TEMPORAL AND SPATIAL SCALES OF KELP DEMOGRAPHY: THE ROLE OF OCEANOGRAPHIC CLIMATE
TEMPORAL AND SPATIAL SCALES OF KELP DEMOGRAPHY: THE ROLE OF OCEANOGRAPHIC CLIMATE
复制标题
海藻种群的时空尺度：海洋气候的作用
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Kristin L. Riser
中科院分区：
文献类型：
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作者：
P. Dayton;M. Tegner;P. B. Edwards;Kristin L. Riser
本文整合了海洋气候对种间和种内竞争影响的长期描述性和实验研究，具体表现为美国加利福尼亚州圣地亚哥附近洛马角海带森林群落中最显着的海带物种的补充、密度、生存、生长和繁殖。该物种包括Macrocystis Pyrifera，具有漂浮的树冠； Pterygophora californica 和 Eisenia arborea，它们依靠叶柄来支撑其树冠；海带，具有匍匐的树冠；和一片特殊的红藻草皮。为了评估大规模海洋学过程对跨重要深度梯度的生物过程的作用，该研究在冷水、营养丰富的拉尼娜事件（1988-1989）和温水、营养紧张的厄尔尼诺时期（1992-1994）期间进行了九年，深度范围为8-23 m。该深度范围包含强烈的物理梯度，涉及对海带生长至关重要的因素，包括底部温度（与营养物质相关）和光照水平。为了检查这些海带之间的相互作用，我们在深度梯度上建立了空地，然后操纵巨藻的招募密度。人口统计反应提供了对这些物种的“基本”与“实现”利基的理解。评估这些模式，因为它们受到种间和种内竞争的影响，可以深入了解海带的“已实现的生态位”。除了林下对大囊藻补充的一些影响以及营养丰富的拉尼娜条件下种内竞争的一些证据外，我们发现竞争效应对大囊藻的影响很小。翼藻对操纵和干扰的反应表明其招募受到限制，并且通过减少生长和繁殖来表现出与大囊藻的竞争，但不是存活率。在翼龙繁殖中没有观察到营养胁迫。爱胜蚓的招募很少见，但一旦建立，幼体就有很好的生存能力，生长和繁殖随着深度的增加而减少；大囊藻的处理比深度更重要，这表明光对爱胜蚓的补充和生长的重要性。总的来说，大囊藻对海带的生长和繁殖具有巨大的影响，其强度随深度而变化。特别是在营养丰富的拉尼娜时期，当大囊藻具有致密的表层冠层时，与大囊藻的竞争效应非常强烈。除了大囊藻的影响外，厄尔尼诺期间，翼藻对海带的生长也产生了一些显着的影响。对已实现生态位的最强烈的生物学定义发生在营养丰富的拉尼娜时期，特别是在浅层深处。本文最重要的结论之一是认识到及时缩放以纳入海洋气候的重要性。有许多季节模式，但包括厄尔尼诺和拉尼娜的年际尺度，以及最终影响冠层与大囊藻竞争强度的年代际尺度海洋状况变化，对于该系统至关重要，因为地表水营养物对其他海带具有普遍的长期影响。小规模模式是由局部过程（竞争、干扰、分散等）驱动的，这些过程在更大范围内可能很重要；然而，我们最持久的影响来自于营养物质的大规模、低频偶发性变化，并对群落中的其他藻类种群产生级联竞争后果。
This paper integrates long-term descriptive and experimental studies of the effects of ocean climate on inter- and intraspecific competition, as expressed by recruitment, density, survivorship, growth, and reproduction of the most conspicuous kelp species in the Point Loma kelp forest community off San Diego, California, USA. The species included Macrocystis pyrifera,with a floating canopy; Pterygophora californicaand Eisenia arborea, which rely on stipes to support their canopy; Laminaria farlowii, with a prostrate canopy; and a speciose red algal turf. To evaluate the roles of large-scale oceanographic processes on biological processes across important depth gradients, the study was carried out over nine years during a cold-water, nutrient-rich La Nina event (1988-1989) and a warm-water, nutrient-stressed El Nino period (1992-1994), over a depth range of 8-23 m. This depth range encompassed strong physical gradients involving factors that are critical for kelp growth, including bottom temperatures (correlated with nutrients) and light levels. To examine interactions among these kelps, we established clearings across the depth gradient and then manipulated Macrocystis recruit densities. The demographic responses offer an understanding of the 'fundamental' vs. 'realized' niches of these species. Eval- uating these patterns, as they are influenced by inter- and intraspecific competition, offers insights into the 'realized niches' of the kelps. With the exception of some understory effects on Macrocystis recruitment and some evidence of intraspecific competition during the nutrient-rich La Nina conditions, we found little influence of competitive effects on Macrocystis. The response of Pterygophora to manipulations and disturbances suggests light-limited recruitment, and competition with Macrocystis was exhibited via reduced growth and reproduction, but not survivorship. No nutrient stress was observed in Ptery- gophora reproduction. Eisenia recruitment is rare, but once established, juveniles had very good survivorship, with growth and reproduction reduced by depth; the Macrocystis treat- ment was more important than depth, suggesting the importance of light to Eisenia re- cruitment and growth. In general, Macrocystis had massive effects on Laminaria growth and reproduction, the strength varying with depth. In particular, there were very strong effects of competition with Macrocystis during the nutrient-rich La Nina period when Macrocystis had a dense surface canopy. In addition to the Macrocystis effects, there were some significant Pterygophora effects on Laminaria growth during El Nino. The strongest biological definition of realized niches occurred during the nutrient-rich La Nina period, especially in shallow depths. One of the most important conclusions of this paper is the appreciation of the importance of scaling in time to include oceanographic climate. There are many seasonal patterns, but the interannual scales that encompass El Ninos and La Ninas, and ultimately the interdecadal-scale oceanographic regime shifts that affect the intensity of canopy competition with Macrocystis, are critical for this system because surface-water nutrients have pervasive long-term effects on the other kelps. Small- scale patterns are driven by local processes (competition, disturbance, dispersal, etc.) that potentially are important at larger scales; however, our most lasting effects result from very large-scale, low-frequency episodic changes in nutrients, with cascading competitive con- sequences to the other algal populations in the community.