Benthic fauna of Ethiopian mountain streams and rivers

Transcription

1 Arh. Hydrobioi./Sul. 81 (Moograhishe Beitriige) Stuttgart, Jui 1988 Bethi faua of Ethioia moutai streams ad rivers By A.D. HARRISON ad H. B. N. HYNES With 1 figure ad 5 tables i the text Abstrat A faual stadard of referee is established for Ethioia motae bethos i udamaged high-level streams ad rivers. The effets of oulatio desity, soil erosio ad drought o soure waters is desribed. The Ethioia motae aquati faua is omared with the fauas of other Afria moutai regios ad its biogeograhial sigifiae is disussed. Cotets Itrodutio The Ethioia moutais The study regio Methods Results I. Physial ad hemial fators II. The faua Faua of the soure zoe. 2. Faua of stoy rus ad torrets 3. Faua of bakwaters ad quiet sots 4. Faua of moss i torrets Faua of margial vegetatio Faua of slow-flowig streams Faual idetifiatios ad seies distributio III. Disussio D.1 Effets of soil ad bed erosio o Ethioia moutai river faua. D.2 Pollutio of Ethio ia rivers.... D.3 Biogeograhy Biogeograhy of Afrotro ial moutai stream faua... Biogeograhial status of Ethioia moutai river faua. Im overished Ethioia rhithro Edemis i Ethioia rhithro D.4 Zoatio Summary Zoatio of Sub-Sahara motae streams ad rivers Zoatio i Ethioia motae rivers Zusammefassug. Akowledgmets. Referees Arhiv f. Hydrobiologie, Sul.-Bd /88/ $ E. Shweizerbart'she Verlagsbuhhadlug, D-7000 Stuttgart I

2 2 A.D. HARRISON ad H. B. N. HYNES Itrodutio The freshwaters of Ethioia, srigs, streams, rivers, lakes, imoudmets ad wells, ostitute a valuable rimary resoure of great biologial iterest ad strategi atioal imortae. At reset this resoure is utilized artially for hydroeletri ower, irrigatio, fisheries ad both idustrial ad otable water systems. The may soure streams ad rivers origiatig i the high eaks of the Rift Valley rages are of artiular imortae ad are threateed by erosio ad resultat atastrohi droughts. Ethioia's agriulture deeds to a ireasig extet o irrigatio water omig ultimately from the highlads. Sie World War II there has bee a raid irease i rural oulatio ad i domesti aimals, together with raid deforestatio i the moutais. Soil erosio has always bee a feature of the Ethioia highlads, ad the rih silt i the Blue Nile floods was the maistay of Aiet Egytia agriulture. However, reet raties have resulted i serious damage to the ulads (KuRu 1978), ad ow eormous quatities of silt are beig assed dow the rivers. This aer is a otributio towards the uderstadig of the high level motae soure waters whih suly the rivers ad ultimately the lakes ad imoudmets. This study is art of a extesive rogramme, joitly beig arried out by the Biology Deartmets of Addis Ababa Uiversity ad the Uiversity of Waterloo, o the freshwaters of Ethioia, with artiular emhasis o the Rift Valley draiage basis ad lakes. First, a desritio of the faua of relatively udamaged motae streams of Ethioia is give, establishig a basis for omariso with the faua of damaged streams, ad showig what deterioratio has already ourred. Seod, a omariso is made betwee the Ethioia motae stream ad river faua ad that of the moutais of East ad Souther Afria, ad Eurasia. The motae faua of Ethioia streams ad rivers is of biogeograhial imortae, as Ethioia moutais are the most ortherly of the sub-sahara high moutai rages ad lie o a ossible disersal route for motae forms to or from Afria, through the Arabia moutais to the Eurasia moutais. I East ad Souther Afria omrehesive surveys of flowig waters have bee made: the Great Berg River, Cae Fold Belt (HARRISON & ELSWORTH 1958, SoTT 1958); other Cae Provie rivers (HARRISON & AGNEW 1962); the Tugela River, Natal Drakesberg Moutais (OLIFF 1960); the Vaal River, Drakesberg (CHUTTER 1970); the Easter Trasvaal Drakesberg Moutais (HuGHES 1966); the Chimaimai Moutais, Easter Zimbabwe (HARRISON 1965 b); Mout Elgo, Ugada (HYNES & WILLIAMS 1962, WILLIAMS & HYNES 1971); Mout Keya, Keya (VAN SoMEREN 1950). Most of the Souther Afria fauisti surveys were art of omrehesive studies o water resoures. Researhers realized that the faual ommuities were very sesitive to deterioratio i rivers, aused by faulty agriultural raties ad

3 Bethi faua of Ethioia moutai streams ad rivers 3 by domesti ad idustrial ollutio. They saw the eed for establishig a faual stadard of referee derived from uolluted setios i the mai river systems whih would make ossible the detetio of future deterioratio (HARRISON & ELSWORTH 1958). Further iformatio o the distributio of seifi grous of aquati orgaisms may be gleaed from umerous taxoomi ubliatios, ad also from studies o the eology of seifi grous i the moutais of Zaire: STATZNER (1975, 1976) ad jaquemart & STATZNER (1981) o addisflies; LEHMANN (1979, 1981) o Chiroomidae. Util ow o iformatio has bee available o the omositio of bethi ommuities of Ethioia moutai streams ad rivers, although some iformatio o seifi taxoomi grous has bee give: HYNES (1955) o Heterotera; KIMMINS (1963) o Trihotera; FREEMAN & DE MEILLON (1953), UEMOTO, OGATA & MEBRAHTU (1977) ad GRENIER & OvAZZA (1956) o Simuliidae; FREEMAN (1955, 1956, 1957 ad 1958) o Chiroomidae; ad BROWN (1965) o freshwater sails. The Ethioia moutais Aordig to GoUIN (1979) the moutais of Ethioia were rodued by the major riftig roess whih started durig the middle Mioee ad otiued ito the Quarterary. Three reogizable dome segmets were rodued, two mai oes lyig to the orth-west ad to the south-east of the Rift Valley ad the third, a small segmet, lyig orth of Lake Turkaa (i Gama Goffa ad Kaffa). Both mai segmets have develoed ito moutai rages, with eaks risig to over 3000 m ad a few to just over 4000 m, ad extesive regios of high lateau. YALDEN (1983) states that 79.7% of the 28,545 km2 of moutais i Afria whih lie above 3000 m, ad 50.4% of the 371,432 km2 lyig above 2000 m are foud i Ethioia. Raifall i the moutais is high. Most falls durig two eriods, the first, alled the little rais, from Jauary to Aril ad the seod, the mai rais, from Jue to the ed of Setember. No moutai eak rises to above the ermaet sow lie so there are o ermaet glaiers as o Mt. Keya. The botaial zoes i the moutais are desribed by EDWARDS (1976). Above 3000 m, or dow to 2500 m i some laes, lats are Afro-alie or Subafroalie; the former are maily small bushy shrubs, but the latter may ilude tree-heather, ad eve small forests of Hageia abyssiia (BRUCE) J. F. GEMEL ad Hyerium revolutum VAHL (although muh of this has bee felled). Below this, dow to 2000 m is a zoe of juiers, ow mostly ut dow leavig srub ad eroded hillsides. The flat areas of the lateau are atural grasslads whih beome swamy durig the raiy seaso. The sloes of the wetter south ad west lateau ofte have forests of Podoarus grailior PIGLER, or remats of it. The

4 4 A. D. HARRISON ad H. B. N. HYNES uer esarmet, above the Rift Valley, has juier forest (juierus roera HoHsT. ex ENoL.), or its degraded remais; the lower esarmet sloes have evergree bushlad ad the Rift Valley floor has aaia bushlad or is ultivated. Aroud Addis Ababa, muh of the juier forest has bee relaed by eualytus latatios. The study regio Moutai streams ad rivers o both sides of the Rift Valley were studied durig 1983 ad The statios (ET) are show o Figure 1 ad listed i Table 1. Altitudes are take from otour mas sulied by the Ethioia Maig Agey, Addis Ababa. systems: The streams ad rivers samled were art of the followig river or losed lake 1. Abay (Blue Nile) River System : ET 5, 6, 7, 10, 15, 16, 17, Awash River System : ET 1, 1A, 2, 2A, 2B, 2C, 8, 9, 13, 14, 31, 32, 35, Geale - Juba River System: ET 19, 20, 21, 22, 23, 24, 25, Wabe Shebele River System: ET 27, 28, 29, Lake Awasa System: ET 3, 4, 11, Lake Abijata System: ET 33, Lake Abaya - Chamo System: ET 36, 37, 38. All statios had stoy rus exet ET 7, 8. ET 2, the Abo River, at 2500 m, had a waterfall with growths of moss whih was samled. Samles were also take from strog growths of moss ad Lemaea BoRY (Rhodohyta) at ET 19, the Daka River, at 3100 m. Samles were take from margial reeds ad rushes at a few statios, eg. ET 5 ad ET 30. Temeratures Methods These were take with a merury thermometer laed diretly i the ruig water. Water samles Samles were olleted i olythee bottles ad later aalyzed by the water aalysis laboratory of the Deartmet of Earth Siees, Waterloo: atios by atomi absortio aalysis, hloride ad sulhate by io hromatograhy usig a Diex System 12 io hromatograh, ad biarboate by titratio with stadard aid to a H edoit of 4.3. H Field H readigs were take i ruig water with a ortable H meter.

5 Bethi faua of Ethioia moutai streams ad rivers 5.-- ;... ) (.::::: E km!liiiil!li!!E:= ===:E====:3 Fig. 1 : Ma of the study re g io, showig otours at 1000 m itervals, ad riial draiages. Loatios of the umbered ET statios (Tab.1) are show as o e irles. Note: Weyib River is also selled Weyb, Web or Ueb.

