The status and ecology of reefs of Serpula vermicularis L. (Polychaeta: Serpulidae) in Scotland

Abstract

1. The distribution and abundance of reefs of Serpula 6ermicularis was examined in Loch Creran, the only known remaining site of reefs of this species in Scotland. In view of the decline in populations elsewhere, the aims included assessment of the importance of the Scottish population in terms of conservation of the reef habitat and the establishment of a baseline against which future changes could be gauged. A further objective was to determine appropriate conservation management of the reefs by examining the influence of both natural and anthropogenic factors.2. Reefs were largely restricted to a depth range of 1 -13 m. Factors controlling the depth distribution are discussed.3. Serpula 6ermicularis reefs colonized a variety of substrata, but predominantly grew on lamellibranch shells on a seabed of muddy sand. There was some evidence that reef abundance was influenced by the availability of suitable substrata. 4. A belt of scattered reefs fringed much of the coastline of the loch with profuse reef development at two sites, where reef coverage exceeded 10% of the seabed. In terms of total abundance of Serpula 6ermicularis reefs, Loch Creran represents the major world site for reef development. It is concluded that the reefs of Loch Creran are of significant nature conservation importance and grounds for the establishment of conservation management are discussed.5. Reef development is apparently curtailed in areas of strong currents and high flushing rate. There is evidence that human activity has adversely influenced reef growth through the discharge of organic factory effluent and the physical disturbance caused by mooring ground tackle. Scallop dredging also represents a significant threat to the persistence of serpulid reefs. Methods of minimising damage to this rare and fragile feature are discussed.

A high local species richness and biodiversity within high-latitude calcareous aggregates of tube-building polychaetes

“…Encrusting organisms with hard exoskeletons build secondary substrate and may increase substrate complexity with crevices and cavities (Dean 1981;Senn and Glasstetter 1989;Sebens 1991). A species rich and diverse fauna is thus often associated with aggregated calcareous-building species and non-tropical shallow-water examples are found in aggregations of red algae (Sneli 1968;Salas and Hergueta 1986;Sintes 1987;Sintes et al 1987) and serpulid polychaetes (Haines and Maurer 1980a, b;Kirkwood and Burton 1988;Moore et al 1998). Especially in canals and tidal inlets with high current velocities, reef-like structures of encrusting animals may develop (Odum et al 1974).…”

“…Their growth is fast and some species can develop reefs that are several meters thick and kilometres long (ten Hove 1979), which provide habitats, feeding grounds, refuge, and reproduction areas for an abundant and diverse fauna (Moore et al 1998). The genus Filograna is widely distributed, but due to the smallness of the tubes their aggregations are not spectacular (ten Hove 1979).…”

Where’s the ‘reef’? A five year study of serpulid tube bioerosion in a Scottish sea loch

“…In the British Isles, serpulid aggregations occur only in a few localities on the west coasts of Scotland ( Fig. 1) and Ireland (Minchin 1987, Moore et al 1998. The most extensive examples are found in Loch Creran, a fjordic sea loch in Argyll, west Scotland, where aggregations of Serpula vermicularis L. occupy a narrow depth band (1 to 13 m) fringing the loch periphery and covering a total area of ~108 ha (see Fig.…”

“…2 in Moore et al 2009 for distribution as of July 2005). The S. vermicularis aggregations in Loch Creran are regarded as biogenic 'reefs' (Holt et al 1998), and ongoing scientific studies aim to promote effective conservation management of this rare bio tope (Moore et al 1998, Poloczanska et al 2004, Chapman et al 2007, Hughes et al 2008.…”

“…A feature common to most definitions is the creation of elevated seabed topography by the accumulation of dead skeletal material, providing substratum for continued growth of the 'reef'-building organisms. In Loch Creran, Serpula vermicularis 'reefs' consist of masses of densely-intertwined tubes standing > 50 cm clear of the seabed and up to 60 cm in lateral extent (Moore et al 1998). Mature worms extend their tubes at a mean rate of 33 mm yr -1 (Hughes et al 2008).…”