Temperature and nutrient supply interact to control nitrogen fixation in oligotrophic streams: An experimental examination

Abstract

We performed two experiments to examine how temperature and nutrients interact to control dinitrogen (N 2 ) fixation, chlorophyll a (Chl a) biomass, and community composition of periphyton in subalpine oligotrophic streams in the Sawtooth Mountains of Idaho. We grew periphyton on nutrient-diffusing substrata (NDS) in a cold lake inlet (7uC) and a warm lake outlet (18uC). We then switched substrata between the two stream sites to test the effect of incubation temperature on N 2 -fixation rates. Periphyton on substrata grown at both sites exhibited greater N 2 -fixation rates when incubated in the warm outlet, which indicates physiologic temperature control. Periphyton on P-enriched NDS grown in the warm outlet had the greatest N 2 -fixation rates, largest Chl a biomass, and largest percentage of N 2 -fixing taxa of any treatment, which indicates that temperature and P interact to influence the community. In the second experiment, colonized rocks and uncolonized NDS were placed in cold (13uC) and warm (18uC) mesocosms. Within 2 days, warm temperature stimulated N 2 fixation by the rock periphyton community two times above cold temperatures, which indicates physiologic temperature control. After 45 days, warm temperatures and P enrichment led to Anabaena sp. in the periphyton community and the greatest rates of N 2 fixation observed in the experiment, which also indicates temperature and nutrient control at the community level. This study indicates that N 2 fixation and periphyton community composition in oligotrophic streams are controlled by both temperature and P supply, with temperature modulating the response to P.

Grazing minnows increase benthic autotrophy and enhance the response of periphyton elemental composition to experimental phosphorus additions

“…P enrichment also increased periphyton biomass (as chlorophyll a [CHLA]), but N enrichment had no effect on periphyton biomass. Therefore, the study by Marcarelli and Wurtsbaugh (2006) provided a good example of how N 2 fixation can supplement the N supply to periphyton communities that are strongly P limited. What remains unclear is how much N can be provided by N 2 fixation in streams experiencing stronger N limitation.…”

“…For instance, Grimm and Petrone (1997) demonstrated that fixed N 2 provided up to 85% of the net N flux into the benthos of a desert stream. Marcarelli and Wurtsbaugh (2006) recently showed that P and temperature interacted to control N 2 fixation in periphyton from oligotrophic streams. P enrichment increased periphyton N 2 fixation rates by increasing the density of N 2 -fixing organisms within the periphyton community.…”

“…NDS have been used in lakes (Fairchild and Lowe 1984, Pringle and Bowers 1984, Fairchild et al 1985, wetlands (Scott et al 2005), streams (Lowe et al 1986, Winterbourn and Fegley 1989, Tate 1990, Marcarelli and Wurtsbaugh 2006, Tank et al 2006, and large rivers (Corkum 1996, Scrimgeour andChambers 1997). Periphyton accumulates on diffusion surfaces when NDS are deployed in natural waters, and differences in accumulation rates between nutrient treatments and controls are interpreted as evidence of periphyton nutrient limitation.…”

Influence Mechanisms of Rainfall and Terrain Characteristics on Total Nitrogen Losses from Regosol

“…Furthermore, other soil components have effects of the background value of nitrogen; for instance, the content of clay particles in soil could affect the mass fraction of TN in soil [35]. Meanwhile, those impacts mainly related to temperature [36]. However, in this study, TN was taken as the pollutant, which included various forms of nitrogen; therefore, the impacts of the conversion among various forms of nitrogen on TN concentrations and TN loads could be ignored.…”

Nitrogen Fluxes Into, Out Of, and Within a Virginia Permaculture Livestock Farm

“…In aquatic systems, BNF is most commonly carried out by cyanobacteria, and is highly seasonally and spatially variable (Marcarelli andWurtsbaugh 2009, Patoine et al 2006). N fixation typically peaks in late summer when inflows are lowest, light availability is greatest and water temperature is highest (Marcarelli and Wursbaugh 2009 while short-term sinks include N burial in sediment, and N uptake by primary producers.…”