6 6 A. D. HARRISON ad H. B. N. HYNES Table 1. Ethioia river statios samled. Water Ma referee Alt. River Zoe Date tem. ET E N m o 1 Dadi R. HR ' ' /12/ A Dadi R. Trib HR ' ' /12/ Abo R. MR 38 47' ' / 10/16 16 MR 38 47' ' /11/ A Abo R. Trib. 1 MR 38 47' ' /11/ B Abo R. Trib. 2 MR 38 47' ' /1 1/ C Abo R;:- WF - 1 km HR 38 47' ' /1 1/ Burara R. T ' oroy /10/ Wesha R. T 38 39' oro5 ' /10/ Chaho R::- :- MR ' ' /10/29 21 MR ' ' /12/ Roba R. MR ' 09 15' /10/ Etoto sr. 1 rt ' ' /1 1/ Etoto sr. 2 ere ' ' /11/ Kehee R. Headw. MR 38 45' ' /1 1/ Dima R. Trib. MR ' 09 07' /11/ Werka R. Trib. T ' oro4.5 ' /12/ Werka R. T ' oro4.5' /12/10 20 Mojo R. T ' 08 47' /12/ Sekord R. HR 38 59' 09 07' /12/28 14 Sekord R. Pool HR 38 59' 09 07' /02/16 17 Sekord R. Below. HR 38 59' 09 07' /02/ Mewkerya R. MR 39 40' ' /01/ Mewkerya R. Trib. MR ' ' /01/ Kosso R. MR 39 39' ' /0 1/ Zebaba R. MR 39 38' ' /01/12 Daka R. MR 39 46' oros' /01/ Daka R. Cofl. 21 MR ' oro7 ' /01/ Weyb R. :- :- :- MR 39 46' oro7 ' /01/ Shaiha R. HR 39 58' or1 o' /01/20 23 Mi a R. Trib. ER 39 56' ' /01/ Miha R. ER 39 56' ' /01/ Tegoa R. MR ' 06 58' /01/22 26 Hako R. Headw. ER 39 38' oro3 ' /01/ Ashilo R. HR 39 30' oro2 ' /01/ Ashilo R. Trib. HR ' oro2 ' /01/ Wahekora R. HR ' oroo' /01/ Wabe Shebele R. HR ' oro1 ' /0 1/ Akaki R. HR 38 47' ' /02/ Jila R. MR ' ' /02/16 Hora Kelo R. T 38 40' or42 ' /02/ Bulbula R. T ' or 51' /02/ Awash R. HR 38 25' 08 51' /03/08 36 Aosto R. T 38 25' ' /10/ Kola R. T ' 06 38' /10/ Bilate R. EP ' or1 7' /10/ Awash R. EP ' 09 14' /1 1/ ER = Eirhithral rr = rrig ere = below Etoto Mariam Churh MR = Metarhithral rib = ributary rt = ear radio tower HR = Hyorhithral Headw = Headwater EP = Eiotamal T = Trasitioal Cofl = Cofluee WF = Waterfall - This statio ad a umber of other statios dowstream (there alled Kebee R.) were thoroughly samted durig wet ad dry seasos of 1984 ad These samlig statios extede ito the olluted setio ruig through Addis Ababa. * :- Samled o umerous oasios util Ja :- :- :- Also selled Weyib, Web or Ueb.

7 Bethi faua of Ethioia moutai streams ad rivers 7 Faual samles Had ets, eah with a metal rig, aroximate size 25 em, ad a Nitex bag, 0.20 mm mesh, were used. Stoy rus were samled by holdig the had et dowstream from a ath of stoes whih the were tured over by had or foot ad rubbed vigorously. Larger aimals were olleted by laig the et samle diretly ito a white eamel tray ad ikig out seimes for reservatio ad further examiatio i the laboratory. Idividual stoes were also laed i trays ad examied. For smaller seimes, the et samles were trasferred ito lasti bags or jars of water to whih formali was added to make a solutio of aroximately 5% formaldehyde. I the laboratory, the samles were washed i a et of the same mesh ad sorted uder a dissetig mirosoe. Seimes requirig further study were mouted i Caada balsam or Euaral ad examied uder a omoud mirosoe. Bakwaters ad margial vegetatio were samled by vigorous swees of the hadet ad the samles treated i the same way as those from the stoy rus. Results I. Physial ad hemial fators Water temeratures (Table 1) Most temeratures reorded i the moutai regio were betwee 4.5 C ad 20 C. Lower temeratures were foud at the higher altitudes, e. g. ET 19, 20, 21, 24 ad 26. Higher temeratures, ragig u to 25 C, were reorded from rivers o the floor of the Rift Valley, e. g. ET 32, 34, 35, 38 ad 39. Water hemistry (Table 2) Ioi oetratios were low i moutai streams ad rivers. I some ases the ommoly observed atioi order was: Ca> Mg> Na> K, but at ET 4, 30 ad 19, Na>Ca. This same order beomes muh more exaggerated i the Ethioia Rift Valley lakes (TALLING & TALLING 1965, HARRISON 1987). Field H readigs were take at ET 2 ad 5; both were 6.8. Table 2. Chemial aalysis of Ethioia River Water. Statio Abo Chaho Wesha Wabe Weyb Daka Shebele ET:!I: Altitude m I mg r-t Ca Mi Na K CI Si HC03 so - ot measured

8 - 8 A.D. HARRISON ad H. B. N. HYNES II. The faua 1. Faua of the soure zoe The high lateau of the Bale Moutais, ear Mt. Goba, was visited durig the dry seaso, Jauary The lateau lies mostly above 4000 m ad otais a umber of small lakes ad ods, may ermaet. All streams o the lateau were dry at the time ad it aeared that o ermaet stream faua existed. I the moutais above Addis Ababa (ET 7) a marshy stream ad srig were samled i a soure zoe at 3000 m. The faua osisted maily of: Dugesia GIRARD; Cetrotilum s. A (see setio 7. Taxoomy), Cloeo s.; Caeis STEVENS, ad Afroaeis s.; Heterotera, iludig Gerris FABRICIUS, Miroeta KrRKALDY, Sigara FABRICIUS ad Aisos SPINOLA; Dytisidae iludig Hydroglyhus fufai (OMER-COOPER) (see BrsTROM 1986), Herohydrus iqu atus (BoHEMAN) ad Agabus s.; Hydrohilidae iludig Paraymus motiola WooLDRIDGE ad Laobius sotti D'ORCHYMONT; hydraeid beetles; a seies of Aoheles MErGEN; hiroomids, iludig Paratriholadius mias KIEFER, Rheoriotous aesis KIEFER, Tveteia alveses (EDWARDS), Parametrioemus s. ad Rheotaytarsus (motaus grou). 2. Faua of stoy rus ad torrets (Tables 3 ad 4) The streams of the moutai regio (rhithral) have a bethi ommuity (Table 3) osistig maily of: Dugesia s.; Baetis harrisoi BARNARD, Cetrotilum sudafriaum LESTAGE, Pseudoloeo maulosum CRAss; Caeis s., Afroaeis s.; Afroorus "erigueyi" EsBEN-PETERSEN; seies of Neoerla NEED HAM; Chimarra s., Hydrosyhe s., Cheumatosyhe s. iludig oe seies of the C.afra (MosELY) tye; the elmids Mirodiodes troilus HINTON ad Steelmis sotti HINTON, ad larvae of the Pseheid Eubriaax KrESENWETTER; Simulium arabium CROSSKEY & BurrGER, S. detulosum, S. medusaeforme; the Chiroomidae show i Table 4. The ymhs of Aesha FABRICIUS are a ommo redator. The letohlebiids, Choroteres EATON (Euthraulus BARNARD) s. were foud ommoly i the rivers of the moutais to the south-east of the Rift Valley but ot i the moutais of the orth-west side. Table 3 arrages the statios aordig to altitude ad some altitudial zoatio is aaret. Those orgaisms harateristi of the uer zoes ( m) are: Cetrotilum varium CRAss (shar sies) (see Setio 7.3.1), Afrourus "harrisoi" BARNARD, Cheumatosyhe s. G, Statobia s., Ugadatrihia s., Hydraeidae, a seies of Perioma WALKER ad Tveteia s. (Table 4, ad Setio ). Orgaisms harateristi of the lower moutai zoe ( m) are: Cetrotilum varium (blut sies); Nauoris obsuratus MoNTAN DON; Cheumatosyhe s. D; some seies of Helmidae (adult tyes 2, 3, 5, ad 7; larval tyes 4, 7 ad 9); a seies of Atoha OsTEN SACHEN, ad Simulium aloki PoMEROY.

9 Bethi faua of Ethioia moutai streams ad rivers 9 Uer zoe statios (ET 15, 17 ad 18: Table 3, Col. 2), i the moutais just orth of Debre Birha ( m), lie i a regio where the soil ad bed erosio is artiularly severe. These were samled durig the dry seaso whe silt was ot movig ad the beds were temorarily stable. Nevertheless, the umber of seies reset i these three statios (21) is osiderably less tha that i the more ormal statios (52), (Table 3, Col. 1), B. harrisoi was ommo or abudat at all three statios ad Simulium arabium ad S. detulosum aeared to be thrivig; some otherwise ommo seies ad most rarer seies were abset (Dugesia s., Cetrotilum varium "shar sies", Pseudoloeo maulosum, Afrourus "erigueyi' Neoerla s., all seies of Cheumatosyhe, all Elmidae ad some Chiroomidae (Table 4)). At about 1900 m there is a marked hage i the stoy ru ommuity. Dugesia s. beomes less ommo, umbers of Baetis harrisoi ad Cetrotilum sudafriaum fall off ad B. glauus aears. Other seies whih disaear or beome rare are: Pseudoloeo s. A, C. varium (shar sies), Afroaeis s., Cheumatosyhe s. E ad G, hydrotilid addis, Simulium arabium, S. shoae, S. detulosum, S. medusaeforme, ad the hiroomids Criotous (M.) harrisoi ad Rheotaytarsus s. (blak head). Seies aearig i this zoe are Baetis glauus AGNEW, Cetrotiloides LESTAGE, Elassoeuria EATON, Triorythus EATON, Ehemerythus GILLIES, Dieromyzo DEMOULIN, Cheumatosyhe s. H, ad some Elmidae. Below 1900 m, i the foothill zoe (Table 3, Col. 4), it is lear that the moutai ommuity desribed i the first aragrah of this setio is beig relaed by aother. This is ot so obvious i those ases where the rivers ru straight out of the high moutais so that water temeratures are ket low ad elemets of the moutai ommuity are ommo i the drift, seially i the raiy seaso (ET 3, 4, 11, 12, 13, 36 ad 37). However, ET 38 o the Bilate River, o the Rift Valley floor at 1700 m, is searated from the moutai regio by a log series of aal-like strethes ad marshes; the stoy ru was at the begiig of a zoe of rejuveatio. Here, B. harrisoi ad most of the rest of the moutai stream ommuity were abset ad were relaed by suh seies as Baetis glauus, other seies of Baetis, Cetrotiloides s., Elassoeuria s., Ehoro WILLIAMSON, Triorythus s. Cheumatosyhe s. H, ad Simulium bovis. The hiroomids were muh the same as those of the moutai zoe ad o obviously ew seies aeared. ET 39, o the Awash River at 750 m, was a stoy ru artifiially reated by a irrigatio barrage. The river here was well ito the eiotamo ad far from the moutais; the faua was similar to that at ET 38, with B. harrisoi omletely relaed by B. glauus, Cetrotiloides s. ad some other baetids. No Elassoeuria s. were foud but Letohlebiid tye A was abudat (Setio ). There was also a seies of the large amhibious Elmid Potamodytes GROUVELLE (Setio 7.7.2). A umber of seies from the lower moutai zoes were also

