An Overview of Marine Non-Indigenous Species Found in Three Contrasting Biogeographic Metropolitan French Regions: Insights on Distribution, Origins and Pathways of Introduction

Biological invasions are one of the main global threats to biodiversity in terrestrial, freshwater and marine ecosystems worldwide, requiring effective inventorying and monitoring programs. Here, we present an updated list of non-indigenous species in French marine and transitional waters. Focused on eukaryote pluricellular species found throughout the three metropolitan French marine regions (Western Mediterranean Sea, Bay of Biscay and the Northern Seas), a total of 342 non-indigenous, including 42 cryptogenic, species are listed as having been introduced since the 13th century. The majority of the species originated from the temperate Northern Pacific. They mainly arrived through both ballast and hull fouling and also are associated with shellfish farming activities. Most of them have been introduced since the 1970s, a time when maritime and aquaculture trade intensified. Despite important human-aided opportunities for species transfer between the three marine regions (for instance, via recreational boating or aquaculture transfers), only a third of these NIS are common to all regions, as expected due to their environmental specificities.

Automated summary

Biological invasions pose a major threat to biodiversity in marine ecosystems globally, demanding effective inventorying and monitoring efforts. This study presents an updated inventory of non-indigenous species in French marine and transitional waters, focusing on multicellular eukaryotes across three marine regions. The list includes 342 non-indigenous species, of which 42 are cryptogenic, that have been introduced since the 13th century. The majority of these species originated from the temperate Northern Pacific and were mainly brought through ballast water, hull fouling, and shellfish farming activities.