Recolonization pattern of the polychaete Lanice conchilega on an intertidal sand flat following the severe winter of 1995/96

Abstract

The recolonization process of Lanice conchilega was studied on an intertidal sand flat in the northern Wadden Sea after an intertidal population had been wiped out during the severe winter of 1995/96. After very low recruitment in the first two years, the population fully recovered in the third year after its destruction. By then, the distribution pattern closely resembled the pattern before the severe winter with >95% of all Lanice occuring below -0.5 m mean tidal level and dominance of the density categories 6-50 individuals (ind) m-2 and 51-200 ind m-2. Lanice larvae have been observed to attach preferentially on the tubes of adults. However, the high recruitment in the third year was also seen in areas devoid of adult Lanice, indicating that settlement facilitation by adults was of little importance for the recolonization process. Instead, we suggest that the observed recruitment pattern was a consequences of a large-scale decline in the metapopulation in the tidal basin and the onshore coastal subtidal which resulted in insufficient larval supply onto the tidal flats and low recruitment in the first two years following the severe winter.