The Eden Estuary is an important site for nature and is designated for its local, national and international importance. Dr Clare Maynard of the University of St Andrews explains her work in restoring the Eden’s saltmarsh habitat and its significance in helping combat climate change, while PhD student Ben Taylor discusses his research into the carbon storage potential of saltmarsh.
The amazing saltmarshes that surround the Eden Estuary Site of Special Scientific Interest and Local Nature Reserve do two very important jobs: they provide wildlife with habitat and also protect the hinterland from coastal flooding and erosion. Saltmarsh habitats are a treasure trove of rich and unique wildlife and are increasingly valued for the role they play in keeping our ecosystems healthy. Here are just a few of the benefits they give wildlife – and us:
|Wildlife Benefits||Society Benefits|
|High tide refuge for waders & wildfowl||Stabilises and protects the shoreline|
|Feeding and roosting for a range of birds||Absorbs excess run-off during high rainfall|
|Nursery and shelter for fish and amphibians||Captures and stores carbon|
|Habitat for marine and terrestrial invertebrates||Provides nutrients and sediment for the marine ecosystem|
|Haven for specialist salt-adapted plant life||Provides recreation, such as wildfowling and bird watching|
Unfortunately, shoreline degradation and climate change are placing saltmarshes under increasing threat. But a long-standing stakeholder partnership is trying to combat this habitat loss and strengthen the Eden’s shoreline against rising sea levels.
Saltmarshes have suffered on many semi-developed shores around the world, because of past land use decisions (land claim, installation of earth embankments and coastal defences). These extra pressures, alongside sea level rise and the resulting increased number of storms, raise concerns about the resilience of these important habitats.
Given how important saltmarshes are and all the benefits they give us, researchers, government advisors and coastal landowners have together developed a saltmarsh restoration strategy. This will improve our understanding of how to make these important habitats more resilient.
The Eden project began way back in 1999, by transplanting a range of saltmarsh species, dug from local healthy marshes, in field trials around the estuary’s shoreline. SNH supported the work with local operation officers in Cupar helping out. Restoring saltmarshes is a slow process, with the transplants taking a few years to establish as a functioning marsh, but once thriving the vegetation serves to soften wave energy and slow down tidal currents. We learnt a lot: for example, transplants can easily be washed away immediately following planting, transplants are vulnerable to stress from waves during the first two to three years of establishment, and the relatively small donor marshes around the estuary can sustain only of a limited amount of harvesting.
SNH funded the ‘Saltmarshes on the Fringe’ project, which ran from 2014 to 2016, with its principle aim to plant up to two linear kms of new saltmarsh and link degraded marshes on the Eden. This would improve resilience to climate change and reverse decades of decline.
More importantly, it helped us to investigate if it was feasible to grow saltmarsh grasses in a greenhouse to transplant and trial differing methods to reduce washout rates.
We found we could increase by tenfold the number of transplants yielded from one ‘plug’ (spadeful) of natural marsh. We also learned how to grow a variety of different species from seed. After salt-hardening, the ‘ready-made’ transplants could be transferred from greenhouse to field to make planting out more efficient and less destructive to the natural marshes, making the process more sustainable and successful.
Although this project is seasonally dependant and labour-intensive, it has restored nearly two linear kilometres of shoreline, resulting in about 2,000 square metres of saltmarsh habitat.
From this project sprang a dedicated coastal plant hub project, called ‘Green Shores’, hosted by the St Andrews Links Trust. Funding support includes the Ministry of Defence, the St Andrews Links Trust, Fife Council and the Royal Dornoch Golf Club, which allowed the work to extend into the Tay Estuary and the Dornoch Firth. The community funder LEADER, in Fife (EU Rural Development Programme), is also on board, to develop opportunities and engage local communities in this latest spin-off.
Following on from the work on the ground, the Sediment Ecology Research Group at the University of St Andrews researches various aspects of the project and is now assessing how much carbon can potentially be captured through saltmarsh restoration. The ability of saltmarshes to store carbon is predominantly a product of long-lived, organic rich, anoxic sediment deposits which accumulate over time. Understanding how much carbon capture is increased after restoration will help measure both the changed rate and its monetary value. In the future, this ‘natural capital asset’ could help to subsidise such conservation initiatives – ensuring this important work continues.
This applied research project, unique to Scotland, provides a working example of how we can adapt our coasts. It sits alongside other Government-funded joint research which considers the changing exposure of our coastlines to erosion and flooding (Coastal Flooding in Scotland and Impacts of sea-level rise and storm surges due to climate change in the Firth of Clyde). Taken together, they show that climate change is affecting flood frequency and erosion on our shoreline, but ‘natural coastal defences’ (saltmarshes and dunes) play an important role in protecting over £13bn of assets (www.dynamiccoast.com). So, we must value and consider the defences nature provides within any future flood risk strategy and shoreline management plans.
The experience developed within this project demonstrates the considerable benefits to scaling-up saltmarsh reinstatement nationally. Restoration could be a significant tool to lower flood and erosion risks across Scotland’s vulnerable shores, now and increasingly in the face of growing climate change risks.
All images © Clare Maynard.