Studies on distribution, diversity and production of macrobenthic fauna in the Chahbahar Bay

The population density, distribution, diversity and secondry production of macrobenthic fauna of the inner Chahbahar Bay were studied through bi-monthly sampling from April 1995 to March 1996. Samples were collected from water near the bottom and sediment at 14 stations inside the Bay and one reference station located outside at the entrance to the Bay. The environmental parameters Such as temperature, water depth, salinity, pH and dissolved oxygen as well as percentage silt-clay and total organic matter of the sediment were measured. The faunal population density and their distribution is discussed in relation to the environmental changes. results obtained indicated both spatial and temporal heterogeneity in faunal distribution of the Chahbahar Bay. The total of 18 groups of macrofauna were identified in all samples. Amphipods formed the dominant group (21%) followed by polychaetes (19%), gastropods (15.7%) bivalves (10.6%) and all other groups (33.7%). Seasonal changes in faunal density is shown in relation to Indian Ocean southwest monsoon,the result of which indicated lower population density during monsoon (June to September) than that of the premonsoon (February to May) and post monsoon (October to January) periods. The numerical abundance of macrobenthos varied from 10260.m2 before monsoon to 5190 m2 during monsoon season. Three dominant groups of macrofauna including polychaetes, gastropods, and bivalves were identified in all collected samples. Indices of diversity, richness and evenness were calculated for these three dominant groups. The Shannon-Weaver information index was used to describe the spatially and temporally variation in diversity of these three major faunal groups. The results exhibited lower faunal diversity during monsoon period. The annual production of two dominant macrofauna species including a species of bivalve, Nuculana acuta and a species of Cephalochordata, Branchiostoma lanceolatum were measured by using age group determination. Furthermore the mean biomass and total annual production of macrobenthic fauna were estimated for the whole studied area. The potential yield of demersal fishery resources (fish and crustacean) then estimated and worked out to be 15360 tons/year asuming 10% ecological efficiency of hypothetical pyramid from 3rd to 4th marine trophic level. Accordingly the annual exploitable demersal fishery resources for the entire Chahbahar Bay was estimated to be 7600 to 8500 tons/year by taking 50 to 55% of the total estimated potential in to account.

Nutritive value of fish of Lake Tanganyika [part] I: Amino acid composition

The amino acid composition was determined of three economic important fish species of Lake Tanganyika, representing 95% of the tolal catch:Stolothrissa tanganicae Regan, Limnothrissa miodon Boulenger and Luciolates stapersii Boulenger. The analysis of the whole sun dried fish indicate that, compared with Tilapia macrochir, beef and the whole hen's egg, the fish is of a very high nutritive value. The free amino acids in the dried fish count for an average of 11 %, indicating the degree of auteolysis.

The future prospects of the fish stocks of Lake Victoria, Uganda

Experimental trawling during the period 1981/86 and analysis of past commercial catch landings, mainly in the northern portion of Lake Victoria have indicated that the standing stocks and therefore, the estimates of sustainable yields of the most important fish species have unquestionably changed since the 1969/71 comprehensive lake-wide stock assessment survey. Lake Victoria which was originally a multi-species fishery now relies on two introduced species (Lates niloticus and Oreochromis niloticus) and one indigenous cyprinid (Rastrineobola argentea). Most of the traditional fish species, including the once dominant haplochromines, have either declined or disappeared. The catch rates in the experimental trawl catches declined from 797 kg/hr in 1969/71 to 575 kg/hr in 1981 and 166 kg/hr in 1985. The contribution of L. niloticus in the trawl catch increased from 0.9% in 1981 to 95.6% in 1985 while the contribution of the haplochromines decreased from about 91% to about 1% over the same period. The mean size of the individual fish caught (particularly the Nile perch) was also on the decline. Similar trends were also observed in the commercial fishery. However, recent observations in the Lake Kyoga commercial fishery that O. niloticus has now surpassed L.niloticus in importance may create more uncertainty regarding the future trends of the fish stocks of Lake Victoria. Inspite of the above situation, developments to increasingly exploit the fish stocks of the lake for export continue to take place. A number of fish processing and/or handling plants have been established in the Jinja, Kampala and Entebbe areas of the lake. Each of these plants is capable of handling upwards of 10 tons of fish a day, the target fish being L. niloticus and O. niloticus.

