Recent spread of non-indigenous ascidians (Chordata: Tunicata) in Icelandic harbours

ABSTRACT

Global shipping facilitates the introduction of fouling organisms to new geographic areas. The increase in maritime transport in recent decades has led to unprecedented development, where marine coastal waters have become one of the most invaded habitats around the globe. Among the most successful invaders are ascidians. Despite the geographic and oceanographic isolation of Iceland, it is far from being excluded as a recipient region. Ascidians have successfully been able to establish stable populations in Iceland that are slowly expanding around the SW region. Here we report the first record of Ascidiella scabra in Icelandic waters, and the spread of seven non-indigenous ascidians across the S-SW Icelandic harbours. We compare their relative abundances to our survey from 2018. The bulk of these ascidians is not only present in the temperate Atlantic Ocean, but also in the Northwest Pacific and temperate Australasia, revealing that global homogenization of the ascidiofauna is emerging in anthropized coastal areas. The rising of sea surface temperature, driven by climate change, is likely to continue to support the development of this scenario leading to biodiversity loss, which could endanger living resources with severe economic impacts.

KEYWORDS:

• Fouling organisms
• propagule
• colonization
• harbours
• coastal zones
• global homogenization

Acknowledgements

We thank the anonymous reviewers for their careful reading of the manuscript and their insightful comments and suggestions.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

ARE has received a grant from the University of Alicante (Spain) for carrying out short investigation actions in Iceland (Ref. ACIE21-11). This work was supported by Universidad de Alicante: [Grant Number ACIE21-11].