Yurkowski David J, Ferguson Steven H, Semeniuk Christina A D, Brown Tanya M, Muir Derek C G, Fisk Aaron T
Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, N9B 3P4, Canada.
Freshwater Institute, Fisheries and Oceans Canada, Winnipeg, MB, R3T 2N6, Canada.
Oecologia. 2016 Mar;180(3):631-44. doi: 10.1007/s00442-015-3384-5. Epub 2015 Jul 26.
Spatial and temporal variation can confound interpretations of relationships within and between species in terms of diet composition, niche size, and trophic position (TP). The cause of dietary variation within species is commonly an ontogenetic niche shift, which is a key dynamic influencing community structure. We quantified spatial and temporal variations in ringed seal (Pusa hispida) diet, niche size, and TP during ontogeny across the Arctic-a rapidly changing ecosystem. Stable carbon and nitrogen isotope analysis was performed on 558 liver and 630 muscle samples from ringed seals and on likely prey species from five locations ranging from the High to the Low Arctic. A modest ontogenetic diet shift occurred, with adult ringed seals consuming more forage fish (approximately 80 versus 60 %) and having a higher TP than subadults, which generally decreased with latitude. However, the degree of shift varied spatially, with adults in the High Arctic presenting a more restricted niche size and consuming more Arctic cod (Boreogadus saida) than subadults (87 versus 44 %) and adults at the lowest latitude (29 %). The TPs of adult and subadult ringed seals generally decreased with latitude (4.7-3.3), which was mainly driven by greater complexity in trophic structure within the zooplankton communities. Adult isotopic niche size increased over time, likely due to the recent circumpolar increases in subarctic forage fish distribution and abundance. Given the spatial and temporal variability in ringed seal foraging ecology, ringed seals exhibit dietary plasticity as a species, suggesting adaptability in terms of their diet to climate change.
空间和时间变化可能会混淆对物种内部和物种之间在饮食组成、生态位大小和营养级（TP）方面关系的解释。物种内部饮食变化的原因通常是个体发育生态位转移，这是影响群落结构的关键动态因素。我们量化了北极地区（一个快速变化的生态系统）环斑海豹（Pusa hispida）在个体发育过程中饮食、生态位大小和营养级的空间和时间变化。对来自环斑海豹的558份肝脏样本和630份肌肉样本以及来自北极高纬度到低纬度五个地点的可能猎物物种进行了稳定碳和氮同位素分析。环斑海豹在个体发育过程中发生了适度的饮食转变，成年环斑海豹消耗更多的饵料鱼（约80%对60%），并且营养级高于亚成体，营养级通常随纬度降低。然而，这种转变的程度在空间上有所不同，北极高纬度地区的成年环斑海豹生态位大小更受限，比亚成体（87%对44%）和最低纬度地区的成年环斑海豹（29%）消耗更多的北极鳕（Boreogadus saida）。成年和亚成年环斑海豹的营养级通常随纬度降低（4.7 - 3.3），这主要是由浮游动物群落中营养结构的更大复杂性驱动的。成年环斑海豹的同位素生态位大小随时间增加，这可能是由于近期北极亚寒带饵料鱼分布和丰度在环北极地区增加所致。鉴于环斑海豹觅食生态的空间和时间变异性，环斑海豹作为一个物种表现出饮食可塑性，表明其在饮食方面对气候变化具有适应性。
