外来鱼类革胡子鲶与本地鲶的功能反应及生物学特性的比较

珠江水系是中国遭受外来水生动物入侵最严重的水域之一,分布有许多种外来鱼类,然而这些外来鱼类对本地鱼类资源的影响尚缺乏有效的评估。比较功能反应被认为是量化外来物种生态影响的有效方法之一。本研究采用控制实验对外来鱼类革胡子鲶(Clarias gariepinus)和本地鲶(Silurus asotus)的功能反应进行了比较。实验以鲮(Cirrhinus molitorella)、广东鲂(Megalobrama hoffmanni)和草鱼(Ctenopharyngodon idellus)的幼鱼为饵料,按照1、2、4、8、16和32条的饵料密度进行投喂,设置3个重复组,研究了革胡子鲶和鲶的功能反应类型,建立了功能反应的曲线,并拟合了功能反应的参数;同时分析了革胡子鲶和鲶的食物转化效率并比较了二者的生物学特性。结果表明:革胡子鲶和鲶的功能反应类型均为Type II型。与鲶相比,革胡子鲶具有更高的单位资源消耗率即更强的袭击率(P0.05),而两种鱼对猎物的处理时间则无显著区别(P=0.272);革胡子鲶的食物转化效率显著低于鲶(P0.05),为鲶的0.57倍,两种鱼的相对生长率则无显著差异(P=0.762)。本研究为系统评估革胡子鲶的生态影响提供基础,同时为量化其他外来鱼类的资源消耗率及潜在的生态影响提供借鉴。     

革胡子鲶GH成熟肽在大肠杆菌中表达条件的优化

将携带革胡子鲶(Clarias lazera)生长激素(GH)成熟肽cDNA序列的重组表达载体pRSET-mGH转化入大肠杆菌Escherichia.coliBL21(DE3)pLysS中进行融合蛋白的表达。表达条件优化试验表明,表达菌株接种SOB培养基,培养2-3h后可用IPTG进行融合蛋白诱导表达;IPTG最佳诱导浓度为1.5 mmol/L,最佳诱导时间为4 h。本试验构建的原核表达体系为下一步革胡子鲶生长激素促生长制剂的研制奠定了基础。     

斑点胡子鲶和胡子鲶染色体组型的研究

斑点胡子鲶(Clarias macrocephalus)又称大头胡子鲶,是近年来从泰国引进的淡水养殖鱼类,它与生长在我国的胡子鲶(Clarias fuscus)形态和习性相近,在分类学上同属鲤形目、胡子鲶科、胡子鲶属。 斑点胡子鲶具有生长较快、体型较大、产量较高的优点,但也有肉味稍逊、耐寒力偏弱、养殖不易的缺点;而胡子鲶的优点是肉质细嫩、味美、抗寒力较强、养殖容易,其缺点是生长较慢、     

嘉陵江南方大口鲶的生物学研究

南方大口鲶(SilurussaldatovtmeridtonalisChen)又名河鲶,在嘉凌江中其最大个体可达30公斤,一般个体2—3公斤。年产量高,与土鲶计算在一起,占全江鱼产量的12.7%,其中河鲶约占8%左右。广元清水河下段,是一个捕捞河鲶的据点,其捕捞量占全部渔获物的10.9%。由于滚钩渔具的使用影响了河鲶的增殖。为此,我们对河鲶的生物学进行了调查研究,为今后改善渔具,稳定产量提供参考。计收集了标本341尾。河鲶有生长快、个体大、肉味肥美的特点,与土鲶一样被列为甲级鱼。在嘉陵江干流及其一级支流中都有河鲶。山溪、渠溪的上段不见此鱼,这与土鲶不同。一、…     

革胡子鲶染色体组型的研究

革胡子鲶(Clarias leather)又称埃及胡子鲶,原产非洲尼罗河流域,1981年我国从埃及引进,经过几年来的试养和人工繁殖均已获得     

革胡子鲶血液常数值的周年变化

在淡水养殖鱼类血液学研究中,有关革胡子鲶血液常数值及其周年变化的资料尚属罕见,而这方面的研究对了解革胡子鲶生物学性状和促进其繁殖均有一定意义。为此,作者以62尾(雌鱼32尾,雄鱼30尾)健康无病、体长均值为 31.55±4.92 厘米、体重均值为 281.33±145.64克、年龄为1—2 周龄的革胡子鲶(Clarias lazera)血液为材料,对其红细胞数(RBC)、白细胞数(WBC)、血红蛋白值(Hb)、比积(Ht)、比重(BSG)、红细胞脆性(Eof)、沉降率(ESR)、白细胞百分式(DLC)和各型血细胞的大小(长径×短径)等常数值分双月进行了周年测定,并分析了性别、繁殖等因素对上述常数值的影响和周年变化的规律。     

