Marine Biodiversity Data Portal - NI

Correspondence with existing habitats

Habitats Directive Annex I: Reefs

Description: This habitat refers to both shallow subtidal communities and deepwater communities (e.g. CR.HCR.DpSp.PhaAxi) found at 3-50 m deep.

These communities are found on bedrock which is exposed to a range of tidal streams and wave exposures. They are dominated by large, slow growing species such as branching and cup-shaped sponges and cup corals. The branching sponges include species such as Axinella dissimilis, Axinella damicornis, Raspailia and Stelligera species. Other sponge species include Pachymatisma johnstonia, Amphilectus fucorum, Hemimycale columella, Hymedesmia spp., Cliona celata, Polymastia spp., and Tethya citrina and the cup-shaped sponge Axinella infundibuliformis. Large hydroids such as Nemertesia spp., Diphasia spp. and Polyplumaria flabellata may be present together with the bryozoans Pentapora foliacea and Alcyonidium diaphanum. Other fauna includes colonial ascidians Clavelina lepadiformis and Diazona violacea, together with the white cluster anemone Parazoanthus anguicomus and the yellow cluster anemone Parazoanthus axinellae.

In Northern Ireland this broad habitat can be found under a range of environmental conditions including different wave exposures, tidal regimes and depth. Whilst this habitat is widespread, good quality examples can be found at Rathlin Island, The Maidens, Copeland Islands and in Strangford Lough. In Northern Ireland, the CR.HCR.DpSp.PhaAxi biotope is characterised by axinellid sponges on tide swept, circalittoral rock in the North Channel (e.g. Duncan's Bo and Russell Rock).

Associated biotopes:

• CR.HCR.DpSp.PhaAxi - Phakellia ventilabrum and axinellid sponges on deep, wave- exposed circalittoral rock
• CR.HCR.XFa.SpAnVT - Sponges and anemones on vertical, circalittoral bedrock
• CR.HCR.XFa.ByErSp.DysAct - Mixed turf of bryozoans and erect sponges with Dysidea fragilis and Actinothoe sphyrodeta on tide-swept wave exposed circalittoral rock

• EUNIS code: A4.121, A4.139, and A4.1312

Priority species: Axinella damicornis, Antho (Antho) granditoxa, Antho (Jia) brattegardi, Clathria (Clathria) barleei, Clathria (Microciona) elliptichela, Hymedesmia (Hymedesmia) cohesibacilla, Hymedesmia (Hymedesmia) rathlinia, Hymedesmia (Hymedesmia) stellifera, Hymeraphia breeni, Hymerhabdia typica, Lissodendoryx (Ectyodoryx) jenjonesae, Mycale (Mycale) lingua, Plocamiancora arndti, Tethya hibernica, Spongionella pulchella, Alcyonium hibernicum, Parazoanthus axinellae, Parazoanthus anguicomus, Diphasia alata, Diphasia nigra, Lytocarpia myriophyllum, Polyplumaria flabellata, Tamarisca tamarisca, Palinurus elephas

Threats:

• Fisheries: Physical damage from fisheries that deploy bottom gear on rocky seabed areas, such as potting, some fixed nets, trawling and dredging.
• Suspended sediments: Increased levels from fishing activity, dredge disposal or nearby dredging/construction.
• Divers: Physical damage resulting from careless finning and inadequate buoyancy control.
• Angling: Physical damage from entanglement of branching sponges and corals in fishing line.
• Aquaculture: aquaculture activities such as fish farms and mussel farms could cause eutrophication of the seabed and mortality of fragile species such as sponges and anthozoans.
• Increased nutrients: Land run-off and pollution from sewage causes an increase in nutrient levels, potentially leading to algal blooms which can be harmful to marine life (Lan et al., 2024; Beman et al., 2005; Lassus et al., 2016).
• Climate change: Potential for a wide range of possible effects, but significance is not known.

References:

Northen, K.O. & Irving, R.A. (2008) An Atlas of selected marine habitats and species listed on Section 42 of the NERC Act 2006. CCW Contract Science Report No: 833, 72pp. + appendices Editor Nikki Chapman, JNCC
Lan, J., Liu, P., Hu, X., & Zhu, S. (2024). Harmful Algal Blooms in Eutrophic Marine Environments: Causes, Monitoring, and Treatment. Water, 16 (17), 2525. https://doi.org/10.3390/w16172525
Beman, M., Arrigo, K. & Matson, P. (2005). Agricultural runoff fuels large phytoplankton blooms in vulnerable areas of the ocean. Nature. 434. 211-4. 10.1038/nature03370.
Lassus, P., Chomérat, N., Hess, P., Nézan, E. Micro-algues toxiques et nuisibles de l'océan mondial [Toxic and harmful Microalgae of the World] (IOC Manuals and Guides No. 68, Bilinual French/English). Copenhagen, Denmark: International Society for the Study of Harmful Algae/Intergovernmental Oceanographic Commission of UNESCO; 2016:523.