云南洞穴金线鲃属鱼类(鲤科)一新种   总被引：1，自引：0，他引：1  

卯卫宁  卢宗民  李维贤  马鸿宾  黄钢 《广东海洋大学学报》2003,23(3):1-3

描记采于罗平县—地下河金线鲃属一新种,命名为瓦状角金线鲃Sinocyclocheilus tileihornesMao,Lu et Li,sp.nov。新种外形与犀角金线鲃S.rhinocerous Li et Tao(1994)相近,但新种无侧线鳞,角顶部分叉呈瓦状,腹鳍较长,后伸超过肛门或达到臀鳍起点可与之相区分。  相似文献   

Phytoplankton,especially diatoms,in the gut contents and feces of two plantivorous cyprinids—Silver carp and bighead carp     

Xie Ping  Liu Jiankang 《中国海洋湖沼学报》1994,12(4):308-315

In order to clarify whether the planktivorous silver carp and bighead carp can collect phytoplankton as small asCyclotella(<20 μm) in Donghu Lake, studies on phytoplankton in their gut contents and feces were made in 1990. The fish were cultured in both net cage in Donghu Lake and aquaria with the lake water. Past the intestine, the average valve diameter ofCyclotella changed little. The average ratio of empty frustule ofCyclotella to totalCyclotella in the foregut contents of the fishes were 1.8–1.9 times higher than that in the lake water, but changed little from foregut to feces. The aquarium experiment showed that both carps could collect particles as small as 8–10 μm, which was obviously narrower than the distance between their gill rakers. Probably, secretion of mucus plays an important role in collecting such small particles.  相似文献   

Proximate composition of albacore tuna,Thunnus alalunga,from the temperate South Pacific and Tasman Sea     

Peter Vlieg  Talbot Murray 《新西兰海洋与淡水研究杂志》2013,47(4):491-496

The proximate composition was determined of the white muscle of albacore tuna, Thunnus alalunga, caught by surface trolling along the Subtropical Convergence Zone east of the South Island of New Zealand ("Area 1"), and to the north and west of the North Island ("Area 2"). Fish from Area 1 were 70 ± 10 cm (mean ± s.d.) in fork length, and higher in oil content (4.6 ± 2.9%), than Area 2 fish which measured 55 ± 10 cm and contained 2.8 ±1.7% oil. The ash content of the white muscle of all fish sampled was 1.2 ± 0.1%, and the soluble carbohydrate content 0.36 ± 0.04%. Crude protein contents were calculated at c. 25%. Statistical relationships between moisture and oil contents of both white and red muscle were determined; they can be used to predict oil content from a known moisture content. Oil content was positively correlated with fork length, and negatively correlated with the sea surface temperature at time of capture. Oil levels in the fillet were highest in the muscle layer immediately below the skin and decreased logarithmically with depth. In fish with low white‐muscle oil content (below 5%), the corresponding red‐muscle oil content was higher; above 6% white muscle oil content the corresponding red‐muscle oil content was lower. The proximate composition of whole fish, the head, frame, skin, and viscera is presented.  相似文献   

Early oligocene squalodont cetacean from Oamaru,New Zealand     

I. W. Keyes 《新西兰海洋与淡水研究杂志》2013,47(4):381-390

Records of Tertiary fossil cetacea from New Zealand are revised. Probable proto‐squalodontid teeth from the McDonald Limestone Formation (Whaingaroan Stage, Lower Oligocene), Oamaru, are described, and represent the oldest cetacean remains found in New Zealand. This record demonstrates the probable extension of the Squalodontidae into the Lower Oligocene.  相似文献   

