Scheda di dettaglio – i prodotti della ricerca
| Dato | Valore |
|---|---|
| Title | A long-term multi-proxy record of varved sediments suggests climate-induced mixing-regime shift in a large hard-water lake similar to 5000 years ago |
| Abstract | The long-term terrestrial and aquatic ecosystem dynamics spanning between approximately 6200 and 4800 cal BP were investigated using pollen, diatoms, pigments, charcoal, and geochemistry from varved sediments collected in a large stratified perialpine lake, Lago Grande di Avigliana, in the Italian Alps. Marked changes were detected in diatom and pigment assemblages and in sediment composition at similar to 4900 cal BP. Organic matter rapidly increased and diatom assemblages shifted from oligotrophic to oligo-mesotrophic planktonic assemblages suggesting that nutrients increased at that time. Because land cover, erosion, and fire frequency did not change significantly, external nutrient sources were possibly not essential in controlling the lake-ecosystem dynamics. This is also supported by redundancy analysis, which showed that variables explaining significant amounts of variance in the diatom data were not the ones related to changes in the catchment. Instead, the broad coincidence between the phytoplankton dynamics and rising lake-levels, cooler temperatures, and stronger spring winds in the northern Mediterranean borderlands possibly points to the effects of climate change on the nutrient recycling in the lake by means of the control that climate can exert on mixing depth. We hypothesize that the increased P-release rates and higher organic-matter accumulation rates, proceeded by enhanced precipitation of iron sulphides, were possibly caused by deeper and stronger mixing leading to enhanced input of nutrients from the anoxic hypolimnion into the epilimnion. Although we cannot completely rule out the influence of minor land-cover changes due to human activities, it may be hypothesized that climate-induced cumulative effects related to mixing regime and P-recycling from sediments influenced the aquatic-ecosystem dynamics. |
| Source | Journal of limnology (Testo stamp.) 73 (2), pp. 211–222 |
| Keywords | Varvespigmentspollendiatomsmu XRFstratificationclimate changeEurope |
| Journal | Journal of limnology (Testo stamp.) |
| Editor | Istituto per lo Studio degli Ecosistemi., Verbania Pallanza, Italia |
| Year | 2014 |
| Type | Articolo in rivista |
| DOI | 10.4081/jlimnol.2014.907 |
| Authors | Walter Finsinger; Thierry Fonville; Emiliya Kirilova; Andrea Lami; Piero Guilizzoni; Andre F. Lotter |
| Text | 328503 2014 10.4081/jlimnol.2014.907 ISI Web of Science WOS 000342807000002 Scopus 2 s2.0 84902651013 Varves pigments pollen diatoms mu XRF stratification climate change Europe A long term multi proxy record of varved sediments suggests climate induced mixing regime shift in a large hard water lake similar to 5000 years ago Walter Finsinger; Thierry Fonville; Emiliya Kirilova; Andrea Lami; Piero Guilizzoni; Andre F. Lotter University of Utrecht; Centre National de la Recherche Scientifique CNRS ; Inst Ecosyst Study CNR ISE The long term terrestrial and aquatic ecosystem dynamics spanning between approximately 6200 and 4800 cal BP were investigated using pollen, diatoms, pigments, charcoal, and geochemistry from varved sediments collected in a large stratified perialpine lake, Lago Grande di Avigliana, in the Italian Alps. Marked changes were detected in diatom and pigment assemblages and in sediment composition at similar to 4900 cal BP. Organic matter rapidly increased and diatom assemblages shifted from oligotrophic to oligo mesotrophic planktonic assemblages suggesting that nutrients increased at that time. Because land cover, erosion, and fire frequency did not change significantly, external nutrient sources were possibly not essential in controlling the lake ecosystem dynamics. This is also supported by redundancy analysis, which showed that variables explaining significant amounts of variance in the diatom data were not the ones related to changes in the catchment. Instead, the broad coincidence between the phytoplankton dynamics and rising lake levels, cooler temperatures, and stronger spring winds in the northern Mediterranean borderlands possibly points to the effects of climate change on the nutrient recycling in the lake by means of the control that climate can exert on mixing depth. We hypothesize that the increased P release rates and higher organic matter accumulation rates, proceeded by enhanced precipitation of iron sulphides, were possibly caused by deeper and stronger mixing leading to enhanced input of nutrients from the anoxic hypolimnion into the epilimnion. Although we cannot completely rule out the influence of minor land cover changes due to human activities, it may be hypothesized that climate induced cumulative effects related to mixing regime and P recycling from sediments influenced the aquatic ecosystem dynamics. 73 Published version Articolo 2014_Journal_of_Limnology_73_s2_211_222.pdf Articolo in rivista Istituto per lo Studio degli Ecosistemi. 1129 5767 Journal of limnology Testo stamp. Journal of limnology Testo stamp. J. limnol. Testo stamp. Journal of limnology. Testo stamp. piero.guilizzoni GUILIZZONI PIERO andrea.lami LAMI ANDREA TA.P02.014.002 Impatto dei cambiamenti globali sugli ecosistemi acquatici |