Annual meeting of hydrobiologists: Kara, 23-24 February 1990

| \-A"*' ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA PROGRAMME DE LUTTE CONTRE L'ONCHOCERCOSE EN AFRTQUE DE L'OUEST ANNUAL MEETING OF HYDROBIOLOGISTS Kara, 23-24 February 1990 Openine of the meetine At 9 a.m., Dr Quillevere, Chief, VCU, welcomed all the participants on behalf of the Programme Director and wished them every success in their work. The following officers were then elected for the meeting: - Chairman: Dr C. Back, while waiting for the arrival of Dr C. Leveque, member of the Ecological Group and Chairman for the meeting. - Raooorteurs: Moussa Elimane Diop, ichthyologist, and Fanfode Konde, invertebrate biologist (Guinea team). The following agenda was proposed: l. Presentation of VCU activities ' 2. Presentation of reports of national teams (Cote d'tvoire, Ghana. Guinea, Mali) 3. Geographical and biological distribution of certain species in the Programme area 4. Other matters 5. Discussions between the Hydrobiologists and the members of the Ecological Group (26/2/90). Dr C. Back, Interim Chairman, asked each participant to introduce himself and then gave the floor to Dr Quillevere to present the activities of VCU. I. 1988-1989 ACTIVITIES OF VCU The Chief of VCU dealt with the following points in his presentation: (a) Larvicidine in 1989 It was characterized particularly by the stoppage of treatment in the initial area, the complete coverage of the southern extension, the coverage of Guinea and Sierra Leone, and the start of treatment in Senegal. (b) Insecticides used Five insecticides were used in the Programme area: Abate, Chlorphoxim, Carbosulfan, Permethrin and B.t.H.l4. 2The production of chlorphoxim had been interrupted. The search for a replacement insecticide was in progress. Pyraclofos, an organophosphorus compound, had demonstrated an excellent efficacy during the trials carried out in 1989 and therefore appeared to be a potential candidate. (c) Insecticide rotation The different larvicides were rotated according to the hydrological conditions of the watercourses treated with larviciding suspensions at high water. This technique allowed the greatest possible insecticide and flight-hour savings to be made. (d) Reinvasion This problem was solved by the extension of larviciding in Guinea and Sierra Leone. The effect of the larviciding was felt up to north-western Cote d'tvoire. (e) Transmission The points where it had not been completely eliminated were in the east of the border with Nigeria: but this transmission remained moderate. In conclusion, the results obtained were good and supported by the excellent entomological results in the whole Programme area. 2) Insecticide research (a) New larvicides A new pyrethroid, beta-cyfluthrin (Bayer, OMS 3051) had been very effective on the blackfly larvae and would be tested further in 1990. A new organophosphorus compound (OMS 3052, Bayer) proved to be ineffective and was discarded. (b) New formulations New formulations of carbosulfan (FMC Int.) in micro-capsules and micro-emulsions were tested in gutter. The micro-emulsions would be tested in river and on the non-target fauna in 1990 as well as a new formulation of bioresmethrin (Roussel-Uclaf). New formulations of B.t. H-14 from the company Solvay were also being analysed. (c) Research related to aerial ooerations Diagrams on the carry of the operational insecticides had been produced. As part of the optimization of aerial operations, a discharge forecasting programme had been developed by ORSTOM(IIRSDA Adiopodoume). A programme for the optimization of dosages and flight plans had also been produced by the University of Quebec 6 Trois Riviires (Canada). (d) Susceotibilitv monitorine The monitoring of susceptibility to the operational insecticides was continued in the OCP area. The relative susceptibility to pyraclofos and the other insecticides was particularty studied in order to assess the risks of resistance to this new product. The 1987-1990 data were reanalysed and stored so as ro better evaluate the thresholds of susceptibility of the btackfty populations. 33. ectivities of the OCP Hydrobioloev Section in Cote d'Ivoire. Ghana and Toeo The OCP Hydrobiology Section continued in 1989/1990 with the monitoring of the entomofauna of the rivers of Cote d'lvoire, Ghana, Mali and Togo. It also organized and participated in the evaluation of the medium-term impact of pyraclofos on the non-target fauna of the White Bandama. Furthermore, it conducted comparative gutter tests of new carbosulfan formulations and, as recommended by the last meeting of the Ecological Group, pre-larviciding data were collected on a number of watercourses in Sierra Leone. The entry of the routine monitoring data was continued in the OCP headquarters in Ouagadougou and, as recommended by the tenth meeting of the Ecological Group, a year-book and historical data on certain stations were produced and distributed to the national teams. The monitoring of River Amou in Togo had not revealed any harmful effect of B.t. H- 14 on the principal taxonomic groups. The abundance of most of these taxonomic groups had not changed over the years though there had been seasonal fluctuations. The fauna was dominated by the Chironomidae, which could be explained by the