The introduction of salmonids into lakes of western North America for sport fishing is a widespread phenomenon. While numerous investigations have documented cascading trophic interactions upon the introduction of fish into naturally fishless systems, little research has been done to investigate the importance of natural fish status (fishless vs. fish bearing) in modulating historical food web response to dual forcing by bottom-up (resource regulation from nutrients) and top-down (planktivory from stocked fish) processes. We used the paleolimnological record to reconstruct food web changes in four lakes in interior British Columbia that have been stocked with rainbow trout since the early to mid-1900s. Analysis of pigments, diatoms, and Cladocera was undertaken in cores from all lakes. We predicted that if fish were important in structuring cladoceran abundance and composition, we would document a decline in the abundance of large daphnids post-stocking in our two naturally fishless lakes, and little change in the two fish-bearing lakes. Instead, we documented increased abundance of large daphnids after stocking in all lakes in the early to mid-1900s, a finding inconsistent with size-selective predation from planktivorous fish. Further, our data suggest that deep, low-oxygen refugia may be important in sustaining populations of large Daphnia, a process which was enhanced by increased nutrients and lake production according to sub-fossil diatom and pigment analyses. This study shows that fish stocking does not invariably result in a decrease in large-bodied Cladocera and that nutrients and lake type can modulate the response of invertebrate planktivores.

将鲑鱼引入北美西部的湖泊中进行运动钓鱼是一种普遍现象。尽管大量研究记录了将鱼引入天然无鱼系统后的级联营养相互作用，但很少进行研究来研究天然鱼的状况（无鱼vs.含鱼）在调节历史食物网对海底双重强迫的反应中的重要性。上（从养分中进行资源调节）和自上而下（从放养鱼类中捕捞）过程。自1900年代初至中期以来，我们利用古脂学记录重建了不列颠哥伦比亚省内陆的四个湖泊中食物网的变化，该湖中养有虹鳟鱼。在所有湖泊的岩心中进行了色素，硅藻和角藻的分析。我们预测，如果鱼类在构建枝角类鱼类的丰度和组成方面很重要，那么我们将证明我们两个自然无鱼的湖泊中放养大型大型水蚤的数量减少，而这两个有鱼的湖泊变化不大。取而代之的是，我们记录了在1900年代初至中期在所有湖泊中放养后大型水蚤的数量增加，这一发现与浮游鱼类的选择性捕食不一致。此外，我们的数据表明，深层的低氧避难所可能对维持大量人 我们记录了在1900年代初至中期在所有湖泊中放养后大型水蚤的数量增加，这一发现与浮游鱼类的尺寸选择性捕食不一致。此外，我们的数据表明，深层的低氧避难所可能对维持大量人 我们记录了在1900年代初至中期在所有湖泊中放养后大型水蚤的数量增加，这一发现与浮游鱼类的尺寸选择性捕食不一致。此外，我们的数据表明，深层的低氧避难所可能对维持大量人水蚤，根据亚化石硅藻和色素分析，通过增加养分和增加湖泊产量来增强水蚤的过程。这项研究表明，鱼类的放养不会总是导致大型克拉德克拉多藻的减少，养分和湖泊类型可以调节无脊椎动物浮游动物的反应。