| Abstract | To understand interactions of lake physical characteristics, trophic dynamics and climate in Lago Maggiore, we compare longterm limnological and meteorological monitoring data and results from sediment cores. We include analyses of nutrients, pigments, diatoms and cladoceran microfossils. Over the past decades, caloric content increased. Eutrophication from the 1960s to early 1980s was followed by oligotrophication. DDTs, PCBs and Hg showed high contamination in the '60s, compared to point source inputs in the '90s. Algal biomass was predicted by total pigments and some algal specific carotenoids. Following nutrient enrichment, Chydorus sphaericus, and total abundance of cladocerans changed inversely with trophic status. Fewer large Daphnia since the late '80s matched an increase in with subfossil Eubosmina mucro lengths. Both were explained by the 10-fold increase in Bythotrephes longimanus from 1987 to 1993, when an increase of its mean annual population density occurred during warmer winter and springs. Bythotrephes remained abundant and further increased during the following 10 years as water temperature increased. We conclude that warmer water affects food chains indirectly by changing habitat use and predator-prey interactions. Relative abundances of Daphnia and its peak population density in the warm year of the oligotrophic period (2003) were close to the record from the mesotrophic period in 1982, supporting the hypothesis that warming can produce a eutrophication-like signal. The study illustrates the complexity of biological responses to synchronous changes in multiple drivers (e.g., eutrophication, fish introduction, ban of fish harvesting, chemical pollution, and climate) and, despite this complexity, how Lago Maggiore responded to multiple stressors. |
| Authors | Guilizzoni, Piero ;Levine, Suzanne N. ;Manca, Marina ;Marchetto, Aldo ;Lami, Andrea ;Ambrosetti, Valter;Brauer, Achim ;Gerli, Stefano;Carrara, Elisabetta A. ;Rolla, Angelo ;Guzzella, Licia;Vignati, Davide |
| Text | 219798 2012 10.4081/jlimnol.2012.e1 Human impact climate change palaeolimnology time series Ecological effects of multiple stressors on a deep lake Lago Maggiore, Italy integrating neo and palaeolimnological approaches Guilizzoni, Piero ;Levine, Suzanne N. ;Manca, Marina ;Marchetto, Aldo ;Lami, Andrea ;Ambrosetti, Valter;Brauer, Achim ;Gerli, Stefano;Carrara, Elisabetta A. ;Rolla, Angelo ;Guzzella, Licia;Vignati, Davide CNR ISE, Pallanza Verbania ;Rubenstein School of Environment and Natural Resources, Aiken Center University of Vermont, Burlington, VT 05405, USA ;CNR ISE, Pallanza Verbania ;CNR ISE, Pallanza Verbania ;CNR ISE, Pallanza Verbania ;CNR ISE, Pallanza Verbania ;GFZ German Research Centre for Geosciences, Section 5.2 Climate Dynamics and Landscape Evolution, 14473 Potsdam, Germany ;CNR ISE, Pallanza Verbania ;Water Division, Bureau of Meteorology, Melbourne, Vic. 3008, Australia ;CNR ISE, Pallanza Verbania ;CNR IRSA, Brugherio ;CNR IRSA, Brugherio To understand interactions of lake physical characteristics, trophic dynamics and climate in Lago Maggiore, we compare longterm limnological and meteorological monitoring data and results from sediment cores. We include analyses of nutrients, pigments, diatoms and cladoceran microfossils. Over the past decades, caloric content increased. Eutrophication from the 1960s to early 1980s was followed by oligotrophication. DDTs, PCBs and Hg showed high contamination in the 60s, compared to point source inputs in the 90s. Algal biomass was predicted by total pigments and some algal specific carotenoids. Following nutrient enrichment, Chydorus sphaericus, and total abundance of cladocerans changed inversely with trophic status. Fewer large Daphnia since the late 80s matched an increase in with subfossil Eubosmina mucro lengths. Both were explained by the 10 fold increase in Bythotrephes longimanus from 1987 to 1993, when an increase of its mean annual population density occurred during warmer winter and springs. Bythotrephes remained abundant and further increased during the following 10 years as water temperature increased. We conclude that warmer water affects food chains indirectly by changing habitat use and predator prey interactions. Relative abundances of Daphnia and its peak population density in the warm year of the oligotrophic period 2003 were close to the record from the mesotrophic period in 1982, supporting the hypothesis that warming can produce a eutrophication like signal. The study illustrates the complexity of biological responses to synchronous changes in multiple drivers e.g., eutrophication, fish introduction, ban of fish harvesting, chemical pollution, and climate and, despite this complexity, how Lago Maggiore responded to multiple stressors. 71 Published version Ecological effects of multiple stressors on a deep lake Lago Maggiore, Italy integrating neo and palaeolimnological approaches 2012_A0_003.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. ROLLA ANGELO GERLI STEFANO valter.ambrosetti AMBROSETTI VALTER aldo.marchetto MARCHETTO ALDO piero.guilizzoni GUILIZZONI PIERO liciamaria.guzzella GUZZELLA LICIA MARIA davideanselmoluigi.vignati VIGNATI DAVIDE ANSELMO LUIGI andrea.lami LAMI ANDREA marinamarcella.manca MANCA MARINA MARCELLA TA.P02.014.002 Impatto dei cambiamenti globali sugli ecosistemi acquatici |
