Colonisation, Growth and Interactions of Carpet Sea Squirt (Didemnum vexillum) dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS114860 The Carpet Sea Squirt (Didemnum vexillum) is a Invasive Non Native (INN) filter feeding marine invertebrate that forms large colonies carpetting hard structures on which it grows. Carpet Sea Squirt (Didemnum vexillum) was only confirmed in British waters in 2008. However, there are strong concerns that it will quickly colonise a much wider area as it has been found to do in other countries such as New Zealand and the USA. After an initial survey to identify the extent of colonisation, an eradication programme was undertaken by the Countryside Council for Wales. A programme of monitoring was initiated to measure the success of the eradication experiment and subsequent recolonisation and a research project undertaken in conjunction with Bangor University. The purpose of this data capture was to assess patterns of settlement, growth, colonisation and species interactions of Didemnum vexillum within Holyhead Marina from season to season. Also to look at how different disturbance magnitudes have negative or positive effects on Didemnum vexillum settlement and recruitment. 20120630