Aquatic Invasions Research paper Assessment of marine non-native species in 3 marinas in Falmouth Abstract In May 2010 Falmouth harbour commission approached Falmouth Marine School to carry out projects to aid research in the area; I wanted to look at life living on the pontoons and the amount of non-native species in the area. In July 2010 3 main marinas in Falmouth were surveyed for the presence of 7 invasive species known to be located at other locations within the UK: brown algae Sargrassum muticum and Undaria pinnatifida, a bryozoan Watersipora subtorquata, the pacific oyster Crassostrea gigas, and the squirts Corella eumyota, styela clava and Didemnum vexillum. The only surfaces monitored for non-native species were pontoon floats plastic, concrete and steel this was to limit the depth of the surveyed area (0.5m – 1m) All the marinas had one or more of the target species. bryozoans, orange tip sea squirt and leathery sea squirt was found at all marinas, pacific oyster was found at one marina carpet sea squirt was not found wireweed was found at all marinas and wakame only in the outer pontoon at Port Pendennis. The survey showed that recreational boating is an important factor for the dispersal of marine non-native species and that the marinas act as a good refuge for them. This survey could have been more affective if done on a wider scale over the whole of Cornwall to further our knowledge of the percentage of non-native species entering the UK. Keywords Non-native, Falmouth, invasive, marinas, percentage cover, rapid assessment. Introduction The introduction of non-native species to an ecosystem is one of the major causes of decreased biodiversity. They tend to disrupt the ecosystem by multiplying and out competing native species. Many alien species are transferred through ballast water transported during commercial shipping operations. Ship ballast water can transport up to 3000 species around the world every day. The marine alien programme was established in 2004 (www.marlin.ac.uk/marine_aliens/) to investigate the impacts and distribution of non-native species on indigenous species and the ecosystem of the UK. Non-indigenous species (NIS) are the second most important threat to biodiversity around the world. Invasive species can dramatically change the structure and function of the marine ecosystem by changing biodiversity and eliminating vital components of the food chain. There are 22 known non-native marine species found in ports and marinas around the UK at present compared to 1999 when only 7 were known (UK Biodiversity Action Plan) Sargrassum muticum (wireweed) Abundant along the shore line, attaches to hard surfaces in shallow water and can tolerate estuary conditions, rarely deeper than 5m. It out-competes local species as its fast growing and takes a lot of surface cover preventing light penetration to lower levels. S.muticum has spread along the south coast to the Isles of Scilly and along the north Cornish coast to Lundy. Populations have also been recorded in Northern Ireland and Scotland.
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