The Isles of Scilly Biodiversity Audit 2008 - Cornwall Wildlife Trust

2.2.1.9 Annelida - Marine WormsOverviewMarine worms are a diverse group yet most areroughly similar in appearance and are often hard toidentify without specialist knowledge or laboratoryanalysis. For this reason they are generally underrecordedwith little known about their conservationconcerns.Soft sediments support rich communities of worms;they are also found in rocky crevices, on hardsurfaces, in kelp holdfasts and free-swimming. True(segmented) worms are called Annelids but there arealso several groups of worm-like creatures which arefound in the marine environment, these are covered inSection 2.2.1.26 on lesser-studied phyla.In the marine environment worms play a criticalrole in breaking down organic matter, aerating andstructuring sediment. They are the main prey of manyspecies of fish and birds.Important AreasThe sediment shores and sand flats in the Isles ofScilly are important for marine worms. Some areas aredominated by the lugworm Arenicola marina, whosepresence is revealed by casts in the sand producedduring feeding (Warwick, 2004). Other areas ofsediment are dominated by sand mason worms Laniceconchigela, sedentary filter feeders which live in tubeswhich they creates out of sand grains and mucus. Theimportance of St Martin’s flats for worms and otherinfauna is recognised and the area is a designated SSSI.Great Pool, a brackish lagoon on Bryher supports aspecies of Arenicola (Bamber et al, 2001).Conservation ImportanceThere are no worms in Scilly which are BAP species.In general worms are a very under-recorded group.In a 1971 expedition to Scilly, Harris found 17 rare ornewly recorded polychaete worm species for Britain,one of which was new to science. They also found 10species of Spirobis (spiral worm) of which 2 were newto science.In a survey of the faunal communities on theundersides of intertidal boulders in Scilly in 1990,Foster-Smith found that spirobid worms were themost important group in terms of abundance. Sabellavariabilis, a small fan worm very rarely recorded inBritain, is abundant in Scilly (English Nature 1994)Trends and IssuesResearchA number of papers on worms and their relatives havebeen published in the series on the marine flora andfauna of the Isles of Scilly in the Journal of NaturalHistory. Harris published an inventory of the marinePolychaetes of the Isles of Scilly in 1972.PollutionSome worms process large amounts of sediment asthey feed and are vulnerable to accumulation of heavymetals or organic compounds in their tissues. Wormscan also assist in the breakdown of pollution. Intertidalspecies are at risk during oil spill incidents.Peacock worm Sabella pavonina. Photo: Angela GallIsles of Scilly biodiversity audit Page 22