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Lake Kivu

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Lake Kivu
meromictic lake, lake
Part ofAfrican Great Lakes Edit
Native labelLake Kivu Edit
InflowsKarundura Edit
OutflowsRuzizi River Edit
Basin countryRwanda Edit
CountryDemocratic Republic of the Congo, Rwanda Edit
Coordinate location1°51′11″S 29°8′7″E Edit
Map

Lake Kivu be one of de African Great Lakes.[1] E dey lie for de border between de Democratic Republic of de Congo den Rwanda top, den e dey for de Albertine Rift insyd, de western branch of de East African Rift.[2] Lake Kivu dey empty into de Ruzizi River, wey dey flow southwards into Lake Tanganyika.[3] For 1894 insyd, German officer den colonial ruler Gustav Adolf von Götzen be de first European wey dem record to visit de lake.

Kivu lake shoreline at Gisenyi, Rwanda

For de past insyd, Lake Kivu drain toward de north, wey e contribute to de White Nile. About 13,000 to 9,000 years ago, volcanic activity block Lake Kivu ein outlet to de watershed of de Nile.[4] De volcanism produce mountains, wey dey include de Virungas, wey rise between Lake Kivu den Lake Edward, to de north.[5] Dem then force water from Lake Kivu south down de Ruzizi. Dis, for turn insyd, raise de level of Lake Tanganyika, wey ovaflow down de Lukuga River.[4]

Lake Kivu be one of three lakes for de world insyd, along plus Lake Nyos den Lake Monoun, dat dey undergo limnic eruptions (wey ovaturn of deepwater stratified layers dey release dissolved carbon dioxide (CO2)). De lake ein bottom dey sanso contain methane (CH4). If a limnic eruption dey occur, de lives of de two million pippoe wey dey live nearby go be for danger insyd.

Geography

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Lake Kivu dey approximately 42 km (26 mi) long den 50 km (31 mi) at ein widest.[1] Ein irregular shape dey make measuring ein precise surface area difficult; dem estimate am to cover a total surface area of sam 2,700 km2 (1,040 sq mi), wey e make am Africa ein eighth largest lake.[3] De surface of de lake dey sit at a height of 1,460 metres (4,790 ft) above sea level. Dis lake get a chance of suffering a limnic eruption every 1000 years.[1] De lake get a maximum depth of 475 m (1,558 ft) den a mean depth of 220 m (722 ft), wey e make am de world ein twentieth deepest lake by maximum depth, den de thirteenth deepest by mean depth.[1]

De lake bed dey sit upon a rift valley wey dem slowly pull am apart, wey e cause volcanic activity for de area insyd.

De world ein tenth-largest island for a lake insyd, Idjwi, dey lie for Lake Kivu insyd

Human geography

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Sam 1,370 square kilometres (529 sq mi) anaa 58 percent of de lake ein waters dey lie within DRC borders.[3]

Settlements for de lake ein shore top dey include Bukavu, Kabare, Kalehe, Sake den Goma for de Democratic Republic of the Congo insyd, den Gisenyi, Kibuye, den Cyangugu for Rwanda insyd.

For early 2025 insyd, during de M23 campaign, de Rwandan military occupy all settlements for de Congolese side of de lake ein shores insyd den de M23 Movement, plus provincial capital Goma wey dem capture for January insyd den all settlements wey dey under M23 control as of early March.[6] For 12 March insyd, M23 land for Idjwi island top, wey e occupy am without resistance.[7]

Chemistry

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Lake Kivu be a meromictic lake wey dey contain a freshwater surface layer dat dey becam more saline plus depth, plus a salinity wey dey approach 6 g/kg near de bottom.[8] Along plus Cameroonian Lake Nyos den Lake Monoun, Lake Kivu be one of three dat dem know to undergo limnic eruptions (wey ovaturn of deepwater stratified layers dey release dissolved carbon dioxide). Around de lake, researchers find evidence of massive local extinctions about every thousand years, wey outgassing events presumably cause am. De trigger give lake ovaturns for Lake Kivu insyd, dem no know am, but volcanic activity den changes for climate insyd, dem suspect both.[9] De gaseous chemical composition of exploding lakes be unique to each lake. For Lake Kivu ein case, e dey include methane (CH4) den carbon dioxide (CO2), as a result of lake water interaction plus volcanic hot springs.[10]

