Epilithic nitrogen fixation in the rocky littoral zones of Lake Malawi, Africa

摘要

Rates of epilithic N_2 fixation in the rocky littoral zones of Lake Malawi, determined by in situ incubations and the acetylene reduction method, declined with depth, were highly correlated to light intensity and heterocyst biovolume, and are among the highest observed values for freshwater or marine systems. Daytime N_2 fixation rates were similar be- tween sites at similar depths, except at sediment and nutrient impacted sites, where rates were lower and more variable.