系复杂性的提高,螯虾的存活率总体呈下降趋势,而残虾率、体长变异系数、体长增长率总体上显著上升。     

Effects of Harvest Period on the Production of White River Crayfish,Procambarus acutus acutus

Abstract

Crayfish harvest was initiated at a cool water temperature (15°C) and warm water temperature (20°C) from culture ponds (0.1 ha) with a resident population of white river crayfish, Procambarus acutus acutus.Crayfish were harvested for 24 days for a total of 1,977 trap-days/ha (March 9-May 12, 2000 from the cool-harvest treatment and May 5-June 15, 2000 from the warm-harvest treatment). The mean total length (TL) and production of harvested white river crayfish (WRC) was similar between treatments. The population structures of WRC from the cool and warm periods of harvest were substantially different; large WRC (≤100 mm TL) from the cool-harvest period were 3.1 times more abundant than large WRC during the warm-harvest period. A similar number of small WRC were harvested from the two treatments; however, those small WRC harvested during the warm period was significantly longer than the small WRC during the cool-harvest period. The estimated large WRC biomass contribution to the total harvest from the cool-harvest period was 37% in comparison to 15% during the warm-harvest period. The estimated dollar value of the production during the cool-harvest period was 40% more than that from the warm-harvest period.     

饲料中蛋白质水平对克氏原螯虾生长性能及肌肉品质的影响

以初始平均体质量为(3.69±0.05)g的克氏原螯虾幼虾为研究对象,配制蛋白质水平分别为27.72％、30.09％、33.05％、35.31％和37.57％的5种等能、等脂的配合饲料,进行为期47 d的饲养试验,探索饲料中不同蛋白质水平对克氏原螯虾生长性能、肌肉质构特性、常规营养成分及氨基酸组成和含量的影响.结果 表...     

溴氰菊酯对克氏原螯虾的氧化胁迫效应

为了解溴氰菊酯对克氏原螯虾的毒性及致毒机理,采用24h换水式生物试验研究了溴氰菊酯对克氏原螯虾的96h急性毒性,分光光度法检测了6、12、24和48h后0.01、0.02和0.04μg/L溴氰菊酯对肝胰腺超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活力和丙二醛(MDA)的含量等氧化胁迫相关指标的影响。结果表明,24、48和96h的半致死浓度分别为0.1560、0.0993和0.0562μg/L,安全浓度为5.62ng/L;在整个暴露过程中,溴氰菊酯各个处理组都引起了氧化胁迫相关指标的变化。SOD和CAT活力的变化趋势相同,都呈抑制-诱导-抑制的变化规律,MDA含量则一直高于对照组。暴露6h后,0.01μg/L浓度组MDA含量极显著高于对照组(P<0.01),0.04μg/L浓度组MDA含量约为对照组的1.98倍(P<0.05);暴露12h后,MDA仍保持较高水平,0.02μg/L浓度组MDA含量约为对照组的1.76倍(P<0.05);暴露24h后,各浓度组CAT活力分别比对照组上升了70.98%、73.05%和66.67%(P<0.01);暴露48h后,0.01、0.02μg/L浓度组的SOD活力分别下降了...     

Freshwater Crayfish Growth Under Culture Conditions: Proposition for a Standard Reporting Approach

A review of approaches currently used to measure growth in freshwater crayfish under experimental and pond grow-out conditions is presented. The review examined 206 papers on growth and production of freshwater crayfish of which 34 were selected for detailed investigation. Selection was based on the amount of information provided in the published report and on the species studied. The review was restricted to six crayfish species: Cherax tenuimanus (marron), C. destructor (yabbie), C. quadricarinatus (red claw), Procambarus clarkii (red swamp crayfish), Astacus astacus (noble crayfish), and Pacifastacus leniusculus (signal crayfish). Growth indices reported included instantaneous growth rate (IGR), absolute growth rate (AGR), slope of log weight against time (GRE) and specific growth rate (SGR, IGR100). Studies were performed for varying time intervals under a wide range of stocking densities. Most reports did not express growth rate as an index but simply reported growth in terms of initial and final weights. The range of approaches used to express growth performance in freshwater crayfish growth studies hinders comparisons of growth rate and production findings. It is suggested that the reports of studies of growth performance in cultured crayfish include a growth rate parameter as well as initial and final weights. SGR is recommended as the parameter of choice since it is based on an exponential growth trend which is typically observed in measurements of weight increase with time in cultured juvenile and early adult crayfish.     

蛋白质水平及能量蛋白比对克氏原螯虾生长与蛋白酶活力的影响

用3种不同蛋白质水平及能量蛋白比(E/P)水平饲料投喂克氏原螯虾,分析比较不同饲料对克氏原螯虾生长及蛋白酶活力的影响.试验结果表明,当饲料蛋白质水平为31.86%、E/P为35.85 kJ/g时,克氏原螯虾生长最快.随着饲料蛋白质含的上升, 克氏原螯虾肠蛋白酶活力无显著变化(P＞0.05),肝胰脏、胃蛋白酶活力显著增强(P＜0.05);饲料E/P水平未引起胃、肠、肝胰脏蛋白酶活力的显著变化(P＞0.05),当饲料蛋白质水平为31.47%、E/P为40.42 kJ/g时,克氏原螯虾蛋白酶活力最高.     

克氏原螯虾酚氧化酶部分生化特性的研究

以克氏原螯虾(Procambarus clarkii)酚氧化酶(PO)为材料,采用L-DOPA为反应底物,分光光度计测定不同温度和pH条件下PO活力,研究克氏原螯虾PO的特性,为其免疫学研究及优化PO准确测定方法提供依据。结果显示PO活力最高时的温度为35℃,低于和高于35℃活力逐渐下降,45℃以上活力迅速下降;0℃仍具有最高活力的24%。在pH4.0～9.5内PO均具有活力,鳃组织最佳pH5.5,血清最佳pH6.5。因此测定克氏原螯虾PO活力的最佳参数为温度35℃,pH5.5(鳃)或6.5(血清)。以上结果说明冰浴终止反应法测定克氏原螯虾PO活力会影响结果的准确性,要慎用。     

The biological response of the crayfish Procambarus clarkii to transplantation into California ricefields

The population dynamics of the crayfish Procambarus clarkii was studied in California ricefields to investigate the effects of range extension and to examine its potential for harvest. The species was shown to undergo distinct cycles of activity related to depth, temperature and reproduction. Juveniles were observed to have two peaks in activity during late summer and winter, while adults only had a single peak. Ovarian maturity was found during summer and maximum hatching occurred in late summer and winter. Males matured at 35.8 mm carapace length (CL) on the average, while females matured at 36.5 mm CL. A direct correlation between female egg production and body size was noted. P. clarkii in California were shown to be cued into similar cycles as Louisiana crayfish, even though the timing and extent of the hydrological cycle was considerably different. Breeding activity paralleled the Louisiana crayfish, while winter-spring juvenile growth rates (16.32 mm in 120 days) and biomass (208 kg/ha) were much lower. Crayfish emigration during ricefield draining was found to be substantial (31% of population) and may provide an excellent opportunity for harvest.