Work

Balancing restoration and conservation: Source material selection for restoration of an endangered Australian seagrass, Posidonia australis

Year: 2025

Type: article

Abstract: Restoration of endangered species is an essential but challenging feature of the global response to biodiversity loss. Sourcing restoration material from endangered species must not compromise conservation of existing populations, which can limit large-scale restoration opportunities. On Australia’s east coast, Posidonia australis is a slow-growing endangered seagrass with limited seed production. Restoration relies on adult fragments sourced through direct translocation from existing meadows, or from naturally detached "beach-cast" fragments. We assessed the relative success of these two donor sources for restoration and the effect of fragment size by monitoring shoot density, necrosis, and epiphyte cover over 18 months. Directly translocated fragments maintained a shoot density of 97%, while beach-cast fragments initially declined before stabilising at 60% of the original shoot density. Notably, mixed-source plots (50% from each donor source) retained 91% shoot density. Fragment size (1–2 shoots vs. >2 shoots) did not significantly impact seagrass density, indicating that smaller fragments—common in beach-cast material—remain viable for restoration. Beach-cast seagrass exhibited high necrosis rates in the first three months, likely due to physiological stress from beaching, but their long-term performance was comparable to translocated fragments. These findings highlight a key trade-off in P. australis restoration: while direct translocation yields higher density retention, it is constrained by legal protection and ecological concerns surrounding donor meadow harvesting. Beach-cast fragments, though more readily available, exhibit higher initial losses after planting. A mixed-source approach may provide an optimal balance, leveraging the resilience of translocated fragments while minimising the ecological impact of donor harvesting.

Source: Biological Conservation

DOI: 10.1016/j.biocon.2025.111621

Authors: Madelaine Langley, Erin McCosker, Alistair G.B. Poore, Adriana Vergés

Institution: UNSW Sydney

Language: English

Topic: Marine and coastal plant biology

Subfield: Oceanography

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDGs: Life below water, Life on land

Open Access status: hybrid

Estimated APC paid: $3,830