Abstract
| Originalsprog | Engelsk |
|---|---|
| Tidsskrift | Limnology and Oceanography |
| Vol/bind | 52 |
| Udgave nummer | 1 |
| Sider (fra-til) | 108–120 |
| ISSN | 0024-3590 |
| Status | Udgivet - 2007 |
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- Temporal dynamics and regulation of lake metabolismForlagets udgivne version, 849 KB
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Temporal dynamics and regulation of lake metabolism. / Stæhr, Peter Anton; Jensen, Kaj Sand.
I: Limnology and Oceanography, Bind 52, Nr. 1, 2007, s. 108–120.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review
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TY - JOUR
T1 - Temporal dynamics and regulation of lake metabolism
AU - Stæhr, Peter Anton
AU - Jensen, Kaj Sand
PY - 2007
Y1 - 2007
N2 - We studied temporal dynamics and regulation of oxygen metabolism in the upper mixed layer of a nutrientrichshallow Danish lake by continuous measurements of oxygen, irradiance, wind, and temperature and frequentmeasurements of algal chlorophyll, organic pools, and inorganic nutrients. Chlorophyll, algal growth rate, andmean irradiance (Emean) in the mixed surface layer were calculated daily from continuous measurements ofirradiance and temperature with depth. There were three to four distinct maxima in gross primary production(GPP) and community respiration (R) during the summer season and minima from fall to spring after broad-scalechanges in irradiance, temperature, mixing depth, and biomass and growth rate of the algal community andconcentrations of inorganic nutrients. Lake metabolism was annually balanced (mean GPP :R 1.04 in 2003 and1.01 in 2004), with net autotrophy occurring mainly from mid-May to mid-September (mean GPP:R 1.14 in 2003and 1.10 in 2004), and net heterotrophy outside this period (mean GPP:R 0.60 in 2003 and 0.81 in 2004).However, GPP :R varied two- to threefold from day to day because lower surface irradiance, higher mixingdepth, and thus lower Emean significantly reduced GPP. Normalizing GPP to chlorophyll provided an index ofalgal growth potential (GPPB), which followed a hyperbolic relationship to Emean, and both parameters wererelated to blooms and collapses of algal biomass. Metabolic rates were much more variable from day to day thanalgal biomass, which integrates growth and loss processes over longer periods. The continuous approach to lakemetabolism provides better data and can provide a more accurate picture than averages of a few discretemeasurements. Weekly averages reflected the characteristic seasonal peaks and troughs also observed for algalbiomass, whereas monthly averages did not. Daily measurements of lake metabolism, therefore, can provide theoptimal background for evaluating temporal changes and regulation of algal biomass and organic pools innutrient-rich shallow lakes.
AB - We studied temporal dynamics and regulation of oxygen metabolism in the upper mixed layer of a nutrientrichshallow Danish lake by continuous measurements of oxygen, irradiance, wind, and temperature and frequentmeasurements of algal chlorophyll, organic pools, and inorganic nutrients. Chlorophyll, algal growth rate, andmean irradiance (Emean) in the mixed surface layer were calculated daily from continuous measurements ofirradiance and temperature with depth. There were three to four distinct maxima in gross primary production(GPP) and community respiration (R) during the summer season and minima from fall to spring after broad-scalechanges in irradiance, temperature, mixing depth, and biomass and growth rate of the algal community andconcentrations of inorganic nutrients. Lake metabolism was annually balanced (mean GPP :R 1.04 in 2003 and1.01 in 2004), with net autotrophy occurring mainly from mid-May to mid-September (mean GPP:R 1.14 in 2003and 1.10 in 2004), and net heterotrophy outside this period (mean GPP:R 0.60 in 2003 and 0.81 in 2004).However, GPP :R varied two- to threefold from day to day because lower surface irradiance, higher mixingdepth, and thus lower Emean significantly reduced GPP. Normalizing GPP to chlorophyll provided an index ofalgal growth potential (GPPB), which followed a hyperbolic relationship to Emean, and both parameters wererelated to blooms and collapses of algal biomass. Metabolic rates were much more variable from day to day thanalgal biomass, which integrates growth and loss processes over longer periods. The continuous approach to lakemetabolism provides better data and can provide a more accurate picture than averages of a few discretemeasurements. Weekly averages reflected the characteristic seasonal peaks and troughs also observed for algalbiomass, whereas monthly averages did not. Daily measurements of lake metabolism, therefore, can provide theoptimal background for evaluating temporal changes and regulation of algal biomass and organic pools innutrient-rich shallow lakes.
M3 - Journal article
VL - 52
SP - 108
EP - 120
JO - Limnology and Oceanography
JF - Limnology and Oceanography
SN - 0024-3590
IS - 1
ER -