Non-native species (NNS) are those which have been spread, either intentionally or accidentally, beyond their natural geographical range because of human activity. Invasive non-native species (INNS) can pose major threats to native biodiversity, human health and ecosystem services.
In 2018/9, rapid assessment surveys (RAS) of 14 ‘Clusters’ of three sites, one marina/harbour site, one nearby shore and one more distant shore, were completed in the Solent. That project developed a replicable survey methodology to map INNS on shores. Comparison of this information with inventories of INNS in the associated marinas enabled assessment of the risk of colonisation of natural shores by INNS from nearby marinas. Natural England wished to undertake similar work in Devon and Cornwall involving three ‘Clusters’ of sites to seek to establish if a similar relationship could be found between the prevalence of INNS found within marinas and INNS found on intertidal areas nearby and more distant shores.
Two of the new clusters, the Torbay MCZ, and the Fal & Helford SAC, supported the overall findings of the Solent study, that nearby shores have more NNS than more distant shores. This pattern supports the possibility that NNS are ‘leaking’ from marinas onto nearby shores.
Twenty-seven NNS in total were recorded. Where comparisons with earlier RAS were possible, there was a net increase in NNS records.
The survey method refined during these surveys has proved effective in providing evidence on the presence and abundance of NNS at such sites, contributing vital information to the designated site condition assessments.
Mapping Invasive Non-Native Species in the Solent: An Update – 2022