Abstract While many studies have examined the effects of flooding on earthworm population distributions, few studies have investigated physiological and behavioural responses of earthworms to the low oxygen conditions caused by flooding. An earthworm's skin is its oxygen exchange organ, allowing earthworms to survive in flooded environments provided that the water contains sufficient dissolved oxygen. Individuals of three species of earthworm, the anecic Lumbricus terrestris (Linneaus, 1758), the green morph of the endogeic Allolobophora chlorotica (Savigny, 1826) and the epigeic Lumbricus castaneus (Savigny, 1826) were placed in reconstituted groundwater that was either kept aerated or kept in a sealed container so that dissolved oxygen was gradually consumed as the earthworm respired. Oxygen saturation of the water was measured over time in sacrificial triplicate replicates from each treatment at discrete time points; earthworm mortality and mass were recorded. Before treatments, oxygen levels in all treatment tubes were 9.53 (±0.64) mg O2 L−1. L. terrestris, a large species which emerges at night to forage at the soil surface died when oxygen levels reached 0.82 (±0.46) mg O2 L−1 after approximately 36 h. L. castaneus, a smaller species which lives on the soil surface, died when oxygen levels reached 3.60 (±2.01) mg O2 L−1 after approximately 168 h. A. chlorotica, which is similar in size to L. castaneus, lives in the upper 20 cm of soil and is known to aestivate during the summer, did not die, even when oxygen levels reached 1.49 (±0.40) mg O2 L−1 after 280 h. The results suggest that earthworm respiration is closely linked to both body size and to behavioural ecotype. These findings suggest that if flooding increases in frequency resulting in episodic reductions in soil oxygen levels, the species composition of earthworm communities may change, with an increased presence of endogeic earthworms which show a responsive plasticity to flooding events.

中文翻译：

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淹水土壤中土壤动物生存的种间变异

摘要 虽然许多研究已经研究了洪水对蚯蚓种群分布的影响，但很少有研究调查蚯蚓对洪水引起的低氧条件的生理和行为反应。蚯蚓的皮肤是它的氧气交换器官，只要水中含有足够的溶解氧，蚯蚓就可以在被淹没的环境中生存。三种蚯蚓的个体，即无毛蚯蚓（Lumbricus terrestris，Linneaus，1758 年）、内生植物绿变色龙（Alolobophora chlorotica，Savigny，1826 年）和上生蚯蚓（Lumbricus castaneus，Savigny，1826 年）的个体被放置在重建的地下水中或保存在密封容器中，使溶解氧随着蚯蚓呼吸而逐渐消耗。水的氧饱和度随着时间的推移在离散时间点的每个处理中以一式三份的牺牲性重复进行测量；记录蚯蚓死亡率和质量。治疗前，所有治疗管中的氧气水平为 9.53 (±0.64) mg O2 L-1。L. terrestris，一种夜间出现在土壤表面觅食的大型物种，当氧气水平在大约 36 小时后达到 0.82 (±0.46) mg O2 L−1 时死亡。L. castaneus 是一种生活在土壤表面的较小的物种，在大约 168 小时后氧气水平达到 3.60 (±2.01) mg O2 L−1 时死亡。A. chlorotica 的大小与 L. castaneus 相似，生活在土壤的上层 20 cm 中，已知在夏季夏眠，即使氧气水平达到 1.49 (±0.40) mg O2 L−1 也不会死亡280 小时后。结果表明，蚯蚓呼吸与体型和行为生态型密切相关。这些研究结果表明，如果洪水频率增加导致土壤氧水平偶发性降低，蚯蚓群落的物种组成可能会发生变化，随着内生蚯蚓的存在增加，这些蚯蚓对洪水事件表现出响应的可塑性。