The status of the recently introduced fish Leucaspius delineatus (Cyprinidae) in Great Britain

Abstract The fish Leucaspius delineatus (Heckel) (Cyprinidae) has been introduced to southern England as a result of importation as an ornamental fish. It is now established at several waters (lakes, canals, and lowland rivers) in Hampshire and Somerset. It appears to be well adapted to spread beyond these centres as a result of its small size at sexual maturity and reproductive biology. A preliminary assessment of its diet and fecundity, and notes on its breeding habits are given.     

The amount of calcium in bony structures used for age determination in Cyprinion macrostomus (Heckel, 1843)

In this study, the ages of 76 individuals belonging to the Cyprinion macrostomus (Heckel, 1843) population caught from Murat River near Bingöl city were determined from six different bony structures and the level of calcium mineral of each bony structure was measured using an atomic absorption spectrophotometer. The determined element was statistically examined according to the age, length, weight and sex of the fish. The age, length and weight ranges of the fish were found to be 2–6, 12.0–21.2 mm and 16.3–135.3 g respectively. The relationships between the accumulation of calcium in all bony structures and the fish size (both length and weight) were found to be insignificant (P>0.05). However, a strong relationship was found between fish weight and accumulation of the mineral in vertebra and otolith. A strong correlation was also found between fish length and accumulation of calcium in the dorsal fin ray, followed by the otolith, vertebra and cleithrum bones respectively. Whereas the accumulation of calcium according to the age groups was found to be insignificant for scale and operculum (P>0.05), it was found to be significant for all the other bony structures examined (P<0.05). In conclusion, the accumulation of calcium on some bony structures of C. macrostomus was observed to increase with an increase in age, length and weight of fish, although the increases were not statistically significant at least for some bony structures (P>0.05).     

Optimization of feeding quantity and frequency to rear the cyprinid fish Garra rufa (Heckel, 1843)

Garra rufa has a high commercial value, but their rearing methods are still unknown. Aspects like an adequate daily dose and feeding frequency need to be investigated. This work aimed to establish the optimal feed dose per day to obtain satiation and the optimal frequency of feeding to rear a specific size class of G. rufa. A total of 60 fish were distributed by six aquaria containing 10 fish. First, the fish were fed twice per day, by providing a feed dose correspondent to 1% of their body weight and increasing 0.1 g/fish on the following days, until finding feed leftovers on the next morning. Afterwards, the fish went through a 1 month experimental trial to evaluate the optimal feeding frequency. Fish growth was compared between feeding the optimal daily dose distributed in two or three feeding moments per day. The optimal dose that ensured satiation was 0.042 g fish^?1 day^?1 (3.2% of fish’ body weight). Feeding the fish three times per day promoted higher growth rates, since the fish’ total length was statistically different between feeding frequencies. Statistically significant differences between feeding frequencies were not observed for growth performance parameters. These results contribute to the aquaculture of this target species, allowing fish industry to more efficiently respond to the high demand for G. rufa and, simultaneously, for its preservation in the wild.     

Evidence of fish and human pathogens associated with doctor fish (Garra rufa,Heckel, 1843) used for cosmetic treatment

Doctor fish (Garra rufa, Heckel, 1843) are increasingly used for cosmetic treatment raising particular concerns regarding the potential transmission of infections to clients. Investigations of microbial causes undertaken in two outbreaks of mortality among G. rufa used for cosmetic treatment revealed the presence of multiple bacteria, including both fish and human pathogens such as Aeromonas veronii, A. hydrophila, Vibrio cholerae, Shewanella putrefaciens, Mycobacterium marinum and M. goodii. This range of bacteria indicates an intense microbial proliferation involving multiple pathogens, most likely induced by the poor health condition of the fish. Most of the detected pathogens are well‐known agents of zoonosis. Indeed, M. goodii is an emerging nosocomial human pathogen that has never been detected in fish to date, nor in other animals. This first detection of M. goodii associated with fish infection points out a new zoonotic potential for this pathogen. These findings point out that handling, poor environmental conditions and the presence of fish pathogens, that can compromise the immune system of fish, can result in a mixed microbial proliferation and increase the spread of waterborne bacteria, including zoonosis agents. Accordingly, the microbiological surveillance of fish used for cosmetic treatment is extremely important, particularly in association with mortality outbreaks.     

