Náttúrufræðingurinn - 1970, Blaðsíða 30

24
NÁTTÚRUFRÆÐINGURINN
In 1965 several locations on the eastern coast of Iceland wcre investigated.
This part of the Icelandic coast is affected by Arctic water. Melrakkaslétta,
Langanes, Vopnafjörður, Mjóifjörður and Stöðvarfjörður were observed,
whereas tiie most detailed investigations took place in Reyðarfjörður. The
algal vegetation of this eastern fjord was compared with that of Dýrafjörður in
West Iceland. Observations showed that tlie algal growth found in the inner
and middle fjord areas was quite similar, while distinct differences were found
in the outer fjord regions. While a Gigartina stellata growth was found in the
lower littoral of exposed sites in the west, Porphyra linearis and Chordaria
flagelliformis were found in similar places in the east. Extensive Corallina offi-
cina/ií-fields, occupying lower littoral slopes in the west, could easily be compared
with Acrosiphonia-fields in the east. Furthermore, differences in algal vege-
tation between the western and eastern fjord are discussed.
Thc 1966 investigations were focused on the North Icelandic vegetation.
Steingrímsfjörður was studied and its algal vegetation compared with the
vegetation found in both the eastern and the western fjords. The algal vege-
tation of the outer fjord area was unlike the vegetation of both Dýrafjörður
and Reyðarfjörður. Halosaccion ramentaceum occupied the lower littoral
slopes, thus replacing Gigartina stellata. In addition, the eastern coast of Húna-
flói, Ólafsfjörður and Grímsey were observed. Atlantic characteristics were
still prevalent in the algal vegetation of these regions.
In 1967 the Snæfellsnes peninsula and Barðaströnd in Breiðafjörður were
thoroughly investigated. Great variations were found in the algal growth
around Snæfellsnes due to the varying configuration of the coastal rocks.
The limit of distribution of several species in either northerly or southerly
direction was found on this peninsula. It seems likely that this peninsula is
a threshold between the warm-boreal conditions in the south and the cold-
boreal conditions in the west.
The author found an extremely rich algal vegetation in Breiðafjörður and
some algal species, such as Dilsea edulis, Polysiphonia nigrescens and Phyllo-
phora hrodiaei, were found solely in this area.
In 1968 the vegetation of the transitional area in Southeast Iceland was
investigated, along the line Hornafjörður — Lón — Hvalnes — Álftafjörður —
Berufjörður, in order to find out where the influence of Arctic water on the
algal growth became first evident.
It appeared that the influence of this water was already noticeable around
Hornafjörður. Here all the typical Atlantic species disappeared from the vege-
tation (e.g. Chondrus crispus, Gigartina stellata, Ceramium-species, Callitham-
nion arbuscula, Corallina officinalis etc.). The algal vegetation of exposed,
rocky sites along this coastline was nontypical, being mainly represented by
an Ulothrix-Urospora belt throughout the littoral. The fjords Hornafjörður,
Papós, Lón, and Álftafjörður are landlocked, with estuarine growth conditions
and decreased tidal movements. Thus, the algal growth found in these estu-
arine fjords is not directly influenced by the oceanic waters. The algal vege-
tation of Berufjörður, on the other hand, showed some features common with
the vegetation of the mid-east area. Algal associations typical for eastern Ice-