Report on activities 1981-1983 (published in February 1984)

:' @ :::::,ffirffi:r;::^ sANrE UNIVERSITY OF BENIN, TOGO IIIGHER SCHOOL OF AGRONOMY REPORT ON ACTIVITIES l98l-1983 (published in Februery 1984) by r. Bouraiure, A. #iL,and K. Ackotia PORSWORD Togo shares its river network with neighbouring countries: the Volta Basin with Ghana to the t^rest and Upper Volta to the north, and the Mono BaEin with Benin. It is only the basin of the Sio and the Haho which is entirely within Ghe TogoLese territory, together with the small An6ho Lagoon Basin. It is theref,ore certain that most of the apee,les and species groups encountered in our samples may exist in the neighbourlng countries-. Ilowever, it would seem that part of our tGrritofy, together with part of Benin, form a transitional zone betrreec arest and 6aagr with a sp.eital fauna. Some authors aecribe this to the existence of a chain of mountains running.southnest/Edith-east, forming a prolongation of the Ghanaian Akwapin massif and the Atakora uessif and including the Togo, Fazio and Malfakassa mountains The aquatic monitoring advocated by th6 Onchocerciasis Control Prograrmre involves'in principle the whoLe river network being treated with insectigideE, but our studies are liaited to the 0ti, the Kara, the Sio, the Arnou and the Meno.' The issue of this document doos not cgnrtitute formal publication. lt should nqt bo revirwcd, abstracted or quoted without the agreement of the World Health Organization. rAuthors alonc arc responsible for views expretsed in signed articles. ocP/vcu/flYBro/84. 10 ORIGINAJ,: FRENCH I.IORID HEALTIT ORGAI{IZATION ONCITOCERCIASIS CONTROL PBOGRAMME Ce documcnt ne qonrtitue pas unt publication. ll ne doit faire l'obiet d'aucun compta rcndu ou rdsumd ni d'aucune citation rano l'autorirtion de l'grganisation mondialc de la Santd. Lff opinionc exprim6er dans les articles sign6s n'lnglge nt que leurs auteurg. ocP/vcu/HYBro/84. 1 0 page 2 UPPER VOLTA FIG. 1 =z I,L' m TE o- 0- u) IT lt) stl (\ o, 4 rl ,l J t'l ta ri rl ri 1 II { )i l.-' )o Non doo"i VOLTA BASIN (OTI) (Main watercourses) West: Kanboaga Kountonn6 Gambera EasE: Naboulgou Kara M6 MONO BASIN (MONO) Aou Ani6 Amou Chra OgouE East: Noukou6 Ogou6 LAI.G TOGO BASIN (SIO AND HAHO) (Main watercourses) (Main watercourses) @J West: Pasa oT West: Li 1i East: Yoto ANEHO LAGOON BASIN West: Zouvi Agbanon Woto6 Togbadj a t- I /LOME I.AGOON ocP/vcu/HYBro/84. 10 page 3 PREAMBLE This report covers not only the missions which at first took pLace et irregular intervaLs in the company of experts from Bouakd (in 1981), but al"so the much nore regular missions carried out since April 1983, together with samples sent to us by the Kara sector frorn the sanpling sites on the Oti and Kara, both in the VoLta Basin, and on the Oga in the Mono Basin. The dates and places of sampling are shown in tabular foru below' TASLE 1 Dates Places Corunente 11, 18, 25 February L982 OTI/MANGO Sent by the Kara,$ector 10, 18, 25, 3L March 1982 7, L4, 2L, 29 April 1982 21 January 1982 I(ARA/I..ANDA-POS.ANDA 1, ll, L6, 22 March 1982 22, 30 April 1982 5, 10' L7, 26 May 1982 4, 8, L7, 24, 30 June 1982 13, 28 February 1982 A},IOUTCHOU/OGA 17, 31 March 1982 16, 30 April 1982 17 May 1982 2, 24 June 1982 I. NOTES ON THE SAMPLES SENT BY THE KARA SECTQR These samples are from the road-bridge sarapling site on the Oti, the Landa-Posanda site on the Kara and the Oga site on the Amoutchou. No non-biotic ecological feature has been noted so fhat it is only the raw data that have been entered on the standardized record cards. It Ehoul.d be noted that these samples were taken with a Surber net of unknown size (but probably corresponding to the standard OCP size) between January and May 1982. A. ROAD BRIDGE ON THE OTI (MANGO) 0n1y a single sample was sent per week, which means that conclusione uust not be hastily drawn. Thus, the Ephemeroptera (mainly