In recent years, the use of seaweed for the bioremediation of aquaculture effluents has increased. Several studies have shown the capacity of nutrient removal of different species of macroalgae and their potential for the integration in aquaculture systems as inorganic dissolved nutrients extractors. In this sense, a research team from China evaluated the nutrient uptake rate and a nutrient reduction efficiency of ammonium and phosphorus from scallop (Chlamys farreri) excretion by the seaweed Gracilaria lemaneiformis cultured in IMTA system in North China. The study was carried out in the Marine Aquaculture Laboratory of Institute of Oceanology., in Qingdao, for three weeks. Four macroalgae density were tested: 69.3 (T1), 139 (T2), 263 (T3) and 347 g m-3 (T4) meanwhile the stock density of scallops was the same in all treatments (409.9 g m-3). At the end of the experiment, the nutrient uptake rate and nutrient reduction efficiency (ammonium and phosphorus) were estimated.

 

Experimental design seaweed and scallops IMTA

IMTA system used in the present study

 

The nutrient uptake rate and nutrient reduction efficiency varied among the macroalgae density. In general, treatments T2, T3, and T4 showed the best nutrient uptake rates. The maximum uptake rate of ammonium and phosphorus was 6.3 and 3.3 μmol g-1 (dry weight) h-1 meanwhile the maximum reduction efficiency of ammonium and phosphorus was 83.7% and 70.4%, respectively. The main conclusion of this study was that the seaweed G. lemaneiformis is a good candidate for the integration in IMTA systems with scallops, the macroalgae were capable of remove most of the ammonium and phosphorus generated by scallops.

For more details see: Mao et al. (2009) Potential of the seaweed Gracilaria lemaneiformis for integrated multi-trophic aquaculture with scallop Chlamys farreri in North China. Journal of Applied Phycology 21, 649-656.