Chaired by Dr Jen Harland, Zooarchaeologist & Trustee of Stromness Museum


Animating Scapa 100  & Orkney Story Stack short films screening

A second chance to see the community animation exploring the quirkier aspects of life in Scapa Flow made with animator Lizzy Hobbs and the films made by Youth Café participants responding to Stromness Museum artefacts.



Below the Flow: marine life on the wrecks and ‘blue carbon’ habitats


International Centre for Island Technology, Heriot Watt University

Scapa Flow has seen some dramatic changes over the centuries, perhaps none so great as the events of the two World Wars. From the perspective of our local marine life, major changes abruptly occurred on that fateful morning in June 1919 when the scuttling of the German High-Fleet began. These wrecks, and subsequent salvaging operations have greatly modified the seabed biological community. Large artificial ‘footprints’ now occupied previously natural seabed habitats but provided a new substrate for the settlement of diverse marine life and created refuges for fish, crustaceans, and octopus. Only a generation after the great scuttling, the marine life of Scapa Flow was again impacted by the wars raging across Europe: new wrecks joined the sunken fleet, none more solemn than the Royal Oak; and the tides of the Flow were radically altered by the construction of the Churchill Barriers.

Prior to WW1 Scapa Flow existed as a natural deep water harbour, with considerable water flowing through and between islands at both the western entrance (Hoy Sound) and across on the east side (Lambs Holm, Glimps Holm, Burray and South Ronaldsay). Prior to the development of barriers to prevent submarines entering Scapa Flow, currents are recorded on charts produced by the Hydrographic Office at levels of 6-7 knots. Since the inclusion of first block ships and then later on the Churchill Barriers, the current flow strength and direction has certainly changed in Scapa Flow, with some areas that were previously high energy, in the present day now being much lower in energy. Consequently, the marine communities will also have adapted and changed in response. It is likely that animals requiring a strong current flow to bring food to them, will have diminished in some areas as the flow regime changed. 

On and around the remaining German wrecks, an interesting array of life has developed over the past 100 years. Some of the marine life is of significance in terms of its conservation status, for example, extensive Horse Mussel (Modiolus modiolus) reefs are living in close proximity to the SMS Karlsruhe, and in association with that habitat a rare example of the Fan mussel (Atrina fragilis). Living amongst the feather stars on the hull of the SMS Dresden those with a sharp eye may encounter the tiny and well-camouflaged Feather Star shrimp (Hippolyte prideauxi). In recent surveys, citizen science divers and local organisations have been undertaking surveys of the salvage sites, and finding several of these sites have been colonised by extensive beds of the habitat-building creatures called Flame Shells (Limaria hians). These colourful and fascinating animals, use long tentacles and secretion of protein based byssus threads to bind together pieces of drifting red seaweed, and broken shells, to fashion nests on the seabed. These nests also act as refuges for a wide variety of other marine animals including scaleworms, spider crabs and the more mobile Curled Octopus (Eledone cirrhosa). 

It is worth considering then, how the presence of the wrecks on the seabed in Scapa Flow now plays such a different role to that for which they were designed. Created as weapons of destruction these wrecks now allow a proliferation of marine life and provide opportunities to divers and scientists to observe and learn more about these organisms. Several of the marine habitat types seen at the wreck sites and the wider Scapa Flow are important in the sequestration of carbon dioxide into storage reservoirs. Collectively, these key habitats and species are referred to as ‘blue carbon’. The importance of blue carbon resources within Scottish inshore waters is becoming increasingly apparent. In Scapa Flow, key blue carbon habitats include maerl beds, kelp forests, reefs made of horse mussels and flame shells, beds of brittlestars, and seagrass meadows. These may help to reduce emissions levels of Green House Gases as photosynthetic algae and seagrass convert carbon to plant material, and filter-feeding animals capture food particles and build into calcium carbonate shells amid complex biogenic habitats. 

And so the importance of the Scapa Flow wrecks continue into the future as we recognise the value of Blue Carbon habitats as mitigation measures to tackle climatic change. Museums will also continue to play a critical role in the coming years: collections, such as those obtained during the Victorian period, allow long-term perspectives necessary to understand decadal-scale forcing agents such as climatic change; and, engagement of the public helps provide a window under the waves, inspiring the next generation of marine stewards.



A Window on Underwater Orkney

PENNY MARTIN – Diver & photographer

Illustrating this presentation with her underwater photography and video footage, Penny will offer a comparison of the marine life that live on the exposed Orkney cliffs with species that have colonised the artificial reefs created by the wrecks and those that live on the muddy sea bottom of Scapa Flow.

Seasearch observer and surveyor courses have helped her identify the surprising variety of colourful cnidarians, squirts, crustaceans, echinoderms, sponges, sea slugs and fishes seen through her lens in Orkney waters. This talk will highlight the different species, their habitat and behaviours, through underwater photography.

3:30-3:55pm Refreshment Break



Title to be announced

DR RICHARD WALKER – Chair, Ghost Fishing UK



The influence of the wrecks on the future management of Scapa Flow

DR GARETH DAVIES – Managing Director, Aquatera Ltd.

5:00-5:25pm QUESTIONS

5:30-5:40pm CLOSING REMARKS from Chair Dr JEN HARLAND

images: Stromness Museum artefacts – Rebecca Marr, Stromness Museum / Archive images – Orkney Library & Archive / Underwater photography- Penny Martin