Investigating the Intertidal Zone

Bringing together researchers in coastal heritage and marine science in response to climate change
An aerial view of Tinside Lido pool, The Hoe in Plymouth, UK
This pilot study in Plymouth Sound demonstrates the value of researchers in coastal heritage working with marine science in response to climate change.
The study established the value of intertidal historic structures as marine habitats: more species were found on historic than contemporary structures, and different species were found on historic structures rather than on natural rock. These findings open a discussion about the value - and use - of historic coastal structures in a future where the intertidal zone will experience changes in sea temperature, heat extremes and energy levels (from waves and swell) that will affect natural and artificial structures alike, which may also change the species and habitats they support.
Plymouth foreshore and lido
Collaboration between building historians and marine scientists has the potential to generate innovative, transdisciplinary research methods that can lead to new insights into the value - and future use - of our coastal heritage as the intertidal zone experiences rapid environmental change. 
Project objectives:
  • Collaborative research: to explore the value of interdisciplinary projects at coastal heritage sites.
  • Document and protect: to document intertidal heritage structures and assess their historical and environmental significance.
  • Public engagement and policy influence: to raise awareness and influence policies for better protection and conservation of coastal heritage.
 
The pilot study focused on the 6-kilometre stretch of foreshore from Tinside to Devil’s Point, from the Hoe to where Royal William Yard juts out into the mouth of the Tamar.
Since the construction of the 1.5 kilometres long Plymouth Breakwater, ‘The Great National Undertaking’ of 1812 – 1844, this stretch of foreshore has had its own distinct natural and human history as the breakwater calmed the waters of the inner Sound, enabling marine and human life to flourish, with amongst other things the rise of leisure sea-swimming. This hybrid maritime history can be read in the numerous little-known structures found the length of the foreshore, often layered upon each other, sometimes forgotten and left to the sea.
Combining the fieldwork skills and methods of historic buildings research with those of marine ecology, researchers worked together at low tide identifying and recording historic structures and their biodiversity. They were able to assess how these structures compare to the adjacent natural habitat and demonstrate the distinctiveness of historic structures as habitats when compared to contemporary structures and materials.

Fresh insights emerge from new ways of working together based on a shared understanding of marine environments as cultural landscapes, landscapes are unique places formed through the interactions of humans and nature over time.

Daniel MaudlinDaniel Maudlin
Professor of History

Researchers in the intertidal zone
 
Rapid biodiversity assessment
In addition to being assessed for their heritage and contemporary value, each historic structure was subjected to a ‘rapid biodiversity assessment’. The biodiversity of adjacent natural rock and contemporary/non-historical structures was also recorded. The results of the combined survey were mapped using GIS:
  • 80 species were recorded overall: 70 on the natural shore and 71 on the historic structures
  • 61 species were common to heritage structures and natural rock, 9 were unique to natural rock, and 10 were unique to historic structures.
Intertidal zone
Intertidal zone
Most of these structures are heavily disturbed, especially during the summer months in peak tourist season. It is, therefore, unsurprising that they support fast-growing species such as green or brown alga, which are the first to grow on uncolonised or disturbed structures. 
In the natural habitats with lower disturbance, other organisms such as crustacea and molluscs have had a chance to outcompete and even graze on the fast-growing species over time, a process known as ecological succession, which may, therefore, be a driving influence on the differences in biological community recorded within the study area.
Research recommendations
Further study is needed to understand the factors influencing the differences in biodiversity and to develop strategies for conserving both biodiversity and historic environments. Initial findings indicate that historic structures can have environmental benefits by attracting diverse species, in addition to their heritage value. Balancing conservation efforts to maintain cultural significance and public use while addressing environmental benefits is crucial. With rising sea levels, future decisions may favor allowing natural weathering over restoration, necessitating revised assessments of the structures' significance. The Plymouth Sound pilot study highlights the benefits of interdisciplinary research in coastal heritage and marine science.
Discover more about the project
If you're interested in learning more about this project and the broader implications of its findings, we invite you to explore the detailed article in the Historic England Research magazine. 
Published in Historic England Research, 24 May 2024
Intertidal zone