De amount of methane wey dem contain am at de bottom of de lake, dem estimate am to be 65 cubic kilometres (16 cu mi). If dem burn am for a modern combined-cycle generating plant insyd, dat amount of methane go generate around 40,000 megawatts give an entire year, wey dey equivalent to de power output equivalent to six times dat of de Grand Coulee Dam at peak springtime power. De lake sanso dey hold an estimated 256 cubic kilometres (61 cu mi) of carbon dioxide wey, if dem release am for an eruption event insyd, e fi suffocate all of de inhabitants of de lakeshore.[11] De water temperature be 24 °C (75 °F), den de pH dey about 7 for de anoxic region insyd, den around 9 for de oxygenated waters insyd.[12] Dem report say microbial reduction of de volcanic produce methane (CO2).[13] A future ovaturn den gas release from de deep waters of Lake Kivu go result for catastrophe insyd, wey dey dwarf de historically lake ovaturns dem document at de much smaller Lakes Nyos den Monoun. De lives of de approximately two million pippoe wey live for de lake basin area insyd, dem go threaten am.[10]

Cores from de Bukavu Bay area of de lake reveal dat de bottom get layered deposits of de rare mineral monohydrocalcite wey dem interlay plus diatoms, for top of sapropelic sediments plus high pyrite content. Dem find'em at three different intervals. Dem believe de sapropelic layers to be related to hydrothermal discharge den de diatoms to a bloom wey reduce de carbon dioxide levels low enough to precipitate monohydrocalcite.[14]

Scientists hypothesize dat sufficient volcanic interaction plus de lake ein bottom water dat get high gas concentrations go heat water, force de methane out of de water, spark a methane explosion, den trigger a nearly simultaneous release of carbon dioxide, though de entry of 1 million cubic meters of lava during de January 2002 eruption get no effect.[15][16] De carbon dioxide go then suffocate large numbers of pippoe for de lake basin insyd as de gases roll off de lake surface. E sanso dey possible say de lake fi spawn lake tsunamis as gas dey explode out of am.[17][18][19]

Dem begin to understand de risk wey Lake Kivu pose during de analysis of more recent events at Lake Nyos. Dem originally think Lake Kivu ein methane to be merely a cheap natural resource give export, den give de generation of cheap power. Once de mechanisms wey cause lake ovaturns begin to be understood, so do awareness of de risk de lake pose to de local population.

Dem install an experimental vent pipe at Lake Nyos for 2001 insyd to remove gas from de deep water, but such a solution give de much larger Lake Kivu go dey considerably more expensive. De approximately 510 million metric tons (500×10^6 long tons) of carbon dioxide for de lake insyd be a little under 2 percent of de amount wey human fossil fuel burning release am annually. Therefore, de process of releasing am fi potentially get costs beyond simply building den operating de system.

Dis problem wey dem associate plus de prevalence of methane be dat of mazuku, de Swahili term "evil wind" give de outgassing of methane den carbon dioxide dat dey kill pippoe den animals, den fi even kill vegetation when for high enough concentration insyd.

Methane extraction

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A methane extraction platform, Gisenyi, Rwanda.

Dem recently find Lake Kivu to contain approximately 55 billion m3 (1.9 trillion cu ft) of dissolved biogas at a depth of 300 metres (1,000 ft). Until 2004, dem do extraction of de gas for a small scale top, plus dem use extracted gas to run boilers at de Bralirwa brewery for Gisenyi insyd.[20][21] As far as large-scale exploitation of dis resource dey concern, de Rwandan government negotiate plus a number of parties to extract methane from de lake.

