Sabellarids: a hidden danger or an aid to subsea pipelines?

Abstract

Routine surveys of a subsea pipeline off the NE coast of Scotland in 2000 and 2002 revealed the presence of large numbers of encrusting mounds. These were perceived as a potential risk to the integrity of the pipeline and were subject to investigation. The mounds are constructed by sabellarid worms. Individual worms trap sand from turbulent waters, cementing grains to form robust tubes and collectively forming structures up to 0.75 m in diameter, extending over kilometres of pipeline. Growth rates appear to be relatively rapid and the areas occupied increased significantly within the initial period of observation. The mass and surface area of these structures could affect pipeline integrity in two ways: where the pipe is in span a dead load is applied as a direct consequence of the presence of the mounds. In addition, there is an increased lateral live-load as a result of the increase in surface area presented to currents. By contrast, overgrowth of the pipeline may ultimately offer additional protection. This account describes the nature of this novel addition to shallow water pipelines and assesses its likely impact. Observations in 2004 and 2005 indicated substantial reductions in the areas covered by sabellarid colonies and here at least whatever risk they may present has so far proved transitory.

Sabellaria alveolata versus Sabellaria spinulosa Reefs along the Italian Coasts: A New Methodological Proposal to Compare Different Growth Models

“…Sabelliarian reefs can be found along the coasts of all oceans, although, according to the literature, they seem to be concentrated in temperate areas. Sabellaria reefs develop between 0 and 20 m of depth in intertidal or subtidal zones, depending on the species [8][9][10][11][12][13][14][15]. Sabellaria alveolata (Linnaeus 1767) and Sabellaria spinulosa (Leukhart 1849) are the most common species along the European coasts, locally building extensive reefs [5,[8][9][10], such as in Mont Saint-Michel Bay, where it is possible to find the largest dimpled European reef (approximately 60,000 individuals/m 2 [16,17].…”

Sedimentological features of Sabellaria spinulosa biocontructions

“…Sabellariidae reefs and mounds are very widespread, being located along the temperate coastal sectors of all continents (see a complete and recent review in : Fournier, 2013). Sabellaria alveolata and Sabellaria spinulosa (Leukhart, 1849) are the most common species found along the northern European coasts as well as in the Mediterranean Sea: the former, S. alveolata, builds mainly intertidal and subtidal reefs, whereas the latter, S. spinulosa may be found only in subtidal environments as isolated tubes, short-lived crusts and, more rarely, as small reefs (Gruet, 1986;Holt et al, 1998;Nicoletti et al, 2001;Dubois et al, 2003Dubois et al, , 2006Delbono et al, 2003;Braithwaite et al, 2006;La Porta and Nicoletti, 2009). Previous studies have analyzed in detail many and various aspects regarding S. alveolata reefs: i.e.…”

The sedimentary dynamics of Sabellaria alveolata bioconstructions (Ostia, Tyrrhenian Sea, central Italy)

“…Bioconstructions of Sabellariidae polychaetes have also been described from India (Achary 1969(Achary , 1974, Malaysia (Ribero and Polgar 2012), and New Zealand (Ekdale and Lewis 1993). Sabellaria alveolata (Linnaeus 1767) and Sabellaria spinulosa (Leukhart 1849) are the most common species along the coasts of northern Europe, locally building massive reefs (Gruet 1986;Holt et al 1998;Dubois et al 2003;Braithwaite et al 2006).…”