Identifying critical transitions in seasonal shifts of zooplankton composition in a confined coastal salt marsh

Quintana et al. (2021) – Aquatic Sciences, 83: 69.

We applied the alternative stable states theory to analyse if seasonal zooplankton shifts behave as critical transitions between two different equilibriums: de dominances of the calanoid Eurytemora velox and those of the rotifer Brachionus gr. plicatilis. We use high frequency temperature and oxygen data provided by sensors installed in situ as a measure of ecosystem state. We investigate if shifts in zooplankton composition are determined by a threshold in these variables or, on the other hand, some inertia between stable states occur. Our results show that shifts between dominant zooplankton species in La Pletera salt marshes are asymmetric. The shift to a Eurytemora situation is mainly driven by a decrease in temperature, with a threshold close to 19 °C. We also found some hysteresis and some resistance to change when a critical transition is approaching. Top-down and bottom-up forces appear to have no significant effect on shifts.

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