978 resultados para 312.282
Resumo:
1992年12月,1993年11月及1994年4-5月,对西双版纳自然保护区内外的数个工作点进行了鸟类物种多样性的调查,共记录鸟类190种。分析表明雀形目鸟类物种多样性状态尚佳,而非雀形目鸟类类群(科种)多样性及物种多样性状态均有恶化趋势。保护区内鸟类物种多样性状态明显较好。傣族墓葬地之龙山因依傍村落、农田及其地多种生境而具有相当丰富的鸟类物种多样性,是保护鸟类物种多样性不可忽视的一个方面。
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Source of the Nile Fish farm (SON) is located at Bugungu area in Napoleon Gulf, northern Lake Victoria. The proprietors of the farm requested for technical assistance of NaFIRRI to undertake regular environment monitoring of the cage site as is mandatory under the NEMA conditions. As the SON is a key collaborator/client of the institute, NAFIRRI agreed to undertake the assignment subject to facilitation by the client. The institute agreed to conduct quarterly surveys of key environmental parameters at the site including selected physical-chemical and biological factors, nutrient status, column depth, water transparency and sedimentation. Samples and field measurements were to be taken at 3 sites: within and/or close to the fish cages (WIC), upstream (USC) and downstream (DSC) of the cages. The first environmental monitoring survey was undertaken in February 2011; the second in May 2011 and the third in September 2011. The surveys cover physical-chemical parameters, nutrient status, invertebrate and fish communities. The present report presents field observations made for the fourth quarter survey undertaken in November 2011 and provides a scientific interpretation and discussion of the results with reference to possible impacts of the cage facilities to the water environment and the different aquatic biota at and around the cage site including natural fish communities.
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先用甲醇固定, 再用稀盐酸抽提方法对嗜酸热硫球菌染色质碱性蛋白进行了提取, 并将它与小牛胸腺组蛋白进行了比较研究。所获蛋白在两种电泳系统中都显示三种主要成分, 其分子量均小于小牛胸腺组蛋白H4。三者中以分子量最大者含量最高, 碱性则以分子量最小者最强。图2参12
Resumo:
下载PDF阅读器发光生物因其活体能自发荧光而倍受关注,萤火虫(鞘翅目:萤科)是被研究最多的发光生物,因为成虫发光在其性选择以及求偶交配中起着重要作用.由于萤火虫的发光是一个消耗能量(ATP),的化学反应过程,因而其发光在成虫之外的虫态也具有重要意义.本文就萤火虫成虫和幼虫的发光行为、功能意义进行了综述,并结合萤火虫的饲养观察对其卵和蛹的发光行为进行了描述,探讨了卵和蛹的形态阶段发光的生物学功能以及生物荧光的起源进化.这将有助于理解萤火虫及其它生物自发荧光的本质和起源进化过程.
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藏猴手足面上皮纹与其他猕猴属动物基本相同;其指趾端上的花纹几乎全是原始花纹;掌面上,大小鱼际主要为箕形和开放形花纹,指间Ⅰ-Ⅳ区主要为斗形纹;跖面上,大小鱼纹及趾间Ⅰ-Ⅱ区则主要是箕形纹,趾间Ⅲ-Ⅳ区主要是斗形纹。左右端指间Ⅱ-Ⅳ区及趾间Ⅲ-Ⅳ区花纹分布有一定差异。性别之间在指间Ⅰ区有显著差异。四川峨眉山及凉山雷波县两地猴则在掌面大鱼际、指及趾间Ⅰ区具显著差异,可能与地理和社会隔离相关,趾间Ⅳ区的特征性Da花纹及弓形纹缺失似可作为藏猴皮纹的一个特征。
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Class Condrichthyes consist of two sub-classes: Holocehali and. Elasmobranchii, the second one are more divers and has more importance. Selachimorpha (sharkes) and Batidoidimorpha (rays and skates) are two super-order of Elasmobranchii, which they have crucial role in ecological balance in marine ecosystmes. Except few cases, most of sharks and rays (rays and skates) are not well identified, so a lot of works need to be done in this regards. The area of study is located between 49°, 35' and 52°, 33' E and between 27°, 21' and 30°, 02' N in depth of 7 to 78 in. Study were conducted diuring August 1998, September 1999. Samples were taken during 3 sea cruises from 70 bottom trawl net. All sharks and batoid fishes were identified based on biometric specifications (weight, total, length and sexuality for both group and extra biometric specifications, disc width, disc length, and tail length only for, batoid fishes). The 1140 specimens of batoid fishes identified belonged to 6 families, and 18 species. 3 new species were identified, they are Himantura sp.1 and Himantura sp.2 belonged to Dasyatidae family and Rhinobatos sp. belonged to Rhinobatidae Familiy. It needs more works and more adaquate ducuments for cl.earfing scientific names of these species. The 275 specimens of sharks identified belonged to 6 families and 10 species. Chiloscyllium sp. belonged to Hemiscylliidae, family as a new species was identified.
