Fróðskaparrit - 01.01.1998, Side 69

ORGANOTIN OG IMPOSEX í STRANDARØKINUM í FØROYUM
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Results
Organotin compounds and imposex
in dogwhelks
Five out of six dogwhelk populations
showed clear signs of imposex with VDSI
> 4, tab. 2, and contained sterile females.
No sign of imposex was seen in dogwhelks
from Kirkjubøur. Kirkjubøur is a small vil-
lage facing a sound with strong currents
promoting a frequent exchange of the water
masses. There are no fish farming, no ship-
yard, and only a few small leisure crafts in
the harbour. This station was thus expected
to be the least influenced by TBT.
The organotin species detected were
monobutyltin (MBT), dibutyltin (DBT)
and tributyltin (TBT), levels ranging from 1
- !7 ng Sn g"1 d.w, tab. 2. The relationship
between the three species was always TBT
> DBT > MBT. The concentration range for
TBT found in dogwhelks from the Faroe Is-
lands, tab. 2, was generally lower than
found along the Norwegian coast (<7-1096
ng Sn g'1 d.w.) (recalculated from Berge et
al. 1997).
According to Skarpheðinsdóttir et al.
(1996) summer levels of TBT in dogwhelks
are five times the winter levels. Norwegian
dogwhelks were generally collected during
late summer and autumn while sampling at
the Faroe Islands was conducted in late
winter. Since the samples from Norway and
the Faroe Islands are not collected in the
same season, direct comparison of levels of
contamination are impossible. If, however,
the concentrations of organotin compounds
Station Nr. Date nb % d.w.£ U1 mm VDSI sVDSI RPSI MBT DBT TBT
F M F M F M F M F M
Tórshavn
Argir la 03.03.96 25 28 22 32 28 4.4 0.5 32 2 2 5 6 17 16
Krkjubøur 2 17.02.96 20 27 26 31 30 0.1 0.5 0 <1 <1 2 2 2 4
V stmanna T ongisvágsfjørður 3 17.02.96 29 32 27 33 30 4.3 0.5 13 1 <1 <1 2 <1 5
Kolatoftir Ksaksvík 4 31.01.96 20 27 25 34 33 4.4 0.6 31 3 <1 7 4 15 8
Kunoy 5 04.03.96 24 32 28 32 32 4.1 0.3 13 1 <1 2 3 4 4
Nolsoy
Víkin" 6a 05.03.96 23 33 n.a.e n.a. <1 n.a. <1 n.a. 5
Kirkjutangi 6b 05.03.96 21 32 26 30 30 4.3 0.5 8 <i <1 <i <1 <i <1
a Too few females collected to determine imposex-level and organotin concentrations,
n = number of females used in imposex-determination,c d.w. = dry weight,d L= shell length,
e n.a. = not analysed
Tdb. 2. Mean vas deferense sequence index (VDSI), relative penis size index (RPSI) and concentrations of
organotin compounds in dogwhelks (Nucella lapillus) collected along the coast ofthe Faroe Islands in 1996.
Levels given in ng Sn g'1 d.w. F = Females, M = Males, sVDSl = VDSI standard deviation.
Taiva 2. Miðal vas deference sequence index (VDSI), relativt penis size index (RPSI) og innihald av organotin
evnum í purpurkúvingum (Nucella lapillus) sum vórðu tiknir fram við strendumar í Føroyum í 1996. Nøgdirnar
eru vístar sum ng Sn g"1 t.e. (t.e. = turr evni). F = kvenndýr, M = kalldýr, sVDSI = VDSI standard frávik.