With approximately 20 new non-native animals and plants discovered in European waters annually – and a staggering 70% of them found lurking in the Mediterranean – ocean experts are delving into the implications of these aquatic intruders. In the idyllic waters of Madeira, which are home to 70 non-indigenous species, researchers stumbled upon a troubling find just two years ago: a brown algae with the name Rugulopteryx okamurae. João Canning-Clode is the chairman of the Invasive Species Expert Group at ICES, the International Council for the Exploration of the Sea. He describes this algae disco…