Hundreds of endemic species that evolved under the special conditions offered by the protection of Lake Victoria have been lost due to extinction, and several more are still threatened. [96] Increased logging and act of deforestation has led to environmental degradation around the region reducing the absorption of polluting chemicals and deteriorating the water quality.[97]. Learn how and when to remove this template message, "The Victoria Nyanza.
[80] The origin of the first Victoria introductions in the 1950s is not entirely clear and indisputable evidence is lacking. The fertility of tropical waters depends on the rate at which nutrients can be brought into solution. [60] Furthermore, Graham noted that the introduction of the European flax gill net of 5 inch mesh had undoubtedly caused a diminution in the number of ngege in those parts of the Kavirondo Gulf, the northern shore of the lake, the Sesse Islands and Smith's Sound which are conveniently situated close to markets.
For a comprehensiwe list of these islands, see: J. Prado, R.J. Beare, J. Siwo Mbuga & L.E.
The subsequent decrease in the number of algae-eating fish allows the algae to grow at an alarming rate, thereby choking the lake. The water since at least 12,000 years ago drained across a natural rock weir. [35][41][78], As early as the 1920s, it was proposed to introduce a large pelagic predator such as the Nile perch to improve the fisheries in the lake.
leucostictus). [35] Disregarding the haplochromines, the only native Victoria cichlids are two critically endangered tilapia, the Singida tilapia or ngege (Oreochromis esculentus) and Victoria tilapia (O.
Poissonneux, il se situe dans une région où le gibier ne manque pas, à l'ouest du réservoir Dozois et à environ 40 km à l'est du réservoir Decelles. With a surface area of approximately 59,947 km2 (23,146 sq mi),[10][11] Lake Victoria is Africa's largest lake by area, the world's largest tropical lake,[12] and the world's second-largest fresh water lake by surface area after Lake Superior in North America. In 1952, engineers acting for the government of British Uganda blasted out the weir and reservoir to replace it with an artificial barrage to control the level of the lake and reduce the gradual erosion of the rock weir. Oxygen concentrations in hypolimnetic waters (i.e. [36][41] The Victoria haplochromines are part of an older group of more than 700 closely related species, also including those of several smaller lakes in the region, notably Kyoga, Edward–George, Albert, and Kivu. Let the world see your experience through your eyes. It formed when westward-flowing rivers were dammed by an upthrown crustal block.
Le lac Victoria héberge quelques espèces d'annélides, de sangsues et d'oligochètes (comme Alma emini) et des rotifères (genres Brachionux et Anuraenopsis). The sand filtration helps reduce water-borne diseases and is based on the use of the local environment. [75], Lake Victoria supports Africa's largest inland fishery (as of 1997). Le Grand lac Victoria, dénommé Kitcisakik Sakaikan ou « lac de la grande embouchure » par les Algonquins, est un vaste élargissement de la rivière des Outaouais qui s'étend de la baie des Missionnaires, au sud, à la baie Kawastaguta, au nord.
As of 2016, an environmental data repository exists for Lake Victoria. The Kagera River is the largest river flowing into this lake, with its mouth on the lake's western shore. Located in the Beautiful Gatineau Valley, 58 miles north on route 11, from Ottawa, Canada. Local fisheries once depended on catching the lungfish, tilapia, carp and catfish that comprise the local diet. and P M. Kareiva, editors (1998).
[66][67] The last were first scientifically described in 2017 and very little is known about them: P. entebbe is only known from near Entebbe (the only known specimen was collected in 1955 and it is unknown if it was in or near the lake) and P. busungwe only at Busungwe Island in the northwestern part of the lake.