Habitat specialization and sensitivity to change in a threatened crayfish occupying upland streams

1. Crayfish are culturally and ecologically important species in freshwater ecosystems, but many are now threatened with extinction, due to threats such as habitat loss. Depending on their habitat selectivity and sensitivity, freshwater crayfish could provide effective targets for stream monitoring, restoration and conservation. This study used repeated field surveys of the threatened Murray crayfish, Euastacus armatus (family Parastacidae), to establish their habitat preferences and sensitivity to habitat loss across mesohabitat and microhabitat scales within upland streams of south‐east Australia. 2. Selectivity analysis revealed that upland populations of E. armatus displayed a strong preference for areas of intermediate water flow velocity, deeper water, and stream beds dominated by boulders and gravel. Variations in E. armatus density among and within the two upland streams aligned with these microhabitat preferences, with best‐subsets analyses revealing that E. armatus abundance hotspots were best predicted by models combining water depth with percentage cover of boulders, gravel and overhanging riparian vegetation. 3. Major shifts in stream habitat condition from 2009 to 2015 (e.g. 32% and 50% decline in boulder and overhanging vegetation cover, respectively) was associated with a 91% decline in E. armatus mean density within glide‐pool mesohabitats. 4. These findings highlight how habitat specialization in threatened crayfish such as E. armatus may render them sensitive to changes in stream habitat condition, and how targeted monitoring, restoration and conservation of their preferred habitats could yield multiple benefits for montane freshwater ecosystems. Copyright © 2016 John Wiley & Sons, Ltd.     

栅藻B38营养成分分析及蛋白质营养价值评价

对栅藻B38的营养成分进行了全面分析,结果表明,栅藻藻粉中油脂含量14%,总糖含量13.86%,粗纤维3.52%,灰分4.28%,蛋白质49.0%,为高蛋白质类微藻。栅藻B38中含有23种脂肪酸。栅藻B38中氨基酸总量为852.58 mg/g,必需氨基酸占总氨基酸的47.45%,必需氨基酸指数为85.42%。两种模式的氨基酸比值系数分较接近,均在65以上;待评价物质的氨基酸品质与模式蛋白的贴近度接近1(0.93和0.88)。栅藻B38中共检测出23种矿物质元素,其中钠、钾、钙、镁、铁、铝含量较为丰富。重金属的含量均低于国家食品卫生标准。栅藻B38中维生素B3(106.02 mg/100 g)和维生素E(540.77 mg/100 g)的量较高。综上,栅藻B38的营养较丰富,可以进一步开发利用。     

养殖与野生大刺鳅不同生长阶段肌肉脂肪酸组成的比较研究

为比较人工养殖大刺鳅与野生大刺鳅肌肉脂肪酸组成的差异,采用气相色谱分析法对养殖和野生大刺鳅幼鱼、鱼种、成鱼肌肉脂肪酸组成及其相对含量进行了检测与分析。结果表明,养殖和野生大刺鳅肌肉中共检出24种脂肪酸,其中不饱和脂肪酸含量较均最高,平均含量分别达到(65.63±1.88)%和(59.03±2.11)%,特别是含有丰富的C18:2、二十二碳六烯酸、二十碳五烯酸和 ,花生四烯酸等多不饱和脂肪酸;ΣUFA/ΣSFA比值从幼鱼到成鱼阶段显上升趋势,且养殖大刺鳅(2.45±0.21)高于野生大刺鳅(1.98±0.15);养殖大刺鳅成鱼阶段的P/S比值达到1.0,超过一般的淡水鱼类。综合分析表明,养殖大刺鳅肌肉品质在脂肪酸组成及均衡性略优于野生大刺鳅,但差异不明显。     

大刺鳅催产效率与积温的相关性研究

[目的]为大刺鳅的规模化繁殖、生产和增殖保护提供科学依据.[方法]通过注射催产激素对亲鱼进行催产,在一定水温(24～27℃)条件下对亲鱼进行人工挤卵,分析积温对大刺鳅产卵量、受精率和孵化率的影响.[结果]不同积温对大刺鳅的人工繁殖效率的影响非常大.若积温高于1 101.0℃ ·h或低于985.5℃·h,均不利于大刺鳅的繁殖;当积温介于1 027.5 ～1 046.0℃·h时,大刺鳅产卵量超过600粒/尾,受精率超过90％,孵化率超过80％.[结论]在进行大刺鳅人工繁殖时,应尽量控制催产积温在1027.5～1046.0℃·h.     

