| Summary: | <i>Lanice conchilega</i> is one of the most common polychaetes on European sandy shores. Its tubes are up to 65cm long and the top 1- 4cm protrude above the sediment surface, ending in a sand-fringe. <i>Lanice conchilega</i> tubes are conspicuous physical habitat structures in an environment relatively poor in terms of three-dimensional structures. The aim of my studies was twofold, a) to investigate aspects of the aut- and population ecology of <i>L. conchilega,</i> i.e. the population dynamics, small-scale distribution patterns and the composition of the tubes, b) to determine effects of tube structures on the other benthic macrofauna. The studies were carried out at sandy shores exposed to strong tidal currents and waves in South Wales (UK) and relatively sheltered sandflats in the German Wadden Sea. Patterns of the population dynamics of <i>L. conchilega</i> and its small-scale spatial distribution varied considerably between sites and over time. Population densities could be persistent over years or were characterised by recurrent breakdowns and subsequent recovery. Juvenile recruitment was high in one population but absent in another, where post-larval recruitment seemed to play a major role. Distribution patterns could be random or highly aggregated, depending on the number of juvenile recruits and hydrodynamic forces. The presence of <i>L. conchilega</i> had marked effects on many other benthic species and changed the community structure. Tubes provided an attachment surface, refuge from predation and they altered current flow. Effects were strongly linked to the different distribution patterns of <i>L. conchilega </i>and the types of population dynamics. They were as ephemeral or persistent as the <i>L. conchilega</i> populations itself. Tube aggregations provided anchorage for some sessile species and may even function as foundation for mussel banks. In terms of their function as ecosystem engineers <i>L. conchilega</i> ranks between species providing sub-surface burrows and tubes and those with complex surface structures.
|
|---|
