Top-predator recovery abates geomorphic decline of a coastal ecosystem

• 成果类型: Article
• 署名作者: Hughes, Brent B.; Beheshti, Kathryn M.; Tinker, M. Tim; Angelini, Christine; Endris, Charlie; Murai, Lee; Anderson, Sean C.; Espinosa, Sarah; Staedler, Michelle; Tomoleoni, Joseph A.; Sanchez, Madeline; Silliman, Brian R.
• 署名单位: California State University System; Sonoma State University; Duke University; University of California System; University of California Santa Cruz; University of California System; University of California Santa Barbara; State University System of Florida; University of Florida; Moss Landing Marine Laboratories; Fisheries & Oceans Canada; Simon Fraser University; Monterey Bay Aquarium Research Institute; United States Department of the Interior; United States Geological Survey
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5190
• DOI: 10.1038/s41586-023-06959-9
• 发表日期: 2024-02-01
• 关键词: sea-level rise; individual variation; kelp forests; die-off; ecology; habitat; eutrophication; specialization; estuaries; collapse

摘要

The recovery of top predators is thought to have cascading effects on vegetated ecosystems and their geomorphology1,2, but the evidence for this remains correlational and intensely debated3,4. Here we combine observational and experimental data to reveal that recolonization of sea otters in a US estuary generates a trophic cascade that facilitates coastal wetland plant biomass and suppresses the erosion of marsh edges-a process that otherwise leads to the severe loss of habitats and ecosystem services5,6. Monitoring of the Elkhorn Slough estuary over several decades suggested top-down control in the system, because the erosion of salt marsh edges has generally slowed with increasing sea otter abundance, despite the consistently increasing physical stress in the system (that is, nutrient loading, sea-level rise and tidal scour7-9). Predator-exclusion experiments in five marsh creeks revealed that sea otters suppress the abundance of burrowing crabs, a top-down effect that cascades to both increase marsh edge strength and reduce marsh erosion. Multi-creek surveys comparing marsh creeks pre- and post-sea otter colonization confirmed the presence of an interaction between the keystone sea otter, burrowing crabs and marsh creeks, demonstrating the spatial generality of predator control of ecosystem edge processes: densities of burrowing crabs and edge erosion have declined markedly in creeks that have high levels of sea otter recolonization. These results show that trophic downgrading could be a strong but underappreciated contributor to the loss of coastal wetlands, and suggest that restoring top predators can help to re-establish geomorphic stability. Sea otters recolonizing an estuary in California indirectly reduce erosion by reducing burrowing crab abundance, suggesting that restoring predators could be a key mechanism to improve the stability of coastal wetlands and other ecosystems.