福建省由稚虫养得的春蜓新属新种描述,附对近缘种的讨论(春蜓科,钩尾春蜓亚科)

本文建立东方春蜒属 Orientogomphus Chao 新属,以具突东方春蜒 O.armatus Chao et Xu,sp.nov.新种作为属模式种,对该种稚虫作了描述,并将春蜒科中长期以来分类位置有争议的三个种Onychogomphus circularis Selys(1894)〔=Heterogomphus naninus Foerster(1905),新异名〕,Onychogomphus earnshawi Fraser(1924)和 Onychogomphus aemulus Lieftinck(1937)移入本属。     

生殖季节野生大刺鳅雌雄鱼脂肪酸组成研究

为更好地开展大刺鳅的人工繁殖。采用气相色谱法分别测定生殖季节野生大刺鳅雌雄鱼性腺、肝胰脏和肌肉的脂肪酸组成与含量。研究结果表明,雌雄鱼各组织的SFA、MUFA含量最高的分别是C16:0、C18:1n-9;PUFA在雌鱼各组织和雄鱼的肝胰脏、肌肉中含量最高的是DHA,在精巢中是C22:4n-6;雌鱼卵巢、肝胰脏和肌肉中,含量最高的脂肪酸分别是C18:1n-9（32.65%）、DHA（18.54%）、C18:1n-9（34.99%）;雄鱼精巢、肝胰脏和肌肉中含量最高的脂肪酸分别是C22:4n-6（33.52%）、DHA（45.68%）、C18:1n-9（23.24%）。大刺鳅亲鱼培育可雌雄鱼分池养殖;在雌鱼饲料中添加C18:1n-9、DHA、ARA,可促进卵巢发育,提高卵子质量;给雄鱼投喂添加DHA、C18:1n-9、ARA和C22:4n-6的饲料,能提高精子质量。     

Assay of Biochemical Compositions of Two Indian Fresh Water Eel with Special Emphasis on Accumulation of Toxic Heavy Metals

This study investigated lipid and protein composition of two river eel available in India, Mastacembelus armatus and Anguilla bengalensis bengalensis, to ascertain their nutritional value. The carnivorous nature of eel makes it susceptible for bioaccumulation and biomagnification of toxic metal in their body; therefore, the measurement of two toxic heavy metals, mercury and arsenic, in the muscle tissues of these two eel species was also determined. The results showed that though the lipid content of both the species was quite low in comparison to European or Japanese eel, the protein content was appreciably high, and the value was quite similar in both species (～24%). The fatty acid profile and amino acid profile of the two species were also determined to quantify the amount of essential fatty acid as well as essential amino acid in their muscle tissue. The amount of total mercury, organic mercury, and arsenic was found to be non-remarkable which indicates the beneficial and safe consumption of these species.     

“百草霜”对大刺鳅生长及其酶活性的影响

研究旨在考察饲料中添加不同水平的“百草霜”对大刺鳅生长、消化酶及非特异免疫活性的影响。将野生大刺鳅子一代(Mastacembelus aculeatus)幼鱼随机分成4 组,每组3 个平行,其中1 组为饲喂鳗鲡配合饲料的对照组,另外3 组分别为饲喂添加0.1%、0.5%、1.0%“百草霜”鳗鲡配合饲料的试验组,水温26~28℃,溶解氧5.0~6.0 mg/L,pH 6.5~7.5,饲养周期为56 天。结果表明：与对照组相比,添加0.5%“百草霜”对大刺鳅增重率和特定生长率分别提高了24.76%和16.18%(P<0.05),而0.1%组饲料系数降低了30.23%(P<0.05)。添加“百草霜”未影响大刺鳅成活率(P>0.05)。胃蛋白酶在0.5%组最高(P<0.05);肠道及肝脏淀粉酶活力随着“百草霜”浓度的增大均呈先上升后下降的趋势,其中0.1%组效果最好,与对照组差异显著(P<0.05)。非特异性免疫指标的测定结果显示：添加0.1%和0.5%的大刺鳅肠道超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、酸性磷酸酶(ACP)和碱性磷酸酶(AKP)的活性显著高于对照组(P<0.05),而肝脏过氧化氢酶活性在0.1%组达到最大(P<0.05),各组肝脏SOD、AKP、ACP与对照组无显著差异(P>0.05)。上述研究表明,饲料中添加剂量为0.1%~0.5%的“百草霜”能显著提高大刺鳅酶活性,满足生长需求。     

配合饲料在不同密度大刺鳅精养模式中的应用效果

旨在考察不同养殖密度对大刺鳅生长性能和摄食行为的影响。采用310天的单因素水泥池精养试验对初始密度为657.52 g/m³（A组）、1177.27 g/m³（B组）两组大刺鳅的生长性能及特征进行比较。结果表明：大刺鳅的生长性能与养殖密度呈负相关,其中A组大刺鳅的增重率、特定生长率、肥满度及存活率均高于B组,而饲料系数及单位面积产量分别比B组低13.82%与30.77%。各密度组大刺鳅的体长均与体质量呈幂函数相关（A组：W=0.0028L^3.041;B组：W=0.0049L^2.953）,为等速生长。体长、体质量与养殖天数呈多次函数相关（A组：L=-8×10^-5d²+0.07758d+13.059,W=-2×10^-6d³+0.0011d²+0.1369d+7.2355;B组：L=-6×10^-5d²+0.062d+12.379,W=-2×10^-6d³+0.001d²+0.1031dd+6.8031）。该试验条件适合于大刺鳅的规模化生产,今后应进一步细化大刺鳅的养殖密度,寻找最佳产量与饲料利用之间的关系,争取最大效益。