10 Table 3. Faua of stoy rus, showig omarative desity : ad eretage(%) statios where foud. - 0 Altitude rage m Statios 2, 2A, B, 5, 15, 17, 18 1, 1A, 2C, 14, 3, 4, 11, 12, 9, 19, 20, 21, 22, 27, 28, 29, 13, 36, 37, 38 24, 25 30, 31, 35 Bed ad lad erosio oe or,.- severe moderate moderate mild -severe -severe :: % ::- % ::. %,, % Plaariidae: > Dugesia s. f-a 100 -C 72 -C 62 tl Aeshidae: Aesha s. -f 60 -f :: Baetidae: V> 0 Baetis harrisoi BARNARD C-A 100 C-A 100 C-A 100 -A 75 z Baetis glauus AGNEW -C 25 ::l Cetrotilum sudafriaum LESTAGE -C 90 -f 33 -A 64 -C so ::r: C. varium (blut sies) -C -f so t::p C. varium (shar sies) f-c 100 -f 18 z C. s. A -A 70 -A 45 Pseudoloeo maulosum CRAss -A 60 -C 73 -f 63 ::r: Pseudoloeo s. A -f 40 -C 36 trl V> Cetrotiloides s Oligoeuriidae: Elassoeuria s. -C 13 Caeidae: Caeis s. -f 90 -A 66 -A 100 f-c 100 Afroaeis s. -C 20 -C 33 -C 45 Caeodes s. -f 25 T riorythidae: Triorythus s. -C Ehemerythus s Dieromyzo s so ::r: > 0..

11 Letohlebiidae: Choroteres (Euthraulus) s. -C 40 -A 45 -f 25 Hetageiidae: Afrourus "harrisoi" BARNARD -C 40 A. "erigueyi'' EssEN-PETERSEN -C 80 -A 82 -A 75 Perlidae: Neoerla s. -C 60 -f 54 -C 88 Nauoridae: Nauoris obsuratus MoNTANDON -f t;j::j ::s... Philootamidae: ::r Chimarra s. -A ;:; -f 27 -A 38 H ydrosyhidae: ::s Hydrosyhe s. -C C I'> 0 Cheumatosyhe afra (MosELY) -f 50 -f 27 tt1 C. thomasetti-tye -C 36 -f ::r C. s. B -C 50 -f 45 -C 25 s "0 C. s. F -C 70 -C 33 -C 36 -C 63.; ::s C. s. G -C C. s. H 38 0 C. s. I -C 9 ::s... I'> Leidostomatidae: s Goerodes s. -f 60 -C ' H ydrotilidae: I'> Hydrotilid s. A f 9 3 I'> Orthotrihia s. - -f 36 ::s 0.. Statobia s. -f 10.., Dytisidae: :;:-.., Hydroglyhus fufai (OMER-COOPER) -f 40 9 Potomoetes abyssiius (SHARP) -f Herohydrus iguiatus (BOHEMAN) Agabus s Hydrohilidae: Paraymus motiola WooLDRIDGE -f Laobius sotti D'ORCHYMONT -f

12 .. Ta bte 3 (otiued 1) - 1'..:. Altitude rage m Statios 2, 2A, B, 5, 15, 17, 18 1, 1A, 2C, 14, 3, 4, 11, 12, 9, 19, 20, 21, 22, 27, 28, 29, 13, 36, 37, 38 24,25 30, 31, 35 Bed ad lad erosio oe or severe moderate moderate mild -severe -severe ::- % ::- % :: % ::- 0/o Hydraeidae: adults -f > Helodidae: larvae -C Pseheidae: :: > Eubriaax s f 27 -f 38 Elmidae: Adults: 0 z Steelmis sotti HINTON -f Mirodiodes troilus HINTON -f 30 -f Tye 2 -f - :s Tye 3 -f 9-13 Tye 5-9 Tye Larvae: Tye 1 -f 50 -f 27 -f 13 Tye 2 -f 40 -f 36 - Tye 3-13 Tye 4 -f 18 Tye 5-13 Tye 6-13 Tye Tye 8-13 Tye t:l $>) 0... :: to z ::r: 1!1

13 l Tiulidae: Tiula s C 36 -f 25 Limohila s. - Atoha s. -f f Psyhodidae: Perioma s. -f 30 Simuliidae: Simulium arabium CROSSKEY & BurG. -A 90 -C 100 -C S. detulosum RouBAUD -A 80 -A 100 -A S. shoae GRENIER & OvAZZA -f 66 -A S. medusaeforme PoMEROY -C 40 -C S. aloki PoMEROY - S. bovis DE MEILLON S. vorax PoMEROY Ceratoogoidae: Bezzia-tye larvae A tj::j ::;).. ::r r;.. : ::;) 0.. tli.. ::r a 0 iii' ::;) Musidae: Limohora s. -f 50 -f 66 -C H ydraaria: f : Desities : A= abudat; C = ommo; f = few; = reset; = ot foud i samle : ::;).. 5'...., 3 (I) ::;) 0...., <".., (I) - VJ

14 .. Table 4. Chiroomidae from stoy rus i Ethioia rivers ; omarative desity': ad eretage statios (%) where foud. Altitude rage m Statios 2, 2A, B, 5, 15, 17, 18. 1, 1A, 2C, 3, 4, 11, 12, 21, 24, , 22, 27, 13, 36, 37, 28, 29, 30, , 35. Soil ad bed erosio oe or severe moderate moderate mild to severe to severe :: % :: % ::. % ::. % -- Tayodiae: > Cohoeloia trifasia FREEMAN f 50 tj Nilotayus s. 13 ::r: > Larsia s. f 20 f 18 f 13 ::0 ::0 Parameria s. f 10 f 9 0 Ortholadiiae: z I'> Coryoeura s. 50 f 33 f :l 0.. Criotous bizoatus FREEMAN ::r: C. flavozoatus FREEMAN 10 A 9 tj:j C. (Marius) harrisoi FREEMAN z Cardioladius oliffi FREEMAN f Tveteia alveses (EDWARDS) 50 ::r: Parametrioemus sotti FREEMAN 70 f 100 f t!1 Paratriholadius mias KIEFFER f Rheoriotous aesis FREEMAN 60 f 18 f 38 Thieemaiella s. A 60 f 33 f 25 Chiroomiae: Polyedilum s. tye Polyedilum s. tye Rheotaytarsus f. motaus LEHMANN A f 100 A 45 f 27 Rheotaytarsus f. fusus FREEMAN A 10 Rheotaytarsus s. blak h. 40 f 66 f 66 >: Desities: A= abudat; C = ommo; f = few; = reset; = oe reset i samles

15 Bethi faua of Ethioia moutai streams ad rivers 15 reset: Cetrotilum varium (blut sies), Afrourus ''erigueyi", Triorythus s. ad Cheumatosyhe tye D (? thomasseti) ad the hiroomids. The oly additioal hiroomid was a seies of Nilotayus KIEFFER. 3. Faua of bakwaters ad quiet sots Although we devoted less attetio to traquil waters tha to stoy rus, we made some observatios o the faua of suh laes: Amog the eusto, Gerris gobaa POISSON ourred o several ools ear Addis Ababa, from m, but was ot see o the souther side of the Rift Valley. This distributio was also foud i 1944 (HYNES 1955). I 1944 both Rhagovelia hyesi POISSON ad Erymetra atalesis (DISTANT) were ommo o streams o both sides of the Rift Valley, but durig the reset study the first was ot see at all, ad the latter was foud oly at ET 10. Other water striders, however, remaied reset o lower, larger water ourses, suh as ET 33, 34 ad 39. These iluded Gerris swakoesis (STAL), Hyesioella aethioia POissoN (oly ET 33 ad 34), Rhagovelia igrias (BuRMEISTER) ad Mesovelia vittigera HoRvATH. BRINCK (1955), reorted oe seies of Gyrius, three of Auloogyrus ad three of Dieutus from Ethioia, ad he also reorted (1956) five seies of the diffiult geus Oretogyrus from the same area. Of these we foud Auloogyrus abyssiius REGIMBART ommoly o streams betwee 2950 ad 1900 m, ad Dieutus godarius REICHE fairly frequetly o slower reahes from 2850 to 2450 m. Less ommo were: a seies of Oretogyrus REGIMBART (Lobogyrus BRINCK) foud o two streams at 2600 ad 1900 m, ad A. ater BRINCK, foud i small umbers o three small streams betwee 2900 ad 2450 m. Some seimes of Lobogyrus ad a few of A. abyssiius were ifeted with fugi of the Laboulbeiales (TAVORES 1979). Oly two tyes of gyriid larvae were foud, distiguished by the thikess of their gill filamets; they ourred from m, sometimes together. Dixiid ad aohelie larvae were also take i several high altitude loalities. I the water, bugs of the seies Laotrehes brahialis GERSTACKER were foud i srig ools, ET 7 ad 8. Miroeta dimidiata POISSON was ommo i may loalities from 3000 m dow, ad was relaed by M. sutellaris STAL at ET 33 ad 34, whih both drai Rift Valley lakes where the seies is ommo (HYNES 1955). At those low-altitude loalities the hemitera faua of quiet reahes was erihed by the additio of Plea ullula STAL ad Shaerodema grassei POissoN; ad members of the geera Sigara, Nyhia STAL ad Aisos ourred soradially at several statios. Mayflies of the geus Cloeo ourred i several loalities u to 3000 m (some of the ymhs resemblig C. rassi AGNEW). I streams above 2500 m, quiet waters were ihabited by Cetrotilum s. A, whih was relaed below 2000 m

