The effects of nitrogen and seawater flow rate on the growth and biochemical composition of Gracilaria foliifera var. angustissima in mass outdoor cultures

The effects of nitrogen species (NH4+ N and NO3- N), loading (m moles of N/day) and seawater flow rate on the growth
of the red seaweed Gracilaria foliifera var. angustissima (Harvey) Taylor were investigated in outdoor culture tanks.
In one experiment, cultures received seawater enriched with either NH4+, NO3- or secondarily treated wastewater (with
N as NO3-) but the same daily nitrogen load at four seawater turnover rates (1, 7.5, 15 and 30 culture volume exchanges/
day). In another experiment, cultures were maintained at four turnover rates (1, 7.5, 15 and 30 culture
volume exchanges/day) with NH4+ or NO3- at a given concentration so that nitrogen loading was proportinal to turnover
rate.