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首页> 外文期刊>ICES Journal of Marine Science >How fishing intensity affects the spatial and trophic ecology of two gull species breeding in sympatry
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How fishing intensity affects the spatial and trophic ecology of two gull species breeding in sympatry

机译：捕捞强度如何影响共生中两种海鸥繁殖的空间和营养生态

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Fisheries produce large quantities of discards, an important resource for scavenging seabirds. However, a policy reform banning discards, which is soon to be implemented within the EU, will impose a food shortage upon scavengers, and it is still largely unknown how scavengers will behave. We studied the diet (hard remains), trophic (stable isotope analysis), and foraging (individual tracking) ecology of two gull species breeding in sympatry: Audouin's gull Larus audouinii (AG) and yellow-legged gull Larus michahellis (YLG), in South Portugal, under normal fishery activity (NFA; work days) and low fishery activity (LFA; weekends), over two consecutive years. We established a pattern of dietary, spatial, and temporal segregation between the two gull species. Under LFA, yellow-legged gulls reduced their time spent at-sea, thus foraging more in alternative habitats (e. g. refuse dumps) and widening their isotopic niche (i. e. generalist behaviour). Contrastingly, Audouin's gull had a narrower trophic niche (i. e. specialist behaviour), foraging exclusively at-sea, reducing the amount of demersal fish and increasing the amount of pelagic fish in their diet. Under NFA, both species foraged mostly at-sea, feeding almost exclusively on fish, with increased consumption of demersal species (i. e. fishery discards). In general, yellow-legged gull had a broader trophic niche (i. e. generalist behaviour) when compared with the narrower isotopic niche of Audouin's gull (i.e. specialist behaviour). Overall, both gull species relied heavily on fishery discards. However, there was visible dietary, spatial, and temporal segregation between the two species, associated with their dietary and habitat preferences that could be attributed to the availability of anthropogenic resources, such as fishery discards.
机译：渔业产生大量的丢弃物，这是清除海鸟的重要资源。但是，一项即将在欧盟内部实施的禁止丢弃物的政策改革将使拾荒者面临粮食短缺的问题，而且拾荒者的行为方式仍是未知之数。我们研究了两种在共生中繁殖的海鸥物种的饮食（坚硬的残留物），营养（稳定的同位素分析）和觅食（个体追踪）生态：Audouin的鸥Lauru audouinii（AG）和黄腿鸥Larus michahellis（YLG），连续两年处于正常渔业活动（NFA;工作日）和低渔业活动（LFA;周末）的葡萄牙南部。我们建立了两种海鸥在饮食，空间和时间上的隔离模式。在LFA下，黄腿鸥减少了在海上的停留时间，因此在替代生境中觅食更多（例如垃圾场），并拓宽了它们的同位素生态位（即通俗行为）。相反，Audouin的海鸥具有较窄的营养生态位（即专业行为），仅在海上觅食，减少了深海鱼类的数量，并增加了其饮食中上层鱼类的数量。在NFA模式下，这两种物种大多在海上觅食，几乎全部以鱼为食，而沉水物种（即渔业丢弃物）的消费量增加。通常，与Audouin鸥的窄同位素生态位（即专业行为）相比，黄腿鸥具有更宽的营养位（即通才行为）。总体而言，这两种海鸥物种都严重依赖渔业丢弃物。但是，这两个物种之间在饮食，空间和时间上存在明显的隔离，这与它们的饮食和生境偏好有关，这可能归因于人为资源的可获得性，例如渔业丢弃物。

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