13 Mag. 2014 - Isabella Bertani

Seminar Bertani

Regime shift triggered by an extreme climatic event in an oligotrophic mountain lake

Presenta: Isabella Bertani ( LifeWatch-Ita, Centro Tematico Interazioni, CNR-IBAF, Monterotondo Scalo )

Climatic extremes, especially heatwaves and droughts, have increased in frequency, duration and magnitude in many regions of the world as a result of climate change, and this trend is predicted to continue, thereby raising urgent questions regarding their ecosystem-scale consequences on freshwater systems. We explored the impacts of a summer heatwave on a small, stratifying lake that is part of the Italian LTER Network. A sudden transition from a phytoplankton- to a macrophyte-dominated regime occurred during the heatwave. We investigated candidate mechanisms driving the switch from pelagic to benthic control of primary production, and we examined physico-chemical and biological time series to identify the major ecosystem-level consequences of the switch. Our results provide evidence of abrupt and extensive ecological changes that are indicative of a regime shift. We show that ecological implications of the shift propagate across multiple trophic levels and determine marked changes in community structure that persist long after the climatic anomaly.

click to download notice of seminar