Effects of temperature, light level, photoperiod, and ammonium concentration on Pyropia leucosticta (Bangiales, Rhodophyta) from the Northwest Atlantic

Seaweed aquaculture in the Northwest Atlantic is a growing industry that is currently based on winter-spring kelp production. Aquaculture of Pyropia leucosticta , a species of economically valuable nori, could provide a spring-summer crop and diversify the industry. The objectives of this study were to determine the optimum conditions for the production of the foliose blade phase and the conditions for advancement from the microscopic conchocelis to the foliose blade phase of P. leucosticta . Foliose blades were grown under a matrix of temperatures (10, 15, and 20 °C), photoperiods (8:16, 12:12, and 16:8 L:D), and light levels (30, 60, 110, and 250 μmol photons m −2 s −1 ) for a period of 1 month. Free-living conchocelis was grown under a matrix of temperatures (10, 15, and 20 °C), photoperiods (8:16, 12:12, and 16:8 L:D), and ammonium concentrations (20 and 500 μM) for 8–12 weeks. Blades grew optimally at 10 to 15 °C, ≥110 μmol photons m −2 s −1 and ≥12 h of light in the day, with growth rates of over 18 % day −1 recorded. Phycobilin content of blades significantly decreased with increasing day length, while protein content significantly decreased with increasing light level. Conchospore release and germination was observed after approximately 40 days under all tested photoperiods, temperatures, and ammonium concentrations and none of these treatments significantly affected the time until germination. Overall, this study provides important background information required for the establishment of Pyropia leucosticta aquaculture in the Northwest Atlantic.