仿刺参基因组大小的测定

仿刺参基因组大小测定采用流式细胞术,以鸡红血细胞DNA含量(2.5 pg/2C)为内标,用夏眠、正常和野生3个群体的仿刺参体腔细胞测定了52只刺参的单倍体基因组含量,其C-值为(0.90±0.06)pg,由此得出仿刺参基因组大小为(880.2±58.68)Mb。其中,夏眠、正常和野生群体C-值分别为(0.93±0.05)、(0.90±0.05)和(0.84±0.02)pg。运用独立样本t检验对比分析显示:(1)夏眠与正常的仿刺参基因组大小之间差异不显著,说明仿刺参基因组大小与夏眠这一生理因子不具有相关性;(2)池塘(围堰)养殖环境下与野生环境下的仿刺参基因组大小之间有显著差异,野生环境下的仿刺参基因组明显小于池塘(围堰)养殖环境下的基因组。据此推测,环境因子的改变可能对仿刺参乃至整个海参类群基因组DNA含量产生影响。实验还对C-值测定的发展和方法作了详尽的描述,同时在综合其他种类海参基因组大小研究的基础上,探讨了C-值与进化地位之间的关系。     

Intercohort cannibalism and parturition-associated behaviour of adult swordtail, Xiphophorus helleri Heckel (Pisces: Poeciliidae)

The post‐parturition behavioural patterns of adult Xiphophorus helleri (Heckel) were described and quantified by recording their duration and/or frequency in glass tanks. All births occurred in the dark. Female behaviour might increase the chance of newborn juvenile survival: at the top of the tank, where juveniles are more vulnerable to predation, the females gave birth in the artificial refuge, while no parturition took place in the refuge at the bottom. Birth‐giving females were no less cannibalistic than males and other females. There was a reduction in cannibalism and the frequency of secondary attacks with time, even though the number of juveniles in the tank continued to increase due to ongoing parturition. Most adults were found at the bottom of the water column during the first 500 min of parturition, after which they were distributed equally in the water column. The movement of adults, away from the bottom and consequently away from the juveniles corresponded with an increase in feeding on alternative food and a reduction in cannibalism. Thus, cannibalism in swordtail might be opportunistic predation.     

关于淞江鲈学名和模式产地以及地理分布之探讨

淞江鲈学名Trachidermus fasciatusHeckel,1840,我国鱼类学文献沿用至今,属名有误,因其阴性Trachiderma早已为其它动物先据而失效。订正后的属名Trachiderm is是有效名称,淞江鲈的学名应写作Trachiderm is fasciatusHeckel,1840。模式产地菲律宾记录有问题,自1840年迄今,菲律宾未见再有该鱼之报道,淞江鲈个体发育水温不宜超过14℃,否则导致胚体畸形和死亡,菲律宾地处热带,气温年平均26.6℃左右,淞江鲈不可能得以繁衍。该鱼为西北太平洋所特有,仅分布于中国、朝鲜半岛和日本南部,我国分布于黄渤海和东海沿岸以及沿岸诸河下游及河口。     

Biology and invasive potential of the introduced swordtail Xiphophorus hellerii Heckel (Poeciliidae) in Western Australia

• 1. The swordtail Xiphophorus hellerii is a popular ornamental freshwater fish that occurs as an introduced species in the aquatic habitats of at least 31 countries. Although introduced populations are found in other Australian states, the only known Western Australian population occurs in the Irwin River (29°15′S).
• 2. The biology of X. hellerii in the Irwin River in south‐western Australia is described from four seasonal samples, collected by seine net, between spring 2002 and winter 2003.
• 3. Pregnant females were collected in all seasonal samples, though juveniles were absent in spring, implying that juvenile mortality during late winter is high. Although mean length of pregnant females (38.7 mm) and mean gonadosomatic index (GSI) (14.7) were similar to reported data for X. hellerii populations in Queensland, mean fecundity was markedly lower in Western Australia, i.e. 34.1, cf. 60.15.
• 4. Logistic analysis of the percentage of female and male X. hellerii with developing and mature gonads predicted that the length at which 50% of the sexes mature was 30.8 and 31.5 mm SL, respectively. The sex ratios of females to males did not differ statistically from a ratio of 2:1.
• 5. The diet of all X. hellerii size classes was omnivorous (primarily vegetal matter/algae), although a significant difference was observed between the diet of juveniles and that of the two larger size classes (i.e. juveniles consumed greater quantities of aquatic invertebrates).
• 6. A melanic polymorphism (i.e. pigmented caudal peduncle and fin) was observed in approximately 5% of X. hellerii collected.
• 7. If released, the range of X. hellerii is likely to expand in anthropogenically modified habitats in tropical and temperate latitudes of Western Australia. Potential ecological impacts on indigenous fishes may be magnified owing to the depauperate nature of the endemic ichthyofauna including a lack of predators. Copyright © 2011 John Wiley & Sons, Ltd.

