Invasive Seaweed

Invasive seaweed has the potential to harm a coastal ecosystem by growing over native seaweed, starving it of light and nutrients and thereby damaging a habitat and food source for many marine animals.

Last June for example beaches in Massachusetts have been blanketed with thickly packed red fibers resembling matted hair, causing a stink for beachfront residents and tourists alike. The Pacific native Heterosiphonia japonica was likely introduced through ship ballast water. It was first discovered at US coasts back in 2009 but had already caused a lot of damage on European Coasts in the early 1980's.

The new exotic red algae found in Europe
(a Gracilariopsis chorda; b Chondracanthus sp.; c Solieria sp.;
d Gelidium vagum)

European researchers have now discovered four new invaders in the Netherlands and France, three of them likely introduced after 2008.  None of them has become a nuisance yet but according to the authors these species could have the potential to modify shore ecosystems if they became truly invasive. The authors used the rbcL gene to identify red algal specimens that could not be morphologically identified as native species or known introductions.

Responsible for these new introductions into Europe are likely imports of Pacific oysters (Crassostrea gigas) , either directly from the north-western Pacific, or as a secondary introduction from a different region (in Europe or overseas). Indeed, all the sites where the new species have been observed were in the close vicinity (within a few hundred meters) of shellfish farming or trading facilities.