BIOTIC Species Information for Fucus vesiculosus
|Researched by||Nicola White||Data supplied by||MarLIN|
|Refereed by||Dr Stefan Kraan|
||Developmental mechanism||Insufficient information
|Reproductive Season||December until late summer||Reproductive Location||Water column|
|Reproductive frequency||Annual episodic||Regeneration potential||No|
|Life span||3-5 years||Age at reproductive maturity||Insufficient information|
|Generation time||1-2 years||Fecundity||Possibly >1,000,000 eggs|
|Egg/propagule size||Insufficient information||Fertilization type||External|
|Reproduction Preferences Additional Information||The species is highly fecund often bearing more than 1000 receptacles on each plant, which may produce in excess of one million eggs. Development of the receptacles takes three months from initiation until gametes are released. On British Shores, receptacles are initiated around December and may be present on the plant till late summer. In Sweden receptacles were reportedly present from February through to October (Carlson, 1991).
In England, the species has a protracted reproduction period of about six months which varies only slightly in timing between a population at Wembury on the south coast of Devon and one at Port Erin, Isle of Man (Knight & Parke, 1950). Gametes may be produced from mid winter until late summer with a peak of fertility in May and June. According to Berger et al. (2001), Fucus vesiculosus reproduced in either of two periods in the Baltic, the first period being early summer (May - June) and the second being late autumn (September - November).
Plants are dioecious. Gametes are generally released into the seawater under calm conditions (Mann, 1972; Serrão et al., 2000) and the eggs are fertilized externally to produce a zygote. In the Baltic, summer spawning plants produced smaller but more eggs than plants reproducing in late autumn (September - November): egg production was approximately 210,000 eggs / gram frond mass with an egg size of 0.067 mm and 89,000 egg / gram frond mass with an egg size of 0.07 mm for summer and autumn periods respectively (Berger et al, 2001). Both periods experienced a similar recruitment success. Eggs are fertilized shortly after being released from the receptacle. On the coast of Maine, sampling on three separate occasions during the reproductive season revealed 100% fertilization on both exposed and sheltered shores (Serrão et al., 2000). Fertilization is not considered as a limiting factor in reproduction in this species (Mann, 1972; Serrã0 et al., 2000). Zygotes start to develop whenever they settle, even if the substratum is entirely unsuitable. The egg adheres to the rock within hours of settlement and the germling may be visible to the naked eye within a couple of weeks (Knight & Parke, 1950). The zygote is sticky (S. Kraan, pers. comm.) and may adhere firmly enough to resist removal by the next returning tide (Knight & Parke, 1950). Mortality is extremely high in the early stages of germination up to a time when plants are 3 cm in length and this is due mostly to mollusc predation (Knight & Parke 1950). In the Baltic, for example, a total of more than 1000 fertilized eggs per cm² were observed on the sea floor around the females over the two month reproductive season (Serrão et al., 2000). By the end of the season, however, the number of germlings growing in the same area was at least an order of magnitude lower.
The timing of reproduction in this species can, to a certain extent, be influenced by wave exposure and reproduction is sometimes initiated earlier in sheltered condition (Knight & Parke, 1950). In Finland, the amount of energy proportioned to reproduction was significantly higher on exposed sites than sheltered localities (Bäck et al, 1991).
|Reproduction References||Knight & Parke, 1950, Munda, 1997, Bäck et al., 1991, Serrão et al., 2000, Berger et al., 2001,|