     

Intercohort cannibalism and post-partum behaviour of juvenile swordtail Xiphophorus helleri Heckel (Pisces: Poeciliidae)

Newborn (i.e. neonate) swordtail Xiphophorus helleri Heckel attempted to escape cannibalization attempts in a downward direction more frequently than in any other direction. The downward escape response is likely to be anti‐predator behaviour. In addition, neonates were often able to escape cannibalization at the time of birth, despite no previous exposure to predators, which suggests that this anti‐predator behaviour is innate. However, neonates at the time of birth were more vulnerable to cannibalism than older juveniles, which supports the hypothesis that anti‐predator behaviour is, at least in part, further developed as a result of previous experience (i.e. learning).     

Further evaluation of the efficacy of emamectin benzoate for treating Pseudocapillaria tomentosa (Dujardin 1843) in zebrafish Danio rerio (Hamilton 1822)

Pseudocapillaria tomentosa is a pathogenic nematode parasite, causing emaciation and severe inflammatory lesions in the intestines in zebrafish Danio rerio (Hamilton 1822). Emamectin benzoate is commercially available analogue of ivermectin used for treating salmon for sea lice, under the brand name SLICE^®, and we have used this for treating zebrafish with the P. tomentosa. Here, SLICE^®, 0.2 per cent active emamectin benzoate, was used for oral treatments at 0.35 mg emamectin benzoate/kg fish/day for 14 days starting at 7 days post‐exposure (dpe). Another experiment entailed initiating treatment during clinical disease (starting at 28 dpe). Early treatment was very effective, but delaying treatment was less so, presumably due to inappetence in clinically affected fish. We evaluated emamectin benzoate delivered in water, using Lice‐Solve? (mectinsol; 1.4% active emamectin benzoate) in two experiments. Application of four 24‐hr treatments, space over 7 days was initiated at 28 dpe at either 0.168 or 0.56 mg emamectin benzoate/L/bath, and both treatments completely eradicated infections. This was 3 or 10 times manufacture's recommended dose, but was not associated with clinical or histological side effects.     

Age determination and growth of juveniles of the European hake,Merluccius merluccius (L., 1758), in the northern Tyrrhenian Sea (NW Mediterranean)

The aim of the present study was to provide an estimation of growth of juvenile European hake, Merluccius merluccius (L., 1758) (OSTEICHTHYES; MERLUCCIIDAE), by means of the analysis of otolith daily increments. Hake specimens were collected during trawl surveys carried out in the northern Tyrrhenian Sea (NW Mediterranean). The sagittae were removed from hakes ≤20 cm total length. Left otoliths were ground and polished to obtain thin frontal sections. Otolith microstructure was analysed under a compound green light-polarising microscope. A power curve with intercept was fitted to the length-age data to describe the growth of M. merluccius. According to the growth curve, a mean length of 18 cm was reached at the end of the first year of life. The validation of the otolith increment periodicity was performed by means of two indirect methods.     

Resource partitioning between Siberian sculpin (Cottus poecilopus Heckel) and Atlantic salmon parr (Salmo salar L.) in a sub-Arctic river, northern Norway

Abstract– Food resource partitioning between Siberian sculpin ( Cottus poecilopus ) and Atlantic salmon parr ( Salmo salar ) was investigated throughout a summer season in the subarctic River Reisa, northern Norway. The two species had almost identical diets, feeding primarily on benthic invertebrates and selecting the same prey species. There was no strong segregation in the diel feeding rhythms of the two species, although the salmon parr consumed a large proportion of their food at night during August and September. The results suggest that the two species compete for food, and that interspecific competition for limited food resources may explain the low production of Atlantic salmon in this river. The observation of a high degree of dietary overlap between the sculpin and the salmon parr contrasts with expectation of interactive segregation. Further, the findings conflict with general niche and competition theories, being inconsistent with the competitive exclusion principle.     

