Some abundant Tendipedid species (Diptera, Tendipedidae) of the Amu-Darya drainage basin. Acalcarella shilova, gen.n. only [Translation from: Ent.Obozr. 34 313-322, 1955]

This document is a partial translation of taxonomic notes on two Diptera species (Acalcarella Shilova, Acalcarrella nucus) which were abundant in a survey of Tendipedid species (Diptera, Tendipedidae) of the Amu Darya drainage basin. These taxonomic notes of the larva, pupa and adults include drawings of the Acalcarella nucus larva.

An identification key of the most important German freshwater teleost fishes by means of their eggs [Translation from: Archiv fur Hydrobiologie 83(2), 200-212, 1978]

The fetal and larval development of many freshwater fish is already relatively well covered. Coverage of the morphology of fish-species' eggs is very sparse. For this reason the authors have attempted to prepare a key on fish eggs which covers the bulk of German Teleostei fish. The key also includes a discussion of problems of categorization and terminology.

Dangeardia sporapiculata n.sp., the term 'apiculus' and the species limitation of some chytrids [Translation from: Sydowia 16 324-330, 1963]

Taxonomic observations are given on Dangeardia sporapiculata n. sp. Furthermore the term 'apiculus' and the species limitation of some chytrids are being discussed. It is concluded that the newly described species Dangeardia sporapiculata does not fit satisfactorily into the present system of phlyctidiacee, because their characteristics do not agree exactly with any genus.

Provisional atlas of the freshwater leeches of the British Isles

Distribution maps were included in the second edition of the F.B.A. Scientific Publication on British freshwater leeches (Mann 1964). When that publication was extensively revised and enlarged to include a review of the literature on the ecology of leeches (Elliott & Mann 1979), it was decided that new maps should be published separately. The original maps were based on 1097 records whereas 4198 records were used for the new maps. The total British Isles list comprises sixteen species, thirteen genera and four families of leeches.

From the individual to the community and beyond: water quality, stress indicators and key species in coastal waters

This review examines water quality and stress indicators at levels of organisation from the individual to the community and beyond by means of three case studies concentrating on rocky shores within the north-east Atlantic. Responses of dogwhelks (Nucella) to tributyltin pollution from antifouling paints is examined as the main case study. There are effects at the individual level (development of male sexual characteristics in the female leading to effective sterility) and population level (reduction in juveniles, few females and eventual population disappearance of dogwhelks in badly contaminated areas) but information on community level effects of dogwhelk demise is sparse. Such effects were simulated by dogwhelk removal experiments on well studied, moderately exposed ledges on shores on the Isle of Man. The removal of dogwhelks reduced the size and longevity of newly established Fucus clumps that had escaped grazing. Removal of dogwhelks also increased the likelihood of algal escapes. In a factorial experiment dogwhelks were shown to be less important than limpets \{Patella) in structuring communities but still had a significant modifying effect by increasing the probability of algal escapes. Community level responses to stress on rocky shores are then explored by reference to catastrophic impacts such as oil spills, using the Torrey Canyon as a case study. Recovery of the system in response to this major perturbation took between 10-15 years through a series of damped oscillations. The final case study is that of indicators of ecosystem level change in response to climate fluctuations, using ratios of northern \{Semibalanus balanoides) and southern (Chthamalus spp.) barnacles. Indices derived from counts on the shore show good correlations with inshore sea-water temperatures after a 2-year lag phase. The use of barnacles to measure offshore changes is reviewed. The discussion considers the use of bioindicators at various levels of organisation.

The connection between single species and ecosystems

Ecosystem level models are motivated by some combination of scientific and practical concerns. Those models motivated by practical concerns are likely to bear little historical relation to previous models. Mechanisms of interaction between particular species and their ecosystems vary enormously. Some species literally construct their own ecosystems. Others have more or less complex and important interactions with other species so that their presence or absence may alter the ecosystem. Prior information about the natural history of particular species can make ecosystem investigations quicker, cheaper, and more effective. The optimal resource for preparing to deal with the unlimited diversity of questions asked of ecologists would be a large' computerized databank of natural history observations for as many species as possible.

Aspects of the biology and population dynamics of freshwater mussels in Lake Kariba and Lake McIlwaine

The essential aim of this study was to provide a broad foundation of biological knowledge upon which a programme of mussel utilization and management could be built. Results of the study are presented in three main sections. Part 1 describes the stock of Lake Kariba and Lake McIlwaine; part 2 describes various aspects of the breeding biology of the three species; and part 3 presents the results of morphological, biochemical and age analyses - aspects which are used for initial standing crop and production calculations. The final discussion concludes the thesis with a general examination in ecological terms of the factors which have influenced the development and nature of the mussel faunas of the two lakes under consideration.

