Fróðskaparrit - 01.01.2001, Page 120

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BRACHIOPODA IN THE FAROEISLANDS AREA
um. Two species, Terebratulina septentri-
onalis and Glaciarcula spitzbergensis, pre-
viously recorded by Wesenberg-Lund
(1940; 1941) have not been found.
The occurrence of H. psittacea is based
on one empty (not fossil) shell which was
probably transported into the area. (The in-
formation on the location of the station, the
estimated bottom temperature (7.7°C) and
the water mass (Atlantic Water-AW) at the
station versus the known cold water affini-
ty of the species, cf. Thomsen (1990), im-
plies transport from the colder north). P.
anomioides is new to the area. Wesenberg-
Lund (1940), however, suggested that it
may occur at the Faroe Islands as it has
been found north of Shetland.
C. anomala is found at 41 stations, T. re-
tusa at 125 stations, P. anomioides at 6 sta-
tions, D. septigera at 75 stations and M.
cranium at 157 stations.
All the Faroese brachiopods are sessile
epibenthic suspension feeders. One spe-
cies, the inarticulate C. anomala, is ce-
mented to its substrate, mostly pebbles.
The others are all articulate species with a
pedicle that attach them to a firm substrate
e.g. pebbles, corals, other brachiopods, i.a.
conspecific individuals.
In order to understand the biogeography
of the BIOFAR brachiopods, their distribu-
tion were mapped (Figs. 1-6) and compared
with bathymetric distribution (depth), tem-
perature (estimated average bottom tem-
perature), current (average maximum tidal
velocity in cm/s near bottom) and water
mass (Figs 7-8).
Geographic distribution (Figs. 1-6)
C. anomala, T. retusa, D. septigera and M.
cranium are all recorded around the Faroe
Islands and the southwestern banks. D. sep-
tigera, however, does not occur at the
westermost bank, Lousy Bank. P. anomi-
oides seems to be restricted primarily to the
banks, but the material is sparse.
Bathymetric distribution (Fig. 7 - left)
All species, except P. anomioides, seem to
prefer depths from 200 to 500 m. There are
very few records of P. anomioides, but this
species seems to prefer greater depths (398-
916 m). Both D. septigera and M. cranium
are recorded from greater depths, but the
number of records decline with increasing
depth. There are no records from depths
below 520 m for C. anomala.
Temperature (Fig. 7 - middle)
With the exception of D. septigera, all
species show a preference for bottom tem-
peratures above 6°C. D. septigera seems to
be able to tolerate lower temperatures as
well.
Current (Fig. 7 -right)
Brachiopods are dependent on some tur-
bulence to provide nutrients and oxygen for
reproduction and dispersal of the larvae.
Except for P. anomioides, all species seem
to prefer an average maximum tidal velo-
city ranging from 20 to 50 cm/s. D. septi-
gera perhaps being more susceptible pre-
ferring a narrower range (20 to 40 cm/s). It
is not possible to draw any conclusions on
the preference of P. anomioides due to the
small number of records.