排序方式： 共有14条查询结果，搜索用时 15 毫秒
1.
J.D. Celada J.M. Carral J.R. Pérez M. Sáez-Royuela C. Muñoz 《Aquaculture International》2002,9(3):269-271
Embryonated eggs of theEuropean native white-clawed crayfish Austropotamobius pallipes Lereboullet weresubjected to three periods of storage usingpolystyrene boxes and, afterwards, artificiallyincubated. At the end of the longest storage(42 days) survival rate was 98.3%, with 65%developed to stage 2 juvenile. Differentstorage periods allowed the staggeredproduction of juvenile batches within a monthperiod. The same containers used for storagewere also suitable for transport. 相似文献
2.
White-clawed crayfish, Austropotamobius pallipes, were endemic to the Nant watershed, Ardéche, France, until they were extirpated by epizootic mortality at the beginning of the twentieth century. A. pallipes were successfully reintroduced to the Nant watershed in the middle of the twentieth century. However, epizootic mortality was observed in the Nant watershed in the summer of 2000 during which time A. pallipes was extirpated from downstream regions. Dead and moribund crayfish were again detected in several episodes in summer 2001 and by October the range of A. pallipes was reduced to the headwaters of just one of the three streams in the watershed. Water quality for the watershed in summer 2001 was appropriate for crayfish habitation. Bacteriology and mycology on A. pallipes collected during several of the mortality episodes in 2001 failed to reveal a cause. However, histopathology revealed a high occurrence of intranuclear eosinophilic inclusions in hepatopancreatocytes of A. pallipes . The nuclei were hypertrophic and contained bacilliform virions consisting of a cylindrical nucleocapsid surrounded by a trilaminar envelope. Virions in section were approximately 63 × 258 nm and nucleocapsids were approximately 52 × 225 nm. It is unclear whether the intranuclear bacilliform virus was the cause of the mortality episodes or was a contributor to a disease complex involving one or several other undetected pathogens. 相似文献
3.
Sara Brusconi Silvia Bertocchi Barbara Renai Massimiliano Scalici Catherine Souty‐Grosset Francesca Gherardi 《水产资源保护:海洋与淡水生态系统》2008,18(7):1227-1239
- 1. As part of the Austropotamobius pallipes species complex, the crayfish Austropotamobius italicus is a species of community interest whose preservation requires the designation of Special Areas of Conservation (SACs) (Annex II, EU Habitats Directive). This study aimed at (1) assessing the conservation status of this threatened indigenous species by stock assessment in central Italy and (2) identifying some aspects of its elective habitat.
- 2. Surveys were conducted in nine streams harbouring A. italicus (streams WI) and in 10 streams where crayfish populations became extinct at least 5 years before the study (streams WO).
- 3. The results confirmed that A. italicus is a K‐selected species, with a relatively slow growth rate (males: 0.34; females: 0.37) and a long life expectancy (males: 8.2 years; females: 7.8 years). The extant populations are healthy, showing balanced sex‐ratios and well structured age‐class compositions. Mortality is mainly due to fishing, which is illegal in Tuscany.
- 4. Principal Components Analyses showed that the streams WI and WO differ in the abundance of allochthonous plant detritus but not in the taxonomic composition of their macroinvertebrate communities. Age classes were found to be spatially segregated, juveniles mainly using cobbles as substrates and adults seemingly avoiding them.
- 5. The loss of the pristine riverine landscape seems to have been responsible, together with illegal fishing, for the local extinction of the species. As a consequence, retaining, enhancing, and restoring the habitat and its complexity are required for the preservation of A. italicus.
- 6. The designation of SACs might help in this endeavour if accompanied by programmes aimed at publicizing the need for conservation of this species. Unfortunately, crayfish‐focused projects supported by LIFE in Italy since 1992 (4%) and the SACs involved (1.4%) have been relatively few, despite the poor conservation status of this species and its well recognized ecological role.
4.
5.
Javier Diéguez‐Uribeondo Félix Royo Catherine Souty‐Grosset Anne Ropiquet Frédéric Grandjean 《水产资源保护:海洋与淡水生态系统》2008,18(1):19-31
- 1. A study on the genetic variability of the white‐clawed crayfish was carried out based on mitochondrial cytochrome oxidase subunit I gene sequences. The sequences applied were more informative regarding white‐clawed crayfish genetic variability than others previously used.
- 2. Two haplotypes were found to exist in the Iberian Peninsula. The haplotypes exhibit a strong geographic subdivision (ΦST=0.83). One of the Iberian haplotype s was similar to north Italian haplotypes and the second differed in only one mutation. This pattern of genetic variability contrasts with those found in glacial refugial areas of France, Italy and the Balkan Peninsula.
