Restored seagrass rapidly provides high-quality habitat for mobile animals

Abstract

Restoring seagrasses provides habitat for animals, many of which play vital roles in the maintenance, persistence, and resilience of seagrass habitat. Understanding how the maturity of restored seagrass habitats influences the colonization and condition of associated animal communities can provide insights to inform restoration methods and improve outcomes. We surveyed mobile fauna at 132 sites in Vejle fjord, Denmark, in natural seagrass, bare sand, and restored seagrass (Zostera marina; eelgrass). Seagrass was transplanted 1, 2, 3, or 4 years ago (2019–2022). In addition to abundance and diversity metrics, we quantified individual condition metrics, and conducted metabolomic analysis on lesser pipefish (Syngnathus rostellatus). Seagrass-associated species rapidly colonized restored habitats, such as common periwinkles and Baltic prawns. Bare sites and 1-year-old sites harbored very similar communities. A distinct shift thereafter saw restored communities converge irrespective of habitat age, and were similar to natural sites. We observed species-specific trends in abundance related to seagrass cover that were positive, negative, or unimodal; abundance was highest when seagrass cover was intermediate (approximately 45–70%). Morphometric indices for three fish species, and metabolomic profiles for lesser pipefish, did not differ among sites. Our study adds to the growing body of literature showing rapid faunal colonization of restored Z. marina habitats, particularly when restored in close proximity to natural eelgrass. This provides impetus for continued investments in eelgrass restoration and suggests little need for building in time lags when including biodiversity benefits of seagrass restoration in natural capital assessments for this species.