The Influence of Livefeed Supplementation on Growth and Reproductive Performance of Swordtail (Xiphophorus helleri Heckel 1848) Broodstock

The influence of supplementation of drum-dried flake feed with various levels of Daphnia sp. on the growth and fecundity of broodstock Xiphophorus helleri was evaluated. Weekly supplementation showed no measurable advantage over flake feed only. A direct correlation was demonstrated between fecundity and size of female fish when fed a formulated flake feed only. Fish fed a daily Daphnia supplement had a mean final weight of 5.97 g, feed conversion ratio of 1.33 and mean fecundity of 190 embryos per female, which was significantly higher than the yield from the non-supplemented or weekly supplemented treatments. Despite these differences, the number of young harvested during the experiment did not differ (P > 0.05) between treatments and this discrepancy was ascribed to parental cannibalism of new born juveniles. This revised version was published online in August 2006 with corrections to the Cover Date.     

The effect of stocking density and repeated handling on the growth of juvenile mulloway, Argyrosomus japonicus (Temminck & Schlegel 1843)

The effect of stocking density on the growth of mulloway, Argyrosomus japonicus, was tested with 17 g fish stocked at 4.08, 8.16, or 16.32 kg m⁻³ in 50 l aquaria. Weight checks were carried out every 2 weeks to track performance. Each density treatment was also compared to a nonhandled control group to establish if handling during weight checks influenced the growth of mulloway. Mulloway performed poorly at the lowest density and, under the current experiment conditions, growth did not appear to be negatively affected by regular handling.     

牙鲆基因组 (CAG)n微卫星 DNA 特征分析

通过磁珠富集法筛选牙鲆(Paralichthys olivaceus)的微卫星分子标记,采用限制性内切酶Sau 3A Ⅰ对牙鲆完整基因组DNA进行酶切;通过蔗糖溶液梯度离心,收集400～900 bp大小的片段,连接Brown接头,构建牙鲆基因组文库.用生物素标记的微卫星探针(CAG)15,对基因组文库进行杂交,利用磁珠富集含有微卫星的DNA单链序列,并对其进行PCR扩增;将扩增产物连接到pMD18-T载体后转入感受态大肠杆菌DH5α中,得到微卫星序列文库.利用大量质粒检测法进行二次筛选,成功地从牙鲆基因组中分离出含有CAG重复的微卫星序列,测序其中的3000个单菌落,获得2805个(占93.5%)含有微卫星序列的克隆,其中含有微卫星座位3120个,完美型1808个,占57.97%;非完美型226个,占7.25%;混合型1085个,占34.78%.从中选出186个微卫星序列设计120对引物并合成,经过筛选,74对引物可扩增清晰条带,其中68对呈多态性.     

Diversity in reproductive traits of arapaima (Arapaima spp., Müller, 1843) in Amazonian várzea floodplains: Conservation implications

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溴氰菊酯在欧洲鳗鲡体内药代动力学研究

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Diel changes in plasma cortisol and effects of size and stress duration on the cortisol response in European sea bass (Dicentrarchus labrax)

European sea bass (Dicentrarchus labrax), one of the most economically important fish in Mediterranean mariculture, shows high basal cortisol concentrations compared with other teleosts. The present study aims (a) to identify cortisol diel variation in fish held under a 12L:12D cycle and minimum handling stress, and (b) to establish the effect of fish size and stressor duration on the cortisol response. The results indicate high intrapopulation variability in plasma cortisol and a significant diel fluctuation with a peak value at dusk (18 h). Stressors of different intensity and/or duration affected the cortisol stress response in a differential manner according to fish size (and/or age). Maximum cortisol values in small-size fish were found at 1 and 2 h post-stress, depending on the duration of the stressor, while at 0.5 h post-stress in large fish regardless stress duration.