Biology den fisheries

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Fishing boats for Lake Kivu top, 2009
Paradis Malahide Island within de lake
De sky wey reflect for Lake Kivu top

De fish fauna for Lake Kivu insyd be relatively poor plus 28 described species, wey dey include four introduced species.[22] De natives be de Lake Rukwa minnow (Raiamas moorii), four species of barb (ripon barbel, Barbus altianalis, East African red-finned barb, Enteromius apleurogramma, redspot barb, E. kerstenii den Pellegrin's barb, E. pellegrini), an Amphilius catfish, two Clarias catfish (C. liocephalus den C. gariepinus), Nile tilapia (Oreochromis niloticus) den 15 endemic Haplochromis cichlids.[22] Another c. 20 possibly undescribed species of cichlids, dem know from de lake.[23] De species dem introduce be three cichlids, de longfin tilapia (Oreochromis macrochir), blue-spotted tilapia (O. leucostictus) den redbreast tilapia (Coptodon rendalli), den a clupeid, de Lake Tanganyika sardine (Limnothrissa miodon)[22][24][25] Dem refer sardine to locally as 'Ndagala' anaa 'Isambaza'.[26]

De exploitable stock of de Lake Tanganyika sardine, dem estimate am at 2,000–4,000 metric tons (2,000–3,900 long tons) per year.[27] Dem introduce am to Lake Kivu for late 1959 insyd by de Belgian agronomist Alphonse Collart.[24][25] An attempt to introduce de similar Lake Tanganyika sprat (Stolothrissa tanganicae) at de same time be unsuccessful.[26]

At present, Lake Kivu be de sole natural lake for wey L. miodon, a sardine dem originally restrict to Lake Tanganyika, dem introduce am initially to fill an empty niche. Prior to de introduction, no planktivorous fish dey present for de pelagic waters of Lake Kivu insyd. For de early 1990s insyd, de number of fishers for de lake top be 6,563, wey 3,027 dey associated plus de pelagic fishery den 3,536 plus de traditional fishery. De widespread armed conflict for de surrounding region insyd from de mid-1990s result for a decline for de fisheries harvest insyd.[28]

Following dis introduction, de sardine gain substantial economic den nutritional importance give de lakeside human population but from an ecosystem standpoint, de introduction of planktivorous fish fi result for important modifications of plankton community structure insyd. Recent observations show de disappearance during de last decades of a large grazer, Daphnia curvirostris, den de dominance of mesozooplankton community by three species of cyclopoid copepod: Thermocyclops consimilis, Mesocyclops aequatorialis den Tropocyclops confinis.[29][30]

Dem release first comprehensive phytoplankton survey for 2006 insyd.[31] Plus an annual average chlorophyll for de mixed layer insyd of 2.2 mg m−3 den low nutrient levels for de euphotic zone insyd, de lake be clearly oligotrophic. Diatoms be de dominant group for de lake insyd, particularly during de dry season episodes of deep mixing. During de rainy season, de stratified water column, plus high light den lower nutrient availability, favour dominance of cyanobacteria plus high numbers of phototrophic picoplankton.[31][32][33][34] De actual primary production be 0.71 g C m−2 d−1 (≈ 260 g C m−2 a−1).[35]

A study of evolutionary genetics show dat de cichlids from lakes for northern Virunga insyd (e.g., Edward, George, Victoria) go fi dey evolve for a "proto-lake Kivu" insyd, much older dan intense volcanic activity (20,000-25,000 years ago) wey cut de connection.[36] De elevation of de mountains west of de lake (wey currently be de Kahuzi-Biega National Park, one of de largest reserves of eastern lowland (anaa Grauer's) gorillas for de world insyd), wey dem combine plus de elevation of de eastern rift (wey dem locate for eastern Rwanda insyd) go dey responsible give de drainage of water from central Rwanda for de actual Lake Kivu insyd. Lack of consistent geological evidence challenge dis concept of "proto-lake Kivu"[37], although de cichlid ein molecular clock dey suggest de existence of a lake much older dan de commonly cited 15,000 years.

