Tswalu Kalahari’s ponds fill of branchiopods

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Temporary water bodies such as everywhere in the arid regions of South Africa. While they may seem devoid of life, researchers have discovered the opposite. Small crustaceans present in these areas have many unique survival techniques, enabling them to persist despite long periods with no water.

Even when water dries up completely these little creatures are able to survive in a dormant state on the soil surface until the rain returns. Eggs can hatch and produce viable offspring after as long as a 20-year dry period.

Twalu Kalahari Reserve

Photo: Jackie Dabrowski

Research teams investigated this phenomenon in the Tswalu Kalahari Reserve and found an incredibly large diversity of clam shrimps, triops and fairy shrimps present in the temporary pools. These branchiopods are incredibly important to the food chain.

“They convert particulate organic matter into protein, turning nutrient-poor waterbodies into nutritious pit-stops for migratory birds,” says Dr Jackie Dabrowski, extraordinary lecturer at the University of Pretoria. Dabrowski said they found a triops species, four fairy shrimp species and three clam shrimp species when they collected samples in hilltop rock pools, muddy pans, and even roadside ditches flooded after rain. They found branchiopods in 80% of the sampled habitats, saying there could be a number of reasons for their absence in some spots.

Rainfall in the region is very patchy, and sites sampled may have received rainfall too recently to have allowed sufficient time for branchiopods to mature and be detected, explains Dabrowski. Another reason for their absence may be they are simply not present because of undirected dispersal, which is dependent on chance factors like the wind.

tadpole shrimp

Photo: Jackie Dabrowski

Some branchiopods have a short life cycle and live for less than 20 days, while those in deeper pools can survive for more than 30 days. “The range of species at Tswalu reflects the wonderful habitat diversity in the reserve. In a sandy place like the Kalahari, rocky outcrops with pools aren’t common, which provides diverse habitat and supports a greater species diversity,” says Dabrowski.

But there might be many more species hiding in Tswalu. “Given that we continued finding new species towards the end of our sampling trip, it is quite likely that additional species occur there,” she says. Hatching studies in the laboratory produced several species that were not observed in the field, and
vice versa.

Dabrowski says there are no thorough distribution records for these creatures in Tswalu, so their research will be able to expand on existing records.

Written by René de Klerk
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