Abstract Procambarus clarkii is an important invasive freshwater species whose ecological plasticity allows for its establishment in different kinds of environments; such plasticity is also reflected in its diet with two main consequences: invasion success and impact on native biota. In order to investigate P. clarkii’s feeding habits, examine how its diet varies both seasonally and among different demographic groups (reproductive males, non-reproductive males and females) and explore the two consequences mentioned above, we investigated the trophic role of this species in an Atlantic Forest conservation area in the city of Sao Paulo (Brazil). A total of 540 specimens collected monthly over a year were measured and weighed. Their stomachs were weighed and classified according to the degree of stomach fullness. Stomach contents were examined, and animal and plant matter weighed. Food items were identified to the lowest possible taxonomic level and the percentage of occurrence of each item was calculated, as well as the diet diversity. Collected data were compared according to seasons and demographic groups through the Analysis of Similarity and Similarity Percentage Analysis. The percentage of animal weight attributed to stomach weight and the degree of fullness of stomachs did not vary significantly among seasons; however, non-reproductive males had significantly less full stomachs. Diet composition was evenly balanced between plant and animal material for both reproductive males and females, while non-reproductive males consumed a lower proportion of animal matter. The diversity in diet composition was high in all seasons and for all demographic groups, although always slightly lower for non-reproductive males. The percentage of occurrence of food items evidenced high consumption of algae and macrophytes throughout the year. It also reflected the seasonal variation of consumed prey, with a shift in consumption of insects and microcrustaceans in spring and summer to decapods and amphibians in fall and winter. The dissimilarity in diet composition was more pronounced among demographic groups than among seasons, being non-reproductive males the most different, with higher ingesting of less evasive prey. Nonetheless, winter differed from other seasons and was the season with least different food composition among demographic groups, indicating a homogenization in diet composition, which might be due to restricted availability of resources. Procambarus clarkii at Jaragua State Park demonstrated conspicuous dietary variability and flexibility. The occurrence of filled stomachs indicates that food resources are not a constriction for this population. The species presented a diversified and adaptable diet, foraging on algae and macrophytes, and preying on different vertebrate and invertebrate taxa. Its trophic plasticity favors successful establishment in invaded areas and summed to its notable voracity, P. clarkii offers a wide, variable and significant interaction in food webs, being able to generate major impacts on native species by its feeding habits.

中文翻译：

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食物问题：营养动力学和饮食在大西洋森林保护区 Procambarus clarkii 入侵成功中的作用

摘要 克拉克原螯虾是一种重要的淡水入侵物种，其生态可塑性使其能够在不同环境中生存；这种可塑性也反映在它的饮食中，主要有两个后果：入侵成功和对本地生物群的影响。为了调查 P. clarkii 的摄食习惯，检查其饮食在季节性和不同人口群体（有生殖雄性、非生殖雄性和雌性）之间的变化，并探讨上述两个后果，我们调查了该物种在位于巴西圣保罗市的大西洋森林保护区。对一年内每月收集的总共 540 个样本进行了测量和称重。他们的胃被称重并根据胃饱的程度进行分类。检查胃内容物，和动物和植物物质称重。食品项目被确定为尽可能低的分类水平，并计算每个项目的出现百分比以及饮食多样性。通过相似性分析和相似性百分比分析，根据季节和人口统计组比较收集的数据。动物体重占胃重的百分比和胃的饱胀程度在不同季节之间没有显着差异；然而，非生殖雄性的饱腹感要低得多。生殖雄性和雌性的植物和动物材料之间的饮食成分均衡，而非生殖雄性消耗的动物材料比例较低。在所有季节和所有人口群体中，饮食构成的多样性都很高，尽管非生殖雄性总是略低。食品出现的百分比证明全年藻类和大型植物的消耗量很高。它还反映了食用猎物的季节性变化，春季和夏季的昆虫和微型甲壳类动物的食用量转变为秋季和冬季的十足目动物和两栖动物。与季节相比，人口群体之间饮食构成的差异更为明显，非生殖雄性的差异最大，对较少回避的猎物的摄入量更高。尽管如此，冬季与其他季节不同，并且是人口群体中食物成分差异最小的季节，表明饮食成分的同质化，这可能是由于资源有限。Jaragua 州立公园的 Procambarus clarkii 表现出显着的饮食可变性和灵活性。填饱肚子的出现表明食物资源不是这个人口的限制。该物种呈现出多样化和适应性强的饮食，以藻类和大型植物为食，捕食不同的脊椎动物和无脊椎动物分类群。P. clarkii 的营养可塑性有利于在入侵地区成功建立，总而言之，它具有显着的贪婪性，在食物网中提供广泛、可变和重要的相互作用，能够通过其摄食习惯对本地物种产生重大影响。以藻类和大型植物为食，捕食不同的脊椎动物和无脊椎动物分类群。P. clarkii 的营养可塑性有利于在入侵地区成功建立，总而言之，它具有显着的贪婪性，在食物网中提供广泛、可变和重要的相互作用，能够通过其摄食习惯对本地物种产生重大影响。以藻类和大型植物为食，捕食不同的脊椎动物和无脊椎动物分类群。其营养可塑性有利于在入侵地区成功建立，总而言之，它的显着贪婪性，P. clarkii 在食物网中提供广泛、可变和重要的相互作用，能够通过其摄食习惯对本地物种产生重大影响。