Lake Kivu be de home of four species of freshwater crab, wey dey include two non-endemics (Potamonautes lirrangensis den P. mutandensis) den two endemics (P. bourgaultae den P. idjwiensis).[38] Among Rift Valley lakes, Lake Tanganyika den Lake Victoria be de only oda plus endemic freshwater crabs.[38][39]

Illegal fishing

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For 2018 insyd, dem record ova 400 cases of potential illegal fishing for Lake Kivu top. According to de Animal Research den Technology Transfer at de Rwanda Agricultural Board, fish production for Kivu Lake insyd drop from 24,199 tonnes for de 2017–2018 fishing season insyd to 16,194 tonnes for 2019–2020 insyd,[40] wey Deputy Director Solange Uwituze attribute to fishing methods dat dey affect fish reproduction. Between May den July 2020, Rwanda Police Marine Unit operations report 27 cases wey dey include 10 poachers dem arrest give illegal fishing for de lake top.[41][42]

Islands

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  • Idjwi (part of Idjwi Territory, South Kivu Province)
  • Nyamunini (dem sanso know am Napoleon Island)
  • Amahoro
  • Iwawa
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References

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  1. 1 2 3 4 Scheffel, Richard L.; Wernet, Susan J., eds. (1980). Natural Wonders of the World. United States of America: Reader's Digest Association, Inc. pp. 206–207. ISBN 978-0-89577-087-5.
  2. ↑ Wong, H.-K.; Herzen, R. P. (1974-06-01). "A Geophysical Study of Lake Kivu, East Africa". Geophysical Journal International. 37 (3): 371–389. Bibcode:1974GeoJ...37..371W. doi:10.1111/j.1365-246x.1974.tb04091.x. ISSN 0956-540X.
  3. 1 2 3 "The Largest Lakes in Africa". WorldAtlas. 15 June 2020.
  4. 1 2 Danley, Patrick D.; Husemann, Martin; Ding, Baoqing; Dipietro, Lyndsay M.; Beverly, Emily J.; Peppe, Daniel J.; et al. (2012). "The Impact of the Geologic History and Paleoclimate on the Diversification of East African Cichlids". International Journal of Evolutionary Biology. 2012: 1–20. doi:10.1155/2012/574851. PMC 3408716. PMID 22888465.
  5. ↑ Clark, J. D. (1969). Kalambo Falls Prehistoric Site, Volume 1. London: Cambridge University Press. p. 34. Retrieved 16 January 2013.
  6. ↑ "RDC: sur les 8 territoires que compte le Sud-Kivu, 7 sont désormais sous occupation après l'arrivée sans combat des rebelles de l'AFC/M23 au territoire insulaire d'Idjwi" [DRC: Of the eight territories in South Kivu, seven are now under occupation following the arrival of AFC/M23 rebels in the island territory of Idjwi without a fight]. Actualite.cd (in French). 14 March 2025. Retrieved 14 March 2025.
  7. ↑ "Congo War Security Review, March 4, 2025". Critical Threats. Retrieved 2025-03-05.
  8. ↑ Sommer, Tobias; Schmid, Martin; Wüest, Alfred (2019). "The role of double diffusion for the heat and salt balance in Lake Kivu". Limnology and Oceanography (in English). 64 (2): 650–660. Bibcode:2019LimOc..64..650S. doi:10.1002/lno.11066. ISSN 1939-5590.
  9. ↑ Fowkes, Neville; Mason, David; Hutchinson, A.J. (2018). Proceedings of the Mathematics in Industry Study Group: Emissions from Lake Kivu (PDF). University of the Witwatersrand. pp. 27–73. ISBN 978-0-9870336-8-0. Retrieved 11 October 2022.