16 16 A. D. HARRISON ad H. B. N. HYNES by Baetis bel/us BARNARD. Zygotera larvae were also widesread, but Gomhidae were foud oly at lower altitudes, below 1900 m. Sails were sare, aart from Aylidae of swift water (maily Aylus fluviatilis MuLLER), but Physa auta DRAPARNAUD was ommo i the Akaki River, ET 31. Members of the geera Bulius MuLLER, Lymaea LAMARCK ad Afrogyrus BROWN & MANDAHL-BARTH, as well as Melaoides tuberulata (MuLLER) were olleted i the Bulbula River, ET Faua of moss i torrets (ET 2, 2500 m; ET 19, 3100 m) The ommuities were similar to those of the earby stoy rus, but some seies were far more abudat ad others were oly foud i this biotoe. At the waterfall at ET 2 harateristi seies were: Hydrotilid s. A (Setio 7.6.3), Perioma s. (Psyhodidae) ad a larva resemblig Limohora RoBINEAU DESVOIDY but learly differet from the ommo oe i the rus. Stoy ru seies artiularly abudat were Cardioladius oliffi FREEMAN ad Tveteia alveses. At ET 19 there was a luxuriat growth of moss ad Lemaea s. whih suorted a very dese faua. The oly harateristi seies was hydrotilid s. A but the followig stoy ru forms were artiularly abudat: Cetrotilum sudafriaum, Chimarra s., elmid larvae ad adults, Cohoeloia s., Thieemaiella s., Co ryoeura s., Rheoriotous s., Tveteia alveses, Criotous (M.) s., Rheotaytarsus s. f. fusus ad Rheotaytarsus s.. motaus. 5. Faua of margial vegetatio Margial vegetatio was samled at ET 5, 12, 14, 30, 37 ad 39 ( m). Orgaisms also ommo i earby stoy rus were: Neoerla s., B. harrisoi, C. varium, Trio rythus s., Caeis s. Choroteres (E.) s., Cheumatosyhe s. ad Elmidae. I additio, there was aother grou seifi to this habitat: Baetis bellus (overig the whole altitude rage, ET 5, 37 ad 39), Baetis latus AGNEW (ET 12), Cetrotilum exisum BARNARD (ET 5), Pseudoloeo viosum BARNARD (ET 30), ymhs of Pseudagrio SELYS (ET 37, 39), libellulid ymhs (ET 30), Miroeta dimidiata PoiSSON (ET 30, 37), dytisid, hydohilid ad hydraeid adults (ET 5), Dixidae (ET 5), ad addis Mystaides s. (ET 14) ad Athrisodes s. (ET 37). 6. Faua of slow-flo\v ig streams Two slow-flowig streams o the floor uf the Rift Valley were samled: First, the Bulbula River (ET 34) whih flows out of Lake Ziway. A waterfall ad margial vegetatio were samled. Baetis harrisoi was foud o the waterfall as well as Baetis s. B, Amhisyhe s. (Setio 7.6.2), ad Orthotrihia s. The ommuity i margial vegetatio osisted maily of Cloeo f. rassi, Pseud-

17 Bethi faua of Ethioia moutai streams ad rivers 17 agrio s. ad libellulid larvae, a seies of Triaeodes MLACHLAN, larvae of Eohrus THOMSON, ad a assemblage of hiroomids harateristi of ods: Proladius brevietiolatus, Chiroomus formosieis KIEFFER, Eifeldia disarilis (GOETGHEBUER) ad Dirotedies 14-utatus (GoETGHEBUER). There was oe ommo rosobrah, Melaoides tuberulata, ad oe ulmoate, Bulius f. truatus (AuDOUIN). Seod, the Hora Kela R., the outflow of Lake Lagao ito Lake Abijata (ET 33). Aart from beig slow-flowig this stream was of artiular iterest as Lake Lagao water is fairly highly mieralized (odutivity 1600 S m-1; riial ios i mg 1-1 : Ca2+ 4.7, Mg2+ 2.5, Na+ 350, K+ 23, HCO - 766, Cl- 18, so ; the Na oetratio was muh higher tha the Ca). The faual ommuity osisted of: Cloeo f. rassi, Caeis s.; Pseudagrio s., libellulid larvae, Paragomhus s. (robably from sad, but may were i the margial vegetatio ready to emerge); Rhagovelia iferalis afriaa LuNDBLAD; Eomus robably E. thomasetti MosELY; a seies of Mystaides BERTHOLD (a first reord of this holarti geus from Afria), a seies of Oeetis MLACHLAN, larvae similar to Triaeodes MLACHLAN; Simulium adersi PoMEROY; the hiroomids Criotous (C.) sottae, Nilodorum brevibua KIEFFER, Dirotedies 14-utatus ad Dirotedies s. No molluss were foud. The yriodot miow, Aloheilihthys atiorii (VINCIGUERRA) was ommo. 7. Faual idetifiatios ad seies distributio i go haeta - The Tubifiid Bothrioeurum vejdovskyaum SToLe was foud at ET 19, 24 ad 25; this seies was also foud o Mt. Elgo (WILLIAMS & HYNES 1971). Aulodrilus igueti KowALEWSKI was foud at ET 34. Small Naididae ourred ifrequetly: Pristie/fa jekiae (STEPHENSON) (ET 17, 25, 32); Pristia robosidea BEDDARD (ET 18); Dero D.? obtusa D'UDEKEM (ET 31). r 7.2 Crabs Crabs of the geus Potamoautes s. were foud oly i the streams i the moutais to the south-east of the Rift Valley. Noe was foud i the orth-wester moutais i site of extesive searh, although oe of the authors (HBNH) had foud some i the T'afo River (west of ET 14) i Our olletio otais two seies that Mr. T. WILLIAMS iforms us seem to be ew. 7.3 E h em e r ot era Baetidae These were all idetified from their ymhs. Oe of the authors (ADH) is very familiar with the souther Afria Baetidae from the Cae to the Zambezi, iludig those from may tye loalities; the other author (HBNH) is familiar 2 Arhiv f. Hydrobiologie, Sul.-Bd. 8 1

18 18 A.D. HARRISON ad H. B. N. HYNES with Baetidae from the East Afria moutais. Most of the Ethioia seimes fit i losely with those of seies from souther Afria ad have bee assiged to them. Baetis harrisoi ymhs ad adults orresoded losely to those desribed by BARNARD (1932), ad we have similar ymhs from Mt. Elgo. B. bellus ymhs were similar to those desribed by BARNARD (1932) i all resets. Nymhs of B.glauus ad B. latus losely resembled those desribed by AGNEW (1961). Pseudoloeo maulosum ymhs were first desribed by CRAss (1947), from the Yarrow stream, Natal; he suseted that they were of this seies but was ot able to orrelate them himself. Oe of us (ADH) was able to orrelate ymhs from seimes olleted ear Harare, Zimbabwe, ad the idetifiatios were ofirmed by CRAss. The ymhs olleted i Ethioia varied greatly i size ad olouratio. Those from higher altitudes were larger ad darker ad showed little sig of the light dorsal abdomial strie itured by CRAss (1947), but those from lower altitudes were smaller ad had a lear strie; this was eseially the ase with those from ET 38. It was suseted that there was more tha oe seies ivolved, but itermediate forms were foud. Cetrotilum s.: C.sudafriaum ymhs losely resembled those desribed by BARNARD (1932) ad we have similar ymhs from Mt. Elgo. This seies may be very lose to C. motaum KIMMINS, the ymhs of whih have yet to be desribed. There were two tyes of ymh similar to those of C. varium (CRAss, 1947): the first tye had a sigle row of shar dorsal abdomial sies ad resembled those olleted by ADH i Zimbabwe ad i arts of South Afria. The idetifiatio of these was ofirmed by CRAss (ersoal ommuiatio) who stated that his figure was faulty i that it should have show the abdomial sies. The moutharts of the Ethioia seimes resembled those figured by CRAss. The seod tye of ymh, more tyial of the lower zoes (Table 3), had muh bluter abdomial sies ad aears to be a ew seies losely related to varium. These two ymhal tyes orresod to s. C ad s. A of ''Aetrella" of HYNES & WILLIAMS (1962) o Mt. Elgo. Cetrotilum s. A is a ymh with log oval gills ot resemblig ay other seies desribed from Afria ad aears to be ew. It was foud i slow urret areas o both sides of the Rift Valley ad seems to be idigeous to Ethioia. Pseudoloeo s. A ymhs aear to be the same as those reorted as P. s. ov. from the Chimaimai Moutais, easter Zimbabwe (HARRISON 1965b). The Chimaimai ymhs were foud i waterfalls ad fast torrets, ad subimagos were foud emergig i quiet sots earby; these develoed ito imagos whih keyed out to Pseudoloeo. Nymhs ad adults were deosited i the British Museum (Natural History) (Catalogue Nos. SRE. 3A, 3B ad 3C, 14 May, 1963). HBNH olleted similar ymhs ("Aetrella s. B") o Mt. Elgo (WILLIAMS & HYNES 1971) ad there is a hotograh of a similar ymh from Mt. Keya i VAN SoMEREN (1950).

19 Bethi faua of Ethioia moutai streams ad rivers Caeidae There were robably several seies of Cae is as well as ymhs of Caeodes (DEMOULIN 1970). Afro ae is ymhs resembled those figured for A. major GILLIES, a seies desribed from Ethioia (GILLIES 1982) Triorythidae Most ymhs of Tr io rythus aeared to belog to the same seies but these seemed to be aomaied by a larger seies i the Wabe Shebele R. (ET 30) Letohlebiidae Nymhs of Chorote res (Euthra ulus) s. were foud i the moutais to the south-east of the Rift Valley but ot i those to the orth-west. Nymhs of Letohlebiid tye A were foud at ET 39 at 750 m. Dr. W. L. PETERS (rivate ommuiatio) iforms us that these ymhs losely resemble those of Chorote res (Euthra ulus) i the struture of the thorax ad abdome, iludig the gills, but that the moutharts are highly modified for filter feedig. The seies is loser to Chorote rides tha to ay other geus, but does ot fit ito this geus as urretly defied. Chorote rides has bee foud so far i Asia ad Madagasar Hetageiidae The ymhs we all Afro urus "harr iso i" ad A. ''er igue yi" were similar to those i BARNARD (1932) but we realize that they ould rereset seies grous. A. ulher ULMER ould be the adult of our A. "er igue yi" ymhs, judgig from the loatios where it was olleted (ULMER 1930). We have similar ymhs from Mt. Elgo. 7.4 He t e r ot era Na uor is obs urat us was the setes olleted also by HYNES (1955) ad idetified by R. PoissoN. 7.5 L e i do te r a Pyralidae A few larvae were olleted from margial vegetatio, ad a few larvae losely similar to the Hydroamidae reorted by WILLIAMS & HYNES (1971) from several lower-altitude loalities o Mt. Elgo, were foud i the Weyb River (ET 21). 7.6 Tr i ho t era Philootamidae KIMMINS (1963) reorts two seies of Ch imarra, the most widesread beig C. abyss i ia BANKS. Dr. K. M. F. Sorr says that males we olleted at ET 20 were of a ew seies (rivate ommuiatio).

