| Title | Quantifying the response of phytoplankton photosynthesis to ultraviolet radiation: Biological weighting functions versus in situ measurements in two Swiss lakes |
| Abstract | The sensitivity of photosynthesis to ultraviolet radiation (UV) was assessed for phytoplankton assemblages in two Swiss lakes, pre-alpine Lake Lucerne (Vierwaldstättersee) and alpine Lake Cadagno, using both in situ and laboratory incubations. Biological weighting functions for UV inhibition of photosynthesis (BWFs) were determined in the laboratory using polychromatic exposures in a Xe-lamp based incubator. Samples were concurrently incubated in situ under UV exposed and protected bottles (profiles 05 m), while additional spectral treatments were carried out at the 50% UV-B penetration depth: full spectrum, UV-A only (Mylar protected) and UV protected quartz tubes. Both particulate (> 0.2 mm) and total organic carbon incorporation were measured. Measured attenuation coefficients and incident UV spectral irradiance data was used to evaluate a BWF/photosynthesis-irradiance model (BWF/P-I) for in situ exposure conditions and compared with measurements. The BWFs showed sensitivity across the UV spectrum at similar, though somewhat lower, levels than an average BWF for marine assemblages. Relative photosynthesis in situ (UV exposed/UV excluded) was about 40% at the surface and about 60% at the 50% UV-B penetration depth. Similar inhibition was predicted by the BWF/P-I model. Generally, full spectrum (UV-B and UV-A) exposure had little additional effect compared to UV-A only exposure. Reciprocal transfer of samples between lakes showed enhancement of UV effects in L. Cadagno compared to incubation of the same sample in L. Lucerne, consistent with increased UV sensitivity due to the 5°C cooler water temperature in L. Cadagno. Similarly, BWF prediction of in situ response in L. Cadagno was improved by increasing UV sensitivity according to a Q10 of 2. |
| Source | Aquatic sciences (Print. ed.) 63, pp. 265–285 |
| Keywords | Ambienti lacustriProduzione primariaInibizione da UV |
| Journal | Aquatic sciences (Print. ed.) |
| Editor | Birkhäuser, Basel, Svizzera |
| Year | 2001 |
| Type | Articolo in rivista |
| Authors | Neale P.J. 1, Litchman E. 2, Sobrino C. 3, Callieri C. 4, Morabito G. 4, Montecino V. 5, Hout Y. 6, Bossard P. 2, Lehmann C. 2, Steiner D. 7 |
| Text | 52791 2001 Ambienti lacustri Produzione primaria Inibizione da UV Quantifying the response of phytoplankton photosynthesis to ultraviolet radiation Biological weighting functions versus in situ measurements in two Swiss lakes Neale P.J. 1, Litchman E. 2, Sobrino C. 3, Callieri C. 4, Morabito G. 4, Montecino V. 5, Hout Y. 6, Bossard P. 2, Lehmann C. 2, Steiner D. 7 1 Smithsonian Environmental Research Center USA, 2 EAWAG Svizzera, 3 C.S.I.C Spagna, 4 CNR ISE, 5 Universidad de Chile, 6 Dalhousie University Halifax Canada, 7 University of Zurich The sensitivity of photosynthesis to ultraviolet radiation UV was assessed for phytoplankton assemblages in two Swiss lakes, pre alpine Lake Lucerne Vierwaldstattersee and alpine Lake Cadagno, using both in situ and laboratory incubations. Biological weighting functions for UV inhibition of photosynthesis BWFs were determined in the laboratory using polychromatic exposures in a Xe lamp based incubator. Samples were concurrently incubated in situ under UV exposed and protected bottles profiles 05 m , while additional spectral treatments were carried out at the 50% UV B penetration depth full spectrum, UV A only Mylar protected and UV protected quartz tubes. Both particulate > 0.2 mm and total organic carbon incorporation were measured. Measured attenuation coefficients and incident UV spectral irradiance data was used to evaluate a BWF/photosynthesis irradiance model BWF/P I for in situ exposure conditions and compared with measurements. The BWFs showed sensitivity across the UV spectrum at similar, though somewhat lower, levels than an average BWF for marine assemblages. Relative photosynthesis in situ UV exposed/UV excluded was about 40% at the surface and about 60% at the 50% UV B penetration depth. Similar inhibition was predicted by the BWF/P I model. Generally, full spectrum UV B and UV A exposure had little additional effect compared to UV A only exposure. Reciprocal transfer of samples between lakes showed enhancement of UV effects in L. Cadagno compared to incubation of the same sample in L. Lucerne, consistent with increased UV sensitivity due to the 5°C cooler water temperature in L. Cadagno. Similarly, BWF prediction of in situ response in L. Cadagno was improved by increasing UV sensitivity according to a Q10 of 2. 63 Published version La validita dei risultati sperimentali ottenuti risiede, in particolare, nellavere avuto la possibilita di condurre, in contemporanea, le misure in ambienti differenti ed in laboratorio, condizioni molto difficile da ottenere nella maggior parte degli studi di questo tipo. Fattore dimpatto 0,857. Articolo in rivista Birkhauser 1015 1621 Aquatic sciences Print. ed. Aquatic sciences Print. ed. Aquat. sci. Print. ed. Aquatic sciences. Print. ed. cristiana.callieri CALLIERI CRISTIANA giuseppe.morabito MORABITO GIUSEPPE |
