Meeting Abstract

P2.71  Tuesday, Jan. 5  Colony fusion common in a colonial ascidian WESTERMAN, E.L.*; DIJKSTRA, J.A.; HARRIS, L.G.; Yale University; Wells National Estuarine Research Reserve; University of New Hampshire erica.westerman@yale.edu

Many benthic colonial invertebrates have the ability to fuse and form chimeras with compatible colonies. Botryllid ascidians fusion rates have been determined for different populations and species by random sampling and fusion testing individuals. However, natural fusion rates over time nor their influence on colony size have not been documented. We deployed six settlement panels to monitor the growth of single genotypes of ,Botrylloides violaceus and Botryllus schlosseri from July to September 2006 in Salem Harbor, Massachusetts, USA, and nine settlement panels to monitor settlement, growth, and fusion of Botrylloides violaceus from July to mid-August 2007. Eighty percent of the recruits observed fused with at least one other colony, while six percent neither fused nor were over grown. Growth rates of the fused colonies did not differ from those previously reported for single colonies. However, fused colonies were considerably larger than single genotype colonies at the end of the study period, and colonies in the 2006 study were significantly smaller than fused entities from 2007, though not smaller than single genotype entities from 2007. These results suggest that larvae are settling in clumps of compatible individuals, and that large subtidal colonies may be the result of high numbers of fusions between compatible colonies.