20 20 A. D. HARRISON ad H. B. N. HYNES Hydrosyhidae KIMMINS (1963), who worked with a olletio of adults, reorts two seies of Hydrosyhe from Ethioia; the most widesread is Hy drosyhe abyssiia KIMMINS. He reorts seve seies of Cheumatosyhe ; he had umerous seimes of C. afra ad C. ubi la KIMMINS, whih he says is very similar to C. thomasseti (ULMER). He reorts three seies of Amhisyhe. Dr. K. M. F. Sorr says that our larvae resembles A. seega lesis (BRAUER), (see also Sorr 1983) Hydrotilidae Dr. K. M. F. Sorr iforms us (rivate ommuiatio) that the larvae we have alled "Hydrotilid s. A", a very dark larva i algal ases, aot be laed ito a kow geus; ossible adidates are Dhatrihia MosELY ad Madio xyethira SHMID, but these larvae ould belog to yet aother geus. A mature male ua of Orthotrihia we olleted at ET 30 was 0. strae lei jacquemart. 7.7 C o 1 eo te r a Dytisidae The seies of Agabus aears to be ew Elmidae We foud the two seies desribed by HINTON (1940), Mirodiodes troi lus ad Stee lmis sotti. We also foud a seies of Potamodytes i the lower eiotamal of the Awash River (ET 39); BoLLOW (1939) reorts P. zavattarii from Ethioia ad Somalia. The geus has bee foud i the middle ad lower eiotamal i West Afria (FoRGE 1981), i Zimbabwe (ADH reords) ad o Mt. Keya (HBNH reords) Pseheidae HINTON (1940) also reorts larval Eubr iaax from Ethioia, from a highaltitude stoy ru. 7.8 Ditera Simuliidae Few Simu lium seies ourred i the high streams, ad our material available for seifi idetifiatio was mostly ual. The ommoest seies were S. arabium CRoSSKEY & BuTIIGER, a member of the igritarse omlex (FAIN & DuJARDIN 1983), ad S. detu losum RouBAUD, both of whih ourred u to 3500 m. At 2850 m these were joied by S. shoae GRENIER & OvAZZA, a seies that was origially desribed as a form of S. detu losum RouBAUD, but whih seems to be distit ad idigeous to Ethioia. At some statios it relaed S. detu lo sum, ad either was foud at lower altitudes.

21 Bethi faua of Ethioia moutai streams ad rivers 21 S. medusaeforme form hargreavesi GIBBINS, as illustrated by FREEMAN & DE MEILLON (1953), was foud i sattered loalities from m, ad a few seimes of S. aloki PoMEROY ourred over a somewhat similar altitudial rage. S. rufiore MACQUART was foud i the dry seaso i the Uer Kebee River just after the river eters Addis Ababa. The uae were atyial with resiratory filamets loger ad thier tha usual, similar to those foud i Zimbabwe by ADH i 1966 ad idetified by Dr. R. W. CROSSKEY. Other seies were foud oly at lower altitudes: S. adersi PoMEROY oly i the two lake outlets, ET 33 ad 34; S. vorax PoMEROY oly at ET 4; S. bovis DE MEILLON at ET 37. We searhed for larvae of the horeti seies foud o Mt. Elgo (HYNES, WILLIAMS & KERSHAW 1961) but foud oe; adults of the grou eavei have bee reorded from Ethioia (FAIN & OoMEN 1968) Chiroomidae Tayodiae All adult ad harate adult Cohoeloia over the whole regio were C. trifasia (FREEMAN). The adult Larsia were lose to L. uiformis (GoETGHEBUER) ad the few seimes of Parameria FITTKAU bred out aeared to be of a ew se1es Ortholadiiae Numerous adult Coryoeura dewulfi GoETGHEBUER were aught or bred out over the whole regio; o other seies was foud. Criotous (C.) bizoatus FREEMAN was foud from both sides of the Rift Valley ad may were bred out ad orrelated with larvae from the Abo-Kebee River (ET 2 C ad dowstream); they beame very abudat i setios of the stream reeivig mild ollutio as it flowed through Addis Ababa. At least four other seies ourred; oe resembles C. (C.) jlavozoatus FREEMAN ad the others aear to be ew. Criotous (Marius) harrisoi FREEMAN is widesread ad fits ito the diagosis for the subgeus, Marius (LEHMANN 1981). It has bee orrelated with its larva whih shows distit differees from the larvae of the other subgeera of Criotous. No other seies of the subgeus were foud. Our Ethioia seimes of Tveteia alveses ould ot be searated from other Afria or Holarti T. alveses EDWARDS o aatomial grouds. All adult Parametrioemus aught throughout the regio were P. sotti FREEMAN. Paratriholadius mias KIEFFER ad Rheoriotous aesis KIEFFER were foud throughout the regio ad orrelated with larval seimes from the Abo Kebee River. R. aesis beame very abudat at times i the olluted setio i Addis Ababa. No other seies of these geera were foud. The few adult Thieemaiella atured or bred out were T. lieola.

22 22 A. D. HARRISON ad H. B. N. HYNES Adults of Limohyes atalesis KIEFFER were ommoly etted from bak vegetatio i uer zoes but larvae were rarely foud Chiroomiae Tye 1 larvae of Polyedilum bred out to P. altiola KIEFFER ad Tye 2 to P. wittei FREEMAN. The adults of these ourred over the whole regio. All stages of Chiroomus allaudi were foud i the olluted setio of the Kebee R., below ET 2 C, ad Chiroomus formosieis KIEFFER was abudat i the slow-flowig, but uolluted Bulbula stream (ET 34); they were idetified from harate adults Taytarsii The ommoest larvae of Rheotaytarsus had light yellowish brow heads; those bred out from the Abo-Kebee River were lose to R. motaus LEHMANN. Abudat larvae with brow heads were foud at ET 19; adults atured there resembled R. fusus FREEMAN. A third seies ourred, havig almost blak adults ad larvae with blak heads; this aears to be ew M o 11 u s a The alaearti sail Aylus fluviatilis MuLLER was foud at ET 12, 20, 21, 22, 23 ad 26. It was also foud by BROWN (1980) i this regio. Physa auta DRAPARNAUD was foud at ET 33; BROWN (1980) osiders this to be a North Ameria seies whih has ivaded most of Afria, ossibly through Euroe. He also foud it i the Ethioia Highlads. Seies of Buruia WALKER were foud oasioally (ET 6, 8, 12, 29 ad 30), BROWN (1965) reorts B. affra (KRAuss) from the Ethioia Highlads Pises Numerous small yriid fish were see ofte i the ools of moutai streams ad rivers i the regio. They ivariably roved to be seies of the geus Garra. G. dembeesis (RuPPELL) was foud at ET 2C, 13, 35 ad the Muger River, a tributary of the Awash R. ear ET 35, ad 38; G. quadrimaulata (RiJPPELL) at ET 1 ad 31; Garra f. quadrimaulata at ET 14. The small atfish, Amhilius lamei PIETSCHMANN was olleted i stoy rus at ET 30. Brow ad raibow trout were itrodued ito the Weyb River (ET 21) some years ago ad aear to be thrivig; they are frequetly aught by aglers.

23 Bethi faua of Ethioia moutai streams ad rivers 23 III. Disussio D.t Effets of soil ad bed erosio o Ethioia moutai river faua Soil ad river bed erosio was very severe at ET 15, 16, 17 ad 18 m the moutais to the ortheast of Debre Birha ( m). The moutai sloes were severely deuded of tosoil, ad river baks were ut bak or ollased i may laes. Durig heavy rais, whe the river is i sate, muh mud ad silt is arried by the turbulet water; gravel, stoes ad eve roks are the o the move i the bed. The faual samles were take at least three moths after the last atastrohi sate but the ommuity still had fewer seies tha those of more ormal rivers at the same altitude (21 vs. 52). Absetee seies iluded all trilads (Dugesia s.), Hydrosyhidae ad Elmidae. Some hardier forms, suh as Baetis harrisoi ad Simulium s., survived the raiy seaso ad multilied raidly to beome ommo or abudat durig the dry seaso. A similar situatio is reorted by CHUTIER (1969) from the moutai zoe of the Vaal River, South Afria. He omared badly damaged rivers (his "high level deositig zoe") with more ormal moutai rivers (his "erodig zoe") ad foud that there was redutio i "kids of aimals" as well as i atual umbers durig the dry seaso. Amog his grous redued were the trilads, Hydrosyhidae ad Elmidae. CHuTIER osidered these hages to be aused maily by the istability of the sedimets ad abrasio rather tha by a smotherig effet. I Ethioia rivers most of the faual redutio is the result of abrasio by sad ad the molar effets of rollig stoes ad roks. Nevertheless, large amouts of silt also strogly affet the feedig effiiey of the Hydrosyhidae ad other grous. It is obvious that wide-sread severe soil ad bak erosio ould lead to the extitio of may sesitive aquati seies i the Ethioia moutais. Overgrazig ad other faulty farmig raties are resosible for lad ad river deterioratio i may areas (KuRu 1978). D.2 Pollutio of Ethioia rivers There are few large-sale idustrial lats i Ethioia ad so the serious hemial ad orgai ollutio see i more develoed outries does ot our or is very loalized. Eve i Addis Ababa there is little idustrial waste water ad at reset most domesti wastes are disosed of i seti taks or i oe it or uovered sites, although this will hage i the ear future. The oly seriously olluted river see was the Abo-Kebee flowig from ET 2 through Addis Ababa. Near its exit from the ity it showed the usual sigs of orgai ollutio with the loss of all Trihotera ad may Ehemerotera, although there were usually some to may B. harrisoi still reset. The ommuity

