Accumulation of Mycosporine‐like Amino Acids in Asparagopsis armata Grown in Tanks with Fishpond Effluents of Gilthead Sea Bream, Sparus aurata

Abstract

Abstract.— The accumulation of ultraviolet (UV)‐screen substances, mycosporine‐like amino acids (MAAs), in the tetrasporophytic phase of the red alga Asparagopsis armata grown in fishpond effluents of gilthead sea bream, Sparus aurata, is analyzed. Both the effects of total ammonium nitrogen (TAN) fluxes and the algal densities on MAA accumulation were investigated. MAAs increased with the TAN flux, but only until values lower than 100 μM/h. Above this flux, the MAA content decreased, whereas algal yield increased. The content of individual MAAs was related to nitrogen (N) status, that is, shinorine percentage slightly decreased and palythine increased with increasing N fluxes. The decrease of MAAs at high flux of N (up to 100 μM/h) is related to the decrease of water residence time and the decrease of the biofiltration efficiency. Under different TAN fluxes and algal densities, MAA content was negatively related to algal yield indicating that MAAs were accumulated only under a high ammonium‐N availability. Thus, an energy allocation between growth (primary metabolism) and MAA accumulation (secondary metabolism) is regulated by the absorption capacity of inorganic N. In conclusion, A. armata, in addition to its high biofiltration capacity of nutrients, is a good source of MAAs as potential UV screen photoprotectors.