Immanent conditions determine imminent collapses: nutrient regimes define the resilience of macroalgal communities

Jordi Boada, Rohan Arthur, David Alonso, Jordi F Pagès, Albert Pessarrodona, Silvia Oliva, Giulia Ceccherelli, Luigi Piazzi, Javier Romero, Teresa Alcoverro

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Predicting where state-changing thresholds lie can be inherently complex in ecosystems characterized by nonlinear dynamics. Unpacking the mechanisms underlying these transitions can help considerably reduce this unpredictability. We used empirical observations, field and laboratory experiments, and mathematical models to examine how differences in nutrient regimes mediate the capacity of macrophyte communities to sustain sea urchin grazing. In relatively nutrient-rich conditions, macrophyte systems were more resilient to grazing, shifting to barrens beyond 1 800 g m-2 (urchin biomass), more than twice the threshold of nutrient-poor conditions. The mechanisms driving these differences are linked to how nutrients mediate urchin foraging and algal growth: controlled experiments showed that low-nutrient regimes trigger compensatory feeding and reduce plant growth, mechanisms supported by our consumer-resource model. These mechanisms act together to halve macrophyte community resilience. Our study demonstrates that by mediating the underlying drivers, inherent conditions can strongly influence the buffer capacity of nonlinear systems.

Original languageEnglish
JournalProceedings of the Royal Society of London: series B
Volume284
Issue number1851
DOIs
Publication statusPublished - 29 Mar 2017
Externally publishedYes

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