24 24 A. D. HARRISON ad H. B. N. HYNES osisted of tubifiid worms ad more hardy hiroomids suh as Criotous bizoatus, ad other Criotous s., Paratriholadius mias ad Chiroomus al/audi KIEFFER. About km below this, after the river has assed through more built-u regios ad the tow of Akaki (just above ET 31), the faua was almost ormal with may of the usual Ehemerotera, Trihotera ad other stoy ru orgaisms. Notieably, however, here ad also i some of the other degraded streams orth of the Rift Valley, there were dese growths of Cladohora. There were also laes withi Addis Ababa where "sewage fugus", robably Shaerotilus was abudat. A more subtle effet was the aaret disaearae of may water striders, suh as Rhagovelia hyesi ad Eurymetra atalesis, from may streams i the regio. This we ut dow to the extesive use of artifiial detergets by wome washig their lothes i the streams. Powdered detergets used i a basi at streamside have omletely relaed the traditioal "ake of soa o the roks" tehiques of earlier times. D.3 Biogeograhy Biogeograhy of Afrotroial moutai stream faua Afria was origially art of the Jurassi souther otiet of Godwaalad. The souther art of this otiet had a temerate to Atarti limate ad broke u i late Jurassi to Cretaeous times (KING 1978) to form what is ow souther Afria, souther South Ameria, Atartia, Australasia, the Idia subotiet ad other territories. The orther ortio had a subtroial to troial limate ad broke u durig the Cretaeous to form orther South Ameria ad troial ad North Afria ad the Arabia Peisula. The Tethys Sea searated the Afro-Arabia ortio from Eurasia util the sea losed u ad the two lad masses ame ito otat durig the middle Mioee (AxELROD & RAvEN 1978).. With this evet the exhage of faua ad flora bega. EDMUNDS (1975) osiders that a umber of mayfly lieages evolved rimarily i troial Godwaalad, before the Cretaeous breaku. He lists the Astheoodiae (Polymitaridae), Triorythidae, Oligoeuriidae ad Baetidae ad thiks that the North Ameria members of these families derived from the South Ameria oes, ad the Eurasia from the Afria oes. Sorr (1986) sees a similar atter for ertai Trihotera but feels that muh more evidee is eeded to establish the atter. The Afria Simuliidae are iterestig as some have affiities with Holarti ad some with N eotroial seies (CROSSKEY 1969), the latter ould have derived from troial Godwaia seies. It seems, therefore that troial Afria had varied freshwater ommuities osistig of these ad other ivertebrate grous before otat was established with Eurasia.

25 Bethi faua of Ethioia moutai streams ad rivers 25 However, we are iterested i traig the develomet of ool-adated motae ommuities. It seems to be agreed that, rior to the riftig roess whih bega i the Mioee, Afria was mostly a highly-eroded eelai. Nevertheless, AxELROD & RAVEN ( 1978) believe that there is evidee of re-mioee regios of high altitude i the Hogar, Air ad Tibetsi massifs, ow i the Sahara regio, ad the East Afria ad Ethioia wars whih reeded vulaism there. It aears that these wars had summits of 1500 to 1600 m at the lose of the Palaeoee ad this, i ombiatio with wetter ad ooler limates, eabled ertai troial raiforest lat taxa to radiate uwards ito a temerate motae zoe. This zoe would have bee available also for develomet of ool-adated stream ivertebrates, eseially if forests were reset to kee temeratures low. Baetidae ad Hydrosyhidae ould have bee amog the radiatig forms able to move u ito the old, high moutais whe these aeared, leadig to the distributio see today. AxELROD & RAvEN also make the oit that these high altitude regios would allow orth temerate ad south temerate Afria lats ad aimals to exted their rage towards or eve ast the equator. Seies from the ooler souther arts of Afria ould have followed this route ito equatorial regios but HARRISON (1978) oits out that very few of the true old-adated steotherms belogig to the souther Godwaia ommuity aear to have reahed the trois. The develomet of the Afria Rift system, ad its assoiated orogeies, i the late Oligoee ad Mioee dow to the Quarterary, resulted i extesive moutai buildig, with altitudes over 3000 ad 4000 m ad with a umber of glaiated regios. This allowed oloizatio by true old steotherms, but there is o evidee that the origial Afria faua otributed ay of these. The oly aquati grou that seems to be ofied to glaial melt streams i Afria are seies of the hiroomid, Diamesa. WILLASSEN & CRANSTON (1986) osider that Afria seies of this geus ame from stok followig a high altitude disersal route from their Laurasia etre of distributio. They suggest a more or less otiuous, mid-tertiary motae route from the Cauasus ad E ad SE Turkey through the Levat, Dead Sea, Nubia (ad resumably the souther Arabia moutais) ad the Ethioia Highlads. This route ould have bee used also for disersal i both diretios by other motae forms, may ot as old-steothermal as Diamesa. Promiet amog these would have bee the motae Ortholadiiae whih are osidered to have had a orther (Laurasia) origi. The motae forms of the other hiroomid sub-families would have used the same route but the diretio they were takig is ot kow.

26 26 A. D. HARRISON ad H. B. N. HYNES Biogeograhial status of Ethioia mout i river faua This two-way disersal route fially was iterruted by the Red Sea rift whih started i the late Plioee ad still otiues. The Ethioia moutais uderwet may hages from the late Plioee util the reset day; Plioee moutais eroded away to be relaed by Pleistoee moutais. The limate followed that of the rest of East Afria with alterate warm ad dry, ad ool ad wet eriods, sometimes with glaiatio ow lost (LIVINGSTONE 1975). Today the Ethioia Highlads are well searated from the other East Afria moutais by a large ga otaiig the Nile Valley, ad from the moutais of S. Arabia ad the Siai Peisula by the Red Sea ad low-lyig desert outry. I site of the hysial searatio, the Ethioia moutai riverie faua (rhithro) is learly strogly liked to its East Afria ad Souther Afria outerarts. Table 5 shows how may of the ommo geera ad seies (eve though may of these may rereset "seies grous") are foud i moutais all the way from Ethioia to the Cae. I fat, there seems to be a basi ommuity i the stoy rus osistig of suh forms as: Dugesia s., Baetis harrisoi, Cetrotilum sudafriaum, Afro urus s., Choroteres (E.) s., Cheumatosyhe afra, Ch. thomasseti, hiroomids suh as Cohoeloia trifasiata, Criotous flavozoatus, Paratriholadius mias, Rheoriotous aesis, Thieemaiella lieola FREEMAN ad Parametrioemus sotti, ad the Simulium medusaefo rme grou. Some of the seies foud i quieter sots also exted from Ethioia to the Cae, suh a Baetis bellus, Pseudoloeo viosum ad Miroeta dimidiata. Other seies suh as Pseudoloeo s.a, ad some hiroomids ad simuliids are foud oly i the moutais of troial East ad Cetral Afria, or oly as far south as the orther moutais of South Afria. Liks with the faua to the east ad orth are less obvious. BoTOSANEANU (1973) sees a strog oexio betwee the S. Arabia motae Trihotera ad those of Mt. Siai ad of suitable habitats i the Negev ad Dead Sea Deressio. Most of these seem to have Asiati affiities but a few are related to seies foud i Ethioia ad other arts of troial Afria. The latter must have bee reviously disersed alog the Plioee route. Sie the this easter ad orther addis faua seems to have diverged markedly from the Ethioia faua. O the other had some Ethioia aquati orgaisms aear to rereset the southermost eetratio of Palaearti forms. SoTT (1986) lists the addis Mesohylax aethioius MALICKY, ad Mystaides, but these are ot true moutai forms ad she suggests that they ould have ome dow the Nile durig a wetter, ooler eriod. The freshwater sail, Aylus fluviatilis, ommo i streams i the Ethioia Highlads ad SW Arabia is more ool-adated ad might have bee art of a Plioee motae faua ommo to both regios.

27 Bethi faua of Ethioia moutai streams ad rivers 27 Imoverished Ethioia rhithro Although we oted the strog oex10s betwee the Afria moutai ommuities, we also oted that the Ethioia faua seemed to be omaratively imoverished. For istae, the followig aear to be lakig: seies of Adeohlebia ad Prosoistoma reorted from Ugada by WILLIAMS & HYNES (1971) ad from Zaire by KoPELKE (1980, 1981), Baetis ataratae CRAss, Castaohlebia s., Aetrella atalesis CRASS, ad Oligoeuriosis lawreei CRAss (all idetified by CRAss) reorted from Mt. Keya by VAN SoMEREN (1950), ad seies of the addis geera Agaetus, Dolohilodes, Letoema, Pseudoeurelisis, Lye ad Catoxyethira reorted from moutai streams i Zaire by STATZNER (1975) ad jaquemart & STATZNER (1981). KIMMINS (1963) did ot fid these addis seies i his Ethioia olletio either. I additio, BAFORT, GAIN & SILBERSTEIN (1977) reort a umber of seies of Simulium from Mt. Keya ot foud by us i Ethioia. All these either may ot have reahed the regio, or limati rigours durig dry eriods may have led to their extitio. Diamesa robably disaeared with the Ethioia glaiers. Edemis i Ethioia rhithro YALDEN (1983) suggests that the large area of high lad i Ethioia may aout for the high roortio of edemi terrestrial seies. This ertaily seems to be true for terrestrial lats ad aimals. KIMMINS (1963) reorts 24 edemi seies of Trihotera out of a olletio of 53 Ethioia seies he studied; 17 of these edemis ould have ome from moutai streams ad rivers. His results suggest to us that 5 of the 7 seies of Cheumatosyhe we foud were edemi. We also osider that may of our Elmidae will rove to be ew seies ad all seem to be edemi. Certaily oe of them is the same as seies olleted by WILLIAMS & HYNES (1971) o Mt. Elgo. Nevertheless, there seems to be little edemiity i the Ehemerotera ad Chiroomiae; we foud oly oe ew baetid (Cetrotilum s. A), or two if the uer zoe form of Pseudoloeo maulosum roves to be ew. There are two or three aaretly ew seies of hiroomids whih ould be edemi. Edemi simuliids have bee reorted by UEMOTO, OGATA & MEBRAHTU (1977), but we did ot fid ay of their seies. BRINCK (1956) reorts three edemi gyriids, ad our olletio aears to otai a few edemi dytisids as well. D.4 Zoatio Zoatio of Sub-Sahara motae streams ad rivers The logitudial zoatio of souther Afria rivers is disussed by HARRISON (1965 a, 1978). He uses the system roosed by ILLIES & BoTOSANEANU (1963),

28 Table 5. Moutai st ream faua o mmo to Ethioia, ad Easter ad So uthe r Af ri a. N 00 Mouta i Ethiota East Ea ster Tugela R. Great Table Zimbabwe Fa ua Hi gh ads Af ri a Trasvaal Na tal. Berg R. Mt. Baetidae : Baetis harrisoi BARNARD u u u u u UM Baetis glauus A GNEW M - M L L L Cetrotilum sudafriaum LEST AGE u u u u u u Cetrotilum varium CRAss f u u r F - f L sha r sies > Pseudoloeo maulosum CRAss A - M UL M f L tl Pseudoloeo s. A f u u u ::r: Ca eidae : Caeis s. A A A A A A Afroaeis s. u 0 z Caeodes s. T : "" T ri orythidae : Triorythus s. L L L f L ML L ::r: Le tohlebiidae : t:c Choroteres (Euthraulus) s. f U ' ': u :- :--.- u f L M r UM z He tageiidae : ::r: Afrourus "harrisoi" BARNARD f u u u u u UM ttl Afrourus "erigueyi" EssEN-P ETERSEN ML ML M Ph il ootamidae : Chimarra s. u u f u f u f u u H ydrosy h idae : Hy drosyhe s. u UM u M Cheumatosyhe afra (M osely) u u u u Cheumatosyhe thomasseti (ULMER) M M ML L Tayodiae : Cohoeloia trifasia (F REEMAN) u Parameria s. UM ::l A.

