Current distribution and abundance of Austrominius modestus (Darwin, 1854) and other non-indigenous barnacles along the northern coast of Portugal

Abstract

The presence of non-indigenous barnacles on the north coast of Portugal was reported for the first time on the beginning of the second half of the past century. Since then, there is a lack of information to evaluate changes in the abundance and/or distribution of these barnacles. The aim of this study is to evaluate the current distribution and abundance of non-indigenous species of barnacles in northern Portugal, providing quantitative data that will be useful for future studies as baseline. To achieve this aim we explored the presence of non-indigenous species of barnacles using a quantitative sampling design along the coast of North Portugal. Three species of non-indigenous barnacles were found: Amphibalanus amphitrite, Amphibalanus improvisus and Austrominius modestus. The only species that showed a widespread distribution on the study area was A. modestus, with similar abundances in all the studied estuaries. On the other hand, A. improvisus and A. amphitrite showed a very limited distribution. This study provides the first quantitative data for these species in north Portugal, that will be useful to explore the evolution of their populations in the future.