176
1. Wallentinus
unpubi. data). In the late 1970s, sewage treatment was introduced in
Halden, and from 1978 the pulp mill effluents started to decrease and
stopped in 1991, when the plant was closed down. With decreased load
of organic material and toxic substances the nutrients from land runoff
may enhance algal growth in the area in the future. The localities for
macro algal studies from the 1980s were revisited in 1992 (Rueness et aI.,
unpubi. data). The distribution of several algae had moved inwards with
the improved water conditions (Lein et ai. 1974; Rueness et aI., unpubi.
data; L. Afzelius, pers. comm.). Thus in the early 1990s green algae such
as Cladophora sp., Enteromorpha sp. and Gayralia oxysperma could be
found very close to the river mouth, while in the 1970s the first two
seaweeds only occurred outside the bridge of Svinesund. In the 1970s,
Fucus vesiculosus was seen only in the outermost part of the bay, but in
the early 1980s had moved close to the bridge and 10 years later small
specimens occurred even inside the bridge. Also F. serratus had moved
slightly inwards and F. evanescens could be found in the outer area.
Cyanobacteria, which were the dominating autotrophs in the inner area
in the 1970s nevertheless were prominent, indicating that high concentrations of organic pollution still occurred.
6.4 The Norwegian South and Southwest Coasts
The macro algal composition along the southern coast of Norway does
not differ significantly from that of the Swedish Skagerrak coast (cf.
Rueness et ai. 1990). Several macroalgae have their eastern/southern
limits on the SW coast of Norway due to e.g. too low winter or too high
summer temperatures as well as a result of narrow tides. Examples are
the brown algae Alaria esculenta, Dictyota dichotoma, Fucus distichus
ssp. anceps, Himanthalia elongata, Pelvetia canaliculata, and the red
algae Ceramium shuttleworthianum, Mastocarpus stellata, Porphyra
miniata, and Vertebrata ( = Polysiphonia) lanosa (Rueness et ai. 1990).
In 1990, a 1O-year monitoring programme of hard-bottom communities was started by NIVA (Norsk institutt for vannforskning). The programme includes 27 stations from the Swedish border in the east to
north of Bergen, studied by transects, sampled squares, and stereo
photos. In some areas additional analyses of the epibionts and the length
of the stipes and lamina of Laminaria hyperborea are made (Pedersen
et ai. 1991; cf. also Moy and Walday 1992). Most of the stations are
located in the outer coastal zone, including four areas for intensive
1. Wallentinus
unpubi. data). In the late 1970s, sewage treatment was introduced in
Halden, and from 1978 the pulp mill effluents started to decrease and
stopped in 1991, when the plant was closed down. With decreased load
of organic material and toxic substances the nutrients from land runoff
may enhance algal growth in the area in the future. The localities for
macro algal studies from the 1980s were revisited in 1992 (Rueness et aI.,
unpubi. data). The distribution of several algae had moved inwards with
the improved water conditions (Lein et ai. 1974; Rueness et aI., unpubi.
data; L. Afzelius, pers. comm.). Thus in the early 1990s green algae such
as Cladophora sp., Enteromorpha sp. and Gayralia oxysperma could be
found very close to the river mouth, while in the 1970s the first two
seaweeds only occurred outside the bridge of Svinesund. In the 1970s,
Fucus vesiculosus was seen only in the outermost part of the bay, but in
the early 1980s had moved close to the bridge and 10 years later small
specimens occurred even inside the bridge. Also F. serratus had moved
slightly inwards and F. evanescens could be found in the outer area.
Cyanobacteria, which were the dominating autotrophs in the inner area
in the 1970s nevertheless were prominent, indicating that high concentrations of organic pollution still occurred.
6.4 The Norwegian South and Southwest Coasts
The macro algal composition along the southern coast of Norway does
not differ significantly from that of the Swedish Skagerrak coast (cf.
Rueness et ai. 1990). Several macroalgae have their eastern/southern
limits on the SW coast of Norway due to e.g. too low winter or too high
summer temperatures as well as a result of narrow tides. Examples are
the brown algae Alaria esculenta, Dictyota dichotoma, Fucus distichus
ssp. anceps, Himanthalia elongata, Pelvetia canaliculata, and the red
algae Ceramium shuttleworthianum, Mastocarpus stellata, Porphyra
miniata, and Vertebrata ( = Polysiphonia) lanosa (Rueness et ai. 1990).
In 1990, a 1O-year monitoring programme of hard-bottom communities was started by NIVA (Norsk institutt for vannforskning). The programme includes 27 stations from the Swedish border in the east to
north of Bergen, studied by transects, sampled squares, and stereo
photos. In some areas additional analyses of the epibionts and the length
of the stipes and lamina of Laminaria hyperborea are made (Pedersen
et ai. 1991; cf. also Moy and Walday 1992). Most of the stations are
located in the outer coastal zone, including four areas for intensive