Maerl

Maerl (also rhodolith) is a collective name for non-geniculate coralline red algae with a certain growth habit. Maerl grows at a rate of c. 1 mm per year. It accumulates as unattached particles and forms extensive beds in suitable sublittoral sites.

Maerl is dredged from the sea floor and crushed to form a powder. It is still harvested around the coasts of Brittany in France and Bantry Bay, Ireland, and is a popular fertilizer for organic gardening.

Pictured here are Breton farmers waiting for the boats to deliver maerl, typically dressed in bleu de travail and beret.