The kinetics of nitrate and ammonia uptake by natural populations of marine phytoplankton

摘要: Abstract The response of natural marine populations phytoplankton to nitrate and ammonia concentrations has been investigated using nitrogen-15 tracer techniques. Experiments made in the Bering Sea, waters southeastern Alaska, northeastern tropical Pacific suggest that uptake both compounds follows Michaelis-Menten expression for enzyme kinetics. A hyperbola, therefore, describes relationship between concentration or nutrient. Such a hyperbola can be obtained easily experiments with and, under suitable conditions, nitrate. value Kt, nutrient at which maximum rate is reduced by one-half, appears related productivity regime region inhabited population. In oligotrophic area investigated, Kt(NO3−) ⩽ 0.2 μg-atom/l., while corresponding eutrophic regions, ⩾ 1.0 μg-atom/l. values regions are adapted low ambient able take up nutrients higher these conditions than would species characteristics showing Kt.