marine ecology progress

coral reef

salt marsh

communities

benthic macrofauna

abundance

reefs

assemblages

deep sea

Marine Biology

The common tube-building polychaete Lanice conchilega is known as a habitat structuring species and can form dense aggregations. The eVects of L. conchilega on the surrounding benthic community have received little attention, especially in subtidal areas. Therefore, the pres- ence of L. conchilega in diVerent habitats in the North Sea and its eVect on the abundance, species richness, diversity and community structure in these habitats are evaluated in the present paper, based on data from the ICES North Sea Benthos Survey of 2000. Lanice conchilega has a wide geographical distribution and a low habitat specialization, but optimally occurs in shallow Wne sands. In the present study, the presence of L. conchilega resulted in a density increase and a signiWcant (positive) correlation of the ben- thos density with the density of L. conchilega. Furthermore, the species richness (number of species) increased with increasing density of L. conchilega. This trend was, how- ever, not consistent: the number of species reached more or less an asymptotic value or even decreased after reaching a critical density of L. conchilega (>500-1,000 ind/m²), as observed in shallow Wne sands. The same overall pattern was detected concerning the expected number of species. The N1-diversity index showed similar or slightly higher values in L. conchilega patches compared to patches with- out L. conchilega. From the results of the community anal- ysis, it can be concluded that the species, which were responsible for the increase of the diversity, belonged to the overall species-pool of that habitat. The eVects on density and diversity diVered between the four discerned habitats (shallow muddy sand, shallow Wne sand, shallow medium sand and deep Wne sand), and were most pronounced in shallow Wne sands. These patterns can be attributed to the habitat structuring capacity of L. conchilega. The mecha- nisms responsible for the increase of the habitat quality in patches of L. conchilega can be summarized as (1) changes in the hydrodynamics, (2) ...

Ecological implications of the presence of the tube-building polychaete Lanice conchilega on soft-bottom benthic ecosystems