Levels and trends in marine contaminants and their biological effects – CEMP Assessment report 2023

This report summarises the 2023 annual CEMP assessment of levels and trends of contaminants and their biological effects. The full assessment is available online in the OSPAR Hazardous Substances Assessment Tool (OHAT): https://dome.ices.dk/ohat/?assessmentperiod=2023.

There were 14950 time series (of three years or more) in biota, of which 9687 were assessed for trends and 6359738 for environmental status and 2788 for human health status; 7635 time series in sediment, of which 3777 were assessed for trends and 5729 for status; and 1443 time series in water, of which 1082 were assessed for trends and 515 for status.

The 2023 annual CEMP assessment can be viewed on the OSPAR Hazardous Substances Assessment Tool (OHAT). It assessed 14950 time series (of three years or more) in biota, of which 9687 were assessed for trends and 9738 for environmental status and 2788 for human health status; 7635 time series in sediment, of which 3777 were assessed for trends and 5729 for status; and 1443 time series in water, of which 1082 were assessed for trends and 515 for status. Compared to the 2022 assessment, the number of time series has reduced by 0.5% for biota and increased by 16% and 3% for sediment and water respectively. A breakdown of trends and status by region and determinand is given in Appendix 1 Tables 1-7 . The assessment methodology is described in the help files on the OHAT.

Regional trends and environmental status were assessed for metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated diphenyl ethers in biota and sediment, polycyclic aromatic hydrocarbon metabolites (PYR1OH) in fish, organotins in sediment, and imposex (VDS) in whelks. For biota, time series from mammals and birds were included in the regional trend assessments, but not in the regional status assessments as the comparability of thresholds for mammals and birds against those for fish and shellfish needs further investigation. Regional health status were assessed for metals,  polycyclic aromatic hydrocarbons, polychlorinated biphenyls and polybrominated diphenyl ethers in biota. The results of the regional assessments are summarised in Appendix 1 Tables 8-12 , with full details available on the OHAT. The changes in regional environmental status since 2022 are given in Table 1.

The biota and sediment CHASE scores are shown in Figure 1 and Figure 2 respectively. The scores for 2022 are also shown for comparison. There is little change for biota, but there are now sediment CHASE scores for the Celtic Sea and the Gulf of Cadiz (both green).

¹The EACs for PAH metabolites depend on the method of chemical analysis used to measure the metabolites. This dependency has now been relaxed somewhat, and the green status reflects the fact that EACs can now be applied to the timeseries in the Norwegian Trench.

²This should be treated with caution. It is an artefact that arises because only a few of the timeseries in the Skagerrak and Kattegat have a BAC; these timeseries typically have a lower contaminant ratio, and this suggests that the BAC is easily met. However, the comparison of all timeseries against the EAC shows that mean levels are only just below the EAC and a green status would be more appropriate.