Ammonium cycling by Antarctic zooplankton in winter
Ammonium cycling by Antarctic zooplankton in winter
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冬季南极浮游动物的铵循环
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
W. Nordhausen
中科院分区：
文献类型：
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作者：
M. Huntley;W. Nordhausen
在南极半岛以西的沿海沃茨，于仲冬季节测定了体型大小在5个数量级以上的浮游动物的元素组成和氨氮排泄率。排泄率是恒定的初始12小时的孵育在四个物种的测试，和实验放养密度高达126毫克干重l-1没有引起变异的铵生产率。新鲜捕获的南极真刺水蚤、Conchoecia sp.、大型Thysanoessa macrura、南极磷虾Euphausia superba和Gerlachei的早期桡足类与夏季报道的无显著差异。然而，成年桡足类的M。gerlachei和Calanoides acutus似乎在冬季降低了它们的氮代谢。体氮周转率随体积减小而增加，<0.5% body N d-1 for large E. superba to >CII和CIII桡足类的体氮周转率为7%。杰拉切。只有C. acutus的温度很低，这表明它可以在没有进食的情况下度过整个南方冬季。在水柱和海冰中，浮游植物和浮游细菌几乎都不存在。我们的结论是，肉食性的浮游动物群落在南极冬季占主导地位的营养模式。浮游动物群落产生的铵态氮可能占每年春季水华前总铵再生量的M10%。
Elemental composition and excretion rates of ammonium-nitrogen of zooplankton, ranging over more than five orders of magnitude in body size, were measured in mid-winter in coastal waters west of the Antarctic Peninsula. Excretion rates were constant for the initial 12 h of incubation in the four species tested, and experimental stocking densities of up to 126 mg dry wt l-1 did not cause variability in the rate of ammonium production. Weight-specific excretion rates of freshly caught Euchaeta antarctica, Conchoecia sp., Thysanoessa macrura, Euphausia superba, and early stage copepodites of Metridia gerlachei were not significantly different from those reported in summer. However, adult copepods of M. gerlachei and Calanoides acutus appear to have reduced their nitrogen metabolism during winter. Turnover rates of body nitrogen increased with diminishing size, ranging from <0.5% body N d-1 for large E. superba to >7% body N d-1 for CII and CIII copepodites of M. gerlachei. Only the nitrogen turnover rates of C. acutus were sufficiently low as to suggest that it could survive the entire austral winter without feeding. Phytoplankton and bacterioplankton were virtually absent in both the water column and the sea-ice. We conclude that carnivory is the dominant trophic mode of the pelagic zooplankton community in Antarctica during winter. Production of ammonium-nitrogen by the zooplankton community probably accounts for M10% of the total ammonium regenerated prior to the annual spring bloom.