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1.
Sylviane Gony 《International Review of Hydrobiology》1990,75(6):835-836
Freshwater-adapted glass eels have been exposed to cadmium (5 mg/l) for 3 days and then transferred in clean water for 28 days. Perturbations occurred very early (after 2 hrs only of exposure to cadmium) and concerned mainly the respiratory epithelium: the epithelial cells were very swollen and they showed an important dilation of the endoplasmic reticulum and nuclear membrane. After the decontamination period, signs of recovery appear. Perturbations of osmo-regulatory and respiratory processes are suggested. 相似文献
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The pigmentation development process of glass eels Anguilla anguilla from stage VB to VIA3 was modelled by gamma cumulative functions. These functions varied with respect to the factors temperature and salinity whose effects were adjusted by beta functions. Temperature was shown to accelerate pigmentation, while salinity acted as a secondary factor slowing down the pigmentation. The model fits the development of 15 samples kept at various temperatures and salinities in the Vilaine River, as well as samples monitored at other dates and places in Europe. It allows the prediction of the duration of estuarine residency for glass eels, in winter and spring, in the Atlantic estuaries. 相似文献
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Environmental factors affecting migration of the European eel in the Rivers Severn and Avon, England 总被引：6，自引：0，他引：6
Studies were conducted during 1991–1993 on environmental factors affecting the upstream migration of eels in the Rivers Severn and Avon, England. Migrants (> 156 000 pigmented elvers and > 189 000 juveniles) were trapped as they attempted to ascend weir or sluice barriers. Multiple regression models were developed to compare catches per trap per night (C) with data for various key environmental parameters at seven sites, from the tidal limit to a maximum of 42.5 km upstream. The key stimulus for migration of both elvers and juveniles at the tidal limit was water temperature, with some weaker monthly influences related to seasonal temperature increases. Smaller annual influences probably related to earlier glass eel recruitment into the lower estuary. A weak early tidal effect was demonstrated only once, in 1993 in the Severn. Temperature also exerted significant effects on C of juvenile eels at the tidal limit and in the non-tidal rivers, although effects weakened with distance upstream. Year, month, river flows and whether traps were mounted on weirs or sluices made only small contributions at a few sites. Distance between traps also contributed to combined data for upper Severn sites. The threshold temperature in all cases was 14–16°C, with low to zero catches below 10–11°C, catch maxima being achieved above 18–20°C. The implications of strong temperature-dependence of migration in relation to stock recruitment and management are discussed. Special reference is made to recent decreases in recruitment of eels to Europe and N. America and possible long-term effects of global warming. 相似文献
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Magnetization measurements of the European eel Anguilla anguilla demonstrated the presence of magnetic material concentrated in the region of the mandibular canals of the lateral line system. The data suggest that the material is magnetite, has a size suitable for magnetoreception and is of biogenic origin. The presence of magnetic particles in the lateral line system is discussed in relation to their possible role in allowing the fish to orientate with respect to the geomagnetic field during their extensive oceanic spawning migrations. 相似文献
