Fróðskaparrit - 01.01.1998, Page 72

78
ORGANOTIN AND IMPOSEX IN THE LITTORAL ZONE ON FAROE ISLANDS
Station Nr. Date Count Length, mm % d.w. MBT DBT TBT
Tórshavn
Argir la 03.03.96 49 41 14 <9 <9 <9
Sandagerði lb 29.02.96 62 41 16 54 62 90
Kirkjubøur 2 17.02.96 23 47 14 <9 <9 <9
Vestmanna 3 17.02.96 46 41 17 <9 <9 <9
T rongis vágsfjørður
Hvítanes 4b 31.01.96 35 52 17 <9 <9 <9
Nólsoy
Víkin 6a 05.03.96 21 50 17 <9 <9 <9
Kirkjutangi 6b 05.03.96 20 50 16 <9 <9 <9
Skálafjørður 7 01.03.96 31 46 18 <9 <9 <9
Tab. 4. Concentrations of organotin compounds in limpets (Patella vulgata) from the Faroe Islands, levels given
in ng Sn g'1 d.w.
Talva 4. Innihald av organotin evnir í fliðum (Patella vulgata) úr Føroyum, nøgdimar eru vístar sum ng Sn g4 t.e.
mussel carries a higher concentration of
TBT, amounting to approximately one or-
der of magnitude higher than in dogwhelks.
The higher concentrations in mussels may
be explained by the fact that these are filter
feeders, but the fact that the mussels were
sampled at more sheltered shores where the
water exchange is more limited, may also
be contributing to the higher build-up of
TBT.
Organotin compounds in limpets
Only one of the limpet samples analysed
contained detectable levels of organotin
compounds. The sample from Tórshavn,
Sandagerði (St.lb), contained 54, 62 and
90 ng Sn g"1 d.w. of MBT, DBT and TBT
respectively, tab. 4. High concentrations of
organotin compounds in common mussel
was also found at this station, tab. 3.
Conclusion
Effects of TBT, determined as imposex in
dogwhelks, were observed at all but one
station. At all of the stations showing impo-
sex, sterile females were found (VDSI>4).
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 (RPSI) in the popula-
tions. All common mussel populations in-
vestigated contained organotin compounds,
concentrations of TBT ranging from 49 to
372 ng Sn g."1 d.w. Only one of the limpet
populations contained detectable organotin
compounds.
Concentrations of organotin compounds
found in dogwhelks (Nucella lapillus) and
common mussels (Mytilus edulis) in this
investigation clearly demonstrate that
organotin compounds are present in most
coastal areas of the Faroe Islands, with
highest concentrations found near har-
bours. The main source for the introduction
of TBT to the marine environment today is
through the use of antifouling paints on
ships.