The Impacts of The Churchill Barriers on the Coastal Environment

Abstract

This research investigated the impact of The Churchill Barriers on the coastal and marine environment through analysis of nearshore and terrestrial cores using geochemical and diatom analyses, ²¹⁰Pb and ¹³⁷Cs dating and field surveying. Analyses of a core taken from near barrier 1 showed that an eutrophic environment dominated throughout the sedimentary sequence. An increase in calcium carbonate, combined with increases in strontium and sodium and a small change in diatom composition, is thought to relate to barrier construction around 1940–1945. A similar pattern is revealed from a core taken near barrier 4 and also from Echna Loch (Burray). On the east side of barrier 4, a large area of sand deposition has occurred as a result of the sheltered environment offered by the barrier. Sediment has been transported northwards by longshore drift and moved onshore from offshore sand bars, forming an extensive sand dune environment. The sediment deposition can be seen to a lesser extent on the east side of the barriers 1, 2 and 3. These results suggest tentatively that barrier formation may have impacted on water flow patterns, and hence algal communities, leading to changes in floral composition. Furthermore, changes in sediment patterns, coastal geomorphology are evident from barrier emplacement.

Key Words:

• Churchill barriers
• geochemistry
• diatoms
• geomorphology
• eutrophication

Acknowledgements

Funding for this work was initially provided by the University of Southampton. The authors thank Dr. Erika Sternberg and Michelle Robinson for undertaking much of the fieldwork, laboratory analyses and production of figures. They also thank Tom Holmes for assisting with the text and figures.