BIOTIC Species Information for Ascophyllum nodosum
Researched byJacqueline Hill & Nicola White Data supplied byMarLIN
Refereed byDr Dagmar Stengel
Reproduction/Life History
Reproductive typeGonochoristic
Developmental mechanismSpores (sexual / asexual)
Reproductive SeasonInsufficient information Reproductive Location
Reproductive frequencyAnnual episodic Regeneration potential No
Life span11-20 years Age at reproductive maturity3-5 years
Generation time6-10 years FecundityInsufficient information
Egg/propagule size Fertilization type
Larval/Juvenile dispersal potentialInsufficient information Larval settlement period
Duration of larval stage2-10 days   
Reproduction Preferences Additional Information
  • Life span.
    Ascophyllum nodosum fronds can become up to 15 years old before breakage. The holdfasts, from which new fronds regenerate, are observed to exist for much longer so whole plants may live to be several decades old. Sundene (1973) found Ascophyllum nodosum needed five years to develop into fertile plants.
  • Time of first gametes.
    Mainly March and April, sometimes as early as January and February (D. Stengel pers. comm.).
  • Ascophyllum nodosum is dioecious and like all other species of fucoids has only a sexual generation. Receptacles are initiated in April and may take one year to become fertile. Thus, receptacles are present on the plant for 12-14 months and ripen in April to June of the following year. Gametes are released from April onwards and the release of gametes is triggered by the exposure of ripe receptacles to air overnight. Fertilization takes place externally and zygotes settle and form a rhizoid within ten days. The receptacles are then shed during June.
  • Recruitment.
    Recruitment in Ascophyllum nodosum is very poor with few germlings found on the shore. The reason for this poor recruitment is unclear, because the species invests the same high level of energy in reproduction as other fucoids and is extremely fertile every year (Printz, 1959). However, the reproductive period lasts about two months, much shorter than for other fucoids. Printz (1959) suggests that it must be assumed that some special combination of climatic or environmental conditions is needed for an effective recolonization of Ascophyllum nodosum. The slow growth rate of germlings, which increases the chance of their being covered by diatoms or grazed by Littorina, may also help to explain the scarcity of germlings (Baardseth, 1970).
  • Ascophyllum nodosum var. mackaii
    In Europe, direct reproduction of the ecad mackaii is vegetative and sexual reproduction gives rise to attached Ascophyllum nodosum. The formation of receptacles on intermediate ecad stages appears to be a frequent phenomenon, although abnormalities in receptacle shape and position usually accompany this (South & Hill, 1970). Sexual reproduction of intermediate and advanced forms of ecad mackaii in Newfoundland is relatively rare (South & Hill, 1970).
Reproduction References Baardseth, 1970, Printz, 1959, Bacon & Vadas, 1991, Sundene, 1973, South & Hill, 1970,
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