NITRATE UPTAKE BY ENTEROMORPHA SPP (CHLOROPHYCEAE) - APPLICATIONS TO AQUACULTURE SYSTEMS

Enteromorpha linza and E. intestinalis thrive in aquatic systems rich in inorganic fixed nitrogen. At 15°C and ca. 1800 μW cm-2 these algae showed a Vmax for nitrate uptake of 129 μmol h- g-1 dry weight ( = ca. 22 μmol h-1 g-1 wet weight) and a Ks of 17 μM. At 20 μM rates averaged 70 ± 21 μmol h-1 g-1. They dropped to 19% of this value at 5°C, and at 0°C nitrate uptake ceased. In the first hour of darkness, nitrate uptake decreased to 35% and in the second hour to 10% of the rate in light. Enteromorpha spp. scavenged nitrate from the medium at concentrations < 0.5 μM, and no nitrate leaked out of the tissue into nitrate-free water. Information from this study may be useful in designing nutrient feeding strategies in aquaculture systems. © 1978.