Didymosphenia geminata (Didymo) is an algal species native to North America, however overgrowth of Didymo has become problematic for many aquatic species as stalk formation has increased across North America in recent decades (Blanco & Ector, 2009) (Spaulding & Elwell, 2007). Didymo is a stalk producing species, interestingly, when overgrowth occurs cell division does not increase but rather decreases as stalk formation increases (Bothwell & Kilroy, 2014). Research suggests that overgrowth may be triggered by conditions of low phosphorus (Bothwell & Kilroy, 2014) and work by Ellwood and Whitton (2009) has shown that Didymo stalks produce alkaline phosphatase, an enzyme that has the ability to break down organic matter to release phosphorus.
Because glaciers provide abundant rock sources of P, we hypothesize that increased Didymo blooms in western North America may be related to declining glacier contributions to streamflow. To test this, we have measured Total Phosphorus and Soluble Reactive Phosphorus in streams across a gradient in glacier cover in northern U.S. and southeastern B.C. We also measured other water quality parameters, and, more importantly took periphyton samples to look for the presence of Didymo. To capture a comprehensive gradient in glaciation further sampling will be conducted. To further elucidate the conditions that facilitate stalk formation we plan to conduct flume experiments with controlled nutrient concentrations and turbidity conditions.