Dr Betsie Milne from the Arid Lands Node swapped her office in hot Kimberley for three months at the end of 2019 to undertake extensive lab work at one of the top universities in Europe.

International collaboration

The Katholieke Universiteit Leuven (KU Leuven) awarded me a GLOBAL MINDS: Short Term Research Stay Mobility Grant, which gave me the opportunity to work at the Laboratory of Aquatic Ecology, Evolution and Conservation under the mentorship of Professor Luc Brendonck and Dr Tom Pinceel.

I have been studying the ecology of branchiopods in very unique temporary wetlands (commonly known as pans) of the Northern Cape for the past three years. This research is an attempt to establish baseline biodiversity information that can direct land managers and decision-makers regarding the development, conservation and monitoring of these long neglected aquatic ecosystems. However, key elements pertaining to my understanding of the biodiversity in these systems could not yet be comprehensively analysed, mainly due to a lack of suitable infrastructure and associated expertise in South Africa.

I met Prof Brendonck at the Annual Wetlands Indaba Conference held in Kimberley during 2018. We subsequently identified significant scope for collaboration.

Prof Brendonck is a temporary wetland expert, renowned for his research on large branchiopods, and has extensive knowledge of wetland ecology and conservation, especially in (semi-) arid regions. His lab offered vital infrastructure to improve my understanding of the ecology of the Northern Cape pans.

Extensive laboratory protocols

I spent most of my days in a medieval cellar built in the early 1400s. For perspective, this was before Portuguese navigator Bartolomeu Dias treaded South African soil in 1480, and two centuries before Jan van Riebeeck arrived in the Cape. Today, it has been converted into a laboratory for aquatic science where world-renowned research on damselfly larvae, large branchiopods, Daphnia and Killifish are being undertaken.

Normally, wetlands are sampled when wet in order to obtain “live” information about their biodiversity and habitat conditions. However, due to the arid climate and the sporadic rainfall patterns in the Northern Cape, it is not always possible to obtain this information over a large spatial scale.

I was only able to sample 16 wet pans over a three-year period, which is not sufficient for robust scientific analyses. As an alternative, I collected soil samples from 98 desiccated pans across the pan hotspot regions (Kalahari, Bushmanland, Upper Karoo and Ghaap Plateau) of the Northern Cape to enable me to perform extensive laboratory protocols during my time at KU Leuven.

I undertook extensive hatching experiments in high-tech incubators with soils collected from each study pan in the Northern Cape to obtain biodiversity information. Branchiopods are highly sensitive to specific habitat conditions. Therefore, I also took basic water quality measurements from each sample and performed nutrient analyses (Phosphorus and Nitrogen) to understand species-specific habitat preferences and hatching cues.

I had to continuously monitor each hatching container to extract any hatchlings of the predatory tadpole shrimp (Triops granarius). All other hatchlings were raised to maturity before I extracted and preserved them for later taxonomic determinations. I was able to perform a total of 196 hatching experiments over a period of 65 days, with a 76% success rate.

I also performed extensive egg bank analyses through microscopy to supplement the biodiversity data obtained from hatching experiments and live sampling. Branchiopods are specially adapted to survive periods of prolonged drought through the production of dormant eggs that are contained in the top 5 cm of the soil layer.

Each branchiopod species also has unique egg morphology. Therefore, by extracting the eggs from the soil and then sorting them into distinct morphological groups using microscopy, I could obtain supplementary species information. I sorted through 196 egg bank samples, separating over 3 500 eggs, which produced species information for 88% of the study sites.

Due to the small size (1mm) of these eggs, each reference egg was photographed using a scanning electron microscope (SEM). A total of 36 reference eggs were photographed using SEM. This was performed by Alexander Vrijdagh from the KU Leuven Institute of Botany and Microbiology.

Through these analyses my data sets were significantly improved, with only eight study sites not producing any species information. Water quality measurements taken from each sample will aid in understanding why hatching was inhibited in the unsuccessful hatching attempts and could also shed light on egg bank deficiencies.