Sri Lanka: is it a mid-plate platelet?

Two observations suggest the possibility that Sri Lanka is acting as a small-mid-plate platelet moving very slowly within and relative to the larger Indian plate. First, sediments of the Bengal Deep-Sea Fan off the SSE continental margin are folded and uplifted in a manner similar to the deformation from front of accretionary prisms where thick sediment columns are passing into subduction zones. And second, subsidence rates in the area of presumed spreading or continuing stretching of continental crust, the Cauvery-Palk Strait-Gulf of Mannar Basin, have not decreased during the Cenozoic as would be predicted by an aborted rift or aulacogen model, but instead appear to have accelerated during the Neogene. Information available on other phenomena which re predicted by the model is at the present time inadequate for evaluation.

Reservoir fishery resources of south-east Asia

Although the reservoir area in south-east Asia is considerable, the fish production is low in the majority of reservoirs. Although high fish production has been recorded in a number of reservoirs in Sri Lanka and Indonesia, high fish production in reservoirs has with few exceptions resulted from the introduction of typical lake species from Africa. Addition of further lake fish species especially into deeper reservoirs will probably increase present fish yields. Diversification of the lake fish fauna can be achieved by introduction of species indigenous to the region like Etroplus suratensis. In this introduction of fish species, three points may be noted with specific reference to Tilapia spp.: (a) Lakes without indigenous cyprinids show marked fluctuation in fish catch with the introduction of Tilapia, and this could be stabilised by the introduction of predators and more diverse species. (b) Lakes with a moderate diversity of fish fauna show a high stabilised production with the introduction of Tilapia, presumably because of the effect of predator pressure on excessive Tilapia breeding. (c) Lowland lakes with a rich diversity of indigenous fish species colonising lakes may not require the introduction of Tilapia. Introduction of invertebrates into reservoirs in south east-Asia has not been done deliberately so far. However, the experience in other parts of the world, notably the Soviet Union, indicates that such introductions are likely to prove beneficial and to increase fish production. The potential for a considerable increase in fish production from reservoirs exists in south-east Asia. Proper management is likely to cost less than what is required for fish culture. Rural areas are likely to benefit most from increased fish production in reservoirs, and this might be a way to provide cheap protein where it is most urgently needed.

Notes on the fish resources of the Bahuda estuary, Orissa, India

Estuaries form an important site for the zoologist as these are the places known to be very rich in food and nutrients and so, become nesting-cum-breeding grounds for many species and also, own good species diversity. Bahuda estuary of Orissa is located at the inter-state border of Orissa and Andhra Pradesh. Explored for many invertebrates, this estuary was not properly investigated for its rich fish fauna. Various surveys at Bahuda estuary revealed that it is an important site of study for the faunal diversity of fishes in the east coast. Forty-eight species belonging to 33 genera under eight orders and 22 families were examined referring standard literature· and methods. Most of the groups of fishes encountered are of commercial importance.

The fisheries resources of Lake Nakivali: report of a rapid assessment of the Lake Nakivali fishery

Lake Nakivali is one of the four small lakes that form what is known as the Koki lakes system. It is 14 km long, 6 km wide, 26 km2 in area and has maximum depth of 3.5 m at high water level. The lake is located in a lake-swamp complex with River Rwizi as the principle inflow, and a number of peripheral lakes among which are four major ones, i.e. Lakes Nakivali, Mburo, Kachira, and Kijanebalola. The survey therefore established that Lake Nakivali is a healthy ecosystem capable of sustaining fisheries production. While stock enhancement through restocking with fry could boost fish stocks, especially of the Nile tilapia, effective management measures that allow natural regeneration of stocks of indigenous fish species is paramount. This may require closed fishing seasons and control of fishing effort. Tank aquaculture is a viable option for increasing fish production and Ngege (O. niloticus) and Male (C. gariepinus) are candidate fish species for fish farming.

Lake Albert fisheries resources and their management strategy

Lake Albert/Mobutu lies along the Zaire-Uganda border in 43/57 per cent ratio in the faulted depression tending south-west to the north east. It is bounded by latitudes 1o0 n to 2o 20’ N and longitudes 30o 20’ to 31o 20’E. It has a width varying from 35 to 45 km (22 to 28 miles) as measured between the scarps at the lake level. It covers an area of 5600km2 and has a maximum depth of 48m. The major inflow is through the Semiliki, an outflow of Lake Edward, Muzizi and Victoria Nile draining lakes Victoria and Kyoga while the Albert Nile is the outflow. The physical, chemical and biological productivity parameters are summarized in Table 1. The scarp is steep but not sheer and there are at least 4 tracks leading down it to villages on the shore and scarp land scarp is a young one, formed as a result of earth movements of the Pleistocene times, and the numerous streams come down headlong down its thousand feet drop, more often than not in falls (Baker, 1954). Sometimes there appears to be a clean fault; and at other places there is the appearrence of step faulting, although this may be of only a superical nature .The escarpment’s composed of rocks belonging to the pre-Cambrian Basement complex of the content; but the floor of the depression is covered with young sedimentary rocks, known as kaiso beds. In their upper part these latter beds contains many pebbles; whilst low down the occurrence fossiliferous beds is sufficiently rare phenomenon in the interior plateau of Africa. The kaiso beds dated as possibly middle Pleistocene in age, are exposed in various flats on the shore, and they presumably extend under the relatively shallow waters of the lake. A feature of the shore is the development of sandpits and the enclosure of lagoons; and these can be observed in various stages of development at kaiso, Tonya, kibiro, Buhuka and above all, at Butiaba. On an island lake over 1100 km (700 miles) from the shores of the Indian Ocean one can thus study some of the shore-line phenomena usually associated with the sea- coast (Worthington, 1929). In the north, from Butiaba onwards, the flats become wider and from a continuous lowland as the lake shore curves away from the straight edge of the escarpment. At a height of just 610m (2000 feet) above sea-level, the rift valley floor at Butiaba has a mean annual temperature of 25.60c (780 f), from which there is virtually no seasonal variation; and and the mean daily range is only 6.50c (130f) (E.Afr. met. Dept.1953). With a mean annual rainfall of not much more than 762mm (309 inches) and only 92 rain days in ayear, again to judge from Butiaba, conditions in the rift valley are semi-arid; and the vegetation cover consists of grasses and scattered drought-resisting trees and bushes. Only near the stream courses does the vegetation thicken.