白缘(鱼央)性别决定的细胞学证据

白缘(鱼央)(Leiobagrus marginatus)为中小型鱼类,属鲶形目(Siluriformes)(鱼央)科(Amblycipitidae)。1984年5月,我们采用培养细胞制片的方法,对白缘缺的染色体组型进行了分析,结果表明,白缘(鱼央)具有XY((?))-XX(♀)型性     

太湖鱼类的寄生蠕虫:复殖吸虫.——Ⅱ.后睾科等及一新种后睾吸虫的描述

1、本文为太湖鱼类的寄生蠕虫报告之二。 2、本文报告四种寄生鱼体的複殖吸虫,即鲶后睾吸虫Opisthorchis parasiluri,sp.nov.,寄生鲶胆囊;河鲈源吸虫 Genarches goppo(Ozaki,1925),寄生暗色吐(鱼父)胃肠;鲶似单孔吸虫 Paratormosolus siluri Dubinina et Bychovsky,1954,寄生黃颡鱼及鲶肠;朝鲜鲫吸虫 Garassotrema koreanum Park,1938,寄生鲫、平胸鳊、鲤、蒙古鲌、红眼鳟、青魚、花鲢、白鲢、鲩、短尾鲌、(?)条鱼等消化道。四虫分隸四科四属,其中鲶后睾吸虫为新种,馀三种皆为我国的新纪录。     

南方鲶性腺分化的组织学观察

用芳香化酶抑制剂(Fadrozole)、雌激素受体拮抗剂(Tamoxifen)对人工孵化的南方鲶(Silurus meridionalis)幼鱼进行雄性化诱导处理(口服),获得雄鱼。对孵化后第5—130d的南方鲶幼鱼性腺进行组织学观察,结果表明,在实验条件下,南方鲶性腺分化发生在孵化后7d左右,雌雄性分化过程差异明显。雌鱼卵巢腔在孵化后12d左右形成,生殖细胞在孵化后35d左右快速增殖,成熟分裂最早发生在孵化后55d左右;雄鱼生殖细胞在孵化后130d左右快速增殖,成熟分裂最早发生在孵化后130d左右。雌性性腺分化早于雄性。     

华南地区外来鱼类革胡子鲶的繁殖生物学

2011年8月—2015年8月在华南地区主要河流收集255尾革胡子鲶(Clarias gariepinus)样本,对其繁殖生物学特征进行研究。结果表明:革胡子鲶繁殖季节为5—8月,繁殖旺季为6—7月,卵径分布呈现明显的多峰型;成熟系数与脂肪系数和肥满度的周年变化存在相反的趋势;绝对繁殖力为2850~605720粒,均值234232±175498粒,与体长、体重和年龄呈正相关;相对繁殖力为20~445粒·g~(-1),均值165±99粒·g~(-1),随体长、体重和年龄的增加呈先增加后趋于稳定趋势;绝对繁殖力和相对繁殖力均大于常见的鲶科鱼类。繁殖群体性比为1∶1.12,符合1∶1比例;雌、雄鱼最小性成熟个体均为1龄,Ⅳ期性腺;雌鱼体长174 mm,体重119.5 g,成熟系数为8.50%;雄鱼体长205 mm,体重116.2 g,成熟系数为0.45%;繁殖群体以1和2龄鱼为主,分别占繁殖群体总数的42.28%和51.68%,以补充群体占优势;华南地区革胡子鲶野生种群具有分批产卵、相对繁殖力高、卵径小、性成熟年龄低的特征,有利于其迅速建立稳定的种群,应加强对革胡子鲶野生种群动态的监测力度,并进一步采取防控措施。     

Impact of Invasive Water Hyacinth (<Emphasis Type="Italic">Eichhornia crassipes</Emphasis>) on Snail Hosts of Schistosomiasis in Lake Victoria,East Africa

