Culture of Nannochloropsis salina in Different Marine Grow Out Effluents

Effluents from different indoor recirculatory marine grow out systems at the Fisheries Harbour Laboratory of Central Marine Fisheries Research Institute, Kochi, were tried as media for culture of Nannochloropsis salina. The experiment was laid out with seven treatments and three replications to arrive at the best medium for growth of Nannochloropsis salina indoors. The treatments tried were commercial grade farm chemicals (0.1g ammonium sulphate + 0.01g super phosphate + 0.01g urea in 1 litre), Walne's medium as well as culture effluents of rotifer (Brachionusplicatilis), clam (Meretrix casta), grouper (Epinephelus tauvina), crab (Scylla tranquebarica) and sea water (control). Nannochloropsis salina inoculum to medium ratio was 1:2. Comparison of the growth among different treatments showed that all media were definitely more productive than seawater. Grouper culture effluent produced highest concentration of Nannochloropsis salina (115 million ml-') followed by Walne's medium (95 million ml-'). The third in performance was rotifer culture effluent which was on par with farm chemicals followed by crab culture effluent which in turn was followed by clam culture effluent. Stationary and declining phase continued till 50th day on which the experiment was terminated. Initial nutrient analyses of media and after 50 days of culture indicated whereever effluents possessed high initial content of NH3-N, more than 95% of it was used up by Nannochloropsis sauna. Grouper culture effluent had lower initial content of NH1-N, out of which 52% was used up by Nannochloropsis salina. In the case of NO3, more than 95% was used by Nannochloropsis salina in all the media tried. Except for Walne's medium, farm chemicals and seawater, more than 90% of NO2 was used by Nannochloropsis salina. Irrespective of the medium used, phosphate utilization was more than 60% in all the cases