Resumo:
Rastrineobola argentea, local name.s Mukene (Uganda) Omena (Kenya) and Dagaa (Tanzania) occurs in lakes Victoria, Kyoga and Nabugabo (Greenwood 1966). Until the decline of the native fishes especially the haplochromines, R. argentea was of little economic importance to the fisheries of these lakes. The stocks of this species have now increased and commercial catches on Lake Victoria account for over 30%. Fishing for R. argentea is currently still restricted to inshore areas and within the fringing islands of Lake Victoria. This fishery is not yet established on Lakes Kyoga and Nabugabo although the species is quite abundant in these lakes (Proude 1963). On moonless nights, kerosene pressure lamps are exposed on the lake to attract the fishes. These fishes are then fished out using fine meshed seine, lampara or lift nets
Resumo:
Prior to introduction of non-native fish species into Lakes Victor i a, Kyoga and Nabugabo, the three lakes suppor ted diverse fish fauna representing 13 families consisting of six cichlid genera and fifteen non-cichlid genera. There were about 50 non-cichlid species and over 300 cichlids consisting of mainly haplochromines (Graham 1929, worthington 1929, Greenwood 1960). Many of the species were commercially and scientifically important and provided a rich variety of protein source to choose from. Following introduction of the Nile perch and several tilapiines species, most of the native species were drastically reduced and some have apparently disappeared. The few remaining species appear to be restricted in distribution due to the presence of the Nile perch. They are mainly confined to refugia such as marginal macrophytes, rocky outcrops and small satellite lakes which are separated from the areas of introduction by swamps
Resumo:
Oreochromis niloticus (the Nile tilapia) and three other ti1apine species: Oreochromis leucostictus, Tilapia zi11ii and T. rendallii were introduced into Lakes Victoria, Kyoga and Nabugabo in 1950s and 1960s. The source and foci of the stockings are given by Welcomme (1966) but the origin of the stocked species was Lake Albert. The Nile tilapia was introduced as a management measure to relieve fishing pressure on the endemic tiapiines and, since it grows to a bigger size, to encourage a return to the use of larger mesh gill nets. Ti1apia zillii was introduced to fill a vacant ,niche of macrophytes which could not be utilised' by the other tilapiines. Tilapia rendallii, and possibly T. leucosticutus could been introduced into these lakes accidently as a consquence of one of the species being tried out for aquaculture. The Nile perch and Nile tilapia have since fully established themselves and presently dominate the commercial fisheries of Lakes Victoria and Kyoga. The original fisheries based on the endemic tilapiines O. escu1entus and o. variabilis have collapsed. It is hypothesized that the ecological and limnological changes that are observed in Lakes Victoria and Kyoga are due to a truncation of the original food webs of the two lakes. Under the changed conditions, O. niloticus to be either playing a stabilizing role or fuelling nutrient turnover in the lakes. Other testable hypotheses point to the possible role of predation by the Nile perch, change in regional climate and hydrology in the lake basins.
Resumo:
Haplochrmine cichlids were the most abundant taxa in Lakes Victoria, Kyoga and Nabugabo prior to introduction of the Nile perch. As stocks of the introduced predator increased, these taxa were depleted to such an extent that they are now virtually absent from the lake. The haplochromine cichlids played an important role in the ecology of Lakes Victoria, Kyoga and Nabugabo. They occupied virtually all trophic levels in the lake and facilitated an efficient flow of energy through the ecosystem. Their depletion seem to have left much organic matter whose decomposition has contributed to accumulation of dead organic matter which may be contributing to prolonged anoxia in Lake Victoria. The haplochromines formed an important small-scale fishery. Fishermen formerly subsisting on this fishery have been driven out of business because they cannot afford the expensive nets required for Nile perch fishery. In addition to providing a cheap source of fish protein to humans, the species were an important source of Scientific material for students of genetics antd adaptive radiation.
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A baseline survey for the project which had been conducted in 2009 had gaps that could not allow assessment of project performance in the outcome and impact indicators to be made. This study was, therefore, commissioned to reconstruct the baseline data, aligned to the impact and outcome indicators on the project logframe and results framework, against which project achievements could be assessed. The purpose and scope of the study was to reconstruct the baseline data and analysis describing the situation prior to QAFM Project inception, taking 2008 as the baseline year, which was aligned to the project logframe outcome and impact indicators; to collect data on current status to compare project outcome (and where possible impact) in improved fish handling sites in comparison with the baseline as well as with comparable non-improved fish landing sites as control group. The study was conducted through secondary data search from sources at NaFIRRI, DFR and ICEIDA. Field data collection was carried out using a sample survey covering 312 respondents including boat and gear owners, crew members, processors and traders at eight project and two control landing sites. Key Informant Interviews were conducted with DFOs and BMU leaders in the study districts and landing sites respectively.