Submarine Structures in the Mid-Irish Sea and Solan Bank
(2008)
The survey carried out on behalf of JNCC by Cefas had two
objectives:
- To map the extent and condition of an area of potential Methane
Derived Authigenic Carbonate which has formed reef-like structures
in the mid-Irish Sea;
- To map the extent and condition of bedrock and stony reef
around Solan Bank off the north-west coast of
Scotland.
Submarine Structures in the mid-Irish Sea
Survey work within the "Submarine structures in the mid-Irish
Sea" Area of Search took advantage of previous work undertaken by
the SEA6 surveys commissioned by the Department of Trade and
Industry, and gathered additional high resolution acoustic data.
High quality underwater imagery (video and still images) were also
obtained, along with seabed samples, to help interpret the acoustic
data.
"Submarine structures made by leaking
gases" are an Annex I habitat under the
EC Habitats
Directive. These seabed structures are often formed from
Methane Derived Authigenic Carbonate, or MDAC. MDAC occurs where
seabed sediments become bound together by carbonate cement - a
bi-product of the microbial oxidation of methane rising up through
the seabed, forming reef-like structures that provide a unique
habitat for a wide range of marine life. In March 2011 this site
was recommended to Government as
Croker Carbonate Slabs.
Solan Bank
The Area of Search which has now become
Solan Bank pSAC was
found to have extensive areas of bedrock outcrops with high
topography, with linear cliffs rising up to 10 metres from the
surrounding seabed running in ENE-WSW and SE-NW orientations. Away
from the cliffs the substrata ranged from well sorted sands through
to highly fissured bedrock reefs. The majority of reef sites were
characterised by encrusting fauna, in particular encrusting
bryozoans and encrusting corallines in shallower waters. Species of
note were an unidentified cup coral, a sponge which has only
previously been recorded from fishing trawl records and not seen
in situ before (
Oceanapia robusta) and another
species of sponge classified as rare (
Poecillastra
compressa).
That data from this survey was assessed against
established
SAC site selection criteria to determine
whether the Solan Bank Area of Search could contribute to the UK
marine Natura network, and subsequently Solan Bank
was formally advised to Government in December
2011.
Further Reading
- Submarine structures in
the mid-Irish Sea leaflet
- Whomersley, P., Wilson, C., Clements, A., Brown, C., Long, D.,
Leslie, A., Limpenny, D. 2010. Understanding the marine environment
- seabed habitat investigations of Submarine Structures in the
mid-Irish Sea and Solan Bank Area of Search (AoS). JNCC Report 430.
Project Contractors
If you have any further questions about JNCC's offshore survey
work then please contact us.