use of agricultural pesticides in the coffee and cocoa plantations lining River Amou. Despite the carbosulfan tarviciding, the faunistic situation of the Marahoue had remained good. However, it was observed that among the Ephemeroptera, the Caenidae were now dominant, while in previous years the Baetidae had been predominant. Moreover, a gradual increase was observed in the relative frequency of the Hydropsychidae on the rocks (after the high water) as well as a decrease of the Chironomidae. On the whole, the fauna seemed not to present major disruptions. The faunistic situation of the White Bandama in 1989 was not fundamentally different from that of 1988 The drift increased form December 1988 to April 1989, with a rock-fauna density which becanre considerable in February 1989. On the Comoe, the use of permethrin led to an increase in the drift index, with an increase in young Mockokidae (mainly Synodontis) in the drift. At Bamboi on the Volta in Ghana, some effects of permethrin on the drift were observed. As in 1988, a decrease of the Tricorythidae and Heptageniidae was noted again. II. PRESENTATION OF REPORTS OF NATIONAL TEAMS A. ICHTHYOLOGY (l) Ghana Three rivers were monitored: the Oti, the Pru and the Black Volta. The monitoring protocol used was the one established by ocP. The catches per unit effort (CPUEs) were in general low compared to those of the previous year. The condition of the fish in 1989 remained in general at the same level as in 1988. As regards length structures, for most of the species, they recalled those of the previous year. The results obtained in 1989 were therefore, broadly speaking, comparable to those of 1988. 4(2) Cote d'Ivoire 4ArsE€ Six series of sampling were carried out at Niaka, Cbfue and at the Road Bridge on the Leraba The data analysis showed that: - the most representative species of the stations were still present in the catches; - the numerical and weighted CPUEs were not very different significintly from those of the previous years' monitoring; - the coefficients of condition remained dependent on seasonal variations and hydrological conditions; - the study of the gonadosomatic ratios (GSRs) indicated that many species reproduced in the rainy season; Despite the possible harmful effects of the larvicides, they had therefore not shown any drastic and irreversible effect on the fish fauna. (3) Guinea Three stations were monitored. [t was mainly in the evolution of catches that changes were recorded. The CPUEs showed some decrease compared to the previous year although they were relatively high. The species-richness showed some stability as well as the mean coefficients of condition of the principal species. As regards reproduction, the results obtained corroborated those of 1988. The action of the larvicides was not evident and remained to be verified. (a) Mali Eight missions were carried out on the Baoule at Missira. The results obtained showed a normal CPUE trend. The coefficients of condition of all the species remained stable. Study of the gonadosomatic ratio made it possible to know approximately, at high water, the reproduction period of most of the species. The species-richness was higher in April and October but the diversity was [ow. ln conclusion, the results of the monitoring of the fish fauna by the different teams had not indicated any harmful effect of the larvicides used. This was important at a time when new insecticides were being introduced into the antiblackfly larviciding. B. INVERTEBRATE BIOLOGY (l) Guinea national team The invertebrate biology monitoring covered only one station: Sassambaya on the Niandan. Two types of activities were carried out there: - routine monitoring, - special studies on the drift of organisms in pools and vertical distribution of drift 5Only the monitoring results will be presented here. The protocol used was what was recommended by the Programme, but it was supplemented with two right drift collections (500 micron) one hour after sunset. It should be noted that the Baetidae (Centroptilum + Baetis), Caenidae, Orthocladiinae and Chironomini were the most abundant in all the samples. The treatment of the Niandan was resumed only in March 1989. It was therefore not very easy to talk of direct impact. The different results obtained from the drift indices showed that, in the absence of larviciding, seasonal variations and hydrological conditions seemed to be responsible for different fluctuations in these indices. (2) Ghana national team Despite the decision of the Ecological Group to entrust the monitoring of the aquatic entomofauna to the OCP hydrobiology section, the Ghana national team continued, at its own expense, the sampling of the fauna at Bamboi/Black Volta, Sabari/Oti and Asubende/Pru. On the whole, the larviciding seemed to have resulted in a reduction of the abundance of the Leptophlebiidae and Heptageniidae on the Oti at Sabari, and the Tricorythidae, Hydracarians and Heptageniidae on the Black Volta at Bamboi. High drift indices were recorded at Asubende on the Pru, these being certainly related to the suspension of larviciding on the watercourse for five months. The tnstitute of Aquatic Biology, Accra, carried out prospections also on the Black Volta upstreanl from Bamboi (mainly Bui area) in search of a