| Scytosiphon lomentaria (Lyngbye.) Link which belongs to Phaeophyta, distributes from the Arctic Ocean to southern coast of Australia. In China, it is widely distributed from southern coastal areas to northern coastal areas, and it usually grows on bedrocks or stones of middle and low tide region. Its color is tawny to dark brown, and the gametophyte is erect, single, cluster, tubular, plumpness in the young gametophyte, but late grows into cylindrical form with constriction. The length of the mature thallus is 40-150cm.S. lomentaria has a very high edible value, since it is full of nutrients and has a special and delicious taste. At the same time, S. lomentaria has a very high medical value, for it shows high activity in antioxidant, antitumor, antivirus and antibacteria. Besides,5. lomentaria as a kind of high quality macroscopic algae, also has a high ecological value, which can absorb a lot of the excess nitrogen and phosphorus in seawater, and reduce the degree of eutrophication of seawater.S. lomentaria has a life cycle of alternation of heteromorphic generations. Its sporophytic filaments, cushion-like and crustose thalli are the objects of germplasm preservation and germplasm amplification, and the erect gametophytic thallus is the object of cultivation. The spores, which are released by sporophytes of S. lomentaria, grow and develop into mature thallus after attachment and germination. However, during spore attachment, germination and the early development of sporelings, S. lomentaria is greatly influenced by biological factors such as epiphytic algae, and non-biological factors such as temperature, light intensity, and so on. Thus, on the basis of understanding the life history and biological characteristics of S. lomentaria, this paper is mainly focused on the effects of environmental factors on spore attachment, germination, early development of the sporelings of S. lomentaria and the dynamic change of epiphytic algae, which would lay a theoretical foundation on reproductive biology of S. lomentaria and provide technical support on breeding of S. lomentaria.The results of this thesis were as follows:1. On the basis of application of experimental ecology methods, the filaments of S. lomentaria and the natural seawater were used as the experimental material and the culture solution respectively. Effects of different types of seawater such as natural seawater, natural seawater filtered with absorbent cotton and aseptic seawater, and the environmental factors such as temperature, salinity, pH and light intensity, on spore attachment of S. lomentaria were studied. At the same time, the phototaxis of the spores of S. lomentaria was also studied. The results indicated that:(1) Different types of seawater have significant influence on spore attachment of S. lomentaria, and the natural seawater filtered with absorbent cotton is the most suitable for spore attachment of S. lomentaria. (2) 12.0-22.0℃ is the appropriate temperature range for spore attachment of S. lomentaria, and the optimum temperature is 17.0℃. When the temperature of seawater go below or exceed 17.0℃, the density of attached spore would be significantly reduced. (3) 26-34 was the suitable salinity range for spore attachment of S. lomentaria, and the optimal salinity is 30. (4) 8.0-8.5 is the appropriate pH range for spore attachment of S. lomentaria, and the optimal pH is 8.5. (5) The light intensity is not the necessary condition for spore attachment of 5. lomentaria. No matter in dark or light, the spore of S. lomentaria would attach on the coverslip successfully, and the density of attached spore in dark or light is no significant difference. (6) When the light intensity≤45.0μmol/(m2 s), the spore of S. lomentaria most probably swim to the direction of light source and attach on the coverslip which near the light source. However, when the light intensity ≥63.0μmol/(m2·s), the spore of S. lomentaria would mainly swim away the direction of light source and attach in the low light intensity areas.2. By imitating the culture conditions of sporelings of 5. lomentaria, the filaments of S. lomentaria and the natural seawater filtered with sand were used as the experimental material and the culture solution respectively. Different light intensities were set to study the effect of light intensity on spore germination, early development of sporelings of S. lomentaria and the dynamic change of epiphytic algae. The results indicated that:(1) 27.0-72.0μmol/(m2·s) is the appropriate light intensity range for the spore germination of S. lomentaria, and the germination rate reached the maximum under the condition of 45.0μmol/(m2·s), which was (44.44±5.50)% after 16 days of the spores releasing. (2)In the natural seawater filtered by sand, 36.0-54.0μmol/(m2·s) was the appropriate light intensity range for the early development of sporelings, and the optimal light intensity was 45.0μmol/(m2·s), under which condition the density of epiphytic algae was the lowest and reached (38.4±0.6)×104ind/cm2 after 34 days of the spores releasing. (3)In this study, a total of 29 taxa which belong to 13 genera of 2 phyla were identified, and the main dominant species were Nitzschia frustulum, Pseudo-Nitzschia sicula, Oscillatoria laetevirens, Chroococcus turgidus, Auricula Castracane sp. and Nitzschia closterium. Nitzschia frustulum showed exponential growth trend under the condition of 7.2-18μmol/(m2·s), while Auricula sp. and Nitzschia closterium presented exponential growth trend under the condition of 27.0～126.0μmol/(m2·s).3. By imitating the culture conditions of sporelings of S. lomentaria, the filaments of S. lomentaria and the natural seawater were used as the experimental material and the culture solution respectively. Different temperatures were set to study the effect of temperature on spore germination, early development of sporelings of S. lomentaria and the dynamic change of epiphytic algae. The results indicated that:(1) In natural seawater,6.0-12.0℃ is the optimal temperature range for spore germination of S. lomentaria, and the germination rates of spore are not significant difference in these temperature conditions. (2) In natural seawater,6.0…12.0℃ is the suitable temperature range for early development of sporelings of S. lomentaria. The optimal temperature for early development of sporelings of S. lomentaria is 12℃, in which the density of epiphytic algae is the lowest. However, when the temperature exceed 12℃, large numbers of the sporelings of S. lomentaria and the epiphytic algae would die. (3) In this study, a total of 35 taxa which belong to 19 genera of 2 phyla were identified, and the main dominant species was Nitzschia frustulum, and the density of epiphytic algae increases with the rise of temperature. |
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