The colonial tunicate Botrylloides diegensis is presumably native to the northwestern part of the Pacific Ocean. It has been able to colonise new areas through hull fouling on ships. The first report of this species in Europe dates back to 2002 (the Netherlands). The first recorded observation on Belgian territory was in 2019. Currently, this tunicate is found in the marina of Zeebrugge and the port area of Ostend. The species is found on hard substrates such as in marinas, harbor docks, oyster reefs, rocks, and ship hulls. |