possible monitoring site to replace Bamboi. [n the absence of any adequate site, it was proposed to maintain Bamboi as a monitoring station. III. GEOGRAPHICAL AND BIOLOGICAL DISTRIBUTION OF CERTAIN SPECIES IN THE PROGRAMME AREA ( I ) Eohemeroptera The results of the light trapping undertaken at more than 120 sampling points in Guinea, Sierra Leone, Mali, Cote d'lvoire, Senegal and Togo had made possible the establishment of the distribution of Adenoohlebiodes s.s. (Ephemeroptera: Leptophlebiidae) and the genera Oohelmatostoma and Pseudooan nota of Baetidae). As regards Adenoohlebiodes, only one species (A. massirus) was widely distributed in the Programme area. Other species (A. rubeus and A. ornatus) were found in the forest areas and (A. adrieni, A. callasae) were localized in the Fouta Djalon. With regard to the Baetidae, it had been established that Pseudonoannota bertrandi, P. muqaninani and Oohelmatostoma camerounense had a wide distribution in the whole Programme area. On the other hand, P. modesta was encountered in cold waters. (2) Trichootera Mr F.M. Gibon undertook a consultantship for OCP on the geographical distribution of Trichoptera in the Programme area. He prepared a report on it which was presented. It emerged from that work that most of the species were widely distributed in the big as well as samll rivers. However, some species had a localized distribution (either in high altitude, savanna, forest or coastal biotopes). It was particularly interesting to note that, in general, most of the species had the possibility of colonizing different types of watercourse. 6(3) Fish Two main types of fish fauna could be distinguished in West Africa: a Sahelo-Sudan fauna found in most of the river basins (Senegal, Gambia, Niger, Volta, Oueme, Lake Chad and the Nile) and a Guinea fauna limited to the small coastal basins to the south of the Guinea ridge, towards the Fouta Djalon and Mount Nimba in Guinea, Sierra Leone and Liberia. The Guinea fish fauna presented certain affinities with those of the Cameroon area. Some species had been able to reach River Oueme and River Mono. IV. RECOMMENDATIONS A. Of the national teams (Ichthvotoev) (l) To OCP (a) After using them for three years, the teams would like their batteries of gill nets to be replaced; (b) To solve the problem of the Zodiac boat in Guinea by replacing it, for example, with an aluminium boat; (c) To review the question of PH-meters which do not seem to be very precise at present; (d) Introduction of research workers in the national teams to certain data processing statistical methods (factor analysis, etc.); (e) To collect all the data on species reproduction and send them to Dr Paugy to synthesize thenl and see to what extent they could be published; (f) It would be desirable to establish a sort of hydrological year-book in order to make available to the teams the whole hydrological information on the monitoring stations. (2) To the Ecological Group (a) To maintain the monitoring stations with the same monitoring frequency; this would facilitate inter-annual comparison of the monitoring results. B. Of the national teams (invertebrate bioloev) (l) To OCP Exhaustive analvsis of drift data - To see if the drift could reveal insecticide impact; - To choose the best drift method capable of revealing impact; - To continue with the field (vertical distribution and contribution of reach) and theoretical (index of aggregation) research on drift. 7(2) To the Ecoloeical Grouo (a) To choose stations in western Guinea for the collection of pre-larviciding data, considering the fact that some had already been selected during prospection missions; (b) To replace carbosulfan with pyraclofos on the Marahoue to enable the long-term effects of the product to be revealed; (c) To continue the special studies on drift; (d) To maintain Bamboi as an entomofauna monitoring station in Chana. MOTION ADDRESSED TO VCU The national teams seized the opportunity offered by the meeting to praise the efforts of VCU as regards the processing of the aquatic monitoring results and expressed the wish for that initiative to be continued in order to enhance the quality of the progress reports. 8LIST OF PARTICIPANTS Cote d'Ivoire Dr K. Traortl Institut d'Ecologie Tropicale, 08 B.P. t09 Abidjan 08 Ghana Dr E.K. Abban and Dr J. Samman Institute of Aquatic Biology, P.O. Box 38, Achimota, Accra Guinea M. E.M. Diop et M. F. Konde Equipe nationale Oncho Kankan Mali M. M.K. Traorri Cantonnement forestier de Kolokani, R6gion de Koulikoro ORSTOM Dr J.M. Elouard 2051 avenue du val, Montferrand,34032 Montpellier, France Dr D. Paugy Mustium Nationat d'Histoire Naturelle, Laboratoire d'Ichtyologie, 43 rue Cuvier, 75321, Cedex 05, France Ecoloqical Grouo Dr C. Leveque (Chairman) Directeur de recherches, Mus6um national d'histoire naturelle Laboratoire d'Ichtyologie, 43, rue Cuvier, 75231, Paris Cedex 05, France Secretariat Dr D. Quilltivere, VCU/OCP, B.P. 549 Ouagadougou, Burkina Faso Dr J.F. Walsh, VCU/OCP, B.P. 36 Kara, Togo Mr S. Sowah, VCU/OCP, B.P. 36 Kara, Togo Dr C. back, VCU/OCP, B.P. 1474 Bouak6, Cote d'lvoire Mr L. Yam6ogo, VCU/OCP, B.P. 549 Ouagadougou, Burkina Faso Mr J.M. Tapsoba, VCU/OCP, B.P. 549 Ouagadougou, Burkina Faso Miss K.C. Nignan, OPD/OCP, B.P. 549 Ouagadougou, Burkina Faso