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Natasha Gownaris to Receive Turkana Basin Institute Graduate Fellowship

May 24, 2011

Dr. Lee and students
Natasha Gownaris, Turkana Basin Institute graduate fellow

East Africa’s Turkana Basin is often viewed by anthropologists as the cradle of humankind. Over the decades, the area has produced a wealth of fossils that have helped scientists reconstruct the hominid family tree. However, the interest of Natasha Gownaris in the Turkana Basin region is very much directed towards the future. Natasha is a second year doctoral student at SoMAS’s Institute for Ocean Conservation Science (IOCS). She is interested in how planned hydroelectric development and climate change might impact the fisheries of Lake Turkana and the lives of the people living along the Lake’s margins. Natasha and her academic advisor, Dr. Ellen Pikitch, Executive Director of IOCS, got some very good news recently with word that Natasha had been awarded a graduate fellowship from the Turkana Basin Institute (TBI) to help fund her planned doctoral studies.

“I was drawn to Lake Turkana because of the many knowledge gaps on the ecosystem that, if filled, could assist in better management of its resources in the face of future anthropogenic threats,” said Gownaris. “Successful ecosystem management is crucial to the persistence and productivity of the survival of the fish fauna of the lake, and to the well-being of the wildlife and tribes living on the lake’s shores.”

TBI supports a program of inter-disciplinary scientific research working in affiliation with Stony Brook University, the National Museums of Kenya, the United States International University in Nairobi and others. TBI is a privately funded, non-profit initiative, founded by famed palaeoanthropologist and environmentalist Richard Leakey. Natasha’s $45,000 fellowship will cover three years, with the funds being supplemental to that she is able to secure from other sources.

Dr. Leakey and Dr. Pikitch
Dr. Ellen Pikitch, Institute for Ocean Conservation Science and Dr. Richard Leakey

Lake Turkana is the largest desert, alkaline lake in the world. It supports extensive fisheries, although fish are not a preferred food source of many Lake Turkana tribes and much of the catch from the Lake is sold. It is believed to be the only sustainable source of income for this region and is the main support system for the most vulnerable members of the population, especially women and children. Studying this lake is of interest to Natasha because it may serve as a good model system for predicting the future of other African Great Lakes, given similarities in fish fauna and anthropogenic threats.

“We are very excited for and proud of Natasha for being awarded this prestigious fellowship,” said Dr. Pikitch, who visited Lake Turkana and met with Dr. Leakey in 2010. “Not only will this fellowship greatly benefit Natasha’s knowledge and education in marine conservation, the results of her research can potentially benefit the people and ecosystem of Lake Turkana for years to come.”

Natasha’s proposed research addresses the impacts of climate change and hydroelectric power development on the fisheries of Lake Turkana. The lake is known for large fluctuations in water levels, and the region is already subject to severe drought. Climate change predictions for East Africa suggest fluctuations in the lake’s water levels will become more extreme in the future. Additionally, over 90 percent of the lake’s inflow comes from the Omo River and the inflow is estimated to have already decreased by 50 percent due to upriver irrigation schemes. Two dams have been built along the river and a third dam is being constructed, which may reduce the river’s flow by up to an additional 60 percent. Changes in the amount of water entering Lake Turkana will impact a myriad of factors including the lake’s chemistry, productivity and turbidity and the presence or absence of shallow areas.

Natasha’s research will encompass a suite of field and laboratory studies to help better understand the trophodynamics of the ecosystem, the movement patterns of the fishes within the lake and the tolerance of some of the lake’s fishes to changes in alkalinity and salinity. Her work will be undertaken in close coordination with that of Dr. William Oweke Ojwang, a senior research officer at the Kenya Marine and Fisheries Research Institute.

Stable isotope analyses related to fish diets and trophic positions will be used to develop an understanding of the general trophic structure of the ecosystem and to answer specific questions about the diet of important Lake Turkana fishes. For example, stable carbon isotopes will be used to determine what proportion of the Nile tilapia diet consists of phytoplankton from shallow areas of the lake. These shallow areas have different phytoplankton communities and substantially higher primary productivity rates that the rest of the lake. It is believed that these areas, which will be the first to be impacted by lowered lake levels, are important feeding grounds for Nile tilapia and other fishes. The enhanced understanding of the lake that comes from these results will be used to update a previously developed food-web model of the lake, which can be used by decision-makers and conservationists interested in other aspects of the lake.

Natasha will conduct movement studies involving Nile Tilapia and other fishes of interest. These studies will require catching and tagging Nile tilapia and other fishes and setting up an acoustic receiver array around areas of interest in the lake. The acoustic receivers can be monitored by local fishermen and will continually collect data on the location of the acoustically tagged fishes. This information will help show the amount of time Nile tilapia and other tagged fishes spend in shallow areas of the lake and how their movement patterns relate to the Omo River flood cycle. The acoustic tagging results will enable Natasha to look at the movement of fishes in and out of the lake’s protected areas, which Dr. Ojwang suggests may be seeding the rest of the lake with fishes. If so, the lake’s protected areas may act to increase the resilience of the ecosystem to future anthropogenic impacts. Additionally, Natasha will conduct experimental laboratory trials on the tolerance of Nile tilapia and other Lake Turkana fishes to changes in alkalinity and salinity. Though Nile tilapia is known to be relatively tolerant to increases in salinity, there is little knowledge on the tolerance of tilapia and the lake’s other fish species to changes in alkalinity.

TBI’s primary research focus is human prehistory and related earth and natural science studies within the Lake Turkana Basin. The overriding goal of the TBI graduate fellowship program is to make Turkana Basin research attractive and affordable for the best students in the world interested in this area of research.

 


 

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