Present-day current activity in an inactive canyon-channel system: the Gollum Channel System offshore southwest Ireland.
Verweirder, L.; Van Rooij, D.; Fourie, F.; Langedock, K.; White, M.; Georgiopoulou, A. (2024). Present-day current activity in an inactive canyon-channel system: the Gollum Channel System offshore southwest Ireland., in: Mees, J. et al. Book of abstracts – VLIZ Marine Science Day, 6 March 2024, Oostende. VLIZ Special Publication, 91: pp. 130
In: Mees, J.; Seys, J. (Ed.) (2024). Book of abstracts – VLIZ Marine Science Day, 6 March 2024, Oostende. VLIZ Special Publication, 91. Flanders Marine Institute (VLIZ): Oostende. vii + 130 pp. https://dx.doi.org/10.48470/71, more
In: VLIZ Special Publication. Vlaams Instituut voor de Zee (VLIZ): Oostende. ISSN 1377-0950, more
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Document type: Summary
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Canyon; Channel; Autonomous Underwater Vehicle; Side-scan Sonar; Bathymetry; Bottom Current; Internal Tide |
| Abstract |
The Gollum Channel System is a land-detached large-scale canyon-channel system situated offshore southwest Ireland on the Northeast Atlantic margin. The system is considered to have been inactive since the Last Glacial Maximum (LGM) (Wheeler et al., 2003), but newly acquired geophysical seafloor and shallow subsurface data do suggest recent activity. To test the hypothesis of present-day (in)activity, high-resolution side-scan sonar, photography and bathymetry data were collected using an autonomous underwater vehicle (AUV) in the upper slope (350-1000 m water depth) section of two of the channels. These data are presented alongside current meter data from a mooring station in one of the channels (Verweirder et al., 2021), which were used for quantification and validation of the AUV results. The presence of current ripples on the channel floor indicates that bottom currents acting here are capable of the (re)distribution of sediments. Additionally, some features in the AUV data are interpreted as patches of cold-water corals that depend on nutrient influx as well as a hard enough substrate to grow on, both of which may be promoted by bottom current activity. The current meter data show bottom currents had an average velocity of 15.1 cm/s and reached a maximum of 53.7 cm/s during the measurement period. Therefore, collectively, these datasets allow interpretation of the channel floor features visible within the AUV data with respect to the current regimes they represent, and vice versa. At present, bottom current activity seems prevalent in the channels, while activity from gravity flows has not been observed. |
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