Searching for the Source of the Okavango’s Nutrients (SSAWRN)

Alan Anderson

Kelebogile “Kele” Cole entered the RISE program last year with powerful momentum – and from an unlikely background. Her family originated in Sierra Leone, but her grandfather, curious about the outside world, moved to the United States in search of a different life. After his curiosity was satisfied, he returned to Africa, settling in what is now Lesotho. One of his sons, Kele’s father, moved to Botswana, where he met Kele’s mother and settled down to raise his own family. Kele’s nickname is a remnant of that long-ago family foray to the States.

The family stayed in the capital and only major city, Gaborone, which is less than 10 miles from the South African border. (Gaborone, named after a famous Tswana chief, is pronounced ha-ba-ROHN-eh. Locals usually settle for Gabs.) Kele was a bright student, and when it came time for college, the University of Botswana in Gabs was the logical choice. She had already developed a curiosity about how different forms of life could survive in the harsh, dry climate of Southern Africa, and decided to major in ecological studies.

During her studies she took advantage of a workshop on research methods offered by what was then called the Okavango Research Center in Maun, more than 300 miles to the north. She sufficiently impressed her professor, Dr. Caspar Bonyongo, so that he asked her to keep in touch. After graduation, following her own adventurous impulse to see the outside world, Kele went to Russia on an internship sponsored by the International Association for Exchange Students for Technical Experience. She landed a position at the Russian Academy of Sciences’ Institute of Biochemical Physics, helping to make biodegradable plastics.

She did keep in touch with Dr. Bonyongo and learned from him that the RISE program had been announced and that positions might be available to study at Okavango. In September 2009, she was accepted there, first in the capacity of a research assistant, helping with administrative tasks for the new graduate student program – purchasing supplies, processing allowances and student reports. Then in March 2010, Prof. Wellington Masamba invited her to apply to the new RISE program and begin work on a master’s degree. Kele quickly agreed, finding that she could continue her existing job and use her salary to pay for student expenses. Like the other RISE students at what is now (as of October 1) the Okavango Research Institute (ORI), she was assigned to work on an aspect of wetlands research. The Okavango Delta is one of the world’s largest interior wetlands, whose annual flooding from heavy rainfall in the Angolan highlands allows it to support huge numbers of fishes, plants and animals, including the elephants, hippos, leopards, and other large mammals that attract well-heeled tourists.

Only in recent years have scientists, many of them located at or working in partnership with the ORI, begun to study the Delta’s essential basic functions, and Kele was asked to join this effort. She works under the guidance of Drs. Bonyongo and Masamba on the effects of the flooding on nutrient budgets of the soil. The question she is investigating is the following: How can the Delta, swollen each year by flood waters that are poor in essential nutrients, continue to be so productive?

Kele’s field investigations have built on work by other researchers that bears on this question. For example, scientists have found that one source of some nutrients is the wind-blown dust that arrives from the Chobe district to the northeast. However, this dust does not provide nearly enough carbon, nitrogen, phosphorus, and other minerals to support the vast natural wealth of the region. Based again on early work, she is investigating the contributions of two significant components of this ecosystem: (1) decomposed sedges and other vegetation, and (2) mineralized animal dung. “We have a lot of elephants up there,” she said helpfully. “And all of these sources add up.”

She has also investigated the sediment load from the upper “panhandle,” the long, narrow neck of the delta that confines the Angolan flood waters before they begin to spread into the characteristic fan shape of the delta. This water is rich in minerals, especially carbonates, which appear during dry times as the whitish patches or “pans” throughout the region. These and other dissolved minerals make much of the groundwater in Botswana too salty-tasting to drink – even when the floods bring enough water to fill near-surface aquifers. The mineral content also restricts the kinds of plants growing in the delta to the most salt-tolerant species.

After Kele writes up the results of her field work, she will confront the next challenge for young scientists in Africa: finding support for the PhD studies she will need for a career in academia.