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.