Summary of annual report for 1988/1989: Guinea national team

ONCIiOCRCIASIS ONIBOL PffiR,AI.tIE IN WESI AERIG PRreRAMI'IE DE LUrIE OoNIRE LTONCTXCCERGE m{ ArRIQtrE DE LrCuEgr ruIIGICAL GROUP Eleventh session IG::a, 27 Februart'- 2 l,larch l-990 wrys,J/t{YBro/eo . 13 ORIGI}BL: FRM'ICH suMraRY oF ANNUAL RmRr FOR l_988/L989 (Odrca National Tbam) Fhnfode l(orde II - INVERTEER}TIE BIOIOGY tlre irrvertebr:ate biology nonitorirg cc,vered only one station: Sansambaya on ttre Niardan. ttre activities of this section were centred rnainly on: aquatic monitorirg of tlre Niardan at Sansambaya; special studies. I. Acnratic monitorinq The monitorirg protocol us€d is that reccnnrerded by tlre n:ogranmre but it v,,as s1i$rt1y nrdified: Day drift 500 pr, bpo at L3hOOhy drift 2OO tt two at 14h00Ni$lt drift 500 p two at one hcr.rr 30 min. afEer sunsetNi$tt drift 20o 1t" two inunediately aft€r tlre night drift 500 pr. . Table II(b) suurunarizes all ttre 1988/L989 nonitorirg activities. Ttre predom- ixance of tlre Baetldae (centrrcptilun + Baetis), Caenidae, Orthocladiinae aira cfd:oncrnini in all ttre collecEions stro.rld be noted. Ihe kictroptera were not very atr:rdant ard varied little in rnm0cer ard rerative frequencY. The treabnent of tJ-e Niardan r,rias sta:ted only in March 1989. ft is tlrere-fore not eaqg to talk about fupact. the different restrlts we obtained from thedrift indices shcry th,at in the absence of treatrrent, seasorlEll variations andhydrobiological corditions are responsible alone for tlre d.ifferent flusbuations of these irdices. 2- II. Special shrdies As palt. of special studies, t:r^ro studj-es lrcr€ carried qrt, both on reaches of the Niardan at Sansanbaya. (1) Sbrty of organisn drift in the pool: It appean:s, f:sn ttris str:dy, thattlte dcr,,mstream drift, (a11 stages ard late stages) is g:eate than tlre rrystreamdrift durirg ttre ni$rt ard tlre afEernoon (Fig. 17 arxl L8). only the caeainae anO centrpertilun + Baetis, dlich sesned to have a preferenoe for the lcrrtr crrrr:ent, haddeposits in the pooI. (2) Study on vertical distritxrtj-on of drift: This sturl1,r strcns that: trro hlpottreses can be prt forward for the drift Erantity according tot].e curr:ent: . either there is rp relationslr-ip between the drift irxto< and the cuffent speed rrtlatenrer be ttre ta><oncnr-ic a:ulp considered; . or there is a drifb decrrease that is il correlation with increasein the current ryeed. tlrere is a clear correlation betlveen tl.e aturdance of irnrertebrates in the drift ard current speed; ttre higher tJ.e cur::ent q>eed, the greater tlre nunber of invertebrates caught is. tlte surface drift seems to be nrore representative ttran ttp bottomdrift. It should be noted tlrat ttre drifb with nets at l<nee ]evel (case of drifts at ttrree levels) gives ncre or less uniform results. for the seasonal evaluation of drift, we obsenred t}at ttre akunclance of irnrertebr:ates in t}re drift. was g:reater in ttre flood-subsiderrce periodin the nronth of Febnraqr. A1I special studies on distribution a:e beixg continued.