Seaweed Biodiversity in Ireland

If we regard as seaweeds the larger, attached marine species of the red, brown and green algae, slightly over 500 different kinds occur in Ireland:






Ireland 274 147 80 501
Scotland 208 137 70 415
England & Wales 311 181 85 577
France 368 193 128 689
North Atlantic 620 329 256 1205

Numbers of seaweed species (red, brown and green) occurring in selected areas and in the whole of the North Atlantic. Data from Guiry (1996, AlgaeBase).

Although more species occur in England and Wales (taken together) than in Ireland, less are found in Scotland, and, considering smallness of the island, we have a remarkably high proportion of the marine algae of the whole of the North Atlantic basin. Many of these algae are relatively obscure species, known only to a handful of experts world-wide. Since 1979, our knowledge of Irish seaweed biodiversity has increased considerably (see Table above), due largely to more widespread subtidal investigations. Extensive taxonomic revisions have resulted in a seeming decrease in the total numbers of green algae, but the large increase in the red algae is mainly due to discoveries of previously unknown species, particularly in the subtidal of the west coast. Further taxonomic studies of our marine algae are needed, particularly of some of the supposedly well-known genera such as Fucus.