Ecosystem metabolism in a stratified lake
Research output: Contribution to journal › Journal article › Research › peer-review
Standard
Ecosystem metabolism in a stratified lake. / Stæhr, Peter Anton; Christensen, Jesper Philip Aagaard; Batt, Ryan D.; Read, Jordan S.
In: Limnology and Oceanography, Vol. 57, No. 5, 2012, p. 1317-1330.Research output: Contribution to journal › Journal article › Research › peer-review
Harvard
APA
Vancouver
Author
Bibtex
}
RIS
TY - JOUR
T1 - Ecosystem metabolism in a stratified lake
AU - Stæhr, Peter Anton
AU - Christensen, Jesper Philip Aagaard
AU - Batt, Ryan D.
AU - Read, Jordan S.
PY - 2012
Y1 - 2012
N2 - Seasonal changes in rates of gross primary production (GPP), net ecosystem production (NEP), and respiration (R) were determined from frequent automated profiles of dissolved oxygen (DO) and temperature in a clear-water polymictic lake. Metabolic rate calculations were made using a method that integrates rates across the entire depth profile and includes DO exchange between depth layers driven by mixed-layer deepening and eddy diffusivity. During full mixing, NEP was close to zero throughout the water column, and GPP and R were reduced 2-10 times compared to stratified periods. When present, the metalimnion contributed 21% and 27% to whole-lake areal rates of GPP and R, respectively. Net autotrophy prevailed in the epilimnion (NEP = 11 +/- 14 mmol O-2 m(-3) d(-1); mean 6 +/- SD) compared to balanced production in the metalimnion (NEP = 2 +/- 19 mmol O-2 m(-3) d(-1)) and net heterotrophic conditions in hypolimnic waters (NEP = -15 +/- 24 mmol O-2 m(-3) d(-1)). Positive NEP occurred in the metalimnion during periods when the photic depth extended below the mixed-layer depth. Although the single-sonde method estimated higher areal GPP (19%) and R (14%) compared to the two depth-integrated approaches, differences were not significant. During stratification, daily variability in epilimnetic DO was dominated by metabolism (46%) and air-water gas exchange (44%). Fluxes related to mixed-layer deepening dominated in meta- and hypolimnic waters (49% and 64%), while eddy diffusion (1% and 14%) was less important. Although air-water gas exchange rates differed among the three formulations of gas-transfer velocity, this had no significant effect on metabolic rates.
AB - Seasonal changes in rates of gross primary production (GPP), net ecosystem production (NEP), and respiration (R) were determined from frequent automated profiles of dissolved oxygen (DO) and temperature in a clear-water polymictic lake. Metabolic rate calculations were made using a method that integrates rates across the entire depth profile and includes DO exchange between depth layers driven by mixed-layer deepening and eddy diffusivity. During full mixing, NEP was close to zero throughout the water column, and GPP and R were reduced 2-10 times compared to stratified periods. When present, the metalimnion contributed 21% and 27% to whole-lake areal rates of GPP and R, respectively. Net autotrophy prevailed in the epilimnion (NEP = 11 +/- 14 mmol O-2 m(-3) d(-1); mean 6 +/- SD) compared to balanced production in the metalimnion (NEP = 2 +/- 19 mmol O-2 m(-3) d(-1)) and net heterotrophic conditions in hypolimnic waters (NEP = -15 +/- 24 mmol O-2 m(-3) d(-1)). Positive NEP occurred in the metalimnion during periods when the photic depth extended below the mixed-layer depth. Although the single-sonde method estimated higher areal GPP (19%) and R (14%) compared to the two depth-integrated approaches, differences were not significant. During stratification, daily variability in epilimnetic DO was dominated by metabolism (46%) and air-water gas exchange (44%). Fluxes related to mixed-layer deepening dominated in meta- and hypolimnic waters (49% and 64%), while eddy diffusion (1% and 14%) was less important. Although air-water gas exchange rates differed among the three formulations of gas-transfer velocity, this had no significant effect on metabolic rates.
U2 - 10.4319/lo.2012.57.5.1317
DO - 10.4319/lo.2012.57.5.1317
M3 - Journal article
VL - 57
SP - 1317
EP - 1330
JO - Limnology and Oceanography
JF - Limnology and Oceanography
SN - 0024-3590
IS - 5
ER -
ID: 41887838