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Introduction


An investigation was undertaken by 2nd year Marine Biologists and Oceanographers from the University of Southampton in the Fal estuary and coastal offshore waters. This was completed from Monday 22nd June to Friday 3rd July 2015, with the field course now running in its 9th year.


The aim of this study is to investigate and compile data including chemical, physical, biological and geophysical parameters, to aid understanding of the processes and interactions occurring in the Fal estuary. Data was collected during estuarine, coastal and offshore boat trips as well as from the King Harry Pontoon. Data was collected from 4 main surveys:


- A coastal geophysics survey on board MTS XPLORER looking at the sea floor substrates within St Mawes harbour, using a side scan sonar towfish along fixed transects.

- An offshore survey on board the RV Callista looking at the water column structure, nutrients, zooplankton and phytoplankton communities.

- An estuarine survey  in the Fal on board RV Bill Conway to investigate the physical, biological and chemical properties of the estuarine system.

- A pontoon survey  on the Fal on the King Harry Pontoon to investigate all of the physical properties around the pontoon and create a full day time series.



Falmouth Field Course 2015 - Group 3

The views and opinions expressed on this page are those of Group 3 and do not represent the views of the University of Southampton, the National Oceanography Centre or Falmouth Marine School.


Figure 2.1: Map of Cornwall (Project Exeter, 2015)

Figure 2.2: Map of Fal estuary (Project Exeter, 2015)

The outer basin is known as Carrick roads and is characterised by deep water channels, with a maximum depth of 34 metres and containing the main water body of approximately 80% of the water volume of the Fal (Hughes, 1999). Within the inner tidal tributaries there are 6 main tributaries and 28 minor creeks and rivers. The tidal range varies with a maximum spring tide in Falmouth of 5.3 metres (macrotidal) (Stapleton and Pethick, 1996) and in Truro of 3.5 metres (mesotidal) (Project Exeter, 2015).


Species that live within the Fal have faced pressures from mining waste and disasters, such as the Wheal Jane Disaster that contaminated the Fal with the heavy metal tin, in January 1992 (Younger et al., 2005). Although mining has ended in Cornwall, residual pollutants still remain within the sediment. Other pollutants have also been deposited in sediments such as TBTs (Tributyl tin) which was used as an anti-fouling paint on ship hulls. This is thought to be responsible for imposex in gastropods (Iguchi et al., 2007) in the fal, especially in the dogwhelks (Nucella lapillus) (Bryan et at., 1987).



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The estuary is a Special Area of Conservation (SAC) (Figure 2.3) as designated by the European Marine Sites (EMS) under the habitats directive. SACs are areas supporting rare, endangered or threatened species (Natural England, 2004). The Fal estuary is one of the best sites in Europe for marine wildlife due to the presence of two species of maerl (Rostron 1987), Lithothamnion coralloides and Phymatolithon calcareum found in an area between St Just and St Mawes. Both these species are a Biodiversity Action Plan (BAP) species as they are uncommon in England and provide a unique habitat for a large number of species (Seasearch, 2012). The extent and community composition of the maerl beds has only recently been described by Seasearch (2012). Maerl is a calcareous algae which acts as a nursery bed for many commercially important fish and shellfish. It is incredibly slow-growing at approximately 1mm per year. As a result of its slow growth, maerl is at particular risk from anthropogenic activities, such as anchoring, dredging and trawling as well as changes in climate, pathogens and storm damage (Birkette, 1998).


Although extremely important for biodiversity, maerl is not the only important species within the Fal. Eelgrass (Zostera marina), a flowering plant, is also a habitat forming species providing shelter for small organism and also acting as a nursery ground. Although not protected under Biodiversity Action Plan (BAP), it is covered by the Habitat Action Plan (HAP) (Tyler-Walters, 2008).




Background on The Fal Estuary

The Fal estuary is located on the southwest coast of England, West Cornwall. It is the 3rd largest natural harbour in the world (Cornwall Rivers Project, 2006). The Fal estuary is a ria (a drowned river valley) (Cornwall wildlife trust, 2015), which formed in response to the Holocene sea-level rise (Pirrie et al., 2003) approximately 12000 years ago (Nesbet, 1990).


Falmouth is an incredibly successful region of Cornwall previously relying economically on its commercial port and fisheries. It also prospered from the nearby heavy metal mining industry, which dates back to the early Bronze Age approximately 4000 years ago (Pirrie et al., 1995). However in recent years there has been a switch from these major industries to tourism,which has rapidly become a leading force for development in the area. Fisheries have continued in the Fal with important species such as the native oyster (Ostrea edulis), seabass (Dicentrarchus labrax), cockles (Cardiidae sp.) and scallops (Pectinidae) being harvested, as well as aquaculture farming for the pacific oyster (Crassostrea gigas) and common mussel (Mytilus edulis). These industries continue the economic importance of fisheries in the Fal (Port of Falmouth development initiative, 2009), despite the introduction of tourism.