Baetidae) and Diptera (OrthocLadinae) occupy the Bame pl.ace in aLmost all of the samples. Developments in relation to tiue are shown in the following tab1e. ocP/vcu/HYBr0/84. t0 Page 4 TA,BLE 2. ROAD BRIDGE ON THE OTI Aluost pl1 the t4xa eneountered became relatively important in March. B. I.ANDA-POSANDA ON TH3 I(ARA Density of the fauna captured (per Surber unit per week) (see Table 3). TABI+E 3. LANDA.POSANDA ON T}IE KARA: DENSITY OF THE FAUNA CAPTURED PER SURBER UNIT PER WEEK Fauna \$rioa January March Apri I May June Helminths Ep[reueropCera Trichoptera Simulium damnosum Other Simullidae Chironomidae Other Diptera Water mites Others 4.5 2.5 457.5 o. o0 44.00 0.oo 1 .00 26.25 L.25 490.25 o. oo 112.O0 1.50 6.50 9.50 o. oo 53 o. oo 7. OO 38. OO 1.00 o. 50 o. 50 7.75 o.25 148. 50 253 55.25 35.50 L.25 o.25 3. 50 43.60 o. oo 907 44.20 80.40 333. 60 3.40 5.60 r8. 80 Trichoptera (Hydropsychidae) and Diptera are the most important elements in the benthic fauna. February March April No. o7 No. 7 No. , 0ligochaetae Ephemeroptera Trichoptera Chironouridae Simuliidae Ceratopogonidae Other Diptera Coleoptera I.Iater mites TotaI o 5. 33 I 21.33 3.66 o 2.33 o.33 o,33 34. 31 o 16.53 2.9L 62.L6 10. 66 o 6.79 o.96 0. 96 ,::" I 3.oo I I 42.62 I7.5 24.37 o.37 o.62 0 1.06 24.44 2.84 40.45 7.11 23.t3 0.35 0.58 0 4 14.50 3.25 26 o.25 1. 75 o.75 0.50 0 7.76 28. 15 6. 31 51.45 0.48 3. 39 r.45 o.97 o ocP/vcu/HYBro/84. 1 0 Page 5 A11 the invertebrate fanilies were found at this sanpling site, particularly from May onwards. If the species had been determined we would have been able to calculate the index of diversity, which would probably have been high, thus indicating that the Kara provides a good biotoPe' not hostile to a lotic zoocoenosis. This is a sampling site which must be borne in mind when aquatic monitoring takes place. OGA ON THE A},IOUTCHOU The samples were taken from artificial substrates and it been suboerged. The fauna col-lected is poor in families as The douinant groups are the Ephemeroptera (Baetidae) and Chironomidae. is not knowa how long they had welL as individuals. the Tanytarsini subfanily of the TABLE 4. MEAN/MONTH/SURBER UNIT February March April May June Coelenterata Oligochaeta Hirudinea 0stracoda Baetidae Caenidae Leptophlebiidae Heptageniidae Tridros i t idae Zygoptera Ecnomidae Hydropsychidae Leptoceridae Ceratopogonidae Other Simuliidae Chironominae Tanytarsini Orthocladiinae Tanypodinae Other Diptera Elmidae [,later mites 3.3 r.5 o.5 1 o.5 0.5 o.5 o.5 0.5 o.5 2 I 1.5 0.5 3.5 4 o.5 o.5 I I 2 2 I 2 1 I 57 1 2 I 0.5 o.5 1 2 I o.5 0.5 I o.5 2 1 25 o.5 1 o.5 6.5 The fact that it is not known how long the artificial substrates have been in the river makes it iupossible to determine the rate at which new obstacles are colonized. It should be noted, however, that May and June were the richest periods for the fauna (see Table 4). OCP/VCU/HYBIO/84. 1 O Page 6 II. NOTES ON MONTTORTNG ACTTVITIES ON TIIE SrO, MONO AND AMOU General coments Two missions carried out in 1981 with hydrobiologists from Bouak6 could have laid a basis for the launching of monitoring operations. Unfortunately, it was impossible to continue because of the difficulties of establishing a national team with a minimum of two or three members and on the other hand the lack of information concerning the sending of funds to enable monitoring activities to proceed effectively. Until 1982, the sarnpling sites selected, i.e. those at Kati on the Sio and at T6tdtou on the Mono, together with that at Anou-Oblo on the Amou, seem to be the best on the three rivers, since there was permanent flow there. Since 1983, it has been noted that there is low lrater in the Sio in February and March, which is obviously unfavourable to the establishment of a blackfly zoocoenosis. An extraordinary fa11 in the leve1 of the Mono occurred, so that slight changes had to be made in sanpling