A preliminary comparison of the mariculture potential of Porphyra purpurea and Porphyra umbilicalis

Due to their rapid growth and nutrient assimilation, Porphyra spp. are good candidates for bioremediation and polyculture. The production potential of two strains of P. purpurea and P. umbilicalis from north-east USA was evaluated by measuring rates of photosynthesis (as O-2 evolution) of material grown at 20 degrees C. Photosynthetic rates of P. umbilicalis were 80% higher than P. purpurea over the temperature range 5-20 degrees C, at both sub-saturating and saturating irradiances (37 and 289 mu mol photon m(-2) s(-1)). Porphyra umbilicalis was more efficient at low irradiances (higher alpha) and had a higher P-max (23.0 vs 15.6 mu mol O-2 g(-1) DW min(-1)) than P. purpurea, suggesting that P. umbilicalis is a better choice for mass culture, where self-shading may be severe.