中国草食家畜养殖的时空动态及其影响因素   总被引：1，自引：0，他引：1  

王国刚  王明利  王济民  杨春  刘玉凤 《地理学报》2015,70(7):1091-1100

发展草食家畜养殖是推动中国耗粮型畜牧业向节粮型畜牧业转型、解决人畜争粮矛盾的关键。本文运用探索性空间数据分析技术和计量模型方法,系统考察了中国草食家畜养殖的时序变化过程、地理集聚特征及其影响因素。研究表明：① 中国草食家畜养殖量整体增长态势明显,但畜种间养殖量存在较显著的差异。1978-2012年中国草食家畜养殖量增长了92.5%;同期养殖量肉牛>肉羊>奶牛。② 县域尺度上,草食家畜养殖量增长区数量多于减少区,而且北方地区养殖量增长明显快于南方地区,初步形成了“北热南冷”的空间格局。③ 空间杜宾模型显示,人均粮食产量、生产性土地面积比重、城镇人均可支配收入、农业机械化水平、农业劳动生产率与政策因素五项指标,对草食家畜养殖的发展有着正向效应,而人均GDP、城镇化水平和非农收入比重有着显著的负向效应。④ 中国草食家畜养殖可划分为6大类型区,各类型区应根据“区情、农情”从不同的侧重点加以调控。此外,还应优化调整区域种养结构、实行差别化的区域发展对策及重视养殖集聚区非农产业发展,稳定、促进草食家畜养殖业的发展。  相似文献   

Der Einfluß des Bibers (Castor fiber albicus) auf die Fauna (Odonata, Mollusca, Trichoptera, Ephemeroptera, Diptera) von Mittelgebirgsbächen in Hessen (Deutschland)     

Mark Harthun 《Limnologica》1999,29(4):449-464

Due to the return of the beaver an increasing number of brooks become restored to a natural condition. It is characterized by an alternation of flowing and standing sectors. In the summer of 1995, different groups of organisms (Odonata, Mollusca, Trichoptera, Ephemeroptera, Diptera) of two brooks in the Spessart mountains (Hesse, Germany) were studied to compare the composition of invertebrates in beaver homeranges and in the non-influenced sectors above. The new living conditions resulted in the disappearance of some species (Drusus anulatus, Trich., Sericostoma personatum, Trich., Radix peregra, Gastr.). Nevertheless the beaver homeranges accommodate a significant higher number of species of dragon flies and damsel flies, molluscs and caddis flies than the brooks above the homeranges. The heterogeneity of natural river systems make a coexistence of running water and silent water organisms possible. The examinations result in a significant higher group dominance of ephemeras (i.p. Cloeon dipterum) in a beaver pond than in lenitic sectors conditioned by the gradient without beaver influence. Here the dominance of chironomids was much higher. High current sectors with their characteristic organisms are also present in the beaver homeranges. The higher number of insects is the basis of nourishment for predatory insects and fishes. The potential effects of beaver ponds on fishes are discussed.  相似文献   

Consequences of artificially opening coastal lagoons on their fish assemblages     

Shane Paul Griffiths 《International Journal of Salt Lake Research》1999,8(4):307-327

The consequences of artificially opening lagoon entrances on the fish assemblages of coastal lagoons in south-eastern Australia were investigated. Impacts of lagoon opening were assessed by comparing changes in the fish assemblages of Werri and Shellharbour Lagoons, both of which intermittently opened to the sea with that of Lake Illawarra, a third coastal lagoon which remained closed during the study period. Numbers of fish species and individuals did not differ significantly after lagoon openings at Werri Lagoon and Shellharbour Lagoon. However, higher numbers of species and individuals were found in Lake Illawarra before the other lagoons had opened. Abundances of some economically significant species (namelyMugil cephalus, Myxus elongatus andLiza argentea) significantly increased after openings, mainly due to small juveniles (<40 mm FL) recruiting to the seagrass beds. In contrast, these species were caught as larger juveniles (>70 mm FL) in Lake Illawarra. Furthermore, their abundance in Lake Illawarra declined during successive months, coinciding with declining salinity. Abundances of resident species (such asPseudomugil olorum andAfurcagobius tamarensis) remained largely unchanged after openings. Although it was clear that marine-spawning species must benefit from lagoon openings, the number and composition of species able to move into lagoons from adjacent waters may be dependent upon the frequency, duration and time of year that the entrance is connected to the sea. The present study thus provides data which may be useful for fisheries management in intermittently open lagoons. However, these results should not be cited as reason to artificially open lagoon entrances as further detailed studies of other aspects of lagoon biota, such as their invertebrate and avian faunas, are also needed to provide sufficient basis for broader management frameworks.  相似文献   

