机构地区:[1]中国科学院海洋研究所海洋生态和环境科学重点实验室,山东青岛266071 [2]青岛海洋科学与技术国家实验室海洋生态与环境科学功能实验室,山东青岛266071 [3]中国科学院大学,北京100049
出 处:《海洋通报》2016年第3期241-251,共11页Marine Science Bulletin
基 金:中国科学院战略性先导科技专项(XDA11030202.2);973项目(2014CB441504)
摘 要:海洋浮游微食物网包括病毒、细菌、聚球藻蓝细菌、原绿球藻、微微型自养真核生物、微型浮游动物(混合营养和异养鞭毛虫、纤毛虫)等生物类群,其中病毒、细菌及微型浮游动物等异养生物类群是海洋中氮、磷营养盐再生的重要贡献者。海洋中细菌吸收还是释放营养盐取决于细菌与底物中元素的比例,在多数海区,异养细菌都是吸收营养盐。病毒主要通过溶解宿主来释放宿主细胞中的物质,释放的营养元素的存在形态大多为有机物。微型浮游动物对营养盐的再生主要通过排泄来完成,目前在实验室内测定微型浮游动物排泄率的研究比较少,进行研究的主要困难有两个:第一,微型浮游动物的室内培养较难;第二,测定微型浮游动物的代谢率技术难度较高。根据已有研究结果,鞭毛虫的单位体重排氮率为2.8~140μg N(mg DW)^(-1)h^(-1),最大排氮率为7.0×10-9~13.8×10-6μg NH4+N cell^(-1)h^(-1),再生效率为0~100%;最大排磷率为3.8×10-9~6.6×10-7μg P cell^(-1)h^(-1),再生效率为0~100%。鞭毛虫的营养盐排泄率和再生效率受鞭毛虫自身的生长阶段和生活策略、饵料中元素比例及温度的影响。纤毛虫的单位体重排氮率为0.25~178μg N(mg DW)^(-1)h^(-1),最大排氮率为1.59×10-7~1.2×10-4μg NH4+N cell^(-1)h^(-1);单位体重排磷率为13~363μg P(mg DW)^(-1)h^(-1),最大排磷率为0~1.3×10-5μg P cell^(-1)h^(-1)。影响纤毛虫排泄率和再生速率的主要因素为纤毛虫生长阶段和温度。自然海区测定微型浮游生物对营养盐的再生的方法主要为同位素稀释法,此外还可以根据其他资料推算微型浮游生物的营养盐再生速率及产生率以反映再生能力。多数野外实验结果证明微型浮游动物是营养盐主要的再生者。Marine planktonic microbial food web mainly includes viruses, bacteria, Synechococcus, Prochlorococcus,picoeukaryotes and microzooplankton( heterotrophic and pigmented nanoflagellates and ciliates). The heterotrophic taxonomic groups( including viruses, bacteria and microzooplankton) play an important role in nitrogen and phosphorus regeneration. In the sea, whether bacteria absorb or release nutrients depends on the element ratio of C : N or C : P in substrates. Most results indicate that heterotrophic bacteria absorb nutrients in the most area. Virus releases the nutrient elements mainly by dissolving the host cells. Excretion was the primary way for microzooplankton to regenerate the nutrients.However, only a few studies measuring the excretion rate of microzooplankton have been carried out in the laboratory due to the difficulties in(1) cultivation of marine microzooplankton in the lab, and(2) the determination of the microzooplankton metabolic rates. According to the previous research, the weight-specific nitrogen regeneration of nanoflagellates ranged from2.8 to 140 μg N(mg DW)^(-1)h^(-1). The maximum nitrogen excretion ranged from 7.0×10-9to 13.8×10-6μg NH4+N cell^(-1)h^(-1). The range of regeneration rates was 0~100 %. The maximum phosphorus excretion ranged from 3.8×10^(-9)to 6.6×10^(-7)μg P cell^(-1)h^(-1). The range of regeneration rates was 0~100 %. The excretion rate and regeneration rate were influenced by growth phase and living strategy of nanoflagellates, the ratio of the elements in the prey and temperature, etc. In the case of ciliates, the weight-specific nitrogen regeneration ranged from 0.25 to 178 μg N(mg DW)^(-1)h^(-1). The maximum nitrogen excretion ranged from1.59 ×10^(-7)to 1.2×10^(-4)μg NH4+N cell^(-1)h^(-1). The weight-specific phosphorus regeneration of ciliates ranged from 13 to 363 μg P(mg DW)^(-1)h^(-1). The maximum phosphorus excretion ranged from 0 to 1.3×10-5μg P ce
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