A review of the occurrence and ecology of dense populations of Ditrupa arietina (Polychaeta: Serpulidae)

Abstract

Hartley, J.P. 2014. A review of the occurrence and ecology of dense populations of Ditrupa arietina (Polychaeta: Serpulidae). Memoirs of Museum Victoria 71: 85-95.Dense populations of the free-living serpulid Ditrupa arietina were first recorded to the west and north of the Shetland Isles in the 1920s and have since been reported from the Celtic and North Seas, the Armorican shelf, the Mediterranean and the Azores. These dense populations (of many thousands per square metre) numerically dominate the benthic fauna, and the tubes provide sites of attachment for a range of other species. Vacated tubes are also occupied by other animals, and tube fragments can contribute significantly to biogenic carbonate sediments, both Recent and fossil. Dense Ditrupa populations have been the subject of detailed autecological research over the last 15 years, but in spite of the apparent ecological importance of the species, it is not reflected in the European Nature Information System (EUNIS) or other North-east (NE) Atlantic habitat classifications. This paper provides a synthesis of the environmental conditions where high densities of Ditrupa have been found, with new data from seabed samples and photos. Ditrupa appears to occupy different habitats in the NE Atlantic and the Mediterranean, and studies of its morphology and genetics are needed to determine if there is a taxonomic basis to this ecological separation. Although the evidence is sparse, it is concluded that, in the NE Atlantic, dense populations of Ditrupa are found in areas where the seabed is periodically disturbed by internal wave action. European and other habitat classification schemes require revision to reflect the areas of occurrence and benthic effects of internal waves.

High‐frequency cycles of brachiopod shell beds on subaqueous delta‐scale clinoforms (early Pliocene, south‐east Spain)

“…A review on its ecology by Hartley (2014) emphasizes two explanations for the high densities reported in modern environments, both associated with disturbances: (i) disruption of established benthic communities, enabling successful recruitment of high numbers of Ditrupa larvae; and (ii) post-settlement redistribution by storms and concentration in areas of deposition. It is therefore probable that the paucispecific fossil assemblages dominated by Ditrupa concentrations in FA3 are associated with the action of storms or internal waves, either by redeposition, by opportunistic responses to storm-induced siltation producing organic-rich substrates, or both (Ceregato et al, 2007;Hartley, 2014). The abundance of the benthic foraminifera Cassidulina carinata, Bolivina spp., Bulimina aculeata and Globocassidulina subglobosa (Fig.…”

“…The interpreted opportunistic behaviour agrees with its high dominance (Ceregato et al ., ), as in Pliocene outcrops in the Águilas and the neighboring Cope Basins (Martinell et al ., ). A review on its ecology by Hartley () emphasizes two explanations for the high densities reported in modern environments, both associated with disturbances: (i) disruption of established benthic communities, enabling successful recruitment of high numbers of Ditrupa larvae; and (ii) post‐settlement redistribution by storms and concentration in areas of deposition. It is therefore probable that the paucispecific fossil assemblages dominated by Ditrupa concentrations in FA3 are associated with the action of storms or internal waves, either by redeposition, by opportunistic responses to storm‐induced siltation producing organic‐rich substrates, or both (Ceregato et al ., ; Hartley, ).…”

Ecological patterns of polychaete assemblages associated with the Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767): a comparison of sites in two biogeographic zones (Adriatic and Aegean Sea)

“…On the other hand, the cosmopolitan status of some other species is currently questioned as they might represent species complexes, i.e., Ditrupa arietina (O. F. Müller, 1776), Exogone naidina Örsted, 1845, Salvatoria clavata (Claparède, 1863), Syllis armillaris (O.F. Müller, 1776), Trypanosyllis aeolis Langerhans, 1879) (López et al, 2001;San Martín, 2003;Hartley, 2014;Álvarez-Campos et al, 2017;Langeneck et al, 2018). Moreover, some species classified as cosmopolitan have complicated taxonomy or are purely identified and therefore erroneously reported in different geographic sectors (i.e., Heteromastus filiformis (Claparède, 1864), Lumbrineris coccinea (Renier, 1804), Lumbrineris latreilli Audouin & Milne Edwards, 1833) (Carrera-Parra, 2006;Capaccioni-Azzati & El-Haddad 2015).…”

Polychaetes of Greece: an updated and annotated checklist

“…Hartley (2014) points out different ecological preferences between populations of Ditrupa arietina in the Mediterranean and in the Atlantic and a sudden increase in population densities in the Western Mediterranean in the late 1980s, indicating the possibility of an unknown cryptic invasive species.…”