OJE  Vol.5 No.7 , July 2015
Ecological Devastation in Lake Victoria: Part A: Thermal Structure and Anoxia
Abstract: Lake Victoria is the second (excl. Caspian Sea) largest lake in the world by surface area and 7th by Volume. The lake and catchment territories are shared between three countries, Kenya, Uganda and Tanzania. A research was carried out during 1990-1992 exploring the changes of the thermo-chemical structure occurred after the invasion of Nile Perch. Results of changes of physico-chemical (Temperature, DO and pH) conditions are summarized in this paper. The anoxic conditions by space and time were enhanced. Enhancement of pollutant supply from anthropogenic developments of terrestrial sources and atmospheric dust deposition accompanied by the deleterious effects of the Nile Perch invasion caused enhancement of anoxia in the lake in space and time. The combination of bottom-up nutrient supply and strong mixing conditions, expressed as low RTR values accelerate phytoplankton growth rate and production. The surplus of organic matter originated from algal biomass, enhanced anoxia.
Cite this paper: Gophen, M. (2015) Ecological Devastation in Lake Victoria: Part A: Thermal Structure and Anoxia. Open Journal of Ecology, 5, 287-298. doi: 10.4236/oje.2015.57023.

[1]   Newell, B.S. (1960) Hydrology of Lake Victoria. Hydrobiologia, 15, 363-383.

[2]   Fryer, G. (1960) Concerning the Proposed Introduction of Nile Perch into Laken Victoria. East Africa Agriculture Journal, 267-270.

[3]   Barel, C.D.N., Dorit, R., Greenwood, P.H., Fryer, G., Hughes, N., Jackson, P.B.N., Kawanabe, H. and Lowe-McConell, R.H. (1985) Destruction of Fisheries in Africa’s Lakes. Nature, 325, 19-20.

[4]   Greenwood, P.H. (1981) The Haplochromine Fishes of East African Lakes: Taxonomy, Biology, and Evolution. Kraus International Publications, Munich, 839 p.

[5]   Ochumba, P.B.O., Gophen, M. and Pollingher, U. (1992) Ecological Changes in Lake Victoria after the Invasion of Nile Perch (Lates niloticus): The Catchment, Water Quality, and Fishery Management. Aquaculture and Schistosomiasis: Proceedings of the Network Meeting, Manila, National Academy Press, Washington DC, 137-147.

[6]   Ochumba, P.O.B., Gophen, M. and Pollingher, U. (1992) Management of Limnology and Fisheries of Lake Victoria: General Characteristics, Sociogeographic and Management of the Fisheries. Hydraulic Enigneering in Mexico, 7, 37-43.

[7]   Kaufman, L.S. (1992) Catastrophic Change in Species-Rich Freshwater Ecosystems: The Lesson of Lake Victoria. BioScience, 42, 846-858.

[8]   Ojwang, W.O., Ojuok, J.E., Nyamweya, C., Agembe, S., Owili, M., Yongo, E. and Wakwabi, E.O. (2014) The Intriguing Dynamics of Rastrineobola argentea Fishery in the Kenyan Waters of Lake Victoria. Aquatic Ecosystem Health and Management, 17.

[9]   Akiyama, T., Kajumulo, A.A. and Olsen, S. (1977) Seasonal Variation of Planktonand Physico-Chemical Condition in Mwanza Gulf, Lake Victoria. Bulletin of Freshwater and Fisheries Research Laboratory, 27, 49-61.

[10]   Asila, A. and Ogari, J. (1987) Growth Parameters and Mortality Rates of Nile Perch Lates niloticus Estimated from Length Frequency Data in the Nyanza Gulf (Kenya) Lake Victoria. UN-FAO-Fisheries Report, 389, 271-287.

[11]   Ochumba, P.B.O., Gophen, M. and Pollingher, U. (1994) Ecological Changes in Lake Victoria after the Introduction of Nile Perch (Lates niloticus): The Catchment, Water Quality and Fisheries Management. In: Cowx, I.G., Ed., Rehabilitation of Freshwater Fisheries (Fishing News Books), Chap. 31, Blackwell Scientific Publications Ltd., 338-347.

[12]   Ochumba, P.B.O., Gophen, M. and Pollingher, U. (1994) Ecological Changes in Lake Victoria after the Invasion by Nile Perch (Lates niloticus). In: Okemwa, E., Wakwabi, E.O. and Getabu, A., Eds., Recent Trends in Research on Lake Victoria Fisheries. Proceeding of the 2nd EEC Regional Seminar on Recent Trends in Research on Lake Victoria Fisheries Organized and Hosted by Kenia Marine and Fisheries Research Institute (KMFRI), Kisumu, 25-27 September 1991, ICIPE Science Press, 29-39.

[13]   Gophen, M., Ochumba, P.B.O. and Kaufman, L.S. (1995) Some Aspects of Perturbations in the Structure and Biodiversit of the Ecosystem of Lake Victoria. Aquatic Living Resources, 8, 27-41.

[14]   Talling, J.F. (1966) The Annual Cycle of Stratification and Phytoplankton Growth in Lake Victoria (East Africa). Internationale Revue der gesamten Hydrobiologie und Hydrographie, 51, 545-621.

[15]   Fish, G.R. (1957) A Seiche Movement and Its Effect on the Hydrology of Lake Victoria. Colonial Office Fishery Publications, London, No. 10, 1-60.

[16]   Gophen, M., Ochumba, P.B.O., Pollingher, U. and Kaufman, L.S. (1993) Nile Perch (Lates niloticus) Invasion in Lake Victoria (East Africa). Verhandlungen des Internationalen Verein Limnologie, 25, 856-859.

[17]   Reynolds, J.E. and Grebovall, D.F. (1988) Socio-Economic Effects of the Evolution on Nile Perch Fisheries in Lake Victoria: A Review. CIFA Technical Paper 17, 148 p.

[18]   Talling, J.F. (1957) Some Observations on the Stratification of Lake Victoria. Limnology and Oceanography, 2, 213-221.

[19]   Kitaka, G.E.B. (1971) An Instance of Cyclonic Upwelling in the Southern Offshore Waters of Lake Victoria. African Journal of Tropical Hydrobiology and Fisheries, 1, 85-92.

[20]   Hecky, R.E., Bugenyi, F.W.B., Ochumba, P.B.O., Talling, J.F., Mugidae, R., Gophen, M., Robinson, W. and Kaufman, L.S. (1994) Deoxygenation of the Deep Water of Lake Victoria, East Africa. Limnology and Oceanography, 39, 1476-1481.

[21]   Talling, J.F. (1969) The Incidence of Vertical Mixing and Some Biological and Chemical Consequences in Tropical African Lakes. Verhandlungen der Internationalen Vereinigung für theoretische und angewandte Limnologie, 17, 998-1012.