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| Titel |
UV effects on the primary productivity of picophytoplankton: biological weighting functions and exposure response curves of Synechococcus |
| VerfasserIn |
P. J. Neale, A. L. Pritchard, R. Ihnacik |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 10 ; Nr. 11, no. 10 (2014-05-28), S.2883-2895 |
| Datensatznummer |
250117429
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| Publikation (Nr.) |
 copernicus.org/bg-11-2883-2014.pdf |
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| Zusammenfassung |
| A model that predicts UV effects on marine primary productivity using a
biological weighting function (BWF) coupled to the photosynthesis–irradiance
response (BWF/P-E model) has been implemented for two strains of the
picoplanktonic cyanobacteria Synechococcus, WH7803 and WH8102,
which were grown at two irradiances (77 and
174 μmol m−2 s−1 photosynthetically available radiation (PAR)) and two temperatures (20 and
26 °C). The model was fit using photosynthesis measured in a
polychromatic incubator with 12 long-pass filter configurations with 50%
wavelength cutoffs ranging from 291 to 408 nm, giving an effective
wavelength range of 280–400 nm. Examination of photosynthetic response vs.
weighted exposure revealed that repair rate progressively increases at low
exposure but reaches a maximum rate above a threshold exposure
("Emax"). Adding Emax as a parameter to the BWF/P-E model
provided a significantly better fit to Synechococcus data than the
existing "E" or "T" models. Sensitivity to UV inhibition varied with
growth conditions for both strains, but this was mediated mainly by
variations in Emax for WH8102 while both the BWF and Emax changed
for WH7803. Higher growth temperature was associated with a considerable
reduction in sensitivity, consistent with an important role of repair in
regulating sensitivity to UV. Based on nominal water column conditions (noon,
solstice, 23° latitude, "blue" water), the BWFEmax/P-E
model estimates that UV + PAR exposure inhibits Synechococcus
photosynthesis from 78 to 91% at 1 m, and integrated productivity to
150 m 17–29% relative to predicted rates in the absence of inhibition. |
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