In 2017 The Marine Biological Association (MBA) carried out rapid assessment surveys (RAS) at a number of sites along the estuaries of the R. Itchen and the R. Hamble in the Solent as part of a wider study into the distribution of NNS in estuaries in southern England. The R. Itchen was surveyed from its tidal limit at Woodmill, down to where it meets Southampton Water. Natural England commissioned the work reported here to determine whether there has subsequently been any onward colonisation of INNS within the R. Itchen, and in particular of the Red-ripple bryozoan (Watersipora subatra), an invasive bryozoan which has been shown to be spreading widely in the Solent (and elsewhere) and was recorded at only one site at the mouth of the R. Itchen in 2019, subsequent to the baseline surveys in 2017.
