Interim report of the HELCOM CORESET project

Gaps in the monitoring of the compound
Table 3.17. Gaps in the monitoring of the compound of TBT and imposex.
Country Gaps
Denmark Little geographic coverage around Bornholm. Time trend station at Bornholm will be established
from 2011 onwards. Sediments will be taken according to a rotating sampling scheme,
so no temporal trends will be available for sediments.
Estonia
Finland Sediment profi le sites not decided yet. TBT measurements are performed in fi sh not in
mussels.
Germany
Latvia No data about TBT in sediments and in mussels. TBT is not included in monitoring program
plan till 2012.
Lithuania Monitoring program does not include TBT measurements in biota.
Poland
Russia
Sweden
Present status assessments
Known temporal trends (also from sediment core profi les)
Since the EU ban on TBT, temporal trends showed that TBT concentration in sediments decrease as well as
in benthic biota and fi shes. In some regions TBT concentration remains high but decreasing trend can be
expected in a coming years.
Spatial gradients (incl. sources)
Evaluation of spatial gradient in all the Baltic Sea is rather diffi cult due to the gaps in geographical coverage.
Clear spatial gradients have been established in relation to areas with high ship densities, which are in
line with that ship traffi c is regarded as the main source of TBT in marine environments.
Quality Assurance of imposex
OSPAR has developed international monitoring guidelines for imposex and intersex in fi ve species of
marine snails (OSPAR 2008). An ICES guideline also exists for monitoring intersex in periwinkle (Oehlmann
2004). A detailed method description for imposex in the mud snail Hydrobia can be found in
Schulte-Oehlmann et al. (1997)
Quality Assurance in form of international workshops and intercalibrations has been organized almost
yearly by QUASIMEME since 1998. National workshops have also been organized three times in relation to
the Danish monitoring program NOVANA.
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