Faunistics of ephemeral rock pools in southeastern Botswana

Abstract

Abstract: Rock pools on granite outcrops occur worldwide and are poorly studied,despite their intrinsic biological interest. In semi-arid Botswana, such habitats occurmainly on the granite outcrops in the southwestern Hardveld zone. To date, studies onthese systems have focused mainly on individual species or particular interactions. Bymeans of frequent sampling (every other day) during an entire wet phase (hydrocycle),we attempted to get a time integrated overview of invertebrate species composition ina set of 18 rock pools from two clusters (meta-communities).A faunal list is presentedand described. Rock pool species were separated in permanent and ephemeral inhabi-tants, based on their strategy to survive or escape the frequent dry phases of their habi-tat, respectively. A new chydorid species, four new turbellarian taxa and two new ost-racod species were discovered. All new taxa were permanent inhabitants, illustratingthe need for more intense and time-integrated studies of these ephemeral systems andespecially the permanent residents with specific adaptations to the vagaries of theirvariable habitat. The best sampling strategy to assess species richness in these rockpool systems is to randomly sample three to four pools in a cluster, each in the finalphase of their hydrocycle.Key words: rock pool, ephemeral, fauna, sampling.