Fróðskaparrit - 01.01.1998, Blaðsíða 62

68
ORGANOTIN AND IMPOSEX IN THE LITTORAL ZONE ON FAROE ISLANDS
found in the Arcachon Bay in France in the
late 1970s on the Pacific oyster (Alzieu et
al., 1986 with references). Effects of TBT
have since then been reported for a variety
of other marine species world-wide. In the
last decade much attention has been paid to
the induction of male sex characters in fe-
male snails, known as »imposex«, observed
mainly in neogastropods (Gibbs and Bryan,
1986). The development of a female penis
and vas deferens is probably caused by an
accumulation of a male hormone (testos-
terone) in the female dogwhelks. Sensitive
species may show such effects at TBT con-
centrations as low as 1 ng/L.
To evaluate the current status of organ-
otin pollution along the coast of the Faroe
Islands, dogwhelks, common mussels and
limpets have been analysed for concentra-
tions and effects of organotin compounds.
Levels of organotin compounds were deter-
mined by a method based on direct ethyla-
tion using sodium tetraethylborate and sub-
sequent analysis by gas chromatography
and atomic emission detection (GC-AED).
Levels of imposex in dogwhelk, Nucella
lapillus, populations were determined ac-
cording to the method by Gibbs et al,
(1987), which includes the determination
of the two parameters Relative Penis Size
Index, RPSL and Vas Deferens Sequence
Index, VDSI.
The concentrations of organotin com-
pounds in dogwhelks from the Faroe Is-
lands varied from below detection limits
(<1 ng Sn g"1 d.w.) to 17 ng Sn g"1 d.w. The
species detected were TBT, dibutyltin
(DBT) and monobutyltin (MBT). The max-
imum concentration was found in dog-
whelks from Tórshavn, the capitol of the
Faroe Islands.
Effects of TBT, determined as imposex
in dogwhelks, were observed at all but one
station (Kirkjubøur, VDSLO.l). Sterile fe-
males (VDSI>4) were found at all of the
other stations.
The concentration of TBT in dogwhelks
from the affected populations range from
below detection limits (<1 ng Sn g"1 d.w.) to
17 ng Sn g"1 d.w. while no TBT was found
in the unaffected population. A relation was
found between the levels of TBT and the
degree of imposex in the populations.
All common mussel populations investi-
gated contained organotin compounds,
concentrations of TBT ranging from 49 to
372 ng Sn g"1 d.w. DBT and MBT were also
detected, and the relation between the
species was always TBT > DBT > MBT.
This is similar to the relation found in com-
mon mussels from Norwegian waters
(Følsvik, 1997).
Only the limpet population from Tór-
shavn contained organotin compounds.
TBT, DBT and MBT concentrations were
90, 62 and 54 ng Sn g"1 d.w. respectively.
The results indicate widespread biologi-
cal effects and contamination by several
organotin species in the environment along
the coast of the Faroe Islands.
Introduction
Organotin compounds are generally of an-
thropogenic origin and in recent years there
has been growing concem about the detec-
tion of these compounds in the environ-
ment. In 1955 world production of organo-
tin compounds was approximately 5000