A key to the families and genera of freshwater fishes of Tanzania

The purpose of this key is to facilitate rapid and accurate identification, in the field, for fisheries workers. It is therefore based as much as possible on external characters only and an attempt has been made to keep it simple and straight forward. The only real difficulty arises in clearly demarcating the numerous cichlid genera of the great lakes, despite the fact that these have been treated in separate sections for each lake. Moreover, it hasn't been possible to revise the key to the lake Nyasa genera (taken from Jackson, 1961) to any significant extent, my experience with L. Nyasa fishes being limited; also, a few new genera have been or are still in the process of being published and I unfortunately haven't had access to these papers. A short bibliography is appended covering the major publications relevant to the systematics of Tanzania freshwater fishes and the sources from which these keys have been drawn up.

Past and present limnological investigations in Uganda: an overview

The limnological investigations in Uganda freshwaters which were started in the 1920s looked into: the origins, the changing geological and climatic factors which gave rise to the characteristic inland waters; the primary production; the constituent small aquatic organisms and their ecology; and their bordering swamps. Most of them were formed immediately after the formation of the great Western rift valley. Almost all the inland waters in Uganda are typical tropical freshwaters which, because of their relative shallowness, experience rather frequent wind stirrings and therefore nutrient circulation which would make them relatively productive. Many physical, biological and chemical factors come into play to finally determine this. The present investigations continue to bridge the gaps which were left and also to collect the baseline data needed to later manage, monitor and control any possible pollution risks.

臭蛙群三种蛙类核型及染色体带型的比较(英文)

本文比较了3种臭蛙,即云南臭蛙（R. andersonii）、无指盘臭蛙（R.grahami）和滇南臭蛙（R.tiennanensis）的核型、C-带和银染核仁组织者区（Ag-NORs）。结果表明,3种臭蛙的核型均为2n=26（NF=52）,由5对大型染色体和8对小型染色体组成,与蛙科大多数种类的核型相似,但是染色体形态和次缢痕的位置和数目有差异。其中,云南臭蛙和无指盘臭蛙的核型相似程度比较大,与其他已报道的臭蛙类的核型相差不大,而滇南臭蛙的核型比较特殊,与其他臭蛙类的核型存在显著差异。 C-带技术显示的结果表明,3种臭蛙所有染色体的着丝点都有比较显著的C-带,而居间区C-带和端点C-带却存在明显的差异。3种中,滇南臭蛙的C-带带型比较特殊。有趣的是在研究中还发现,云南臭蛙的早中期细胞（染色体很长）染色体上发现了很多结构异染色质区,除着丝点C-带外,几乎所有的染色体上都有居间区或端点C-带,而在晚中期细胞中所观察到的C-带数目却较少,除着丝点外,只在少数染色体上发现了C-带。 云南臭蛙和无指盘臭蛙的Ag-NORs位于第10对染色体的长臂上,与该染色体上的次缢痕位置相对应,而滇南臭蛙的Ag-NORs位于第6...

川金丝猴(Rhinopithecus roxellanae)月经周期促黄体素(LH)的分泌水平

用改进的LH体外生物测定法, 测定了川金丝猴两个月经周期的晨尿LH含量。结果表明LH峰分别出现在各月经周期的第16天和11天。LH峰的平均水平为100.0±9.0miu/ml尿[以人促黄激素(hLH)69/104作为标准], 是滤泡期LH平均水平的6倍, 黄体期LH平均水平的4倍。川金丝猴月经周期LH的分泌情况与人和猕猴的极为相似。表1图3

短尾猴下颌骨的性二型

短尾猴下颌骨性二型的判别式为:D=-11.013+1.151下颌骨髁长+0.269下颌骨髁宽。当D=-1.271±0.182时,标本为雌性;当D=0.973±0.290时为雄性。短尾猴下颌骨髁的长和宽, 可作为种内性别间的鉴别特征。图2表2参21

Recent advance in the study of ribosomal model.

With the technological developments of cryoelectron microscope, X-ray diffraction and the growing data available on various components of ribosome, some marvelously intricate structural models of the Escherichia coli 70S ribosome have been reconstructed. The picture of the ribosomal model are detailed, including the placement of the mRNA, the arrangement of the A-site and P-site tRNAs and the peptidyltransferase within the interface gap as well as the path of nascent polypeptide chain, which results in a better understanding of the structure and function of ribosome as well as the translational process.