Site details

Porcupine Seabight
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5 stars - Fully protected as a national park or Natura 2000 site by national legislation
MarBEF Deep Sea and Open Ocean Reference Site

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Porcupine Seabight Photo:

Extensive description of site:

The Porcupine Seabight is an amphitheatre-shaped embayment in the continental margin to the south-west of Ireland, measuring roughly 180NM from north to south and 100NM from east to west. It presents gentle slopes along the main north-south axis down to depths of 3000m. but bellow this depth the seabed slopes away quite steeply towards the opening onto the Porcupine Abyssal Plain. The PSB represents a major interruption in the general trend of isobaths of the European continental margin.

Habitats present:

Deep-Sea BedRockSandMudBiohermBenthopelagicWater Column
Continental MarginXXXXXEpi-pelagic X
Abyssal Plain     Mesopelagic X
Seamounts and
Oceanic Islands flanks

Description of fauna and flora:

The biodiversity of the Porcupine Seabight, changes with depth. The continental slope in the mouth of the Porcupine Seabight present holothurians, like Psychropotes longicauda, the crustacean Munidopsis sp., many scaphopods and the asteroids Zoroaster longicauda, Freyella elegans, Hyphalaster inermis and Styracaster spp. There were also sponges, small zoanthids, solitary corals, actiniarians, large natant decapod crustaceans. There were also a few specimens of the benthopelagic holothurian Peniagone diaphana. Several Neolithodes spider crabs were present, as well as the asteroid Hymenaster pellucidus (membranaceus), echinothuriid echinoids and some pagurid crabs. At mid-slope depths in the northeast of the Porcupine Seabight, the invertebrates were dominated by the slimy holothurian Benthogone rosea. At the centre of the Porcupine Seabight, holothurians dominate, like the large synallactid Paelopatides grisea and the elasipodid Benthogone rosea. At the Northern Porcupine Seabight from depths of 4001000m, tehre are several coral mounds with Lophelia reefs.

Habitat description:

Habitats according to EUNIS classification:

A5.3 Deep-sea sand substrates
A5.4 Deep-sea muddy sand
A5.5 Deep-sea muds
A5.52 Communities of bathyal muds
A5.53 Communities of abyssal muds
A5.7 Canyons, channels slope failures and slumps on the continental slope (Canyons, channels, slope failures and slumps but not deep ocean trenches )
A5.71 Active downslope channels
A5.72 Inactive downslope channels
A5.73 Alongslope channels
A5.74 Turbidites and fans
A5.6 Deep-sea bioherms
A5.62 Deep-sea bioherm dominated by Porifera


The access to the area is limited seasonally and an oceanographic vessel is needed and the access to it requires applications to grant awarding agencies.

Available database and website:

Time-series data:
The Porcupine Seabight is visited since 1886 until present time. The SOC and NHM have collections of mega and macrofauna from this region. OMEX results are given in: If the are is extended there are records from the 1980s of the extensive French BIOGAS program in the Northern Bay of Biscay. IFREMER has extensive datasets for this region.

Dataset covering this area:

Commitment and ongoing research:

This is a well studied area having been the subject of considerable study by the Institute of Oceanographic Sciences (now SOC) and a EU MAST programme OMEX. There is considerable biological data for this region in all major categories. There is no funding for the research of this site at this moment.

Additional Information:

Rice Al, Billett Dsm, Thurston Mh, Et Al., 1991.The Institute of Oceanographic Sciences Biology Program in the Porcupine Seabight - Background and General Introduction Journal Of The Marine Biological Association Of The United Kingdom 71 (2): 281-310.
Roberts JM, Long D, Wilson JB, et al., 2003 The cold-water coral Lophelia pertusa (Scleractinia) and enigmatic seabed mounds along the north-east Atlantic margin: are they related? Marine Pollution Bulletin 46 (1): 7-20
Hargreaves PM, 1999.The vertical distribution of micronektonic decapod and mysid crustaceans across the Goban Spur of the Porcupine Seabight Sarsia 84 (1): 1-18
Flach E, Thomsen L, 1998.Do physical and chemical factors structure the macrobenthic community at a continental slope in the NE Atlantic? Hydrobiologia 376: 265-285
Duineveld GCA, Lavaleye MSS, Berghuis EM, et al., 1997. Patterns of benthic fauna and benthic respiration on the Celtic continental margin in relation to the distribution of hytodetritus Internationale Revue Der Gesamten Hydrobiologie 82 (3): 395-424
Gordon JDM, Merrett NR, Bergstad OA, et al., 1996.A comparison of the deep-water demersal fish assemblages of the Rockall Trough and Porcupine Seabight, eastern North Atlantic: Continental slope to rise Journal Of Fish Biology 49: 217-238 Suppl. A
Vincx M, Bett Bj, Dinet A, et al., 1994.Meiobenthos of the Deep Northeast Atlantic Advances In Marine Biology 30: 1-88 1994