This environmental impact assessment for Kriegers flak ... - Vattenfall

80 PRESENTATION OF THE AREA
regularly or sporadically within this group of stations.
Below the halocline the stations were divided in two
groups, ”B1” and ”B2”.
The Þ rst group mainly contained sand seabed (station
group B1). The stations within this group were
mainly placed between 28-38 metres depth although
some were at 40 metres depth. Common for all these
stations was low organic content, the humus content
was mainly less that 1 % of dry matter.
The structural element in this group was the blue
mussel M. edulis, which occurred at all stations in high
density. Also the Baltic mussel M. baltica, the polychaet
P. elegans and the crustacean Diastylis rathkei were
observed at all stations.
Nine further species were detected at more than half
of the stations, for instance Saduria entomon, Monoporeia
afÞ nis and Halicryptus spinulosus. Also these species
are species that usually are limited to the cold and
salt-rich waters below the halocline. The number of
species in this type of biotope was very high. In total,
62 different species and higher taxon were registered.
A high degree of salinity, low water temperatures
and sporadic incidents of oxygen shortage characterized
those under water stations below a depth of 40 m
which mainly constituted the group B2. In addition,
organic substance in the form of mud in hollow areas
was accumulated, the humus content was measured to
an average 3% and reached a maximum value of 10 %
of dry matter.
Five species could be observed at all stations in
group B2: D. rathkei, H. spinulosus, M. balthica, S.
armiger and the polychaet Terebellides stroemi. Also
the mussel A. borealis, the polychaets P. elegans and
Bylgides sarsi and also the Pontoporeia femorata and
the Priapulus caudatus were widespread (presence
of >75%). At more than half of the stations, the two
species of polychaets, Aricidea suecia and Ampharete
baltica, and the blue mussel M. eduli were found.
11.6.2. Fish
There are around 144 species of Þ sh in the Baltic of
which 97 species are salt water and 40 species are fresh
water Þ sh with 7 species alternating between salt and
fresh water (Thiel et al. 1996).
A survey carried out by IfAÖ on behalf of the Group
on the German side of Kriegers Flak identiÞ ed the following
27 species in the area:
Cod, whiting, haddock, plaice, common dab,
ß ounder, herring lumpsucker, eel, grey mullet, saithe,
turbot, sculpi, snakeblenny, spratt, viviparous blenny,
lumpsucker, blackgoby, rockgunnel, goldsinny-wrasse,
shortspined and sea scorpio. (For latin names and family
belongings, see Appendix 7.6.).
None of these are listed as endangered speices in the
Swedish register.
The surveys were carried out during 2002 and 2003
Overview over distribution of macrozoobentos in the south-western Baltic