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The arrival pattern of glass eels of the shortfin eel Anguilla australis and longfin eel Anguilla dieffenbachii was studied over a two successive migration seasons in the Grey River, South Island, New Zealand. Fishing was carried out on selected nights during September to November, for 3 h per night during 2000 and 2001. The number of shortfin glass eels exceeded longfins in both years; earliest glass eels (September) were larger than later glass eels (November), and longfins larger than shortfins, but there were significant differences in size between years for both species. Environmental variables affecting recruitment differed between years, but common variables for both years were sampling date, time after high tide (incoming tide preferred), time after sunset and moon phase; the influence of moon phase appeared to be expressed both through tides (spring tides preferred) and moonlight. During the year of higher discharge variability, both increasing discharge and increased turbidity were also important. 相似文献
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Magnetosensitivity of the Japanese eel Anguilla japonica at the glass eel phase (newly metamorphosed juveniles) was examined by conditioning and electrocardiography. The glass eels were conditioned to an imposed magnetic field of 192 473 nT parallel to the fish body placed along the earth's west‐east axis. After 10 to 40 conditioning runs, all the glass eels exhibited a significant conditioned response ( i.e . slowing of the heart beat) to a 192 473 nT magnetic field and even to a 12 663 nT magnetic field that combined with the geomagnetic field (32 524 nT) at the laboratory and produced a resultant magnetic field of 21° easterly. These results indicate that glass eels have high magnetosensitivity and probably acquire geomagnetic information early in life. It is hypothesized that silver‐phase adult eels find their way back to the oceanic spawning ground by reversing the geomagnetic direction that had been detected and 'memorized' during the glass eel phase when migrating from the open ocean towards the continental shelf and coastal waters. 相似文献
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The occurrence of Phyllodistomum folium in a population of eels was studied throughout one year. Abundance exhibited a summer peak. Gravid adults were found in all months, indicating that eels can serve as a definitive host for this parasite. 相似文献
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Glass eels reacted chemotactically towards five non-protein constitutional amino acids, D-glutamine, D-asparagine, D-glutamic acid, D-alanine and β -alanine, dissolved in fresh water or salt water, with behavioural thresholds ranging from 10-9 M for the most effective (D- and β ;-alanine) to 10-7 M for the other three. With the exception of D-asparagine in fresh water and D-alanine at concentrations ≥10-7 M, these amino acids were strong attractants. The results are compared with previous findings on the respective L-isomers. The non-protein amino acids may influence behaviour in the search for food and the recognition of conspecifics. 相似文献
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P. Melià † D. Bevacqua A. J. Crivelli ‡ J. Panfili § G. A. De Leo ¶ M. Gatto 《Journal of fish biology》2006,69(4):1228-1235
Body growth parameters, age and total length at sex differentiation were compared in three European eel Anguilla anguilla populations from Mediterranean sites with different salinity. Whilst body growth was faster in brackish than in freshwater environments, the present analysis shows that body size at sex differentiation might be a physiological invariant. 相似文献
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A. Okamura H. Zhang† T. Utoh A. Akazawa Y. Yamada N. Horie N. Mikawa S. Tanaka H. P. Oka 《Journal of fish biology》2004,64(5):1450-1454
Interspecific hybrids were obtained by artificial insemination between male European eels Anguilla anguilla and female Japanese eels Anguilla japonica . The hybrid larvae developed normally and survived up to 30 days post‐hatching similarly to normal A. japonica larvae. 相似文献
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A. Acou † T. Robinet ‡ E. Lance § C. Gerard § B. Mounaix &#; L. Brient § B. Le Rouzic § E. Feunteun ‡ 《Journal of fish biology》2008,72(3):753-762
Thirty migrating silver eels Anguilla anguilla were collected in a river system where algal blooms occurred yearly. Fifty per cent of eel livers were contaminated by microcystin-LR (mean ± s . d . toxin level: 28·1 ± 22·4 ng g−1 ). Contaminated silver ( v. healthy) eels had lower fish condition. Consequences of this impact for the breeding potential of these migrating eels are discussed. 相似文献