29 Table 5 (otiued) l --- Moutai Faua Ethiofaia High ads East Afria Zimbabwe Easter Trasvaal Tugela R. Natal. Great Berg R. Table Mt. -- Ortholadiiae: Coryoeura dewulfi GoETGHEBUER Criotous (C.) bizoatus FREEMAN Criotous (C.) flavozoatus FREEMAN Criotous (M.) harrisoi FREEMAN Cardioladius oliffi FREEMAN Tveteia alveses (EDWARDS) Paratriholadius mias (KIEFFER) Rheoriotous aesis (FREEMAN) Thieemaiella lieola FREEMAN Parametrioemus sotti (FREEMAN) Chiroomiae: Polyedilum altiola KIEFFER Polyedilum dewulfi GoETGHEBUER Rheotaytarsus "guieesis" (KIEFFER) Rheotaytarsus ''fusus" FREEMAN Simuliidae: Simulium medusaeforme PoMEROY = o reord = reset f = few = ommo A = all levels U = u er zoes M = middle zoes T = trasitioal zoes L = lower zoes F = foothills f f f A u u u UM u u u A A A A A u A A U':-,:->:-,:- A >:- Wedo Geet oly >: ' Southeaster Rift moutais oly >:->:- >:- Mt. Elgo ad Mt. Keya >:->: Daka (Weyb trib.) oly u M M M M M u u UM u f A UM M A A u A u t:;x; 0 ::I... ::r ;:; ij' t: ::I Po> 0 -. t't1... ::r o "0 j;; ' ::I 3 0 t: ::I... Po> s... ' 0 Po> 3 Po> ::I 0... ' :;:: 0 ' Soures for iformatio o table: Ethio ia Highlads: Preset survey; KIMMINS 1963 East Afria: VAN SoMEREN 1950; FREEMAN 1955, 1956, 1957, 1958; KIMMINS 1960; WILLIAMS & HYNES 1971 Zimbabwe : HARRISON 1965 a, 1965 b; ad ADH's ow reords Easter Trasvaal : HuGHES 1966 Tugela R., Natal : OLIFF 1960 Great Berg R.: HARRISON & ELLSWORTH 1958; SoTT 1958 Table Mt.: HARRISON & BARNARD 1972 N \0

30 30 A. D. HARRISON ad H. B. N. HYNES who divide rivers ito three mai zoes : first, the kryo, the soure zoe where the water origiates from glaial melt or from srigs or streams i small marshes amog the eaks; seod, the rhithro (moutai torret zoe or erosio zoe) ad, third, the otamo (the foothill ad flood lai zoe, or deositio zoe). They divide the rhithro ad otamo ito three subzoes, desigated ei-, metaad hyo-. However, STEFFAN (1965) oited out that the suffix -o should oly be alied to bioeoses (ommuities) ad that the suffix -al should be used for biotoes (habitat). We take STEFFAN's advie, also followed by BoTOSANEANU (1979), ad use the terms "the rhithral" ad "the otamal" for the habitats. The rhithral is maily torretial, although ools ad bakwaters are reset, temeratures are usually below 20 C at all seasos ad silt loads ad turbidities are very low. The rhithro is old steothermi, mostly torret dwellig ad very sesitive to turbidity ad siltatio. HARRISON (1965 a) oits out that seies livig i bakwaters or quieter sots are artiularly sesitive to high silt otet. I the otamal there are fewer torretial setios, mostly i the eiotamal, ad these disaear evetually as the flood lai is reahed. I a elevated otiet suh as Afria the eiotamal a be very log ad there is ofte rejuveatio as the rivers ru over harder geologial strata. Temeratures are usually above 20 C at some seaso of the year ad turbidities ad silt loads are higher tha i the rhithral; ools are ofte floored with mud. Rhithro, beause of their itolerae of silt, are artiularly sesitive to huma ativities suh as agriulture, iludig grazig, miig ad ostrutio rojets. Muh of the tyial ommuity may disaear with risig silt loads. Potamo are less likely to be affeted by huma ativities exet uder extreme oditios. The rivers ad streams i the Ethioia moutais fall maily ito rhithral ad uer eiotamal ategories. Zoatio i Ethioia motae rivers a. The Kryal (Soure Zoe) The Ethioia moutais are ot high eough to have a ermaet sow lie or glaiatio, although sow falls above 3500 m ad Afro-alie lats are foud at about 4000 m. The high lateau of the Bale Moutais, ear Mt. Goba, was visited durig the dry seaso a auary, 1984) ; there are a umber of small irque lakes ad ods o this lateau but the streams origiatig from them were all dry at that time. It aears that the glaiers o the Ruwezori Moutais ad o Mt. Keya store eough water to kee the streams of the kryal ruig ermaetly ad to sustai the oly true kryo forms kow from Afria, seies of Diamesa. It is ossible that seies of this hiroomid were foud i Ethioia whe glaiers were

31 Bethi faua of Ethioia moutai streams ad rivers 31 reset (WILLASSEN & CRANSTON 1986), but disaeared with them whe the streams beame seasoal. The faua of the streams just below the Mt. Goba lateau is disussed below. The faua foud at ET 7, a lower soure regio at 3000 m, was tyial of a slowflowig stream with othig seial about it. b. The Rhithral (Moutai Torret Zoe) (2000 m ad above) m The highest streams studied were at 3500 m (ET 23, 8 C ad ET 24, 4.5 C), the sub-afro-alie or tree-heath zoe. These ould be lassified as the eirhithral. The bethi ommuity was essetially the same as that of the regio immediately below (Table 3, olum oe); there were o seial forms of eirhithro. It would be iterestig to kow how the life yles of ommo seies were affeted by the low temeratures. The statios listed i Table 3, olum 1 a be lassified as the metarhithral. ET 19 ad 20 were artiularly good as there was very little sig of huma iterferee; ET 2 was also fairly free of siltatio. A few seies whih were ommo at these statios disaeared or beame rare i the ext zoe dowstream (Table 3, olum 3). These were Pseudoloeo s. A, Cetrotilum s. A, Afrourus "harrisoi' Hydrotilid s. A, Statobia s., Ugadatrihia Cetrotilum varium (shar sies), Perioma s. ad Tveteia alveses. Most of the rest of the ommuity osisted of seies tyial of the whole moutai regio. The statios i Table 3, olum three a be lassified as the hyorhithral. The faua is basially the same as that of the zoe above, exet for those few seies that disaear, but there are a umber of additios to the hyorhithro: Cetrotilum varium (blut sies), Cheumatosyhe thomasseti-tye, four additioal elmid adults, three additioal elmid larvae, Simulium shoae, ad S. adersi.. Trasitio Zoe ( m) The statios i Table 3, olum 4, mostly ostitute a trasitioal zoe, as the rivers eter the foothills ad rhithro begis to give way to otamo. Nearly all of the seies harateristi of the rhithral disaear at some stage i the eiotamal, but most are still reset i this trasitio zoe, robably beause may are maitaied by drift from ustream. d. The Potamal ET 38 ad 39 give some idiatio of eiotamo i Ethioia rivers. I this faua the relaemet of Baetis harrisoi by B. glauus ad other baetid seies was omlete ad Triorythus s. had beome the redomiat mayfly, but Elassoeuria s. was also ommo. Both Cheumatosyhe afra-tye larvae, tyial of the uer arts of the rhithral, ad C. thomasseti, tyial of the lower rhithral ad the trasitioal zoe, had disaeared ad were relaed by aother seies.