FishBase species profile: Clarias gariepinus (Burchell, 1822) North African catfish

In this issue NAGA introduces a new page on profiles of fish species. This page will be a permanent feature of the NAGA and will be based on information derived from FishBase (http://www.fishbase.org), the world’s premier information system on fishes and a global public good. FishBase is being developed by the WorldFish Center and an International Consortium. The first species selected is the North African catfish Clarias gariepinus, one of the most important freshwater fish species in Africa. It has been chosen in honor of Prof Dr Guy Teugels of the Musée Royal de l’Afrique Centrale (MRAC) of Tervuren, Belgium, who recently passed away and who spent many years investigating this species.

An annotated checklist of freshwater fishes of Armenia

A list of freshwater fishes inhabiting lakes, reservoirs and rivers of Armenia is presented which include 39 species and subspecies belonging to 5 orders, 9 families and 29 genera. A brief description of the ecology, distribution and present status (introductions, threats, commercial value) of these fishes is given.

Freshwater pearl culture in India

Freshwater pearl culture is growing as a source of employment and income in many Southeast Asian countries. Bangladesh, Thailand, the Philippines and Vietnam have initiated freshwater pearl culture projects in recent years. In India, the Central Institute of Freshwater Aquaculture is carrying out research on identification of suitable local pearl mussel species (Genera Lamellidens)defining appropriate surgical implantation procedures, developing post-operative care procedures and captive pond culture of mussels.

Length weight relationships of Nigerian freshwater fishes

Length-weight relationships of 73 fish populations, covering 20 families, 28 genera and 40 species inhabiting freshwater ecosystems in Nigeria, were estimated (73 cases) or assembled from the literature (20 cases), and tested for difference between ecosystem types, There were no significant differences in the exponent of these relationships between lotic and lentic systems.

Length-weight relationships of freshwater fishes in Greece

Length-weight relationships were calculated for nine fish species from Lake Volvi (Macedonia, Hellas), caught with gillnets of five different mesh sizes between October 1995 and October 1996. In addition, length-weight relationships for 24 Greek freshwater fish species and one hybrid were also obtained from the literature. The values of the exponent of the length-weight relationships for all fish species examined ranged between 2.14 and 3.70 (mean = 3.12; SE=0.0321), and the median value was 3.19.

Genetic diversity in wild stocks of the giant freshwater prawn (Macrobrachium rosenbergii): implications for aquaculture and conservation

The giant freshwater prawn (Macrobrachium rosenbergii) is cultured widely around the world but little is known about the levels and patterns of genetic diversity in either wild or cultured stocks. Studies have suggested that genetic diversity may be relatively low in some cultured stocks due to the history of how they were founded and subsequent exposure to repeated population bottlenecks in hatcheries. In contrast, wild stocks have an extensive distribution that extends from Southern Asia across Southeast (SE) Asia to the Pacific region. Therefore, wild stocks could be an important resource for genetic improvement of culture stocks in the future. Understanding the extent and patterns of genetic diversity in wild giant freshwater prawn stocks will assist decisions about the direction future breeding programs may take. Wild stock genetic diversity was examined using a 472 base-pair segment of the 16S rRNA gene in 18 wild populations collected from across the natural range of the species. Two major clades ("eastern" and "western") were identifi ed either side of Huxley’s line, with a minimum divergence of 6.2 per cent, which implies separation since the Miocene period (5-10 MYA). While divergence estimates within major clades was small (maximum 0.9 per cent), evidence was also found for population structuring at a lower spatial scale. This will be examined more intensively with a faster evolving mtDNA gene in the future.

Freshwater prawn farming trials in Bangladesh

Details are given of pond trials conducted in Bangladesh regarding the culture of freshwater prawn (Macrobrachium rosenbergii ). Integrated rice and prawn farming systems were also experimented and results indicated that the prawn could be a suitable species for such integration. Such systems, pond or integrated, are suggested to be best practiced in the southeastern and southwestern areas of the country where there is tidal water exchange and post-larvae are naturally available.

Stocking, Enhancement, and Mariculture of Penaeus orientalis and Other Species in Shanghai and Zhejiang Provinces, China

China's marine aquaculture landings provide only 18% of its combined freshwater and amrine capture and culture landings, at a per-capita consumption of only 3.2 kg/yr out of a total of 18.1 kg/yr. We described development and some of the results of long-term mariculture and stocking/enhancement projects that have been underway for up to 20 years in the Hangzhou Bay area. Penaeus orientalis (also referred to as P. chinensis) stocking provided up to 400 t/yr, at a total cost-benefit ratio of up to 8 Yuan of landed shrimp per Yuan invested in shrimp stocking. Over 40 t of Penaeus orientalis were produced commercially in 1993, with proceeds being used to fund mariculture and fisheries research. Large scale edible jellyfish restocking is also underway, while semicommercial culture of abalone, Haliotis diversicolor, has been successful. Technical problems limitig mariculture have been solved successfully for some species.