PUB - Publikationen an der Universität Bielefeld

Long-term density and distribution changes of benthic polychaetes in the Leschenault Inlet were monitored over a period of five years from February 1982 to May1987. A number of samples were also collected in 1997 for taxonomic purposes. A total of 15 polychaete species were recorded, one of which was a new species ( Ampharetidae sp. ). Spatial distributions of the dominant species could be linked to environmental factors, particularly to salinity regime, water depth and substrate. Specific habitat preferences were described and used to discern three polychaete assemblages. Salinity tolerance appeared to be the most important determinant of distribution patterns within the estuary. Long-term density changes of the three most common species Ceratonereis aequisetis , Nephtys gravieri and Capitella cf. capitata followed rather complex patterns. Average circannual periodicity of population density was typically unimodal, with peaks in late summer to autumn. Obvious circannual periodicity could not be found for the overall population of a given species, because both large year-to-year variability at single sites and phase differences between sites masked the average pattern. Coincident long-term trends observed for C . aequisetis at neighboring sites revealed a persistent synchronicity after disturbance and a lack of coupling to seasonal variation in abiotic factors.