Spatial and temporal distribution of macroalgal assemblages associated with the invasive Asparagopsis armata on intertidal rocky shore in Azores

Abstract

[EN] Rapid globalization and the increasing trends of trade, travel, and transport in recent decades have accelerated marine biological invasions. The Rhodophyta Asparagopsis armata is considered one of the most invasive species in European subtropical and temperate waters. A. armata, first recorded in the Azorean Archipelago in 1928, is now well established and very common in all Azorean islands, mainly between 5 and 20 m depth. Although having a wide distribution in the archipelago, little is known about its spatial and temporal variation and its impact on the invaded littoral communities. The present study aims to fill this gap and define spatial and temporal variations of the seaweed assemblages associated with the invasive Asparagopsis armata on low intertidal rocky shore. Three locations along the south coast of São Miguel Island were compared (Caloura, Lagoa and São Roque) in a monthly sampling between November 2016 and April 2017. According to our predictions, of temporal and spatial variability in the number of macroalgal taxa, there was an interactive effect between location and time. Environmental factors were proposed to account for this. A positive correlation between the abundance of Asparagopsis armata and the high diversity was found in Caloura, contrasting the venerable generalization of more diverse communities are more resistant to invasion. However, further studies taking into account its higher biomass peak (late spring) are needed in order to confirm this positive correlation.