Abstract：
Morphologically similar species that occupy resource-limited environments tend to differ in their ecological traits in order to coexist, which may result in differential exposure to environmental threats. For instance, partitioning of feeding resources may influence contaminant exposure and bioaccumulation in marine predators through different diets or foraging habitats. Here, we sampled three tropical seabird species breeding in sympatry in the southwestern Atlantic Ocean for blood and feather trace element concentrations (As, Hg, Cd, Pb), and assessed their foraging ecology with bio-logging (GPS tracks and time-depth recorders), analysis of regurgitated prey, and carbon and nitrogen stable isotope mixing models. Red-billed tropicbirds (Phaethon aethereus), brown (Sula leucogaster) and masked (S. dactylatra) boobies differed in their preferred foraging locations, the range of foraging trips, diving parameters and diets. In addition, interspecific differences were detected in blood or feathers for all trace elements analyzed, suggesting influence of the differences observed in diet and space use. Red-billed tropicbirds had the largest foraging range over the continental shelf and over the slope, suggesting lower exposure to continental sources of metals. Brown and masked boobies had higher Hg concentrations than tropicbirds, higher δ15N values (a proxy for trophic level), and δ15N correlated with Hg levels, suggesting biomagnification of Hg along the food chain. Nonetheless, red-billed tropicbirds showed comparable levels of As and Cd in blood or feathers, and higher levels of Pb in both tissues in comparison to boobies, which may suggest overall exposure of seabirds in the region, through their diets and foraging areas. Resource partitioning is critical for allowing coexistence of different seabird species in shared breeding sites where they act as central-place foragers. Nonetheless, in scenarios of environmental pollution, these species-specific strategies lead to differential bioaccumulation, and thus distinct effects of pollution on populations are expected.
摘要：
形态相似的物种占据资源有限的热带环境，其生态特征往往不同，以便共存，这可能导致对环境威胁的不同暴露。例如,饲料资源的分配可能会通过不同的饮食或觅食栖息地影响海洋顶端捕食者的污染物暴露和生物积累。这里,我们采样了西南大西洋共生中繁殖的三种热带海鸟物种的血液和羽毛微量元素浓度（As，Hg,Cd,Pb),并通过生物测井（GPS跟踪和时间深度记录仪）评估了它们的觅食生态，反流猎物的分析，以及碳和氮稳定同位素混合模型。红嘴热带鸟（Phaethonaethereus），棕色(苏拉leucogaster)和蒙面(S.dactylatra)胸部的首选觅食地点不同，觅食旅行的范围，潜水参数和饮食。此外,在血液或羽毛中检测到所有微量元素的种间差异，表明在饮食和空间使用中观察到的差异的影响。红嘴热带鸟类在大陆架和斜坡上的觅食范围最大，表明对大陆金属来源的接触较低。棕色和蒙面的鸟比热带鸟的汞浓度高，较高的δ15N值(营养级的代表)，δ15N与Hg水平相关，表明汞在食物链上的生物放大作用。尽管如此，尽管红嘴热带鸟类在更远的近海觅食，它们在血液或羽毛中的砷和镉含量相当，与胸部相比，两种组织中的铅含量更高，这可能表明该地区的海鸟通过其饮食和觅食区暴露。资源分配对于允许不同海鸟物种在共同的繁殖地中共存至关重要，在这些繁殖地中，它们充当中心觅食者。尽管如此，在环境污染的情况下，这些物种特异性策略导致差异的生物积累，因此，预计污染对人口的明显影响。
