Inorganic nitrogen metabolism by Antarctic phytoplankton with special reference to ammonium cycling
Inorganic nitrogen metabolism by Antarctic phytoplankton with special reference to ammonium cycling
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南极浮游植物的无机氮代谢，特别是铵循环
DOI：
10.3354/meps030105
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发表时间：
1986
影响因子：
2.5
通讯作者：
D. Biggs
中科院分区：
文献类型：
--
作者：
I. Koike;O. Holm‐Hansen;D. Biggs
1981年2月至3月，在M e l d l e号考察船上对斯科舍海南部沿岸沃茨中浮游生物的氮代谢进行了研究。尽管这些沃茨（21至29 FM）中存在高浓度的硝酸盐，但高达93%的浮游植物氮以铵的形式被同化，总体平均值为78%。时间过程的实验表明，在夜间的硝酸盐和铵的吸收约为15%和50%，分别为白天的值。硝酸盐和铵在较小程度上的这种光依赖性反映在硝酸盐和铵同化的深度剖面中。在象岛附近的斯科舍弧的浅沃茨，大部分的铵吸收与微型浮游生物（< 20 μ m的大小）的吸收。从细菌、浮游植物和浮游动物的生物量和代谢活动估算通过食物网的铵通量表明，异养微生物是负责大部分由浮游植物再生和同化的铵。同位素稀释实验的数据证实，微型食草动物占大部分的再生铵。讨论了这些沿海沃茨中铵的高浓度（平均为2.1 FM）与季节性事件和浮游动物活动的关系。
Nitrogen metabolism of planktonic populations in coastal waters of the southern Scotia Sea was studied in February-March 1981 aboard R/V M e l d l e . In spite of the high concentration of nitrate present in these waters (21 to 29 FM), up to 93 % of phytoplankton nitrogen was assimilated in the form of ammonium, with the overall mean being 78 %. Time course experiments showed that uptake of nitrate and ammonium during nighttime amounted to approximately 15 and 50 %, respectively, of daytime values. This light dependency of nitrate, and to a lesser extent ammonium, is reflected in the depth profiles of nitrate and ammonium assimilation. Over the shallow waters of the Scotia Arc close to Elephant Island, most of the ammonium uptake was assoc~ated wlth nanoplankton (< 20 ,pm size). Estimating the flux of ammonium through the food web from the biomass and metabolic activities of bacteria, phytoplankton and zooplankton suggests that heterotrophic microbial organisms are responsible for most of the ammonium which is regenerated and assirmlated by phytoplankton. Data from isotope dilution experiments confirmed that micrograzers do account for most of the regenerated ammonium. The high concentrahons of ammonium in these coastal waters (average of 2.1 FM) are discussed relative to seasonal events and to zooplankton activity.