The Southern California Borderland hosts a variety of geologic and oceanographic features that allow for diverse habitats to occur in a restricted region with a strong oxygen minimum zone (OMZ) and hard substrates. These include ferromanganese (FeMn) crusts and phosphorites targeted for deep‐seabed mining in other regions. Baseline studies regarding hardground macro‐ (> 0.3 mm) and megafaunal (> 2 cm) invertebrates are lacking, although they contribute to understanding nutrient cycling and resilience of deep‐sea communities to ocean deoxygenation, fishing, or mineral extraction. With the goal of understanding how substrate type, depth, and dissolved oxygen concentration influence invertebrate trophic structure, we surveyed δ13C and δ15N values of invertebrates on hard substrates on the Southern California Borderland margin along a depth gradient (120–2400 m) through the OMZ at inshore (< 100 km from shore) and offshore (100–250 km from shore) sites, using generalized additive models and community‐level metrics. Macrofaunal isotopic values correlate with substrate type, exhibiting higher trophic diversity on FeMn crusts and specialized communities on phosphorites. Megafaunal isotopic values correlate with proximity to shore; animals offshore seem to depend more on phytoplanktonic production than animals inshore. In general, δ15N increased with decreasing dissolved oxygen and increasing depth, possibly due to remineralization processes within the OMZ and with depth. We discuss how feeding modes and community composition might influence the observed patterns. This study elucidates the importance of the environmental context in shaping invertebrate trophic structure on continental margins and provides baseline knowledge that may be useful in regions where these minerals are targeted for extraction.

中文翻译：

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海洋铁锰和磷矿硬质土壤上的无脊椎动物营养结构


南加州边境拥有多种地质和海洋特征，使得在具有强最低氧区 (OMZ) 和坚硬基质的限制区域内可以出现多种栖息地。其中包括铁锰（FeMn）结壳和磷矿，目标用于其他地区的深海海底采矿。关于大型硬地动物（> 0.3 毫米）和巨型动物（> 2 厘米）无脊椎动物的基线研究尚缺乏，尽管它们有助于了解深海群落的营养循环和对海洋脱氧、捕捞或矿物开采的恢复能力。为了了解基质类型、深度和溶解氧浓度如何影响无脊椎动物的营养结构，我们沿着 OMZ 的深度梯度 (120–2400 m) 调查了南加州边境边缘硬基质上无脊椎动物的 δ13C 和 δ15N 值在近海（距海岸 < 100 公里）和近海（距海岸 100-250 公里）地点，使用广义累加模型和社区级指标。大型动物同位素值与基质类型相关，在铁锰结壳上表现出更高的营养多样性，在磷矿上表现出专门的群落。巨型动物同位素值与距离海岸的距离相关；近海动物似乎比近海动物更依赖浮游植物的产生。一般来说，δ15N 随着溶解氧的减少和深度的增加而增加，这可能是由于 OMZ 内的再矿化过程和深度的影响。我们讨论喂养模式和群落组成如何影响观察到的模式。 这项研究阐明了环境背景在塑造大陆边缘无脊椎动物营养结构中的重要性，并提供了可能对这些矿物的开采目标地区有用的基线知识。