When History meets Biology: Shipwrecks as Ecological Hotspots

few kilometres of the Grand Harbour, however, there are submerged sites all around the islands. World War I vessels lost to mines include the HMS Russel (115m), HMS Nasturtium (67m) and HMY Aegusa (125m) which tragically sunk in the same minefield on the same day in 1916. Submarines that met the same fate in minefields off Valletta include HMS Urge (108m) and HMS Olympus (115m), both sinking in 1942. Other vessels sunk by mines in World War II include HMS Southwold (69m), ORP Kujawiak L72 (98m) and Schnellboot S-31 (66m) which sunk after striking its own mine. Aircraft, on the other hand, were shot down by flak or during dogfights, crashing into the sea, such as the JU88 North (56m) and JU88 South (110m), whilst others suffered engine failures, resulting in their ditching at sea. These include the B-24 Liberator (55m), Douglas A-1 Skyraider (96m) and Fairey Swordfish (70m).

The sheer number of vessels sunk, their variety in sizes, compositions, and depth at which they lie, compounded with the time spent underwater, has allowed marine life the time to establish themselves and flourish into large complex communities. This article will focus on two sites, HMS Nasturtium and HMS Olympus, both related to Malta’s wartime legacy, and both known to be hosts to varied and protected marine life. The intention is to highlight a specific type of marine life present on these sites, and how a closer examination of these ecological hotpots can inform decision making when it comes to management strategies.

Biodiversity data generation on wreck sites

HMS Nasturtium was one of 36 Arabis-class sloops, built to counter the growing threat of underwater mines and submarines during World War I. The sloop was launched in 1915 and was based in Malta. In April 1916, Nasturtium was searching for mines laid by the German submarine U-73, and whilst located approximately 10km off the coast of Malta, Nasturtium struck a mine on the starboard side. The resulting explosion caused the sloop to slowly flood, listing it to port, and whilst several attempts were made to tow the vessel back to shore, HMS Nasturtium eventually sunk.

Today, the wreck lies approximately 12 nautical miles off the coast of Valletta and rests on a sandy seabed at a depth of 67 metres. The site was first discovered by fishermen and is in a good state of preservation, heavily colonised by sponges and other marine life. The density of sponges on the site, often noted by visiting divers, resulted in the decision to carry out a sampling experiment to begin quantifying and qualifying the marine life present on the site. To this end, Heritage Malta applied for a sampling permit from the Environmental Resources Authority in early 2021, to conclusively identify the species present. This was done through technical divers, where small fragments of sponge were collected. These were fixed and preserved, and later analysed by taxonomic specialists from the Centre for Advanced Studies of Blanes, research institute of the Spanish National Research Council. The dominant species identified from the collected sample was identified is Aplysina cavernicola. This is a species of sponge that is native to the western Mediterranean, where it typically grows in caves, with its base adhering to the hard surface and colonies of small fingerlike protrusions extending from it (World Register of Marine Species). In this case,

HMS Nasturtium is acting as a substitute to the hard rock surface, with colonies of the sponge clearly thriving on the site. Of note, this species is protected on a national level through Schedule VI of the Flora, Fauna, and Natural Habitats Protection Regulation, and on an international scale through the Barcelona Convention Annex II and Bern Convention Appendix II.

The information gathered through such exercises allows heritage managers to gain a deeper understanding of how historic wrecks are affecting the surrounding environment, and how in turn, that environment is impacting the wreck. In addition, the legislative protection provided for these marine species act as an additional level of protection for UCH sites and vice-versa. No further sampling is planned, as high-resolution images and videos are now being used to quantify the presence of these species.

