Page 79 - University of Pretoria RESEARCH REVIEW 2016

There is much more to do, and many important questions remain to be answered. For example, the role of bacteriophage and viruses in desert soils is completely unknown. These ‘organisms’ are critically important in controlling host population sizes (such as ‘algal blooms’) in aquatic ecosystems, but Professor Cowan and his colleagues have hypothesised that their role in desert soil ecosystem dynamics may be much less – since the absence of water limits the viruses’ capacity to move from one part of the community to another. Little is known about process rates: how much atmospheric nitrogen do desert microorganisms fix into the soil, and how quickly do the specialised hypolithic communities (green biofilms living on the undersides of translucent quartz rocks embedded in the desert pavement) actually grow. CMEG researchers have set up a special field experiment to measure this rate. Professor Cowan notes that they hope to have an answer by 2020.
TEAM EFFORT
Each year for the past seven years, Professor Don Cowan, along with colleagues from the University of the Western Cape (Professor Marla Trindade) and the University of Cape Town (Professor Ed Rybicki), has organised and hosted a field expedition to the Gobabeb Research and Training Centre in the central Namib Desert. Situated on the banks of the (mostly dry) Kuiseb River, the Gobabeb field station has superb access to both the northern gravel deserts and the southern sand-dune (‘sand sea’). Working in close collaboration with the Centre’s Director, Gillian Maggs-Kölling, and legendary ex-Director Mary Seely, Professor Cowan’s approach has been to gather a team of national and international researchers with complementary interests in the many aspects of desert soil ecology. Thirty-five scientists participated in the week-long field expedition in April 2016.
In their seven years of work in the Namib Desert, Professor Cowan has hosted 41 CMEG members, and over 60 visitors from other South African, African and other continental universities. Several collaborative research programmes have developed from these visits: for example, on soil respiration processes; plant rhizosheaths (a specialised adaptation of desert plants, which involves a sheath of mineral particle and bacteria around the roots); the spatial aspects of Fairy Circles (see Ramond article on page 79) and desert hypolithic biology; the quartz surface microenvironment of hypolithic bacteria; and unravelling the extraordinary genetic complexity of previously unknown species of Namib Desert springtails.
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