The Fal is a large estuary at approximately 18km in length, starting in Truro and ending in between Pendennis point and St Anthony Head in Falmouth, where it enters the English Channel (Cornwall guide, 2015).It is usually subdivided into two areas, the inner tidal tributaries and the outer basin.

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References


Birkett, D. Maggs, C. and Dring, M. (1998). An overview of dynamics and sensitivity characteristics for conservation management of marine SACs. Report. Available online: http://www.researchgate.net/profile/Matthew_Dring/publication/242736827_An_overview_of_dynamics_and_sensitivity_characteristics_f or_conservation_management_of_marine_SACs/links/02e7e52ba083f13d1e000000.pdf. Pp: 56-59. Date accessed: 28/06/2015


Bryan, G. Gibbs, P, Hummerstone, L. and Burt, G. (1987). Copper, zinc and organotin as long-term factors governing the distribution of organisms in the Fal estuary in Southwest England. Estuaries. Vol.10. Pp: 206.


Cornwall guide, (2015). The River Fal. Webpage. Available online: http://www.cornwalls.co.uk/Falmouth/fal_river/htm. Date accessed: 27/06/2015


Cornwall Rivers Project, (2006). Geography, Fal and Tresillian. Webpage. Available online: http://www.cornwallriversproject.org.uk/geography/fal.htm.  Date accessed: 23/06/2015


Cornwall wildlife trust, (2015). Fal-Ruan Estuary Nature Reserve. Webpage. Available online: http://www.cornwallwildlifetrust.org.uk/nature_reserves/where_to_find_the_nature_reserves_1/Cornwall_Wildlife_Trust_Fal_Ruan_Estuary _nature_reserve_Roseland. Date accessed: 27/06/2015


Hughes, S. (1999). The geochemical and mineralogical record of the impact of historical mining within estuarine sediments from the upper reaches of Fal Estuary, Cornwall, UK. Fluvial sedimentology. Published by The International Association of Sedimentologists. Vol. 28. Pp: 161-162.


Iguchi, T. Katsu, Y. Horiguchi, T. Watanabe, H. Blumberg, B. and Ohta, Y. (2007). Endocrine distrupting organotin compounds are potent inducers of imposex in gastropods and adipogenesis in vertebrates. Molecular and cellular toxicology. Vol. 3 Pp: 1.


Natural England, (2004). Fal and Helford SAC Management Scheme. Report.  Pp: 1-3.


Nesbet, E. (1990). The end of the ice age. Journal: Canadian Journal of Earth Sciences. Vol. 32(10). Pp: 1. Date accessed: 27/06/2015)


Pirrie, D. Camm, G. Sear, L. Hughes, S. (1995). Mineralogical and geochemical signature of mine waste contamination, Tresillian river, Fal estuary, Cornwall, UK. Environmental geology. Vol. 29. Pp: 1.


Pirrie, D. Power, M. Rollinson, G. Camm, S. Hughes, S. Butcher, A. and Hughes, P. (2003). The spatial distribution and source of arsenic, copper, tin and zinc within the surface sediments of the Fal Estuary, Cornwall, UK. Sedimentology. Vol.50. Pp: 580.


Projects Exeter, (2015). Location of the Fal estuary. Webpage. Available online: https://projects.exeter.ac.uk/geomincentre/estuary/Main/loc.htm.  Date accessed: 24/06/2015


Rostron, D. (1987). Surveys of harbours, rias and estuaries in Southern Britain: Falmouth. Report published by Pembroke: Oil Pollution Research Unit. FSC Report, No. FSC/OPRU/17/87.


Royal Haskoning, (2009). Commercial fisheries and shellfisheries. Report: Port of Falmouth development initiative. Pp: 249-251.


Seasearch, (2012). Maerl in Cornwall, 2012 survey report. Report. Available online: http://www.seasearch.org.uk/downloads/Cornwall%20maerl%202012%20web.pdf. Pp: 1-3. Date accessed: 28/06/2015


Stapleton, C. and Pethick, J. (1996). The Fal estuary: Coastal Processes and Conservation. Report: Institute of Estuarine and Coastal Studies. University of Hull, English nature, Peterborough, UK.


Tyler-Walters, H. (2008). Zostera marina. Common eelgrass. Marine Life Information Network Biology and Sensitivity, Marine biological association of the United Kingdom. Webpage. Available online: http://www.marlin.ac.uk/speciesfullreview.php?speciesID=4600. Date accessed: 28/06/2015


Younger, P. Coulton, R. and Froggatt, E. (2005). The contribution of science to risk-based decision-making: lessons from the development of full-scale treatment measures for acidic mine waters at Wheal Jane, UK. Science of the Total Environment. Vol. 338. Pp:  137.




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The analysed data, observations and preliminary findings are all collated onto this website to display details on each of the survey sites as well as including information on biological and chemical laboratory analysis of collected samples. The combined data and investigation from each of the sites together will allow The Fal to be seen as one entity.



Contents

Figure 1.1 & 1.2: Tide charts for Falmouth from 22nd June to the 4th July 2015.

Figure 2.3: map to show SAC areas and areas of interest in the Fal.