SEA OTTER PREDATION AND COMMUNITY ORGANIZATION IN WESTERN ALEUTIAN ISLANDS, ALASKA
SEA OTTER PREDATION AND COMMUNITY ORGANIZATION IN WESTERN ALEUTIAN ISLANDS, ALASKA
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DOI：
10.2307/1938786
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发表时间：
1978-01-01
期刊：
影响因子：
4.8
通讯作者：
PALMISANO, JF
中科院分区：
文献类型：
--
作者：
ESTES, JA;SMITH, NS;PALMISANO, JF
海獭（Enhydra lutris）的捕食限制了底栖无脊椎动物，特别是海胆（strongylocentrrotus polyacanthus），反过来又允许大藻冠层的繁荣发展。在海獭数量较多的浅水区，海胆数量少、数量少，肉质巨藻的结合明显受竞争调节。海胆在较深的水域更大、更丰富，海獭很难接近。大型藻类最丰富，在植物群落中竞争最激烈，靠近沿海边缘，海獭可以最有效地清除海胆。在较深的水域，由于光照强度较低，海胆的放牧增加，大型藻类之间的竞争减少。在没有海獭的岛屿上，海胆数量丰富，体型庞大，可能受到种内竞争的限制；他们已经消灭了肉质的大型藻类。[j]。在阿留申群岛西部近岸地区，格伦兰属（groenlandica）、牙齿草属（L. dentigera）、叶藻属（L. yezoensis）和长叶草属（L. longipes）和沙生蘑菇（Agarum cribrosum）对初级生产贡献最大。在没有海獭和海胆消除了这种植物联系的地方，一些更高营养形式也没有出现，或者比海獭常见和植物联系发达的地方更少。早期对海獭食物的研究表明，在西阿留申群岛（美国），低密度的海獭主要食用海胆和软体动物。后来对高密度人群的研究表明，他们食用的食物种类更丰富，鱼类是饮食的重要组成部分。讨论了在有海獭和没有海獭的岛屿之间这些食物的可得性的差异。
Predation by the sea otter (Enhydra lutris) limits epibenthic invertebrates, especially sea urchins (Strongylocentrotus polyacanthus), in turn allowing a luxuriant development of the macroalgal canopy. Where sea otters are abundant, sea urchins are small and scarce in shallow water, and the association of fleshy macroalgae apparently is regulated by competition. Sea urchins are larger and more abundant in deeper water, where they are less accessible to sea otters. Macroalgae are most abundant and competition in the plant association is severest, near the sublittoral fringe where sea otters can remove sea urchins most efficiently. In deeper water, competition among macroalgae is reduced because the light intensity is lower and grazing by sea urchins increases. On islands where sea otters are absent, sea urchins are abundant, large and are probably limited by intraspecific competition; and they have eliminated fleshy macroalgae. The association of Laminaris spp. [L. groenlandica, L. dentigera, L. yezoensis and L. longipes] and Agarum cribrosum contributes most to primary production in nearshore areas of the western Aleutian Islands. Where sea otters are absent and sea urchins have eliminated this plant association, some higher trophic forms also are absent or less abundant than where sea otters are common and the plant association is well developed. Earlier studies of sea otter food suggested that low-density populations of sea otters consume primarily sea urchins and mollusks in the western Aleutian Islands [USA]. Later studies of high-density populations showed a wider variety of foods consumed, with fish an important component of the diet. The differences in availability of these foods between islands with and without sea otters are discussed.