The introduction of nonnative species is one of the most critical problems facing freshwater systems today. The rivers of the Great Basin (USA) have been particularly imperiled by nonnative species introductions and represent a valuable location to study the dietary trends of native and nonnative fishes in isolated, endorheic systems. We collected fish from 23 sites, spanning three Great Basin watersheds (Carson, Humboldt, and Bear Rivers) and two elevation categories (upland and lowland). Only a single species (speckled dace Rhinichthys osculus) occurred in both elevation zones. Diet item analyses of over 500 fish stomachs indicated significant dietary overlaps between native and nonnative fishes and detailed dietary selectivity for all species. This finding, along with the low species diversity observed in the region, suggests low dietary niche diversity, which could have the potential to amplify the competitive impacts of nonnatives on native species. In upland sites, nonnative trouts were the dominant invaders, while in lowland sites warm-water nonnatives were prevalent. The management implications we recommend based on our results urge for continued monitoring of water temperature and species occurrences to predict if dietary overlaps observed in this study are likely to change in the future. This article is protected by copyright. All rights reserved.

中文翻译：

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内陆河鱼类的饮食特异性和重叠：本地和非本地物种如何比较？

非本地物种的引入是当今淡水系统面临的最关键问题之一。大盆地（美国）的河流特别受到外来物种引入的威胁，是研究孤立的内陆系统中本地和非本地鱼类饮食趋势的宝贵地点。我们从 23 个地点收集鱼类，跨越三个大盆地流域（卡森河、洪堡河和贝尔河）和两个海拔类别（高地和低地）。只有一个物种（斑点鲇鱼 osculus）出现在两个海拔区域。对 500 多条鱼胃的饮食项目分析表明，本地和非本地鱼类之间存在显着的饮食重叠，并且对所有物种都有详细的饮食选择性。这一发现，连同在该地区观察到的低物种多样性，表明低饮食生态位多样性，这可能有可能放大非本地物种对本地物种的竞争影响。在高地地区，外来鳟鱼是主要入侵者，而在低地地区，温水非本地人则普遍存在。我们根据我们的结果推荐的管理影响敦促继续监测水温和物种的出现，以预测本研究中观察到的饮食重叠是否可能在未来发生变化。本文受版权保护。版权所有。我们根据我们的结果推荐的管理影响敦促继续监测水温和物种的出现，以预测本研究中观察到的饮食重叠是否可能在未来发生变化。本文受版权保护。版权所有。我们根据我们的结果推荐的管理影响敦促继续监测水温和物种的出现，以预测本研究中观察到的饮食重叠是否可能在未来发生变化。本文受版权保护。版权所有。