Data from: Damming, lost connectivity and the historical role of anadromous fish in freshwater ecosystem dynamics

Recent research has demonstrated the important role that high-biomass species play in the transfer of energy and nutrients across habitat boundaries, as well as the ecosystem consequences of their loss. To contrast the historical and current biomass of historically abundant anadromous forage fish, we combined historical records of habitat loss from damming with contemporary freshwater productivity of alewives and diet data of freshwater predator fish. Significant declines in production occurred by 1850 in the northeastern United States, long before any direct abundance data were available, which would have had significant effects on freshwater prey resources for the numerous predators directly affected by the transfer of nutrients across the freshwater–marine nexus. Current freshwater systems operate at approximately 6.7% of historical capacity of anadromous alewife biomass and abundance. This provides an example of habitat-mediated changes in connectivity limiting nutrient flux and energy flow among populations and species that alter ecosystem function at multiple scales.近期研究已证实，高生物量物种在跨生境边界的能量与养分迁移过程中发挥着关键作用，同时明确了其种群消失对生态系统造成的连锁影响。为对比历史上种群繁盛的溯河洄游饵料鱼（anadromous forage fish）的历史与当前生物量，本研究将大坝建设导致的生境丧失历史记录，与当前西鲱（alewives）的淡水生产力数据以及淡水捕食性鱼类的食性数据进行了整合。早在直接丰度数据可被获取的数十年前，美国东北部的种群产量已于1850年出现显著下滑，这一变化对大量依托淡水-海洋养分连通通路获取营养的捕食者的淡水猎物资源造成了重大影响。当前淡水生态系统中的溯河洄游西鲱生物量与丰度仅约为历史水平的6.7%。本研究案例揭示了生境介导的连通性变化如何限制种群与物种间的养分通量与能量流动，进而在多尺度上改变生态系统功能。