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S. R. Crean J. T. A. Dick† D. W. Evans‡ R. W. Elwood R. S. Rosell§ 《Journal of fish biology》2003,62(2):482-485
Anal redness in European eels Anguilla anguilla is related to the prevalence and mean abundance of the swimbladder nematode Anguillicola crassus and may provide a simple, non-invasive diagnostic tool for A. crassus infection. 相似文献
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欧洲鳗鲡外周血细胞的显微和超微结构 总被引：31，自引：0，他引：31
利用光镜和透射电镜技术研究了欧洲鳗鲡（Anguilla anguilla）外周血细胞的显微和亚显微结构。结果表明：在外周血细胞中可以区分出红细胞、单核细胞、大淋巴细胞、小淋巴细胞、嗜中性粒细胞和血栓细胞;嗜中性粒细胞内的特殊颗粒包括A、B、C三型;嗜中性粒细胞分为Ⅰ型粒细胞（内含A、B、C三种特殊颗粒）、Ⅱ型粒细胞（内含A型和C型两种特殊颗粒）和Ⅲ型粒细胞（内含C型特殊颗粒）。还见到幼稚的和正在分裂的红细胞和单核细胞,提示示幼稚的红细胞能直接进入外周血流中,嗜酸性粒细胞和嗜碱性粒细胞无论在血涂片上或超薄切片上均未见到。描述了上述各种血细胞在光镜和电镜观察下的形态和细微结构。血栓细胞体积最小,嗜中性粒细胞体积最大;淋巴细胞数目最多,嗜中性粒细胞数目最少。 相似文献
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Otolith Sr:Ca ratios were examined to evaluate the contribution of the stocked eel Anguilla anguilla elvers, which have been stocked in Lithuanian waters and mixed with naturally recruited eels for several decades, to the native eel population. Stocked eels were identified by the freshwater signature (Sr:Ca ratios <2·24 × 10−3 ) on the otolith after the glass eel stage. Naturally recruited eels, that had migrated through the North and Baltic Seas, were characterized by an extended seawater and brackish-water signature (Sr:Ca ratios >3·23 × 10−3 ) after the glass eel stage. Of 108 eels analysed, 21 eels had otolith Sr:Ca ratio profiles consistent with stocking while 87 showed patterns of natural recruitment. The ages of naturally recruited eels arriving in Lithuanian fresh waters varied from 1 to 10 years, with a mean ± s.d . age of 5·2 ± 2·1 years. Eels from the inland Lake Baluošai were all freshwater residents of stocked origin. Stocked eels, however, accounted for only 20% of the eels from the Curonian Lagoon and 2% of eels sampled in Baltic coastal waters. This finding does not support the hypothesis that the eel fishery in the Curonian Lagoon depends mostly on stocking. 相似文献
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The behavioural responses of glass eels of Anguilla anguilla towards amino acids were investigated by binary choice experiments testing different concentrations of 14 L-amino acids in fresh water and salt water. Glass eels responded to solutions of individual amino acids down to a concentration of 10−8 M, 10−9 m. Media of different salinities influenced the responses. In freshwater, gln and thr were strongly attractive; asn, ala, met, glu and ile induced significant avoidance; gly elicited multimodal reactions depending on concentrations; his, lys, phe, val, leu and asp hardly influenced behaviour. In salt water, only gly, asn and lys significantly influenced the behaviour of the glass eels. 相似文献
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L. Pérez J. F. Aturiano A. Tomás S. Zegrari R. Barrera F. J. Espinós J. C. Navarro M. Jover 《Journal of fish biology》2000,57(6):1488-1504
Weekly injections of human chorionic gonadotropin (hCG; 1·5 IU g−1 W ) induced spermiation in 87–100% farmed male European eels Anguilla anguilla over a 10-week period, producing 3 ml (100 g)−1 milt volume, at 1˙4×109 spermatozoa ml−1 sperm mobility peaked in ninth week of treatment with 97% of males with motile sperm. Gonadotropin-treated males showed earlier but similar morphological changes to control males. Whereas higher sperm density was obtained 6 h after hCG administration, higher percentage of motile cells and longer sperm mobility were observed 24 h after the treatment indicating that this is the optimum time to obtain good sperm after the hormonal induction. Several monounsaturated fatty acids in sperm increased significantly from week 5 to 9 of treatment (when highest volume, density and mobility of milt were recorded), whereas eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total n-3 polyunsaturated fatty acids (PUFAs) were significantly reduced. Fatty acid levels returned to initial values after 13 weeks of treatment. These results are in agreement with the reduction of n-3 PUFAs recently observed in the ovary of female Japanese eel during artificial maturation, and an attempt is made to suggest a physiological explanation of its possible relation with sperm quality. 相似文献