Victorella pavida

Researched ByMichelle Carter & Angus JacksonData Supplied ByMarLIN
Refereed byThis information is not refereed.
Taxonomy
Scientific nameVictorella pavidaCommon nameTrembling sea mat
MCS CodeY100Recent SynonymsNone
PhylumBryozoaSubphylum
SuperclassClassGymnolaemata
SubclassOrderCtenostomatida
SuborderCarnosaFamilyVictorellidae
GenusVictorellaSpeciespavida
Subspecies  
Additional InformationNo text entered
Taxonomy References Howson & Picton, 1997, Hayward, 1985, Gainey, 1997, Carter, 2004
General Biology
Growth formMatFeeding methodActive suspension feeder
Mobility/MovementPermanent attachmentEnvironmental positionEpifaunal, Epilithic, Epiphytic
Typical food typesMicroalgae, rotifers.HabitAttached
BioturbatorNot relevantFlexibilityLow (10-45 degrees)
FragilityIntermediateSizeVery small(<1cm)
HeightGrowth Rate8 cm/month
Adult dispersal potentialNot researchedDependencySee additional information
SociabilityColonial
Toxic/Poisonous?No
Additional Information

Environmental position
At Swanpool, the trembling sea mat can be found growing on any hard surfaces such as stones, traffic cones, and concrete structures but has a particular predilection for submerged stems and rhizomes of Phragmites australis.

Associated fauna
Several taxa are consistently present living amongst Victorella pavida colonies, and on the Phragmites reeds, forming a community of aquatic organisms collectively termed 'Aufwuchs'. Taxa typically present include: chironomid larvae, nematodes, protozoans Stentor spp., and Zoothamnium spp., green and brown algae, mites, Nais spp., freshwater bryozoan Plumatella repens, and various small freshwater crustaceans including Gammarus chevreuxi.

Growth rate
Approximately 8 cm of linear growth over 1 month was observed in cultured colonies of Victorella pavida (Carter, 2004).

Biology References Carter, 2004, Evans et al., 2003
Distribution and Habitat
Distribution in Britain & IrelandIn the British Isles, Victorella pavida is only found in Swanpool: a brackish water lagoon near Falmouth in Cornwall.
Global distributionVarious sites on the southern shores of the North Sea on the European Mainland. Common in the Mediterranean. Also reported from India, the Black Sea, the Baltic, Brazil, the eastern United States and Japan.
Biogeographic rangeNot researchedDepth range5m
MigratoryNot relevant
Distribution Additional Information

Salinity
The salinity of Swanpool is highly variable (0.5-22 psu) (Carter, 2004). A culvert connects the lagoon to the sea, with the incursion of seawater occurring on very high tides such as spring tides. At the northern end of Swanpool, the lagoon is fed freshwater from the Tregoniggie stream as well as diffuse drainage from a local catchment (Gainey, 1997; Evans, 2003).

Substratum/habitat
Victorella pavida can grow on any hard surface and in Swanpool can be found growing on concrete surfaces, stones, traffic cones and mainly %Phragmites australis%.

Substratum preferencesArtificial (e.g. metal/wood/concrete), Other species (see additional information), MixedPhysiographic preferencesIsolated saline water (Lagoon)
Biological zoneLagoonalWave exposureNot relevant
Tidal stream strength/Water flowInsufficient informationSalinitySee additional Information
Habitat Additional Information
Distribution References Hayward, 1985, Carter, 2004, Dorey et al., 1973
Reproduction/Life History
Reproductive typeProtandrous hermaphrodite Developmental mechanismLecithotrophic
Reproductive SeasonJune to SeptemberReproductive Location
Reproductive frequency Regeneration potentialNo
Life spanSee additional informationAge at reproductive maturity<1 year
Generation time<1 yearFecundityCa 25 eggs per gravid zooid
Egg/propagule sizeFertilization type
Larvae/Juveniles
Larval/Juvenile dispersal potentialInsufficient informationLarval settlement period
Duration of larval stage<1 day  
Additional Information
Life span
The life span of an individual zooid has not been researched in this species. Generally, the polypides (combined lophophore and gut) of individual zooids within a bryozoan colony have the potential to undergo a cyclical degeneration and regeneration process. Polypides may last for one week up to 10 weeks (Reed, 1991). With respect to the life span of a Victorella pavida colony, new colonies emerge from dormancy during the spring and when temperatures are approximately 13°C. By November and the onset of winter, zooids begin to degenerate and eventually only the asexually produced dormant resting bodies (hibernacula) remain. The hibernacula germinate again in the spring and the cycle begins again (Carter, 2004).

Reproduction frequency
Reproduction is seasonal and eggs were observed in zooids from June to September. Following reproduction the colony will degenerate in preparation for winter dormancy (Carter, 2004).

Fecundity
Approximately 25 eggs can be produced per gravid zooid (Carter, 2004). Overall colony fecundity, therefore, varies with size of the colony.
Reproduction References Reed, 1991, Carter, 2004