THE DESCRIPTION AND PRELIMINARY PREDICTION OF THE INUNDATION PATTERN IN A TEMPORARY HABITAT OF ANOSTRACA, NOTOSTRACA AND CONCHOSTRACA IN SOUTH-AFRICA

To explain the life-history strategies of temporary-water fauna, one m ust be able to describe the temporary habitat. It is necessary to know when it will be wet, how often this occurs, for what period each inun dation lasts and what variability there is in this pattern. For logist ic reasons one cannot follow each inundation in a pan for the ten year s or more needed to establish a pattern. Based on the available inunda tion data for two seasons at Bain's Vlei Pan in a semi-arid part of So uth Africa, a model has been developed, using the rainfall pattern ove r ten years at nearby Bloemfontein, to predict inundation. Over a ten- year period predicted inundations ranged up to 87 days as a result of repeat-rain, with a mean period of 18.8 days, while a rain-episode of less than 20 mm was insufficient to inundate the pans. There was an av erage of 5.8 inundations per season. Single inundations do not exceed 20 days due to evaporation. When successive showers fall before period s of inundation are over, a specific extension of inundation is predic table. The precise implications of the inundation pattern on organisms requires much analysis. However, there are strong indications based o n the growth, survival and pattern of egg-production among three speci es (Anostracan - Branchipodopsis tridens, Conchostracan - Leptestherie lla inermis, and Notostracan - Triops granarius) from the pan and one species (Anostracan - Streptocephalus macrourus) from more permanent w aters nearby, that the pattern of inundation is selective of the commu nity held by the pan.