Babbitt Kimberly J, Tanner George W
Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, USA, , , , , , US.
Oecologia. 1998 Apr;114(2):258-262. doi: 10.1007/s004420050444.
Size-limited predation is an important process during the development of many aquatic species, and mortality rates of early larval stages and small individuals can be particularly high. Structurally complex habitats can mediate predator-prey interactions and provide a potentially important mechanism for decreasing predation pressure on larvae. To determine whether structurally complex habitats mediate predation on tadpoles of the southern leopard frog (Ranautricularia), we designed a factorial experiment, crossing two levels of cover with three predator treatments (none, small, or large Trameacarolina naiads). Predator size had a larger effect on tadpole performance (survival, mass and age at metamorphosis) than did cover level, largely because small predators were ineffective. Within the large-predator treatment, however, tadpole survival was higher (78%) under high than under low cover (46%), suggesting that increased cover decreased predator foraging efficiency allowing more larvae to reach a size refuge. This study demonstrates that habitat structural complexity can play an important role in mediating predator-prey interactions, even when tadpoles start out at a size disadvantage relative to predators. Consideration of habitat structural complexity in future research should provide a more complete understanding of the role of size relationships in predator-prey systems.
体型限制捕食是许多水生物种发育过程中的一个重要过程，早期幼体阶段和小型个体的死亡率可能特别高。结构复杂的栖息地可以调节捕食者与猎物之间的相互作用，并提供一种潜在的重要机制来降低对幼体的捕食压力。为了确定结构复杂的栖息地是否能调节对南部豹蛙（赤蛙）蝌蚪的捕食，我们设计了一个析因实验，将两种遮蔽程度与三种捕食者处理方式（无、小型或大型卡罗莱纳螯虾若虫）进行交叉组合。捕食者的体型对蝌蚪的表现（存活、变态时的体重和年龄）的影响比遮蔽程度更大，这主要是因为小型捕食者效率低下。然而，在大型捕食者处理组中，高遮蔽度下蝌蚪的存活率（78%）高于低遮蔽度下（46%），这表明增加遮蔽度会降低捕食者的觅食效率，使更多幼体能达到体型庇护所。这项研究表明，栖息地结构复杂性在调节捕食者与猎物之间的相互作用中可以发挥重要作用，即使蝌蚪相对于捕食者一开始在体型上处于劣势。在未来的研究中考虑栖息地结构复杂性，应该能更全面地理解体型关系在捕食者 - 猎物系统中的作用。
