Growth and age of the Antarctic bryozoan Cellaria incula on the Weddell Sea shelf

We analysed growth of the arborescent Antarctic cheilostome bryozoan Cellar ia incula by stable carbon and oxygen isotope analysis. The growth of one c omplete branch of C. incula takes one year, i.e. owing to the bifurcate col ony structure two new branches grow from each branch of the previous genera tion. The maximum age of a C. incula colony is likely to be more than 14 ye ars. Annual production-to-biomass ratio is 0.67, the highest value hitherto measured for ally benthic invertebrate south of 62 degrees S. Comparativel y fast growth and high productivity identify C. incula as a pioneer species which is able to quickly occupy spatial niches produced by iceberg scourin g on the Antarctic shelf.