places. It is only the Auou which seems to maintain normal flow, at least at the sanpling site, which is not far from its source. Moreover, the artificial substrates laid for the first time in December 1983, were above the water 1evel in the Sio. Furthermore, the Higher School of Agronomy norir possesses an analytical laboratory, so that it has been possible since November 1983 to determine other physicochemical factors in the qrater. These include total hardness, alkalinity using the phenolphthalein test(generalLy zero), the pH (approxinate value) and calcium content. If such analyses are to be continued, we shall need a range of chemicals and glassware. Obviously analysis of the effect of these factors on the fauna would be too bold a step at the moment and it may be wondered whether they will have any considerable influence on the preferences of the species in particular rsatercourses or at particular tirnes of the year, It is therefore only the samples taken with the Surber-type sampler and the day-time and night*time drifts that have been examined. A. SIO.KATI No further knowledge has come to light. The site is an excellent larval breeding placefor blackfly. The species S. adersi, S. unicornutum and S. damnosum appear in the samples, exeept in February and t"tarcnllif,T-ch se., to-EeJ.rioas tro"ffi-Itre esrablishmenr of a varied zoocoenosis. This is because the water 1evel falls and the river even dried up completely in 1983. very recently the sio has again been short of water. Moreover' the blackfly very rarely come down beyond hlounougba (see the map). The monitoring samples do not seem to provide enough blackfly larvae, but when the sampling method takes into account the substrate and the speed of the current, or when certain leaves of trees are lifted, the larvae seem to be of the colonial type. The doninant grouPs are sti11 Ephemeroptera, Chironouidae and Trichoptera. (1) Before 1983 The only samples taken rdere those of February and December 1981. | 50uree ) rIG. 2. SIO RIVER BASIN ocP/vcu/uYBro/84. 10 page 7 AlETA Turu (S,o*yi) Nou Wo u4ou e a,tr k oltr' I t t Illfeui '. bampling stations lvl tsstorv : 7a v€ .10 Tooat'eKo-pe KEtEG.Ou"oA Lo. To3o ocP /vcu/HYBro/84 . 1 0 page 8 In the day-tine drift (as a percentage of the fauna collected) Ephemeroptera Trichoptera Chironomidae other Diptera (not including blackfly) Total In the night-tine drift Ephemeroptera Trichoptera Chironouidae Other Diptera Total The percentages feLL when Coleoptera particularly in February. They seem to Surber Epheueroptera Trichoptera Chironomidae made their appearance in be resistant to the fa1l 54.09 the night-tine drift, in water level. February 1981 20.73 2.43 37 .80 60 .96 29.26 90.22 December 1981 14.55 2 .30 68.85 85 .71 5.49 91.20 45.34 2.37 12.65 7.29 43 .83 1 .88 3.22 s.l6 67 .65 Total 89.04 76.31 While the couposition of the fauna seems to be the same in February as in December, the high value of the ratio NTD/DTD in December and the faunal abundance N = 175 as cotrpared with N = 103 in February, shows that the ecological situation was good in December. (2) In 1983 Samples were taken in April (when monitoring was launched), May, July, November and December (Table 6). As before, the preponderant groups were Ephemeroptera, Chironomidae, Simuliidae and Trichoptera, although the latter were very scarce in April and May, even in Surber samples. Day-time drift (DtP) February 1981 3.22 4.19 81.63 December 1981 21.44 2.62 52.25 November December Ephemeroptera Trichoptera S iuul iidae Chirononidae April 15.93 0 .80 7.56 64.34 ry 19,34 1 .26 16.81 46,77 July 30.40 10.81 9.45 27 .71 24.15 7.24 3.26 29.22 12.90 5.01 2.15 33.33 Toral 88.63 84. 18 78.37 63.87 53.39 ocP/vcu/HYBro/84. 10 Page 9 aJ) frfHHH(a z ETo F]t It{ ho.. z&Orllr{€t1 &PDFl cr!Or\>lzfr.l v F{o o\ Fa t op ao o oA Et .scrl .nrrr@OO\co@!9o +U.O(\l\Ornl,)NC{O\O .ll.Fa(\lt\NO6l'{(\lo(nrn6l ln oo 1v oooOrn-S@l- .SOrnO\ ooooo\O\O\r\O(\l-t@ .t t\ .:l ('l A Fa -t Gl(t! 