EFFECTS OF EARLY SNOWMELT PHENOLOGY ON HEADWATER STREAM BIOGEOCHEMISTRY
I have been working in streams near the Rocky Mountain Biological Laboratory since I began my doctoral studies at NCSU. The objective of my stream research program is to understand how climate induced changes in the phenology of seasonal transitions could affect stream ecosystem structure and function. Understanding phenological changes is pressing because shifts in the seasonal phenologies of both aquatic and terrestrial processes will accompany and could compound other ecological impacts of climate warming on stream ecosystems. In mountainous regions, recent studies show shifts towards earlier spring snowmelt and associated runoff, causing river flows to peak earlier and consequently reducing late season flow. Flow is a fundamental driver of water quality, energy and material transport, physical habitat, life history evolution, productivity, and biotic interactions in rivers; thus, changes in flow or its timing can transform a river’s structure and function.
High-discharge disturbance does not alter the seasonal trajectory of nutrient uptake in a montane streamBalik, J. A., West, D. C., & Taylor, B. W. (2021). High-discharge disturbance does not alter the seasonal trajectory of nutrient uptake in a montane stream. Hydrobiologia, 848(19), 4535-4550. (DOI, PDF) Here, we document the effects of a large midsummer flood event on the seasonal trajectory of reach-scale nitrogen and phosphorus uptake in the East River, a high elevation oligotrophic stream in central Colorado near the RMBL. Classic stream disturbance literature predicts that reach-scale nutrient demand should increase as benthic biofilms recover from the bed scour that occurs during floods. However, these classic studies are based on streams that flood frequently and are highly adapted to disturbance. In contrast, the East River experiences spring snowmelt peak flows followed by typically stable summertime base flows. We found that biofilm biomass accrued and areal P uptake increased after the midsummer flood. Whereas, during the same seasonal timeframe in a reference year without any midsummer floods, biofilm biomass and P uptake declined. N uptake did not change in either year. A higher proportion of algae in benthic biofilms was associated with greater uptake of both nutrients, suggesting that algae drive uptake. Thus, in a stream that infrequently receives floods during the growing season, algal biofilm accrual following a midsummer flood is a significant predictor of nutrient processing rates. |
An experimental test of climate-driven changes in stream temperature, light, and nutrient availability on biofilms and nutrient dynamicsThis work is currently undergoing peer review, but check back soon for an update! |