Distribution of two species of lugworm (Arenicola) (Annelida: Polychaeta) in South Wales

Abstract

This study demonstrates that the two species of lugworm, previously classified as Arenicola marina occupy distinct zones within sandy beaches around South Wales. Arenicola marina (sensu stricto) or blow lug, is found higher up the shore, tending to be concentrated at mid-tide level, whilst A. defodiens Cadman & Nelson-smith, 1993 or black lug is most numerous at or below mean low water of spring tides and, unlike A. marina in this area, also apparently extends subtidally. Arenicola marina is found in estuaries, unlike A. defodiens, and seems to inhabit slightly less exposed beaches. Degree of sorting, mean and median particle size do not appear to be a significant factor in determining lugworm distributions. Some possible explanations for these observed differences, including differences in burrow depth and salinity tolerance, are discussed.