Reproductive capacity of Meristotheca papulosa (Solieriaceae, Rhodophyta) and effects of temperature on carpospore release and sporeling growth

Meristotheca papulosa is an economically important red alga with extensive applications in the food, phycocolloid, and pharmaceutical industries. In Korea, this species has only been observed along the coast of Jeju Island. M. papulosa has been intensively harvested for export throughout history as it is more expensive than other seaweeds, which has substantially decreased its natural resources. To restore the destroyed natural algal populations and meet commercial demands that have continuously increased, we evaluated the reproductive capacity of M. papulosa. Also, the effects of temperature on carpospore release and growth were examined at 16, 18, 20, 22, 24, and 26 degrees C. The reproductive capacity of thalli with cystocarps was higher in August (5.2 x 107 spores m-2). The number of carpospores released from M. papulosa was maximum at 24 degrees C (782 +/- 93 spores cystocarp-1). Temperature also significantly affected sporeling growth and development. Carpospores grew from 17.16 to 159.18 mu m in diameter with maximal growth rate of 10.57% day-1 at 24 degrees C after 21 days. Also, sporelings produced erect thalli at 22-24 degrees C after 28 days. These results provide valuable information for not only the protection and recovery of natural resources but also the establishment of a spore-based cultivation method for this commercially important alga.