Predation on postlarvae and juveniles of the shore crab Carcinus maenas: importance of shelter, size and cannibalism
Predation on postlarvae and juveniles of the shore crab Carcinus maenas: importance of shelter, size and cannibalism
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对岸蟹 Carcinus maenas 幼体和幼体的捕食：庇护所、体型和同类相食的重要性
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发表时间：
1998
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影响因子：
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通讯作者：
J. Montfrans
中科院分区：
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作者：
P. Moksnes;L. Pihl;J. Montfrans
由于捕食死亡率高，定居和幼体阶段被认为是许多底栖动物生活史上的一个瓶颈。托儿所栖息地可通过提供躲避捕食而在减少定居和定居后死亡率方面发挥重要作用。我们在实验室和野外的拴系实验中，研究了沿海蟹幼体和早期幼体的这些关系。我们研究了瑞典西海岸浅层(0到1米)软底托儿所常见的几个栖息地中与栖息地和大小有关的栖息地死亡率，这些栖息地以幼蟹和幼蟹为猎物，包括幼蟹。在开阔的沙地上定居死亡率很高(80%至90%)，而在贻贝床、鳗草和丝状绿藻获得了重要的栖息地避难所，后者的死亡率最低(13%至14%)。短命大型藻类结构复杂性的微小差异极大地影响了一龄蟹的捕食死亡率，只有中等复杂性的藻类才能获得显著的避难所。野外对被拴蟹的捕食率很高(52%~67%)，只有最小的蟹(甲壳宽度为5 mm，CW)，与开阔的沙滩相比，它在鳗草栖息地获得了显著的庇护。较大的螃蟹(5到25 mm CW)的死亡率很低(<；10%)，在沙地和鳗草栖息地类似。我们的结果表明，捕食是一个重要的过程，在栖息地的可用性的调节下，在定居和早期幼体阶段，捕食可能会对幼年岸蟹种群造成瓶颈。仔蟹在几个不同的栖息地获得了躲避捕食的避难所，这表明幼蟹的招募不会受到任何单一栖息地类型的时间和空间变化的影响。CW大于4 mm的蟹类栖息地大小较大，表明关键捕食者较小。我们认为，食人幼体的捕食率与所有其他被调查的捕食者相似或高于所有其他被调查的捕食者，是在育苗区安置幼蟹和幼蟹的优势捕食者。我们进一步提出，小型表层底栖捕食者对栖息地和大小特定的捕食是幼虫选择栖息地和幼虫利用栖息地的个体发育变化的重要选择力量。
Settlement and early juvenile stages are considered a bottleneck in the Life history of many epibenthic organisms because of high predation mortality. Nursery habitats may play an important role in mitigating settlement and post-settlement mortality by providing refuge from predation. We examined these relationships in postlarvae and early juvenile stages of the shore crab Carcinus maenas L. in laboratory and field tethering experiments. We studied habitat and size related habitat mortality using postlarvae and young juvenile crabs as prey, and various predators, including juvenile conspecifics, in several habitats common in shallow (0 to 1 m) soft bottom nursery areas on the Swedish west coast. Settling mortality was high in open sand (80 to 90%), whereas a significant habitat refuge was obtained in mussel beds, eelgrass and filamentous green algae, the latter yielding the lowest mortality (13 to 14%). Small differences in structural complexity of ephemeral macroalgae dramatically affected predation mortality of first instar crabs, with a significant refuge obtained only in algae of medium complexity. Predation rate on tethered crabs in the field was high (52 to 67%) only on the smallest crabs (<5 mm carapace width, CW), which obtained a significant refuge in the eelgrass habitat compared to open sand. Mortality for larger crabs (5 to 25 mm CW) was low (<10%) and similar in sand and eelgrass habitats. Our results indicate that predation is an important process that can create a bottleneck for juvenile shore crab populations during settlement and early juvenile stages, mediated by the availability of nursery habitats. Postlarvae obtained refuge from predation in several different habitats, suggesting that the recruitment of juvenile shore crabs will be less affected by temporal and spatial variation of any single habitat type. The strong size refuge for crabs larger than 4 mm CW indicates that key predators are small. We suggest that cannibalistic juveniles, which caused predation rates similar to or higher than all other investigated predators, are dominant predators on settling postlarvae and young juvenile crabs in nursery areas. We further propose that habitat- and size-specific predation by small epibenthic predators are an important selective force in habitat selection by postlarvae and ontogenetic shifts in habitat use by juveniles.