from WTW® (WTW Wissenschaftlich-Technische Werkstätten
GmbH, Weilheim, Germany). Once a week, 1 day
after the harvests, at 11:00 h, water samples were
taken at the inflows and outflows of the tanks for
TAN analyses. Total ammonia nitrogen (TAN, NH3
+NH4
+
) was determined through the microplate technique
described by Hernández-López and VargasAlbores
(2003). The average reduction in TAN concentration
between the inflows and the outflows of the
tanks (n= 3 for each culture condition) was expressed
as a percentage and defined as nitrogen uptake efficiency
(NUE). The amount of TAN removed per unit
of time per unit of area (mmol m−2 day−1
) by the
seaweeds represented the nitrogen uptake rate (NUR)
and was calculated according to the formula adapted
from Evans and Langdon (2000):