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首页> 外文期刊>Marine ecology progress series >Community-wide decline in the occurrence of lesser sandeels Ammodytes marinus in seabird chick diets at a North Sea colony
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Community-wide decline in the occurrence of lesser sandeels Ammodytes marinus in seabird chick diets at a North Sea colony

机译：在北海殖民地，海鸟雏鸡日粮中较少的三色A（Ammodytes marinus）发生率在整个社区范围内下降

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Many pelagic marine ecosystems have a wasp-waist trophic structure characterised by low diversity of mid-trophic species, typically small, shoaling forage fish that are eaten by a wide range of top predators. In the North Sea, this mid-trophic position is occupied by the lesser sandeel Ammodytes marinus. Over the last 30-40 yr, the abundance and length-at-age of sandeels have declined, but information on concurrent changes in the diets of seabird communities is scarce. We used data on chick diet composition, sandeel length-at-age and energy density collected at a colony in the western North Sea from 1973-2015, to test for dietary shifts in this seabird community during a period when a local sandeel fishery opened, operated and was closed. We found a long-term decline in the overall importance (measured as the frequency of occurrence and proportion of biomass in diet samples) of sandeels, particularly 1+ group fish. However, there were species-specific differences such that the overall decline in sandeels was strongest in common guillemots Uria aalge, while the shift from 1+ group to 0 group sandeels was apparent in all species except European shags Phalacrocorax aristotelis. Community-level differences were also apparent in the alternative prey to sandeels, with with common guillemot, razorbill Alca torda, Atlantic puffin Fratercula arctica, and black-legged kittiwake Rissa tridactyla chicks being fed clupeids, predominantly sprat Sprattus sprattus, while shag chicks received a wide range of benthic fish species. There was also evidence for a decline in the quality of sandeels fed to chicks with significant decreases in length-at-age of 0 group and 1+ group. However, there was no significant annual variation in the energy density of sandeels except for 2004, when values were exceptionally low. Neither the opening nor the closing of the sandeel fishery had any detectable effect on chick diet composition, sandeel length or sandeel energy density. Overall, our results suggest marked community-level changes in seabird diet composition over the last 3 decades that may reflect long-term declines in the abundance and quality of their principal prey.
机译：许多中上层海洋生态系统具有黄蜂腰部营养结构，其特征是中营养物种的多样性较低，这些物种通常是小型，浅滩觅食的鱼类，可被各种顶级捕食者捕食。在北海，这个中层营养位置被较小的三色沙A（Ammodytes marinus）占据。在过去的30至40年中，沙e的丰度和成虫的年龄有所下降，但是缺乏有关海鸟群落饮食同时变化的信息。我们使用了1973-2015年在北海西部一个殖民地收集的雏鸡饮食组成，桑德尔长寿年龄和能量密度的数据，测试了当地桑德尔渔业开放期间该海鸟群落的饮食变化，经营并关闭。我们发现，沙滩鞋，特别是1+组鱼类的总体重要性（以日粮中生物量的发生频率和比例）的长期重要性下降。但是，存在特定物种的差异，以使普通海雀科的乌里亚藻中的沙decline总体下降最强，而除欧洲粗毛Ph（Phalacrocorax aristotelis）以外的所有物种中，从1+组到0组的转变都显而易见。群落水平的差异在替代sand的猎物中也很明显，常见的有海雀科的,、剃刀b，美洲海鹦，大西洋海雀Fratercula arctica和黑腿的Kittiwake Rissa tridactyla雏鸡被喂食丘比丘鱼，主要是西鲱，而粗毛鸡被捕食。底栖鱼类种类繁多。也有证据表明，饲喂雏鸡的桑e品质下降，0岁组和1+组的成年期显着下降。但是，除了2004年的数值非常低外，沙滩鞋的能量密度没有明显的年度变化。开启和关闭桑德尔渔业对雏鸡的日粮组成，桑德尔长度或桑德尔能量密度都没有可检测到的影响。总体而言，我们的结果表明，在过去的30年中，海鸟饮食组成出现了社区层面的显着变化，这可能反映了其主要猎物的丰度和质量长期下降。

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