Serpula vermicularis is a sedesedentary polychaete that secretes a calcareous tube are while common and widespread around Ireland and Great Britain, however under certain circumstances they can form biogenic reefs. Typically the species occurs as individual tubes as shown.
What are biogenic reefs and how are Serpula reefs formed?
Bogenic reefs are made up of hard material created by living things. Serpula reefs typically occur when the larvae settle on existing tubes or dead tubes lying on the sea floor and as this occurs over and over the reef grows in size which can reach up to 2m. Reefs typically occur in soft muddy habitats but grow predominately on rocks in Ardbear Lough and Kilkieran Bay.
Where are they found?
Serpula vermicularis reefs have been recorded from just 7 locations: Blacksod Bay, Co Mayo; Kilkieran Bay, Ardbear Lough (Bosence, 1973), and Killary Harbour (Minchin, 1987), Co Galway; a lagoon near Taranto in Italy (Mastrangelo & Passeri, 1975); and Loch Creran (Moore et al., 1998) and Loch Teacuis (Dodd et al., 2009) in Scotland.
Threats to Serpula reefs
Serpula reefs are vulnerable to a number of threats found in shelter bays including those common to most marine species, poor water quality, eutrophication from freshwater run off and the impact of fish farms. However the chief threat is the impact of bottom trawled fishing gear, deployment of anchors by dive boats and other activities that damage the sea bed in areas where reefs are present. To view the impact on the reefs at Killary Harbour you can view a video of the reefs in 2018 and 2012 and compare for yourself the impact.
References & Further reading
Bosence, D. (1973). Recent serpulid reefs, Connemara Eire. Nature, 40(1), 242.
Dodd, J., Baxter, L., & Hughes, D. J. (2009). Mapping serpula vermicularis (polychaeta: Serpulidae) aggregations in loch teacuis, western scotland, a new record. Marine Biology Research, 5(2), 200–205. https://doi.org/10.1080/17451000802345858
Mastrangelo, P., & Passeri, I. (1975). Sedimenti calcareo-argillosi e biolotiti a serpulidi nel Mar Piccolo di Taranto. Bollettino Della Societa Geologica Italiana, 94, 2019–2046.
Minchin, D. (1987). Serpula vermicularis L. (Polychaeta: Serpulidae) Reef Communities from the West Coast of. In Irish Naturalists’ Journal Ltd. Ir. Nat. J (Vol. 22, Issue 7).
Moore, C. G., Saunders, G. R., & Harries, D. B. (1998). The status and ecology of reefs of Serpula vermicularis L. (Polychaeta: Serpulidae) in Scotland.