WP3 Variations in the terrestrial component of water cycle Task Effects of climate and hydrological changes on the thermal structure and water storage in sub-alpine lakes and temperature related production/respiration variations Bologna, 2007, May 2 nd RL5 Kick-Off Meeting Gianni Tartari & Diego Copetti

Physical state of lakes Trophic state of lakes

Lake responses to climate change: Modification thermal stratification (TEMPERATURE), Lake hydrodynamics (RIVERS INFLOW, WIND) and large-scale circulation (CURRENTS), Chemical/trophic water quality (HYDROLOGY, POLLUTANT TRANSPORT), Ecological quality (BIOCENOSYS MODIFICATIONS)

Effects on shallow lakes higher temperatures give longer thermal stability with reduction of sediments resuspension but, on the contrary, the increasing of oxygen depletion in the hypolimnion will increments the phosphorous internal loads in eutrophic water bodies; lower nutrient input and lower water levels may stimulate the growth of submerged macrophytes with positive feedback effects on the ecological state warmer summers favouring zooplanktivores cyprinid fish at the expense of piscivores fish; changes to smaller average size of fish may directly or indirectly (by affecting grazers) favour phytoplankton growth and dominance of potential toxic cyanobacteria; enhanced risk of fish kill due to cyanobacteria and anoxic conditions; higher salinity and droughts may be detrimental to the ecological status and reduce biodiversity; increase in salinity will also exacerbate eutrophication because key-grazers of phytoplankton are affected and because of increased top-down control in such lakes. Lake responses to climate change

Effects on deep lakes higher temperatures during spring and autumn will prolong the stratification period; in nutrient-rich lakes, this may enhance the risk of oxygen depletion in the bottom water (hypolimnion) and lead to higher phosphorous release from the sediment, just as it may change the biomass, composition and distribution of phytoplankton in time and space; a temperature increase will mediate a shift in fish composition and fish size, resulting in enhanced predation on zooplankton and thus reduced grazing on phytoplankton. Like in shallow lakes, improvements are expected in the Mediterranean area due to the reduced loading, though this may be counterbalanced by increased dominance of potential toxic cyanobacteria; the reducing hydraulic loading will icrease the retention and accumulation of nutrients in southern lakes. Lake responses to climate change

Sub-task TS1 1.data collection (meteorological, hydrological, lake level, temperature etc. (6 month); 2.model calibration (24 months); 3.long term scenarios on hydrological and hydrodynamics lake evolution (9 months). TS2 4.lake water temperature scenarios will be used to infer on the effects on lake biology (production/respiration rate). Task Effects of climate and hydrological changes on the thermal structure and water storage in sub-alpine lakes and temperature related production/respiration variations Modelling and experimental activities will be carried out in two sub-alpine lakes: Lake Pusiano (mid shallow) and Lake Como (large deep). Aim To build up a model-based tool for predicting long-term scenarios of variations in thermal structure and water storage in lakes and to infer about possible temperature related changes in the lake production/respiration budget Approach To combine the results of hydrological and hydrodynamics models using meteorological scenarios as result of other RLs/tasks of the project.

Lake Pusiano Catchment Area94.8km² Maximum altitude1453m Average altitude638m Lake Area4,99km² Volume 69.2  10 6 m³ Avarege altitude259m a.s.l Maximum depth24m Average depth14m Theoretical water renewal time 0.8year Lake Pusiano is eutrophic

Lake Pusiano CatchmentLake Climatological variables Hydrology Rivers water quality SWAT QUAL 2E Daily inflow Chemistry:  Nutrients;  Main ions. Biology:  Phytoplankton;  Zooplankton. Hydrodynamic: DYRESM Ecological: CAEDYM Land use Anthropization Geology etc. GIS Nutrient loads Lake level Thermal profile

Lake Como Catchment Area4508km² Maximum altitude4050m Lake Area145km² Volume22.5km³ Avarege altitude198m a.s.l Maximum depth425m Average depth155m Theoretical water renewal time 4.4year Lake Como is mesotrophic Como Pusiano

Lake Como CatchmentLake Climatological variables Hydrology Rivers water quality Annual/monthly inflow Chemistry:  Nutrients;  Main ions. Biology:  Phytoplankton; Hydrodynamic: DYRESM Ecological: CAEDYM Land use Anthropization Geology etc. GIS Nutrient loads LDS Network Water level

LDS Network on Lake Como 425 m LDS1 LDS3 LDS2

DYRESM (DYnamic Reservoir Simulation Model) SWR LWR Momentum LWR Epi Hypo Meta Input file:  configuration,  meteorological forcing,  lake morphometry,  Inflows,  outflow,  initial profile,  hydrodynamic parameters. The hydrodynamic model Inflow Outflow

CAEDYM (Computational Aquatic Ecosystem DYnamics Model) Inflow Outflow Gas exchange (e.g. O 2, CO 2, NO x ) Dissolved flux (e.g. PO 4, NH 4 ) Resuspension (e.g. POP, PON) Up take Solar radiation Sedimentation The ecological model

Gen-Mar 2005 Gen-Mar 2007 Lake Como

Different interannual response of lake water surface temperature Jan-Mar Lake Como

Oxygen depletion in the hypolimnion and consequent nutrient release at the water-sediment interface; Sediments resuspension, Effects of nutrient load change on the lake production (chlorophyll a) Possible shift from green algae to cyanobacteria. Effects of the thermal stability on ecological state Possible scenarios

RL2 - The Mediterranean Region and the Global Climate System Li Laurent (CNRS/IPSL), Silvio Gualdi (INGV) WP2.4: Coordination on production of scenarios and distribution of datasets Responsible: Li Laurent (CNRS/IPSL) RL3 - Radiation, clouds, aerosols and climate change Le Treut Herve (CNRS/LMD-IPSL), Lelieveld Jos (MPICH ) WP3.3: Impacts of future climate change on the surface radiation Responsible: Lelieveld Jos (MPICH) RL5 - Water Cycle Alpert Pinhas (TAU), Vurro Michele (IRSA-CNR) WP5.1: Analysis of changes in Atmospheric water budget Responsible: Alpert Pinhas (TAU) WP5.2: Variations in the precipitation component of the water cycle in the Mediterranean Region Responsible: Trigo Ricardo (ICAT-UL) RL7 - Impacts of Global Change on Ecosystems and the services they provide Valentini Riccardo (UNITUSCIA), Holger Hoff (PIK) WP7.5: Climate impacts on biogeochemical cycling Responsible: Reichstein Markus (MPIBGC) Links whit other CIRCE’s RLs&WPs