摘要
2009年7月初至2009年9月中旬对烟台长岛县望福礁附近水域鼠尾藻(Sargassum thunbergii)进行了生态学调查。实验设立固定采样地点通过随机采样以及现场标记测量的方法观测了鼠尾藻的生长与生殖情况。结果表明:(1)鼠尾藻生殖始于7月初,8月初为高峰期,此间87%的藻体产生生殖托;(2)藻体长度对成熟比例和生殖力均有显著的影响,藻体成熟具有大小依赖性;(3)营养组织生物量大的鼠尾藻群体生殖组织生物量也相对较大,生殖期间营养组织生长和生殖组织生长呈异速关系;(4)成熟藻体在有性生殖高峰期过后,生长率下降,而始终未成熟的藻体则持续生长(生长率>0)。以上结果表明,在鼠尾藻的生活史中存在着生长与生殖的权衡。
Sargassum thunbergii is a characteristic plant in the rocky intertidal zone along the coast of China, Japan and Korea. This alga plays important roles in the maintenance of a healthy coastal ecosystem due to its large biomass and high productivity. Market demand for this alga is growing because of its high economic value in nutrition, pharmacy and aquaculture. Recently, the cultivation of Stichopus japonicus is rapidly developing in China. As its irreplaceable feed, utilization of S. thunbergii has been increasing, which has resulted in the severely damage of natural resources along the coast of China. Large-scale culture of this alga is the ultimate way for the conservation and sustainable utilization of the resource. Based on an ecological demography conducted from July 2009 to September 2009 in Wangfu Reef, Changdao, Yantai, the resource allocation trade-off between growth and reproduction of S. thunbergii was investigated. Three permanent quadrats at the same depth were set up, of which all thalli in a plot of 30 cm - 30 cm was sampled once a week. Thalli inside the quadrats were randomly removed, bagged, and carried to the laboratory to estimate the relationships between maturation and the length, and the relationships between vegetative and reproductive tissue biomass. At the same time, thirty fertile and thirty sterile thalli were selected to investigate the effects of maturity on growth status, using repeated measures ANOVA. The results showed the following. Reproduction initiated at the beginning of July and peaked at the beginning of August （87% fertile thalli ）. The percentage of fertile thalli exhibited a statistically significant temporal variation. The population investigated in present study is markedly different from those growing on the coast of Pingtan Island, which results from the differences of photoperiod and seawater temperature. Temperature is the critical factor which induced S. thunbergii to translate from vegetative growth to reproduction. During reproduction period, the percentage of fertile individuals had a significant hierarchical variation, and the length of thalli played very important roles in the percentage of fertile tha]li and reproduction effort. Thalli must achieve a critical size before maturation. This suggested the maturation was size-dependent. One underlying assumption in life-history theory is that the trade-off between growth and reproduction can explain this phenomenon： larger plants may take in more resources than smaller ones, which can generate a greater number of reproductive meristems per unit of vegetative biomass. At the peak of fertility, the individuals with greater vegetative biomass were characterized by higher reproductive output, but the different increment speeds between vegetative and reproductive tissue biomass were found. The energy accumulation and growth center varied with growth period indicating that the reproduction meristems growth relies on vegetative tissue and there is a trade-off between reproduction and vegetative growth. Because of partition of resource, senescence and rupture, after the peak of fertility, fertile thalli showed a pronounced negative growth rate while sterile individuals still exhibited a positive growth rate. These results indicate that a trade-off between growth and reproduction exists in the population of S. thunbergii. This life history trait is the result of adjusting to the stressful conditions of intertidal habitats.
出处
《生态学报》
CAS
CSCD
北大核心
2010年第22期6027-6034,共8页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(31070376)
山东省攻关计划(2009GG10005008)
关键词
鼠尾藻
权衡
生殖
大小依赖
生长
Sargassum thunbergii
trade-off
reproduction
size-dependence
growth
