Egg bank of the freshwater systems of Namibia

Abstract

Abstract Temporary water bodies like rock pools and mud pools have specific environmental conditions and are characterised with several short hydration periods in a season. This requires a specific set of life-history adaptations of their permanent inhabitants, which affects species occurrence in the water bodies. In Namibia, large branchiopods are the most abundant species found in these temporal variable environments. Branchiopods like other invertebrates rely on banks of resting eggs to survive long periods of adverse environmental conditions and to buffer against the effects of environmental variability. The eggs usually remain dormant in the dry substrate until the next rain falls. Substrate samples were used to hatch invertebrates, in order to test the viability of using these pre collected samples in invertebrates’ studies. Substrate samples that had been collected from all around Namibia over many years and stored at the Ministry of Agriculture and Water Affairs were hydrated, in order to observe the hatching of invertebrates. Some eggs from the substrate hatched very fast and reached sexually maturity after five day, however some species took longer to hatch or did not hatch at all as they needed more hydration periods or they remained in a diapausing stage for a very long time. Two species of fairy shrimps were identified: Streptocephalidae indistinctus and S. cafer and a clamp shrimp (Leptestheriidae inermis) from different areas. The aim of the study was achieved as samples as old as 13 years yielded some invertebrates, therefore substrate samples can be used for invertebrate studies.