Fish reflect the pollutant content of sediments and of the entire aquatic ecosystem, in particular the accumulation of pollutants in the food chain.
In 2014 and 2015, the ICPR carried out a first joint investigation programme on the contamination of biota (fish) with pollutants in the Rhine catchment (ICPR technical report no. 216). The evaluation of this pilot project was carried out by the Fraunhofer Institute in cooperation with the ICPR. The technical report no. 252 (available in German, French and Dutch) gives a first comparable overview of the pollution situation of biota in the Rhine catchment.
Mercury pollution was above the environmental quality standard (EQS) for biota at the majority of monitoring sites. Perfluorooctanesulfonic acid (PFOS) was also found to exceed the EQS for at least one fish species. The EQS for dioxins, furans and dioxin-like chlorinated diphenyls (PCBs) was complied with at the monitoring sites investigated. Polybrominated diphenyl ether (PBDE) was clearly above the EQS in all samples. The concentration of the brominated flame retardant hexabromocyclododecane (HBCDD) was always far below the EQS.
During the evaluation it became clear that the proposals for measurements should also be adapted based on the experience gained. The states can apply this revised concept for the biota measurements planned in their area in order to make the results comparable in the future (ICPR technical report no. 259; available in German, French and Dutch).
Contamination of biota is also being investigated in the Internationally Coordinated River Basin Management Plan. The River Basin Management Plan for 2022-2027 shows that there are widespread to area-wide exceedances of the biota EQS in particular for mercury, brominated diphenyl ethers, heptachlor and heptachlor epoxide, fluoranthene and PFOS. These are mainly ubiquitous substances. In Directive 2013/39/EU, some "persistent, bioaccumulative and toxic substances (PBTs) and other substances that behave like PBTs" have been identified as "ubiquitous substances", meaning that they may be present in the aquatic environment for decades at levels that pose a significant risk, even if extensive measures have already been taken to reduce or eliminate emissions of such substances.