Burkepile Deron E, Hay Mark E
Georgia Institute of Technology, School of Biology, 310 Ferst Drive, Atlanta, GA 30332, USA.
Oecologia. 2007 Nov;154(1):167-73. doi: 10.1007/s00442-007-0801-4. Epub 2007 Jul 17.
When large, predatory fishes and invertebrates were excluded from areas of a coral reef in the Florida Keys, USA, densities of the normally rare gastropod Cyphoma gibbosum, a principal predator of gorgonian corals, increased 19-fold. Gorgonians in predator exclosures were grazed more frequently and extensively by C. gibbosum than were gorgonians in uncaged areas. In exclosures, 14% of all gorgonians showed recent predation by C. gibbosum, with 62% of the entire colony surface being removed from these attacked individuals. In areas where predators of C. gibbosum were not excluded, only 5% of gorgonians exhibited recent damage, with only 26% of the colony surface being removed from these few damaged individuals. Thus, the increases in both frequency and extent of attack combined to produce an 8x increase in gorgonian damage following removal of large predators. These patterns suggest that predators typically suppress C. gibbosum populations, that overfishing of these predators could release C. gibbosum from top-down control, and that this release will allow increased damage to gorgonian corals.
在美国佛罗里达群岛，当大型掠食性鱼类和无脊椎动物被排除在珊瑚礁区域之外时，通常较为稀少的腹足纲动物突角海牛（Cyphoma gibbosum）（柳珊瑚的主要捕食者）的密度增加了19倍。与未设围栏区域的柳珊瑚相比，在捕食者排除区的柳珊瑚遭受突角海牛啃食的频率更高、范围更广。在排除区内，所有柳珊瑚中有14%近期遭受过突角海牛的捕食，这些被攻击个体的整个群体表面有62%被啃食掉。在未排除突角海牛捕食者的区域，只有5%的柳珊瑚近期受到损伤，而且在这少数受损个体中，群体表面只有26%被啃食掉。因此，攻击频率和范围的增加共同导致在大型捕食者被移除后，柳珊瑚的损伤增加了8倍。这些模式表明，捕食者通常会抑制突角海牛的数量，过度捕捞这些捕食者可能会使突角海牛摆脱自上而下的控制，而这种释放将导致柳珊瑚受到更大的损伤。
