University of Washington, Seattle, WA 98195, USA.
Proc Biol Sci. 2010 Jun 7;277(1688):1695-703. doi: 10.1098/rspb.2009.2342. Epub 2010 Feb 3.
Phenological dynamics are controlled by environmental factors, disturbance regimes and species interactions that alter growth or mortality risk. Ecosystem engineers can be a key source of disturbance, yet their effects on the phenologies of co-occurring organisms are virtually unexplored. We investigated how the abundance of a dominant ecosystem engineer, spawning sockeye salmon (Oncorhynchus nerka), alters the emergence phenology of stream insects. In streams with high densities of salmon, peak insect emergence occurred in early July, immediately prior to salmon spawning. By contrast, peak insect emergence in streams with low densities of salmon was weeks later and more protracted. The emergence of specific taxa was also significantly related to salmon density. A common rearing experiment revealed that differences in emergence timing are maintained in the absence of spawning salmon. We hypothesize that these patterns are probably driven by predictable and severe disturbance from nest-digging salmon driving local adaptation and being a trait filter of insect emergence. Thus, salmon regulate the timing and duration of aquatic insect emergence, a cross-ecosystem flux from streams to riparian systems.
物候动态受环境因素、干扰状态和物种相互作用的控制，这些因素会改变生长或死亡风险。生态系统工程师可能是干扰的一个关键来源，但它们对共存生物物候的影响实际上还没有被探索过。我们研究了占优势的生态系统工程师——产卵的红大麻哈鱼（Oncorhynchus nerka）的丰度如何改变溪流昆虫的出现物候。在鲑鱼密度高的溪流中，昆虫的高峰期出现在 7 月初，就在鲑鱼产卵之前。相比之下，鲑鱼密度低的溪流中昆虫的高峰期则晚了数周，而且持续时间更长。特定类别的昆虫的出现也与鲑鱼的密度有显著的关系。一项常见的饲养实验表明，在没有产卵鲑鱼的情况下，出现时间的差异得以维持。我们假设这些模式可能是由挖巢鲑鱼带来的可预测和严重的干扰驱动的，这是对昆虫出现的一种适应和特征筛选。因此，鲑鱼调节了水生昆虫出现的时间和持续时间，这是一个从溪流到河岸系统的跨生态系统通量。
