BIOTIC Species Information for Ceramium virgatum
Researched byDr Keith Hiscock and Paolo Pizzolla Data supplied byMarLIN
Refereed byDr Fabio Rindi
Scientific nameCeramium virgatum Common nameA red seaweed
MCS CodeZM519 Recent SynonymsCeramium nodulosum, Ceramium rubrum

PhylumRhodophycota Subphylum
Superclass ClassRhodophyceae
SubclassFlorideophyceae OrderCeramiales
Suborder FamilyCeramiaceae
GenusCeramium Speciesvirgatum

Additional InformationDiscrimination of separate species of Ceramium is often difficult. This species can be identified with certainty only by careful microscopic observation and in the field can be easily confused with other species of Ceramium with similar morphology namely Ceramium botryocarpum, Ceramium pallidum and Ceramium secundatum (F. Rindi, pers. comm.). The above taxonomy uses the recent nomenclature from Hardy & Guiry (2003). The confusion concerning Ceramium nodulosum and Ceramium rubrum was discussed by Maggs et al. (2002).
Taxonomy References Dickinson, 1963, Fish & Fish, 1996, Maggs & Hommersand, 1993, Hiscock, 1986b, Maggs et al., 2002,
General Biology
Growth formFiliform
Feeding methodPhotoautotroph
Mobility/MovementPermanent attachment
Environmental positionEpifloral
Typical food typesNot relevant HabitAttached
BioturbatorNot relevant FlexibilityHigh (>45 degrees)
FragilityIntermediate SizeMedium-large(21-50cm)
Height Growth RateInsufficient information
Adult dispersal potentialNone DependencyIndependent
General Biology Additional InformationCeramium virgatum colonizes rock and algal habitats from the midshore in rockpools to the open shore near to low water level and in the shallow subtidal (see Maggs & Hommersand, 1993). It also grows attached to the leaves of Zostera marina (see, for instance, Whelan & Cullinane, 1985). It occurs on bedrock through to pebbles. Dickinson (1963) notes that the species is either perennial or pseudoperennial. Settlement onto new surfaces can be rapid. For instance, panels were colonized within a month of being placed in Langstone Harbour (Brown et al., 2001)
Biology References Dickinson, 1963, Brown et al., 2001, Maggs & Hommersand, 1993, Edwards, 1973, Whelan & Cullinane, 1985,
Distribution and Habitat
Distribution in Britain & IrelandFound on most suitable shores around Britain and Ireland.
Global distributionMaggs & Hommersand (1993) note that the 'Ceramium rubrum complex' is widely distributed in the North Atlantic but the distribution of component species requires reassessment.
Biogeographic rangeNot researched Depth range
MigratoryNon-migratory / Resident   
Distribution Additional InformationCeramium virgatum may be particularly abundant in the summer. It thrives in rockpools and occurs in still water situations where dilution with freshwater is likely to occur.

Substratum preferencesCobbles
Gravel / shingle
Artificial (e.g. metal/wood/concrete)
Physiographic preferencesOpen coast
Strait / sound
Ria / Voe
Enclosed coast / Embayment
Strait / sound
Biological zoneMid Eulittoral
Lower Eulittoral
Sublittoral Fringe
Upper Infralittoral
Wave exposureExtremely Exposed
Very Exposed
Moderately Exposed
Very Sheltered
Extremely Sheltered
Tidal stream strength/Water flowWeak (<1 kn)
Very Weak (negligible)
SalinityVariable (18-40 psu)
Full (30-40 psu)
Habitat Preferences Additional Information
Distribution References Dickinson, 1963, Fish & Fish, 1996, Maggs & Hommersand, 1993, Whelan & Cullinane, 1985, NBN, 2002, Hardy & Guiry, 2003, Hardy & Guiry, 2003,
Reproduction/Life History
Reproductive typeAlternation of generations
Developmental mechanismSpores (sexual / asexual)
Reproductive SeasonSee additional information Reproductive LocationAs adult
Reproductive frequencyAnnual protracted Regeneration potential No
Life span3-5 years Age at reproductive maturityInsufficient information
Generation timeSee additional information FecundityInsufficient information
Egg/propagule size Fertilization type
Larval/Juvenile dispersal potential10-100m Larval settlement period
Duration of larval stageSee additional information   
Reproduction Preferences Additional InformationEdwards (1973) reports that Ceramium virgatum (as rubrum) has a triphasic life history consisting of a sequence of gametophytic, carposporophytic and tetrasporophytic phases in which the first and the third are morphologically similar. Maggs & Hommersand (1993) report that spermatangia are recorded in January, March-April, June and August-September; cystocarps in January-February and April-September; tetrasporangia in February-September. Although no information on dispersal has been found directly for Ceramium virgatum, Norton (1992) concluded that dispersal potential is highly variable in seaweeds. Spores of Ulva sp. (as Enteromorpha) have been reported to travel 35 km, Phycodrys rubens 5 km and Sargassum muticum up to 1 km. However, the point is made that reach of the furthest propagule and useful dispersal range are not the same thing and recruitment usually occurs on a much more local scale, typically within 10 m of the parent plant.
Reproduction References Maggs & Hommersand, 1993, Norton, 1992, Edwards, 1973,
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