Effect of nitrogen and phosphorus addition on the phytoplankton growth in water collected from different trophic regions of lake biwa japan
Ishida, N.; Mitamura, O.
Physiology and Ecology Japan 25(1): 9-18
The importance of nitrogen and phosphorus as factors controlling the production and growth of phytoplankton collected from two different trophic areas in Lake Biwa was assessed by an enrichment experiment. The phytoplankton from the eutrophic area well assimilated ammonia, nitrate and urea during the incubation period, and showed high growth and production. However, no change in growth rate was seen following the addition of phosphorus. Conversely, the addition of phosphorus induced a significant increase in the photosynthetic rate of the phytoplankton from the oligotrophic area, and the addition of a combination of nitrogen and phosphorus stimulated phytoplankton growth more than that of phosphorus alone. The present result suggests that the phytoplankton requirement for nitrogen and phosphorus correlates with the nutrient concentrations in the lake water of each area.