Quantification of abundance and food consumption of seabirds are key to understand characteristics and ecological functions of local marine ecosystem due to their abundance and diversity in foraging areas, habitat, behavior, mobility and prey types. This study aimed to quantify seabird abundance in pelagic areas in the eastern Indian sector of the Southern Ocean (80–150E°) based on an at-sea observational study conducted during the 2018/19 austral summer season. We estimated food consumption by seabirds based on their biomass, estimated field metabolic rates, number of days spent in the areas, and diet composition. Among the five functional seabird groups (penguins, albatrosses/giant petrels, shearwaters, petrels/Charadriiformes, prions/storm-petrels), shearwaters, non-Antarctic resident, were the most dominant taxa both by abundance (15,650,000 birds) and biomass (9,332 tonnes) in the study area during the summer. Most of the prey consumed by all seabirds in the area was presumed to be Antarctic krill (55,504 tonnes) and pelagic fishes (91,695 tonnes), such as myctophids. Although the total food consumption by the seabirds during the summer (209,973 tonnes) was lower than that reported in the Antarctic neritic areas (e.g., 753,000 tonnes in the neighboring Prydz Bay region), the higher proportion of non-resident shearwaters in biomass and estimated food consumption (85%) were the characteristic of the study area. Our results highlight the characteristics of the ecological importance of the study area in which seabirds consume Antarctic krill and pelagic fishes in the upper layer of the water column, and its nutrients are easily transported by the seabirds as their subcutaneous fat or stomach oil to the outside of the areas.

中文翻译：

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南大洋东印度海域中上层生态系统中海鸟的丰度和估计食物消费量


由于海鸟在觅食区域、栖息地、行为、流动性和猎物类型的丰富性和多样性，量化海鸟的丰度和食物消耗是了解当地海洋生态系统特征和生态功能的关键。本研究旨在根据 2018/19 年南半球夏季进行的海上观测研究，量化南大洋东印度部分 （80-150E°） 中上层区域的海鸟丰度。我们根据海鸟的生物量、估计的野外代谢率、在该地区停留的天数和饮食成分来估计海鸟的食物消耗量。在五个功能性海鸟类群（企鹅、信天翁/巨型海燕、海鸥、海燕/Charadriiformes、朊病毒/风暴海燕）中，海鸥是非南极居民，在夏季研究区域的丰度（15,650,000 只鸟）和生物量（9,332 吨）方面是最主要的分类群。据推测，该地区所有海鸟吃掉的大部分猎物是南极磷虾（55,504 吨）和中上层鱼类（91,695 吨），例如真菌蚜虫。尽管海鸟在夏季的总食物消耗量（209,973 吨）低于南极神经区报告的水平（例如，邻近的 Prydz 湾地区的 753,000 吨），但非居民海鸥在生物量中的比例较高，估计食物消耗量 （85%） 是研究区域的特征。我们的研究结果突出了研究区的生态重要性特征，其中海鸟食用水柱上层的南极磷虾和中上层鱼类，其营养物质很容易被海鸟作为皮下脂肪或胃油输送到区域外。