| Title | Lake Maggiore (N. Italy) trophic history: fossil diatom, plant pigments, chironomids and comparison with long-term limnological data |
| Abstract | The availability of long-term series of chemical and biological data and the eutrophication/oligotrophication history of Lake Maggiore allows an attempt to correlate the registered changes with sedimentary records in several sediment cores. Documentary and palaeolimnological data were used to calibrate two important suites of sedimentary indicators of phytoplankton, diatoms and algal pigments.
Diatom assemblages in the sediment cores precisely reflect the pelagic diatom development for approximately the last century. Prediction of total algal biomass from the profile of the ubiquitous â-carotene and some algal groups in certain period of lake development (e.g. diatoms, Cryptophyta, cyanobacteria) was good, whereas the comparison of taxa-specific carotenoids and algal biomass standing stocks (as cell biovolume) in some case revealed poor correspondence. Selective carotenoid losses, taxa production, and mechanisms controlling pigment sedimentation are factors that biased the comparison. However, pigment concentrations and algal biovolumes are different units but equally valid. The use of fossil pigments complements other studies and provides more detailed information on algal development. A sub-fossil chironomid profile agrees well with the general trophic reconstruction as inferred from the pigment and diatom data, adding more details on changes in littoral substratum, water-level fluctuation and flood events.
Models to infer primary productivity and total phosphorus concentration in lake water from sedimentary pigments and diatom assemblages are tested: in the case of the TP reconstruction, reliable results were obtained in this case for the period of high trophic state and for the last decade. During the recovery phase of the 1980s, unexpected high abundance of Stephanodiscus minutulus leads to strong overestimation of TP concentrations. Similarly, the reconstructed primary productivity only disagrees with the experimental data for some years in the last decade. Sensitivity of the sedimentary pigment model as well as the relatively reduced sampling dates likely explains this discrepancy.
Similarities are also evident in the temporal diatom assemblage variations of an additional three sub-alpine Italian lakes. As well, the palaeolimnological reconstruction for Lake Maggiore parallels that for Lake Constance, another large sub-alphine lake located north of the Alps. |
| Source | Quaternary international 113, pp. 97–110 |
| Keywords | Lago Maggiore;phytoplankton;diatoms;algal pigments;sedimentary records |
| Journal | Quaternary international |
| Editor | Pergamon., Oxford, Regno Unito |
| Year | 2004 |
| Type | Articolo in rivista |
| DOI | 10.1016/S1040-6182(03)00082-X |
| Authors | Marchetto A., Lami A., Musazzi S., Masaferro J., Langone L., Guilizzoni P. |
| Text | 169265 2004 10.1016/S1040 6182 03 00082 X ISI Web of Science WOS 000186908600007 Lago Maggiore; phytoplankton; diatoms; algal pigments; sedimentary records Lake Maggiore N. Italy trophic history fossil diatom, plant pigments, chironomids and comparison with long term limnological data Marchetto A., Lami A., Musazzi S., Masaferro J., Langone L., Guilizzoni P. a CNR Istituto per lo Studio degli Ecosistemi, Sezione di Idrobiologia ed Ecologia delle Acque Interne, Largo V. Tonolli 50, 28922, Verbania Pallanza, Italy b CONICET, Bariloche, Argentina c CNR Istituto per la Geologia Marina, Via Gobetti 101, 40129, Bologna, Italy The availability of long term series of chemical and biological data and the eutrophication/oligotrophication history of Lake Maggiore allows an attempt to correlate the registered changes with sedimentary records in several sediment cores. Documentary and palaeolimnological data were used to calibrate two important suites of sedimentary indicators of phytoplankton, diatoms and algal pigments. Diatom assemblages in the sediment cores precisely reflect the pelagic diatom development for approximately the last century. Prediction of total algal biomass from the profile of the ubiquitous a carotene and some algal groups in certain period of lake development e.g. diatoms, Cryptophyta, cyanobacteria was good, whereas the comparison of taxa specific carotenoids and algal biomass standing stocks as cell biovolume in some case revealed poor correspondence. Selective carotenoid losses, taxa production, and mechanisms controlling pigment sedimentation are factors that biased the comparison. However, pigment concentrations and algal biovolumes are different units but equally valid. The use of fossil pigments complements other studies and provides more detailed information on algal development. A sub fossil chironomid profile agrees well with the general trophic reconstruction as inferred from the pigment and diatom data, adding more details on changes in littoral substratum, water level fluctuation and flood events. Models to infer primary productivity and total phosphorus concentration in lake water from sedimentary pigments and diatom assemblages are tested in the case of the TP reconstruction, reliable results were obtained in this case for the period of high trophic state and for the last decade. During the recovery phase of the 1980s, unexpected high abundance of Stephanodiscus minutulus leads to strong overestimation of TP concentrations. Similarly, the reconstructed primary productivity only disagrees with the experimental data for some years in the last decade. Sensitivity of the sedimentary pigment model as well as the relatively reduced sampling dates likely explains this discrepancy. Similarities are also evident in the temporal diatom assemblage variations of an additional three sub alpine Italian lakes. As well, the palaeolimnological reconstruction for Lake Maggiore parallels that for Lake Constance, another large sub alphine lake located north of the Alps. 113 articolo pubblicato 03_QuatInt_2004_Lami_Guilizzoni.pdf Articolo in rivista Pergamon. 1040 6182 Quaternary international Quaternary international Quat. int. aldo.marchetto MARCHETTO ALDO piero.guilizzoni GUILIZZONI PIERO andrea.lami LAMI ANDREA leonardo.langone LANGONE LEONARDO TA.P02.005.002 Uso della paleolimnologia come strumento per lo studio del paleoclima e dell evoluzione climatica TA.P02.028.002 Struttura dei margini continentali, emissione dei fluidi attraverso di essi, e impatto sugli ecosistemi |
