Decadal Shifts Towards Higher Riverine Silicon Relative to Nitrogen and Phosphorus Across High Latitudes
Journal Article
Overview
abstract
Abstract; High‐latitude systems are warming faster than the global average, altering the rates of silicon (Si) mobilization from terrestrial to aquatic systems. Dissolved Si (DSi) concentration and its ratio with other nutrients exert strong controls on algae blooms in fresh and marine receiving waters, especially in high‐latitude regions where diatoms often dominate riverine and coastal autotroph communities. Here we present an examination of decadal scale changes in river DSi concentrations, loads, and nutrient ratios in 70 high‐latitude rivers (>58°) across North America, Europe, Asia, and Antarctica. We examined monthly and annual changes in DSi, dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphorus (DIP) concentrations and yields using sequential breakpoint analysis (i.e., SiZer) that allows for variable trend identification within a single time series. Except for the Antarctic streams, we found a predominant trend of increasing DSi relative to DIN and DIP for both annual concentrations and yields, driven primarily by declines in DIN and DIP rather than increases in DSi. Contrary to expectations, we found little evidence that changes in discharge or shifts in seasonality (i.e., month‐specific trends) drove these altered interannual nutrient dynamics. However, interannual changes in DSi concentrations were associated with hydroclimatic variability (precipitation, evapotranspiration, snow cover, air temperature) and DIP availability. Taken together, our analysis identifies large‐scale shifts in exports of Si, N, and P in high‐latitude rivers, with implications for algae productivity and composition in the highly productive waters of high‐latitude ecosystems.