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It should be noted that in April many beetles and helainths were caught, uaking up aluost 3OZ of the fauna. Generally speaking, the fauna was very abundant in May (N = 359) (Table 7). Perhaps this threshold figure shows a return of the zoocoenosis to normal after the sudden shock of condiEions in February and March. It should be noted that the ratio NTD/DTD is lower than that recorded in November and December. B. MONO-TETETOU This is a site under the road bridge on the site of an old bridge, the debris from which(concrete slabs and culverts) constitutes solid substrates for the fauna. Here again, it is the Epheneroptera, Chirononidae and, to a lesser degree, the Trichoptera thaE dominate. The biological feature of this sampling site is the presence of an important crustacean fauna (Copopeda and Cladocera) which exceeded 10 000 in Apri1. (1) Before 1983 There were turo missions - in February and December 1981. The Ephemeroptera, Trichoptera and Diptera (Simuliidae, Chironomidae and others) make up almost 9OZ of the day-time and night-time drift and over 952 of. the Surber samples. Although t.here was suffered in February. Night-time drift permanent flow, some groups other than those already mentioned February 61.83 4 .03 0 .85 6 .50 14.72 December 64.09 11.40 0.51 9.56 4.O9 Total 87.93 89.65 ocP/vcu/EYBro/84. 1 0 Page 13 Surber samples Ephemeroptera Trichoptera Simuliidae Chirononidae Other Diptera Total The very high percentages of these three Diptera) in the fauna colLected by the Surber Chironomidae. 98.44 96.75 major groups (Ephemeroptera, Trichoptera and sampler is due to the iuportance assutred by the February 45.12 6.69 1.58 41.14 3.91 December 38 .5s 2.40 1.60 50.20 4.01 (2) In 1983 There is no obvious evol.utionary trend. The population (N = 100) seerus to be stable in July (before the floods) and in November and December (after the floods). Ilowever, while Ephemeroptera are the most abundant fauna on the rocky substrates and in night-tine drift, Trichoptera and Chirononidae are alnost as important in these two rnethods of sampling. On the other hand, in April and May, Chironouidae dominate, whichever of the tlco Eethods is used. Crustaceans mede their appearance, exceeding 10 000 organisms per Surber drift unit. The genera frequently encountered are Copopeda: Cyclopidae, Calanidae and llarpacticoidae. Apart from the crustaceans, faunal composition ruuong the dominant groups is as foLl.ows(percentages). Surber sampler (Table 10) April 2.79 0 0.23 96.16 April t0.30 0 0 45 .50 Maz 22.40 0 .54 7 .10 59.01 Mry. 4.87 0 .59 3.39 35 .58 July 54.68 30.00 o.17 13.96 July 30.7 1 2.62 3.00 11.23 46.81 11.79 2.80 35.01 44.81 12.73 s .66 30.8 1 November December Total 99.18 89.05 98.81 96.41 94.01 In day-tiue drift: In April and May the usually dominant groups were relatively scarce because of the importance assuued by the crustaceans and lrater nites on the one hand and the very smalL nuuber of larvae of blackfly and Trichoptera that were caught. Ephemeroptera Trichoptera SinuLiidae Chironomidae Epheueroptera Trichoptera Sinuliidae Chironomidae November December r 9.86 2.89 0.31 11.31 25.46 4.29 2.00 23.17 Total 5s.80 The 1ow representation, particularly in is due to the drift of many fry, Collembola, over 502 of the fauna eollected. 4s.43 47.56 34.37 54.92 November, of the and unidentified groups usually dominant (34.372) crustaceans, which represent ocP/vcu/HYBro/84. 1 0 Page 14 alt E:)-{Hl{U'vlrlo Fl zD h Eo.. vdoErHE14d =bFl UIo\>lzlll -v @ CA F{ l. oA Eo(., tuA B.e rnoooiooo r,l.it\ONOoo.i.O t.ltt.@NF{O.sOON(v'l t,l oo F{ I tz oooooooo(rl 6l@0O.$610 l.l1l.O\F.Ol't6lOOr{ Fl 6l o@ o\ .if @ o\ ?rl{ ctl al{3oh }t (\IO\@.,'@F{\ONrn '{\OrnHdOrOdF{ lll.tn\OFaF.O(7lOOr{ .lf .+ oo tv OOOOOOO.