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

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 warme...

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Published inCanadian journal of fisheries and aquatic sciences Vol. 72; no. 3; pp. 447 - 453
Main Authors Wyatt, Kevin H, Bange, Jill S, Fitzgibbon, Andrea S, Bernot, Melody J, Rober, Allison R
Format Journal Article
LanguageEnglish
Published Ottawa NRC Research Press 01.03.2015
Canadian Science Publishing NRC Research Press
Subjects
Algae
Aquatic ecosystems
Bacteria
Cyanobacteria
Environmental aspects
Gram-negative bacteria
Heterotrophs
Nutrients
Nutritional aspects
Peat
Peatlands
Permafrost
Temperature
United States
Alaska
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Summary: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.
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ISSN:0706-652X
1205-7533
DOI:10.1139/cjfas-2014-0425