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首页> 外文期刊>Estuarine Coastal and Shelf Science >Trophic ecology of Magellanic penguins (Spheniscus magellanicus) during the non-breeding period
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Trophic ecology of Magellanic penguins (Spheniscus magellanicus) during the non-breeding period

机译：非繁殖期麦哲伦企鹅（Spheniscus magellanicus）的营养生态

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摘要

Some top predators couple their migration with the migration of their main prey. Magellanic penguins, Spheniscus magellanicus, migrate north from their Patagonian colonies during their non-breeding period, supposedly following the Argentine anchovy, Engraulis anchoita, a keystone species and their main prey item in the southwestern Atlantic Ocean. However, previous studies based on stranded carcasses suggest that cephalopods are the main food item for the penguins at their Brazilian wintering grounds. Moreover, anchovy stocks are in the early stages of commercial exploitation in southern Brazil. This study aims to investigate the importance of the Argentine anchovy in the diet of Magellanic penguins, including penguins of different age classes, both healthy and debilitated individuals, and in different parts of their annual cycle, using stomach content analysis and stable isotope analysis of multiple tissues, representing different time windows. Juvenile and adult penguins were collected(n = 54), either stranded on the beach or incidentally killed during gillnet fishing in adjacent waters. Penguins collected at sea had higher body mass indexes compared to stranded, demonstrating that they were healthy individuals. Among adult penguins from both areas (n = 21), fish was the main food item in their stomachs (prey-specific index of relative importance, PSIRI = 86%), with high contribution of Argentine anchovy. Cephalopods were the main food item (PSIRI = 71%) for juveniles (n = 20), with a predominance of the squid Doryteuthis sanpaulensis. In liver, muscle and feathers of penguins, mixed models based on delta C-13 and delta N-15 values demonstrated large contribution of the Argentine anchovy in the diet of the juveniles (95% credibility interval = 46-98.6%) and adults (39.8-98.9%), despite the high importance of cephalopods in the juvenile diet as identified in the stomach content analysis. Adults and juveniles presented isotopic niche overlap for all the tissues analysed, despite the differences in isotopic niche areas (= niche width) among the age classes. In 29% of the stomach contents, plastic debris was also found. Our results highlight the importance of using complementary techniques to study trophic ecology, as stomach content analysis of individuals found dead on beaches may not provide reliable information on diet. The strong reliance of penguins on the Argentine anchovy as a key resource throughout its annual cycle suggests that the stocks of this small pelagic fish should be exploited sustainably, ensuring the minimal forage biomass needed not only for seabirds but also for other consumers.
机译：一些顶级掠食者将其迁徙与主要猎物的迁徙结合在一起。麦哲伦企鹅（Spheniscus magellanicus）在非繁殖时期从巴塔哥尼亚殖民地向北迁移，据推测是继阿根廷an鱼Engraulis anchoita（基石物种及其西南大西洋的主要猎物）之后。但是，先前基于搁浅的car体的研究表明，在巴西的越冬地，头足类是企鹅的主要食物。此外，在巴西南部，cho鱼种群处于商业开发的初期。这项研究旨在通过胃内容物分析和多种元素的稳定同位素分析，研究阿根廷an鱼在麦哲伦企鹅饮食中的重要性，包括不同年龄类别的企鹅（包括健康人和虚弱的个体）以及他们年周期的不同部分组织，代表不同的时间窗口。收集了幼企鹅和成年企鹅（n = 54），它们要么滞留在海滩上，要么在相邻水域的刺网捕鱼中被偶然杀死。与搁浅相比，在海上收集的企鹅具有更高的体重指数，表明它们是健康的个体。在这两个地区的成年企鹅中（n = 21），鱼类是其胃中的主要食物（相对重要性的特定猎物指数，PSIRI = 86％），其中阿根廷an鱼的贡献很大。头足类是少年（n = 20）的主要食物（PSIRI = 71％），其中以鱿鱼Doryteuthis sanpaulensis居多。在企鹅的肝脏，肌肉和羽毛中，基于ΔC-13和ΔN-15值的混合模型证明了阿根廷an鱼在青少年（95％可信区间= 46-98.6％）和成年人（ 39.8-98.9％），尽管头足类动物在胃内容物分析中确定在青少年饮食中具有很高的重要性。尽管各个年龄段的同位素生态位区域（=生态位宽度）不同，但成年人和青少年的所有组织的同位素生态位重叠。在29％的胃内容物中还发现了塑料碎片。我们的研究结果突出了使用互补技术研究营养生态学的重要性，因为对在海滩上死亡的人进行的胃含量分析可能无法提供有关饮食的可靠信息。企鹅在整个年度周期中都非常依赖阿根廷an鱼作为主要资源，这表明应持续开发这种中上层鱼类的种群，以确保不仅为海鸟而且为其他消费者所需的最低饲料生物量。

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