The impact of mixotrophy on planktonic marine ecosystems
The impact of mixotrophy on planktonic marine ecosystems
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DOI：
10.1016/s0304-3800(99)00181-7
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发表时间：
2000-01-15
影响因子：
3.1
通讯作者：
Stoecker, DK
中科院分区：
文献类型：
--
作者：
Stickney, HL;Hood, RR;Stoecker, DK
混合营养原生生物利用光养和吞噬相结合的营养策略，常见于所有纬度的淡水、河口和海水中。许多不同生理类型的混合营养生物是可能的，包括能够同样良好地利用光养和吞噬营养的形式，主要是光养吞噬细胞“藻类”，以及主要是异养光合“原生动物”。混合营养生物预计会对生态系统的营养动态产生重要影响，但这些影响的确切性质尚不清楚，并且可能因生理类型而异。为了研究混合营养生物可能对微生物食物网产生的影响，我们开发了数学公式来模拟上述三种混合营养生物的生理类型。这些被引入理想化的、稳态的公海和沿海/河口环境。我们的结果表明，混合营养生物与浮游植物和浮游动物争夺资源，它们的相对丰度是摄食策略（生理类型以及它们是否以浮游动物为食）以及生物体的最大生长和/或放牧率的函数。在我们的模型中，混合营养生物与浮游植物和浮游动物的共存通常发生在合理的参数范围内，这表明混合营养生物代表了夏季准稳态条件下的独特资源利基。我们还发现，混合营养生物的引入往往会降低基于从溶解的无机氮库中吸收氮的初级生产，但是这种减少可以通过基于有机氮源的混合营养初级生产来补偿。 (C) 2000 Elsevier Science B.V. 保留所有权利。
Mixotrophic protists, which utilize a nutritional strategy that combines phototrophy and phagotrophy, are commonly found in fresh, estuarine, and oceanic waters at all latitudes. A number of different physiological types of mixotrophs are possible, including forms which are able to use both phototrophy and phagotrophy equally well, primarily phototrophic phagocytic 'algae', and predominantly heterotrophic photosynthetic 'protozoa'. Mixotrophs are expected to have important effects on the trophic dynamics of ecosystems, but the exact nature of these effects is not known and likely varies with physiological type. In order to study the impact that mixotrophs may have on the microbial food web, we developed mathematical formulations that simulate each of the three aforementioned physiological types of mixotrophs. These were introduced into idealized, steady-state open ocean and coastal/estuarine environments. Our results indicate that mixotrophs compete for resources with both phytoplankton and zooplankton and that their relative abundance is a function of the feeding strategy (physiological type and whether or not they feed on zooplankton) and the maximum growth and/or grazing rates of the organisms. In our models coexistence of mixotrophs with phytoplankton and zooplankton generally occurs within reasonable parameter ranges, which suggests that mixotrophy represents a unique resource niche under summertime, quasi-steady state conditions. We also find that the introduction of mixotrophs tends to decrease the primary production based on uptake of nitrogen from the dissolved inorganic nitrogen pool, but that this decrease may be compensated for by mixotrophic primary production based upon organic nitrogen sources. (C) 2000 Elsevier Science B.V. All rights reserved.