Study On The Early Development Of Tetraspores And Carpospores Of Chondrus Ocellatus Holm (Gigartinaceae, Rhodophyta)

Chondrus is one of the commercial red seaweeds widely used for food and carrageen production. The early development is crucial for the seedling nursing. Natural cycle of the algal life history is well understood, but the properties of development of tetraspore and carpospore are still very poorly known. It is therefore necessary to understand the physiological influences on its early development. Here in our study, the thalli of C. ocellatus Holm were collected from the natural habitants in Qingdao, China, from Oct. to Dec. 2008. The effects of temperature and irradiance on the early development of C. ocellatus tetraspores and carpospores under laboratory conditions were conducted, and meanwhile the properties of development process was observed and recorded. It is showed that there are no obvious differences existing between the early development of tetraspores and carpospores, and the development can be regarded as three stages: division stage, discoid crust stage and seedling stage. Besides, the coalescences of two or three discoid crusts during the early development were observed, which enhanced the adhesion of sporelings to the substrates. The released tetraspores and carpospores were cultivated at 6 different temperatures (10°C, 15°C, 20°C, 22°C, 25°C, 28°C) and two irradiances (10, 60μmol photos m-2s-1) with a photoperiod of 12:12h (L:D). It was showed that the optimal temperature suitable to the early development of C. ocellatus Holm is 20°C, and a maximum growth rate occurred above 60μmol photos m-2s-1. Both tetraspores and carpospores showed a wide tolerance to temperature from 10-25°C, but too high temperature of 28°C will lead to the death of tetraspore and carpospore. According to statistic analysis by means of one-way ANOVA and independent-samples t test, the variations of temperature and irradiance significantly affected discoid crust growth. High light intensity significantly accelerated growth and development. Low temperature of 10°C retarded the growth and development.