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SEAWEEDS (ALGAE)

P.A.Gainey & P.E.Tompsett

The very long Cornish coastline with its numerous inlets provides a wide diversity of habitats which has ensured that the region is well represented with regards to the marine algae. Many of the algal species which are found here have a distinctly southern and western distribution in the British Isles. The problems associated with recording marine algae, especially those in the subtidal zone, are obvious. This, in conjunction with the fact that many of the algae are small and difficult to identify, may mean that many of them are somewhat more common than it would at first appear. Many of these rarer algae are difficult to identify positively, and have been recorded by only a few experts such that the distribution merely reflects where these algologists have been looking. Given these constraints, the following lists indicate those species thought to be very rare or scarce around the coastline of Cornwall and the Isles of Scilly at the present time.

There is currently no official Red Data Book (RDB) for the great majority of algal species, however, Brodie et al. (2007) list important sites for marine algae in the United Kingdom and also attempt a “rarity assessment” of many of the least common species. They identify the Falmouth Bay and Estuary, the Helford Estuary, the Isles of Scilly, the Tamar and Plymouth Sound as Important UK Plant Areas for marine algae and also potentially in a European context, exhibiting a particularly diverse algal flora with numerous interesting and rare species many of which have the type locality here. Hardy & Guiry (2003) published a phycological checklist and atlas of the seaweeds of Britain and Ireland which has provided a good overview of the various algal species and their standardised nomenclature has been followed here.

The marine algae listed here are designated as provisional RDB for Cornwall species in order to indicate that they would possibly be considered for inclusion in a Red Data Book of Marine Algae, should such a book ever be produced. In addition to these potential RDB species, the relatively warm, clear and unpolluted water of the Cornish coastline also acts as host to other algal species. Many of these would be considered as Nationally Scarce if the same criteria used for other groups of organism, were applied to them. These species are listed separately.

A wide range of sources was used when preparing this account, including Brodie & Irvine (2003), Brodie et al. (2007), Brodie, Maggs & John (2007), Dixon (1959), Farnham & Bishop (1985), Gainey (2003), Gill & Mercer (1989), Guiry & Guiry (2009), Hiscock, K. (1984), Hiscock, S. (1979; 1985), James (1983), Maggs & Hiscock, (1979), Price et al. (1980, 1981), Rostron & Hiscock (1987), Russell (1968) and Scruby et al. (1989). The authors are very grateful to Dr Juliet Brodie (British Natural History Museum) for her helpful involvement in the preparation of this account. Species are listed here alphabetically.