Fróðskaparrit - 01.01.2008, Page 157

SNÍKAR í FØROYSKUM KOMBIKKI, GASTEROSTEUS ACULEATUS L.
155
2002 2003 2004
TO S S S+G
SK S S+G S+G
KL S+G S S+G
KA G S S+G
KR S S S
Rl S S S
Table 2C Intensity ofinfection with Trichodina sp.
(skin only). S=skin (fins included). C=gills (inside
gill cavity)
(Kaldbak, in 2002) only gills were infected
(see Tables 2A, 2B and 2C). According to
Ozer (2003) this should be T. tenuidens.
The highest number found ofTrichodina
(both species) on one fish was 305 (Kráargil,
in 2003).
A two-way-ANOVA-test of total num-
ber Trichodina (both species) sp. for all 1105
fish (length and year included) showed that
a significant difference was between locali-
ties (p<0.001). There was also a significant in-
teraction between localites and years
(p<0.001), indicating that special effects
were observed for certain localities in certain
years. A significant difference between years
could be seen (p=0.03), but the interpreta-
tion is not straightforward, because of the in-
teraction. Seven outlayers are included in the
material, but the result was unchanged, if
they were removed.
2. Metazoa
2.1 Thersitina gasterostei (Crustacea,
Copepoda), Figs. 3A-B and Figs. 4A-C
Thedistribution ofthisexternal parasite was
strictly marine, it was not found in the three
freshwater localities and one marine (Kald-
bak). There is a tendency of attaining more
parasites per fish when prevalence of infec-
tion is low (Fig. 3A and 3B). The difference in
numbers ofThersitina between left and right
side of fish is not significant, neither between
years nor localities (paired sign-test and chi-
square, p>0.05). Hence the total counts from
the two sides are shown in Figs. 3A and 3B.
Highest number of Thersitina gasterostei
on one fish was 52, which was found three
times (in fish from Kráargil 2002 and 2004
and in one fish from Rituvík 2003).
Fig. 4A Photograps o/Thersitina gasterostei, (below the operculum) at different magnifications.