Trophic niche analysis can be used to assess ecological opportunities available to alien species in areas of introduction that might aid their establishment, define their functional role and inform on their potential impacts. This study assessed the trophic niche utilized by an invasive population of the Australian redclaw crayfish, Cherax quadricarinatus, in the Inkomati River Basin, South Africa. It evaluated the hypothesis that the euryphagous feeding strategy of redclaw crayfish may allow it to shift its niche width and niche position by altering its feeding strategy in response to fluctuations in resource availability. Gut content and stable isotope analyses were used to determine trophic niche and trophic interactions. Redclaw crayfish were shown to be omnivores and their diet consisted mainly of algae, plant material and invertebrates. Small-sized individuals had a constricted niche width and fed primarily on invertebrates, whereas larger individuals expanded their niche width to include larger proportions of plant material. Crayfish caught from lotic environments had a higher proportion of invertebrates in their diet than crayfish from lentic environments, and the species exploited a wider niche in summer than in winter. These differences are likely related to differences in productivity amongst habitats and fluctuations in resource availability. There was significant niche overlap (>60%) between redclaw crayfish and Sidney's river crab (Potamonautes sidneyi), but not with other native invertebrates. Both species are omnivores and have similar functional roles, possibly making redclaw crayfish functionally redundant in this ecosystem. Even though both species mainly feed on resources (plant material and invertebrates) that are not normally limiting, the redclaw crayfish invasion might be an accelerator of ecosystem processes such as shredding and decomposition rates of plant material. There is, therefore, a need for further studies to examine potentially altered ecosystem functions caused by redclaw crayfish invasion in the Inkomati River system.

中文翻译：

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侵入性多面手消费者的营养生态位：南非因科马蒂河流域的澳大利亚红爪螯虾，Cherax quadricarinatus

营养生态位分析可用于评估外来物种在引进地区可利用的生态机会，这些机会可能有助于它们的建立，确定它们的功能作用并告知它们的潜在影响。本研究评估了澳大利亚红爪螯虾Cherax quadricarinatus的入侵种群利用的营养生态位，在南非因科马蒂河流域。它评估了一个假设，即红爪小龙虾的自食性摄食策略可能允许它通过改变其摄食策略来改变其生态位宽度和生态位位置以响应资源可用性的波动。肠道含量和稳定同位素分析用于确定营养生态位和营养相互作用。红爪小龙虾被证明是杂食动物，它们的饮食主要由藻类、植物材料和无脊椎动物组成。小型个体具有狭窄的生态位宽度，主要以无脊椎动物为食，而较大的个体扩大其生态位宽度以包括更大比例的植物材料。从流动环境中捕获的小龙虾在其饮食中的无脊椎动物比例高于从静止环境中捕获的小龙虾，并且该物种在夏季比冬季利用了更广泛的生态位。这些差异可能与栖息地之间生产力的差异和资源可用性的波动有关。红爪小龙虾和西德尼河蟹之间存在显着的生态位重叠（>60%）（Potamonautes sidneyi )，但不与其他本地无脊椎动物一起。这两个物种都是杂食动物，并且具有相似的功能作用，这可能使红爪小龙虾在这个生态系统中的功能变得多余。尽管这两个物种主要以通常不受限制的资源（植物材料和无脊椎动物）为食，但红爪小龙虾的入侵可能是生态系统过程的加速器，例如植物材料的切碎和分解速率。因此，需要进一步研究以检查因科马蒂河系统中红爪小龙虾入侵引起的潜在改变的生态系统功能。