Nutrient enrichment has been found to have a destabilizing effect on ecosystems in mathematical models, and laboratory and field experiments. Further modeling efforts have demonstrated that nutrient enrichment in one node of a meta-ecosystem can destabilize consumer-resource dynamics in connected nodes. We tested the destabilizing effect of nutrient enrichment on local and distal dynamics in freshwater aquatic mesocosms at different levels of enrichment and connectivity using single- and two-node networks using a fractional factorial experimental design. We performed weekly unidirectional water transfer from the upstream to the downstream nodes, replenishment of the upstream nodes with freshwater and nutrient addition for 15 weeks. Although we did not find that the usual measure for stability, the coefficient of variation of chlorophyll <i>a</i>, was affected by nutrient enrichment or connectivity, we found that average chlorophyll <i>a</i> increased in response to nutrient enrichment, whereas the effects of connectivity was exclusively time-dependent. Furthermore, we found that as connectivity between paired nodes increased, the cross-correlation of chlorophyll <i>a</i> over time between paired nodes also increased. Additionally, we found negative effects of nutrient enrichment on zooplankton diversity. Overall, our results support the model predictions that with sufficient levels of connectivity, the destabilization of an upstream node in a semi-natural meta-ecosystem can destabilize downstream nodes.

Primary Presenter: Egor Katkov, McGill University (egor.katkov@gmail.com)

Authors:

Egor Katkov, McGill University  (egor.katkov@gmail.com)

Michelle Gros, McGill University  (michelle.gros@mail.mcgill.ca)

Vincent Fugère, Université du Québec à Trois-Rivières  (vincent.fugere@uqtr.ca)

Melania Cristescu, McGill University  (melania.cristescu@mcgill.ca)

Gregor Fussmann, McGill University  (gregor.fussmann@mcgill.ca)

Andrew Gonzalez, McGill University  (andrew.gonzalez@mcgill.ca)