An assessment of the interactions between maritime built heritage and the marine wildlife it supports

Representing an important component of coastal infrastructure in the UK and around the world, historic maritime structures with a traditional block-masonry design (e.g. historic seawalls, harbours, breakwaters, etc.) are valued as heritage assets and for the functional benefits they provide coastal communities. Due to their age and traditional construction, stone-built heritage assets may also provide important, but largely unrecognised, benefits to marine wildlife. At the same time, colonising wildlife may either enhance or retard damaging weathering and erosional processes acting on a structure and/or transform the values associated with heritage sites. As of yet, however, the interrelationships between stone-built heritage and marine wildlife are poorly understood. By adopting an interdisciplinary, multi-method approach that draws on methods and understanding from geomorphology, heritage science, and marine ecology, this thesis investigates the two-way interactions and feedbacks between stone-built heritage and marine wildlife as well as potential opportunities for joint wildlife-heritage conservation. A perception study was used to identify current management practices and attitudes towards marine wildlife by asset managers responsible for the conservation of stone-built heritage assets. Perceived gaps in research relating to wildlife-heritage interactions that were identified in this study were used to inform subsequent fieldwork. A field-block exposure trial was used to evaluate the impacts of seaweed growth on the deterioration of natural-cement-based mortar, a material regularly used in built heritage restoration. Ecology surveys and physical habitat assessments at several locations across the UK were then used to determine the ecological value of heritage assets in comparison to natural rocky cliffs and modern concrete infrastructure. Finally, a novel methodology for identifying priorities for the joint conservation of cultural heritage and marine wildlife was developed, applied, and tested on the Isles of Scilly. Given the broad geographical scope of this research, the results are relevant to other stone-built heritage sites in the UK and further afield. The main findings showed that: (i) attitudes towards marine growth are generally in agreement among practitioners, however concerns exist regarding the impacts of marine wildlife on maintenance regimes, the condition of mortar, and health and safety; (ii) seaweed does not significantly enhance the deterioration of natural cement-based mortar during the first few months of exposure, and instead, may provide broadly bioprotective functions; (iii) historic masonry walls support more diverse ecological communities than modern concrete infrastructure, and in some locations, nearby rocky cliffs; (iv) combined ecological-heritage evaluations allow for the identification of structures with the greatest potential for the joint conservation of built heritage and marine wildlife. Together, these findings have significant implications for the sustainable management of stone-built heritage and marine wildlife. Future work is now needed to develop management strategies designed to deliver joint wildlife-heritage conservation goals in response to growing threats from coastal urbanisation and climate change.

Keywords: Conservation
Built heritage
Biogeomorphology
Marine wildlife
Coastal management
Advisor: Coombes, M
Heather, V