MohammadReza Fatemi - Department of Marine Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
Yousef Filizadeh - Department of Agronomy, Shahed University, Tehran, Iran
Farzaneh Rafiee - Department of Marine Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
Behnam Daghoghi - Fisheries Research Center of Bandar Abbas, Iran
GholamReza Arganji - Research Station of Mollusks of Persian Gulf, Bandar Lengeh, Iran
Hossein Rameshi - Research Station of Mollusks of Persian Gulf, Bandar Lengeh, Iran
Iraj Rajabi - Research Station of Mollusks of Persian Gulf, Bandar Lengeh, Iran

The effects of some environmental parameterson biomass and agar yield of Gracilariacorticatawere examined under laboratoryconditions. The macroalga was collected fromnatural tidal pool with in Bostaneh coast (thePersian Gulf) in May ۲۰۰۴. In the laboratory,biomass and agar yield were measured after ۴۵days examining effect of different temperatures(۲۴, ۲۷ and ۳۲°C), photon irradiances (۲۴, ۶۶and ۹۴ photons m-۲s-۱), and concentrations ofammonium phosphate [unenriched seawater(۰), ۰.۰۴ and ۰.۰۸gl-۱] in culture. Except forconcentration of ammonium phosphate, otherenvironmental variables showed no significantrelationship (P>۰.۰۵) with biomass and agarcontent of G. corticata. The agar yield derivedfrom the alga cultivated at ۰.۰۸gl-۱ ammoniumphosphate (۲۲.۴۰±۱.۸۱%) was significantlygreater than the other treatments that makes G.corticata one of the commercial agarophytes(p<۰.۰۵).

Keywords: Biomass, Temperature, Irradiance, Gracilaria corticata, Ammonium phosphate, Agar