We conducted a field experiment of nutrient addition in a coastal lagoon during winter-spring 2020 using mesocosms. We compared a continuous addition of nutrients during one month with single addition of the whole amount of nutrients at the beginning.
We analysed the changes in the zooplankton composition in several new and old lagoons in La Pletera salt marshes subjected to a restoration project. we did not find significant differences in the zooplankton community between the old and new lagoons. The seasonal variation in the zooplankton communities was strongly affected by the seasonal hydrological flooding – confinement pattern, which did not differ between the old and new lagoons.
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.