Prioritising actions over space and time in multi-habitat ecological restoration: Insights from indicator species in coastal seascapes

Restoring multi-habitat landscapes requires decisions on habitat placement and sequence. Animal distributions can indicate landscape change, yet few studies have leveraged such data to inform landscape-scale restoration decisions. We investigated this using data describing fish assemblages from 13 estuaries and four coastal habitats (seagrass, mangroves, reefs, log snags) in southeast Queensland, Australia, over two years (n > 1000 surveys). Distribution models for five indicator species, fish abundance, fish richness, and harvestable fish abundance were combined to map habitat restoration benefits for all fish metrics in unison and constrained to suitable growth areas for each habitat for an exemplar estuary. Restoration, regardless of habitat type, had greater predicted benefits for fish when implemented at sites proximal to the ocean, and existing seagrass and mangroves. We then tested the effects of restoring the top 5% of sites, followed by the 5th to 10th percentile of sites for each habitat. For the top 5% prioritisation, rocky/oyster reefs should be restored first because they provide the greatest modelled benefit for fish (59.1% of the maximum theoretical outcome), followed by seagrass (43.8%), log snags (39.2%) and mangroves (35%). Updating the distribution models after restoring the top 5% of sites shifted the priority of habitats with mangroves becoming most beneficial and boosted outcomes by 20.6–30.8% compared to the original 5th to 10th percentile sites. Results underscore the importance of integrating remnant and newly restored habitat patches into restoration planning, emphasising that the strategic timing and placement of actions can maximise synergistic benefits.