Can uptake length in streams be determined by nutrient addition experiments? Results from an interbiome comparison study

Mulholland, Patrick J.; Tank, Jennifer L.; Webster, Jackson R.; Bowden, William B.; Dodds, Walter K.; Gregory, Stan V.; Grimm, Nancy B.; Hamilton, Stephen K.; Johnson, Sherri L.; Martı́, Eugènia; McDowell, William H.; Merriam, J. L.; Meyer, Judy L.; Peterson, Bruce J.; Valett, H. Maurice; Wollheim, W. M.

doi:10.2307/1468429

Cited by 191 publications

(213 citation statements)

References 37 publications

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“…By contrast, 4 months of stratification were required to deplete NO { 3 in the larger hypolimnion in Harsha Lake. Finally, NO { 3 concentration can directly control denitrification rates through enzyme kinetics (Mulholland et al 2002) and indirectly by partially controlling the mass of NO { 3 in the hypolimnion available for denitrifiers. Nitrate concentration at the onset of stratification in Harsha Lake was a factor of 4 greater than that reported by Grantz et al (2012), further contributing to the differences in denitrification rates between these studies.…”

Section: Discussionmentioning

confidence: 99%

“…The amount of N 2 O produced via denitrification is a function of the overall denitrification rate, which is often controlled by NO { 3 and oxygen concentrations (Mulholland et al 2008), and the proportion of the denitrified NO { 3 that is released as N 2 O rather than N 2 (i.e., the N 2 O yield). Denitrification occurs through the sequential reduction of NO { 3 to nitrite (NO { 2 ), nitric oxide (NO), N 2 O, and N 2 (Fig.…”

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confidence: 99%

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Denitrification alternates between a source and sink of nitrous oxide in the hypolimnion of a thermally stratified reservoir

Beaulieu

Smolenski

Nietch

et al. 2014

Limnology & Oceanography

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Nitrogen loading from developed watersheds to aquatic ecosystems can stimulate microbial denitrification, a process that reduces nitrate (NO { 3 ) to dinitrogen (N 2 ) or nitrous oxide (N 2 O), the latter a potent greenhouse gas. While aquatic ecosystems are a globally significant source of N 2 O to the atmosphere, the relationship between denitrification and N 2 O production is not well known. Until recently, this field of research has been limited by the technical challenges of simultaneously measuring denitrification and N 2 O production or consumption in situ at the ecosystem scale. Here we use membrane inlet mass spectrometry, an analytical method providing precise and accurate measurements of dissolved N 2 , and gas chromatography to directly measure N 2 and N 2 O concentrations in the hypolimnion of a stratified reservoir draining an agricultural watershed. Denitrification resulted in a consistent increase in dissolved N 2 and decrease in NO

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Denitrification alternates between a source and sink of nitrous oxide in the hypolimnion of a thermally stratified reservoir

Beaulieu

Smolenski

Nietch

et al. 2014

Limnology & Oceanography

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“…For each date, we estimated an upper and lower limit of U gross based on the previously calculated 95% confidence interval (CI) of k gross . Measurements of k gross and U gross can be underestimated during solute-addition experiments because of nutrient enrichment effects (Mulholland et al 2002). To minimize this effect, we adjusted the nutrient concentration of the added solution and the pump flow rate for each addition to reach a relatively low and similar nutrient-enrichment level among addition dates and streams.…”

Section: Calculation Of In-stream Processing Fluxesmentioning

confidence: 99%

A round-trip ticket: the importance of release processes for in-stream nutrient spiraling

