For years, scientists believed that a small, bushy form of seaweed in the Baltic, known as narrow wrack, was a separate species. However, through DNA sequencing, they have now discovered that this distinctive form is actually a giant clone of bladderwrack.

The clone has spread along the coast of the Bothnian Sea – the northernmost arm of the Baltic Sea – stretching over 500 km from the town of Öregrund to the city of Umeå (both in Sweden).

A clone occurs when an organism or cell is naturally replicated. The most obvious example of this is identical twins, where two offspring are produced from a single fertilised egg that splits. Clones occur throughout the natural world, from animals to plants – and seaweeds.

Bladderwrack typically reproduces through sexual fertilisation, with separate male and female wracks. But in this case, the female bladderwrack has been cloning itself. Fragments of the original organism break off and drift with the water currents, growing into new fronds.

This process has led to the creation of a vast, genetically identical population of bladderwrack that dominates certain areas of the Baltic Sea, explains Ricardo Pereyra, a researcher and lead author of the new study. However, as the Baltic Sea continues to warm, the future of this giant clone – and other seaweed species like it – remains uncertain.

Source: BBC Wildlife

Image: Kerstin Johannesson