HMS Olympus is a British Royal Navy submarine of World War II that struck a mine and sunk approximately 11km off the coast of Valletta. HMS Olympus was an O-class submarine that was completed in 1930. The submarine spent the inter-war period patrolling the South China Sea, and with the outbreak of

World War II joined the Mediterranean Fleet. HMS Olympus was mainly involved in the socalled ‘magic carpet service’ that transported troops and cargo to-and-from Malta, a task that was becoming increasingly more dangerous as Axis forces intensified efforts to neutralise Malta (Gambin 2015). In May 1942, HMS Olympus arrived in Malta with much needed supplies, and as the submarine was preparing to depart the island, it was decided that surviving crew members from the submarines P36 and P39 – both sunk in the harbour in an air raid – would depart with HMS Olympus (Gambin 2015). When HMS Olympus struck a mine and sunk, the loss of 89 servicemen would make this the worst submarine disaster in the Royal Navy history.

The wreck site of HMS Olympus was discovered in 2011 through the ongoing Malta Shipwreck Survey Project, a collaboration between the University of Malta and the Superintendence of Cultural Heritage. The submarine lies upright on a sandy seabed at a depth of 115 metres, making it the deepest site currently open to the diving public. The wreck is almost fully intact, except for the damage on the starboard side where the mine had struck it. The open hatch on the conning tower attests to attempts made by the crew to escape the sinking submarine, and in 2017 for the 75th anniversary of the loss of HMS Olympus, a University of Malta dive team placed a memorial plaque on the submarine to commemorate those who lost their lives that day.

The marine ecological importance of HMS Olympus lies in the growth of black coral on the site. Research into Black Coral – Antipathella subpinnata – in the Mediterranean is scarce; however, recent studies have highlighted how Malta hosts one of six cold-water coral provinces known in the Mediterranean. The species grows in depths up to 600 metres on hard surfaces such as rocks and can grow up to 1.5 metres in height. This allows the Black Coral to act as a refuge for other species, becoming hotspots of marine biodiversity (IUCN). The species has a slow growth rate and longevity, and is also protected on a national and international level, which is listed as ‘Near Threatened’ on the International Union for Conservation of Nature Red List for the Mediterranean.

These two examples constitute the very beginnings of Heritage Malta’s efforts to understand the biological complexity of historic shipwreck and aircraft sites, which have inspired the launch of the WreckLife project. Among the several objectives of the WreckLife project is the use of legacy data along with the generation of new data. Data generated from past archaeological surveys, including remote sensing surveys and visual surveys, either carried out by divers or remote operated vehicles (ROVs), are understood as legacy data. These are being analysed to quantify and qualify marine life on shipwreck sites, and to determine whether changes over time can be noted. New data sets will be gathered through the UCHU’s annual surveys by technical divers. Using state-of-the-art technologies, 3D data, high-resolution imagery, and videos, as well as footage are gathered at night and in 360°. These include the generation of 3D models, which from an archaeological perspective, are used as baseline models from which wreck site preservation and condition can be monitored. From a marine ecological perspective, these 3D models can be used to set up an electronic ecosystem that is site specific.

Conclusion

Gaining an in-depth understanding of the biodiversity and communities present on Malta’s deep water historical sites will aid in the understanding of how best to preserve underwater cultural sites for generations to come. Creating this base-line dataset and combining this knowledge with ongoing surveys can in turn help forecast how variations in the environment, attributed to climate change, will affect historical wrecks and the ecosystems built around them. This interdisciplinary approach, combining archaeology, heritage management and marine ecology will pave the way for future initiatives and projects centred around identifying and finding links between local and distant populations. This will further strengthen the importance of conserving and protecting underwater cultural heritage as both cultural and ecological assets.

The authors would like to thank Dr Julian Evans and Professor Joseph A. Borg for sharing their knowledge and help with getting these studies off the ground.

Bibliography

Gambin, T., 2003, ‘The Maritime Heritage of Malta’, Transactions on the Built Environment, 65: 4-15 Gambin, T., 2015, ‘HMS Olympus: A tale of tragedy and heroics’, Malta University Historical Society, pp. 111-140 Aplysina cavernicola, World Register of Marine Species, available at: https://www.marinespecies.org/aphia. php?p=taxdetails&id=133913 (accessed on 02.03.23) Antipathella subpinnata, IUCN, Available at: http:// www.iucn.it/scheda.php?id=-515800724 [accessed on 02.03.23]

Fiona Vella