  10. 1 2 Wenz, John (2020). "The danger lurking in an African lake". Knowable Magazine. doi:10.1146/knowable-100720-1. S2CID 225118318.
  11. ↑ "The Explosive Hazard Hiding in an African Lake". Smithsonian Magazine.
  12. ↑ Njala University, Sierra Leone; Olapade, Oj; Omitoyin, Bo; University of Ibadan, Nigeria (2012-08-03). "Anthropogenic pollution impact on physico-chemical characteristics of Lake Kivu, Rwanda". African Journal of Food, Agriculture, Nutrition and Development. 12 (53): 6517–6536. doi:10.18697/ajfand.53.9840. hdl:1807/55851. S2CID 70874696.
  13. ↑ Nayar, Anjali (2009). "A lakeful of trouble". Nature. 460 (7253): 321–323. doi:10.1038/460321a. PMID 19606123.
  14. ↑ "Stoffers, P., and Fischbeck, R. (1974) Monohydrocalcite in the sediments of Lake Kivu (East Africa) Sedimentology, 21, 163–170.
  15. ↑ Seach, John (January 17–25, 2002). "Archived Volcano News - John Seach". volcanolive.com. Retrieved 2023-02-07.
  16. ↑ Halbwachs; et al. (2002-03-09). "Investigations in Lake Kivu (East Central Africa) after the Nyiragongo Eruption of January 2002: Specific study of the impact of the sub-water lava inflow on the lake stability" (PDF). Solidarities. Retrieved 2012-12-21. mirror
  17. ↑ "Rwanda and DRC Sign Agreement Over L. Kivu Methane Gas Exploration". newsghana.com.gh (in American English). November 21, 2015. Retrieved 2023-02-07.
  18. ↑ "Killer Lakes - Transcript". BBC. April 4, 2002. Retrieved 2023-02-07.
  19. ↑ "In the Shadow of Doom" Archived 2007-09-28 at the Wayback Machine, The Walrus, May 2006
  20. ↑ "Case Studies : Recovery of Gas from Lake Kivu – The Goats of Rwanda" Archived 2006-02-24 at the Wayback Machine, Added Value Engineering Consultants, accessed 4 May 2007
  21. ↑ Adam Mynott (May 4, 2007). "Rwanda's Underwater Powerhouse". BBC News. Retrieved 2008-02-05.
  22. 1 2 3 Snoeks, J; De Vos, L.; Thys van den Audenaerde, D. (1997). "The ichthyogeography of lake Kivu". South African Journal of Science. 93: 579–584.
  23. ↑ Walker, J. (2013). "How many species are there in Lake Kivu?" (PDF). Institute of Ecology and Evolution. University of Bern.{{cite journal}}: CS1 maint: date and year (link)
  24. 1 2 Collart, A. (1960). "L'introduction du 'Stolothrissa tanganicae' (Ndagala) au lac Kivu". Bulletin Agricole du Congo Belge. Hosted at Agricultural Research Archive for DRC, Rwanda and Burundi, 1885-1960 (in French). 51 (4).
  25. 1 2 Capart, A. (1959). "A propos de l'introduction du Ndakala (Stolothrissa tanganikae) dans le lac Kivu". Bulletin Agricole du Congo Belge et du Ruanda-Burundi (in French). 50 (4).
  26. 1 2 Collart, Alphonse (June 1989). "Introduction et acclimatation de l'Isambaza du lac Tanganyika au lac Kivu". Compte rendu du seminaire trente ans apres l'introduction de l'Isambaza au lac Kivu (RWA/87/012/DOC/TR/16) (in French). Gisenyi, Rwanda: Food and Agriculture Organization of the United Nations.
  27. ↑ Marshall, B. E. (1991). "Seasonal and annual variations in the abundance of the clupeid Limnothrissa miodon in lake Kivu". Journal of Fish Biology. 39 (5): 641–648. Bibcode:1991JFBio..39..641M. doi:10.1111/j.1095-8649.1991.tb04394.x.
