Written by Michael Sievers
Restoration is a key challenge of the 21st century, as ecosystems are increasingly lost and degraded. As efforts to restore ecosystem accelerate, it is critical investments are targeted to most effectively mitigate and reverse habitat and biodiversity loss.
One likely, yet largely overlooked, impediment to effective restoration of habitat-forming organisms (e.g., seagrass, mangroves, and corals) is failing to explicitly consider non-habitat forming animals (e.g., fish, bivalves, megaherbivores).
These animals perform important functions necessary for ecosystem persistence and resilience, and drive many of the services restoration seeks to enhance.
Restoration without animals is like gin and tonic without the gin; there’s something important missing, it doesn’t quite work, and it’s unlikely to achieve the desired outcome.
In our new paper published in BioScience, we explain how knowledge of interactions between animals and restored coastal habitats could be better incorporated into restoration planning, implementation, and evaluations of success. By doing so, efforts to restore coastal systems can improve the chance of success.
Figure 1. Interactions between animals and habitat-forming species along the coast are critical for healthy ecosystems. Symbols curtesy of the Integration and Application Network (ian.umces.edu/media-library)
Several experiments from around the world have shown how manipulating animals can have huge effects. For instance, translocating clams into restored seagrass led to a 500% expansion in patch size due to increased nitrogen availability (Figure 2A). Adding mussels to plots with transplanted saltmarsh similarly enhances plant growth and clonal expansion by 50% via reductions in sulphur and increased nutrient levels (Figure 2B).
Figure 2. Examples for when explicit consideration of animals enhanced coastal restoration outcomes.
On the other hand, some animals are bad for restoration, such as bioturbating lugworms that disturb planted seagrass. By adding a barrier underneath transplanted seagrass, interactions between seagrass and bioturbating lugworms were vastly reduced, leading to 50-140% greater seagrass growth (Figure 1C).
Identifying when, why, and how to directly manipulate or support animals can enhance outcomes for habitat-forming species. We provide a conceptual framework to identify actions that could lead to better restoration outcomes, regardless of the ultimate restoration objective (Figure 3)
Figure 3. Contexts in which animals could be manipulated and supported within coastal restoration, and the actions that can lead to positive outcomes.
Through this and our continued research with the Global Wetlands Project, we hope to encourage scientists and managers to better incorporate animals into coastal restoration planning, implementation, and monitoring.
Catchment to Coast 