Schiller¹,

Bernal²,

Sabater³

et al. 2015

Freshwater Science

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Most nutrient-spiraling studies have focused on estimates of gross uptake (U gross ), which show that streams take up dissolved inorganic nutrients very efficiently. However, studies based on estimates of net uptake (U net ) emphasize that streams tend to be at biogeochemical steady state (i.e., U net ≈ 0), at least on a time scale of hours. These findings suggest that streams can be highly reactive ecosystems but remain at short-term biogeochemical steady state if U gross is counterbalanced by release (R), a process that remains widely unexplored. Here, we propose a novel approach to infer R by comparing U net and U gross estimated from ambient and plateau concentrations obtained from standard short-term nutrient additions along a reach. We used this approach to examine the temporal variation of R and its balance with U gross in 2 streams with contrasting hydrological regime (i.e., perennial vs intermittent) during 2 years. We focused on the spiraling metrics of NH 4 + and soluble reactive P (SRP), essential sources of N and P in stream ecosystems. R differed substantially between the 2 streams. The perennial stream had a higher proportion of dates with R > 0 and a 2× higher mean R than the intermittent stream for both nutrients. Despite these differences, the magnitude of R and U gross tended to be similar for both nutrients within each stream, which lead to U net ≈ 0 in most cases. A notable exception occurred for SRP in the intermittent stream, where R tended to be higher than U gross during most of the winter period, probably because of desorption of P from stream sediments. Together, our findings shed light on the contribution of release processes to the dynamics of nutrient spiraling and support the idea that streams can be active ecosystems with high spiraling fluxes while simultaneously approaching short-term biogeochemical steady-state.

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“…to calculate the specific rate for an NH 4 þ uptake with increased concentrations (Mulholland et al 2002). We collected water samples before and during nutrient additions at eight stations along 1.4 km of Clear Creek to estimate uptake.…”

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confidence: 99%

Introduced lake trout alter nitrogen cycling beyond Yellowstone Lake

2015

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Citation: Tronstad, L. M., R. O. Hall Jr., and T. M. Koel. 2015. Introduced lake trout alter nitrogen cycling beyond Yellowstone Lake. Ecosphere 6(11):224. http://dx.doi.org/10.1890/ES14-00544.1Abstract. Introduced predators can have large effects on the ecosystem in which they were introduced, but how much these effects extend to other ecosystems beyond the invaded one is less known. We compared how lake trout (Salvelinus namaycush) affected nutrient cycling in an invaded and adjacent ecosystem in Yellowstone National Park, Wyoming, USA. Introduced lake trout in Yellowstone Lake caused the native Yellowstone cutthroat trout (Oncoryhynchus clarkii bouvieri ) population to decline. Native cutthroat trout are a dominant animal in the lake and may alter nutrient cycling in both Yellowstone Lake where they reside and in tributary streams used for spawning. We estimated changes in nutrient transport and nutrient uptake in both Yellowstone Lake and Clear Creek, a spawning stream, before and after the invasion of lake trout. Annual area-specific excretion fluxes from cutthroat trout were nine times higher in Clear Creek compared to Yellowstone Lake when cutthroat trout were abundant. However, fluxes within the lake and stream were similar after cutthroat trout declined. In Yellowstone Lake, zooplankton excretion supplied 86% of ammonium (NH 4 þ ) that was taken up, but cutthroat trout only supplied ,0.3% after the introduction of lake trout. Conversely, NH 4 þ excreted by cutthroat trout was likely a major flux in ClearCreek, because NH 4 þ fluxes from cutthroat trout exceeded watershed export of NH 4 þ in years when .3000 cutthroat trout spawned. Furthermore, NH 4 þ excretion fluxes from spawning cutthroat trout in ClearCreek supplied up to 6.1% of the NH 4 þ demanded by microbes after the introduction of lake trout.However, based on modeled past NH 4 þ uptake, we estimated that up to 60% of NH 4 þ excreted by spawning cutthroat trout may have been taken up by stream microbes when cutthroat trout were abundant. Therefore, transported NH 4 þ from spawning cutthroat trout was likely an integral part of N cycling in tributary streams in the past. By comparing the effects of declining cutthroat trout on two ecosystems, we show that lake trout had a larger effect on N cycling within an adjacent stream ecosystem than the invaded lake ecosystem itself, because the migratory behavior of cutthroat trout concentrated them in spawning streams increasing their effect.

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Can uptake length in streams be determined by nutrient addition experiments? Results from an interbiome comparison study

Cited by 191 publications

References 37 publications

Denitrification alternates between a source and sink of nitrous oxide in the hypolimnion of a thermally stratified reservoir

Denitrification alternates between a source and sink of nitrous oxide in the hypolimnion of a thermally stratified reservoir

A round-trip ticket: the importance of release processes for in-stream nutrient spiraling

Introduced lake trout alter nitrogen cycling beyond Yellowstone Lake

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