2015年以来，秦皇岛近岸海域暴发了绿潮，对北戴河旅游区的环境和生态系统造成了严重影响。绿藻微观繁殖体在绿潮的形成过程中起到重要作用，主要包括孢子、配子、幼苗和营养片段。绿藻微观繁殖体作为绿潮的“种源”，其分布规律可以反映绿潮的“藻源”位置。本研究于2016年4-9月和2017年1月对秦皇岛近岸海域绿藻微观繁殖体的调查，探究了其分布规律以及生物量变化。结果显示，绿藻微观繁殖体主要分布在近岸海域，由近岸向远岸海域逐渐降低。绿藻微观繁殖体的数量在7、8月份最高，在冬季最低。受绿潮影响严重的海域微观繁殖体数量高于其它海域。秦皇岛近岸海域的绿藻微观繁殖体为该海域绿潮的种源，其分布规律表明秦皇岛近岸海域绿潮起源于本地。

Since 2015, green tides have been blooming in offshore waters of Qinhuangdao, with serious impacts on the local ecological environment and tourism. Ulva australis, Bryopsis plumosa, and U. prolifera are the dominant species of Qinhuangdao green tides, following a sequential succession pattern. Ulva prolifera is the dominant species, with the highest biomass and the greatest influence on the local ecological environment. To study the reason of green tide dominant species succession and U. profilera became the dominant species with the largest biomass, we compared and analyzed the growth and nutrient uptake capacity of the three algae. The results showed that temperature significantly affects the growth of the three species. Within the temperature range of the experimental setup, the optimum temperature for the growth of U. australis, B. plumosa andU. profilera is 10℃, 15℃, and 20–25℃, respectively. Combined with the temperature variation trend during green tide bloom development, we believe that temperature is the key environmental factor for the succession of the dominant species. Ulva prolifera has a higher growth rate than U. australisand B. plumosa under the same nitrate, ammonium, and phosphate levels. Significant differences in the maximum absorption rate (R_max) and R_max/K_s (the relationship between uptake rate and substrate concentration) values indicated that U. prolifera had an apparent competitive advantage over U. australis and B. plumosa regarding nutrient uptake. Therefore, the strong growth and nutrient uptake capacities of U. prolifera might be the main reason for becoming the dominant species with the largest biomass in Qinhuangdao green tides.

Since 2015, green tides with Ulva prolifera as the dominant species in the Qinhuangdao coastal waters have continued to occur. In this study, the relationship between green tides in Qinhuangdao and the Yellow Sea (setting sites in Rudong and Qingdao) was evaluated by genetic analyses of U. prolifera. Single nucleotide polymorphism (SNP) markers were used to analyze genetic diversity and genetic relationships among groups. Genetic differentiation was lower among floating U. prolifera populations in Rudong and Qingdao than in Qinhuangdao. The floating U. prolifera population had higher genetic diversity and polymorphism levels in Qingdao and Rudong than in Qinhuangdao. Physiological experiments showed that the growth rate and net buoyancy of floating U. prolifera were highest in Qinhuangdao and Qingdao, respectively, under the same environmental conditions (temperature and light). Overall, these findings showed that U. prolifera populations in the Qinhuangdao and Yellow Sea green tides (Rudong and Qingdao) differ significantly at the molecular and physiological levels. Therefore, the Qinhuangdao green tide is not correlated with the Yellow Sea green tide and has a different origin and development mode. This study provides insight into the mechanism underlying green tide blooms in coastal waters of China.

近年来,秦皇岛近岸海域连续发生抑食金球藻褐潮,对当地贝类水产养殖带来负面影响.由于其个体及其微小,在光学显微镜下很难将抑食金球藻和水体中其他微型藻类准确区分.基于18S rDNA 序列,本研究应用实时定量PCR技术检测和计数环境中的抑食金球藻.实验结果显示:循环阈值和抑食金球藻细胞丰度之间存在良好线性关系(R²= 0.91).应用实时定量PCR技术对采自秦皇岛近岸海域的24份海水样品进行了检测分析,发现抑食金球藻在秦皇岛近岸海域广泛分布.根据抑食金球藻细胞丰度及褐潮分级标准,2013年8月份,东山海水浴场和老虎石海水浴场发生3级抑食金球藻褐潮;在贝类养殖区,4个站位发生3级褐潮,6个站位发生2级抑食金球藻褐潮.而在2013年10月份,贝类养殖区所有站位均发生1级抑食金球藻褐潮.实时定量PCR技术可以检测到海水样品中的微量抑食金球藻,这对褐潮灾害的提前预警及灾害管理至关重要.

The seasonal thermal structure in the Bohai Sea are examined with a three-dimensional boroclinic primitive equation model for shelf sea.The evolution of the seasonal thermal stratification is well simulated.The stratification appears early in April, first in the area off Qinhuangdao and it is well developed in the middle of May.It intensifies with synoptic and neap-spring fluctuations throughout the summer and reaches its maximum in the middle of July.Eventually, it is destroyed at the end of September.There are cold water belts between well-mixed and stratified regions.They are loGated on the mixed side of tidal fronts, and coincide with the isolines for a temperature difference of 1-2℃ between surface and bottom.The sea surface temperature (SST) distribution shows local maxima at the head of three bays and to the south of Qinhuangdao during the summer.The Bohai Sea responds to the variability in the atmospheric forcing and in tides with the synoptic and neap-spring variations of SST, as well as in the stratification and in variable positions of tidal fronts.

Appropriate pathogenic bacteria were isolated from diseased (or dead) flounder (Paralichthys olivaceus L) occurring in a mariculture farms of Qinhuangdao, which all diseased fishes expressed bacterial septieaemia. The phenotypic information of the 12 pure cultures was studied extensively, including morphological characteristics, colony characteristics in different media, physiological and biochemical characteristics, and the mole fraction G+C ratio of the DNA for representative strain. The results show that the isolates belong to a new species of Vibrio, and are designated as Vibrio qinhuangdaora sp.nov. by the area from which the diseased flounders are collected (Qinhuangdao) based on its biological properties following Rules of International Code of Nomenclature of Bacteria. At the same time,studies on the serum homology of isolates, and pathogenicity of isolates were conducted by experimental infection. The results show that all the isolates are of serologic similarity, and the isolates have strong pathogenicity to flounder. The studies can extensively reflect the main biological properties of this new species of Vibrio.

Green tidal algal Enteromorpha species complete their life cycles by the isomorphic alternation of generations. The provenance of green tide caused by them in the western Yellow Sea has been disputed. The cell reproduction derived from adult thallus was observed on E. clathrata collected from Shantou City, Guangdong Province in this study. Subsequently, it further found that E. proliferia collected from Qingdao City, Shandong Province and Qinhuangdao City, Hebei Province, produced reproductive cells by somatic cells of its early infantile thallus or branch. The latter is functionally similar to that the seedlings of red alga Porphyra yezoensis produce the monospores, and could exquisitely explain the ephemeral or opportunistic trait and environmental adaptation ability of Enteromorpha species. Changes in growth conditions may induce the two types of cell reproduction. They contribute to the bloom, and can effectively reveal the seasonally occurring large-scale and on-year and off-year phenomenon. The latter may have played a decisive role in its formation. This paper analyses the legal status of the species name, the type of generation during bloom, ephemeral traits, the role of microscopic propagule, the area of origin, on-year and off-year phenomenon, early warning and prevention and control of the species, and so on. On this basis, further study on the influence of environmental factors on cell reproduction of early infantile thalli or branches will achieve a positive effect for early warning and prevention and control of the green tidal algal bloom.