Growth and agar quality of Gracilaria heteroclada (Zhang et Xia) grown in a filter tank

Abstract

Gracilaria heteroclada Zhang et Xia was grown in filter tanks to determine the growth, agar quality and uptake pattern of nitrogen and to observe the water quality in recirculating water system with seaweed.

Rapid uptake of nitrogen in G. heteroclada was observed within the first 24th of culture. Filling up of the nitrogen pools in the cell may have continued until the fifth day, the plants started to increase in weight, proportionate to the uptake rate of nitrogen duing the experiment. G. heteroclada stocked at 1 kg m^-2achieved a specific growth rate (SGR) of approximately 10.4% d^-1 during 15d of culture, at total ammonia-nitrogen and nitrite-nitrogen levels of 0.03-0.27 mg L^-1 and 0.04-0.19mg L^-1, respectively, in the filter tank. Approximately 11% of nitrogen in the water was removed by the seaweed.