Effects of environmental stresses and climate change on the deterioration of underwater cultural heritage: the THETIDA approach

This research, conducted within the THETIDA project (https://thetida.eu), focuses on identifying threats posed by climate change to underwater cultural heritage sites, with a specific emphasis on the diverse risks – both direct and indirect – that endanger metallic materials, such as anchors, cannons, and structural elements. Notable pilot sites within THETIDA include the US Army WWII PB4Y-1 bomber aircraft Liberator off the coast of Praia de Faro (Portugal), the sunken submarine chaser Equa near La Spezia, and an Ottoman shipwreck in Famagusta bay, Cyprus. These sites offer varied historical backgrounds, construction materials, and biological ecosystems, enabling a comprehensive comparison between sites protected in bays and those in dynamic open ocean environments with currents, sediment dynamics, and biological actions influencing deterioration processes [1]. Being aware of successive reports of the Intergovernmental Panel on Climate Change (IPCC), documenting climate phenomena such as rising sea levels, ocean surface temperature increases, ocean acidification, changes in ocean circulation, extreme wave events and deoxygenation [2], the objectives of the research are to investigate the deterioration effects associated with climate change, assess their evolution across different environments, and develop prediction models. The ultimate goal is to provide practical recommendations for site preservation. The methodology involves studying the sites, historical backgrounds, material compositions, and deterioration characteristics, including physical, chemical, and biological factors of underwater weathering, classification of decay patterns, biocolonisation and biodeterioration characteristics through a multidisciplinary approach. In underwater heritage sites, materials undergo physical, chemical, and biological changes influenced by water, sediment, and living organisms [3, 4]. The study will consider variables such as temperature, salinity, pH, oxygen levels, and the intensity and direction of currents, alongside the depth and location of the site. Mock-up samples will undergo accelerated weathering and autoclave corrosion tests to observe the degradation related to specific environmental parameters. Mock-up samples will also be placed in the real sites to compare the results with the controlled environment aged samples and explore the early stages of deterioration and biocolonisation. This research contributes to understanding the impact of climate change on underwater cultural heritage sites, providing valuable insights for preservation efforts in the face of evolving environmental challenges. Acknowledgement: This research has been funded by European Union’s Horizon Europe research and innovation programme under the THETIDA project (Grant Agreement No. 101095253) (Technologies and methods for improved resilience and sustainable preservation of underwater and coastal cultural heritage to cope with climate change, natural hazards, and environmental pollution).   References [1] THETIDA project websites https://thetida.eu/#/home [2] Gregory et al. (2022). Of time and tide: the complex impacts of climate change on coastal and underwater cultural heritage. Antiquity 96.390: 1396-1411 (https://doi.org/10.15184/aqy.2022.115). [3] Gregory (2009). In situ preservation of marine archaeological sites: Out of sight but not out of mind. In: Situ Conservation of Cultural Heritage: Public, Professionals and Preservation; Richards, V., Mckinnon, J. (Eds) 1-16. [4] Bethencourt et al. (2018). Study of the influence of physical, chemical and biological conditions that influence the deterioration and protection of Underwater Cultural Heritage. Sci. Total Environ. 613: 98-114 (http://dx.doi.org/10.1016/j.scitotenv.2017.09.007).