Invasive plants may change ecologic conditions to contribute to transmission of human diseases. This study examined whether water hyacinth (Eichhornia crassipes) had an effect on the snails Biomphalaria sudanica and B. choanomphala, hosts of the disease organism Schistosoma mansoni in Lake Victoria, East Africa. Eight 16-m² enclosures were established in shallow shoreline areas and were paired for water depth, substrate, detrital build up, and distance from rooted vegetation, agricultural runoff, and human activity. In each enclosure, nine randomly selected sediment samples were collected by using a Petite Ponar Dredge, after which 50 water hyacinth rosettes were added to the experimental enclosure within each pair. Six weeks later, nine randomly selected sediment samples were again collected, as were two water hyacinth rosettes from the water column above each sampling point. During the 6 weeks, water hyacinth density had increased from 50 to approximately 2400 rosettes in each enclosure. Adult B. sudanica and unidentified snail egg masses were observed on sampled water hyacinth petioles. Biomphalaria sudanica density was significantly higher in enclosures with water hyacinth (P=0.034); snail size suggested that this difference was due to passive or active immigration rather than increased reproduction, but snail emigration or greater predation in control enclosures may also have contributed.     

Ecological and socio‐economic impacts of invasive water hyacinth (Eichhornia crassipes): a review

1. Water hyacinth (Eichhornia crassipes) is one of the world’s most invasive aquatic plants and is known to cause significant ecological and socio‐economic effects. 2. Water hyacinth can alter water clarity and decrease phytoplankton production, dissolved oxygen, nitrogen, phosphorous, heavy metals and concentrations of other contaminants. 3. The effects of water hyacinth on ecological communities appear to be largely nonlinear. Abundance and diversity of aquatic invertebrates generally increase in response to increased habitat heterogeneity and structural complexity provided by water hyacinth but decrease due to decreased phytoplankton (food) availability. 4. Effects of water hyacinth on fish are largely dependent on original community composition and food‐web structure. A more diverse and abundant epiphytic invertebrate community may increase fish abundance and diversity, but a decrease in phytoplankton may decrease dissolved oxygen concentrations and planktivorous fish abundance, subsequently affecting higher trophic levels. 5. Little is known about the effects of water hyacinth on waterbird communities; however, increases in macroinvertebrate and fish abundance and diversity suggest a potentially positive interaction with waterbirds when water hyacinth is at moderate density. 6. The socio‐economic effects of water hyacinth are dependent on the extent of the invasion, the uses of the impacted waterbody, control methods and the response to control efforts. Ecosystem‐level research programmes that simultaneously monitor the effects of water hyacinth on multiple trophic‐levels are needed to further our understanding of invasive species.     

Water hyacinth,Eichhornia crassipes (Pontederiaceae), reduces benthic macroinvertebrate diversity in a protected subtropical lake in South Africa

The socio-economic impacts of the free-floating aquatic plant water hyacinth, Eichhornia crassipes (Pontederiaceae), on aquatic systems are well documented, yet the impacts on aquatic biodiversity, particularly invertebrate biodiversity, are less well understood. This study aimed to determine whether the presence of water hyacinth altered the diversity and assemblage structure of benthic macroinvertebrates in a conservation area. The benthic macroinvertebrate assemblage was sampled over 1 year at five sites under water hyacinth mats and at five sites without water hyacinth at Lake Nsezi—Nseleni River in the vicinity of Richards Bay, KwaZulu-Natal, South Africa. Artificial substrates were placed beneath water hyacinth mats or in the open water to allow for colonization by freshwater macroinvertebrates, and left for a period of 6 weeks, repeated on seven occasions. Twenty nine families comprising 18,797 individuals were collected, 817 (13 families) individuals were from under water hyacinth mat sites compared to 17,980 (27 families) individuals from open water sites. Ninety-eight percent of individuals collected were, however, the invasive snail, Tarebia granifera. Open water samples were separated from samples beneath the water hyacinth mat by non-metric Multidimensional Scaling, indicating reduced biodiversity associated with the presence of water hyacinth. Exclusion of the dominant Thiaridae from the analysis did not alter the groupings. Family richness(s) and abundance (N) were significantly higher in open water communities(S: H₃ = 21.09; P = 0.0001; N: H₃ = 22.58; P = 0.00001), while evenness (J’) was higher under water hyacinth mats (H₃ = 20.13; P = 0.0002). The presence of water hyacinth had a significantly negative impact on aquatic macroinvertebrate biodiversity in a conservation area, and therefore the control of this invasive aquatic plant must play a major role in catchment management.     

