Our understanding of the ecology of the hadal zone (> 6000 m depth) is based solely on subduction trenches, leaving other geomorphological features, such as fracture zones, troughs, and basins, understudied. To address this knowledge gap, the Wallaby-Zenith Fracture Zone, Indian Ocean (WZFZ; ~ 22°S, 102°E; maximum depth 6625 m measured during Expedition SO258) was studied using free-fall baited landers. We assessed the amphipod distribution and community assemblage of this non-subduction hadal feature and compared it to subduction hadal features. Eleven species were identified across the abyssal-hadal transition zone using a paired morphological and DNA barcoding approach. The community composition was found to change gradually from abyssal to hadal depths, which contrasts with the ecotone shift characteristic of subduction trenches. A large population of Bathycallisoma schellenbergi (Birstein & Vinogradov, 1958), a quintessential hadal amphipod, was present at the flat bottom of the WZFZ. Further, an mtDNA phylogeny resolved a degree of phylogeographic structure between the B. schellenbergi WZFZ population and four previously sampled Pacific Ocean subduction trench populations, indicating these features are not interconnected through ongoing gene flow. Combined, these data indicate that some amphipods have far broader distributions than previously understood, with some species present in both hadal subduction trenches and non-subduction fracture zones and basins interspersed across the abyssal plains. This initial exploration highlights that whilst non-subduction features are an overlooked minor fraction of the total hadal area, they are essential to our understanding of the ecological and evolutionary dynamics across the hadal zone.

我们对海底带（> 6000 m深度）生态学的理解仅基于俯冲沟，而未研究其他地貌特征，例如裂缝带，槽和盆地。为了解决这一知识鸿沟，我们使用自由落下的诱饵着陆器研究了印度洋的Wallaby-Zenith断裂带（WZFZ；〜22°S，102°E；在Expedition SO258期间测得的最大深度6625 m）。我们评估了这种非俯冲哈德勒特征的两栖动物分布和群落组合，并将其与俯冲哈德勒特征进行了比较。使用配对的形态学和DNA条形码方法，在深海-哈德河过渡带发现了11种物种。发现群落组成从深渊到海底深度逐渐变化，这与俯冲沟的过渡带移动特征形成鲜明对比。WZFZ的平坦底部有一个典型的长柄双足纲脚目贝氏call虫（Birstein＆Vinogradov，1958年）。此外，mtDNA的系统发育分析解决了Schellenbergi B.之间的一定程度的植物学结构WZFZ种群和四个先前采样的太平洋俯冲海沟种群，表明这些特征没有通过正在进行的基因流相互联系。综合起来，这些数据表明，某些两栖类动物的分布比以前理解的要广得多，一些物种存在于俯冲沟和非俯冲断裂带以及盆地中，遍布整个深渊平原。最初的探索突显出，虽然非俯冲特征仅占整个海底面积的一小部分，但它们对于我们了解整个海底带的生态和演化动态至关重要。