Bio

Dr. OLAKA, Lydia Atieno

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Publications


2014

2012

Stoof-Leichsenring, KR, Junginger A, Olaka LA, Tiedemann R, Trauth MH.  2012.  Natural environmental variability and anthropogenic overprint in the Lake Naivasha Basin Central Kenya Rift: A diatom record over the last two centuries. AbstractNatural environmental variability and anthropogenic overprint in the Lake Naivasha Basin Central Kenya Rift: A diatom record ove

Lake Naivasha, Kenya, is one of a number of freshwater lakes in the East African Rift System. Since the beginning of the twentieth century, it has experienced greater anthropogenic influence as a result of increasingly intensive farming of coffee, tea, flowers, and other horticultural crops within its catchment. The water-level history of Lake Naivasha over the past 200years was derived from a combination of instrumental records and sediment data. In this study, we analysed diatoms in a lake sediment core to infer past lacustrine conductivity and total phosphorus concentrations. We also measured total nitrogen and carbon concentrations in the sediments. Core chronology was established by 210Pb dating and covered a ~186-year history of natural (climatic) and human-induced environmental changes. Three stratigraphic zones in the core were identified using diatom assemblages. There was a change from littoral/epiphytic diatoms such as Gomphonema gracile and Cymbella muelleri, which occurred during a prolonged dry period from ca. 1820 to 1896 AD, through a transition period, to the present planktonic Aulacoseira sp. that favors nutrient-rich waters. This marked change in the diatom assemblage was caused by climate change, and later a strong anthropogenic overprint on the lake system. Increases in sediment accumulation rates since 1928, from 0.01 to 0.08gcm−2year−1 correlate with an increase in diatom-inferred total phosphorus concentrations since the beginning of the twentieth century. The increase in phosphorus accumulation suggests increasing eutrophication of freshwater Lake Naivasha. This study identified two major periods in the lake’s history: (1) the period from 1820 to 1950 AD, during which the lake was affected mainly by natural climate variations, and (2) the period since 1950, during which the effects of anthropogenic activity overprinted those of natural climate variation.

2011

Stoof, KR, Junginger A, Olaka LA, Tiedemann R, Trauth MH.  2011.  Natural environmental variability and anthropogenic overprint in the Lake Naivasha Basin Central Kenya Rift: A diatom record over the last two centuries. Journal of Paleolimnology. 45:353-367.

2010

Trauth, MH, Maslin MA, Deino A, Junginger A, Lesoloyia M, EO O, Olago DO, Olaka L, Strecker MR.  2010.  Human evolution in a variable environment: The amplifier lakes of Eastern Africa.
Olaka, LA, Odada EO, Trauth MH, Olago DO.  2010.  The Sensitivity of East African rift lakes to climate fluctuations. Journal of Paleolimnology. 44:629-644.

2007

Olago, D, Marshall M, Wandiga SO, Opondo M, Yanda PZ, Kangalawe R, Githeko A, Downs T, Opere A, Kabumbuli R, Kirumira E, Ogallo L, Mugambi P, Apindi E, Githui F, Kathuri J, Olaka L, Sigalla R, Nanyunja R, Baguma T, Achola P.  2007.  Climatic Socio-economic and Health Factors Affecting Human Vulnerability to Cholera in the Lake Victoria Basin East Africa. AMBIO: A Journal of the Human Environment. 36:350–358.

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