Plant community dynamics relative to the changing distribution of a highly invasive species, <Emphasis Type="Italic">Eichhornia crassipes</Emphasis>: a remote sensing perspective

Eradicating or controlling invasive alien species has frequently had unintended consequences, such as proliferation of other invasive species or loss of ecosystem function. We explore this problem using a case study of a highly invasive floating aquatic macrophyte, water hyacinth (Eichhornia crassipes), in the Sacramento-San Joaquin Delta of California. We used 5 years of remote sensing data to perform change detection analysis to study plant community dynamics contemporaneous with changes in water hyacinth cover. Our results show that as water hyacinth cover decreased, submerged aquatic plant (SAP) cover increased and vice versa. This effect was strongest in large patches of water hyacinth. We found no evidence that the native floating aquatic species, pennywort (Hydrocotyle umbellata), benefitted from reducing cover of water hyacinth. In most years, pennywort cover either showed no trend or followed the same trajectory as water hyacinth cover. In this study a decrease in cover of water hyacinth most often resulted in colonization by SAP species with some habitat returning to open water.     

Herbivory on aquatic vascular plants by the introduced golden apple snail (<Emphasis Type="Italic">Pomacea canaliculata</Emphasis>) in Lao PDR

The effect of naturally found densities of the exotic and herbivorous golden apple snail (Pomacea canaliculata) on three dominant aquatic plants – duckweed (Lemna minor), water hyacinth (Eichhornia crassipes) and morning glory (Ipomoea aquatica) – was assessed in a wetland survey and quantified in a field experiment in Laos in southeast Asia. Snail grazing reduced plant biomass, but plant species were differently affected by grazing. Duckweed had almost disappeared after 6 and water hyacinth after 21 days, whereas morning glory remained at 80% of initial biomass after 32 days. Snail growth was lowest on morning glory and, when all plant species were simultaneously presented to snails, this plant was not preferred. We suggest that the negative effect the golden apple snail had on the growth of these plant species in field enclosures is present in the natural environment as well. This new and intense herbivory could have serious negative effects on invaded freshwater ecosystems in this region.     

The feeding activity of Colossoma macropomum larvae (tambaqui) in fishponds with water hyacinth (Eichhornia crassipes) fertilizer.

Analysis of macrophyte water hyacinth (Eichhornia crassipes) as an organic fertilizer of Colossoma macropomum (tambaqui) larvae in ponds is provided. Water hyacinth produce an organic fertilizer at the ratio of 100 g x m(-2) in tambaqui ponds. Two groups of 5,000 larvae were transferred to two fishponds with and without water hyacinth fertilizer and reared until day 43. The fertilized pond evidenced more plankton abundance during the entire production period when compared with the control pond (P < 0.001). The phytoplankton community in the pond was not significantly different than in gut contents (P > 0.05) in both ponds (with and without organic fertilizer). Fish larvae failed to show any preference or selectivity in relation to the different algae (P > 0.01) in the pond, but exhibited high ingestion selectivity for zooplankton (P < 0.05). Application of fertilizer increased (P < 0.05) the abundance of phytoplankton and zooplankton in the treatment pond. Since water hyacinth fertilizer is quite cheap and easily available, it may be conveniently used to enhance fish yield in ponds.     

基于Miseq测序技术分析黄颡鱼不同养殖模式下池塘微生物群落结构多样性

利用Miseq测序技术分析了黄颡鱼Pelteobagrus fulvidraco (Richardson)三种养殖模式[(黄颡鱼单养、黄颡鱼混养草鱼(Ctenopharyngodon idellus, Valenciennes)和黄颡鱼混养草鱼、鳙(Aristichthys nobilis, Richardson)、鲢(Hypophthalmichthys molitrix, Valenciennes)]下养殖水体及底泥微生物群落结构多样性。结果显示, 12个样本共获得了655100条合格16S rDNA序列, 每个样本获得的有效序列数目为41256—77508, 可归纳为608—3686个分类操作单元。α多样性指数结果表明, 在三种养殖模式下末期水体的微生物群落丰度和多样性均高于养殖初期, 黄颡鱼混养草鱼模式下水体的群落丰度最高(Chao1指数: 2199.25, ACE指数: 2374.60), 黄颡鱼混养草鱼、鲢、鳙模式下水体微生物群落多样性最高(Shannon指数: 4.88, Simpson指数: 0.021)。样本聚类分析及PcoA主坐标分析结果表明, 黄颡鱼单养及黄颡鱼、草鱼混养模式下的水体和底泥的菌群组成及群落结构相似性较高, 黄颡鱼、草鱼、鲢、鳙混养模式下样本单独形成一类。从门水平的比较分析发现, 所有样本检测到细菌有8门, 其中变形菌门(Proteobacteria)的物种丰度在所有样本中占绝对优势地位。放线菌门(Actinobacteria)在养殖末期升高成为水体中占比第二的优势门, 尤其是黄颡鱼混养草鱼模式下(37.6%)。黄颡鱼在单养模式下, 养殖末期水体拟杆菌门(Bacteroidetes)细菌含量均明显增加(1.95%到10.98%)。从属水平的比较分析发现, 各样本之间的优势属组成有较大差异, 其中黄颡鱼在单养模式下水体样本中气单胞菌属(Aeromonas)在养殖末期丰度占优势(5.81%)。从微生物群落结构和多样性的角度考虑, 黄颡鱼、草鱼、鲢、鳙混养是一种值得推荐的养殖模式。     

