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.
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