FOOD AVAILABILITY, SEA-URCHIN GRAZING, AND KELP FOREST COMMUNITY STRUCTURE
FOOD AVAILABILITY, SEA-URCHIN GRAZING, AND KELP FOREST COMMUNITY STRUCTURE
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DOI：
10.2307/1939168
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发表时间：
1985-01-01
期刊：
影响因子：
4.8
通讯作者：
REED, DC
中科院分区：
文献类型：
--
作者：
HARROLD, C;REED, DC
与大多数先前报道的在大空间尺度上表现出长期持久性的海带森林不同，加州[美国]圣尼古拉斯岛伦敦西区的海带森林群落是一个动态的斑块，其特征是以放牧海胆和由直立和结壳珊瑚藻组成的藻类组合为特征的贫瘠地区，以及以高密度的多年生褐藻为特征的海带为主的地区。包括巨型海藻巨囊藻研究了海胆摄食活动的调节因子。francisanus），这反过来又决定了这个社区的结构进行审查。在贫瘠的地区，漂流藻类稀少，海胆营养不良，占据开放，未受保护的微栖息地，并积极放牧的底层。在海带占主导地位的地区，漂流藻类丰富，海胆营养良好，很少移动，占据裂缝和裂缝，并可能以漂流藻类为食。在研究初期，两个地点都发生了大量的棕色大型藻类的招聘，贫瘠的地区逐渐转变为海带为主的地区。与此同时，荒漠区漂流藻的丰度也随之增加。海胆在这一领域放弃了开放的微生境的保护裂缝和口袋，海胆放牧强度降低到海带为主的地区的特点。从这些观察的定性模型中，从一个配置到另一个的转换是由行为开关的模式喂养的红海胆触发。这种转换是由漂流藻类的可用性控制的，而漂流藻类的可用性又取决于附着的大型藻类的丰度。成年藻类常备股票似乎是受当时的水文条件，这是有利或不利的海带招聘，生存和增长。在这个模型中，放牧强度是独立的海胆密度，因此提供了一个新的观点如何海带森林群落功能。
Unlike most previously reported kelp forests, which exhibit long-term persistence over large spatial scales, the kelp forest community on the west end of San Nicolas Island, California [USA] occurs as a dynamic patchwork of barren areas characterized by grazing sea urchins and an algal assemblage consisting of upright and encrusting coralline algae, and kelp-dominated areas characterized by high densities of perennial brown algae, including the giant kelp Macrocystis pyrifera. The factors that regulate the grazing activity of sea urchins (S. francisanus), which in turn determines the structure of this community are examined. In the barren area, drift algae were sparse, sea urchins were poorly nourished, occupied open, unprotected microhabitats, and actively grazed the substratum. In the kelp-dominated area, drift algae were abundant, sea urchins were well nourished, moved little, occupied cracks and crevices, and probably fed on drift algae. Early in the study substantial recruitment of brown macroalgae occurred in both sites, and the barren area gradually transformed into a kelp-dominated area. Concomitant with this change, the abundance of drift algae in the barren area increased. Urchins in this area abandoned open microhabitats for protected crevices and pockets; sea urchin grazing intensity was reduced to levels characteristic of the kelp-dominated area. From these observations a qualitative model is presented in which the transformation from one configuration to another is triggered by a behavioral switch in the mode of feeding of red sea urchins. This switch is controlled by the availability of drift algae, which in turn is dependent upon the abundance of attached macroalgae. The adult algal standing stocks appear to be regulated by prevailing hydrographic conditions, which are either favorable or unfavorable for kelp recruitment, survivorship, and growth. In this model grazing intensity is independent of urchin density and therefore provides a new view of how kelp forest communities function.