A spatial regime shift from predator to prey dominance in a large coastal ecosystem

• Published in: Communications biology Vol. 3; no. 1; p. 459
• Main Authors: Eklöf, Johan S, Sundblad, Göran, Erlandsson, Mårten, Donadi, Serena, Hansen, Joakim P, Eriksson, Britas Klemens, Bergström, Ulf
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 27.08.2020; Nature Publishing Group UK
• Subjects: Animal behavior; Aquatic ecosystems; Archipelagoes; Biology; Coastal ecosystems; Dispersal; Dominance; Ecology; Ecosystem structure; Ecosystems; Ekologi; Predation; Predators; Prey; Spatial heterogeneity; Baltic Sea
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-020-01180-0

Regime shifts in ecosystem structure and processes are typically studied from a temporal perspective. Yet, theory predicts that in large ecosystems with environmental gradients, shifts should start locally and gradually spread through space. Here we empirically document a spatially propagating shift in the trophic structure of a large aquatic ecosystem, from dominance of large predatory fish (perch, pike) to the small prey fish, the three-spined stickleback. Fish surveys in 486 shallow bays along the 1200 km western Baltic Sea coast during 1979-2017 show that the shift started in wave-exposed archipelago areas near the open sea, but gradually spread towards the wave-sheltered mainland coast. Ecosystem surveys in 32 bays in 2014 show that stickleback predation on juvenile predators (predator-prey reversal) generates a feedback mechanism that appears to reinforce the shift. In summary, managers must account for spatial heterogeneity and dispersal to better predict, detect and confront regime shifts within large ecosystems.