143 resultados para Waste disposal in the ocean


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In studying hydrosphere, atmosphere, and biosphere interactions, it is useful to focus on specific subsystem processes and energy exchanges (forcing). Since subsystem scales range over ten orders of magnitude, it may be difficult to focus research on scales that will yield useful results in terms of establishing causal and predictive connections between more easily and less easily observed subsystems. In an effort to find pertinent scales, we have begun empirical investigations into relationships between atmospheric, oceanic, and biological systems having spatial scales exceeding 10^3 kilometers and temporal scales of six months or more.

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The impact of waste discharge on fishery resources is a matter of great concern. The accepted norm in all environmental impact assessment studies is to avoid areas of high fishery potential while locating a marine outfall. Contemplating on this aspect a case study was conducted in the Amba River estuary before and after the establishment of a petrochemical complex at Nagothane. The treated wastewater from this complex is released through a subsurface outfall after adopting effective control measures for marine disposal of waste. Experimental trawling was done at five locations covering a distance of 30 km during 1990 to 1991. The catch rate within the estuary varied from 0.6 to 255 kg/h (av 24 kg/h). The trend indicated considerable decrease in fishery potential from the mouth of the estuary (av 64 kg/h) to the upstream location (av 11 kg/h). A total of 49 species of fishes, 16 species of prawns, 7 species of crabs and 1 species of lobster were identified from the collections. Number of species gradually increased from the interior segment at Dharamtar (8) to the outer area near Revas (18). A comparison of the quantitative and qualitative nature of the post outfall and pre outfall data revealed only marginal difference. The study indicates that if necessary precautions are taken to render the waste harmless the marine ecology will hardly be affected.

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Since the inception of the tuna long line fishery in the Indian Ocean in 1952, an annual average of 10% of the number of tunas and spear fishes caught continues to be damaged by sharks. In spite of the fact that this method of fishing for tunas is also resulting in the exploitation of a significant quantity of the tuna-preying sharks, the extent of the damage by these predators continues to be fairly constant. Quite often the damaged tunas are acceptable to the market, especially for canning. On the other hand report of damage caused by killer-whales, occasional at the beginning of the fishery in the Indian Ocean, has been increasing in frequency each year and since 1960 tuna fishermen have been desperately calling for ways and means of reducing the damage caused by these mammals. Unlike sharks killer-whales do not get hooked on the tuna long line; and tunas damaged by killer-whales are almost always unfit even for canning. The problem of predation by killer-whales exists not only in the whole of the Indian Ocean including the Timor and Banda Seas but also in the Atlantic and Pacific Oceans, especially in the seas around New Guinea, Samoa, Caroline and Marshal Islands. The seriousness of this problem of predation was highlighted at the annual tuna research conference held in Kochi, Japan, in February 1963, and steps were taken to devote considerable attention to this problem.

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Since the commencement of the exploitation of oceanic tuna resources of the Indian Ocean seventeen years ago, the hooked rates for the tuna species have declined in many areas of the Ocean but there are no evidences of such a trend in the case of the sharks. As a result, the percentage composition of sharks in the longline catches and the percentage of the tuna catch damaged by sharks show an increase. Hence there is an urgent need for innovation of the existing longline gear in order to increase the fishing efficiency for hooking the tuna species with a corresponding reduction in its efficiency for hooking sharks. At the beginning of this fishery, hooked sharks were discarded at sea, at a later stage the liver and fins were taken and the carcass discarded and presently the sharks are also brought along with the tuna catch. Though the shark meat has a very low market value it is brought in order to cover up for the declining tuna catches. Thus it has become very necessary to increase the demand for shark meat by developing products or by-products utilizing shark meat and ensuring the successful continuity of the tuna longline fishery. The pattern of distribution of shark species in the time grounds of the Pacific, Indian and Atlantic Oceans and also the predation of hooked tunas by sharks were discussed earlier (Sivasubranianiam 1963, 1964 and 1966). Some contribution to these studies is made in this paper based on new data become available.

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The present report was prepared to evaluate the performance of two fishing vessels, study trends in fishing condition, the status of the stocks exploited and also to contribute basic information required by the Indian Ocean Fisheries Commission for management of the tuna resources.

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A comparative study was carried out between the two biggest creeks along the Arabian Gulf coast of the United Arab Emirates to evaluate impacts of sewage and industrial effluents on their hydrochemical characteristics. Surface and bottom water samples were collected from Abu Dhabi and Dubai creeks during the period from October 1994 to September 1995. The hydrochemical parameters studied were: temperature (21.10-34.00°C), salinity (37.37-47.09%), transparency (0.50-10.0 m), pH (7.97-8.83), dissolved oxygen (1.78-13.93 mg/l) and nutrients ammonia (ND- 13.12,ug-at N/1), nitrite (ND-6.66 ,ug-at N/1), nitrate (ND- 41.18 ,ug-at N/1), phosphate (ND- 13.06 ,ug-at P/1), silicate (0.68-32.50 ,ug-at Si/1), total phosphorus (0.26- 21.48 ,ug-at P/1), and total silicon (0.95- 40.32 ,ug-at Si/1). The present study indicates clearly that seawater of Abu-Dhabi Creek was warmer (28.l2°C) than Dubai (27.56°C) resulting in a higher rate of evaporation. Owing to more evaporation, salinity levels showed higher levels at Abu Dhabi (43.33%) compared to Dubai (39.03%) seawater. The study also revealed higher secchi disc readings at Abu Dhabi Creek (4.68 m) as compared to Dubai Creek (2.60 m) suggesting more transparency at Abu Dhabi Creek. Whereas, seawater of Dubai exhibited higher levels of pH (1.03 times), and dissolved oxygen (1.05 times) than Abu Dhabi seawater due to an increase in productivity. Meantime, seawater of Dubai showed higher tendency to accumulate ammonia (8.22 times), nitrite (10.93 times), nitrate (5.85 times), phosphate (10.64 times), silicate (1.60 times), total phosphorus (3.19 times), and total silicon (1.54 times) compared to Abu Dhabi seawater due to the enrichment of seawater at Dubai with domestic sewage waters which has distinctly elevated the levels of the nutrient salts particularly in inner-most parts of the creek leading to eutrophication signs. The changes occurred in the receiving creek water of Dubai as a result of waste-water disposal that have also reflected on the atomic ratios of nit: Effect of pollution rogen: phosphorus: silicon.

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Objectives included; a contribution to understanding large-scale processes affecting the Bay of Bengal Large Marine Ecosystem Project (BOBLME) and it's living resources; and to align with International Indian Ocean Expedition (IIOE-2) (2015-2020) which will extensively explore and study the Indian Ocean to improve understanding of the ocean and coupled climate processes.

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The small brachyuran family Raninidae Dana is represented in the Indo-West Pacific region by eight genera, with only some twenty species. One of the least known genera is Notopoides, which contains only a single species. This genus was first described by Henderson (1888) on the basis of material collected by H.M.S. "Challenger" from the Kei Islands, in the Banda sea off Indonesia. There have been no subsequent reports of this species in the ninety seven years since its original discovery. During the course of the study of the benthic fauna off the coast of East Africa, the Fisheries Research Vessel "Manihine" obtained five specimens of this rare species. These new records, collected during a short period of time, indicate that the species is probably not uncommon in this region, which also represents a great increase in its known geographical range. Specimens have been deposited in the collections of the National Museum, Nairobi, the Rijksmuseum van Natuurlijke Historie, Leiden, and the National Museum, Singapore: Catalogue numbers are crust. 1092 ; Crust. D. 28567; NMS. 1972.8.4.1, male of 35x26 respectively.