A project undertaken at Deakin University, and supervised by Dr Stacey Trevathan-Tackett.
This project aimed to explore innovative methods for restoring degraded coastal ecosystems, particularly saltmarshes, which have been diminished due to agricultural and industrial use. The project focused on trialling novel interventions, such as biodegradable habitats, to improve soil and plant responses following revegetation. We employed methods such as direct seeding and transplanting pioneer saltmarsh species Salicornia quinqueflora into BESE-elements biodegradable structures. Biodegradable Ecosystem restoration Elements (BESE-elements) are made from a starch biopolymer and they help rescue local currents, waves etc, providing stability for transplanted plants. We also monitored belowground microbiomes to improve our understanding of the role bacteria and fungi play in plant health and stress.
We observed varying degrees of success in vegetation and seed germination efforts. Transplant survival rates were generally low, not exceeding 6%, likely due to challenging soil conditions and environmental stressors, such as high compaction and limited hydrological movement and therefore no organic matter inputs. There was a slight increase in vegetative cover within the biodegradable structures, suggesting some improvement in plant growth following transplantation. However, sediment accumulation in these structures was minimal, with an average build-up of just 3.7 mm over 24 months. These outcomes indicate that while biodegradable structures may offer some benefits, limited tidal influence in the area hinders their effectiveness in stabilising soil and facilitating vegetation growth.
The microbial studies conducted revealed significant shifts in bacterial and fungal diversity and composition, influenced by restoration conditions and soil compartments (bulk soil vs. rhizosphere). We identified key taxa enriched under specific conditions including between the use of transplants into BESE-elements and the natural saltmarsh. The results provide insights into microbial assembly processes. These findings offer valuable data for selecting microbial candidates for future interventions, promoting soil health, and enhancing restoration practices in saltmarsh ecosystems.
This project contributes valuable insights into effective coastal restoration strategies by elucidating how different restoration techniques and environmental conditions affect plant and microbial establishment. The findings aid in identifying key microbial taxa and optimal conditions for saltmarsh recovery, offering guidance for future restoration projects. By gaining new knowledge on the interactions between soil, vegetation, and microbial communities in temperate saltmarsh, this work supports broader efforts to improve biodiversity and carbon sequestration in degraded coastal areas, ultimately fostering more resilient ecosystems.