Picture of
Our largest alga

Perennial primary shoots


Summer and winter appearance


Origin and distribution

Japweeds journey to Sweden

Establishment in Sweden and Denmark

Establishment and development in the Koster area

Development along the Swedish west coast

  Establishment in Sweden and Denmark

During the summer of 1987 attached examples of japweed were first observed in Sweden. This occurred in the Koster area in northern Bohuslän. During 1988 a further two populations were noted at the Väderöarna and within the Koster archipelago.
   By 1989, a further 38 locations of attached japweed populations were noted between the Norwegian border and the Gullmarsfjord.
   1990 represented a change in the development of the japweed populations in those areas that were established about 2 years before. Earlier, new areas with japweed were registered partly after type of biotope, but now even after colonised areas along beaches. Established populations "exploded" in number and plants up to 3m in length were observed. Attached individuals were noted the same year as far south as Mollösund.
   Until November 1991 new finds were registered north of Gullmarsfjorden, while reports futher south were scarce. However, attached examples were noted around the Tistlarna in the southern area of the Gothenburg archipelago during the summer of the same year. The colonisation process that started in 1990 in the northern areas has continued and spread further south. During 1992, this "front" was at the Gullmarsfjord, while 4 years later (1996) this "front" had reached Marstrand. The most southerly find of an attached individual in 1996 was just south of Varberg.





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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson