Home Offshore Time Series Geophysical Estuary

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

A third year Oceanography and Marine Biology project conducted by students from the University of Southampton, investigating the physical, chemical and biological properties of the Fal estuary and the surrounding offshore areas.

The aim of this fieldwork is to understand the processes which occur in the transition zone between the coastal sea and the Fal estuary, to collect and interpret a time series measurement in the Fal Estuary, and investigate the substrate, infauna and epifauna of the Fal estuary through habitat mapping. To do this data was sampled and analysed using a wide range of techniques over a series of different sites. Use the navigation bar to view our results and findings.

The Fal Estuary is located on the south coast of Cornwall, UK with an approximate length of 18.1 km. The mouth of the estuary has thick sandstone and mudstone beds (Hughes , 1999) as a result of the drowned river valley dating back to the last Ice Age (Stapleton et al. 1995). A considerable amount of silt is present in the estuary due to sediment deposition and significant anthropogenic influences such as discharge of mining waste (Hughes , 1999).

The Fal estuary is one of the largest estuarine systems in South West England, and as a result it is very important to tourism, conservation and industry development. There are six major tributaries that lead into Carrick Roads (Hughes 1999), the third largest natural harbour in the world, meaning the area is under pressure to be further industrialised (Tuck et al. 2011).

The estuary is generally macrotidal, where tides exhibit a mean spring tidal range of 4.6m, and a mean neap tidal range of 2.2m (UKHO, 2008). Towards Truro the estuary becomes mesotidal with a mean spring tide of 3.5 m (UKHO, 2008).

The Fal Estuary is a designated Special Area of Conservation (SAC) (Hall-Spencer et al. 2008) due to the eelgrass meadows and two resident species of maerl. Both maerl and eelgrass are protected in the area, with maerl species protected under European laws and considered a BAP  (Biodiversity Action Plan). Falmouth is an Area of Outstanding Natural Beauty (AONB) and a SAC due to terrestrial areas also being heavily protected (Langston et al. 2006).

The group sampled through the water column in both the estuary using eulerian and lagrangian measurements as well as offshore . The dominant wind direction is south-westerly. The Falmouth estuary is fed by several rivers, including the Truro, Kennal, Penryn and Carnon; these come together to  form the River Fal which feeds the estuary.

Offshore measurements (26/06/2013)

The measured parameters included current velocity (m/s), temperature (˚C), salinity, chlorophyll (µg/L) and density (kg/m3). Measurements and samples were collected at four different sites using a CTD, ADCP, zooplankton nets, Niskin bottles, and a secchi disk. The locations of the measurements were selected by the group between Blackrock and a regularly sampled station by Masters students of the University of Southampton.

Offshore sample analysis (27/06/2013)

Collected offshore samples were analysed for phytoplankton abundance, zooplankton identification, nutrient concentrations (nitrate, phosphate, and silicate), and dissolved oxygen saturation (%).

Pontoon Time series measurement (28/06/2013)

Time series measurements, on the order of every half an hour, were taken at the Trelissick pontoon, Falmouth. These time series measurements included salinity, temperature, dissolved oxygen, pH, current velocity , current direction and light attenuation using a secchi disk and light meter.

Geophysical (02/07/2013)

Along the Fal estuary, using underwater video footage and  side scan sonar, habitat maps were produced. Changes were observed in flora and fauna, substrate and suspended particle matter throughout the water column at locations along the river. Points of interest were identified from the side scan sonar and used to produce a scientific poster.

Estuary (4/7/2013)

Physical, chemical and biological parameters were sampled at eight stations from the River Truro to the mouth of the Fal estuary. CTD, ADCP , and Niskin bottles were used to collect the relevant data. Samples were analysed in the same manner as the offshore sample analysis

Group Members

Oceanographers:

Sophia Ashby: MSci Oceanography

Calum Fox: MSci Oceanography

Will James: BSc Oceanography

Lucy Lintott: MSci Oceanography

Angelina Smilenova: MSci Oceanography

James Wilkie: Bsc Oceanography with Physical Geography

Marine Biologists:

Jack Harrington: MSci Marine Biology

Jamie Hudson: MSci Marine Biology

Bethan Jones: Bsc Marine Biology with Oceanography

Francesca Trotman: MSci Marine Biology

References

www.ukho.gov.uk, 2011, Date accessed: 1/7/2013

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.

Hughes, S. H. (1999). The ge  ochemical and mineralogical record of the impact of historical mining within estuarine sediments from the upper reaches of the Fal Estuary, Cornwall, UK. International Association of Sedimentologists. 28, 161-168.

Langston, W. J., Chesman, B. S., Burt, G. R., Taylor, M., Covey, R., Cunningham, N, Jonas, P., Hawkins, S. J. (2006). Characterisation of the European Marine Sites in South West England: the Fal and Helford candidate Special Area of Conservation (cSAC). In Marine Biodiversity (pp. 321-333). Springer Netherlands

Stapleton, C., Pethick, J. (1995) The Fal Estuary: Coastal Processes and Conservation. Report to English Nature, Institute of Estuarine and Coastal Studies, Hull.

Tuck, S., Dinwoodie, J., Knowles, H., Benhin, J. (2011). Assessing the environmental impact of anchoring cruise liners in Falmouth Bay. Cruise Sector Challenges. 93-106.

Disclaimer

The views expressed on this website are those of Group 9 on the Falmouth 2013 field course. They are not the opinions of the University of Southampton or the National Oceanographic Center.