BIOTIC

BIOTIC Species Information for Fucus serratus

Researched by

Angus Jackson

Data supplied by

MarLIN

Refereed by

Dr Graham Scott

Taxonomy

Scientific name

Fucus serratus

Common name

Toothed wrack

MCS Code

ZR382

Recent Synonyms

None

Phylum

Chromophycota

Subphylum

Superclass

Class

Phaeophyceae

Subclass

Order

Fucales

Suborder

Family

Fucaceae

Genus

Fucus

Species

serratus

Subspecies

Additional Information

Also known as serrated or saw wrack. Ripe male plants can be distinguished by their orange colour.

Taxonomy References

Howson & Picton, 1997, Hayward et al., 1996, Dickinson, 1963, Williams, 1996, Knight & Parke, 1950,

General Biology

Growth form

Shrub
Foliose

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

Large(>50cm)

Height

Usually up to 70 cm

Growth Rate

0.2-0.1 cm / day

Adult dispersal potential

None

Dependency

Independent

Sociability

Solitary

Toxic/Poisonous?

General Biology Additional Information

During most of the year plant densities range between 10-14/0.25 square metres. When recruitment is occurring then densities may rise to 18-22/0.25 square metres. Surface cover by this species may reach over 95 percent during the summer. This decreases and becomes more patchy during winter and autumn. Fucus serratus typically grows up to 70 cm but has been recorded at over 2 m in length in very sheltered environments. Growth rate refers to maximal growth rate under optimal conditions. Growth rate varies considerably depending on environmental conditions. Growth rate ranges from 4-12 cm per annum. There are two size classes: germlings less than 10 cm (30-40 percent of the population); and adult plants greater than 40 cm. The germlings developing from eggs are initially microscopic and become visible to the naked eye after about two weeks. There is no clear mode in between but individuals of intermediate size are always present. Fucus serratus supports a wide variety of epiphytes with over 90 species having been recorded. Growth of microalgae on the frond surface can cause shading and reduced photosynthesis, anoxia at the frond surface and may interfere with reproduction. Mobile herbivores may benefit Fucus serratus through removal of this algal film. Other dominant macrofaunal species found on Fucus serratus include Lacuna pallidula, Littorina mariae, Amphithoe rubricata, Idotea granulosa and epiflora include Rhydomenia palmata and Elachista fucicola.

Biology References

Creed et al., 1997, Brenchley et al., 1997, Seed & O'Connor, 1981, Lüning, 1990, Williams, 1996, Knight & Parke, 1950,

Distribution and Habitat

Distribution in Britain & Ireland

All British and Irish coasts.

Global distribution

Northern Portugal and the Atlantic coast of France; British Isles, North Sea coasts and into the western Baltic; Scandinavia up to Novaya Zemlya; Iceland and the Gulf of St. Lawrence in the western north Atlantic.

Biogeographic range

Not researched

Depth range

Not relevant

Migratory

Non-migratory / Resident

Distribution Additional Information

Depth in metres is considered not relevant because the species is intertidal. More exposed coasts have a lower proportion of adult individuals in the population. In more sheltered areas Fucus serratus may grow on substrata such as cobbles.

Substratum preferences

Bedrock
Large to very large boulders
Small boulders
Cobbles

Physiographic preferences

Open coast
Sealoch
Ria / Voe
Estuary

Biological zone

Wave exposure

Moderately Exposed
Sheltered
Very Sheltered
Extremely 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)
Full (30-40 psu)
Variable (18-40 psu)

Habitat Preferences Additional Information

Distribution References

Hayward et al., 1996, Williams, 1996, Knight & Parke, 1950,

Reproduction/Life History

Reproductive type

Gonochoristic

Developmental mechanism

Insufficient information

Reproductive Season

May to November

Reproductive Location

Water column

Reproductive frequency

Annual protracted

Regeneration potential

Life span

3-5 years

Age at reproductive maturity

Insufficient information

Generation time

Insufficient information

Fecundity

See additional information

Egg/propagule size

Insufficient information

Fertilization type

External

Larvae/Juveniles
Larval/Juvenile dispersal potential	>10km	Larval settlement period
Duration of larval stage	Insufficient information

Reproduction Preferences Additional Information

Dickinson, (1963) notes that fruiting fronds can be found almost throughout the year with fertile plants most in evidence during the winter months. However, most other work suggests that reproduction commences in late spring/early summer and continues through summer and autumn, peaking in August - October. Eggs and sperm are released into the water and fertilisation occurs in the water column. The eggs produce a sperm attractant called fucoserratin that is active within 0.5mm. The zygote then develops into a minute plant that can then settle onto the substratum. Post reproductive fronds are shed contributing to loss of surface cover. Many plants may be lost during winter due to storms and heavy wave action. Germlings have a high mortality, up to 83 % being recorded lost in 77 days on the Isle of Man. Reproduction occurs earlier and growth is faster on sheltered shores. Egg release is protracted. The largest number of receptacles recorded from a single plant is over 4,600. Eggs are broadcast into the water column to be carried by the current to settle and develop wherever they fall. Eggs attach firmly to the substratum within a few hours. Many eggs are eaten by browsing molluscs.

Reproduction References

Dickinson, 1963, Brenchley et al., 1997, Johnston, 1977, Williams, 1996, Knight & Parke, 1950,