Regime Shifts and Tipping Points

Abstract

Regime shifts in inland waters are strong, abrupt, persistent changes in the structure and functioning of a system. Regime shifts typically describe transitions between contrasting ecological states. For instance, the shift from a clear lake, dominated by submerged vegetation, to a turbid, phytoplankton-dominated lake is a regime shift. In this chapter we aim to explain (1) what regime shifts and tipping points are, (2) how they are manifested in inland waters, (3) how they are linked to ecosystem functioning and (4) if and how we can detect regime shifts in advance to prevent an ecosystem from tipping. Different approaches had been explored to predict regime shifts and to identify tipping points including models, experimental approaches, and analysis of field data focusing on the identification of discontinuities or multimodality, or critical slowing down. Knowledge about regime shifts is widely applied in management, for instance through the application of biomanipulation to short-cut hysteresis when aiming to convert a turbid phytoplankton dominated system back to a clear system with submerged vegetation. In this chapter we explain the different concepts related to regime shifts and tipping points using examples from field observations, experiments and models. We conclude that regime shifts in inland waters strongly affect ecosystem functioning and the services associated with alternative regimes. Based on current insights, anticipating regime shifts remains a challenge.