- 3. Two hypotheses on the origin of the white‐clawed crayfish in the Iberian Peninsula are discussed: (i) one based on an anthropogenic origin, and (ii) a second based on a successive number of postglacial ancient and recent bottlenecks, i.e. the disjunction between Iberian and Italian populations of white‐clawed crayfish species is due to competition between A. italicus and A. pallipes, in addition to the impact of crayfish plague and human translocations.
- 4. New references for the white‐clawed crayfish in the Iberian Peninsula were found in medieval and Arabic texts. The results show that this species has been thriving in this peninsula since ancient periods and that its indigenous status should not be questioned.
- 5. Conservation action and plans should consider the low genetic diversity as a limitation for farm‐raising specimens more adapted and resistant to changing environments and diseases.
6.
- 1. Spanish populations of the white‐clawed crayfish have declined sharply over the last three decades. Although Austropotamobius pallipes was once widely distributed and very abundant in most of the limestone basins of the country, outbreaks of crayfish plague since 1978 have reduced its populations, and now only some 500–600 small populations are left.
- 2. Consequently, the species now enjoys protection under national legislation. Management decisions regarding the conservation of a threatened species require an understanding of the genetic structure of its populations.
- 3. Using random amplified polymorphic DNA (RAPD) fingerprinting the genetic variability of 11 populations of A. pallipes was assessed over the species' range in Spain, and their phylogenetic relationships determined.
- 4. Substantial genetic differentiation was detected among the populations tested; no clear relationship was found between patterns of genetic variability and hydrological basin. The RAPD markers showed the degree of genetic variability of these populations to be similar to, and in some cases slightly higher than, that reported in previous studies on other Spanish and European populations of A. pallipes.
- 5. The results offer hope for the recovery of this species in Spain, and provide information that might be useful in the management of crayfish reintroduction programmes.
7.
8.
Damian H. Bubb Oliver J. O'Malley Angela C. Gooderham Martyn C. Lucas 《水产资源保护:海洋与淡水生态系统》2009,19(4):448-455
- 1. The North American signal crayfish Pacifastacus leniusculus has been widely introduced throughout Europe where it is expanding its range and in many areas replacing the native white‐clawed crayfish Austropotamobius pallipes. There is concern with regards to the impact of this species replacement on benthic fish. Interspecific behavioural interactions and competition for shelter between the benthic fish, bullhead Cottus gobio and A. pallipes and P. leniusculus were measured to assess the comparative impact of native and non‐native crayfish.
- 2. Both white‐clawed crayfish and signal crayfish were dominant over bullhead. Bullheads moved away from approaches of crayfish, left shelters on entry of crayfish and rarely entered an occupied shelter. Signal crayfish made significantly more aggressive approaches towards bullheads than white‐clawed crayfish.
- 3. Alone, bullheads spent most of their time by day under shelter (median 96%), reflecting a highly entrained behavioural response, which was relaxed by night (median 60%). Both crayfish species reduced shelter use by bullheads although the extent of shelter sharing by bullheads was higher in trials with white‐clawed crayfish than with signal crayfish.
- 4. Sampling in the River Wharfe, northern England, where signal and white‐clawed crayfish and bullhead currently exist, demonstrated a negative relationship between the densities of signal crayfish and bullhead, with high bullhead abundance where crayfish were absent or where white‐clawed crayfish were present at low density.
- 5. Assuming that shelter is sometimes limited under natural conditions, crayfish are likely to displace bullheads from shelters, which may increase predation risk for bullheads. Although the effects of signal crayfish on bullhead shelter use were more intense, the pattern was highly evident for the native white‐clawed crayfish. The higher fecundity and densities attained by signal crayfish may be more significant than differences in the behaviour of the two crayfish species in determining the impact of crayfish on bullheads.
9.
本文对黄足肥螋Euborellia pallipes(Shiraki)的发生及其对苹果绵蚜Eriosoma lanigerum(Hausmann)的捕食作用开展了研究。结果表明:7～9月份是黄足肥螋田间发生高峰期,它对苹果绵蚜E.lanigerum(Hausmann)的功能反应符合HollingⅡ,Na=0.9804N/(1 0.0108N),其捕食量随苹果绵蚜密度的增加而增加,日最大捕食量和最佳寻找密度可达46.3头和19.9头。在15～30℃下,黄足肥螋的捕食量随温度的升高而增加,每头成虫在10、15℃、18℃、20℃、25℃和30℃下的取食量分别为3.3头、20.3头、23.8头、25.8头和27.0头。研究表明了黄足肥螋是苹果绵蚜的主要捕食性天敌昆虫之一,应加强保护与利用。 相似文献
10.