Nutrients and temperature interact to regulate algae and heterotrophic bacteria in an Alaskan poor fen peatland

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Wyatt, Kevin H., Bange, Jill S., Fitzgibbon, Andrea S., Bernot, Melody J., Rober, Allison R.
• Other Authors: Smith, Ralph
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2015
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; permafrost
• Online Access: http://dx.doi.org/10.1139/cjfas-2014-0425; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjfas-2014-0425; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjfas-2014-0425

Permafrost thaw associated with warmer temperatures is expected to elevate nutrient levels in northern aquatic ecosystems, including peatlands. To evaluate these effects on algae and heterotrophic bacteria, we manipulated nutrients (nitrogen (N) and phosphorus (P)) and temperature (ambient and warmed) in a factorial design using nutrient diffusing substrates inside warming chambers in an Alaskan peatland. After 16 days, there was no effect of warming on the abundance of algae or heterotrophic bacteria in the absence of nutrient enrichment. Algal production and bacterial biomass were substantially elevated by N with and without P (NP and N, respectively), independent of warming. Warming significantly enhanced the effect of nutrient enrichment on the abundance of algae and heterotrophic bacteria compared with ambient temperatures. Rates of N fixation increased with the presence of heterocyst-forming cyanobacteria, which represented a greater proportion of algal taxonomic composition in the absence of N enrichment in both ambient and warmed conditions. Our results indicate that warmer temperatures and nutrient enrichment will elevate algal and heterotrophic metabolism in northern peatlands, and the magnitude of increase will depend on the combination of nutrients available during periods of inundation.