入侵植物凤眼莲研究现状及存在的问题

 凤眼莲(Eichhornia crassipes)原产南美洲,被列为世界十大恶性杂草之一,现已入侵了非洲、亚洲、北美洲、大洋州、甚至欧洲等5个大洲,至少62个国家和地区都受到了凤眼莲入侵的危害。凤眼莲的入侵已经引起了一系列的生态、经济、社会问题：首先,它改变了当地水体生态系统的物理、化学环境,进而影响水体生态系统的生物多样性,破坏食物链、物质循环等生态过程的正常运行;其次,凤眼莲造成当地经济的重大损失,航运、渔业、水利等都受到了危害;再次,凤眼莲的入侵爆发也对当地居民饮水、健康等造成威胁。目前,对于凤眼莲的控制及其治理主要有物理的、化学的、以及生物的等3种方法。利用天敌、病菌、以及化感作用等的生物控制被许多专家和学者推崇,同时,利用生物控制凤眼莲入侵也日益成为研究的热点。但是,综合目前对于凤眼莲的认识和研究,仍然具有片面性,需要从生物特性、种群生态、生态系统等方面深入研究凤眼莲入侵机制。而利用生物控制凤眼莲的研究和技术尚不完善,需要进行种间竞争、捕食及遗传变异等方面的探讨和研究。通过总结控制凤眼莲各种方法的长处和不足,最后指出利用生物的方法,并结合污水治理、水系宏观调控及监测等方法,综合治理凤眼莲,是十分必要的,而且也是最具有前景的。     

Experimental and kinetic modelling studies on the acid-catalysed hydrolysis of the water hyacinth plant to levulinic acid

A comprehensive experimental and modelling study on the acid-catalysed hydrolysis of the water hyacinth plant (Eichhornia crassipes) to optimise the yield of levulinic acid (LA) is reported (T=150-175 degrees C, [Formula: see text] , water hyacinth intake=1-5wt%). At high acid concentrations (>0.5M), LA was the major organic acid whereas at low acid concentrations (<0.1M) and high initial intakes of water hyacinth, the formation of propionic acid instead of LA was favoured. The highest yield of LA was 53mol% (35wt%) based on the amount of C6-sugars in the water hyacinth (T=175 degrees C, [Formula: see text] , water hyacinth intake=1wt%). The LA yield as a function of the process conditions was modelled using a kinetic model originally developed for the acid-catalysed hydrolysis of cellulose and good agreement between the experimental and modelled data was obtained.     

Potential impacts of water hyacinth invasion and management on water quality and human health in Lake Tana watershed,Northwest Ethiopia

Incursion of water hyacinth, Eichhornia crassipes, has been a potential threat to Lake Tana and its ecosystem services. Its expansion is currently managed by abstraction (removing by hand); nonetheless, the disposal of mats and formation of pools are remaining problematic. This study aimed to assess the potential effects of water hyacinth and its management on water quality and human health. Biotic and abiotic data were collected on open water, water hyacinth covered and water hyacinth cleared out habitats. A total of 3673 invertebrates belonging to twenty-one families were collected from 45 sites. Culicidae was the most abundant family accounting (37.2%), followed by Unionoidae (19.4%) and Sphaeriidae (8.1%). Abundance of anopheline and culicine larvae were significantly higher in water hyacinth cleared out habitats (p?<?0.05). Water conductivity and total dissolved solids were significantly higher in habitats covered with water hyacinth (p?<?0.05). In conclusion, water hyacinth infestation had a negative impact on water quality and biotic communities. The physical abstraction of water hyacinth provided a very good habitat for the proliferation of mosquito larvae. Therefore, integrating water hyacinth management practices along with mosquito larvae control strategy could help to abate the potential risk of malaria outbreak in the region. In addition, developing watershed scale nutrient management systems could have a vital contribution for managing water hyacinth invasion in the study area.