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University of Southampton Falmouth Field Course 2013    26th June - 6th July 2013    Group 9

2nd July 2013 – Habitat Mapping

Falmouth Tides (UTC): HW 11.45 (1/6/13) 4.20m

LW 06:19 1.50m

HW 12:32 4.10m

LW 18:47 1.60m

True Wind Direction: South Westerly

True Wind Speed: 2ms-1

Introduction

The Fal Estuary is home to two known species of maerl, both of which are protected (Blunden et al. 1997). For this reason conservation programs are in place to protect certain areas of the estuary. Also, habitat mapping of the estuary is important in studying the anthropogenic consequences of developing the estuary further. Habitat mapping and observation of the seabed can be used to locate areas of maerl and therefore study the areas to protect. The maerl in Falmouth Estuary is protected by European law and is a Special Area of Conservation (SAC) (Hall-Spencer et al. 2008). Both species of maerl are Biodiversity Action Plan (BAP) species and are fundamental in forming useful habitats for other species, mainly invertebrates and seaweeds, and increasing biodiversity of the area. These other species live in and amongst the maerl.  The Estuary also contains eelgrass, another protected species. Eelgrass forms part of fragile habitats that are sensitive to environmental change and pollution.

Side scan sonars are useful instruments that collect qualitative estimates of the properties of the seabed lithology using acoustic backscatter (Blackinton et al. 1983). Side scan readings can then be interpreted to produce maps that can be useful in habitat mapping. New developments in digital signal-processing techniques used to interpret side scan sonars mean results can be quantitative where they once were qualitative and geological mapping of the seabed can commence (Johnson et al. 1990).  

Upon boarding MTS Viking vessel seven reference points were chosen up the estuary and the vessel followed these as closely as possible. On this route a side scan sonar was used produced a map of the track and five video points were chosen to aid in habitat mapping of the surveyed area.

Figure G.1: Habitat Mapping Poster (Click to enlarge)

References

Blackinton, J., Hussong, D., & Kosalos, J. (1983). First results from a combination side-scan sonar and sea floor mapping system (SeaMARC II). In Offshore Technology Conference

Blunden, G., Campbell, S. A., Smith, J. R., Guiry, M. D., Hession, C. C., Griffin, R. L. (1997). Chemical and physical characterization of calcified red algal deposits known as maerl. Journal of applied phycology. 9 (1), 11-17.

Hall-Spencer, J. M., Kelly, J., & Maggs, C. A. (2008). Assessment of maerl beds in the OSPAR area and the development of a monitoring program. Prepared for the Department of the Environment, Heritage & Local Government (DEHLG), Ireland. 30pp.

Johnson, H. P., Helferty, M. (1990). The Geological Interpretation of Side-scan Sonar. Reviews of Geophysics. 28 (4), 357-380

Mitchell, A. J., & Collins, K. J. (2004). Understanding the distribution of maerl, a calcareous seaweed, off Dorset, UK. Nishida, T., Kailola, PJ, and Hollinworth, CE (Editors), 65-82.

Geophysical