Fucus spiralis

Researched By	Nicola White	Data Supplied By	MarLIN
Refereed by	Dr Graham Scott
Taxonomy
Scientific name	Fucus spiralis	Common name	Spiral wrack
MCS Code	ZR383	Recent Synonyms	None
Phylum	Chromophycota	Subphylum
Superclass		Class	Phaeophyceae
Subclass		Order	Fucales
Suborder		Family	Fucaceae
Genus	Fucus	Species	spiralis
Subspecies
Additional Information	A number of discrete forms of this species have been recorded. In the UK, a diminutive form Fucus spiralis nanus is relatively common.
Taxonomy References	Howson & Picton, 1997, Fish & Fish, 1996, Anderson & Scott, 1998, Scott et al., 2000
General Biology
Growth form	Foliose, Shrub	Feeding method	Photoautotroph
Mobility/Movement	Permanent attachment	Environmental position	Epifloral
Typical food types	Not relevant	Habit	Attached
Bioturbator	Not relevant	Flexibility	High (>45 degrees)
Fragility	Intermediate	Size	Medium-large(21-50cm)
Height	Up to 40 cm	Growth Rate	1.1 cm / month
Adult dispersal potential	None	Dependency	Independent
Sociability	Solitary
Toxic/Poisonous?	No
Additional Information	Fucus spiralis spends up to 90 percent of the time out of the water. It can tolerate a high level of desiccation, being able to survive 70 to 80 percent water loss. Distinct varieties of Fucus spiralis have been recognised, such as Fucus spiralis forma nanus, which is a dwarf form present on exposed shores. Fucus spiralis also hybridises with Fucus vesiculosus providing considerable difficulty in identification.
Biology References	Niemeck & Mathieson, 1976, Fish & Fish, 1996, Scott et al., 2000
Distribution and Habitat
Distribution in Britain & Ireland	All coasts of Britain and Ireland
Global distribution	Iceland, Norway, Denmark, Netherlands, UK, Ireland, Atlantic coast of France, Spain, Morocco, Azores, East coast of America from New Jersey to Nova Scotia and isolated reports in the Northern Pacific.
Biogeographic range	Not researched	Depth range	Lower littoral fringe
Migratory	Non-migratory / Resident
Distribution Additional Information	Fucus spiralis favours rocks with many cracks and fissures, which probably provide some protection for developing zygotes and adult plants. It can extend into estuaries up to the 10 psu isohaline. The presence or absence of suitable substrata is considered to be one of the most important factors determining the distribution of Fucus spiralis.
Substratum preferences	Bedrock, Large to very large boulders, Small boulders, Cobbles	Physiographic preferences	Strait / sound, Sealoch, Ria / Voe, Estuary
Biological zone	Lower Littoral Fringe	Wave exposure	Moderately Exposed, Sheltered, Very Sheltered
Tidal stream strength/Water flow	Strong (3-6 kn), Moderately Strong (1-3 kn), Weak (<1 kn), Very Weak (negligible)	Salinity	Reduced (18-30 psu), Variable (18-40 psu), Full (30-40 psu)
Habitat Additional Information
Distribution References	Niemeck & Mathieson, 1976, JNCC, 1999, Norton, 1985, Hardy & Guiry, 2003
Reproduction/Life History
Reproductive type	Vegetative, Permanent hermaphrodite	Developmental mechanism	Insufficient information
Reproductive Season	July to August	Reproductive Location
Reproductive frequency	Annual episodic	Regeneration potential	No
Life span	3-5 years	Age at reproductive maturity	1-2 years
Generation time	3-5 years	Fecundity	Insufficient information
Egg/propagule size	Insufficient information	Fertilization type	Insufficient information
Larvae/Juveniles Larval/Juvenile dispersal potential Insufficient information Larval settlement period Insufficient information Duration of larval stage Insufficient information
Additional Information	Fucus spiralis is hermaphroditic. Receptacles are initiated during late January to February, gametes discharged during July and August, and the receptacles shed by November, although exact timing of reproduction depends on location and the form of the plant. Young plants usually reach a length of 8 to 10 cm or more before they form receptacles. Reproduction usually begins before or during the second years growth. Vegetative recruitment occurs by the formation of new fronds from existing holdfasts. This form of reproduction is important in existing stands of the population, whereas recruitment by eggs is more important in disturbed areas or in areas where germlings are protected e.g. rock crevices.
Reproduction References	Niemeck & Mathieson, 1976, Robertson, 1985, Scott et al., 2000, Vernet & Harper, 1980