Fluctuations in some hydrological factors and the condition index of Aspatharia sinuata (Bivalvia: Unionacea)in a small Nigerian reservoir
The relationship between the fluctuations in some environmental factors and the tissue condition ol the tropical bivalve, Aspatharia sinuata occurring in a small. Nigerian man-made lake has been investigated. The condition index (meat : shell ratio) ot the bivalves was high in December—May when the water was generally characterized by high temperatures, low silt content, high calcium and dissolved oxygen concentrations. high conductivities, and neutral/alkaline conditions. In June—November, the index was low and this seemed related to the slightly reduced temperatures, high silt content, low calcium and oxygen concentrations, low- conductivities, and acid waters which occurred for most part of the interval. Personal observations indicate that reproductive activity may have placed a less significant role in determining the pattern of changes in the condition
index of the population, presumably because they maintained a high gonadal activity throughout the year.