Séminaire
The California Current Ecosystem Long-Term Ecological Research (CCE-LTER) site seeks to understand the mechanistic basis for abrupt changes in ecosystem state in this major Eastern Boundary Current upwelling ecosystem. We are analyzing the consequences of multiple scales of forcing – including ENSO, the Pacific Decadal Oscillation, and long-term secular trends – on the planktonic ecosystem at the base of the food web. At times there are abrupt changes in ecosystem state in this region that have been attributed to changes in dynamic “regimes.” However, we have advanced a simpler Double Integration Hypothesis that explains such abrupt ecological shifts as a consequence of reddening of the variance spectrum, illustrated by a simple Autoregressive I model. Our CCE-LTER site is actively involved in developing a mechanistic understanding of these shifts, in order to develop a quantitative framework for forecasting the future state of the planktonic food web and the organisms that depend upon it. Our site research includes a multidisciplinary group of scientists who utilize complementary approaches in an iterative manner: experimental work at sea, extensive multi-scale ocean observations, integrated with modeling. The CCE-LTER site is fortunate to build upon the nearly 7-decade observational record of the CalCOFI program, an important space-resolving ocean time series.
marina@locean-ipsl.upmc.fr