Fróðskaparrit - 01.01.2007, Page 149

BOTNDÝR í BLEYTBOTNI Á FØROYSKUM FIRÐUM
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formation about species composition to-
gether witli chemical and physical descrip-
tions makes a powerful tool in managing
the use of the marine environment.
One of the most frequently used param-
eter to indicate increased organic enrich-
ment is a change in species composition
from a low domination towards a clear
domination by one or two species (Pear-
son, 1978; Pearson et al., 1983). In the
present paper we will mostly concentrate
on the dominant species. We will also give
information on generally used values of di-
versity measures from ten different Faro-
ese ijords and analyze the composition of
the fauna with regards to the major taxo-
nomic groups and to different feeding
types.
Only limited information on soft sedi-
ment species diversity is available for the
Faroe Islands. Josefson (1992; 2001) re-
ported from two localities on the Faroe
shelf (about 300 meters). Bloch et al.
(1986), Nørrevang (1990) Jørgensen
(1993) and Sakarisson (2000) have repor-
ted from the fjords (mainly Skálafjørður).
Materials and methods
The material in this paper consists of 63
grab samples from 10 different fjords in
the Faroe Islands sampled in the period
2001-2003. All samples were taken with
KC-Denmark 0.1 m2 van Veen grab. Depth
information was obtained from the echo
sounder on the vessel while the position
for each sample was obtained from GPS.
Sediments were visually and tactilely esti-
mated on location.
The sediments were sieved through a
set of 4 mm and 1 mm round hole sieves
before fixation in 4% formaldehyde sea-
water solution buffered in borax. Before
Divcrsity paranicters compared to environmental parameters
S N N/S H J’
All samplcs (61) 29 (5-66) 236 (8-620) 7.7(1.3-20.6) 3,5 (2.0-5.2) 0.74 (0.43-0.90)
Scdimcnt Mixed (18) 31 (23-44) 244 (74-527) 7.4 (2.6-12.9) 3.8 (3.0-4.4) 0.76 (0.57-0.90)
Sandy (21) 30 (5-66) 194 (8-485) 5.5 (1.3-13.3) 3.5 (2.0-5.2) 0.78 (0.47-0.90)
Silt/clay (22) 27 (18-39) 269(112-1655) 9.9 (4.2-20.7) 3.3 (2.1-4.3) 0.69 (0.43-0.89)
Depth < 20 m (22) 23 (5-44) 194 (8-527) 6.8(1.3-14.0) 3.1 (2.0-4.4) 0.73 (0.47-0.90)
20-40 (29) 33 (14-66) 267 (38-620) 8.3 (2.2-20.7) 3.7 (2.1-5.2) 0.74 (0.43-0.89)
> 40 m (10) 32 (18-44) 217 (112-388) 7.1 (4.5-15.5) 3.6 (2.8-4.5) 0.74(0.61-0.83)
lgnition loss < 30 mg/kg (8) 9(5-16) 38 (8-89) 3.8 (1.3-6.7) 2.5 (2.0-3.0) 0.82 (0.70-0.90)
30-60 mg/kg (32) 35 (17-66) 273 (38-620) 7.7 (2.2-20.7) 3.7 (2.1-5.2) 0.72 (0.43-0.89)
> 60 mg/kg (13) 28 (21-36) 291 (170-407) 10.5 (7.1-16,5) 3.4 (2.5-4.0) 0.70 (0.58-0.78)
Table 1. Average values of species numbers (S), individuals (N), individuals and species ratio (N/S), Shannon
diversity index (H) and Pielou evenness index (J’) in relation to sediment type, depth and ignition loss.
Minimum and maximum values are shown in brackets. Sample 7R and 7S are excluded from the calculations
because thcy are deviant.