GROUP
Plymouth Field Course 2019
4
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GEOPHYSICS
Geophysical Habitat Mapping
In order to map the benthic habitats in Plymouth Sound, we chartered a public vessel, Sonardyne, and employed a combination of side-scan SONAR and video recordings. Our group mapped the substrate at Renney Rocks in Heybrook Bay, as this area had not been surveyed previously and was located near unique geological formations. At the sample site, 4 parallel 1km tracklines were produced for Sonardyne to follow for the side-scan SONAR survey. The image produced by the side-scan towfish revealed a mostly rocky substrate with some larger submerged rock formations and sandy patches being small and sporadic. In order to provide some ground truthing of this imaging, a video feed was relayed to the vessel, which confirmed the nature of the substrate. This video recording also revealed the presence of kelp beds and algal turfs on the rock, inhabited by starfish, sea cucumbers, sponges and many other animals. This provided much more information about the habitat than the substrate alone. The findings from this survey were compiled into a poster, which provides much greater detail into the background of the area, the methodology and the results of the survey.
Click on the poster below to view full resolution:
3D Contour Map:
Click on map to enlarge
The figure above shows a 3D contour plot created using Surfer 8, using the X (Eastings), Y (Northings) and Z (Depth) coordinates from the sidescan sonar geophysical survey. The map shows a green region of uniform depth, with occasional rocky features or dips. Approaching the opposite side of the plot, the seafloor is raised with a prominent ridge like-feature, suggesting the habitat provides a rocky settlement surface for animal and plant life.