还原态氮源在微小原甲藻大规模赤潮中的重要性--动力学模型

1998年春末夏初，在美国的切萨皮克海湾的Choptank河出现了由微小原甲藻引发的大规模的赤潮。我们做了一系列与该藻赤潮发生机制有关的生理学特征实验。其中与氮吸收有关的生理学参数被应用于微小原甲藻赤潮发生动力学模型。为说明几个关键的生态及生理学过程在微小原甲藻赤潮发展和持续过程重的重要性，我们用该模型测试了几个关键过程点。模型测试的结果表明，河流输入充足的氮源是引起微小原甲藻赤潮的关键因素，而输入营养盐的组成结构对赤潮的发生并不起主要作用。然而在赤潮形成后，赤潮的维系依赖于还原态的氮源。在赤潮的维持过程中，微小原甲藻的倾向于吸收还原态的氮源的生理学特征起了很大作用。模型进一步表明微小原甲藻在低光照或黑暗条件下对氮的吸收仍然保持相当的吸收速率有利于该藻赤潮的发展。

The importance of reduced nitrogen in a natural Prorocentrum minimum bloom - a model approach

In the late spring and early summer of 1998, an extensive Prorocentrum minimum bloom developed in the Choptank River of Chesapeake Bay, USA. A series experiments were conducted to determine the physiological characteristics of P. minimum in relation to its bloom development. These physiological characteristics in term of nitrogen uptake were applied toward the development of a simulation model of P. minimum bloom dynamics. Several scenarios were tested with this model to demonstrate the importance of some key ecological and physiological processes in the development and maintenance of P. minimum blooms. Model results suggested an initial pulse of sufficient nitrogen from river flow was essential for the bloom initiation, but the composition of this initial nutrient delivery was not significant in bloom initiation. However, the bloom was sustained by reduced nitrogen sources after its establishment. The physiological preference for reduced nitrogen uptake by P. minimum therefore plays an importance role in bloom maintenance, with reduced nitrogen representing more than 90% of total nitrogen uptake in the bloom peak period. The model further suggested that the ability of P. minimum to maintain a significant uptake of nitrogen under low light or dark conditions would be advantageous in its bloom development.