Population dynamics of planktonic rotifers in Balloki Headworks.

Abstract

The population dynamics of rotifers were determined in Balloki Head Works (Pakistan) by tracking monthly variations in diversity and population density. A total of 38 rotifer species belonging to 20 genera and 13 families were identified from the three study areas. Twenty four species were new records for Pakistan. Three families dominated (Brachionidae, Lecanidae and Trichocercidae), with Brachionus, Lecane and Trichocerca, respectively, being the most important genera. The impact of physico-chemical parameters on population dynamics of rotifers were similar for the three study areas. Rotifer density was positively correlated with water temperature, being the highest in summer and the lowest in autumn/winter. Conductivity also had positive correlation with rotifer density. Negative correlation was however observed with pH, dissolved oxygen, and total hardness. Rotifers of the two lotic habitats showed positive correlation with water flow while rotifer diversity was very low as compared to that found in the lentic habitat. Analysis of variance of the three study areas indicated that DO (F=3.80, p=0.033), and conductivity (F=5.23, p=0.011) were statistically significant (=0.05), while water temperature (F=0.06, p=0.946), pH (F= 0.09, p=0.919) and total hardness (F=0.39, p=0.682) were non-significant..