Ecological features of harmful algal blooms in coastal upwelling ecosystems
Ecological features of harmful algal blooms in coastal upwelling ecosystems
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DOI：
10.2989/025776100784125816
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发表时间：
2000-06
期刊：
影响因子：
--
通讯作者：
T. Smayda
中科院分区：
文献类型：
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作者：
T. Smayda
上升流区是甲藻产生赤潮最复杂的生境，但其植物群并不是唯一的。许多物种也在营养丰富的非上升流系统中开花，共享低营养亲和力的集体甲藻特征，并且可以实现相对较快的生长速率。水华发生在上升流栖息地中发现的营养混合平流组合的范围内，而不是局限于Margalef的经典曼陀罗及其Bowman等人和Pingree版本所假设的高营养高辐照低湍流条件。水华物种主要是ruderal战略家（R-种），这是典型的“混合漂移”的生命形式，适应与锋区，夹带在沿岸流的速度，并在上升流松弛的垂直混合。总的来说，腰鞭毛虫似乎能够生存相当高的湍流谱形成的代表性柯尔莫哥洛夫长度尺度风速条件。这种生物物理保护可能是湍流能量耗散过程中形成的微涡内细胞大小促进夹带的结果。71个克隆的甲藻的游泳速度进行了比较，并与沿海上升流系统中的垂直运动速率的报告。有慢和快的游泳者，许多表现出运动率，可以超过代表性的原位垂直和水平的水体运动。至少有四个腰鞭毛虫从上升流系统形成链，导致游泳速度增加，并可能是一种适应沿海上升流栖息地的增长。赤潮是上升流系统的常见和基本特征，特别是在间歇性上升流松弛期间，而不是由上升流引起的硅藻水华的二分（有时是灾难性的）中断。上升流系统和非上升流系统的演替序列和赤潮带可能不同。在后者中，赤潮偏离主序列，并适当地定位在曼荼罗的高营养和低湍流的生态空间。基于Pingree的S-kh模型和Smayda和Reynolds生命形式模型提出了一个修正的Mandala，以适应在沿海上升流系统中发现的赤潮发展及其演替路由的范围。生理生态数据支持Pitcher和Boyd播种机制模型，该模型可导致上升流系统中的赤潮。研究了营养盐、植物刺激和放牧压力对上升流系统赤潮的触发作用。有些红潮可能是由洄游的鱼群和浮游动物群的“脓疮”所分泌的营养物和促生长因子所刺激，而浮游动物的选择性摄食亦是原因之一。放牧压力的大幅度崩溃可能是缺氧赤潮事件的关键。本格拉和秘鲁上升流系统共同的缺氧导致的大量死亡可能是一种营养控制机制，以维持上升流生态系统动力学中至关重要的生态地球化学平衡和区域动态平衡。一些传统的浮游植物生态学概念可能不完全适用于沿岸上升流系统中的甲藻水华事件。
Upwelling regions are the most complex habitats in which dinoflagellates produce red tides, but the flora is not unique. Many species also bloom in nutrient-enriched, non-upwelling systems, share the collective dinoflagellate trait of low-nutrient affinity, and can achieve relatively fast growth rates. Blooms occur over the range of nutrient – mixing – advection combinations found in upwelling habitats, rather than being restricted to the high-nutrient high-irradiance low-turbulence conditions posited by Margalef's classical Mandala and its Bowman et al. and Pingree versions. The bloom species are primarily ruderal strategists (R-species), which typify "mixing – drift" life-forms adapted to the velocities associated with frontal zones, entrainment within coastal currents, and vertical mixing during upwelling relaxations. Collectively, dinoflagellates appear capable of surviving fairly high turbulence spectra formed at representative Kolmogorov length scale – wind speed conditions. This biophysical protection might be the result of cell size-facilitated entrainment within the micro-eddies formed during turbulent energy dissipation. The swimming speeds of 71 clones of dinoflagellates are compared and related to reported rates of vertical motion in coastal upwelling systems. There are slow and fast swimmers; many exhibit motility rates that can exceed representative in situ vertical and horizontal water mass movements. At least four dinoflagellates from upwelling systems form chains leading to increased swimming speeds, and may be an adaptation for growth in coastal upwelling habitats. Red tides are frequent and fundamental features of upwelling systems, particularly during intermittent upwelling relaxations, rather than dichotomous (sometimes catastrophic) interruptions of the diatom blooms characteristically induced by upwelling. Successional sequences and the "red tide" zone may differ between upwelling and non-upwelling systems. In the latter, red tides diverge from the main sequence and are appropriately positioned in the Mandala's ecological space of high nutrients and low turbulence. An amended Mandala based on Pingree's S-kh model and the Smayda and Reynolds life-form model is presented to accommodate the range of red tide development and their successional routing found in coastal upwelling systems. Ecophysiological data support the Pitcher and Boyd seeding mechanism model, which can lead to red tides in upwelling systems. Nutrients, phyto-stimulation and grazing pressure as triggering factors in upwelling-system red tides are considered. Some red tides may be stimulated by nutrients and growth promoting factors excreted by migrating shoals and "boils" of c1upeoid stocks, with selective zooplankton grazing contributory. Substantial collapses in grazing pressure may be essential in anoxic red tide events. The mass mortalities that accompany anoxia, common to the Benguela and Peru upwelling systems, may be a trophic control mechanism to maintain biogeochemical balance and regional homeostasis, which are vital to upwelling ecosystem dynamics. Some traditional concepts of phytoplankton ecology may not completely apply to dinoflagellate bloom events in coastal upwelling systems.