Falmouth 2015 - Group 2 A Study on the Fal Estuary

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Introduction to Falmouth

The Fal estuary, located in the South-West of England, is the largest in the country. In fact, the estuary is considered to be the third largest natural harbour in the world, reaching over 24.8km2 with 6 tributaries, such as the river Truro and Penryn, and 28 other minor river inputs into the upper estuary leading to the main body, called Carricks Roads (1). Cornwall has a submergent coastline and as a result, many of the estuaries in the area are rias. A ria is a drowned river valley, formed from the melting of glaciers after the last ice age. Although, the Fal estuary is unique in that it has a deep channel running through Carricks Roads, up to 34m deep near the top end of the estuary, which is much deeper than most surrounding estuaries (2).


However, not only does the Fal estuary have unique topography, it is also one of the first marine SACs (Special Area of Conservation) due to its great biological diversity. There are a wide variety of marine habitats throughout the estuary, such as salt marshes, mud flats and even eel grass beds in the Helford. These eel grass beds are an SSSI (Site of Special Scientific Interest) and sustain a wide variety of life and used as nursery grounds for many fish species (3). Not only this, but Carrick Roads is also home to the largest live maerl bed in the UK. Maerl is a very rare and slow growing species of red coralline algae and is greatly protected. The nodules of maerl create a complex benthos in which many species seek shelter (4).

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Research


Research was conducted throughout the estuary and offshore, from June 22nd to July 4th 2015, to create a comprehensive database about the chemistry, biology, physics and geophysics of the area.


The estuary was surveyed using the Bill Conway, using several methods to observe chemical, biological and physical changes down the estuary and vertically through the water column. The King Harry pontoon was also used to comprise a time series of similar parameters to those collected on the Bill Conway. Eel grass beds around Durgan in the Helford were investigated by the MTS Xplorer, using a side scanner and video camera to study the topography of the area and the growth of a newly planted sea grass bed in the area. Finally, the RV Callista was used in offshore work for a depth profile time series. Detail of the methods used and initial findings of these surveys can be found on the website.

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About the Team


The research team consisted of 10 undergraduate and exchange students from the University of Southampton studying Marine Biology, Oceanography or Meteorology, click here for more information.

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References


  1. Projects.exeter.ac.uk, (2015). Location. [online] Available at: https://projects.exeter.ac.uk/geomincentre/estuary/Main/loc.htm [Accessed 29 Jun. 2015].
  2. Destination-cornwall.co.uk, (2015). The Fal Estuary and Area. [online]
    Available at: http://www.destination-cornwall.co.uk/portfal.htm [Accessed 29 Jun. 2015].
  3. Jncc.defra.gov.uk, (2015). Fal and Helford - Special Area of Conservation - SAC - Habitats Directive. [online]
    Available at: http://jncc.defra.gov.uk/protectedsites/sacselection/sac.asp?EUCode=UK0013112 [Accessed 28 Jun. 2015].
  4. Deeble, M. and Stone, V. (1985). A port that could threaten marine life in England's Fal Estuary. Oryx, 19(02), p.74.

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Figure 1. Location of the estuary on the south- west coast of Cornwall

Figure 2. Showing the extent of the SAC that involves the Fal estuary



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