Photosynthetic rates of phytoplankton in East African alkaline, saline lake?

Abstract

Photosynthetic rates were calculated in six myxophycean-dominated alkaline, saline lakes in Kenya and Tanzania from changes in dissolved O2 in light and dark bottles and from diurnal variations in dissolved 02. Rates of gross photosynthesis are exceptionally high for Lake Nakuru, Kenya, by the diurnal free-water technique (e.g. 36 g 0, m-’ day-l). Gross photosynthesis in Lake Nakuru was compjred for two consecutive days: on the first day pronounced thermal stratification developed and the dissolved 02 reached 340% saturation in the upper half meter; on the second day wind-driven turbulence circulated the algae to depths often greater than 2 m in water with Secchi disk visibility of only 15 cm. Because of analytical difficulties in measuring dissolved 02 in soda lakes, laboratory experiments were conducted to determine the reliability of the titrimetric (Winkler, Miller), gasometric ( Scholandcr), and polarographic (oxygen probe) methods. The polarographic technique was the most suitable for determinations of dissolved O2 in the field.