INFOMAR seafloor survey off the Dingle Peninsula

Google Earth Approx area surveyedINFOMAR is an ambitious joint venture between the Geological Survey of Ireland and the Marine Institute to map Ireland’s most productive and commercially valuable inshore waters. Covering some 125,000 square kilometres of underwater territory, INFOMAR(INtegrated Mapping FOr the Sustainable Development of Ireland’s MARine Resource) will produce integrated mapping products covering the physical, chemical and biological features of the seabed. The INFOMAR programme began last summer with surveys of valuable fishing and fish farming areas in Bantry Bay, Dunmanus Bays and fish spawning areas off the South West Coast.

First Leg of 2007 Survey Complete

The first leg of the 2007 survey was completed on May 15th, having covered an area of 2,899 square kilometres in water depths between 26 and 203 m, off the Dingle Peninsula since it began on April 17th.  In near perfect sea conditions, the R.V. Celtic Exploreraccurately mapped the depth and seafloor characteristics of an area similar in size to County Limerick (2,686 square km) and more than twice the size of County Dublin (921 square km)  This work follows on from the Irish National Seabed Survey and the work that was started in 2006 under the INFOMAR programme.

Biologically Sensitive Area Surveyed

The area covered is within the “Biologically Sensitive Area” (BSA), designated by the EU Commission in 2003 following successful lobbying by the Irish government, fisheries scientists and industry.  As such, fishing effort in the area is restricted to a pre-specified effort as a form of protection.  To further investigate the important conservation and fisheries value in the BSA, INFOMAR has targeted it for exploration of the seafloor marine resources using high resolution multibeam sonar, measuring gravity and magnetic variations, and recovering grab samples for biological, chemical and geological analysis.

In the shallower inland waters to the south east of the area surveyed, the sea floor is found to consist mainly of bedrock gullies infilled with soft sediments.  The eastern part of the survey area is characterised by sands and to the south west, coarse shelly sands.  In the north east a large area of sand waves has been found, possibly composed of till material deposited during the last glaciation.  These sand waves are overlain by shelly sand ribbons.  The direction of the crests of the sand waves (aligned northeast to southwest) and their asymmetrical shape with scarp (front) slopes facing the northwest, indicates that the dominant current is to the northwest.

The multibeam sonar survey has identified five distinct seafloor regions within the survey area.  Grab samples were collected from 49 stations across these regions to examine the biological community they support.  Initial inspection shows a good collection of worms, tube forming animals, echinoderm (urchin) species, cup corals and molluscs.  The samples will be analysed in more detail in Galway - Mayo Institute of Technology, to better understand the ecology of the BSA.

The survey was conducted to the standards of the International Hydrographic Organisation (S44 Order 2) and the data will be used to update navigation charts of the area.  Six possible wrecks were identified during the survey. These have yet to be compared with known wreck lists of the area.

Core Samples Taken from Outer Galway Bay

For the first time, the INFOMAR programme also collected 9 vibrocore samples of the sea floor in outer Galway Bay.  Five of these cores are from an area where the National University of Ireland, Galway (NUIG) are investigating the effects of groundwater runoff from the Burren on sediment input and deposition rates of the Bay.

From here the offshore component of the INFOMAR programme will be moving on to map areas of the Kish Bank off Dublin, Waterford Harbour, and continue work from 2006 in Bantry Bay and focus on Galway Bay.