Small-scale spatial structure in plankton distributions
Small-scale spatial structure in plankton distributions
复制标题
浮游生物分布的小尺度空间结构
DOI：
10.5194/bg-4-173-2007
复制
发表时间：
2006
期刊：
影响因子：
4.9
通讯作者：
P. Haynes
中科院分区：
文献类型：
--
作者：
A. Tzella;P. Haynes
摘要。浮游生物种群的丝状特性表明，搅拌在决定其空间结构方面起着重要作用。如果忽略扩散混合，则流体包内各种相互作用的生物物种由包时间历史决定。诱导的空间结构已被证明是所涉及的生物过程的时间演变与由流动引起的搅拌之间竞争的结果，例如，通过邻近流体包的距离发散率来测量。在这里介绍的工作中，我们研究了一个简单的基于延迟微分方程的生物模型，该模型以前在Abraham（1998）中看到过，包括营养物质、浮游植物和浮游动物，以及应变流。先前对微分方程模型的理论研究（Hernandez-Garcia et al., 2002）表明，后两者应该具有相同的小尺度结构。如果考虑到足够小的空间尺度，从微分方程到延迟微分方程的推广与浮游动物生长成熟时间的增加有关，应该不会产生差异。然而，这一理论预测与Abraham（1998）的结果相矛盾，后者认为浮游植物和浮游动物的结构在所有长度尺度上都不相关。本文进行了一组新的数值实验，证明了这两种状态是共存的。在更大尺度上，浮游动物分布的空间结构与浮游植物与营养物分布的空间结构存在解耦关系。另一方面，在足够小的长度尺度上，浮游植物和浮游动物共享相同的空间结构，正如理论所期望的那样，不涉及成熟时间。
Abstract. The observed filamental nature of plankton populations suggests that stirring plays an important role in determining their spatial structure. If diffusive mixing is neglected, the various interacting biological species within a fluid parcel are determined by the parcel time history. The induced spatial structure has been shown to be a result of competition between the time evolution of the biological processes involved and the stirring induced by the flow as measured, for example, by the rate of divergence of the distance of neighbouring fluid parcels. In the work presented here we examine a simple biological model based on delay-differential equations, previously seen in Abraham (1998), including nutrients, phytoplankton and zooplankton, coupled to a strain flow. Previous theoretical investigations made on a differential equation model (Hernandez-Garcia et al., 2002) imply that the latter two should share the same small-scale structure. The generalisation from differential equations to delay-differential equations, associated with the addition of a maturation time to the zooplankton growth, should not make a difference, provided sufficiently small spatial scales are considered. However, this theoretical prediction is in contradiction with the results of Abraham (1998), where the phytoplankton and zooplankton structures remain uncorrelated at all length scales. A new set of numerical experiments is performed here which show that these two regimes coexist. On larger scales, there is a decoupling of the spatial structure of the zooplankton distribution on the one hand, and the phytoplankton and nutrient on the other. On the other hand, at small enough length scales, the phytoplankton and zooplankton share the same spatial structure as expected by the theory involving no maturation time.