实验海洋生物学重点实验室知识库

海带是我国最重要的经济褐藻，对我国海藻养殖业具有重要意义。开展海带繁殖与栽培方面的研究，了解并掌握它们孢子囊形成、种苗培育、假根附着的特点和规律，追溯养殖过程中遇到的有害藻类—漂浮铜藻的来源，对指导我们提高种苗培育和养殖技术，解决实际生产中的科学问题具有重要的意义。

论文分为四部分，具体研究内容和结果如下：

1）关于杂交海带新品系不能在大规模育苗期形成孢子囊原因的研究。为了弄清杂交海带B013受精时间和孢子囊形成的关系，使配子体分别在2014年5、6、7、8月份受精，并在旅顺海区养殖，在2015年9月份结束。检查发现，5月份受精的100%，8月份受精的80%于2015年1月份在海带尖端形成孢子囊（宽：6cm，长：50cm）。在2015年8月份（孢子囊形成期）都没有形成孢子囊，直到9月份才形成。结果表明，延长海带生长期不能促使杂交海带在育苗期形成孢子囊，孢子囊的成熟与海带生长期的长短不相关。

2）海带夏苗培育中营养盐添加方式优化的研究。本次对育苗生产过程的研究是在大连旅顺一育苗场进行，包括：对种海带的选择，对游孢子释放的控制，对不同育苗期光线、温度、营养盐的调节和控制。结果表明，海带苗对N、P的吸收并不是传统认为的1:0.1，而是低于这个比值。基于此研究结果，在原有海带夏苗培育技术的基础上，优化了氮、磷的添加比例，满足了海带苗对营养盐的需求，取得了育苗的成功。

3）成体海带脱菜问题的研究。为了弄清脱菜原因，于2016~2017年海带收割期对不同根型，不同品种，不同养殖区的海带进行了调查，同时在实验室做了相关的培养实验。结果表明，合适的夹苗密度并根据海水透明度适时调整水深能有效降低脱菜率，并且培育新的海带品种是从根本上降低脱菜的有效措施。

4）海带养殖过程中的危害藻类—漂浮铜藻的来源问题研究。本研究利用高多态性微卫星（SSR）标记对黄东海13个代表性漂浮种群和3个代表性定生种群遗传结构和亲缘关系进行了分析，结果显示：相同年份漂浮铜藻的亲缘关系相近，而不同年份差异显著；（2）有的同一漂浮种群内部也存在遗传分化的现象。因此推测不同年份的漂浮铜藻起源于不同的地点，同一漂浮种群的个体也可能源自不同地点。东黄海漂浮铜藻总体呈现多个起源的特点。

Saccharina japonica is one of the most important economic seaweeds in China and of great significance for farming industry. Study on crucial reproduction and  cultivation problems which are involved in variety breeding of S. japonica such as sorus formation, seedling production, ability of haptera attachment and the handling of the harmful seaweed—Sargassum horneri can help us improve the breeding technology and increase the efficiency of farming process.

The thesis includes four parts as follows:

1) Study on sorus formation of the hybrid cultivar B013 during the large scale production of seedling period. In order to understand the relationship between the timing of crossing of the parental gametophytes and sporogenesis of their sporophyte offspring in cultivar B013, we crossed the parental gametophytes for four times in May, June, July and August in 2014 respectively and performed open-sea cultivation at Lvshun, Dalian in surface water until September of 2015. Results showed that 100% of the May group and 80% of the June group formed 6-cm wide and 50-cm long sori in the apical one-third zone of the blade for the first time in the mid of January. No sorus formed in August group until September. These results suggest that there are no clear co-relations between timing of fertilization and sporogenesis in the cultivar B013. Prolonging growth period is useless to induce timely sorus formation in B013.

2) Study on the optimization of the nutrient addation during the “summer-sporeling” production. In this case study, the entire process of a commercial hatchery manipulation in 2015’s production season at Lvshun, Dalian, northern China is presented, including pre-treatment of parental plants, control of spore release, control and adjustment of solar irradiance and temperature at different developmental stages of the plants as well as the nutrient supply regime over the entire course. These results suggest that emerged sporophytes on the string requires more P during the entire process and constant supply of sufficient nutrients day and night. According to the data and process in this report, we make an optimization of the “summer-sporeling” which proved useful for husbandry of seedlings.

3) Study on the overhigh problem of detachment of the adult sporophytes. To elucidate the reason, hapteras of the individually farmed plants from different cultivars were checked on longline in the production season of 2016-2017. In the mean times, culture experiments were carried out in indoor flow-through tanks so as to make us understand how haptera of this species develops on substrate. It is recommended that proper plant density on rope and timely adjustment according to water transparency be implemented in farming practice. But for the long run, cultivar improvement is the essential issue that should be focused.

4) Study on origin of the drifting harmful algae— Sargassum horneri on the kelp culture system. In this study, 16 populations including 3 benthic ones and 13 drifting ones were collected from The Yellow Sea and East China Sea. They were investigated using SSR (Microsatellite or Simple Sequence Repeat) markers. Cluster analysis showed that in general the drifting populations from the same year rather than from the similar location were clustered together. The existence of marked admixture in six populations also implies that the same drifting population could be of different origins. These results provide evidence suggesting that the drifting populations along the nearshore waters of China, in particular the populations occurring in different years, were originated from multiple sources.