Pathways for marine INNS (2020)

Occurrence and assemblage composition of intertidal non-native species may be influenced by shipping patterns and artificial structures

Didemnum vexillum © Julia Nunn

This study investigated the influence of shipping and man-made habitat modification on the occurrence and assemblage of intertidal non-native species in ports on the south coast of England.

Natural sites, such as rocky shores and artificial sites, such as sea and harbour walls, were sampled for non-native species. Non-native species were recorded on all sites using quantitative stratified-random quadrant sampling and timed searches. Most species were identified in the field; those that couldn’t be identified were transported to a laboratory to be formally identified.

A total of 26 non-native species were recorded in natural and artificial habitats across the study sites, including Austrominius modestus, Didemnum vexillum, Undaria pinnatifida, and Grateloupia turuturu. Many of these species were found in both artificial and natural environments, however natural sites may provide more suitable habitats, compared to artificial sites. 

The south coast of England receive ships from across the world and depending on the port, ship arrivals at study sites could between 0.4 to 86.4 a day. There are higher numbers of non-native species at busier ports compared to smaller ports. In general, artificial structures in ports may play a role in the introduction of these species by providing new habitats and aiding in transportation away from invaded sites.


O’Shaughnessy, K.A., Hawkins, S.J., Yunnie, A.L.E., Hanley, M.E., Lunt, P., Thompson, R.C. and Firth, L.B. (2020). Occurrence and assemblage composition of intertidal non-native species may be influenced by shipping patterns and artificial structures. Marine Pollution Bulletin, 154, p.111082. 

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