Separation and identification fresh water leeches of waters resources in Kordistan Province

In the primary studying, known leeches have included into free living and parasitic which the parasitic group, besides of direct impacts like: growth detraction, anemia, making wound in the connecting part with the skin, with making plat for secondary bacterial and molding infections in the toll place, is able to cause to transfer blood flagellate and virus to the fish too. Therefore, by accusing information related to fauna leeches of each area a risk factor from the viewpoint of the possibility of being or accusing transferred diseases by these leeches, one can predict and forehand about them. Freshwater leeches of Iran to present accurate recognition (morphological, molecular) have not been, and there are some limited reports from different parts of the country about them. One of the areas that its leeches have not been identified yet is Kurdistan, By having five latrines and big permanent rivers and 32000 springs and a lot of deep and semi-deep wells and this province is a convenient bed for growing aquatics in the country. Therefore, identifying risk factors for development of aquaculture on water resources is one important factor to access achieving development goals. For recognizing leeches of this province, some samples from 10 stands were token. Samples from under stones, sticking to the fish, turtles, plants and solid substances in the water were separated and after recording their physical characteristics, calming with 10% ethylic alcohol with 10% formalin become fixed and after painting with Carmen acetic acid by standard keys for 7 species of Helobdella stagnalis, Placobdella costata, Hemiclepsis marginata, Erpobdella octoculata, Hirudo medicinalis, Dina lineate lineata have been identified and described. Which Helobdella stagnalis has the highest distribution in the province and the minimum one is Hirudo medicinalis. However, that the data obtained in leeches in Kurdistan is a relatively complete collection in this research, recognizing fauna of these areas needs more studying. The Placobdella costata and Hemiclepsis marginata sticking to the fish were separated among identified species which showed that these are parasites for the fish. The sticking area of those leeches to the skin was accompanied with scales cast, damage to mucous membranes beneath the parasite and bleeding Was associated with Histopathology studying effect includes observing break and disconnection in the leech connecting place to the epithelial layer of epidermis in the skin, destroyed nucleus in skin Epithelial cells with observing necrosis in ulcerative place become of the leech and the sub acute inflammated penetration until acute necrosis with opening in Dermis layer is observable. Kidney of this fish have changes such as: proliferation, like proliferative kidney disease with increasing proliferative glomerular cells and increasing in membranous cells in Capillary corpuscle, observing necrotic cells in haematopoietic tissue of kidney along with increasing in infiltration of leukocyte's cells generally mono nucluars such as lymphocytes and less poly morpho nucluars such as neutrophiles that are symptoms of disorders causing anemia become of nourishing and sucking blood by the leech and creating a chronic kidney infection that originally root is in another place like the skin. Also Hemorrhagic anemia causes losing RBC's is because of using the host blood by the leech. (In this situation, one can see immature RBC red cells in Peripheral blood. To identify potential carriers of the leech to the viruses, after finding them in recorded stands and putting them in 75% ethanol for viruses cause IPN, VHS, IHN, they were tested by PCR that the conclusion of these experiments approved IPN virus in Hemiclepsis marginata and Hirudo medicinalis. This kind of leeches can act like a mechanical carrier and causing spreading the agent of this disease. It is worth mentioning that studying the pathogenicity of this virus for aquaculture sources, mentioned before needs more research. During the study of infected fish with leeches that was done after preparing bloody slides and staining them, no case blood parasites was observed. During a research about infecting fish experimentally to known leeches it become clear that 5 days after being in aquarium including leeches, samples of sticking Hirudo medicinalis leech to the golden carp with scales cast were observed. Including leeches to the fish started with molting the scales in the sticking area in the fish and fish become too uneasy and by rubbing themselves to the malls and things inside the aquarium, tried to separate them. Finally, after around 30 hours, leeches penetrate the skin, feeding from blood and tissue liquids and cause mortality the fish and then they become separated from them. If the corpse of these fish stayed in the aquarium, the Helobdella stagnalis and Erpobdella octoculata would start feeding them.