32 32 A. D. HARRISON ad H. B. N. HYNES This tye of ommuity is also foud i the eiotamal of the Sabi R. m Zimbabwe (ADH, ersoal observatio) ad i the lower Tugela River, Natal (OLIFF 1960) ad i West Afria (DuRAND & LEVEQUE 1981, DEJOUX, ELOUARD, FoRGE & MAsLIN 1983). Summary The major fats emergig from this study are as follows : 1. The faua of high altitude Ethioia streams is tyial of that of ool streams over muh of Afria (. 8-22; 24-26) (Tabs. 3, 4, 5), but it laks several taxa that are reset south of the dry outry of orther Keya (. 27). It also iludes, like the terrestrial flora, a few elemets of aaretly reet Palaearti origi. 2. Although taxoomial kowledge is still saty, it seems that there are few edemi taxa (. 27) i the Ethioia stream faua. Most of our material has bee mathed with seies whih our further south. However, oe Cetrotilum seies seems to be ew; Simulium shoae is robably edemi, as are most of the Elmidae. We have disussed these oits i the light of what is kow about the biogeograhial history of Afria. 3. Reetly the huma oulatio of the Ethioia Highlads has greatly ireased, leadig to severe soil erosio. This erosio has very obvious effets o the streams, beause it elimiates several grous of ivertebrates, severely simlifyig the faua (. 23 ; Tab. 3). 4. Other huma ativities ( ) also seem to elimiate some stream taxa. Gerridae ad Veliidae have beome very sare, ossibly beause of the use of detergets for washig lothes i streams. Crabs seem to have disaeared from the area orth of the Rift Valley, although there are streams that seem to be suitable for them; they were reset i the orther area durig the 1940's. 5. We foud few effets of ollutio (.23-24) exet i Addis Ababa, where tributaries of the Akaki River show severe effets of urba ollutio. We hoe to ublish further o this oit. 6. The kryal (high-altitude old-water zoe) foud o very high moutais further south ( ) seems to be abset from Ethioia, as there is o ermaet sow lie. The rhithral (moutai torret zoe) has a harateristi faua ad exteds dow to about 2000 m (. 31; Tabs. 3, 4). There follows a trasitio zoe extedig dow to about 1650 m (. 31; Tabs. 3, 4), ad below that a otamal (lower zoe) whih otais a faua that is similar to that of muh of Afria ( ). Zusammefassug Die vorliegede Studie hat im wesetlihe folgedes ergebe : 1. Die Faua hohgelegeer Fliisse i Athioie weist die tyishe Merkmale kiihler Fliisse i grobe Teile Afrikas auf (S. 8-22; 24-26; Tab. 3, 4, 5), jedoh fehle ihr mehrere Taxa, die im Siide des Trokelades Nordkeia vorkomme (S. 27). Sie umfabt ebeso wie die terrestrishe Flora eiige Elemete asheied jiigere alaarktishe Ursrugs. 2. Obwohl das taxoomishe Wisse hier oh sarlih ist, sheit es weige edemishe Taxa (S. 27) i der athioishe FluBfaua zu gebe. Der GroBteil useres Materials kote mit de Arte idetifiziert werde, die weiter siidlih vorkomme. Eie Cetrotilum-Art sheit jedoh eu zu sei. Simulium shoae ist wahrsheilih edemish, ebeso wie die meiste der Elmidae. Wir h"abe diese Pukte im Lihte desse diskutiert, was iiber die biogeograhishe Geshihte Afrikas bekat ist.

33 Bethi faua of Ethioia moutai streams ad rivers I letzter Zeit ist die Eiwoherzahl des athioishe Hohlades stark gestiege, was zu shwerwiegeder Bodeerosio gefiihrt hat. Diese Erosio hat sehr offesihtlihe Auswirkuge auf die Fliisse, da sie mehrere Grue vo Ivertebrate elimiiert ud so. die Faua drastish simlifiziert hat (S. 23; Tab. 3). 4. Ebeso sheie adere meshlihe Aktivitate (S ) eiige FluBtaxa zu elimiiere. Gerridae ud Veliidae sid wahrsheilih wege des Gebrauhs vo Washmittel i Fliisse sehr selte geworde. Krebse sheie aus dem Gebiet ordlih des Rift Valley vershwude zu sei, obwohl es dort Fliisse gibt, die ihe giistige Lebesbediguge bote; wahred der 40er Jahre kame sie im ordlihe Gebiet vor. 5. AuBer i Addis Abeba, wo Zufliisse des Akaki-Flusses deutlihe Auswirkuge urbaer Vershmutzug zeigte, kote wir ur weige Azeihe vo Vershmutzug feststelle (S ). Wir hoffe, zu diesem Pukt weitere Veroffetlihuge folge zu lasse. 6. Ei Kryal wie auf de sehr hohe Berge weiter siidlih sheit (S ; Tab. 3, 4) es i Athioie iht zu gebe, da es dort keie stadige Sheegreze gibt. Das Rhithral weist eie harakteristishe Faua auf ud reiht bis a m hiab (S. 31; Tab. 3, 4 ). Dort folgt eie Obergagszoe, die sih bis a m erstrekt (S. 31; Tab. 3, 4), ud daruter liegt ei Potamal mit eier Faua, die der des GroBteils Afrikas ahlih ist (S ). Akowledgmets The authors gratefully akowledge the followig: Addis Ababa Uiversity (Biology Deartmet) for aommodatio ad suort failities. CIDA for fiaial aid; Natioal Siee ad Egieerig Couil, fiaial aid. The followig exerts for idetifiatios ad ofirmatios: Mr. M.E. BACCHUS, British Museum (Natural History), Coleotera; Dr. K. E. BANISTER, British Museum (Natural History), Pises; Dr. 0. BISTROM, Helsiki, Hydrooriae; Dr. M. BRANCUCCI, Basel, Colymbetiae; Dr. P. BRINCK, Lud, Gyriidae; Dr. R. 0. BRINKHURST, Sidey, B. C., Oligohaeta; Dr. R. W. CROSSKEY, British Museum (Natural History), Simuliidae, ad Atoha; Dr. A. FAIN, Atwer, Simuliidae; Dr. E. GENTILI, Varese, Hydrohilidae; Dr. W. L. PETERS, Tallahassee, Letohlebiidae; Dr. K. M. F. SoTT, Grahamstow, Trihotera; Mr. T. R.WILLIAMS, Liverool, rabs ad seimes from Mt. Elgo; Dr. D. P.WooLDRIDGE, Pesylvaia State Uiversity, Paraymus; Mr. R. KELLERMAN, Deartmet of Earth Siees, Uiversity of Waterloo for water aalyses. Dr. G. R. CuNNINGHAM-VAN SoMEREN, Natioal Museum, Keya, for hotooy of VAN SoMEREN (1950). Referees AGNEW, J. D. (1961): New Baetidae (Ehem.) from South Afria. - Novos Taxa Etomologios (Su. Rev. Etomol. Mo ambique) 25: AXELROD, D. I. & RAvEN, P. H. (1978): Late Cretaeous ad Tertiary vegetatio history of Afria. - [I:] WERGER, M. J. A. & VAN BRUGGEN, A. C. : Biogeograhy ad eology of Souther Afria. - Moograhiae Biologiae 31: Juk, De Haag. BAFORT, J. M.; FAIN, A. & SIBERSTEIN, A. (1977): Simulies du Mot Keya (Ditera: Simuliidae) II. Etude des eseses reoltees ave ue revue des Simulies des motages de l'est Afriai. - Rev. Zool. afr. 31: BARNARD, K. H. (1932): South Afria mayflies. - Tras. r. So. sth Afr. 20: BYSTROM, 0. (1986): Review of the geus Hydroglyhus MoTSCHULSKY ( = Guigotus HouLBERT) i Afria (Coleotera, Dytisidae). - Ata zool. Fe. 182: 56. BoLLow, H. (1939) : Eie eue Dryoide-Gattug aus Abessiie. - Atti Museo Civ. Storia Natur. Trieste 14: Arhiv f. Hydrobiologie, Sui.-Bd. 81

34 34 A. D. HARRISON ad H. B. N. HYNES BoTOSANEANU, L. (1973): Au arrefours des regio orietale, ethioiee et aleartique. Essai de reostitutio de l'histoire de quelques ligees "ool adated" de trihoteres. - Fragmeta etomologia 9: (1979): Quize aees des reherhes sur la zoatio des ours d'eau: Bijdrage tot de Dierkude 49: BRINCK, P. (1955): A revisio of the Gyriidae (Coleotera) of the Ethioia Regio I. - Luds Uiv. Arsskrift. N. F. Avd. 2, 51 (16) : (1956): A revisio of the Gyriidae (Coleotera) ot the Ethioia Regio II. - Luds Uiv. Arsskrift. N. F. Avd. 2, 52 (14): BRoWN, D. S. (1965): Freshwater gastrood Mollusa from Ethioia. - Bull. Brit. Mus. (Nat. Hist.) Zool. 12: (1980): Freshwater sails of Afria ad their medial imortae , Taylor ad Frais, Lodo. CHUTTER, F. M. (1969): The effets of silt ad sad o the ivertebrate faua of streams ad rivers. - Hydrobiol. 34: (1970): Hydrobiologial studies i the athmet of Vaal Dam, South Afria. Part 1. River zoatio ad the bethi faua. - It. Rev. ges. Hydrobiol. 55: CRAss, R. S. (1947): The may-flies of Natal ad the Easter Cae. - A. Natal Mu. 11: CROSSKEY, R. W. (1969): A re-lassifiatio of the Simuliidae (Ditera) of Afria ad its islads. - Bull. Brit. Mus. (Nat. Hist.) Etomol. Sul. 14: DEJOUX, C.; ELOUARD, J. M.; FoRGE, P. & MASLIN, J. L. (1983): Catalogue ioograhique des isetes aquatique de Cote d'lvoire: Orgaisatio modiale de la Sate. - ORSTOM. OCP/VCU/HYBIO 83.2: 178. (mimeo). DEMOULIN, G. (1970): Ehemerotera des faue ethioiee et malagahe. - South Afria Aimal Life 10: DuRAND, J. R. & LEvEQUE, C. (Eds.) (1981): Flore et faue aquatique de!'afrique sahelosoudaiee (Vols. 1 ad 2) , ORSTOM, Paris. EDMUNDS, G. F. (1975) : Phylogeeti biogeograhy of mayflies. - A. Missouri Botaial Garde. 62: EDWARDS, S. (1976): Some wild flowerig lats of Ethioia , Addis Ababa Uiv., Addis Ababa. FAIN, A. & DuJARDIN, J. P. (1983): The Simulium igritarse omlex (Ditera, Simuliidae). Rev. Zool. afr. 97 : FAIN, A. & OoMEN, A. P. (1968): Sur ue simulie du groue eavei aturee e Ethioie (Note relimiaire). - Rev. Zool. Bot. afr. 78: FoRGE, P. (1981): Coleoteres. [I:] DuRAND, J.-R. & LEVEQUE, C. (Eds.): Flore et faue aquatiques de l'afrique sahelo-soudaiee , ORSTOM, Paris. FREEMAN, P. (1955): A study of Afria Chiroomidae, Part 1. - Bull. Brit. Mus. (Nat. Hist.) Et. 4: (1956): A study of the Chiroomidae (Ditera) of Afria south of the Sahara, Part 2. - Bull. Brit. Mus. (Nat. Hist.) Et. 4: (1957): A study of the Chiroomidae (Ditera) of Afria south of the Sahara, Part 3. - Bull. Brit. Mus. (Nat. Hist.) Et. 5: (1958): A study of the Chiroomidae (Ditera) of Afria south of the Sahara, Part 4. - Bull. Brit. Mus. (Nat. Hist.) Et. 6: FREEMAN, P. & DE MElLON, B. (1953): Simuliidae of the Ethioia Regio , British Museum, Lodo. GILLIES, M. T. (1982): A seod large-eyed geus of Caeidae (Ehemerotera) from Afria. - J. at. Hist. 16: