Species richness accelerates marine ecosystem restoration in the Coral Triangle

Significance

The exceptional diversity of species in the coral reefs, seagrass meadows, and mangrove forests of the Coral Triangle and the many ecological functions and benefits to humans they provide have made them a high priority for conservation and fisheries management. Nevertheless, their degradation continues and calls for effective restoration. In an experimental restoration, we demonstrated that planting mixtures of diverse seagrass species improves their overall survival and growth and thus the trajectory toward successful restoration. Incorporating species diversity into restoration heralds a shift in practice from establishing a single founder species, and recognizes the widely documented positive effects that biodiversity has on ecosystem function and services. Biodiversity is often a restoration goal, but it also promises a means to improve success.

Abstract

Ecosystem restoration aims to restore biodiversity and valuable functions that have been degraded or lost. The Coral Triangle is a hotspot for marine biodiversity held in its coral reefs, seagrass meadows, and mangrove forests, all of which are in global decline. These coastal ecosystems support valuable fisheries and endangered species, protect shorelines, and are significant carbon stores, functions that have been degraded by coastal development, destructive fishing practices, and climate change. Ecosystem restoration is required to mitigate these damages and losses, but its practice is in its infancy in the region. Here we demonstrate that species diversity can set the trajectory of restoration. In a seagrass restoration experiment in the heart of the Coral Triangle (Sulawesi, Indonesia), plant survival and coverage increased with the number of species transplanted. Our results highlight the positive role biodiversity can play in ecosystem restoration and call for revision of the common restoration practice of establishing a single target species, particularly in regions having high biodiversity. Coastal ecosystems affect human well-being in many important ways, and restoration will become ever more important as conservation efforts cannot keep up with their loss.