RESULTS
The long-term enrichment of the Kuparuk River led to major shifts in
primary producer species and production. After ten years of
P-enrichment, the epilithic diatom dominated system was replaced by
bryophytes, primarily Hygrohypnum spp., which led to a
restructuring of the macroinvertebrate community but only subtle impacts
on YOY and adult Arctic Grayling growth rates (Slavik et al., 2004).
Long-term monitoring of the Reference reach has revealed significant
increases in flow-weighted mean concentrations of nitrate and
significant decreases in flow-weighted mean concentrations of dissolved
organic N and P (DON and DOP) over time (Fig. 2). These trends were
noted recently by Kendrick et al. (2018) based on a shorter subset of
the Kuparuk River record. Updated results from the entire
~40-season Upper Kuparuk River experiment are summarized
in Iannucci, Beneš, Medvedeff, & Bowden (In review) in this issue.