有毒铜绿微囊藻对鱼和溞的毒性   总被引：7，自引：0，他引：7  

何家菀  何振荣  郭琼林 《湖泊科学》1997,9(1):49-56

用有毒铜绿微囊藻细胞及其从毒细胞中提取的毒素喂养和腹腔注射鱼类,结果表明:(1)微囊藻毒素MCYST-LR对所有实验过的鱼有毒害作用(LD₅₀为110-500μg/kg).注射毒素24h后,鱼肝电镜超微结构观察均表现出肝损伤.(2)在受控条件下,当用有毒铜绿微囊藻作为食物喂养日鲢和罗非鱼时,鱼类能在以毒藻为唯一食物的环境中生活20d以上.白鲢和罗非鱼粪便的毒性比喂食藻类的毒性分别降低约2-4.5倍,其肝的超微结构现察仍有轻度损伤.(3)在培养液中加入15μg/mLMCYST-LR和用实验室纯培养的铜绿微囊藻作为食物培养枝角类时,均可使它们在48h死亡.以无毒微囊藻培养时则生长不良亦不怀卵,表明它不是枝角类合适的食物.  相似文献   

Diel Changes in Assemblages of Fishes Associated with Shallow Seagrass and Bare Sand     

C.A. Gray  R.C. Chick  D.J. McElligott 《Estuarine, Coastal and Shelf Science》1998,46(6):849-859

The evaluation and management of fisheries resources requires knowledge of spatial and temporal changes in the habitat-associations of fishes. However, most studies concerning habitat associations of small fishes in the shallow regions of estuaries have been limited to daytime sampling strategies. Diel changes were investigated in assemblages of fishes associated with shallow seagrass (Zostera capricorni) and bare sand in two estuaries in south-eastern Australia. Habitat-related differences in assemblages were strong day and night, and were greater than diel changes in assemblages. The seagrass-associated assemblages remained similar day and night and consistently differed from those associated with bare sand. In contrast, the assemblages over sand varied on a diel basis as larger individuals of several species (e.g.Gerres subfasciatus,Platycephalus fuscus) that resided over other (deeper) habitats during the day were caught over shallow sand at night. Further, some species (e.g.Ambassis jacksoniensis) that resided in seagrass during the day occurred over sand at night. Both habitats were utilized by newly recruited juveniles of economically important species and the habitat-associations of these species generally did not differ on a diel basis. Therefore, both habitats are considered important to the fisheries resources of south-eastern Australia. Inclusion of night-time sampling provided a greater understanding and appreciation of the use of the unvegetated habitat by fishes than has previously been acknowledged from studies based solely on daytime sampling. This study indicates that greater consideration of temporal changes in habitat associations of fishes is required in other geographic regions.  相似文献   

东海中部夏季鱼类群落结构及其多样性分析   总被引：2，自引：0，他引：2  

林楠  苗振清  卢占晖 《广东海洋大学学报》2009,29(3):42-47

根据2008年8月东海区主要渔场重要渔业资源调查资料,分析东海中部鱼类的种类组成、区系特征、多样性等群落结构特征。结果表明:共调查捕获鱼类88种,其中暖水种59种,占67.0%;暖温种29种,占33.0%。相对重要性指数(IRI)值大于500的优势种鱼类共有5种,分别为带鱼、刺鲳、小黄鱼、六斑刺鲀和鳄齿鱼;种类丰富度指数变动范围为0.10～2.31,平均为0.88;Shannon-Wiener多样度指数变动范围为0.01～1.86,平均为0.87;种类均匀度指数变动范围为0.01～0.92,平均为0.41;东海中部夏季鱼类多样性指数与往年相比有下降的趋势。  相似文献