Northern Ireland Non-indigenous Species

Non indigenous species (NIS) can have a negative impact on habitats and out compete native species. NIS have a tendency to spread in environments where they are not native due to the absence of natural predators or grazers. In some cases, they can drastically alter the habitat e.g. on the mainland coasts of Europe and also on the south coast of England, the Pacific oyster has replaced many of the native, rocky shore species, in some places forming dense aggregations of 700 individuals/m². NIS can also have serious economic impacts by competing with or replacing our native biodiversity and also by fouling structures such as marina pontoons, boat hulls, fishing gear, aquaculture ropes and enclosures and slipways. The invasive brown seaweed Rugulopteryx okamurae was accidentally introduced to the Strait of Gibraltar in 2015/2016 and has spread along Mediterranean and Atlantic coast where it has had a significant negative impact on local economies through its impact on tourism and fisheries.