Changes in the rotifers of Ikpoba River Dam, Benin City, southern Nigeria

Plankton samples were taken fortnightly from the Ikpoba River Dam from February to June 1992 to determine changes in the rotifer community. Fifty-three species of rotifers belonging to thirteen families were identified. One species, Macrochaetus subquadratus of the family Trichotridae was recorded for the first time in Nigeria. In addition to this, eight species, Lecane ohionesis, L. elsa, L. signifera, Keratella lenzi, K. cochlearis, Lepadella cristata, Colurella padulosa and Vonoyella globosa were recorded for the first time in the dam. An important aspect of the changes is in its species composition. The family Lecanidae, was the most abundant in terms of species composition. An entirely new family, Proalidae in the system is the most abundant in terms of abundance. This high number was contributed by only four species. Thus the appearance of new species and the disappearance of existing ones have been an important aspect of the changes in the specific composition of rotifers from what existed in 1982. Key Words: Rotifers, dam, population change, checklist, identification. Tropical Freshwater Biology 11 (2002) 37-4