The seasonal variations, spatial distribution and interrelationships of rotifers in Opa Reservoir, Nigeria were studied and the relationship between rotifer species and certain physico-chemical parameters of the water described. The population density of rotifers was maximal during the rainy season, mostly concentrated at the top of the water column. Rotifer communities in the riverine source station were different from the open lake communities and rotifer population density was poorest in the riverine section. Significant correlations were found between rotifers and several physico-chemical parameters of which oxygen was the most pronounced. Considerable affinity and close associations were also found to exist between rotifer species.
RCsmCOn a Ctudie les variations saisonnieres, la distribution spatiale et les interrelations des rotiferes du reservoir Opa, au Nigeria, et on a decrit la relation entre des especes de rotiferes et certains parametres physico-chimiques de I'eau. La densite de population des rotiferes etait maximale pendant la saison des pluies, concentree surtout au-dessus de la colonne d'eau. Les communautes de rotiferes a la station proche de la source etaient diffkrentes de celles du lac proprement dit, et la densit6 des populations de rotiferes etait plus faible dans la section riveraine. On a trouvC des correlations significatives entre les rotiferes et plusieurs parametres physico-chimiques, surtout avec I'oxygene. On a aussi dkcouvert qu'il existe des affinitks considkrables et d'etroites associations entre les espkces de ro ti feres.