Long distance kelp rafting impacts seaweed biogeography in the Northeast Pacific: the kelp conveyor hypothesis

Routine DNA barcoding of the H aida G waii seaweed flora revealed “endemic species” attributed initially to this region's past as a glacial refugium. However, subsequent barcode records from central C alifornia rapidly eroded this list leaving species characterized by disjunct distributions ( DD ) between C alifornia and H aida G waii. This observation prompted a more detailed look at species for C alifornia and B ritish C olumbia and revealed that 33 of 180 DNA ‐barcoded genetic groups in common between these regions (~18%) predominantly displayed DD between C alifornia and northern B ritish C olumbia. A previous discovery that a red abalone shell found in H aida G waii (far north of its range) had a float‐bearing kelp ( N ereocystis luetkeana ) holdfast attached to it prompted a closer consideration of the COI ‐5P barcode data in support of a “kelp conveyor hypothesis.” The hypothesis posits that there has been a net migration of C alifornian species to northern B ritish C olumbia the vector being species growing on substrata carried along with kelp rafts on the winter D avidson C urrent.