With increasing biodiversity loss occurring worldwide, there is a need to understand how these losses will affect ecosystem structure and function. Biodiversity loss leads to changes in species interactions and alters the trophic complexity of food webs. These alterations to trophic complexity can be described by changes to the diversity of food resources and the diversity of trophic levels. To understand how biodiversity affects trophic complexity of food webs, we used 10 islands across the Aleutian Archipelago to compare the alternate state communities found in kelp forest ecosystems (kelp forest and urchin barren communities) and then compared these to natural reference communities without local benthic production (their associated offshore communities). We constructed food webs for each community across the Aleutian Archipelago using primary producer and consumer carbon (δ¹³C, a proxy for food sources to a consumer) and nitrogen (δ¹⁵N, a proxy for consumer trophic level) stable isotope values. Our findings suggest that biodiversity loss (i.e., phase change from kelp forest to urchin barren) leads to reductions in trophic complexity, which was similar to naturally occurring communities with low local resource biodiversity. This was expressed by lower consumer isotopic dietary niche areas, especially omnivores and herbivores, and lower omnivore and carnivore trophic levels within the urchin barren communities. We clarify how biodiversity promotes food resources and increases trophic levels and complexity through critical trophic conduits.

中文翻译：

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生物多样性的丧失导致整个社区的营养复杂性降低

随着世界范围内生物多样性丧失的加剧，有必要了解这些丧失将如何影响生态系统的结构和功能。生物多样性的丧失导致物种相互作用的改变，并改变了食物网的营养复杂性。对营养复杂性的这些改变可以通过改变食物资源的多样性和营养水平的多样性来描述。为了了解生物多样性如何影响食物网的营养复杂性，我们使用了阿留申群岛上的10个岛屿来比较海带森林生态系统中发现的其他州社区（海带森林和海胆贫瘠社区），然后将其与没有当地底栖生物生产的自然参考社区进行比较。 （其相关的离岸社区）。¹³ C，食物来源到消费者）和氮的代理（δ ¹⁵ N，用于消费者营养级）稳定同位素值的代理。我们的发现表明，生物多样性的丧失（即，从海带森林到海胆贫瘠的相变）导致营养复杂性降低，这与当地生物多样性较低的自然界相似。较低的消费者同位素饮食生态位区域，尤其是杂食动物和食草动物，以及海胆贫瘠社区中的杂食动物和食肉动物营养水平较低，表明了这一点。我们阐明了生物多样性如何通过重要的营养通道来促进粮食资源并增加营养水平和复杂性。