Anton Dohrn Seamount and East Rockall Bank (2009)

 
This survey took place between the 1st and 29th of July 2009 and surveyed two areas which at the time were Areas of Search (AoS) for offshore Special Areas of Conservation (SACs). These areas are both now pSACs. Anton Dohrn Seamount located 155km west of the St Kilda archipelago, and East Rockall Bank located 260km west of the St Kilda archipelago. While the team were away on survey they kept an online blog documenting life at sea.
 
Commissioned by JNCC, the surveys were undertaken by the British Geological Survey, University of Plymouth and Marin Mättenik AB.  Its key objective was to acquire high quality acoustic and photographic “ground-truthing” data to enable the distribution, extent and biological characterisation of Annex I reef.

 

Anton Dohrn Seamount

This survey acquired 215 line kilometres of multibeam echosounder data and 10 photographic “ground-truthing” sites.

 

Fish at Anton DohrnGorgonians, Lophelia pertusa and sponges at Anton Dohrn © JNCCSponges and coral on bedrock outrcop at Anton Dohrn © JNCC

 

Although data is still being analysed and interpreted, initial observations revealed the flanks and area immediately adjacent to Anton Dohrn Seamount to comprise predominantly gravel-rich sediment with bedrock outcropping on the steeper sections of the seamount flanks. Interestingly, the parasitic cones surveyed comprised predominantly corals, including large gorgonian species, small bamboo coral, the soft coral Anthomastus sp. and the antipatharian Leiopathes sp. 

 

Click on the image to download a pdf of the map

This video footage shows some of the life that we found living on the parasitic cones and "flies through" some of the multibeam bathymetry data to show the shape of the seafloor around these cones. Multibeam data sourced from SEA 7 (© DTI, 2005), MESH geophysical survey (© Wallis, 2006) and JNCC (© JNCC, 2009). Seabed imagery © JNCC

 

East Rockall Bank

The survey acquired 692 line kilometres of multibeam echosounder and 168 line kilometres of sidescan sonar data within East Rockall Bank.

 

Pencil urchins at East Rockall © JNCCLophelia, sea urchins, anemones, large cup sponge at East Rockall © JNCCSquat lobster, anemones and glass sponge at East Rockall © JNCC

 

17 photographic “ground-truthing” sites were also targeted. Initial observations indicate East Rockall Bank to comprise predominantly gravelly muddy sand on the eastern flank of the Bank with gravel- and sand-rich sediments dominating the crest of the Bank. Significant bedrock reef was encountered along an escarpment located on the eastern flank of Rockall Bank roughly coincident with the 500m bathymetric contour. This laterally extensive feature primarily comprises volcanic bedrock with possible sedimentary bedrock cropping out at sea bed colonised by large stylsaterid hydrocorals and sponges.

 

Click on the image to download a pdf of the mapPreliminary observations and interpretation of the data acquired during the course of this cruise suggest that several sites at both AoS may fit the definition of Annex I reef under the EC Habitats Directive. Once reporting is completed (end March 2010), the sites will undergo assessment against site selection criteria for possible consideration as SACs.

 

The cruise report available below summarises operations and initial observations onboard the M/V Franklin during cruise 2009/03-JNCC on behalf of JNCC. 

 

Further Reading

  • Stewart, H., Davies, J., Long, D., Strömberg, H. & Hitchen, K.  2009.  JNCC Offshore Natura Survey: Anton Dohrn Seamount and East Rockall Bank.  2009/03-JNCC Cruise Report. Report No. CR/09/113.

 

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