The report summarises the monitoring activities within the National Swedish Contaminant Programme in marine biota.

Time series of analysed contaminants (heavy metals, organochlorines, brominated flame retardants, perfluorinated substances and polycyclic aromatic hydrocarbons) in biota are presented together with summaries of the results from the statistical analyses. The data represent the bioavailable portion of the investigated contaminants i.e. the portion that has effectively passed through biological membranes and may cause toxic effects. The report does not in general give background or explanations to significant changes found in the time series. Thus, increasing concentrations highlight the need for intensified studies.

- There was no general trend in heavy metal concentrations except for lead that is generally decreasing over the study period (in time series of sufficient length), supposedly due to the elimination of lead in gasoline.

- Generally, decreasing concentrations were observed for organochlorines (DDT’s, PCB’s, HCH’s, HCB), also including TCDD-equivalents over the whole study period, but not during the last decades. The chlorinated compounds generally show higher concentrations in the Bothnian Sea and/or Baltic Proper when compared to the Bothnian Bay and the Swedish west coast.

- Increasing trends of brominated flame retardants in guillemot eggs from late 1960s until early 1990s for polybrominated diphenyl ethers such as BDE-47, -99 and -100 and until mid-2000s for HBCDD, but with decreasing concentrations during the more recent time period. The PBDEs and HBCDD show higher concentrations in the Baltic Sea compared to the Swedish west coast.

- A consistently increasing concentration of PFOS in guillemot eggs has been observed throughout the whole time period, however, during the most recent ten years a change of direction is seen.