Hill Malcolm S
Program in Evolutionary Biology and Ecology, Department of Biology, University of Houston, Houston, TX 77204-5513, USA, , , , , , US.
Oecologia. 1998 Nov;117(1-2):143-150. doi: 10.1007/s004420050642.
Competition for space is an important process on tropical coral reefs. Few studies have examined the role sponges play in community structure despite the fact that many sponges are competitively superior to reef-building corals in space acquisition. Surveys conducted throughout the Florida Keys indicated that Chondrilla nucula was involved in about 30% of all coral-sponge interactions; this sponge has also been observed in 40-50% of coral-sponge interactions on other Caribbean reefs. C. nucula is also the top prey item of the Hawksbill turtle, and among the preferred prey of several spongivorous fish. I examined how predation influenced sponge competitive abilities (particularly those of C. nucula), and whether this type of indirect effect had important consequences for community dynamics in the Florida Keys. Exclusion of sponge predators (primarily angelfish) resulted in increased sponge overgrowth, with a subsequent greater loss of coral cover, compared to uncaged pairwise interactions. When caged, the corals Dichocoenia stokesii and Siderastrea sideraea lost significantly greater surface area and number of polyps to the sponge C. nucula compared to uncaged interactions. For caged interactions involving the sponge Ectyoplasia ferox, there was a trend for greater loss of S. sideraea surface area and polyps compared to uncaged interactions. Predation had a greater affect on C. nucula than on any of the other sponges examined. Predator exclusion experiments performed with naturally occurring coral-sponge interactions demonstrated a significant decrease in total coral cover compared to uncaged controls. It is proposed that indirect effects arising from spongivory (especially consumption of C. nucula) may have large community consequences. Species diversity on Caribbean reefs may be maintained, at least in part, by spongivores.
对空间的竞争是热带珊瑚礁上的一个重要过程。尽管许多海绵在获取空间方面比造礁珊瑚更具竞争力，但很少有研究考察海绵在群落结构中所起的作用。在整个佛罗里达群岛进行的调查表明，核果软海绵（Chondrilla nucula）参与了约30%的所有珊瑚 - 海绵相互作用；在其他加勒比珊瑚礁上，这种海绵也出现在40 - 50%的珊瑚 - 海绵相互作用中。核果软海绵也是玳瑁的主要猎物，并且是几种食海绵鱼类的首选猎物之一。我研究了捕食如何影响海绵的竞争能力（特别是核果软海绵的竞争能力），以及这种间接效应是否对佛罗里达群岛的群落动态产生重要影响。与未加笼的成对相互作用相比，排除海绵捕食者（主要是神仙鱼）导致海绵过度生长增加，随后珊瑚覆盖损失更大。当加笼时，与未加笼的相互作用相比，珊瑚斯托克斯角孔珊瑚（Dichocoenia stokesii）和铁星珊瑚（Siderastrea sideraea）因核果软海绵而损失的表面积和珊瑚虫数量显著更多。对于涉及多刺外胚叶海绵（Ectyoplasia ferox）的加笼相互作用，与未加笼的相互作用相比，铁星珊瑚的表面积和珊瑚虫损失有增加的趋势。捕食对核果软海绵的影响比对所研究的任何其他海绵都更大。对自然发生的珊瑚 - 海绵相互作用进行的捕食者排除实验表明，与未加笼的对照相比，总珊瑚覆盖率显著降低。有人提出，食海绵行为（特别是对核果软海绵的捕食）产生的间接效应可能对群落有重大影响。加勒比珊瑚礁上的物种多样性可能至少部分地由食海绵动物维持。