$ €O(\IO(\I\O.s'c\l .f\o1ll.Fl'trnoO6lOOC') .nl 6l (') r-a: .$ .if \o F{ d rlrladDU' ,rfH et{x kl2o a ,{H F{Ha Z, FTo FitrH&a fro zoH ts Jo t{ H @ o\ r{ l{ o .o E o o o)o oHa aH }. 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N @Or\\Or|\,\oodor@cfl lll.l. -f,ooc.)oo r,1(fld oo tz _o o o o o oNNc'.l.'fO\a ll l.l.\rrno\OdO\O Cn .{ o\a r* h(! x N \?!n.{OO\gOOCI\O(\OF\O\rldr{r.$d6,1 tn oo d tz ooooooooooNc!\O\O-t\O\t-?@\a@oNoooodo c! o\o \o cn A ,.A x Or ci \O tn !n Or F\F\c.litCnO -ltrNO\oOOOO o\ oo d t7. ooooo\O @ \t -{l olr..tt .r\oooodo \, N .J o o,(t .! 1, 30to,..al.(u(,(,trootl.o\rorroo) o.or(o.;ooal{trqAtTOEO-iO'.lFEo,i6aa.JEl.fOO'..COAQt,diJ6trl.or.'Clr6?ri.!oooEoli';E';aiEr{r'AEEk.;EouOcrol|J(;IF..nO()o(J3'Eo (t t, oH OCP/VCU/HYBIO/84. 1 O page 16 a 14H tsHaz 14n FI z5 fq fqo zoH H FlO>^dfrl f4 Fqd ..p ci u) oo\o,lz o ts E] E{ 14H Iozo d rI] Fl Fq H ocP/vcu/HYBro/84. l0 Page 17 In night-tine drift April 16.54 0 0 33.77 Ier 58 .56 0 .23 0 14.40 July 54 .68 4.20 4.78 5.26 63.63 7 .77 0.28 2.33 35.94 5.s 1 0.51 6.54 November December Ephemeroptera Trichoptera Siuuliidae Chironomidae Total 50.31 73.19 68.92 74.01 The remark already made would have been valid for the unknown reason, the Epherneroptera were highly represented identified fauna also retained its importance. 48 .50 night-time drift but, for some in the drift, although the non- c. AMOU.OBLO This is a site situated not far from the source, where the river has permanent flow and the water is always fresh, because of the nearness of the mountains. The Aoou, although situated in the Sio zone, runs into the Mono, of whose basin it therefore formE a part. (1) Before 1983 There was only one visit - in December 1981. The features of the fauna were no different from those on the Sio. The Chironomidae, followed by the Ephereroptera, dominated in the samples. The Chironomidae represented over 502 (Table 11). NTI)DTD Surber sample 4.51 2.65 o.92 79.53 9 .71 Ephemeroptera Trichoptera Sirutrl.iidae Chironomidae Other Diptera 10.40 0.80 5.20 69.20 5.80 18. 13 4.17 3.34 52.20 10.92 Total 92.40 88.75 97 .33 The fauna is therefore dominated by Diptera and Ephemeroptera. (2) In 1983 The Amou was very rich in Ephemeroptera, Trichoptera, Simrliidae and, above a1L, Chirononidae throughout the yeat. The Surber unit catch usually exceeded 300 organisrns(Table 12). The faunal composition of the dominant groups is as follows. Surber samples April 10. 78 5.14 2.00 79.91 ry 13.18 8.32 1.84 73.96 JuIy 3s .38 5. 19 1.29 52.18 15.59 7 ,44 3 .96 64.20 12.64 3 .90 1.25 74.52 November December Ephemeroptera Trichoptera Sirnuliidae Chironomidae Total 97.83 97.30 94.O4 91.29 92.13 ocP/vcu/HYBro/84. 10 page 18 (t) rr1H tsHav FIo -1 zp h t{o 7&or{HEIt4c/DPFl u:C) \.>|z[4v F{ @ o\ Fl t{ o ..o E q.l o oA 8.e F{ F{ \O rnFa'{.$@t. 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Their iqortance is nasked by that of the coelenterates and helninths during the day-tirne drift in April and May. The NTD/DTD ratios do not show excessively high threshoLds and are al.uost all the saae, thus indicating a zoocoenosis that remrins stable throughout the year (Table 13). CONCLUSION In the three sampling sites studied, Ephemeroptera, Trichoptera (very ecarce) aud Diptera (Chirononidae and blackfly) account f.ox 90% of the total fauna collected. In February and March, the Sio has for several years been hostile to the establishroent of a varied zoocoenosis. The drying-up of this river is certainly raising problems of recolonizatiot for species whose cycle ends before the low-water period and problems of survival for groups with an annual cycle. The fauna of the Amou at Amou-Ob1o is stable since there is petmanent ftos there. Large numbers of crustaceans are rnaking their appearance in the fauna of the Mono(10 000 organisos/Surber). It should be noted that these three saryling sites represent excellent blackfiy larval breeding sites.