DURATION OF INUNDATION AND CHANGE IN PHYSICAL AND CHEMICAL CHARACTERISTICS OF SMALL TEMPORARY PANS IN SOUTH-AFRICA

The day-to-day fluctuations in water depth, water temperature, dissolv ed oxygen concentration, pH, conductivity and turbidity of six pans at Bain's Vlei, South Africa, were monitored during five successive inun dations from September 1988 to April 1989. Mean duration of inundation s was 13.9 days, daytime water temperatures ranged from 10.5-degrees-C -33.1-degrees-C, dissolved oxygen ranged from 30% to 142% saturation a nd conductivity ranged from 43-2630 muS cm-1. F-test multivariate anal ysis indicated that physical and chemical characteristics of all pans were similar during the first inundation but differed significantly du ring the subsequent inundations. The aquatic pan environment is epheme ral, fluctuating and unpredictable. The biological community should co nsequently feature adaptations to these conditions.