Role of silicon as a limiting nutrient to Antarctic diatoms: evidence from kinetic studies in the Ross Sea ice-edge zone
Role of silicon as a limiting nutrient to Antarctic diatoms: evidence from kinetic studies in the Ross Sea ice-edge zone
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DOI：
10.3354/meps080255
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发表时间：
1992
影响因子：
2.5
通讯作者：
D. M. Nelson;P. Tréguer
中科院分区：
文献类型：
--
作者：
D. M. Nelson;P. Tréguer
在1990年南半球夏季，罗斯海西南部的冰缘浮游植物大量繁殖，导致南极洲表层沃茨中硝酸盐和磷酸盐的浓度大大低于典型浓度。在融水场的核心内，硅酸被耗尽至<6 μ m，其中生物颗粒二氧化硅浓度超过20 μ m。对来自营养物耗尽区的天然浮游植物组合进行三次Si吸收动力学实验;使用30 Si标记的Si（OH）测量在高于环境1至20 μ m的浓度范围内的吸收速率。比吸收速率（V）与草酸浓度的关系符合Michaelis-Menten饱和模型，最大吸收速率（V，）范围为0.0022 ~ 0.0028 h-1，对应最大生长速率为0.08 ~ 0.10倍/d-1。半饱和常数（km）的范围从1.1到4.6 PM，一个范围类似于在海洋的其他地区发现的值，大大低于以前报道的几个南极d~原子物种的文化研究。结果表明，在罗斯海西部的自然发生的硅藻组合的S~llcic酸吸收率检测，但弱，基板限制。在南大洋的其他子系统中的显着的硅限制将是可能的，只有当他们的居民硅藻组合有比我们观察到的低得多的亲合力的柠檬酸。
During the austral summer of 1990 an intense, diatom-dominated, ice-edge phytoplankton bloom in the southwestern Ross Sea resulted in depletion of silicic acid, nitrate and phosphate to concentrations much lower than is typical for Antarctic surface waters. Silicic acid was depleted to <6 FM within the core of the meltwater field, where biogenic particulate silica concentrations exceeded 20 pm01 1-' Three Si uptake kinetic experiments were conducted on natural phytoplankton assemblages from the nutrient-depleted zone; 30Si-labeled Si(OH), was used to measure the uptake rate at concentrations ranging from 1 to 20 PM above ambient. Dependence of the spec~fic uptake rate ( V ) on silicic acid concentration conformed well to a Michaelis-Menten saturation model; maximum uptake rates (V,,,,,) ranged from 0.0022 to 0.0028 h' which corresponds to maximum growth rates of 0.08 to 0.10 doublings d-l. Half-saturation constants (km) ranged from 1.1 to 4.6 PM, a range similar to values found in other areas of the ocean and considerably lower than those previously reported for several Antarctic d~atom species in culture studies. Results indicate detectable, but weak, substrate limitation of s~llcic acid uptake rate by the naturally occurring diatom assemblage in the western Ross Sea. Significant Si limitation in other subsystems of the Southern Ocean would be possible only if their resident diatom assemblages had much lower affinity for silicic acid than we observed.