Ammonium input to the sea via large sewage outfalls-Part 2: Effects of ammonium on growth and photosynthesis of southern California phytoplankton cultures

Abstract

Cultures of six marine phytoplankton were grown at ammonium concentrations ranging up to 200 μg-atom NH 4N litre −1. Only the growth of dinoflagellates, Gymnodinium splendens and Gonyaulax polyedra was inhibited at the two highest concentrations used. In 3-h photosynthetic 14CO 2 uptake experiments, only Gymnodinium was inhibited at concentrations of NH 4N greater than 100 μg-atom litre −1. We conclude that the increased ammonium concentrations found near Southern California sewage outfalls would not be inhibiting to phytoplankton in the vicinity of such outfalls.