Effects of introduced sessile invertebrates: removal experiments.

Three removal experiments were conducted to test the effects of the introduced species, Bugula neritina, Ascidiella aspersa and Botryllus schlosseri on sessile invertebrate assemblages. Each experiment was run for approximately 2 months between 28th November 2004 and 13th February 2004. These experiments involved removing the introduced species from plates and then comparing these assemblages to those on disturbed control and control plates, where the introduced species had not been removed. The introduced species were removed by scraping them and surrounding species from the surface in 1/8 or 1/4 cm2 areas or by peeling individuals off with forceps. All individuals on the plates were counted and identified at the completion of the experiments.