Destructive grazing by sea urchins Strongylocentrotus spp. in a central California kelp forest: potential roles of recruitment, depth, and predation
Destructive grazing by sea urchins Strongylocentrotus spp. in a central California kelp forest: potential roles of recruitment, depth, and predation
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海胆 Strongylocentrotus spp 的破坏性放牧。
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
C. Harrold
中科院分区：
文献类型：
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作者：
J. Watanabe;C. Harrold
1986 年 1 月，加利福尼亚州骆驼湾开始发生海胆介导的森林砍伐活动。美国，靠近加州海獭分布范围的中心。森林砍伐发生在近海岩礁上，深度范围为 l ?至 > 30 m。紫海胆 (Strongylocentrotus purpuratus) 和红海胆 (S. franciscanus) 数量都很丰富，可能属于 1984 年定居的群体。到 1986 年 10 月，几乎所有非壳藻类都已被清除，大多数固着无脊椎动物（不包括刺胞动物 Balanophyllia elegans 和 Corynactis californica）。从附近两个类似深度的森林地点同时采集的样本显示，没有证据表明海胆过度放牧。森林砍伐地点的红海胆数量保持相当稳定，但到 1989 年 7 月，紫海胆数量下降到零。森林砍伐期间出现了藻类孢子，但直到海胆丰度下降后才出现海藻的补充。虽然不太可能被海獭捕食，但紫海胆数量下降的原因尚不清楚。围绕这些事件的情况表明，海带森林砍伐不仅可以通过成年海胆的死亡率（因捕食或疾病）和其食物供应的波动来控制，还可以通过影响补充的因素（如幼体丰度和早期定居后的日光竞争）来控制。
In January 1986, a sea-urchm mediated deforestation began in C a m e l Bay, California. USA, near the center of the California sea otter's range. The deforestation occurred on an offshore rocky reef where depths range from l ? to > 30 m. Both purple (Strongylocentrotus purpuratus) and red (S. franciscanus) sea urchins were abundant and probably belonged to a cohort that settled in 1984. By October 1986, nearly all non-crustose algae had been removed, as were most sessile invertebrates (excluding the cnidarians Balanophyllia elegans and Corynactis californica). Concurrent samples taken from 2 nearby forested sites at comparable depths showed no evidence of overgrazing by urchins. Populations of red sea urchins at the deforested site remained fairly stable, but purple sea urchins declined to zero by July 1989. Algal spores were available during the deforestation, but recruitment of seaweeds d d not occur until after sea urchln abundance had decllned Reasons for the decline of the purple sea urchin population are not clear, although predation by sea otters 1s unlikely. Circumstances surrounding these events indicate kelp forest deforestations may be controlled not only by mortality of adult sea urchins (from predation or disease) and fluctuation of their food supply, but also by factors affecting recruitment such a s larval abundance and early post-settlement sunrival.