  28. ↑ "INFORMATION ON FISHERIES MANAGEMENT IN THE DEMOCRATIC REPUBLIC OF THE CONGO". fao.org. January 2001. Archived from the original on March 15, 2006. Retrieved June 26, 2023.
  29. ↑ Isumbisho, M (2006). Zooplankton ecology of Lake Kivu (Eastern Africa). Belgium: University of Namur. ISBN 978-2-87037-534-1.
  30. ↑ Isumbisho, M.; Sarmento, H.; Kaningini, B.; Micha, J.-C.; Descy, J.-P. (2006). "Zooplankton of Lake Kivu, East Africa, half a century after the Tanganyika sardine introduction" (PDF). Journal of Plankton Research. 28 (11): 971–989. doi:10.1093/plankt/fbl032. Archived from the original (PDF) on 2012-03-12. Retrieved 2011-04-23.
  31. 1 2 Sarmento, H. (2006). Phytoplankton ecology of Lake Kivu (Eastern Africa) (PDF). Belgium: University of Namur. ISBN 978-2-87037-532-7. Archived from the original (PDF) on 2016-01-17. Retrieved 2011-04-23.
  32. ↑ Sarmento, H.; Isumbisho, M; Descy, JP (2006). "Phytoplankton ecology of Lake Kivu (eastern Africa)" (PDF). Journal of Plankton Research. 28 (9): 815–829. doi:10.1093/plankt/fbl017. Archived from the original (PDF) on 2015-09-24. Retrieved 2011-04-23.
  33. ↑ Sarmento, H.; et al. (2008). "Abundance and distribution of picoplankton in tropical, oligotrophic Lake Kivu, eastern Africa" (PDF). Freshwater Biology. 53 (4): 756–771. Bibcode:2008FrBio..53..756S. doi:10.1111/j.1365-2427.2007.01939.x.
  34. ↑ Sarmento, H.; et al. (2007). "Species diversity of pelagic algae of Lake Kivu (East Africa)" (PDF). Cryptogamie-Algologie. 28 (3): 245:269. Archived from the original (PDF) on 2015-09-24. Retrieved 2011-04-23.
  35. ↑ Sarmento, H.; et al. (2009). "Phytoplankton ecology of Lake Kivu (eastern Africa): biomass, production and elemental ratios" (PDF). International Association of Theoretical and Applied Limnology, Vol 30, Pt 5, Proceedings. 30 (5): 709–713. Bibcode:2009SILP...30..709S. doi:10.1080/03680770.2009.11902221. hdl:2268/139009. Archived from the original (PDF) on 2015-09-24. Retrieved 2011-04-23.
  36. ↑ Verheyen, E. (2003). "Origin of the Superflock of Cichlid Fishes from Lake Victoria, East Africa". Science. 300 (5617): 325–329. Bibcode:2003Sci...300..325V. CiteSeerX 10.1.1.584.2497. doi:10.1126/science.1080699. PMID 12649486. S2CID 84478005.
  37. ↑ Stager, J. C. (2003). "Comment on "Origin of the Superflock of Cichlid Fishes from Lake Victoria, East Africa"". Science. 304 (5673): 963b. doi:10.1126/science.1091978. PMID 15143263.
  38. 1 2 Cumberlidge, N., and Meyer, K. S. (2011). A revision of the freshwater crabs of Lake Kivu, East Africa. Journal Articles. Paper 30.
  39. ↑ Cumberlidge, Neil; Clark, Paul F. (2017). "Description of three new species of Potamonautes MacLeay, 1838 from the Lake Victoria region in southern Uganda, East Africa (Brachyura: Potamoidea: Potamonautidae)". European Journal of Taxonomy (371). doi:10.5852/ejt.2017.371. hdl:10141/622400.
  40. ↑ "Illicit fishing threatens biodiversity in Lake Kivu". 26 January 2021. Retrieved 2023-06-23.
  41. ↑ ENACTAfrica.org (2022-01-31). "Tipping the scales of illicit fishing in Lake Kivu". ENACT Africa (in English). Retrieved 2022-03-24.
  42. ↑ ISSAfrica.org (2022-02-02). "Tipping the scales of illicit fishing in Lake Kivu". ISS Africa (in English). Retrieved 2022-03-24.
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