BIOTIC Species Information for Saccharina latissima
|Researched by||Nicola White and Charlotte Marshall||Data supplied by||MarLIN|
|Refereed by||Dr Joanna Jones|
|Reproductive type||Alternation of generations
||Developmental mechanism||Spores (sexual / asexual)
|Reproductive Season||Possibly all year - see additional information.||Reproductive Location|
|Reproductive frequency||Annual episodic||Regeneration potential||No|
|Life span||3-5 years||Age at reproductive maturity||1-2 years|
|Generation time||1-2 years||Fecundity||Insufficient information|
|Egg/propagule size||Insufficient information||Fertilization type||External|
|Reproduction Preferences Additional Information||
Overview of life history
Laminaria saccharina has a typical laminarian life history, in which a macroscopic and structurally complex diploid sporophyte phase alternates with a microscopic haploid gametophyte. The species is a short-lived perennial. Sporophytes (clearly visible adult plants) typically have a life span of 2 to 4 years, although plants may occur as annuals. Specimens over four years old have been recorded from a fjord in Greenland (Borum et al., 2002).
Timing of reproduction
Laminaria saccharina plants usually takes 8 to 15 months to reach fertility at which point the central portion of the blade is covered in unilocular sporangia, that produce zoospores by meiosis. Lüning (1988) reported that sorus (a group of sporangia) formation in Laminaria saccharina from Helgoland, in the Southern North Sea, was restricted to autumn conditions whilst Kain (1979) and Parke (1948) reported that, in the British Isles, sorus formation was most frequent in both autumn and winter. It has been suggested that, in the Arctic, Laminaria saccharina sporophytes may carry sori throughout the year and can therefore produce gametophytes in all seasons (Makarov & Schoschina, 1998, cited in Sjøtun & Schoschina, 2002). Similarly, Parke (1948) reported that in sheltered habitats on the south Devon coast, reproductive tissue was present in all months, although October to April was the most frequent period of spore production in the British Isles for this species.
Factors controlling reproduction
Experimental work using various red and blue light regimes suggest that the onset of fertility in female gametophytes is controlled specifically by blue light above a certain irradiance (Lüning & Dring, 1975). In their experiments, female gametophytes grown in red light for ten days continued to grow vegetatively with no egg production. In contrast, nearly 100% of gametophytes grown in blue light (1.5 nE cm-2 sec-1 (total irradiation per second)) over the same period became fertile. Equally, plants that had been grown in red light for two weeks became fertile after being irradiated with blue light (1-4 nE cm-2 sec-1) for a period of time. After 96 hours of irradiance almost 100% of gametophytes had become fertile. Lüning (1990) also concluded that only blue light induces fertility.
Lüning (1988) cultivated adult sporophytes near Helgoland in the Southern North Sea and cultivated them under various light regimes. Sori were only formed in the 'short day' regime (8:16 hours light:dark respectively). No sori were formed in the 'long day' (16:8) or 'night break' (8:7.5:1:7.5) regimes.
Lüning (1990) found that at 10 °C, the gametophyte could survive at least five months in total darkness.
Lee & Brinkhuis (1988) studied the effects of seasonal light and temperature interactions on the development of Laminaria saccharina gametophytes and juvenile sporophytes in Long Island Sound and found that, in general:
Sjøtun & Schoschina (2002) reported 100 % germination of embyospores at 0 °C in this species suggesting a good adaptation to Arctic conditions.
See 'sensitivity' (adult) section on temperature for further information.