The new kid on the block: Exploring the migration route, physiology and microbiome of the invasive seaweed Asparagopsis taxiformis

Climate change, marine transportation and the opening of Suez Canal are key factors affecting the marine ecosystem biodiversity of the Eastern Mediterranean. The red macroalgae Asparagopsis taxiformis (Delile) Trevisan (Bonnemaisoniales, Rhodophyta) is a highly invasive seaweed in temperate regions and is considered to be one of the ‘worst invasive alien species threatening marine biodiversity in Europe’. With the seawater temperature rising, A.taxiformis is found to settle in new territories, repressing local fauna. In the Mediterranean Sea, two cryptic lineages were reported before the opening of the Suez Canal, named L2 and L3. For the past two decades, A.taxiformis is present yearlong at the Israeli coastline with major blooms causing environmental nuisance. In our study, we demonstrate the path of invasion of new lineage of A.taxiformis using DNA barcoding and taxonomically identification by three molecular genetic markers (LSU, cox2-3 spacer, and rbcL). We found a cryptic lineage 4 (L4) of A. taxiformis first reported here for the Mediterranean Sea, and previously described for the western Indo-Pacific and Hawaii. Our results strongly indicate a Lessepsian migration route for A. taxiformis L4 with yet unknown consequences for the local marine ecosystems. To further study the implications and applications of this invader, we perform periodical collections form several sites along the northern Israeli coastline exploring the seasonal abundance, physiology, reproduction, metabolome and microbiome diversity.